Batteries and supercapacitors: fundamentals, materials and devices

Resume : Solid electrolytes with an ionic conductivity larger than 1 mS/cm are key for batteries with an energy density of 1000Wh/l and beyond. Recently, solid composite electrolytes (SCEs) based on confining ionic liquid electrolytes (ILEs) in porous oxide matrices, such as an silica matrix, are gaining interest due to their enhanced conductivity compared to bulk ILE. However, since SCEs are typically made as thick pellets, their properties are the average of the matrix and the confined ILE, rather than the properties of a single interface. Here, we present the direct measurement of the enhanced conductivity of an adsorbed thin film ILE on an silica substrate. We successfully developed a novel method for uniform deposition of ILE thin-films (10-100nm) on planar oxide substrates. The ion conductivity of the ILE was measured lateral to the silica substrate using electrochemical impedance spectroscopy with an interdigitated electrode array. The influence of ILE layer thickness, geometric parameters of the electrodes, and environmental conditions were investigated to determine their impact on the ionic conductivity and activation energy of the ILE. Depositing a thin film of the ILE on an oxide substrate allows to probe the properties of a single interface. This can provide a supplementary approach to study the properties of adsorbed ILE layers on oxides, besides SCE pellets.

Resume : The demand of portable energy has grown during last 25 years, due to the spread of electronic personal devices and it will increase to boost the turn toward an oil-free mobility.[1] Such revolution based on Li-ion cell, has to face many constraints, i.e. raw materials? cost and security issues due to the use of a flammable electrolyte.[2] Na-based solid-state cells could tackle these hurdles. They use the abundant Na+ as charge carrier and they feature a safer, solid material as electrolyte. Herein, a class of compounds of the type NaxAiAj (Ai,j=B12H12, CB11H12, B10H10, CB9H10) were obtained by ball-milling and characterized by in situ X-ray powder diffraction. Their electrochemical stability was systematically measured by cyclic voltammetry in order to determine the most stable anions pair. Then, the novel compound Na4(CB11H12)2(B12H12), that shows a Na+ mobility of 1 mS cm-1 at 20°C and an excellent electrochemical stability (4.1 V vs. Na+/Na),[3] was tested in symmetric cells vs. Na and binary Na-p block element alloys, monitoring the internal cell resistance by in situ impedance spectroscopy. The best performance was obtained in the latter case, providing Na+ shuttling, with low polarization, over several hundred of operating hours. Promising on-going test on complete cell Na2In vs. TiS2 will be also presented. [1] Zeier et al Nat Ener 1 (2016) 16141 [2] Sun et al Nano Ener 33 (2017) 363 [3] Brighi et al J. Power Sources 404 (2018) 7

Resume : Mg batteries utilizing a Mg metal anode with a high-voltage intercalation cathode define a potential pathway toward energy storage with high energy density. However, the realization of Mg batteries is plagued by the instability of existing electrolytes against the Mg-metal anode and high-voltage cathode materials. One viable solution to this problem is the identification of protective coating materials that could effectively separate the distinct chemistries of the metal-anode and the cathode materials from the electrolyte. Using first-principles calculations we map the electrochemical stability windows for non-redox-active Mg binary and ternary compounds in order to identify potential coating materials for Mg batteries. Our results identify Mg-halides and Mg(BH4)2 as promising anode coating materials based on their significant reductive stability. On the cathode side, we identify MgF2, Mg(PO3)2 and MgP4O11 as effective passivating agents.

Resume : Organic solvent based liquid electrolytes today totally dominate the commercial lithium-ion batteries and solid-state electrolytes totally dominate press-releases (and perhaps a hype) about the next generation batteries (NGBs). But there are indeed many more electrolytes concepts to research for any NGB ? for example for Na-ion batteries.[1] Here we will look the at the plentiful synergies possible by emphasizing the roles played by solvents and salts, in a wide sense, in the creation of the charge carrier species needed for a wide range of NGBs: Li/Na/Mg/Ca/Al/Li-S? The materials covered are targeted both experimentally and computationally and stretch from (localized) highly concentrated electrolytes,[2,3] via hybrid organic solvent-IL electrolytes,[4,5] to pure IL based electrolytes,[6] and semi-solid eutectics.[7,8] References 1. G. Åvall, J. Mindemark, D. Brandell and P. Johansson, Adv. En. Mat., 2018, 1703036. 2. V. Nilsson et al., J. Pow. Sourc, 2018, 384, 334-341. 3. E. Flores, G. Åvall, S. Jeschke and P. Johansson, Electrochim. Acta, 2017, 233, 134-141. 4. N. Plylahan, M. Kerner, D.-H. Lim, A. Matic and P. Johansson, Electrochim. Acta, 2016, 216, 24-34. 5. D. Monti, A. Ponrouch, M. R. Palacín, and P. Johansson, J. Pow. Sourc., 2016, 324, 712-721. 6. M. Kerner, N. Plylahan, J. Scheers and P. Johansson, PCCP, 2015, 17, 19569-19581. 7. T. Mandai and P. Johansson, J. Mat. Chem. A, 2015, 3, 12230-12239. 8. J. Forero-Saboya et al., Chem. Comm., 2019, 55, 632-635

Resume : Antimony (Sb) emerges as an attractive anode material for both lithium, sodium and potassium ion batteries (LIB, SIB, KIB) due to its high theoretical capacity of 660 mA h g-1 through a reversible alloying reaction. To develop advanced anode materials to accommodate the huge volume expansion and enhance the conductivity and reversibility of anodes is of great interest. Advanced nanomaterials can offer large surface area, facile strain relaxation upon cycling and efficient electron transport pathway to achieve high electrochemical performance. Hence, we designed a novel hybrid material with Sb nanoparticles anchored in three-dimensional carbon network via a NaCl template-assisted self-assembly strategy, followed by freeze-drying and one-step in-situ carbonization & crystallization. The three-dimensional interconnected macroporous carbon framework can not only stable the architecture and buffer the volume expansion for Sb nanoparticles, but also provide high electrical conductivity for the overall electrode. Consequently, as a sodium-ion battery anode, the SbNPs@3D-C delivers a high reversible capacity, stable cycling performance as well as superior rate capability. We designed and fabricated a novel peapod-like N-doped carbon nanotube encapsulated Sb nanorod composite, the so-called nanorod-in-nanotube structured Sb@N-C, via a bottom-up confinement approach. The N-doped-carbon coating and thermal-reduction process was monitored by in-situ high-temperature X-ray diffraction characterization. Then, we employed Sb@N-C as an anode for LIB, SIB and KIB, Sb@N-C displayed the best long-term cycle performance among the reported Sb-based anode materials and impressive rate capability up to 20 A g-1. Especially in the case of KIB, the introduction of KFSI electrolyte salt functions as an effective strategy for greatly boosting electrochemical performance. We also identified the potassiation of Sb anode is quite reversible and undergoes multistep processes, combining solid solution reaction and two-phase reaction. Our work presented here can inspire new thought in constructing novel nanostructures and accelerate the development of high-performance alloying-type anodes for energy storage applications. References [1]. L. Q. Mai, M. Y. Yan and Y. L. Zhao, Nature 2017, 546, 469. [2]. W. Luo, F. Li, J. J. Gaumet, P. Magri, S. Diliberto, L. Zhou and Liqiang Mai. Adv. Energy Mater. 2018, 201703237. [3]. W. Luo, F. Li, Q. Li, X. P. Wang, W. Yang, L. Zhou and L. Q. Mai. ACS Appl. Mater. Interfaces 2018, 10, 7201?7207. [4]. W. Luo, P. Zhang, X. Wang, Q. Li, Y. Dong, J. Hua, L. Zhou and L. Q. Mai. J. Power Sources 2016, 304, 340-345. [5]. X. Ma, W. Luo, M. Y. Yan, L. He and L. Q. Mai. Nano Energy 2016, 24, 165?188.

Resume : Zinc-ion batteries (ZIBs) have garnered much interest as a potential alternative for lithium-ion batteries. This is largely due to ZIBs being environmentally benign, cheap, safe, and possessing a high theoretical capacity and energy density. However, many materials used for ZIB cathodes experience poor capacities, poor cyclability or a combination of both. A more complete understanding of the battery reaction mechanism is necessary for the development ZIB cathodes. In this work, manganese oxide (MnOx) is deposited onto several different conductive substrates (e.g., stainless steel and porous carbon) by pulse electrodeposition, and then annealed, for use as ZIB cathodes. MnOx is inexpensive, abundant, environmentally benign and possesses a high capacity. The electrolyte used for electrodeposition consists of Mn(CH3COO)2, CH3COONa and sodium dodecyl sulfate (SDS). Microstructural characterization techniques, including electron microscopy (SEM and TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), are used to characterize the deposited MnOx before and after battery cycling. Cyclic voltammetry and galvanostatic charge/discharge tests are used to assess the electrochemical performance of MnOx. The electrodeposition conditions are optimized based on both electrochemical and microstructural characterization to obtain high performance electrodes. Preliminary results show capacities up to 369 mAh/g.

Resume : Metal closo-borates and related borate compounds are an emerging class of solid-state elec-trolytes with high ionic conductivity, intrinsic chemical and electrochemical stability and good processability. We have recently reported a room-temperature Na+ ion conductor within this family, namely Na2(B12H12)0.5(B10H10)0.5 which allowed the stable cycling of the first 3 V all-solid-state battery using this class of compound.[1,2] Here we discuss the peculiar temperature dependence of the ionic conductivity of Na2(B12H12)0.5(B10H10)0.5, which exhibits three regimes governed by distinct conduction mechanisms. Specifically, a glass-like transition identified by X-ray diffraction and thermal characterization causes an increase of activation energy at -50°C. Above this temperature, an activation energy of 0.6 eV is observed, higher than the local microscopic energy barrier of ~0.35 eV seen by nuclear magnetic resonance and neutron scattering experiments. This local energy barrier is only reflected in the conductivity activation energy above 70 °C. We show that these deviations from an Arrhenius conductivity behavior are a direct consequence of disorder caused by the anion dynamics as well as ion-ion interactions upon diffusion. The unique dynamical features of the closo-borate anions could also explain the complex Arrhenius conductivity observed in several related compounds. [1] L. Duchêne et al., Chem. Commun., 2017, 53, 4195. [2] L. Duchêne et al., Energy Environ. Sci., 2017, 10, 2609

Resume : State-of-the-art electrolytes used in Li-ion batteries contain the electrolyte salt LiPF6, susceptible to undergo defluorination reactions and form toxic and corrosive compounds, such as HF. Yet, fluorine-containing electrolytes are often considered necessary for enhanced battery performance. Alternatively, replacing LiPF6 with fluorine-free salts would reduce cost, increase safety and decrease toxicity, both in the manufacturing and recycling processes. Furthermore, additives in the electrolyte are another common source of fluorine, not least fluoroethylene carbonate (FEC) which can form a stable solid electrolyte interphase (SEI). The SEI is particularly important for silicon-based electrodes as they suffer high volume changes upon cycling. Herein, we compare the cell performance and chemical composition of the SEI of fluorinated and non-fluorinated electrolytes in NMC/Si-Graphite full cells. The main outcome of this project is the high cycling stability of the cell containing non-fluorinated electrolyte (based on lithium bis(oxalato)borate salt and vinylene carbonate as SEI-forming additive) comparable to a cell with a fluorinated electrolyte (LiPF6-based) containing FEC and VC. Additionally, both of these cells with different electrolyte compositions outperform the one containing the conventional LiPF6-based electrolyte, without additives, which feature a rapid capacity fade.

Resume : Electrolytes provide electrical conductivity through the transport of ions and is an indispensable component for electrochemical energy devices such as rechargeable batteries, electrochemical capacitors, and fuel cells. The electrolytes (LiPF6, LiClO4, and LiCF3SO3) commonly used in lithium ion batteries inevitably undergo side reactions in electrochemical cells which can lead to explosion, electrode corrosion, and device deterioration.1,2 Although many studies have been carried out to solve these problems, development of electrolytes satisfying all the requirements such as electrochemical and thermal stability, high ion conductivity, environment friendliness and low manufacturing cost is still far away. Herein, we report a new class of electrolyte salts based on a polyanionic carbon dot (C-dotx-). The new electrolyte salt comprises ionic salts between lithium cations (Li+) and C-dotx- polyanions. The physicochemical properties of the LixC-dot electrolyte component were investigated via transmission electron microscopy (TEM), thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and cyclic voltammetry (CV). The LixC-dot electrolyte shows a wide range of electrochemical stability (3.5 V) and high thermal stability (Td: 655 oC, temperature at 5% weight loss), high cation number (Li+ ? 24) and cation conducting property (tLi+ = 0.8). Based on these results, liquid LixC-dotx- electrolytes were applied to Li//Li4Ti5O12 (LTO) half cells. The Li//LTO half cells fabricated using LixC-dot electrolytes in a mixture of DEC:EC (1:1 v/v) exhibited a slightly lower electrochemical performance than those based on 1.1 M LiPF6 electrolytes due to low concentrations of LixC-dots. However, despite its 550-fold lower concentration, electrochemical performance comparable to 1.1 M LiPF6 at 1 C-rate appeared. Furthermore, it was confirmed that the Li / LiCoO2 (LCO) half cell was operated stably with LixC-dot electrolyte.

Resume : It is often said that the electrolyte is the most crucial component of a battery. It must indeed be stable in contact with both electrodes, highly reducing and highly oxidizing. This stability which cannot be thermodynamical when the voltage span is > 3.8 V implies the formation of a SEI, with friendly properties (covering, ionically conductive, electronically insulating). Except for ceramics the electrolytes are obtained from the addition of a salt to a “solvent” that can be a liquid (organic carbonate mixtures), alternatively a polymer like PEO, or more recently, a polyester. The salt can be discrete, or its negative charges affixed to a polymer, resulting in electrolytes whose conductivity is solely due to cations (Li+, Na+). In practice, mainstream Li-ion batteries rely exclusively on the use of LiPF6 in carbonate solvents. LiPF6 is thermally unstable, releases easily HF from hydrolysis that corrodes the electrodes, but it does not corrode the aluminium current collectors even at potentials ≈ 5V. Conversely, in polymer electrolytes, the salts are almost invariably from the imide family like LiTFSI, Li[CF3SO2)2N] or LiFSI, Li[FSO2)2N]. While in the lab both salts give the same level of (high) conductivity, in industry only LiTFSI is used for the fabrication of Li° batteries deploying the cost-saving extrusion of electrolyte at temperatures ≈ 250°C, beyond the stability of LiFSI. However, imide salts corrode Al° above 3.8 V, which is also the onset of oxidation of the ether groups in the polymer. Solid-state batteries have been limited to Li° | |LiFePO4 at 3.5 V. Up to now, the increase in the cation transfer number has only been possible by tethering the anions to a polymer that was then mixed with a solvating polymer (PEO, comb oligoether polymer …) resulting in strictly T+ = 1 electrolytes. This is to be compared to TLi+ ≈ 0.2 for either liquid or PEO-based electrolytes. The chemistry that has been used up to now is relatively complex and the monomers usually involve styrene moieties that deleteriously rigidify the polymer blend. In this respect, we show that new polysalts can be derived from more flexible poly acrylic acid (PAA) with —COOH being replaced by Li+[—CO(N )SO2CF3] in a simple one-pot from PAA with decent conductivities when mixed with PEO. In an alternative approach, we chose a strategy to design anions that could interact with themselves or with the polymer backbone to slow their motion, increasing thus the TLi+. We found that the introduction in ad hoc proportions of polarized protons in the structure effectively results in hydrogen bond formation either with other anions in the vicinity or to the oxygen centers on the polymer. For instance, the anion MTFSI [CH3SO2NSO2CF3] and DFTFSI [CH3SO2NSO2CF3] have TLi+ ≈ 0.5, a considerable increase vs. normal salts. An overview of the properties and perspectives given by these new strategies will be given.

Resume : Polymer electrolytes are considered to play a decisive role for the realization of safer rechargeable batteries and may, additionally, allow for the employment of lithium metal anodes, thus, paving the way for significantly higher energy densities.[1,2] Beside mechanical strength, especially two characteristics appear to be of paramount importance: (i) Single-ion conductivity to prevent the reversed cell polarization, negatively affecting the long-term cycling stability, and (ii) a homogeneous lithium/sodium deposition upon charge to avoid the dendritic metal deposition.[2] In a very recent study, we showed that both features can be simultaneously realized by covalently tethering the anionic function to a self-assembling multiblock copolymer, providing highly efficient Li+ transport pathways and, moreover, a remarkable electrochemical stability towards oxidation.[3] Following these results, we investigated the compatibility of these (swollen) single-ion polymer electrolytes with high-energy Li[Ni0.6Mn0.2Co0.2]O2 cathodes and the extension of its application to secondary sodium batteries, highlighting the outstanding performance and great versatility of these electrolyte systems. References [1] J. Kalhoff, G.G. Eshetu, D. Bresser, S. Passerini, ChemSusChem 2015, 8, 2154. [2] D.T. Hallinan, N.P. Balsara, Annu. Rev. Mater. Res. 2013, 43, 503. [3] H.-D. Nguyen, G.-T. Kim, J. Shi, E. Paillard, P. Judeinstein, S. Lyonnard, D. Bresser, C. Iojoiu, Energy Environ. Sci. 2018, 11, 3298.

Resume : Dry polymer electrolytes based on poly (ethylene oxide), PEO, and Li-salt complexes are one of the cheapest, environmentally friendly and promising materials for developing safe, cheap and durable all-solid-state Li-ion batteries. The rigid structures that are interesting from the point of view of application in all-solid-state battery cells are characterized by low conductivity at ambient temperatures. Dispersion of oxide nanoparticles inside the PEO-matrix greatly improves the physicochemical properties of the complex due to the physical interaction between the grains and the polymer matrix. Unfortunately, such a great effect drops at high loading-content, mostly above 10 wt%, owing to agglomeration of the nanoparticles and the consequence Li-ion blocking effect. In our work, we have proposed a novel approach that leads to a porous composite electrolyte consisted of higher weight fraction of nanoporous silica than PEO polymer. Here, the polymer-salt complex is being entirely soaked inside the mesoporous silica matrix that offers the mechanical support for the electrolyte. To do this, the walls of silica pores are tailored in the controlled manner with low molecular weight PEO polymer chains. The studied system that contained 70 to 80 wt% of SiO2 showed high conductivity, excellent mechanical strength and wide electrochemical potential window. Textural and structural properties of the starting materials and the hybrid electrolytes will be presented. Furthermore, the electrochemical properties of the porous electrolytes will be discussed to demonstrate the feasibility of our materials as solid electrolytes in all-solid-state Li-ion battery cells.

Resume : Solid electrolytes play an upcoming role in future battery cell concepts in terms of improved safety, higher energy density and a wider temperature range of operation devices[1]. Lithium containing solid electrolytes are already used in thin-film microbatteries, where LiPON has been introduced in 1999 by Neudecker and Dudney[2]. This work deals with lithium phosphorous sulfuric oxynitrides (?LiPSON?). With such thin films the important properties of lithium ion conductors LiPON (stability against lithium metal) and LiSON (good ionic conductivity) should be combined. Using the technique of radio-frequency sputter deposition thin films have been fabricated by use of a target with a composition of about 50wt% lithium phosphate and 50wt% lithium sulfate and a changing argon/nitrogen mixture as process gas. The important physical and electrochemical properties like composition of the thin films, morphology and ionic conductivity have been investigated using x-ray photoelectron spectroscopy (XPS), x-ray diffraction (XRD), scanning electron microscopy (SEM) and electrochemical impedance spectroscopy (EIS). The composition of the thin films is found to change due to the different fractions of process gases used. A higher sulfur content in the films is expected to increase the ionic conductivity. This expectation was confirmed via XPS and EIS measurements. The highest fraction of sulfur is about 1.3 at% for 8 sccm nitrogen and 70 sccm argon as process gases. Related to the combination of the process gases also the optical bandgap shifts in the range of 3.7 eV up to 5.3 eV. Furthermore the transmittance in the near ultraviolet range (300 nm to 380 nm) is above 60% and in the visible range above 80% for most of the thin films. According to these results the use of such solid electrolyte thin films in electrochromic devices (EC devices) is feasible. [1] J.Janek, W.Zeier, Nat.Energy, Vol.1, September 2016, DOI:10.1038/NENERGY.2016.141 [2] N.J.Dudney, B.J.Neudecker, Current opinion in Solid State and Material Science 4 (1999), 479-482

Resume : All solid-state batteries are a promising option towards high energy and power densities, as well as drastically reduced safety risks. A wide variety of solid-state electrolytes (SSEs) have been developed in the past, ranging from inorganic ceramics to solid polymers.[1] However, their practical application has been limited to elevated temperatures (80 °C) as the ion conductivity at room temperature has been much lower than that of organic solvent based liquid electrolytes.[2] To address this problem, we set out to create a composite SSE based on two crystalline materials with the ion conduction based on two different mechanisms: percolation and ion hopping. One material is based on a matrix of hyper-valent molecules i.e. with large internal dipole moment, while the second is a supra-molecular crystal composed of ordered arrays of nano-structured channels containing lithium ions.[3,4] The resulting crystalline composite shows an appreciable ionic conductivity; 10-5 S.cm-1 at room temperature, and low activation energy for the ion transport ? fitted both by Arrhenius and VFT. The thermal properties were investigated by TGA and DSC, and the overall and local structure by XRD, FTIR and Raman spectroscopy. Finally, the SSEs were electrochemically examined by LSV and CV. This work was funded by ?Batterifondsprogrammet? of the Swedish Energy Agency. References [1] J.B. Goodenough, P. Singh, J. Electrochem. Soc. 162 (2015) A2387?A2392. [2] P. Knauth, Solid State Ionics 180 (2009) 911?916. [3] T. Mizumo, R. Fujita, H. Ohno, J. Ohshita, Chem. Lett. 40 (2011) 798?800. [4] M. Moriya, K. Nomura, W. Sakamoto, T. Yogo, CrystEngComm 16 (2014) 10512?10518.

Resume : All-solid-state batteries have been presented as the ideal solution to address i) the safety limitations of conventional Li-ion batteries by suppressing the flammable organic electrolytes and ii) the problem of insufficient energy densities. To date, two types of solid Li-ion electrolytes have been mainly studied, namely, sulfur-based and ceramic-based materials. Despite the progress in the development of superionic conductor, many aspects of their reaction mechanisms and stability upon cycling still remain non-elucidated. In order to get a better insight about their stability upon cycling, the development of a reliable electrochemical cells is thus of a prime importance when studying battery materials in operando mode during cycling. This is never an easy task, since the design of such cells has to be adequate to the technique of a choice and meet all necessary requirements. However, once a proper design is found, the surface, the bulk, the interfaces, and finally the combination of those can be studied and lead to the elucidation of the reaction mechanisms, thus further improving the battery technology. Through this presentation, we will use bulk, surface and imaging techniques to better understand the limitation of all solid state batteries. As an example, Operando neutron imaging has been employed to understand the Li diffusion within the electrode and inside an all-solid state batteries employing Li3PS4 as solid electrolyte whereas operando X-ray microscopic tomography was employed to follow the possible electro-mechanical fracture occurring during cycling and the possible impact on the electrochemical performance.

Resume : This study revealed the importance of large area as well as multi modal imaging of batteries. Light microscope images allow a fast large area scan and in-situ dendrite grows observation in batteries but the resolution is often not good enough to be able to study interfaces or surface morphologies. The MultiSEM, an electron microscope with 61 electron beams, allowed a 1mm by 1mm high-resolution large area scan and uncovered very different material properties within the inspected region. In-situ Raman, SIMS and TOF-SIMS measurements laid out correlations between different material condition and the respective local lithium distribution. In addition, electron beam absorption current (EBAC) experiments allowed a surface resistance and absorption current measurement. These results give direct evidence for material ageing and/or process errors. It was demonstrated that large area and multimodal in-situ lithium distribution studies and the comparison with the overall performance parameter enable an understanding of the context of batteries.

Resume : Despite Li10GeP2S12 (LGPS) solid electrolytes (SEs) have achieved a highly ionic conductivity of 10-3?10-2 S cm-1 at room temperature, which is comparable to commercially flammable liquid electrolytes, incorporating these materials into all-solid-state Lithium ion batteries (ASSLIBs) has proven difficult in obtaining high energy density and long cycle life. The challenges for ASSLIBs using LGPS SEs are still huge as a result of sluggish kinetics and material incompatibility at the interfaces of the electrolytes and electrodes. In this study, we have explored a new LGPS-based composite electrolyte through LiBr incorporation into LGPS based on the premises: (1) LiBr could be dissolved in LGPS precursors to evolve solid solutions as a protectively interlayer between the LGPS electrolytes and electrodes. (2) The low-melting-point LiBr (552 ?) in the composite electrolytes would serve as an effective binder to enhance contact area and wetting properties along LGPS grains and across LGPS/electrode interface. (3) The addition of LiBr can increase disorder degree of Li distribution to weaken interactions between Li+ and anion framework, leading to increase in the associated ionic conductivity. (4) The partial substitution of Br- with the larger ionic radii of (0.196 nm) for the smaller size of S2- (0.184 nm) can be expected for broadening Li-ion conduction pathway in the composite SEs. For these reasons above, we have investigated the effect of LiBr incorporation on microstructure, and intrinsic and interfacial Li-ion transport properties of LGPS SEs. More detailed information for evaluating and explaining interfacial and cyclic properties of ASSLIBs using the composite SEs will be illustrated in this presentation.

Resume : Due to the high energy density, long lifespan, no memory effects and environmental friendliness, lithium-ion batteries (LIBs) represent one of the most attractive energy storage systems, playing more and more important role in our life. On the same time, gas generation as a result of different mechanism such as electrolyte decomposition and phase changes in the cathode active material is a major drawback for lithium-ion batteries, leading to reduced cycle life and cell failure. In this context, large LFP/graphite pouch cells (ICSI Energy format) for different electrode loading and commercial standard electrolyte were developed and tested. X-ray diffraction measurements and SEM-EDX analysis were conducted to obtain structural and morphological information for the electrodes before and after testing. In order to collect the generated gases, a simple method based on an air bag was used. The resulted gases were characterised by gas chromatography/mass spectrometry.

Resume : With the rapid development of new-generation flexible electronics, future power sources are required to be mechanically flexible and also have both high energy and large power as well as long cycle life. Flexible Supercapacitors have been widely investigated by the reasons of their excellent electrochemical performance such as high power delivery, operational safety, long cycle life and flexibility. Flexible electrodes, owing to their unique advantages like flexible and wearable, have drawn many attentions. However, there still exist some challenges to improve flexible electrode materials? conductive property and excellent cycle stability. In this paper, NiMoO4/Polypyrrole (PPy)/carbon cloth (CC) flexible electrode is proposed, using a hydrothermal synthesis method and a chemical polymerization process, to solve these issues. The designed NiMoO4/PPy/CC electrode has following advantages: 1) the electrode is flexible, light weight, good electrical conductivity (PPy possesses higher conductivity which can ensure the conductivity of the materials). 2) the NiMoO4 nanowires can directly grow on the substrate without using any binders and provide a frame support for PPy nanoparticles cladding, which can effective reduce the charge-transfer resistance and shorten the path of ion diffusion and electron transport. 3) nanocomposites can directly provide the current channels and transfer the electrons more efficient. 4) the hybrid structure can prevent the electrode material?s damage from volume change in the charge-discharge process and prove the long cycle life. 5) the designed nanocomposites can take advantages of all good function of components and achieve a synergistic effect. So the electrode exhibits a high areal specific capacitance of 1.64 F cm-2 at a current density of 1mA cm-2 and capacitance retention 98.2% after 2000 cycles. The results showed that the NiMoO4/PPy exhibit remarkable electrochemical performance, which could be utilized as a promising pseudocapacitive electrode material for high performance flexible supercapacitors. (This paper is funded by the International Exchange program of Harbin Engineering University for Innovation-oriented Talents Cultivation.)

Resume : In the Era of sustainable energy technologies, several efforts have been made to develop intelligent miniaturized electronic devices that can be applied as wearable technologies (clothes, bracelets, implants). For these devices, an energy storage system that can charge faster and store energy for a long period of time is highly desired. In this sense, several types of energy storage technologies have been developed and optimized such as batteries and supercapacitors (SCs). This work focuses the development of solid-state hybrid (hy) SCs based on transition metal oxides (MnxOy) and carbon nanomaterials (CN) incorporated on textile substrates. The hy nanomaterials were prepared by a new one-step coprecipitation route, resulting on MnxOy with different phases (??MnO2 and tetragonal hausmannite) and morphologies (cubic and needle-like clusters) immobilized on the CN. Symmetric and asymmetric textile SCs were then produced using the parent CN and hy nanomaterials and a solid-gel electrolyte, with posterior evaluation of the electrochemical performance. A maximum specific capacitance of 88.79 F/g was achieved for the asymmetric SC, leading to an energy density of 125.30 W.s/g and a power density of 0.122 W/g. An enhancement of 8.8% of the specific capacitance was achieved relative to the symmetric CN-based SC, due to the simultaneous occurrence of oxidation-reduction reactions and a non-Faradaic type charge storage mechanism. Work funded by FEDER through COMPETE 2020 and by Portuguese funds through FCT/MEC under Program PT2020 in the framework of the projects PTDC/CTM-TEX/31271/2017, UID/QUI/50006/2013-POCI/01/0145/FEDER/007265 and UID/NAN/50024/2013. CP thanks FCT for Investigator contract IF/01080/2015. RSC thanks UniRCell Project (POCI-01-0145-FEDER-016422) for a MSc. grant.

Resume : Rechargeable magnesium (Mg) batteries are expected to be an future alternative to lithium (Li) -based batteries because of their potential for high energy density and high safety while suppressing the cost. One of the key issue to be solved is the poor conductivity of Mg ion. The diffusion of divalent Mg ion is limited due to the strong electrostatic interaction with the anions. This effect is crucial in a solids, thus the development of Mg solid electrolyte with high ionic conductivity is strongly required. Recently, a solid nanocomposite electrolytes (nano-SCE), which is composed of ionic liquid with Li-salt (ionic liquid electrolyte: ILE) supported by porous silica matrix, was developed [1]. The conductivity of nano-SCE exceeded that of pure ILE itself because the association between Li ion and anion was weaken due to the change of molecular interaction on the silica surface. In this paper, we applied the surface promotion technology in nano-SCE to Mg ion conductors. A nano-SCE with high Mg ion conductivity was developed by sol-gel process. The conductivity of Mg nano-SCE showed higher than that of ILE, and reached to 2.3 x 10-3 S/cm, which is comparable to the organic liquid Mg electrolyte. The impact of the ionic liquids molecule and the silica matrix on the ionic conductivity was discussed combined with the structural analysis and ab-initio calculation results. [1] P. M. Vereecken et al, ECS Meeting Abstracts, vol. 470, pp. MA2018-02, 2018.

Resume : When looking for alternative anodes for lithium-Ion batteries (LIBs), two big material classes are considered: (i) alloying materials and (ii) conversion compounds like transition metal (TM) oxides. Unfortunately, these materials show great volume variation and large voltage hysteresis, respectively. To face these issues, the combination of the two mechanisms led us to a new material class: conversion/alloying materials1. Recently, we examined the effect of the TM dopant in SnO2 and found that the presence of manganese is beneficial for the full-cell energy density, while cobalt improves the cycling stability and rate capability2. Herein, we present the further optimization by inserting more than one dopant, employing an easily scalable hydrothermal synthesis method, to combine the favorable effects of different doping elements. Indeed, the introduction of different TMs allows adjusting the dis-/charge potential and, thus, further enhancing the achievable full-cell energy density, while simultaneously improving the cycling performance and rate capability. Besides the potential application of these materials in future LIBs, the gained insights and enhanced understanding of the effect of the TM dopant is essential to develop general guidelines for the development of advanced conversion/alloying anodes. References 1. D. Bresser, S. Passerini, and B. Scrosati, Energy Environ. Sci., 9, 3348?3367 (2016) 2. Y. Ma et al., Sustain. Energy Fuels, 2, 2601?2608 (2018).

Resume : To develop high performance carbonaceous anode materials for lithium ion battery it is important to understand the effect of heteroatoms like nitrogen. We investigate the hard carbon with and without nitrogen doping using experimental and first principle calculations. The size and nitrogen doping of hard carbon was controlled by the amount of salts added during the synthesis process. In this study, nitrogen-doped mesoporous hard carbon spheres of micron and nano sizes are synthesized to understand the effect of size and nitrogen doping on the electrochemical performance. Gravimetric capacity has been found to be 506 mAhg-1 and 475 mAhg-1 for undoped micron and nano-sized carbon spheres. After nitrogen doping, the gravimetric capacities of both nano and micron sized carbon spheres increases by 6.9 % and .8 % respectively. Nitrogen doping enhances the cycle stability of micron and nano carbon spheres, with increase in capacity retention after 200 cycles by 6 % and 15 % respectively. The enhancement is attributed to a significant decrease in volume expansion and increase in electronic conductivity due to the nitrogen doping. This was further confirmed by using Density Functional Theory (DFT) based computation. The excellent electrochemical performance of nitrogen-doped hard carbon is due to the drastic reduction in volume expansion rate during lithiation along with increased porosity and electronic conductivity. Furthermore, this synthesis method can be extended to other carbon sources to get nitrogen-doped hard carbon with sizes varying from nano to micron.

Resume : Manganese sulfide (?-MnS) is an appealing anode material for lithium-ion batteries (LIBs), due to larger theoretical capacity and lower redox potential compared to other metal sulfides ? besides being eco-friendly and less expensive. Despite these advantages, ?-MnS-based anodes often suffer from several problems, such as volume variation, low electrical conductivity, and sluggish Li-ion mobility, thus resulting in poor electrochemical properties. Metal-organic frameworks (MOFs) derivatives, especially metal sulfides/carbon composites, have attracted interest as anode materials for LIBs due to their porous structure and tunable composition. The features of MOFs derivatives not only can shorten the ions diffusion pathway, but effectively alleviate the volume variation and improve the overall electronic conductivity. Thus, using Mn-MOFs as a precursor, ?-MnS/S-doped C micro-rod composites with mesoporous structure were synthesized by a one-step sulfidation reaction. Owing to the mesoporous structure, nanoscale ?-MnS particles, and S-doped carbon matrix, the resulting products shows superior Li-storage in half/full cells. Importantly, in situ XRD studies on electrodes employing various metal foil as current collector reveal new insights on the reaction mechanism of ?-MnS. Finally, In situ dilatometry measurements demonstrate that the advanced structure of as-obtained composite restrains the electrode volume variation upon repeated (dis-)charge processes.

Resume : Batteries based on naturally abundant, light metal anodes (such as Ca and Mg) and multivalent ion host cathodes can potentially achieve very high energy densities at relatively low cost and environmental impact, thus representing a compelling alternative to currently available Li-ion systems. While reversible Ca metal plating and stripping in conventional alkyl carbonate based electrolytes has been accomplished [1,2], unraveling cathode materials with fast and reversible ion mobility at high operating voltages remains a major open challenge, mainly hampered by the slow diffusion kinetics in the solid state of multivalent ions. Thus, besides the exploration of new materials, revisiting traditional layered intercalation hosts appears as a very useful tool to gain further insight into the fundamentals of divalent ion intercalation. In this context, a thorough study of the electrochemical intercalation of Ca2 in layered TiS2, in alkyl carbonate based electrolytes, is herein presented [3]. Fundamental insights on the insertion process are acquired through X-ray diffraction. Ca2 insertion is unambiguously proved by using both X-ray diffraction and differential absorption X-ray tomography at the Ca L2 edge and the reversibility of the process is demonstrated at moderate temperature. Different phases can be formed upon reduction of pristine TiS2, whose amount and composition dependon the experimental conditions employed. A comparative study with Mg2 containing electrolytes and other conventional intercalation hosts, such as V2O5, was also carried out. Careful examination of results highlights the potential relevance of side reactions in these system and the need to use several complementary characterization techniques to unambiguously assess divalent ion intercalation. [1]A. Ponrouch, C. Frontera, F. Bardé and M. R. Palacín, Nat. Mater. (2016), 15, 169. [2] A. Ponrouch, M. R. Palacín, Curr. Opin. Electrochem. (2018), 1. [3] Tchitchekova D.S., Ponrouch A., Verrelli R., Broux T., Frontera C., Sorrentino A., Biskup N., Arroyo-de Dompablo M.E., Bardé F., Palacín M.R., Chem. Mat. (2018), 30, 847.

Resume : Metal oxides (MOs) are regarded as alternative anode materials due to their high theoretical capacity, nontoxic and low cost. However, it is unable to take into account of high capacity and stable cycling performance which hinder their practical applications. Here, we improve both specific capacity and stability of transition metal oxides by following two aspects: 1) composing with CNTs through a hierarchical coaxial nanostructure, and 2) introducing with massive oxygen vacancies. The synergistic reaction between TMOs (shell) and CNTs (core) through a hierarchical coaxial nanostructure can effectively enhance conductivity and reduce the Li diffusion distance, and consequently improve the rate performance, cycling stability and specific capacity. We develop an unique three-dimensional sponge-like CNT bulk material with excellent conductivity, high porosity and stable compressibility, which can be used as an ideal current-collector. Titanium dioxide (TiO2) is directly deposited onto the CNT sponge as a coaxial structure, forming a highly porous composite sponge electrode without any redundant additives (such as conducting agent and binder). As an anode for LIBs, TiO2@CNT sponge exhibit stable charging/discharging plateau voltages, higher capacity, better stability and rate performance comparing with pure TiO2 electrodes. Massive oxygen vacancies are introduced into MOs to further improve the performance of LIBs. A unique electric field assistant annealing method is developed to treat the TiO2@CNT sponges. Under the combined function of the temperature and electric field, oxygen vacancies are rapidly formed and migrated through TiO2, forming an amorphous TiO2-x@CNT sponge with a large number of oxygen vacancies (~45%) uniformly distributed in the hole TiO2-x. As an anode for LIBs, TiO2-x@CNT exhibits a specific capacity as 605 mAh/g (under current density as 200 mA/g) which is 270mAh/g higher capacity than the theoretical capacity of anatase TiO2 (335 mAh/g), and even under high rate condition (10000 A/g), the capacity is stable as 110 mAh/g. This extraordinary performance is originated from the massive uniformly distributed oxygen vacancies which significantly enhance the conductivity and Li diffusion ability of TiO2-x. Using this electric field assistant annealing method, massive oxygen vacancies can be introduced into many other MOs (such as MnO2 and SnO2). In conclusion, we efficiently improve the lithium storage performances of MO electrodes by composing CNT sponge with a coaxial structure and introducing massive oxygen vacancies uniformly. Our work has a prospect in achieving advanced LIB anodes with stable and high rate capacities for many practical applications.

Resume : The demand for clean energy generation has been extensively propelled associated to environmental factors and climate changes. In this context, new materials as electrodes for storage and conversion devices have been widely researched such as transition metal oxides, carbon fibers (CF), graphene oxides (GO), among others. Thus, the purpose of this study was to evaluate the influence of oxidative process on CF to produce CF/GO binary composites in order to optimize their electrochemical responses. Firstly, the CF samples were submitted to chemical oxidation process using nitric acid 60% (v/v) at 110 °C under reflux at different oxidative times (3, 5, 15, 30 min). Subsequently, GO deposition (6mg mL-1) was performed by dip coating method for 1 min. CFs as well as composites were analyzed by scanning electron microscopy, Raman spectroscopy, contact angle, BET surface area, and X-ray diffraction. Based on these analyzes, it was observed that the oxidative treatment did not cause significant changes in CF structures, keeping the material integrity. On the other hand, the electrochemical analyzes of cyclic voltammetry and charge and discharge tests showed that electrodes after oxidative treatment present a more capacitive profile, which indicates that the suitable surface oxidation favored the charge accumulation. After the GO incorporation, these effects were intensified showing the electrodes very promising for application in supercapacitors.

Resume : Al-ion batteries have attracted tremendous attentions due to lack of dendrite growth, low costs and high volumetric capacity when Al metal is directly used as anode. However, the development of Al-ion batteries is hindered by sluggish kinetics of Al3+ intercalation/deintercalation, associated with strong electrostatic force between intercalation framework of host materials and trivalent Al3+ ions. Thus, a concept of hybrid Al-Li-ion battery is proposed to improve the kinetics and maintain the dendrite-free formation of Al-ion batteries. In the hybrid battery, Li+ ions intercalate/deintercalate into/from the cathode materials because of faster ion transport of Li+ compared to Al3+ while Al strip/deposit on the surface of Al anode due to higher redox potential of Al/Al3+ compared to Li/Li+. Subsequently, a hybrid battery, composed of vanadium oxides nanosheets as cathode, Al foil as anode and [EMIM][Cl]/AlCl3/LiCl as electrolytes, has been successfully fabricated. This hybrid battery delivered a high volumetric capacity of 32.5 mAh/cm3 at 100 mA/cm3 and maintained 21.5 mAh/cm3 even at 1 A/cm3. More impressively, the capacity could be retained 70.1% after 3000 cycles, much better than other Al-ion batteries reported. The excellent electrochemical performance could be attributed to the improved kinetics with the introduction of Li+ ions and the porous structures of the cathode material. Therefore, this work demonstrates a safe, cost-effective and highly-competitive battery.

Resume : Among the modern electrochemical energy conversion and storage technologies for utilization of renewable energy sources, an all-vanadium redox flow battery (VRFB) is a promising candidate for medium- to large-scale grid applications. With the energy density stored in vanadium electrolytes in tanks and the power generation at the stack via the redox activities of vanadium couples (V(IV)/V(V) and V(III)/V(II) at the electrodes makes decoupling of energy and power a salient feature of this system. However, the activity of redox reactions decreases at the electrodes at higher current densities due to the increase of overpotentials, thus hindering broader market penetration of this technology. Therefore, we hereby, propose a carbon felt electrode decorated with tin oxide nanoparticles to overcome the issues of low discharge capacity as well as energy efficiency. The VRFB with the SnO2 deposited carbon felt electrode exhibited an energy efficiency of 77.3% with a discharge capacity of ~24 Ah L-1 at a high current density of 150 mA cm-2. In addition to this, the cycling stability of the system was also found to increase as compared to pristine carbon felt electrode. The pre- and post-cycling physical and chemical stability of the electrode was probed by characterization techniques of scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy and synchrotron-radiations based absorption spectroscopy which confirmed the successful deposition of tin oxide nanoparticles on the carbon felt and their stability after charge/discharge cycling. Therefore, tin oxide can be a suitable, cost effective and high-performance electrocatalyst for VRFB technology.

Resume : Na3V2(PO4)2F3 (NVPF) has attracted much attention as cathode material for Na-ion batteries thanks to the inductive effects allowing for a high working potential combined with a high theoretical specific capacity due to the multiple oxidation states of vanadium [1-2]. One of the limitations of NVPF electrodes is their low intrinsic electronic conductivity; therefore, we have prepared composites of NVPF with conductive carbon sources to ensure higher electronic conductivity of the electrodes. NVPF and NVPF/carbon composite materials were prepared by spray-drying as in our previous work [2]. Spray drying is a cost-effective and up-scalable route to prepare homogeneous multi-component powders, thus making it a suitable method to incorporate carbon in the composite powder [4]. The influence of different carbon sources on structural and morphological properties of NVPF and NVPF/carbon composite was investigated by combining several characterization techniques (XRD, SEM and TEM). The chemical composition at the surface of the powders were studied using XPS. Raman spectroscopy was used to evaluate the quality in disordered carbon materials and its electronic conductivity [3] and compare the results with the results from EIS and cycling performance of different samples. References: [1] Shakoor et al., Chem. 22,2012, 20535. [2] Eshraghi et al., Electrochimica Acta, 228, 2017, 319. [3] Mahmoud et al., J Solid State Electrochem. 22, 2018,103. [4] Vertruyen et al., Materials 2018, 11, 1076.

Resume : The great importance of Li-ion mobility and the electrode-electrolyte interface interactions for ensuring good performance and high reliability in Li-ion batteries has inspired, in the past few years, the development of a wide range of electrolyte formulations. Accordingly, probing the electrolyte solution structures is now considered pivotal to extend the performance limit of the current Li-ion batteries. However, comprehension of solution structure and ion transport behavior in Li-ion batteries is far from being fully understood. For the above reasons, the development of improved analytical techniques is highly required and NMR is one of the most promising analysis tool in this field. Herein, we report a NMR investigation of the structure and properties of LiPF6-salt solutions based on ternary (ethylene carbonate (EC), diethyl carbonate (DEC) and trimethylphosphate (TMP)) electrolyte solvent mixtures for lithium-ion battery applications. The approach consists of the use of the internally referenced diffusion-ordered spectroscopy (DOSY) method. Solvent coordination ratio, cation valence number as well as self-diffusion coefficients have been thus analyzed upon the different (EC+EDC+TMP) electrolyte formulations and compared with electrochemical measurements.

Resume : Rechargeable seawater batteries have recently been developed by our group as low-cost, eco-friendly energy storage systems, utilizing naturally abundant seawater as the active material in a flow-type, open-structured cathode. The batteries are composed of anode and cathode compartments that are separated by a Na-ion conducting ceramic electrolyte (Na3Zr2Si2PO12), which allows only Na ion transport between the two compartments. The batteries are charged and discharged based on the redox reactions of seawater at the cathode side and of Na ions at the anode side. In this work, we studied ‘anode-free’ seawater batteries, which use only seawater containing Na ions (approximately 0.5 M) as the active material without the use of anode material. To this end, we modified the anode components of seawater batteries, such as current collector and organic electrolyte, so as to improve the reversibility of Na metal plating/stripping at the anode side. Through comparative studies using carbonaceous current collectors and organic electrolytes containing NaPF6 or NaCF3SO3, we cycled anode-free seawater batteries stably with high coulombic efficiencies, demonstrating the utility of battery system exploiting only natural seawater as the active material.

Resume : Electrical properties of fast Li conductor Lithium Lanthanum Titanate (LLTO) ceramics were studied at broad frequency (1 Hz÷10 GHz) and temperature (190÷1280 K) ranges. The obtained results allowed accurate determination of the specific conductivity of ceramic grains, which were found to reach 30 S/m at high temperatures. A strong deviation from Arrhenius law was observed by continuously decreasing activation energy of conductivity at temperatures T>400 K. Completely unexpected result - positive temperature coefficient of resistivity (TCR) at T>1100 K was also observed. Positive TCR would be highly desirable in many electrochemical devices, since it would create negative temperature feedback in devices with ohmic heating. These phenomena may be related to the alteration of the conditions for concerted migration of Li ions and to the alteration of the occupancy of A positions by La in La-enriched and La-depleted planes of the crystal LLTO lattice.

Resume : Attributed to the stable physical /chemical properties and versatile applications, multi-element oxide materials have played an important role in secondary-batteries and storage devices. In this work, cobalt-based multi-element oxide was used according to the Hume-Rothery rule and the Gibbs free energy rule to be fabricated via a standard solid-state ceramic process. By varying the molar ratio of metal oxide elements and ceramic processing conditions, different phases of cobalt-based multi-element oxides were formed and characterized to study their potential applications in lithium-ion batteries. The cobalt-based multi-element oxides were prepared as powders by solid-state ceramic process. After preparation, we used the scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDX), X-ray diffraction (XRD), and the transmission electron microscope (TEM) to characterize the material. The cobalt-based multi-element oxide powders were fabricated into as an anode material for lithium-ion batteries. The fabricated batteries were characterized by galvanostatic charge-discharge (GCD), cyclic-voltammetry (CV) and electrochemical impedance spectroscopy (EIS) analyses. It is expected the novel multi-element oxide materials can improve the performance of lithium-ion batteries and be applied on other storage devices.

Resume : Scientists have for decades been searching for a useful polymer electrolyte system for lithium batteries, which would render batteries where the superior capacity of lithium metal could be used safely. This pose several questions on polymer properties such as amorphicity, polymer mobility, ion coordinating capabilities and the molecular structure of the polymer host. Here, we focus on polycarbonates, the polymeric equivalent of the solvents widely used in liquid electrolytes today, and we especially investigate the influence of side chains. Will the increased molecular mobility (and lowered glass transition temperature) that comes with the addition of side chains increase the ionic conductivity, or will the side chains hinder the transport of ions along the molecule? A low-molecular-weight poly(trimethylene carbonate) was synthesized and compared to polymers containing the same backbone but having side chains with or without lithium-coordinating properties. The total ionic conductivities were compared in relation to the glass transition temperature, and these experimental results were correlated to results from molecular dynamics simulations. Results show that the polycarbonate free from side-chains has the highest ionic conductivity despite having the highest glass transition temperature, owing to that the side chains sterically restrict the movement of lithium ions along the polymer backbone.

Resume : The compounds with polyanionic groups are known to be potential cathode active materials for lithium ion batteries due to their ability of lithium ion insertion. Olivine structured LiFePO4 (LFP) has received a great attention as a cathode active material because of low cost, low toxicity, high thermal stability, and high specific capacity. However, the electrochemical performance of LFP is known to be severely restricted by low lithium ion conductivity, which is attributed to the one dimensional diffusion of lithium ions in the olivine structure. In the present study, we attempted to control the crystal orientation of LFP using a strong magnetic field to enhance the lithium ion transport. We examined the magnetism and magnetic susceptibility of LFP, which are closely related to the crystal rotation in an external magnetic field, and considered how to use these properties for desired crystal alignment. Single cells consisting of the aligned LFP and commercial graphite were fabricated for a galvanostatic charge/discharge test. The cells with the aligned LFP recorded higher capacity than those with the pristine LFP by ca. 10%. The one dimensional delithiation/lithiation should be optimized in the aligned LFP, thus affording the enhanced capability of lithium ion transport. This enhancement decreased the overpotentials during a charge/discharge process; thus, the cells with the aligned LFP consistently exhibited superior capacity to those with the pristine LFP.

Resume : NiSe-Se nanotubes grown on Nickel foam support as a highly conductive electrode material for Asymmetric Supercapacitor Highly conductive Nickel Selenide nano structures were grown on Nickel Foam via a facile synthesis route to form NiSe-Se@Ni Foam by using Chemical bath deposition (CBD) method. The as synthesized highly conductive electro-active material was used as a positive electrode in the fabrication of high density asymmetric supercapacitor. The uniformly grown hollow nanotubular morphology along with their high density packing resulted in large electro-active sites and higher charge transport due to easier diffusion of electrolytes along the surface of the nano structures. the unique lily- like hollow morphology has not been reported in any literature till date to the best of our knowledge. Furthermore, an asymmetric supercapacitor device was assembled using NiSe-Se@Ni foam as the positive electrode and activated carbon as the negative electrode. The specific capacitance of NiSe-Se@Ni foam was found to be 3456 F/g at a current density of 1A/g. The obtained value is twice the value of the earlier reported specific capacitance values from similar NiSe materials. The material maintained a capacitance retention of 73.49% at the end of 2000 cycles. Assymetric supercapacitors help in achieving high energy density without compromising with the high power delivery. Asymmetric supercapacitors(ASCs) consists of of two different electrode materials with the objective of increasing the energy density by expanding the voltage window over a wide range . In ASCs the cathode is made up of one battery-type electrode and anode is made up of a capacitor –type electrode. The reason for selecting Nickel selenide as an electroactive material could be attributed to the following reasons given below. Firstly Selenium has higher conductivity in comparison to oxygen or sulphur which are lower members of the group from the same oxygen family. Conductivity is definitely a very important property essential for an element to be considered as an electrode material. Secondly the small electronegativity of Selenium enables it to retain the morphologies and retain long cyclabilities and rate performance. Moreover the area of NiSe as supercapacitors has not been fully explored like NiO and NiS which further gave us impetus to throw some light on synthesis of novel porous morphologies of Nickel Selenide. In our wok we present for the first time novel and scalable method for the synthesis of NiSe-Se@Ni foam using Chemical Bath Deposition(CBD) which is not only a convenient method but also economical. Thus, the NiSe-Se@Ni foam can be used as a potential positive electrode material for high-performance Assymetric supercapacitor.

Resume : Advanced energy materials and effective manufacturing facilities of battery cells production are key parameters to overcome the economic barrier to entry into the market. This paper reviews the advances that are obtained on new materials for high energy density thin film electrodes based on silicon. These new materials have the capability of keeping an excellent performance of energy storage system, e.g. of lithium ion batteries and beyond, for vehicles and stationary applications. An ordered mesoporous Metal/Metal-Silicon as anode material with integrated current collector is addressed. It will be demonstrated how it is possible to develop a Si based anode material with outstanding properties with one order of magnitude higher capacity than the standard of the day, compatible to many variants of lithium cells, solvents free, cost-effective and capable to be integrated on roll-to-roll processing. Finally, the strong development of an aluminum based battery is represented by reporting our research activities in order to fabricate an aluminum battery linked to roll-to-roll manufacturing method.

Resume : In this study, Ni0.83Co0.12Mn0.05(OH)2 precursor was synthesized using the co-precipitation. Ni-rich system Li[Ni1-x-yCoxMny]O2 have receiving attention as cathode material for lithium secondary battery due to low cost and high discharge capacity. However, the cycle performance decrease because structural instability such as phase change resulted from the Ni content increases. [1,2] In order to improve the cycle performance, we had doped cation that has high binding energy. The cation doped materials were investigated the structural and electrochemical properties. Scanning electron microscope (SEM), X-ray diffraction (XRD) was used to examine the structure, morphology respectively. Then we analyzed electrochemical properties by electrochemical impedance spectroscopy, charge-discharge test. Keyword: Ni-rich cathode material, cation doping Acknowledgement This study was supported by the granted financial resource from the Ministry of Trade program of the Industry & Energy, Republic of Korea (G02N03620000901). References [1] S. W. Cho, J. H. Ju, S. H. Ryu, and K. S. Ryu, J. Korean Electrochem. Soc. 13 (2010) 264. [2] D. H. Kang, N. Arailym, J. E. Chae, and S. S. Kim, J. Korean Electrochem. Soc. 16 (2013) 191.

Resume : Metal oxides (MOs) have attracted vast interest in lithium-ion batteries over past years attributed to their appealing properties such as earth abundant, high theoretical capacity and high stability. In this work, silicon-based multiple element oxides were prepared by ceramic process. By varying the molar ratio of each oxide element, the performance of different lithium-ion batteries fabricated by silicon-based oxide material was investigated to study the relationship between the composition of silicon-based oxide anode materials and performance of lithium-ion batteries. The morphology, composition, and structure of the silicon-based oxides were characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDX), and X-ray diffraction (XRD), respectively. The performance of fabricated batteries was investigated by Galvanostatic charge-discharge (GCD), Cyclic-Voltammetry (CV), and Electrochemical impedance spectroscopy (EIS) analyses.

Resume : Layered LiMO2 (M = Co, Mn, Ni, Fe etc.), especially LiNixMnyCozO2 (LNMCO) are still among the most exploited electrode materials for commercial rechargeable Li-ion batteries. Unfortunately, they suffer from high cost and toxicity due to Co as well as poor thermal stability due to Ni.[1] To overcome these issues, Mn-based oxide materials are receiving significant attention during the last decade due to the low cost and toxicity of Mn and the discovery of manganese oxides with specific capacities ≥ 250 mAh g-1.[2] In this work, an amorphous ramsdellite-like MnOx have been synthesized using low-temperature hydrothermal synthesis. Surprisingly, the amorphous material exhibits good electrochemical performance as Li-ion cathode as opposed to the crystalline phases obtained from similar synthesis. We have investigated the structural and compositional details about the amorphous phase as well as gained insight into the Li-ion intercalation mechanism. This was achieved by electrochemical characterization (CCCV at different C-rates) and Pair Distribution Function (PDF) analysis both under ex situ and operando conditions. [1] M. Armand, et al., Nature, 2008, 451, 652. [2] J. Lee, G. Ceder et al. Nature 2018, 556, 185-190.

Resume : Self assembled hierarchical nanostructures are slowly superseding most conventional nanostructures for use in supercapacitor electrodes. These morphologies intrinsically show high surface area, tunable porosity and packing density. Therefore, modification in the physio-chemical properties can be easily obtained. Modulating the interfacial interactions and subsequent particle assembly, occurring at the interface of the water-and-oil interface in inverse miniemulsions, are amongst the best strategies to stabilize hollow nanostructures. In this paper, we will present the formation of Ce1-xCuxO2 (0

Resume : Two self-assembled Re(I)-based trigonal metalloprisms possessing redox-active ligands e.g. 2,4,6-tris(4-pyridyl)-1,3,5-triazine (tpt), furan-2-methanthiol (for 1) and 2-hydroxymethylanthraquinone (for 2) were studied In spite of similar composition, structure and redox sites, the spectroelectrochemical properties were found to be entirely distinct. One electron reduction of 1 leads to the through space inter-valence charge transfer transitions (IVCT) between the two triazine components of the tpt ligands. This transition results in a broad and high intensity band in the NIR region band. On the hand, no such IVCT band was observed during first reduction of 2. The site of reduction processes observed in the cyclic voltamogram of metallacycle 2 was confirmed by UV-vis-NIR spectroelectrochemical measurements. Similar to metallacycle 1, the first reduction is accompanied by the appearance of absorption bands at around 740, 850 and 960 nm. Similar absorption profile was observed for metallacycle 2 which can be easily assigned to the tpt centered radical anion generation. This band intensified on further reduction which confirmed that these reduction events are occurring at the tritopic tpt ligands. Interestingly, on one electron reduction, the usual absorption bands of the tpt-based radical anion are also accompanied by the emergence of a broad intense band in the NIR region which originates around 1200 nm and extends till 2400 nm. This absorption band is observed only for the singly reduced species and not for the neutral complex. The intensity of this band started to reduce upon second reduction. However metallacycle 2 is comprised of similar tpt ligands, no such NIR absorption signatures were observed in any of the reduction processes.

Resume : LTO (Li4Ti5O12) has been highlighted as anode material for next-generation lithium ion secondary batteries due to advantages such as a high rate capability, excellent cyclic performance, and safety. However, the generation of gases from undesired reactions between the electrode surface and the electrolyte has restricted the application of LTO as a negative electrode in Li-ion batteries in electric vehicles (EVs) and energy storage systems (ESS). As the generation of gases from LTO tends to be accelerated at high temperatures (40–60 °C), the thermal stability of LTO should be maintained during battery discharge, especially in EVs. To overcome these technical limitations, a thin layer of Al2O3 (~2 nm thickness) was deposited on the LTO electrode surface by atomic layer deposition (ALD), and an electrochemical charge-discharge cycle test was performed at 60 °C. The capacity retention after 500 cycles clearly shows that Al2O3-coated LTO outperforms the uncoated one, with a discharge capacity retention of ~98%. TEM and XPS analyses indicate that the surface reactions of Al2O3-coated LTO are suppressed, while uncoated LTO undergoes the (111) to (222) phase transformation, as previously reported in the literature

Resume : Preparation of lithium conducting electrolyte films are of special importance for solid state Li batteries. Among Li conducting solid electrolytes, the ceramics of La0.57Li0.33TiO3 (LLTO) perovskites have received special attention, because of its high grain conductivity at room temperature (0.1 S/m). The aim of this work is the preparation of LLTO thick films by tape casting on insulator substrates or free standing. The microstructure characterization of the prepared thick films has been performed by SEM. The electrical properties were investigated by impedance spectroscopy at broad frequency (1 Hz-10 GHz) range. Total and bulk conductivity will be compared with that reported in ceramics of the same composition.

Resume : A facile chemical vapour deposition method for synthesis of carbon nanospheres (CNSs) is reported here. In this work, CNSs have been synthesized by using benzene as a carbon precursor. A wet chemical process is used here for the synthesis of metal oxide-carbon nanospheres composite. Henceforth, morphology of as-synthesized sample is characterized using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). EDX and FTIR are further used to determine the elemental composition and the presence of chemical bonds on the surface of synthesized material. Raman spectroscopy and X-ray diffraction are used here to determine the crystal structure and phase purity. Electrochemical properties of as-synthesized materials are investigated using cyclic voltammetry and chhronopotentiometry. Metal oxide-CNSs nanocomposite shows higher specific capacitance and good stability, which confirms that synthesized nanocomposite can be used as a electrode material for supercapacitor application.

Resume : Thin films of the lead-free Na_xK_(1-x)NbO_3 (NKN) compound have been intensively researched due to their good ferroelectric parameters and their environmentally friendly characteristics. In addition, due to the very large dielectric constant, it might be a candidate for so-called supercapacitors. Here we focus on the change of optoelectronic properties of NKN films in the amorphous-to-microcrystalline transition region at deposition temperatures between 450 and 600 oC. Film growth was performed by pulsed laser deposition method (PLD), ablating sintered targets by the ultraviolet line of a Nd:YAG laser system at an energy density of about 0.1 J/cm2. The typically 200 nm thick films were then analyzed by scanning electron microscopy (SEM), Rutherford backscattering (RBS), optical transmittance (OT), spectral ellipsometry (SE), Raman spectroscopy, capacitance-voltage characteristics (C-V), and impedance spectroscopy. Low-temperature films showed high surface roughness and poor ferroelectric properties as measured by hysteresis loops. For high-temperature films (600 oC) the SEM micrographs showed clear microcrystalline features of typically 50-100 nm size. Good stoichiometry was verified by RBS. The optical bandgap obtained from SE was 3.69 eV, in accordance with optical transmission results. Best film parameters so far were a dielectric constant of 1.300, remnant polarization 6 microC/cm2, and coercive field of 24 kV/cm.

Resume : The conductive polymer hydrogel, owing to its excellent electrochemical properties and flexibility, is a promising flexible electrode material. However, the poor mechanical properties of conductive hydrogels cannot meet the requirements of flexible supercapacitors as electrode materials. To overcome the drawback mentioned above, conductive polypyrrole (PPy) hydrogels with nanostructure were prepared via an interfacial polymerization method. The synthesis process was simple and endowed the conductive hydrogel with tunable nanostructures and electrochemical performance. Moreover, due to the polymer nanosphere incorporated into the interconnected porous nanostructure, exhibited impressive mechanical properties and high performance applied as supercapacitor electrodes (specific capacitance 368 F g-1). The symmetric solid-state supercapacitor assembled by possesses PPy hydrogels can yield a good energy density of 4.56 Wh kg−1 and a high power density of 0.29kW kg−1. This paper is funded by the International Exchange program of Harbin Engineering University for Innovation-oriented Talents Cultivation.

Resume : The demand for renewable energy generation and electric mobility is growing the need for high capacity and safe energy storage systems. Lithium (Li) metal with ultrahigh capacity (3860 mAh/g) is an ideal metal anode1. However, safety hazards due to formation of Li dendrites and high reactivity has prevented its commercialization2,3. Besides the dangerous Li dendrites, safety concerns courtesy of toxic and flammable organic electrolytes, high manufacturing costs, and weight additions for controlling the thermal events are among other challenges of Li batteries. Therefore, safe operation of batteries in water-based electrolytes is considered a long-term solution. Zn metal is the ideal anode material for aqueous battery systems due to its high theoretical capacity (820mAh/g), high abundance, low toxicity and safety4. Nevertheless, dendritic electrodeposition of Zn metal should be addressed prior to commercialization of these batteries. In this study, we have successfully tuned the morphology of Zn electrodeposits by altering the surface structure of the current collector substrate in Zn-based batteries. We have shown that two dimensional graphene can significantly alter the vertical and dendritic growth of Zn, forming highly lateral Zn hexagons. Utilizing various microscopy and electrochemical techniques we have concluded that graphene not only provides a homogenous Zn-ions nucleation, but also regulates the growth orientation of the final deposition products. The mechanism for this unique structural modification is under investigation by means of various experimental and computational techniques. We believe that our work can trigger novel surface engineering approaches for commercially viable Zn-metal batteries.

Resume : Aqueous rechargeable lithium-ion batteries (ARLBs) have appeared to be a promising candidate for increasing battery safety and reducing fabrication cost. One of such systems was published in 2015 [1], where zinc (Zn) foil had been chosen as a negative electrode due to its abundance in the Earth's crust and high theoretical capacity. However, Zn-based battery systems have a common serious issue arising from the Zn dendritic growth on the surface of the electrode after several cycles leading to shortened cycle life [2]. This problem arises from the Zn dendrite formation on the electrode surface after several charge/discharge processes that leads to short-circuiting of the battery. There are many approaches for suppression or elimination of Zn dendritic growth. This work focuses on the study of Zn dendrite formation in LiFePO4//4 M ZnCl2 + 3 M LiCl//Zn aqueous battery system and on its suppression. This research was supported by the research grant No.AP05136016 “Zinc based Rechargeable Aqueous Battery: A green, safe and economic battery for Space Applications (ZRABS)” from the Ministry of Education and Science of the Republic of Kazakhstan. [1] Yesibolati, N., et al. (2015). Electrochimica Acta, 152, 505-511. [2] Caldeira, V., et al. (2017). Journal of Power Sources, 350, 109-116.

Resume : Si-based thin film is a promising candidate for anode material for Li-ion batteries due to its high theoretical capacity of 3700 mAh/g, low potential vs. Li+/Li. Flat Si thin films with thickness more than 200 nm show a rapid capacity fade due to film delamination from current collector and further electrical contact loss. 3D structure of Si anode can decrease the film damage. Developing of 3D structure for Si material is doomed to failure because in case of significant volume change any patterns experience destruction upon long cycling. Deposition of Si film on 3D current collectors is able to solve the issues with expansion more effectively. The small addition of carbon (C) can positively effect on the electrical conductivity and mechanical stability of the Si-based anodes. Herein, it is reported on facile and cheap venue to prepare well working Si and Si/C thin film anodes with their comparison. Present work performs the study of the electrochemical performance of the Si-based thin film anodes prepared by means of magnetron sputtering. 3D copper substrate prepared by etching in ammonia solution and used as current collectors for Si thin film. The structural changes of amorphous Si-based thin film anodes upon lithiation were studied in-situ. The doping effect on the electrochemical performance of Si film anode was studied with undoped and n-/p-type doped samples. The influence of vinyl carbonate electrolyte additive demonstrated the improvement of the cell performance. All electrochemical cycling test results, as well as synthesis routes and characterization details, will be presented at the conference.

Resume : The never ending need of clean and renewable energy requires the development of more advantageous Al batteries. In our research work using density functional theory calculations, we target to improve the Al battery performance by designing potential cathode materials. We have analyzed various cathodes with different electronic structures and dimensions such as graphite, BC3, carbon nanotubes (CNT), and C3N. The three dimensional layered structure of graphite and BC3 follow staging mechanism to reversibly intercalate/deintercalate the anion AlCl4- into their interlayer galleries offering 2.0 and 2.4 V voltage, respectively but require activation of partially closed galleries to insert large sized AlCl4- anions. The low dimensional materials such as CNTs can overcome this limitation and also improve the capacity (275 mAh/g) of Al batteries. The comparative study of monolayer, bilayer and bulk C3N systems shows that voltage is inversely related to the stability of AlCl4-intercalated system. Here, we conclude that the low dimensional electron-deficient systems having adequate stability towards AlCl4- intercalation will be superior choice to obtain high voltage in Al batteries. (1) P. Bhauriyal, A. Mahata, B. Pathak, Phys. Chem. Chem. Phys. 2017, 19, 7980. (2) P. Bhauriyal, A. Mahata, B. Pathak, J. Phys. Chem. C 2017, 121, 9748. (3) P. Bhauriyal, A. Mahata, B. Pathak, Chem. Asian J. 2017, 12, 1944. (4) P. Bhauriyal, P. Garg, M. Patel, B. Pathak, J. Mater. Chem. A 2018, 6, 10776.

Resume : Organic molecules are emerging candidates for the next generation of cost-effective active materials of Li-ion batteries. Small diimide building blocks such as pyromellitic diimide (PMDI) have attracted much attention due to their high theoretical capacity. Many strategies have been undertaken to limit the well-known phenomenon of dissolution of the active mate-rial in the electrolyte. Such strategies include the preparation of salts and the synthesis of polyimides or macrocycles. Since dibromopyromellitic dimiide exhibits almost no sp2 cross-coupling polymerization reaction by conventional synthetic routes (Suzuki-Miyaura or Migita-Stille), we used PMDI as an aromatic C-H bond-bearing unit for direct (hetero)arylation polymerization (DHAP) with 1,4-dibromobenzene as comonomer as a new stabilization strategy. DHAP proved to be an effective tool in the preparation of this polymer, yielding a number average molecular weight of up to 31 kDa. We studied the effect of side-chain engineering using variable chain lengths, cross-linked structures and thermocleavable functional groups. Practical potential limits of 1.65 to 2.50V vs. Li/Li+, wherein two distinct redox phenomena appear, and a galvanostatic high rate limit of 2C were determined. Galvanostatic measurements at C/20 show a starting normalized capacity of 0.94 decreasing to 0.48 after more than 80 days (50 cycles). A maximum discharge capacity of 73 mAh/g as a first cycle was obtained for a polymer of this family at C/10. Density functional theory calculations were applied to understand the higher corrected redox potentials obtained by cyclic voltammetry for sodium ion over lithium ion batteries.

Resume : Among the anode materials for Lithium-ion batteries (LIBs), LTO [1] and Si [2] are extensively studied for the use in applications which require high power. LTO is commercialized as an alternative to graphite because of its high safety and its ability to be used in high-power devices, due to the “zero strain” of the LTO spinel structure [1]. Si has many advantages when used as an anode material; however, there is a huge volume expansion that should be eliminated. As a possible solution of the stated issues, LTO-matrix might be used as a retaining material in case of the volume expansion of the Si nanoparticles. Until now, a few works on LTO/Si composite anodes were reported. Lin et al. [2] reported the LTO coated with thin film of silicon, and Chen et al. [3] prepared a composite with LTO, Si and conductive carbon. Since both LTO and Si have a low electronic conductivity, the LTO/Si system requires a conductive connecting agent/network to allow for efficient lithium ion diffusion. Cyclized polyacrylonitrile (c-PAN) is a polymer consisting of a conductive network of fused pyridine rings, and it was widely combined with silicon to form efficient composite anodes for LIBs [4]. This work describes the development of the new preparation technology of the anode composite material, which is based on LTO spinel and Si with addition of PAN, which demonstrates a synergistic positive effect on the performance of LIBs. This system is considered as promising alternative for the potential application in electric vehicles, energy storage systems for renewable energy sources and many others. 1) F. Luo, B. Liu, J. Zheng, G. Chu, et al., Nano-silicon/carbon composite anode materials towards practical application for next generation Li-ion batteries, J. Electrochem. Soc. 162(14) (2015) A2509–A2528. 2) Y. Lin, Y. Yang, Y. Lin, G. Zhao, T. Zhou, Z. Huang, Effects of amorphous silicon film on elevated-temperature cycle performance of Li4Ti5O12 for lithium ion battery, Int. J. Electrochem. Sci. 6 (2011) 5588–5596. 3) C. Chen, R. Agrawal, C. Wang, High Performance Li4Ti5O12/Si composite anodes for Li-ion batteries, Nanomaterials 5 (2015), 1469. 4) F.M. Hassan, R. Batmaz, J. Li, et al., Evidence of covalent synergy in silicon–sulfur–graphene yielding highly efficient and long-life lithium-ion batteries, Nature Comm. 6 (2015) 8597.

Resume : As lithium secondary batteries have been recently applied to greater power sources, it is essential to increase the batteries’ energy density. The energy density can be simply enhanced by increasing the loading amount of an electrode active material; however, the transport of lithium ions can be impeded in the charge/discharge process, resulting in the serious decrease in current output. In the present study, we adjusted the crystal orientation of an electrode active material by using a strong magnetic field, thus minimizing the loss of lithium ion transport despite the high loading amount of the material. We observed the magnetic properties of LiCoO2 (LCO), which is the most representative commercial cathode active material, and considered how these properties work on the crystal alignment of LCO; thus, we established the theoretical process of crystal alignment using a magnetic field to prepare an crystal-aligned LCO. Half cells consisting of the aligned and pristine LCOs were individually fabricated for a galvanostatic charge/discharge test. The cell with the aligned LCO recorded a higher capacity than that with the pristine LCO by approximately 20%. The direction of lithium ion transport should be ideally adjusted in the aligned LCO, and thus the capability of lithium ion transport is expected to improve. This improvement should decrease the overpotentials during a charge/discharge process, thus affording the dominant capacity of the aligned LCO.

Resume : Na ion batteries have received a lot of interests due to its significant and well dispersed reserves compare to Li ion batteries. However, the graphite, a most representative anode material in Li ion batteries, is not compatible in Na ion batteries, and it led us develop new anode materials. Among the candidates of new anode materials for Na ion batteries, hard carbon is considered a one of most promising anode materials. Despite of this popularity of hard carbon, there is a significant debate on Na insertion mechanism in hard carbon and improvement of capacity is highly needed. Many researches have tried to increase capacity of hard carbon by modification of hard carbon. However, in most studies, the capacity at high voltage region has increased, not as a capacity enhancement in low-potential region which is attractive as a battery anode material. [1] Besides, capacity increase in low potential region from biomass derived hard carbons, however, causes of capacity enhancement is unclear due to complexity of biomass derived hard carbon materials. [2] Recently, Ji Xiulei et al. reported high capacity hard carbon utilizing low potential region by using sucrose, graphene oxide and phosphoric acid. However, role of phosphoric acid in hard carbon is still unclear and its sodium storage mechanism should be more clarified. [3] Therefore, we tried to investigate effect of phosphoric acid and graphene oxide to understand additional sodium storage mechanism. In this study, the mechanism was comprehensively analyzed through electrochemical and spectroscopic methods. This study is thought to be helpful for designation of high capacity hard carbon using phosphoric acid. References [1] Z. Li et al., Chem. Mater., 2018, 30, pp 4536–4542 [2] E. M. Lotfabad et al., ACS Nano, 2014, 8, pp 7115–7129 [3] Z. Li et al., ACS Energy Lett., 2016, 1, pp 395–401

Resume : The growing demand for energy storage in society makes it necessary to explore alternatives to traditional lithium-ion batteries and sodium ion battery (SIB) is a promising candidate. So far, due to the incompatibility of graphite with SIB, SIB system needs to develop new anode materials. Herein, we suggested a new material, the titanium silicate material Na2Ti2O3SiO4·2H2O (STOS) as the electrode material of SIB. This material is synthesized by hydrothermal method and has a relatively stable capacity. [1] Moreover, after removing the crystal water from the STOS lattice, we demonstrated that the performance of batteries has been enhanced by spatial improvement. [2] The kinetic properties and reversibility of sodium ions battery is significantly improved after positional constraints of sodium ions and degradation of materials were mitigated. Further, based on this method, the study investigated effect of crystallization water on the reaction mechanism of STOS minerals. We estimate that similar enhancements also could be applied to others electrode materials which containing electrode water to achieve potential capacity and performance improvements. References [1] N. A. Milne et al., Chem. Mater., 2006, 18, 3192-3202. [2] G. J. Thorogood et al., Chem. Mater., 2010, 22, 4222-4231.

Resume : Energy storage has been attracting a lot of attention over the past decade, because it is essential for many applications such as portable electronic devices and electric vehicles. Lithium ion batteries (LIBs) are among the most successful device technologies in this field. But LIBs are becoming the bottleneck in technology development, because the improvement of the specific capacity of electrodes, cycle life of the battery and charge-discharge speed are behind the targeted requirements of devices nowadays. Niobium tungsten oxide (NbWO), a new material system proposed very recently, has been attracting attention due to its stable host structure for lithium intercalation and diffusion. The first report suggests that because of its suitable crystal structure, nanoscaling and nanostructuring is not needed in this type of electrode. In our study, we carried out a detailed electrochemical study on the Nb18W16O93 electrode to understand the lithium insertion process better, and to determine whether the grain size affects the electrochemical behavior of the electrode. In the detailed Cyclic Voltammetry (CV) with varied voltage range, the results reveal a suitable voltage range of 1.5-3.0V for the reversible lithiation during the charge-discharge process for Nb18W16O93 electrode. The rate performance and capacity as a function of grain size will also be reported.

Resume : Hydrous RuO2 has been one of the well-studied materials for application in supercapacitors owing to its excellent properties (high conductivity similar to metals, redox active Ru4+ ion capable of fast faradaic reactions and structural water enabling swift proton transfer and decreased diffusion distance). However, for high power/energy density micro-supercapacitors, it’s necessary to have economic strategies for controlled deposition of thin films of hydrous RuO2. One win-win strategy has been to construct 3D scaffolds which can hold small quantities of intrinsic pseudocapacitive materials like RuO2, thereby decoupling the direct relationship between power and energy density. Hence, it is essential to develop new techniques to achieve novel 3D structures under ambient conditions which can provide extremely high surface area. The challenge is also magnified in such a scenario, needing controlled decoration of active materials on for efficient utilization and full benefit of the 3D framework. Hence, the pursuit of superior micro-supercapacitors not only needs controlled deposition, but also requires stable 3D scaffolds to maximize capacitance per footprint area. In the current work, we report nanometer scale control over thickness of hydrous RuO2 by utilizing optimized conditions. We also report successful fabrication of highly porous 3D platinum current collector using dynamic hydrogen bubble template (DHBT). The synergistic utilization of these two concepts can thus be perfect stage for fabricating superior micro-supercapacitors with excellent capacitance and low internal resistance.

Resume : Materials with tailored properties are crucial for high performance electronics applications. Hybrid materials composed of inorganic and organic components can possess unique merits for broad application by synergy between the advantages the respective material type offers. Here we demonstrate a novel electrochemical polymerization (EP) enabled by a 2D transition metal carbide MXene for obtaining conjugated polymer-MXene composite films deposited on conducting substrates without using traditional electrolytes, indispensable compounds for commonly electrochemical polymerization. The universality of the process provides a novel approach for EP allowing fast facile process for obtaining different new polymer/MXene composites with controlled thickness and micro-pattern. Furthermore, high performance microsupercapacitors and asymmetric microsupercapacitors are realized based on the novel composites benefiting from higher areal capacitance, better rate capabilities and lower contact resistance than conventional electropolymerized polymers. The excellent electrochemical properties of the composite polymerized with MXene suggest a great potential of the method for various energy storage applications.

Resume : The changing landscape of energy conversion towards more electrification requires new solutions for energy storage which safely deliver high power and can withstand large number of charge/discharge cycles. Supercapacitors, unlike Li-ion batteries, can provide such benefits, however, they face challenges in specific energy, self-discharge, and cost. Li-ion capacitors are a hybrid energy storage solution that combines the advantages of supercapacitors and Li-ion batteries. In this work, we demonstrate how Li-ion capacitors can achieve high specific energy and high specific power through the utilization of an amorphous n-type silicon nanoparticle–based anode in combination with an activated carbon cathode. Amorphous n-type Si nanoparticles were synthesized through the pyrolysis of silane and an n-type doping precursor. The formation of nanoparticles can be controlled by temperature of the pyrolysis and silane/dopant ratio. Using silicon expands the voltage window, thus improving specific energy, and reduces self-discharge. The amorphous nanoparticle structure improves pre-lithiation, cycle life, and rate capability, which itself is further enhanced by doping to reach a specific power similar to that of supercapacitors. Using conventional slurry casting, the n-type silicon anode delivered 16 times the normalized capacity of undoped silicon at 5 mA/cm2 despite having 1.8 times the loading, and withstood 5500 cycles with no degradation in capacity in a full cell.

Resume : Electrospinning is an efficient technique to produce ultrafine electroactive mat diameters ranging from few nanometers to micrometers for a separator in sodium ion battery application. The effects of polymer concentration, applied voltage, flow rate and the addition of acetone to the polymer solution were investigated with the morphology and fiber diameter of the polyvinylidene fluoride (PVDF) mats. The polymer solution is optimized to 18 wt.% voltage 20 kV and flow rate 0.5 ml h-1 to get a bead free ultrafine electroactive structure. The electroactive ?-phase is confirmed by X-ray diffractometer (XRD). The average fiber diameter (AFD) reduced from 700 nm to 314 nm. Ionic conductivities, electrolyte uptakes, linear sweep voltammetry (LSV) and interfacial resistances of the nanofibrous electroactive polymer electrolyte (NEPE) were studied by soaking the membrane separator with a liquid electrolyte solution of 1 M sodium hexafluorophosphate (NaPF6) dissolved in ethylene carbonate (EC)/ propylene carbonate (PC) (1:1, vol.%). The NEPE exhibit high ionic conductivity of 0.98 mS cm-1 and stability window of 5.0 V versus Na/Na+ at room temperature. The half-cell containing Na2/3Fe1/2Mn1/2O2 as cathode and NEPE as the separator cum electrolyte show stable cycling performance at a current rate of 0.1C.

Resume : Redox Flow Battery (RFB) is one of the Energy Storage System (ESS) that converts electrical energy into chemical energy and converts chemical energy back into electrical energy. The RFB has the advantages of high stability and design independence of capacity and power. However, Vanadium Redox Flow Battery (VRFB), which has been actively studied, has difficulties in commercialization because of the high price of vanadium used as active material.  In order to solve this problem, we have studied the system of Alkaline Redox Flow Battery (ARFB) which uses cobalt and iron that has the lower cost than the vanadium as active materials. The metal-ligand complex was prepared by using triethanolamine to convert the transition metal into an active material under alkaline conditions. The complexity of triethanolamine was largely dependent on the ratio of metal to ligand and electrolyte conditions. Therefore, the study was conducted to find the electrolyte condition that can maintain the metal-ligand complex stably. We have found the electrolyte condition that the complex remains stable through the half-cell test, and we performed a full cell test to see if the metal-ligand complex can be used as the active material of the RFB. As a result, the charge efficiency was 94.11 %, the voltage efficiency was 69.03 % and the energy efficiency was 64.98 % at current density 40 mA cm-2. During the charging and discharging, the state of charge was maintained at 89.44 % and the power density was 36 mW cm2.

Resume : Conjugated carboxylate-based materials are considered as the most promising candidate anode materials for organic batteries.[1] In this context, various approaches have been reported in order to improve their electrochemical performance, including aromatic extension for high rate cycling [2] and substituent/heteroatom effect for potential tuning.[3-4] However, engineered molecules also raise questions on the origin of potential shift and redox mechanism. The case of disodium 2,5-pyrazinedicarboxylate [4] is one example, since it merges two intramolecular redox units: the dicarboxylate and the pyrazine. Its unusually high redox potential (1.8 V vs. Li/Li+) triggered our curiosity on which of the redox units is reacting - the dicarboxylate or the pyrazine system? In this work, we compare, analyse and discuss the electrochemistry of a series of aromatic and N-heterocyclic-dicarboxylate structures. Our study comprehends (i) the effect of N-heteroatom on the redox potential of the dicarboxylates, with a direct correlation between the redox potential and the 13C-chemical shift as well as vibration frequency shift of the carbonyl, (ii) the isomeric effect on the electrochemical property of the carboxylate and (iii) the redox mechanism unveiling the structural requirements that dictates the electrochemical activity of either dicarboxylate or the pyrazine redox units. References [1] M. Armand et al., Nat Mater. 2009, 8, 120. [2] L. Fedele et al., J of Mater Chem A. 2014, 2, 18225. [3] a) A. E. Lakraychi et al., J of Power Sources. 2017, 359, 198, b) A. E. Lakraychi et al., Electrochemistry Communications. 2018, 93, 71. [4] X. Wu et al., J of Energy Chemistry. 2014, 23, 269.

Resume : Currently many investigations focus in finding materials suitable as electrodes for the development of high capacity energy storage devices such as Li and Na-ion batteries. To this end germanium nanostructures have been considered as an attractive alternative for anodes due to its high theoretical charge capacity, especially porous Germanium (pGe). However, there are limited investigations in this respect with seldom theoretical studies on the effect of lithium and sodium on the properties of pGe. In this work, the effect of interstitial and surface Na and Li on the electronic properties of pGe is studied using the first-principles density functional theory approach and the supercell scheme. The pores are modeled by removing columns of atoms of an otherwise perfect Ge crystal in the [001] direction, the dangling bonds are passivated with H atoms, and then replaced gradually by Li and Na atoms, also Li and Na are inserted on interstitial positions on the Ge core. The results show that the surface Li introduces trap-like states in the electronic band structures which increase as the number of Li atom increases with a tendency to become metallic. The interstitial Li and Na create effects similar to n-type doping where the Fermi level is shifted towards the conduction band with band crossings of the said level thus acquiring metallic characteristics. These results could be important for the application of pGe nanostructures in ion batteries technology.

Resume : Anodes for Li-ion batteries developed very fast during the past decade and reached high capacities of >1000 mAh/g, became cheap and eco-friendly. On the contrary, inorganic cathodes reached a bottleneck in their development: industrially used materials are not environment-friendly and deliver limited capacities of ~150-200 mAh/g. Organic cathodes represent a very promising alternative due to feasibility of reaching significantly improved capacities of >500 mAh/g for the best materials combined with low cost and environmental safety. The main obstacle for practical implementation of organic cathode materials is their low stability (rapid capacity fading) caused mainly by dissolution of redox-active components in electrolyte during charge-discharge cycling. This problem can be addressed by designing polymeric redox-active materials possessing high molecular weights and low solubility in organic solvents. It has been shown recently that quinizarine is a promising building block for designing polymeric cathode materials for lithium batteries [A. Petronico et al., Adv. Energy Mater. 2018, 8, 5, 1700960]. In this work, we report the synthesis and characterization of novel promising redox-active macromolecules represented by quinizarine-based linear polymers and star-shaped fullerene derivatives bearing multiple quinone units attached to the fullerene cage. Electrochemical characteristics of the designed materials and their performance in metal-ion batteries will be discussed.

Resume : Li4Ti5O12 (LTO) is alternate anode material of graphite, it has a low electronic conductivity and Li-ion diffusion coefficient, limiting the charge/discharge properties at high rate capacities, and also suffers from gassing during cycling caused by electrolyte decomposition owing to interfacial reactions. Surface coating with a conductive carbon layer is widely used to enhance electronic and ionic transport within LTO, significantly improving the electrochemical performance. Such a barrier layer can effectively suppress gassing due to interfacial reactions because during the cycling process, a thick layer of solid electrolyte interface (SEI) is formed on carbon coated electrode, which protect from interfacial reactions of LTO surface with electrolyte. Both the formation and decomposition of SEI layer causes gassing. With increasing the temperature, the SEI layer becomes unstable and started to decompose its carbonate species, which accountable for gassing. Also, the carbon materials have high reactivity with electrolyte solutions at elevated temperatures, which raises safety concerns. Therefore, alternative surface coating layers of inorganic materials have been proposed, such as ZnO, AlF3, NiOx, and TiNx, that have negligible reactivity with the electrolyte. Surface modification of LTO resulted in a smoother and thinner SEI layer. However, LTO electrode coated with these inorganic materials have poor capacity. In this regards, we demonstrate a novel method for decorating LTO with N-doped graphene quantum dots (N-GQDs). We evaluated this material for the proposed application of lithium-ion battery (LIB) anodes. By encapsulation of LTO by N-GQDs, a thin and smooth SEI layer was formed (similar to inorganic coatings) on the surface of N-GQDs-encapsulated LTO. Moreover, the capacity was also improved. Furthermore, N-GQDs protected the LTO from the interfacial reactions with the electrolyte, which resulted in no phase change of the outermost surface of LTO and suppressed the gassing during the cycling process. For the first time, we present an effective strategy for obtaining excellent cycling performance of LTO at high C-rates and a long cycling life. The Li-ion diffusion coefficient was enhanced by ~19% due to the quantum dot charge transfer layer. Excellent specific capacities, the highest among those reported for LTO-based anodes, were achieved. At 50C, the capacity is enhanced by ~23% by encapsulation of LTO by N-GQDs.

Resume : Si-based thin film is a promising candidate for anode material for Li-ion batteries due to its high theoretical capacity of 3700 mAh/g, low potential vs. Li+/Li. Flat Si thin films with thickness more than 200 nm show a rapid capacity fade due to film delamination from current collector and further electrical contact loss. 3D structure of Si anode can decrease the film damage. Developing of 3D structure for Si material is doomed to failure because in case of significant volume change any patterns experience destruction upon long cycling. Deposition of Si film on 3D current collectors is able to solve the issues with expansion more effectively. The small addition of carbon (C) can positively effect on the electrical conductivity and mechanical stability of the Si-based anodes. Herein, it is reported on facile and cheap venue to prepare well working Si and Si/C thin film anodes with their comparison. Present work performs the study of the electrochemical performance of the Si-based thin film anodes prepared by means of magnetron sputtering. 3D copper substrate prepared by etching in ammonia solution and used as current collectors for Si thin film. The structural changes of amorphous Si-based thin film anodes upon lithiation were studied in-situ. The doping effect on the electrochemical performance of Si film anode was studied with undoped and n-/p-type doped samples. The influence of vinyl carbonate electrolyte additive demonstrated the improvement of the cell performance. All electrochemical cycling test results, as well as synthesis routes and characterization details, will be presented at the conference.

Resume : The monoclinic TiNb2O7, was recently introduced as an alternative anode material. TiNb2O7 can theoretically accommodate five Li per formula unit as LixTiNb2O7 (0 < x < 5) via multiple redox couples (Ti4+/3+, Nb5+/4+, and Nb4+/3+), and consequently, has a higher theoretical capacity (388 mA h g-1) than graphite. Moreover, its safety characteristic, related to the prevention of SEI layer formation due to the higher operating potential, is also attractive. However, the intrinsic low electronic conductivity and poor ionic diffusivity in the TiNb2O7 lattice have restricted its electrochemical performance, such as its capacity retention and rate capability. In this study, niobium-based transition metal oxides were synthesized by a solvothermal reaction followed by post-heat treatment at 700 ℃ for use as the first time anode material for lithium-ion batteries. The prepared niobium-based transition metal oxides had the composition of MNb2O6, and Ms are Cu, Zn, and Mn. The crystal structure and microstructure of CuNb2O6, ZnNb2O6, and MnNb2O6 are investigated by XRD, XPS, SEM, and TEM. The electrochemical analysis shows the possibility of anode material of Li-ion battery.

Resume : A carbon-coated Na3V2(PO4)2O2xF3-2x (NVPOF/C) nanoparticle synthesized by a novel pyro synthesis method was used as a cathode material for sodium-ion batteries (SIBs). At 0.1 C, NVPOF/C cathode exhibited a discharge capacity of 130 mAhg-1, corresponding to 100% of the theoretical capacity. Even at 50 C, a discharge capacity of ~85 mAh/g could be achieved. After 500 cycles at 1 C, capacity retention of 87% was obtained. The in-situ X-ray diffraction and ex-situ synchrotron X-ray absorption near edge structure spectroscopy results revealed that the reversible sodium ion insertion/extraction into/from NVPOF/C host structure occurs with a small volume change (3.4%), indicating the structural stability of the cathode. Our study demonstrates that the Na3V2(PO4)2O2xF3-2x/C electrode is a promising candidate for developing high power/energy density cathodes for SIBs.

Resume : Vanadium oxides (VOx) have been extensively investigated as electrode materials for lithium ion batteries owing to their high theoretical capacities and inexpensiveness.1 However, a comparison study of electrochemical behaviors for V2O5, VO2 (B-phase, M-phase and amorphous (AM) phase) and V2O3 under similar conditions is limited. Herein, various VOx/rGO composites have been synthesized via impregnation and hydrothermal methods that require cheap commercial V2O5 as vanadium source, with commercial reduced graphene oxide (rGO) as support. Different oxidation states, crystalline and amorphous phases and nanoscale morphologies have been confirmed by using TGA, XRD, SEM and TEM. The obtained composites are denoted as V2O5@rGO, VO2(B)@rGO, VO2(AM)@rGO and V2O3@rGO. The electrochemical properties were studied using galvanostatic charge-discharge tests in different potential windows and at various current densities for lithium cells. Their sodium storage performance has also been explored. Moreover, the electrochemical behaviors of the VOx/rGO composites are compared to commercial (CM) VOx. V2O5@rGO, VO2(B)@rGO and VO2(AM)@rGO were found to show stable cycling in a narrow potential window of 2.0–3.6 V (vs. Li/Li ). VO2(B)@rGO electrodes retain 96% of the specific capacity after 150 cycles at 100 mA g-1, greatly surpassing the V2O5@rGO electrode. VO2(B)@rGO and VO2(AM)@rGO display similar lithium storage capacities, whereas the potential profiles as well as the cycling stability are markedly different. These composites exhibit very different electrochemical behaviors for sodium storage, with slope potential profiles, and decent capacities can be delivered. Peculiarly, the V2O3@rGO shows no electrochemical activity in a potential window of 2.0–4.1 V (vs. Li/Li ) with a reversible capacity of 291 mAh g-1 attained if the potential extended to 0.1 V. We attribute this contribution from rGO and demonstrate that V2O3 is relatively electrochemically inert. This work could serve as a valuable guide for future development on this class of important battery materials.2 References [1] F. Mattelaer, et al., ACS Appl. Mater. Interfaces, 2017, 9, 13121−13131. [2] X. Liu, et al., in preparation.

Resume : Supercapacitors (SCs), also known as electro-chemical capacitors (ECs), have attracted increasing attention owing to their fast charge and discharge rates, long cycle life and their ability to complement Li-ion and other advanced secondary batteries. Among the various kinds of carbonaceous materials that have been employed to fabricate SCs, the one-atom-thick two-dimensional (2D) sp2 carbon structure of graphene has attracted considerable interest by virtue of the fact that its ideal structure offers a unique combination of good mechanical/chemical stability, high electrical/thermal conductivity, and a large surface area of over 2630 m2 g-1. Especially, due to the high theoretical surface area of single layer graphene, it is expected to have high specific capacitance (550 F g-1) as an electrode material for SCs applications. However, solution processing results in aggregation of graphene nanosheets due to strong van der Waals forces of attraction, leading to lower values of surface area and lesser number of electrochemically active sites thereby giving lower than the theoretically expected value. Therefore, the current status calls for new and innovative strategies to enhance the charge storage properties of graphene-based materials. From this point of view, in this presentation, we report on the strategies to effectively exploit graphene-based electrode materials for supercapacitor applications. More details will be discussed at the meeting.

Resume : Nanostructured ZnO has gained great attention because of its many advantages such as easy to miniaturization and high thermal stability etc. Holey ZnO nanosheets were synthesized via hydrothermal method followed by an annealing process at a different temperature and used for supercapacitor applications. The transformation of shape and size of holes in ZnO nanosheets has been well-controlled using annealing process at 400, 600 and 800 °C. The structure, morphology, and composition have been investigated systematically using XRD, FESEM, TEM and XPS. FESEM and TEM results indicate that pore size (hole diameter) found to altered after annealing process. The pore size is found to be decreased with increasing annealing temperature. ZnO annealed at 400°C shows a highly porous network, owing to its high surface area, exhibits high electrochemical performance. The faradaic reactions taken place on the surface of ZnO@400°C found to increase as compared to increase ZnO@600°C and ZnO@800°C, which is attributed to high surface area. The fabricated holey ZnO@400°C electrodes demonstrated a high areal capacitance of 164 mF cm−2 at scan rate of 20 mV g-1. These holey engineered ZnO nanosheets represent a promising candidate for electrochemical processes and can open up avenues for electrochemical energy storage devices and also for other device applications.

Resume : Considerable research has been devoted to the study of lithium ion batteries (LiBs) in the past decade due to its capacity and other properties to be a high-performance LiB option. Nanocrystalline MoO2 have been studied extensively for use as anode materials to develop high performance LiBs. In this study, we try to synthesize the composites of molybdenum dioxide (MoO2) and molybdenum carbide (MoxC, x=1,2) with ordered mesoporous structure and use this metal oxide and carbide composites as anode materials, which has at least two advantageous features compared to bulk MoO2 or nano-structured MoO2: one is higher stability which can suggest a higher current density to charge and discharge; and the other is higher stability other nano-structured MoO2 to maintain the nano structure. However, the theoretical capacity of MoxC is very low. To solve the problem, doping carbon when synthesize the MoO2/MoxC composite has been adopted to improved capacity of mesoporous MoO2/MoxC anode in LiB. In this study, we have successful synthesized ordered mesoporous MoO2/Mo2C/C with high surface area and crystalline frameworks by using a incipient wetness impregnation method from a mesoporous silica template of KIT-6 and employed as electrode in lithium ion batteries. On the basis of the investigation of the XRD pattern, nitrogen adsorption & desorption (BET), CV curves, galvanostatic voltage profiles, cycle performance, rate performance and electrochemical impedance spectra(EIS),it was found that when the molybdenum carbide-content is 20wt%, the electrochemical properties of meso-MoO2/Mo2C is significantly best.

Resume : In order to meet the demands of the rapidly growing ESS and electric vehicle markets, a high-performance battery system is required especially in view of high safety and rate characteristics. An aqueous rechargeable sodium ion battery (ASIB) seems to be a good candidate based on its advantages of low-cost, safety, and high electrical conductivity. Most developing ASIBs adopt NaTi2(PO4)3 (NTP) as the negative electrode material because of the limited choice for the electrode materials with reasonable redox potential. NTP shows a well-defined redox potential of −0.6 V (vs SHE). However, although NTP is characterized by high Na-ion conductivity with the theoretical specific capacity of 133 mAh/g, its low electronic conductivity causes the low capacity release and the poor cycle stability. Therefore, many previous studies have developed the NTP-carbon composite by coating the NTP particles with the carbon precursor and carbonizing it through the thermal treatment. NTP crystals are usually synthesized in an ethanol-based solution to prevent the production of titanium oxide and the synthesized NTP particles and carbon precursor are sequentially mixed in water-based solution and carbonized. In this study, NTP synthesis and carbon coating are simultaneously performed by a single thermal treatment in the ethanol-based solution.

Resume : Lithium-ion batteries are composed by micrometer sized electrodes and an electrolyte made by a lithium salt dissolved in an organic compound. However, these materials limit the efficiency of those batteries (energy storage and power supply), as well as operation safety; then, to face this problem, was paid attention to the use of nanostructures, which are one of the most promising strategies to manufacture electrodes and electrolyte. Motivated by the possibility of coupling nanostructured systems to design innovative electrochemical systems, stability and chemical nature of the electrode-electrolyte interface were studied: a Ge-NW electrode deposited on a LaTiO3 electrolyte. The study was carried out within the framework of the Density Functional Theory, in the Hubbard corrected local density approximation. Results shown that a deformation of the NWs’ cross-section is a function of its orientation on the electrolyte, regardless the NW’s diameter. On the other hand, due to interactions between the Ge-NWs and the LaTiO3 layer, there are an electronic charge redistribution; then the Ge-NWs with the smaller diameter lose charge at the contact surface. For the larger electrodes case, the electronic redistribution depends on the NW orientation on the electrolyte: Ge-NWs can lose charge either, on their surface or at the center of their cross-section. Also, the smaller size Ge-NWs coupled system behaves as metal while, increasing diameter, the system turn to be a half-metal or a semiconductor, depending on the relative Ge-NW-electrolyte orientation. Acknowledgments: This work was partially supported by project IPN-SIP-2019-6659. J. M. Cervantes and E. Zuñiga acknowledge the scholarship from CONACYT.

Resume : Aqueous rechargeable zinc ion batteries have an energy storage advantage over non-aqueous Li-ion batteries in virtue of their low cost, high safety and durable lifetime nature.1 The desire to explore more high-capability and adequate-lifetime positive electrodes is urgent.2-3 Herein, we reported a stretchable film comprised of MoS2 nanosheets inserted in Polyaniline through a facile solvothermal method. This film was used as the cathode material for a Zn cell. S (99.999%, Alfa Aesar) and Mo (99.999%, Alfa Aesar) were loaded into the stainless steel ballmilling according to the stoichiometric ratio MoS2 in a glove-box under argon atmosphere. Then the jar was milled for 20 h at 1200 rpm. The morphological and structural of MoS2 cathode are studied by field emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD). The cathode serves a dual function: synergistic merits of desirable morphology of MoS2 and ultrahighconductivity enhancers in polyaniline network. Such combination brings unprecedented flexibility and reversibility to Zn batteries in 6M KOH solution. The conductivity of free-standing electrode remained above 120 S/cm under a fracture strain of 400%. The optimal battery exhibits high capacity of 150 mAh g−1 at 1 A g−1 and excellent cycling stability of up to 500 cycles with a capacity retention of 83%. In summary, this work offers insight into the design of organic/inorganic electrodes for energy storage applications ensuring an enhanced cycling stability. References [1] Bruce Dunn, H. K., Jean-Marie Tarascon, Science. 2011. [2] Liang, H.; Ni, J.; Li, L., Nano Energy 2017, 33, 213-220. [3] Ni, J.; Zhao, Y.; Liu, T.; Zheng, H.; Gao, L.; Yan, C.; Li, L., Advanced Energy Materials 2014, 4 (16).

Resume : Supercapacitors have been widely used for many applications, such as electric vehicles, memory devices and renewable energy power systems due to their fast charge-discharge process, high power density, and good cycling stability. Nickel oxide (NiO) films have for a long time attracted attention as pseudo-capacitive electrode materials due to environmental compatibility, low cost and high theoretical specific capacitance compared to conventional materials. However, the rate performance of NiO electrodes remained very low due to intrinsically poor electrical conductivity for supercapacitor application. We present a new method for the enhancement of supercapacitor performance with excellent eletrical properties using Au-NPs-decorated NiO films fabricated by using of simple ion coater. The films had uniformly dispersed Au nanoparticles in the NiO grain matrix. The specific capacitance of the Au-decorated NiO electode was higher than that of the pure NiO electrode. The enhanced electrochemical performance was attributed to the fact that Au addition on the NiO matrix could improve the intrinsic electrical conductivity of NiO, resulting in high specific capacitance in comparison with pure NiO thin film. Our fabrication process and rational design of Au-decorated NiO structures may be extended to improve the intrinsically poor electrical conductivity of electrode materials for electro-chemical energy storage applications.

Resume : Lithium secondary batteries with high energy density have been used as powerful energy storage devices in various applications such as electric vehicles and portable electronic equipment. Recently, as the problem of stability of lithium ion battery using liquid electrolytes emerged, solid-state electrolytes which have high stability have been developing as a solution to solve the problem. However, the low diffusion coefficient of lithium ion in the solid-state electrolytes is a major obstacle to commercialization. Therefore, we need to understand the actual behavior of lithium ion in nano- and micro-scale and design solid-state electrolytes accordingly. Our study uses electrochemical strain microscopy (ESM) as one of atomic force microscopy (AFM) mode, to measure lithium ion concentration of lithium-ion conductive glass-ceramics (LICGC) through ionic movement induced by applied voltage. First, we calibrate quantitatively the lithium ion concentration from the ESM amplitude giving ac voltage to the tip and inductively coupled plasma (ICP) data. Second, we collect lithium ion concentration change at each trench on the sample after applying dc pulse. Based on these data, we use Fick's law to calculate diffusion coefficient with spatial and time resolution. These results are compared with those measured from impedance spectroscopy, which can provide the link between local and macroscopic properties as well as insight into the lithium ion transport mechanisms at the nanoscale.

Resume : In recent time transition metal oxide vanadium pentoxide (V2O5 ) is consider as an excellent energy storage device material for Li-ion batteries (LIBs) with reference to its high charge storing capacity, low cost, rich layered structure and abundant material. With respect to its rich layered structure, which can reversibly accept the intercalation and deintercalation of Li-ions in the process of charging and discharging of LIBs. In this study, we report a simple hydrothermal procedure to synthesize the porous microstructure of V2O5 as a cathode electrode for LIBs with subsequent annealing temperature. The structural analysis stands for the orthorhombic phase of V2O5 and other sub oxides phase of vanadium are absent. The RAMAN analysis justify the layered structure of V2O5. The morphological study of V2O5 shows the flower like three dimensional micro flowers (having diameter ~5µm) self-assembled by Nano rods. In electrochemical cyclic voltammetry measurement three cathodic peaks were observed corresponds to 3.27V, 3.05V and 2.08V as Li/Li+ refers to three crystal phase α-V2O5 to β- Li0.5V2O5; β-Li0.5V2O5 to δLiV2O5 and δ -LiV2O5 to γ –Li2V2O5 respectively, And also three anodic peaks corresponds to Li-ion deintercalation. Which indicate the good reversibility of the electrode. In this report, V2O5 microflowers shows excellent specific discharge capacity of 290mAhg-1 and after 50cycles the capacity reduced to 198mAhg-1, cycled between the voltage range 2.0-4.0V at the current rate 0.1C. References: [1] Anqiang Pan, et.al, ACS Appl. Mater. Interfaces, 4, 3874-3879 (2012) [2] An Qiang Pan, et.al, Energy Environ. Sci. 6, 1476-1479 (2013)

Resume : Among the various energy storage systems, the room temperature sodium sulfur (RT-NaS) battery has attracted considerable attention as a large-scale energy storage system due to its abundance of source and low cost and high energy density. However, most of RT-NaS battery has the critical challenge, such as the high irreversible capacity, low coulombic efficiency, and fast capacity decay. It is due to intermediate product, long chain polysulfides (NaSx, 4 < x ≤ 8) formed during sodiation/disodiation, which is easily dissolved into the organic electrolyte. The polysulfides move between the electrode through a polymer membrane and undergo unwanted redox reactions (known as the shuttle effect). In this presentation, we will introduce a new electrochemical method to suppress the shuttle effect in RT-Nas and hence improve its performance, that is artificially forming a protective solid electrolyte interphase (SEI) on the sulfur cathode using in situ electrochemical method with various electrolyte additives containing phosphorous, fluorine, selenium, etc.

Resume : The utilization of lithium metal anodes for lithium secondary batteries faces huge challenges since the uncontrollable lithium dendrite growth and large volume change during Li plating/stripping. The lithium dendrite growth generates non-uniform electric fields that increase resistance and short-circuits that cause safety problems. Here in, the lithium dendrite growth was observed according to the types of separator such as PE, glass fiber, and cellulose by SEM. Depending on the interface among electrolyte, separator and lithium metal, the lithium dendrite growth showed different morphology. Consequently, the life time and resistance changes were measured by using lithium plating/stripping experiment. Moreover, the interface was covered with the same material (PVDF-HFP nanofibers web) to remove the effects of the interface materials and the lithium plating/stripping characteristics were analyzed. In order to analysis for these studies, SEM, FT-IR, and XRD were used for morphology observation, SEI and compound analysis, respectively. The lithium plating/stripping experiment was carried under 2 mA/cm2 and 2 mAh/cm2 and the life time of the lithium metal anode was increased more than 500 hours.

Resume : Nowadays, transition metal oxides have been extensively studied to replace graphite anodes in Li-ion batteries. Among them, ZnO is a low cost material and has the advantage of excellent theoretical capacity and chemical stability. However, ZnO is one of representative materials having a critical drawback of the mechanical pulverization as an anode, which leads to degradation of electrochemical performance due to large volume expansion. In this study, we developed ZnO nanorods (NRs) decorated with Ni nanoparticles using the electrochemical method and subsequent galvanic reaction. Ni nanoparticles increase the electrical conductivity of ZnO NRs and facilitated a faster kinetics process due to the catalytic effect of Ni. We also propose an effective way to create huge free-volume by filling ZnO NRs with the spherical PVDF. This structure as an anode has high electrochemical capacity and cyclability because the free-volume accommodates the strain induced by the intercalation/de-intercalation of Li ions.

Resume : The redox chemistry of organic molecules is increasingly attracting interest as it has the potential to provide battery electrode material candidates combining high capacities, practical redox potentials and allow for transition metal-free battery chemistries. While quinone-based compounds have been extensively explored, achieving high redox potentials has long remained a challenge. Recent efforts, involving electron-withdrawing substitution groups or cation substitution in the quinone salt, allowed to reach potentials above 3V vs Li+/Li. In an effort to pursue this investigation of high potential quinones, we directed our interest towards the molecular modification of carboxylated quinones. A new, air stable tetralithium salt will be discussed here. Structural and chemical stability was evidenced through PXRD and FTIR analyses respectively, and afterwards confirmed through galvanostatic cycling with an observed discharge potential of 3.2V vs Li+/Li. Furthermore, crystallographic data allowed for the resolution of the crystal structure of the salt. Investigation of the solubility highlighted the inadequacy of traditional battery electrolytes (carbonates, glymes), whereas less conventional ionic liquids displayed satisfying insolubility of the lithium salt.

Resume : In the current chemical battery system, lithium batteries are considered as the most promising energy storage devices due to their high energy density, long cycle life, and no memory effect. The conventional lithium ion batteries use an organic liquid electrolyte. Although the liquid electrolyte has high ionic conductivity and good interfacial contact, it's not safe, it has a low lithium ion migration number, and it's easy to leak. Volatility, flammability, and poor safety are the main disadvantages of liquid electrolyte, and these drawbacks hinder the further development of lithium batteries. Compared with the liquid electrolyte and the inorganic solid electrolyte, the solid polymer electrolyte (SPE) has the advantages of good safety performance, flexibility, easy processing into a film, and it also can suppress the problem of lithium dendrites. Phosphorus-containing polymers have many interesting properties, such as flame retardation, corrosion inhibition, bonding to metals, etc. In this work, a series of phosphorus-containing polymers are explored to prepare SPEs. Poly(dimethyl(methacryloyloxy)methyl phosphonate) (PMAPC1) was synthesized by the reversible addition-fragmentation transfer (RAFT) process with a good control over the molar mass. Poly(oligo(ethylene glycol) methacrylate-co-dimethyl-(methacryoyloxy) methyl phosphonate) or poly(OEGMA-co-MAPC1) was synthesized by free radical polymerization of dimethyl(methacryloyloxy)methyl phosphonate) (MAPC1) and oligo(ethylene glycol) methacrylate (OEGMA). SPEs were prepared by loading the homopolymer PMAPC1 or copolymer POEGMA-co-MAPC1 with various LiClO4 or LiTFSi amounts. The ionic conductivity of the SPE prepared from homopolymer PMAPC1 is above 10-3 S/cm at 80 °C, and it can be used for batteries operating at high temperature, because the stability of PMAPC1 is more than 200°C. The SPE prepared from copolymer PEGMA-co-MAPC1 can reach ionic conductivity values as high as 1x10-4 S/cm at room temperature. Finally, the electrochemical stability window of phosphorus-containing polymers is broad. So phosphorus-based polymers can be seen as promising candidates for SPEs.

Resume : In order to realize sustainable renewable energy supply, large-scale energy storage system is needed to overcome the problem of intermittency of power generation. Vanadium redox flow battery (VRFB) presents the most viable solution but faces the problem of high material cost. In this study, we have established a cost-effective process to prepare vanadium electrolyte for VRFB from an untouched industrial waste, ammonia slag, by pH control under atmospheric condition (< 95°C). The extracted solution changed color during electrolytic reduction as yellow, blue, dark green and purple, matched with the color of V5+, V4+, V3+, and V2+, respectively, indicating an accurate change of the valences without forming precipitates. Electrolyte prepared from the recycled vanadium showed almost the same charging/discharging performances like the one prepared from commercial V2O5 reagent in battery tests at the first several cycles, but degraded rapidly after 16 cycles, which should be affected by the existence of impurities on the negative electrode to limit the reduction of V3+ to V2+. The miniature VRFB prototype built by employing 3D printing technique showed much higher performance than the H-cell, indicating the flow cell configuration could help to push up the diffusion limit of vanadium redox by flowing the electrolyte solution through the electrodes, as well as reducing IR loss and water splitting to increase the efficiency.

Resume : Supercapacitors (SCs) are considered as a promising clean energy storage device. However, to meet the continuously rising energy demand for portable power, it is crucial to enhance the energy density of present SCs, without sacrificing their power and high life-cycle. Toward this goal, integration of pseudocapacitive materials (such as iron oxides, FeOx) has been pursued. High-performance FeOx-based electrodes are mostly prepared by employing hydrothermal, chemical vapor, atomic layer or electro-deposition methods, which require current collectors other than the commercial Al thin foils. Therefore, a significant amount of inactive mass is added to the device and the fabrication is incompatible with the currently used roll-to-roll paste-deposition processes. Importantly, they operate in low-voltage aqueous electrolytes, limiting their energy. Here, we report FeOx-based SC electrodes with high affinity for organic electrolytes owing to hybridization with a covalently functionalized graphene derivative (cyanographene, G-CN) used as compatibilizer and charge carrier support for the FeOx nanoparticles. After a cost-effective and up-scalable 15 min microwave-assisted synthesis, the hybrid was casted as paste on Al foil for the assembly of symmetric SCs. Therefore, exploiting the properties of G-CN to purposefully modify the features of FeOx, a combined high energy and power density was achieved (with respect to total mass of the electrodes, i.e. including current collectors), surpassing previous FeOx-based SCs.

Resume : Our society is asking for more efficient energy supplies. Amongst the available technologies, lithium-ion batteries (LIBs) are to date the most suitable for electric vehicles (EVs), power tools and portable electronics. Despite, the power performances are still unsatisfactory given the sluggish kinetics of positive and negative electrodes. Few of the available electrochemical storage technologies can simultaneously deliver both, high energy and high power. The intra-electrode hybridization of LIB and electrochemical double-layer capacitors materials has been proposed as one alternative and mixed performances were attained. However, there is little synergy between constituents in standard EDLCs - LIBs hybrid formulations resulting in the simple superposition of the characteristic features of both components. The power and energy responses are decoupled - at high-current densities, the response is dominated mainly by the EDLC component, the LIB component ultimately penalizing the energy density of the hybrid device. Here, we present the performances of hybrid electrodes comprising of a common interrelation material (LMO - NMC) and a redox polymer materials bearing nitroxide radical playing the role of power buffer. Thanks to the synergistic effect between both component, improvement of the power performances as well as the extension of the cycle life can be attained without penalizing the energy density of the hybrid electrode. We also present the work done for the implementation of this concept in the automotive sector.

Resume : Lithium sulfur (Li-S) cells are promising candidates for high-energy-density battery systems. However, employing conventional liquid electrolytes leads to continuous degradation in Li-S batteries because of soluble reaction intermediates.[1] Today, ongoing developments in the field of solid electrolytes are drawing attention to all-solid-state Li-S cells in which the so called polysulfide shuttle is physically prevented by a solid separator.[2] Although modern thiophosphate electrolytes provide sufficient ion conductivities, their low electrochemical stability is still a major bottleneck for application. Despite theoretical calculations suggesting narrow thermodynamic stability windows,[3] stabilities up to 5 V vs. Li/Li+ are often claimed from cyclic voltammetry using metallic electrodes. Contradictorily, redox activity at lower potentials was reported for thiophosphate electrolytes.[4,5] In this presentation, we will report how employing a high surface area carbon-electrolyte composite working electrode helps visualize the practical stability window of state-of-the-art solid electrolytes. Thereby, an insight into the underlying chemistry, i.e. the oxidation of thiophosphate building units, is given. Based on these findings, cycling conditions can be tailored to increase capacity retention and cycling stability. Furthermore, we show the reversible cyclability of the oxidized species act as pseudo active material adding additional cell capacity while leading to a degradation of the long-term performance. By restricting the cycling window, the overall cell performance can be increased significantly. References: [1] Wild, M.; O’Neill, L.; Zhang, T.; Purkayastha, R.; Minton, G.; Marinescu, M.; Offer, G. J. Lithium Sulfur Batteries, a Mechanistic Review. Energy Environ. Sci. 2015, 8 (12), 3477–3494. [2] Janek, J.; Zeier, W. G. A Solid Future for Battery Development. Nat. Energy 2016, 1 (9). [3] Zhu, Y.; He, X.; Mo, Y. Origin of Outstanding Stability in the Lithium Solid Electrolyte Materials: Insights from Thermodynamic Analyses Based on First-Principles Calculations. ACS Appl. Mater. Interfaces 2015, 7 (42), 23685–23693. [4] Koerver, R.; Walther, F.; Aygün, I.; Sann, J.; Dietrich, C.; Zeier, W.; Janek, J. Redox-Active Cathode Interphases in Solid-State Batteries. J. Mater. Chem. A 2017, 22750–22760. [5] Han, F.; Gao, T.; Zhu, Y.; Gaskell, K. J.; Wang, C. A Battery Made from a Single Material. Adv. Mater. 2015, 27 (23), 3473–3483.

Resume : In this work, we successfully fabricated 3D network vanadium oxide (VOx) and manganese oxide (MnOx) nanofibers on the conductive paper (PVA-acetamide-LiClO4-graphite/paper, PGP) as electrodes linked with eco-friendly PVA-acetamide-LiClO4 (PAL) deep eutectic solvent-based gel electrolyte for high-voltage wearable asymmetric supercapacitors (HVWASCs). Eco-friendly PAL gel electrolyte with self-supporting electroactive species have been generally accepted in this work as a unique type of cost-effective and green electrolyte that possibly involve bulky concentration of the electroactive species and great working potential window, accordingly high performances. HVWASCs are able to work with a great operating voltage of 4.2 V, and supply outstanding energy/power density (245 Wh/kg at 0.18 W/kg and 95.3 kW/kg at 98 Wh/kg). The HVWASCs demonstrate remarkable cycling stability and durability after 6000 cycles, including bending and twisting (capacitance retention of 91.5%). The HVWASCs demonstrate great potential as the prospective candidate for wearable/flexible electronic devices and Internet of Things (IoT) applications.

Resume : To meet the demand for smaller electronic devices, interconnect technologies have advanced as one of high integration technologies. Microvia or Through-Silicon Via (TSV), a vertical interconnect between chips for the shortest path, is one of the interconnect technologies, which offers several benefits such as low power consumption and high signal transmission. However, it is difficult to achieve a reliable microvia or TSV, in particular, with a defect-free filling. Levelers are one of the organic additives for electrodeposition and believed to play a crucial role toward the defect-free filling. Nevertheless, the study about structure-property relationships of the levelers has not been done much. In our previous report, a triethylene glycol (TEG)-based leveler was synthesized, and it showed the defect-free filling performance on TSV.1 Inspired by the results, we tried to synthesize the levelers with modified structures. In this report, the structures of the synthesized levelers and their electrochemical properties will be presented. Although all of the synthesized levelers showed convection-dependent adsorption characteristics, which is the distinctive property of the levelers, the different electrochemical properties were shown depending on the structure of levelers. The gap-filling results with the synthesized levelers will be also reported.

Resume : Lithium secondary batteries have been widely implemented as energy storage devices such as mobile electronics, electric vehicles, and energy storage system. Conventionally, the lithium secondary battery with a liquid electrolyte has known to have several disadvantages including the fact that the safety is weakened and the operating temperature is limited due to the presence of an organic electrolyte. To overcome these weaknesses, the solid electrolyte such as a lithium-ion conductor has gained a considerable attention [1]. However, lithium secondary batteries composed of solid electrolyte are still immature to replace conventional liquid electrolyte due to their low current density and limited output power. An example of the drawbacks is the interfacial resistance between the solid electrolyte and the electrode, which is relatively higher than that of the liquid electrolyte system. The addition of an adequate amount of the solid electrolyte in the composite negative or positive electrode may be a solution to reduce the interfacial resistance. In this study, we used different contents of LSTP-based solid electrolyte in preparing graphite composite anode and compared their electrochemical performance to prove the evolution of the interfacial resistance between the solid electrolyte and graphite composite anode. The interfacial resistance is also further analyzed by the surface concentration pattern of Li ions, which can be analyzed using electrochemical strain microscopy (ESM) [2]. The ESM technique will be presented more precisely in relation with Li conduction pathway in the interfaces between the LSTP solid electrolyte and the graphite anode. References: [1] Y. Kato, S. Hori, T. Saito, K. Suzuki, M. Hirayama, A. Mitsui, M. Yonemura, H. Iba, R. Kanno, Nature Energy 1 (2016) 16030. [2] E. Strelcov, S.M. Yang, S. Jesse, N. Balke, R.K. Vasudevan, S.V. Kalinin, Nanoscale 8 (2016) 13838-13858.

Resume : The sol-gel process was successfully prepared for synthesizing amorphous Li-La-Zr-O (a-LLZO) electrolyte. With unlimited compositions of the amorphous structure, the combinatorial approaches were systematically developed to seek for optimal composition and optimized experimental condition (400˚C annealing temperature). The amorphous structures with predicted high atomic disorder were displayed by GI-XRD analysis. The electrochemical results performed that the ionic conductivity considerably improved with increasing of Li content, specifically from 4.8 x 10-8 S.cm-1 (Li8La2Zr2O) to 1.18 x 10-6 S.cm-1 (Li18La2Zr2O) and the stoichiometric ratio 18:2:2 also resulted in the lowest activation energy (Ea). Exceptionally, the LLZO-coated LiCoO2 (LCO) coin cell showed a greater cycling performance compared to bare-LCO coin cell at the optimum ratio of LLZO. We highly believe that LLZO is a promising material for solid electrolyte battery.

Resume : All-solid-state batteries (ASSBs) considered as the next generation energy storage for electric vehicle application due to their outstanding stability and energy density. Despite these advantages, the interfacial instability among solid components including active material, solid electrolyte, and conducting agent has been noted as a main cause of degradation of the cell performance. Especially, there have been recent reports that the carbon conducting agents accelerate the decomposition of solid electrolytes (SEs) and lead to poor cycle life of the ASSBs, but the underlying mechanism on the carbon-induced decomposition and any solutions were not proposed yet. Therefore, developing suitable conducting agents is one of the urgent options to improve the performance of the ASSBs. In this work, through various analytical techniques, for the first time, we found that the decomposition of sulfide electrolyte was closely associated with the surface functional groups on the carbon additive, apart from the electrochemical SE decomposition previously reported. Moreover, we introduced a novel graphitic hollow carbon (GHC) as a solution to improve interfacial stability among the cathode components. The GHC was synthesized by simple heat treatment, and shows few surface functional groups and enhanced electrical conductivity. The LiNi0.6Co0.2Mn0.2O2 cell containing GHC exhibited better initial coulombic efficiency, discharge capacity, and cycling performance than the cell incorporating with general conducting agents such as super P, Ketjen black, and carbon nanotubes under the condition that the external pressure effects were intentionally excluded. In addition, the GHC could also fulfill similar functions toward improving the cell performance of the LiCoO2 based cells, confirming the GHC can be universally applicable to many other cathode materials. The current approach reveals the importance of the careful selection of conducting agent in warranting stable interfaces at composite cathode and thus improving the cell performances of the ASSBs.

Resume : Key Words: CaNi5 based alloys; mechanical alloying; structural and morphological techniques; Ni-MH batteries; electrochemical techniques. Abstract The CaNi5-xMnx (or x=0.2, 0.3, 0.5 and 1) powder was synthesized by mechanical alloying (MA), under an atmosphere of argon at room temperature, at different milling times (2, 10, 20, 30, 40, 50 and 60h) with ball to powder weight ratio of 8: 1 and 12:1. The structural and morphological characterizations of the CaNi5-xMnx (or x=0.2, 0.3, 0.5 and 1) powder were carried, respectively, by scanning electron microscopy (SEM) and X-ray diffraction (XRD). After 2h, all the alloys had a biphasic structure, two major phases, (Ni, CaNi3) and (Ni, Ca2Ni7), remained virtually unchanged when a small amount of Mn was added independently of powder weight ratio. After more than 40 hours of milling, the same peaks of the Ni, CaNi3 and Ca2Ni7 phases are appeared, while the intensity of the peaks are decreased, indicating an additional amorphising process. After 50 hours of milling, this damping was followed by the crystallization amorphising. The electrochemical properties of CaNi5-xMnx (or x=0.2, 0.3, 0.5 and 1) electrodes were studied at different milling times (10, 20, 30, 40, 50 and 60h) and in KOH electrolyte concentrations (6M) at ambient temperature, as anodes in the Ni-MH battery. Different techniques were used, such as galvanostatic polarization, potentiostatic polarization and potentiodynamic polarization.

Resume : Lithium has been commercially applied in secondary batteries for several decades now and large effort is put into understanding and improving electrode materials, electrolytes, separators, and basically all other parts that make up a typical cell. The anode current collector, however, has seen no changes and copper is universally accepted as the go-to material. Besides its high conductivity, the main argument for the use of copper as current collector is that it does not form intermetallic compounds with lithium in the concerned temperature range. While this is true, it does not exclude diffusion of lithium into copper and formation of a solid solution or lithium segregation in grain boundaries. Diffusion is a seemingly fundamental aspect of the interaction between two so commonly used materials, but literature does not offer conclusive insight into the topic. While copper is often labeled as “inert” vs. lithium, it is also used as coating material on anodes, where it is supposed to allow lithium transfer. Claims about high diffusivity of lithium in copper and resulting capacity loss in the current collector have been made in the past. We want to shine some light on the actual interaction between lithium and copper by giving reliable values for the lithium diffusion coefficient in copper single crystals. Furthermore, we were able to observe the effect of grain boundaries on diffusion and lithium segregation.

Resume : Design and fabrication of environmentally friendly, portable and wearable electronics employing a flexible substrate that synchronously harvests and stores energy by the coordination of energy harvesting and storage mechanisms are extremely essential. In this research work, we highlight the design and fabrication of a natural bio-piezoelectric driven flexible self-charging asymmetric supercapacitor (SCASC) comprised of nickel-cobalt hydroxide nanoplies decorated copper oxide nanoflakes grown on flexible copper foil (NiCoOH-CuO@Cu foil) as a binder-free positive and room temperature reduced graphene oxide coated copper foil (RGO@Cu foil) as negative electrodes with a PVA–KOH gel electrolyte soaked fish swim bladder as bio-piezoelectric separator (BPES). The self-charging features of the SCASC were demonstrated by mechanically deforming it under human finger tapping and by casual natural body motions. Our rectification-free SCASC device can be charged up to 281.3 mV from its initial open circuit voltage (130 mV) within ~ 80 s under continuous finger tapping at f ≈ 1.65 Hz. Furthermore, eight series-connected SCASC can instantly light-up four red light-emitting diodes and power-up numerous portable electronic gadgets on frequent tapping/deformation. Hence, our light-weight flexible SCASC device with exclusive design resembles its desirability for future generation smart and wearable electronics.

Resume : Li-ion batteries are often the key components in several applications like: portable electronic devices, electric vehicles (EVs) or hybrid electric vehicles (HEVs) which are strongly dependent on an efficient electrochemical storage system. It is mostly imperative to set higher standards in order to improve the overall Li-ion battery performance, which can lead to increased safety characteristics, long cycle life, low cost production and either high energy density or high power density. These key factors, are highly correlated with each major component placed inside a battery, (eg: electrodes, separator, electrolyte) in addition to the operating conditions. Using TiO2 based materials turns out to be the most viable option for replacing conventional graphite-based anodes, which suffers from potential safety issues. The overall performance of TiO2 based anodes can be further enchanced in practical applications if the electrode material is used as a nanoscale structure. Furthermore, a wide range of TiO2 nanostructures (nanoparticles, nanowires, nanotubes, nanorods etc.) in pristine form or as composites, and their possible use for LIBs have been intensely studied in recent years. In contrast with commercial graphite anodes, these TiO2 nanostructures exhibit elevated operating potential (0,8 V vs. Li/ Li+), a decent theoretical capacity (330 mAh/g) and good safety. Nonetheless, TiO2 based materials are eco-friendly due to their low toxicity, they are abundant and relatively low in price. In this paper we described an effective approach to optimize titanium dioxide nanowires on titanium substrate-based anodes with the combined use of two techniques, namely spin coating and electrospinning. Ultimately, the practical challenges and future perspectives for nanostructured TiO2 based materials towards LIB technology and energy storage devices are outlined.

Resume : Ab initio modelling can be highly useful to determine accurate, fundamental properties of battery electrodes, providing a suitable method is used. Density Functional Theory (DFT), commonly used in such atomistic modelling, is impacted by a 'self-interaction error', which ensures regular DFT functionals such as PBE are highly inaccurate in their description of transition metals. Historically, this error has been corrected through addition of U parameters – however, these require careful tuning to replicate experimental results, need to be varied during modelling of deintercalation, and are highly sensitive to changes in composition or alloying, making them unideal for the description of complex cathodes, such as the NMC family. Hybrid DFT, combining Hartree-Fock exchange with DFT, offers a standardised, minimally parameterised method in the HSE06 functional – however, some previous studies have highlighted the disagreement of HSE06 with the band gap of LiCoO2 recorded from XPS (avoiding the d-d transitions that obscure optical spectra), suggesting that scaling of the Hartree-Fock component is necessary, and thus HSE06 is no more transferable than DFT+U as a method. In this study, we address this problem, demonstrating through a combination of HSE06 and high-level quasiparticle self-consistent GW calculations that the perceived value of the LiCoO2 band gap is underestimated, and that HSE06 represents a cost-effective, accurate and transferable method to describe the structural, electronic and electrochemical properties of LiMO2 cathode materials (M= Mn, Co, Ni).

Resume : Li-ion batteries (LIB) have governed a large part in the rechargeable energy storage market, like portable electronic devices and electric vehicles. However, in recent 20 years, research in sodium ion batteries (NIB) has been resurrected, driven by its adequate intercalation property and cost-effectiveness and nowadays, NIB has already become a promising candidate for large-scale grid storage application. In 2015, we reported that anionic redox, with the advantage of breaking the limit of theoretical capacity based on cationic redox, can be activated in Na-based layered materials in a similar way as in Li-rich compounds1. Unlike in LIB, there are only a few reports on research in anionic redox in sodium-based compounds, despite that it is a promising way to counteract the downside of relatively low energy density of NIB and expand the applicable domain for NIB. While anionic redox activity is proposed to explain extra capacity observed in some Na based layered oxides, only a few deep investigations of parameters governing the activation and reversibility of anionic redox are reported. Recently, P. Bruce et al. showed that doping P2-type layered oxides with Mg alkaline-earth2 instead of alkaline element (A=Li or Na)3allows activating the anionic redox showing that the A-O-A bond is not the main parameter governing anionic redox activity. To go deeper in the understanding of parameters governing the activation, reversibility and efficiency of anionic redox, here we present the investigation of P2- Na2/9Mn7/9Zn2/9O24 a model compound selected to focus only on oxygen redox and using as doping element Zn, much more electronegative than previously reported Mg or Na, Li. Combination of electrochemical techniques carried out on both half and full cells, operando XRD and ex-situ HAADF-STEM techniques are used to evidence the presence of extra capacity and the mechanism occurring upon cycles, while the participation of oxygen redox chemistry in charge compensation is proven using hard X-ray photoelectron spectroscopy (HAXPES) and operando X-ray absorption spectroscopy (XAS). Opposite to what has been speculated for Mg doped compound, the observed migration of Zn during cycling without O2 release indicates that the stability of the doping element does not necessarily trigger the stability of the peroxo-like species. Density functional theory (DFT) calculations confirms the presence of an oxygen nonbonding state that triggers the anionic redox activity in this material, which explains the feasibility of using an even more electronegative Zn than Mg in tuning iono-covalency of Mn-O for anionic redox activation. This work steps further in the design of materials with anionic redox behaviour and understanding the charge compensation mechanism, which offers more possibilities to the exploration of anionic redox activity in layered oxide. Reference: 1. Rozier, P. et al. Anionic redox chemistry in Na-rich Na2Ru1 − ySnyO3 positive electrode material for Na-ion batteries. Electrochem. commun. 53, 29–32 (2015). 2. Maitra, U. et al. Oxygen redox chemistry without excess alkali-metal ions in Na 2/3 [Mg 0.28 Mn 0.72 ]O 2. Nat. Chem. 10, 288–295 (2018). 3. Rong, X. et al. Anionic Redox Reaction-Induced High-Capacity and Low-Strain Cathode with Suppressed Phase Transition. Joule (2018). 4. Bai, X. et al. Anionic Redox Activity in a Newly Zn-Doped Sodium Layered Oxide P2-Na2/3Mn1− yZnyO2 (0 < y < 0.23). Adv. Energy Mater. 8, 1802379 (2018).

Resume : One of the most promising strategies to increase the positive electrode energy density is by increasing the voltage and useable atomic fraction of lithium in intercalation materials. These materials are designed to undergo reversible delithiation with a concomitant oxidation of the otherwise mostly rigid host lattice and the generation of vacancies at the former lithium sites. Oxygen redox, wherein electrons are reversibly removed from lattice oxygen during delithiation, has been recently shown to be able to support deep delithiation from oxide intercalation materials with a high average voltage, making it extremely attractive for developing high energy density electrodes. However, oxygen redox almost invariably results in irreversible voltage fading with cycling as well as charge-discharge voltage hysteresis. The origin of these unfavourable electrochemical properties has remained mostly a mystery due to the lack of understanding of the nature of the oxidised oxygen species and the materials properties governing their stability and the reversibility of their formation. In this talk, by revealing the mechanism of oxygen redox, we establish the origin of its associated unfavourable electrochemical properties. I show that when oxygen is oxidised, it experiences a strong driving force to change its local bonding configuration in order to stabilise its higher oxidation state. Bonding changes that can stabilise oxidised oxygen include increasing the bond order with a neighboring transition metal through a substantial contraction of their existing bond, or forming a new bond with another oxygen to form a short O–O dimer. Crucially, these bonding changes cannot typically be accommodated by minor distortions to the host crystal structure, and so structural defects form within which the desired bonding changes can take place. It is the generation of these structural defects – most commonly observed as migration of transition metals into vacant lithium sites during delithiation – that gives rise to the disordering of the host lattice that is at the root of the poor electrochemical properties of oxygen redox.

Resume : We report on the synthesis of a library of perovskite oxides with the composition La1-xSrxBO3-δ (x = 0-1; B = Fe, Mn, Co) to systematically study anion-based pseudocapacitance. The electrochemical capacitance of these materials was evaluated by cyclic voltammetry and galvanostatic charging/discharging in 1 M KOH with the highest specific capacitance of 492 F g-1 at 5 mV s-1 for La0.2Sr0.8MnO2.7. We find that greater oxygen vacancy content (δ)-caused by systematic incorporation of Sr2+-linearly increases the surface-normalized pseudocapacitance for the three B-site transition metal series investigated, but the slope of the trends is controlled by the B-site element. Furthermore, the first all-perovskite asymmetric pseudocapacitor has been successfully constructed and characterized in neutral to alkaline aqueous electrolytes with a maximum voltage window of 2.0 V in 1 M KOH . An asymmetric, perovskite pseudocapacitor’s cell voltage can be increased by increasing the voltage difference between the perovskites’ different transition metal redox potentials in the B-site.. Asymmetric capacitors constructed from across the series cannot be accounted for by oxygen vacancies alone. SrCoO2.7, La0.2Sr0.8MnO2.7, and BM-Sr2Fe2O5 were made with the BM-Sr2Fe2O5//SrCoO2.7 combination performing the best with asymmetric capacitors possessesa high both higher energy density of (31 Wh kg-1 at 450 W kg-1) and power density of (10,000 W /kg-1 at 28 Wh /kg-1).

Resume : State of the art cathode materials for Li-ion batteries such as LiNi1/3Mn1/3Co1/3O2 rely on redox activity of transition metal cations to provide charge capacity. Recently, the possibility of using the oxide anion as a redox center in Li-rich rock salt oxides was established as a new paradigm in the design of cathode materials with enhanced capacities (> 200 mAh/g). To increase the lithium content and access electrons from oxygen-derived states, these materials typically require transition metals in high oxidation states, which can be achieved easily using d0 cations. However, Li-rich rocksalt oxides with high valent d0 cations such as Nb5+ and Mo6+ show strikingly high voltage hysteresis between charge and discharge, the origin of which is not yet understood. In this work, we study the electrochemical properties of Li4.15Ni0.85WO6 and its charge compensation mechanism by XAS, XPS and Raman spectroscopies. It shows a large reversible capacity of 200 mAh/g, without accessing the Ni3+/4+ redox couple, implying that over 2/3 of the capacity is due to anionic redox. The presence of the 5d0 W6+ cation affords extensive (> 2 V) voltage hysteresis associated with anionic redox. We present experimental evidence for the formation of strongly stabilized localized O-O single bonds that explain the energy penalty required to reduce the material upon discharge. The extent of hole localisation appears as the key design target to combine reversible capacity and high energy efficiency.

Resume : Commercial LiNi1/3Mn1/3Co1/3O2 material is treated in appropriate way to provide cathode material with reasonable charge capacity and high cycling stability upon different charging/discharging rates. Electrochemical performance of the tested materials is studied by cyclic voltammetry of Li insertion and galvanostatic chronopotentiometry. An influence of calcination, surface area and particle size uniformity on the charge capacity and cycling stability is evaluated and the parameters of the optimized samples providing charge capacity of 141 mAh/g (cyclic voltammetry) and 144 and 135 mAh/g (galvanostatic chronopotentiometry) at 1 and 10C, respectively, represent a platform for scale up during the next period of the research. Acknowledgments: This work was supported by the Ministry of Industry and Trade of the Czech Republic (contract TRIO FV20471).

Resume : Li-rich NMC cathodes are the frontier generation of the positive electrodes in the Li-ion batteries, which have achieved capacities of 300 mAhg-1. Despite their high capacity, they suffer from sever structural degradation that results in rapid capacity and voltage decay during repeated electrochemical cycling. The research on the origins of such rapid degradation have been troublesome due to the structural complexity of these materials. In fact, there is still an ongoing debate on the atomic structure of these cathodes in the scientific community and their structure have been denoted in three ways; (1) a solid solution with the original (R3 ̅m) layered structure, where some of the extra Li ions are occupying the transition metal sites (2) a nano-composite of the C2/m Li2MnO3 and the R3 ̅m LiMO2 with the general formula of xLi2MnO3-(1-x)LiMO2 (3) a single phase solid solution C2/m Li¬2MnO3 phase with random Li/TM mixture. In our research we have utilized aberration corrected scanning transmission electron microscopy (AC-STE) and electron energy loss spectroscopy (EELS) to elucidate the atomic configuration of such cathode nanoparticles. Our comprehensive results reveals that the nano-composite xLi2MnO3-(1-x)LiMO2 notion is the correct atomic arrangement of Li-rich cathodes. Furthermore, we have discovered that there are strained phase boundaries with deviation in local chemical composition that can be attributed as an origin for rapid degradation of such cathode materials.

Resume : As a derivative of LiNiO2, NCA (LiNi1-x-yCoxAlyO2) is widely used in the electric vehicle industry because of its high energy density. It is thought that Co and Al both play important roles in enhancing NCA material properties. However, there is no solid evidence in the literature that clearly shows that Co is required in NCA with high nickel (e.g. when 1-x-y > 0.9) content. Therefore, a systematic study on the roles of different cation substituents in a series of LiNi1-nMnO2 (M = Al, Mn, Mg, or Co) materials was made. In-situ X-ray diffraction (XRD) and differential capacity versus voltage (dQ/dV vs. V) studies showed that the multiple phase transitions in LixNiO2 during charge and discharge, thought to cause poor charge-discharge capacity retention, were suppressed in LixNi0.95M0.05O2 (M = Al, Mn, or Mg), while 5% Co failed to suppress the phase transitions. First principles calculations were made to understand the function of each substituent. Accelerating rate calorimetry shows that unlike Al, Mn, or Mg, Co has no contribution to safety improvement. Therefore, we believe that Co brings little or no value at all to NCA-type materials with high Ni content (> 90% Ni in the transition metal layer) and we hope this presentation will spur more interest in Co-free materials.

Resume : Layered Li-rich/Mn-rich NMC is characterized by a high initial capacity of more than 250 mAh/h and a lower cost and higher thermal stability than LiCoO2.1 However, its commercialisation is currently still hampered by significant voltage fade, most certainly related to irreversible transition metal migration upon electrochemical cycling.2 For example the reduction of Mn4+ to Mn3+ and subsequent migration causes a transition from a layered to a spinel structure, having a devastating effect on the electrochemical properties. Substitution of Mn4+ by isovalent, redox inactive cations which are supposed to be not prone to migration upon charging, is believed to be a valuable strategy to stabilize the layered structure upon charging.3 Here, we probe the partial substitution of Sn4+ for Mn4+ in Li-rich/Mn-rich NMC. Via an extended series of characterization techniques, including XRD, STEM-EDX, HAADF-STEM and ABF-STEM, the structural properties, including substitution limit, layeredness and cation ordering, of Sn substituted Li1.2Ni0.13Co0.13Mn0.54-xSnxO2 are investigated and correlated with both synthesis method and electrochemical performance. References 1. Koga, H. et al. J. Phys. Chem. C 116, 13497–13506 (2012). 2. Wei, Z. et al. J. Power Sources 281, 7–10 (2015). 3. Deng, Z. Q. et al. Phys. Chem. C 115, 7097–7103 (2011). Acknowledgements The authors acknowledge Research Foundation Flanders (FWO) project number G040116N for funding.

Resume : The use of operando diffraction has taken a major step forward, in no small part due to the increase in flux at large scale facilities such as synchrotrons and neutron spallation sources. While the X-rays are absorbed by the battery casing which necessitates special cells with windows, neutrons have a penetration depth large enough to probe the entirety of cell. This has allowed measurements directly on commercial batteries, giving unique insights into the evolution of cell parameters and composition of the cathode and anode phase, but also showing Li-consumption by decomposition of the electrolyte and plating of lithium metal. When measuring on commercial cells, contributions from all parts of the cell are observed which complicates the analysis of the diffraction data. A desire also exists to measure on non-commercial electrode materials prepared in the lab. Thus, there exists an incentive to develop a measuring cell which allows easy measurement on a variety of different cathode materials, either commercial or synthesized. In this work, we present a new operando neutron diffraction battery cell, especially designed for the new beamline ErwiN at the FRM-2 research reactor outside of Munich, Germany. The cell uses a Zr/Ti-alloy with negligible scattering strength to eliminate contributions from the casing. We present data on the commercial cathode materials LiFePO4 and LiNi1/3Mn1/3Co1/3O2 to demonstrate the capabilities of the cell, as well as on the non-commercial cathode material Li3V2(PO4)3. Li3V2(PO4)3 is interesting, as it has the highest gravimetric capacity among the known phosphates (197 mAh g-1). The material displays a complex series of phase transformations during charge and discharge, and interestingly, these transformations are very dependent on the number of Li-ions extracted during charging. The material has been investigated using operando synchrotron X-ray diffraction[1], but operando neutron diffraction is important to uncover the exact nature of the Li-ion dynamics. [1] D.R. Sørensen, J.K. Mathiesen, D.B. Ravnsbæk, Dynamic charge-discharge phase transitions in Li 3 V 2 (PO 4 ) 3 cathodes, J. Power Sources. 396 (2018) 437–443. doi:10.1016/j.jpowsour.2018.06.023.

Resume : The spectroscopic region characterized by interband transitions, and plasmon excitations is rarely used in spectroscopy of Li ion battery materials. One reason being the large number of different excitations observed in this region as well as the difficulty in interpreting their nature and origin. We have determined the spectral features observed in the valence energy loss (VEELS) spectra of Lithium-Manganese-Nickel spinel oxides (Li-Mn-Ni-O) with respect to Mn valency changes after insertion/extraction of lithium ion [1]. Li-Mn-Ni-O spinel oxides are of interest primarily due to their applications as cathode materials in Li-ion batteries [2]. In Li-ion batteries, phase stability, voltage limits, and safety are closely related to the character of the transition metal ion in the cathode materials. This includes valency, spin state, co-ordination, and covalency [3]. We have determined the nature and origin of the spectral features observed in the valence spectra with respect to Mn valency changes during the lithiation of LiNi0.5Mn1.5O4 to Lithium rich Li2Ni0.5Mn1.5O4. The lithiation process is characterized by a Mn valency change from Mn 4 in LiNi0.5Mn1.5O4 to Mn 3 in Lithium rich Li2Ni0.5Mn1.5O4. The VEELS spectra of LiNi0.5Mn1.5O4 is characterized by sharp peaks around 7-10 eV whose intensity decrease with lithiation to Li2Ni0.5Mn1.5O4.Using band-structure calculations and molecular orbital considerations we show that the intense peaks in the VEELS spectra of LiNi0.5Mn1.5O4 have a large contribution from ligand-metal-charge transfer (LMCT) transitions [2,4]. We discuss the origins of the observed valence spectra differences between the two phases in relation to peaks shift, variations in occupancy, and variations in covalency as result of Mn valency changes occurring during lithiation. 1 M. K. Kinyanjui, P. Axmann, M. Mancini, G. Gabrielli, P. Balasubramanian, F. Boucher, M. Wohlfahrt-Mehrens, and U. Kaiser, Phys. Rev. Materials 1, 074402(2017) 2 J.M. Tarascon, E. Wang, F.K. Shokoohi, W.R. McKinnon, and S. Colson, J. Electrochem. Soc. 138, 2859 (1991) 3. J.B. Goodenough, and Y. Kim, J. Solid State Chem. 182, 2904 (2009) 4. D. M. Sherman, Am. Mineralogist 69, 788 (1984).

Resume : Anticipating a steadily increasing growth of the electric vehicle market, it appears of utmost importance to improve the environmental benignity of lithium-ion batteries (LIBs), while at least maintaining their performance metrics in terms of energy density, power capability, and reliability. In this regard, the use of entirely cobalt-free high-voltage LiNi0.5Mn1.5O4 (LNMO) would provide a great leap forward towards sustainable LIBs.[1,2] However, LNMO faces several severe challenges, including a rather poor cycling stability, continuous electrolyte decomposition at high potentials, and low compatibility with graphite anodes due to Mn-dissolution phenomena. Nevertheless, a rational material design can be applied to address these challenges and make LNMO a commercially competitive cathode material.[3,4] Herein, we present a scalable, optimized synthesis method to obtain LNMO particles with a tailored structure and morphology, providing an exceptional rate capability. The additional introduction of a MPOx coating further enhances the long-term cycling stability, in particular, for i) elevated cut-off potentials, ii) increased temperature, and iii) high dis-/charge rates, thus, allowing for the realization of high-power lithium-ion full-cells with more than 85% of their total capacity at 10C rate and >80% after about 1,000 cycles. References [1] S. Roberts, G. Gunn, in Crit. Met. Handb., John Wiley & Sons, 2013, pp. 122–149. [2] W. Li, B. Song, A. Manthiram, Chem. Soc. Rev. 2017, 46, 3006–3059. [3] H. Liu, J. Wang, X. Zhang, et al., ACS Appl. Mater. Interfaces 2016, 8, 4661–4675. [4] P. Axmann, G. Gabrielli, M. Wohlfahrt-Mehrens, J. Power Sources 2016, 301, 151–159.

Resume : We report on the atomic structure peculiarities derived from the advanced transmission electron microscopy (TEM) study of two classes of high energy density insertion materials. The first subject materials comprise the application of the Mg in the cathodes based on spinel and birnessite type magnesium oxides. The investigated MgMn2O4 spinel and (MgxNay)Mn2O4 birnessite phases possess high specific capacities of 130–100 mAh/g and 210 mAh/g, respectively. Upon galvanostatic magnesiation, both spinel and birnessite phases resembled their initial crystalline structures, however, leaving voids and defects behind with damage being more prominent in the birnessite. Further degradation of both materials initiated by those defects led to the battery failure through the permanent change of the crystal structure. The second class of investigated cathode martials is represented by the Li-rich oxyfluorides of Li1+xFeO2F type. The theoretical capacity values of these materials are in the range of 220-465 mAh/g. In our sturdy, we have for the first time successfully synthesized Li1.5FeO2F0.5 via ceramic synthesis (CS). Comparison with the conventional ball milling (BM) produced sample revealed, that the higher capacity of the CS sample is most likely attributed to the presence of structural defects. The presence of the defects was first suggested by XAS, and then thoroughly investigated by the TEM methods, such as electron energy loss spectroscopy and high angle annular dark field imaging.

Resume : Formation and annihilation of defects is an intrinsic and inseparable part of alkali cation (de)intercalation from positive electrodes (cathodes) for metal-ion batteries. Here we discuss antisite disorder in the olivine-structured LiFePO4, 3D framework or layered A2MPO4F (A = Li, Na, M = transition metal). We demonstrate that the bonding of the alkali metal cations to the semi-labile oxygen atoms is an important factor affecting electrochemical activity of alkali cations in the polyanion structures. Such semi-labile oxygens are not included into the M(O,F)6 octahedra, being tetrahedrally coordinated by one P and three alkali cations and forming localized sp3-hybridized states. Upon alkali cation deintercalation these oxygens experience severe undercoordination, causing an energy penalty for removing the alkali cations located in the proximity of such semi-labile oxygens. The importance of this semi-labile oxygens stems from their influence on the (de)intercalation mechanism, diffusion barriers and antisite defect formation. Dependence of the deintercalation potential of different alkali cation sites on the proximity to the semi-labile oxygens, charge compensation mechanism through the antisite Li/M disorder and associated changes in the deintercalation mechanism will be discussed. For LiFePO4 we establish the relation between antisite Li/Fe disorder and chemical substitution in the polyanion sublattice leading to unusual ?hydrotriphylite?-type solid solutions, altering the crystal structure and electrochemical capacity. The work was supported by RFBR (grant 17-03-00370).

Resume : Li-rich layered oxides, due to their superior specific capacities, have generated interest as positive electrode materials for Li-ion batteries. However, these compounds possess complex structural and electrochemical properties which has hindered its commercialization. This work undertakes a comparative study of two routinely employed synthesis methods for Li-rich layered oxides, and its effect on their structural, microstructural and electrochemical properties. Li2MnO3 (LMO), an archetypal Li-rich layered oxide, was synthesized through the conventional solid state ceramic method and the modified Pechini method. The reaction kinetics during synthesis and annealing was investigated through in-situ neutron diffraction, with further structural characterization performed through a combination of X-ray, neutron and electron diffraction techniques. This was complimented with stacking fault simulations, electron microscopy analysis and electrochemical studies. In addition to producing finer nano-sized particles, the LMO sample prepared through the modified Pechini method, showed an increased Li-Mn cation mixing and more broadening of the superstructure peaks. The latter can be interpreted as a higher faulting in the stacking of the layers. The samples also show different specific capacities owing to their different material properties, with the LMO sample prepared through the modified Pechini method showing significantly higher capacity in the first cycle. This study illustrates how synthesis methods affects the materials properties of Li-rich layered oxides, which we believe can be useful in synthesizing and optimizing similar compounds for cathode materials in Li-ion batteries.

Resume : Development of novel electrode materials for intercalation type batteries have in the past focused on highly crystalline materials with the capability to retain long-range order during cycling. However, recent years have seen an increased interest for disordered materials, e.g. with the discovery of multiple high capacity electrodes based on disordered rock-salt structures or even completely amorphous materials exhibiting higher capacities than their crystalline counterparts.[1] Furthermore, it was recently showed by Ceder et al that long-range order is not a prerequisite for maintaining percolating intercalation pathways.[2] Still very little is known about the structural mechanisms behind order-disorder transitions induced by ion-intercalation or about ion-storage mechanisms in disordered materials. Using a combination of operando synchrotron X-ray scattering, electron microscopy and electrochemical analysis, we have studied a series of disordered and amorphous electrode materials such as nano-rutile TiO2, V2O5, MnOx.[4] This allows us to map out the structural evolution during battery charge and discharge at the atomic- and nano-scale, and begin to understand the ion-storage mechanisms in such materials. In this presentation, we will focus on results which demonstrate the different types of order-disorder phenomena (e.g. topotactic, reconstructive, domain size reduction) and ion-storage mechanisms (e.g. solid solution, two-phase transition) we have encountered. [1] a. J. Lee et al., Nature 2018, 556, 185-190. b. E. Uchaker et al., J. Mater. Chem. A 2014, 2, 18208-18214. [2] J. Lee et al., Science 2014, 343, 519-522. [3] C. K. Christensen et al., Chem. Mater. (2019) DOI: 10.1021/acs.chemmater.8b04558.

Resume : The increasing demand of energy along with the challenge to reduce the dependency on fossil fuels, lead to the need to use renewable energy sources. These systems generate fluctuating energy, and thus energy storage technologies are needed. Li ion batteries (LIBs) lead the secondary battery market, but concerns about the consequences of a growing demand of Li leads the search for alternative technologies. Owing to their chemical similarities Na ion battery (SIB) research is growing as a potential alternative. Among candidate cathode active materials for SIBs, transition metal layered oxides (TMOs) are attractive due to their low cost, non-toxicity and good theoretical electrochemical characteristics. However, their structural stability at charged state is a limiting factor, which is believed to be related to irreversible TM migration into Na layers. Yet, experimental evidence as well as studies of its influence on the electrochemistry are scarce, although it is a key step to develop better performing TMOs. In order to better understand this phenomenon, NaFeO2 was studied as model system. Using in-situ XRD it was possible to track Fe migration upon cycling and observe its influence on Na diffusivity. Unexpectedly, at intermediate potentials the Fe migration appears to be partially reversible. This suggests that the process might not be as well understood as it seems; controlling the reversibility of the TM might constitute a novel route for the optimization of these materials.

Resume : In the toolkit of the materials scientist, solution-based methods offer a broad panel of possibilities for the synthesis of electrode materials. However, the undoubted fact that powders prepared from solutions frequently surpass their solid-state-reacted competitors does not mean that solution-based methods are always the best option: issues such as cost, up-scalability or packing density can tilt the balance away from the advantages of favourable microstructure or lower temperature/duration of heat treatment. Solution-based techniques are at their most competitive when they remove roadblocks to new phases/microstructures or ensure reproducibility and homogeneity in the synthesis of complex compositions. Here we focus on one of the key aspects of the selection/design of a solution-based synthesis: to what extent the excellent homogeneity in the solution can be retained in the solid precursor. Our work relies on the characterization of samples at different stages (solution, precursor, heat-treated powder and electrode material) through compositional, structural, microstructural and electrochemical techniques. Examples will include our recent results on the successful synthesis of the elusive Na2Fe2(SO4)3 stoichiometric alluaudite phase through a tailored reverse-strike coprecipitation, and a discussion of how to deal with risks of sequential precipitation in evaporating droplets based on our results on the spray drying of various phosphate and fluorophosphate compositions.

Resume : Lithium rich oxyfluoride materials with a disordered rock salt structure represent a new class of high energy density cathodes for Li-ion batteries. Improved energy density is based on higher operating voltages vs. their oxide analogues and increased ratio between lithium and transition metal. Lithium is stored in the vacating lattice sites of the material and its diffusion is facilitated with disorder and presence of defects in the structure. This is the main reason why first results reported in the literature used mechanochemical synthesis for the preparation of Li2VO2F. [1] Here we show that lithium rich oxyfluoride materials can be synthesized by ceramic route. [2] The obtained material crystalize in FCC (Space group N° 225). Different levels of doping contribute to the different degree of disorder and hence to differences in the electrochemical properties. Synthesis, structural properties and electrochemical storage mechanism will be discussed on the base of Li1+xFeO2Fx family of materials. [1] R. Chen, S. Ren, M. Knapp, D. Wang, R. Witter, M. Fichtner, and H. Hahn, ?Disordered lithium-rich oxyfluoride as a stable host for enhanced Li+ intercalation storage,? Adv. Energy Mater., vol. 5, no. 9, 2015. [2] J.-M. Ateba MBA, I. Arcon, G. Mali, E. Tchernychova, R. Witte, R. Kruk, R. Dominko, Ceramic Synthesis of Disordered Lithium Rich Oxyfluoride Materials, submitted. Acknowledgement: This work has received funding from the European Union?s Horizon 2020 projects LiRichFCC (No 711792) and CALIPSOplus (No. 730872) and from the Slovenian Research Agency research programs (P2-0393, P1-0112). We acknowledge access to the SR facilities of ELETTRA (beamline XAFS, pr. 20175158).

Resume : Lithium cobalt phosphate LiCoPO4 (LCP) has been a strong candidate as a high voltage positive electrode in lithium-ion batteries. However, poor electrochemical performance has been a major obstacle to its wide application. Here, we will present two approaches to overcome these limitations: use of aqueous binders in LCP electrodes and magnesium (Mg) doping in LCP. The first strategy shows significantly improved electrochemical performance by using the aqueous binder, sodium carboxymethyl cellulose (CMC). The CMC not only provides a uniform electrode surface but also suppresses degradation of LCP by scavenging HF in the electrolyte solution. In comparison with other water-soluble binders, the homogeneous distribution of CMC within the electrodes accompanied by high accessibility of carboxylate groups in CMC are shown to be crucial factors to achieve enhanced performance.[1] The second approach reveals that Mg-doped LCP exhibits enhanced cycling performance. Structural investigation of Mg-doped LCP using combined powder neutron and X-ray diffraction reveals a decrease in anti-site defects. In addition, the reduced unit cell volume variation during the charging process is observed by in-situ XRD. Morphology and surface studies show the presence of a Mg-rich layer on the surface that might prevent harmful reactions with the electrolyte. The combined beneficial effects of Mg-doping in LCP result in improved capacity retention. 1. Kim, E. J.et al., J. Power Sources, 403, 11, 2018

Resume : Some intercalation-type electrode materials undergo an irreversible loss of crystallinity upon Li-intercalation. An example of such a material is orthorhombic V2O5, which loses long range order upon intercalation of >2 Li.[1] Very little is presently known about the mechanism of either disordering or ion-storage in this material during subsequent charge-discharge cycles. This is in spite of several studies showing that disordered LixV2O5 can provide ∼310 mAh/g stable reversible capacity when cycled between 1.5 and 3.8 V, which exceeds the capacity of, e.g., LiCoO2 and even “Li-rich LiNixCoyMn1−x−yO2 (NMC)” (240 and 280 mAh/g,[2] respectively). We have investigated the structural evolution during Li-insertion and -extraction in deep discharged V2O5 electrodes by means of combined ex situ and operando synchrotron radiation powder X-ray scattering and pair distribution function analysis.[3] We find that, the crystalline domain size decreased drastically from >2000 Å to ~60 Å when three Li is inserted, and that the resulting disordered ω-Li3V2O5 rock salt structure has a local dispersed cation ordering within the ccp oxygen lattice. The domain size of this cation ordering is estimated to 10-15 Å. The charged phase has very short range order, 10-15 Å, and is best described as the β LixV2O5 built on edge and corner sharing [VO6] octahedra linked by corner sharing [VO5] square pyramids. References: [1] C. Delmas, et al., Solid State Ionics 69 (1994) 257-264. [2] P. Rozier et al., J. Electrochem. Soc., 162 (2015) A2490−A2499. [3] C. K. Christensen et al., Chem. Mater. (2019) DOI: 10.1021/acs.chemmater.8b04558

Resume : Vanadium-based compounds have attracted great attention as positive electrode materials for Li-ion batteries. This is due to vanadium’s ability to display a range of oxidation states making it one of the most susceptible 3d-metals to undergo multi-electron transfer processes. A well-known example is the electrode material LiVOPO4 which demonstrates both the V(V)/V(VI) and V(IV)/V(III) redox couples during Li+ extraction and insertion.[1] One technique used to reach higher potentials is to replace the polyanion with a more electronegative species. For example, the (PO4)3- in the Li4VO(PO4)2 phase has been replaced with the (SO4)2- to yield the Li2VO(SO4)2 phase.[2,3] Despite this, vanadium-based materials utilising the (SO4)2- polyanion remain underexplored, presumably due to their air sensitivity. Here, we present the modified low-temperature synthesis and electrochemical performance of the A2O-V2O5-SO3 (A = K, NH4) systems, not previously used as electrode materials for Li-ion batteries. [1] M. Bianchini, J. M. Ateba-Mba, P. Dagault, E. Bogdan, D. Carlier, E. Suard, C. Masquelier and L. Croguennec, J. Mater. Chem. A, 2014, 2, 10182–10192. [2] M. S. Kishore, V. Pralong, V. Caignaert, U. V. Varadaraju and B. Raveau, Electrochem. commun., 2006, 8, 1558–1562. [3] M. Sun, G. Rousse, M. Saubanère, M.-L. Doublet, D. Dalla Corte and J.-M. Tarascon, Chem. Mater., 2016, 28, 6637–6643.

Resume : Growing energy demand and concerns related to the depletion of lithium resources are main driving forces to the search for affordable alternatives to lithium-ion batteries. In this sense, sodium-ion batteries (SIBs) are currently receiving considerable attention due to the abundance of sodium metal in the Earth?s crust. Owing to the high interplanar distances and available storage places arising from their disordered structures, hard carbons are the preferred anode material so far. However, despite the large number of publications in this area, the role of microstructure and crystallinity changes with the treatment temperature in the sodium insertion mechanism in hard carbons is not fully understood In this work we report on the evaluation of the microstructural changes of hard carbons from olive stones carbonization at different temperatures using total scattering synchroton X-ray diffraction measurements and their analysis in real space using the atomic pair distribution function formalism. The electrochemical behavior of these materials as anodes for SIBs are evaluated as a function of treatment temperature, aiming at establishing a relationship between structural order and achievable capacities.

Resume : In the Era of IoT, wearable electronics is a hot topic with an expected market growth from $13.2 billion in 2017 to $98.2 billion in 2026. Smart e-textiles with embedded electric circuits have arisen a lot of attention since they provide extra comfort to the user. However, they still have power supply constraints, being urgent to develop wearable energy sources. Supercapacitors (SCs) are promising energy storage devices for wearables and printable electronics due to their high power density, fast charge rates, long cycle lifetime and safety. Carbon-based nanomaterials are of particularly relevant for the design of wearable/flexible SCs due to their high surface area, good electrical conductivity, flexibility, mechanical stability and lightness. Herein, we report the fabrication of two carbon-based SCs directly on flexible substrates by advanced scalable and high-tech processes using a solid-gel electrolyte: a) a textile SC on cotton by a scalable textile industry process; b) a micro-SC on PET by high-tech lithography. Both SCs showed excellent performance, with working voltages of ~2 V and specific capacitances of 8.01 F/g and 6.65 F/cm3 for the textile and micro SC, respectively, resulting in energy densities of 18.24 Wh/kg and 3.70 mWh/cm3 and power densities of 2.72 kW/kg and 1.49 W/cm3. The influence of the electrodes features and device geometry on the performance of the SCs when feeding wearable electronics and the most suitable textile applications will be discussed. Acknowledgements: Work funded by FEDER through COMPETE 2020 and by Portuguese funds through FCT/MEC under Program PT2020 in the framework of the projects PTDC/CTM-TEX/31271/2017, UID/QUI/50006/2013-POCI/01/0145/FEDER/007265 and UID/NAN/50024/2013. CP thanks FCT for Investigator contract IF/01080/2015. RSC thanks UniRCell Project (POCI-01-0145-FEDER-016422) for a MSc. grant.

Resume : This presentation discusses an unconventional electrode concept to reversibly store ions. The conventional approach for storing charge in rechargeable sodium-ion batteries is to use solid electrodes and liquid electrolytes. During charging and discharging, the charge transfer between the liquid electrolyte and solid electrode involves stripping of the solvation shell. Here, we discuss an alternative approach based on the intercalation of solvated ions. We show that this process is highly reversible and the redox potential can be tuned by the type of solvent. This mechanism leads to large volume expansion yet excellent cycle life is found. At the same time, the concept challenges the necessity for an SEI. We show that the redox behavior is highly dependent on temperature and new electrode reactions can be activated at higher temperature, e.g. using pentaglyme as solvent does not lead to any appreciable capacity at room temperature but full capacity is obtained above 45 °C. [1] P.K. Nayak, L. Yang, W. Brehm, P. Adelhelm, Angew. Chemie Int. Ed. 57(1) (2018) 102-120. [2] M. Goktas, C. Bolli, E. J. Berg, P. Novak, K. Pollok, F. Langenhorst, O. Lenchuk, D. Mollenhauer, P. Adelhelm, Adv. Energy Mater. 8(16) (2018) 1702724. [3] B. Jache, P. Adelhelm, Angew. Chemie Int. Ed. 53(38) (2014) 10169-10173. [4] M. Goktas, B. Akduman, P. Huang, A. Balducci, P. Adelhelm, J. Phys. Chem. C, 122(47) (2018) 26816-26824

Resume : With respect to the future development of battery technologies, one has to keep in mind that there will not only be one type of battery, but ? as today ? most likely different storage technologies available at the market in parallel. This is related to the broad diversification of different applications (e.g. portable electronics, electro mobility, home storage) and their versatile requirements for energy storage. The broad diversification in battery applications leads also to a wide diversification in current battery research directions and results in the development of various alternative storage technologies besides state-of-the-art lithium ion batteries (LIBs). These alternative technologies focus on future key parameters such as low cost, sustainability and material availability and include e.g. sodium-ion batteries, potassium-ion batteries as well as the so-called ?dual-ion batteries? (DIBs).The DIB technology, and in particular the dual-graphite or dual-carbon battery, has gained much attention in the battery research community, as this emerging storage technology is considered to have benefits in terms of material availability, sustainability as well as cost and safety compared to LIBs. The term ?DIB? summarizes a broad range of different cell chemistries, which can be distinguished according to their electrolyte active species and/or active host materials. Various DIB cell chemistries, have already been reported, i.e. based on lithium, sodium, potassium, aluminum or calcium. Here, novel strategies and challenges for the development of sustainable DIB technologies with focus on intercalation chemistry, advanced materials and fundamental knowledge gain in terms of the charge/discharge mechanism and possible degradation mechansims are discussed.

Resume : In the development of wearable energy devices, polypyrrole (PPy) is considered as a promising electrode material owing to its high capacitance and good mechanical flexibility. Herein, we report a PPy-based hybrid structure consisting of vertical PPy nanotube arrays and carbon nano-onions (CNOs) grown on textile for wearable supercapacitor. In this hybrid nanostructure, the vertical PPy nanotubes provide straight and superhighways for electron and ion transportation, boosting the energy storage, while the CNOs mainly act as the conductivity retainer for the underlayered PPy film during stretching. A facile template-degrading method is developed for large-area growth of the PPy-based hybrid nanostructures on the textile through one-step polymerization process. The stretchable supercapacitor fabricated by this PPy-based hybrid nanostructure on textile exhibits superior energy storage capacitance with a specific capacitance of 64 F g-1. Also, the stretchable supercapacitor presents a high capacitance retention of 99% at a strain of 50% after 500 stretching cycles. Furthermore, we demonstrate that the textile-based stretchable supercapacitor device can provide a stable energy storage performance in different wearable situations for practical applications. The use of the PPy-based hybrid nanostructures as supercapacitor electrode offers a novel structure design and a promising opportunity for wearable power supply in real applications.

Resume : The performance of the energy storage and conversion devices is predominantly determined by the properties of the carbon, but it is not yet clear which of the structural feature of the carbon, i.e., specific surface area, pore size or pore size distribution is the decisive parameter [1-4]. Small Angle X-Ray and Neutron Scattering (SAXS and SANS) techniques are well-suited to address structural changes that might occur due to structural transition with increasing temperature of the synthesis or due to an added binder. In particular, the accessibility of the pores is a central question inasmuch as it determines the electrochemical performance [5-6]. The model-free analysis by SAXS developed based on earlier fundamental works of Schiller, Méring [7] or Méring and Tchoubar [8], Perret and Ruland and co-workers [9,10] will be introduced. A full elucidation of the microstructure of nanoporous RP-20 carbon powder, and of the electrodes made from RP-20 powder mixed with polytetrafluoroethylene binder will be presented. The detailed structural information will be compared with the data established for micromesoporous carbide derived carbons. The model-free analysis by SAXS shows that the scattering contributions from the lateral disorder and the pore scattering could be separated. The slit-like shape of the pores and several other important structural characteristics of nanostructure of pores in carbon materials could be obtained. A good agreement between the results obtained from different characterization techniques was achieved. The analysis by SAXS shows that a 6 wt% amount of polytetrafluoroethylene does not change the micropore structure of the carbon. SANS together with contrast matching liquids allows us to see whether a given liquid accesses pores. References [1] M. Eikerling, A.A. Kornyshev, E. Lust, Optimized Structure of Nanoporous Carbon-Based Double-Layer Capacitors, J. Electrochem. Soc. 152 (2005) E24?E33. [2] L. Borchardt, M. Oschatz, S. Paasch, S. Kaskel, E. Brunner, Interaction of electrolyte molecules with carbon materials of well-defined porosity: characterization by solid-state NMR spectroscopy, Phys. Chem. Chem. Phys. 15 (2013) 15177. [3] A. Nikitin, Y. Gogotsi, Nanostructured Carbide-Derived Carbon, Encycl. Nanosci. Nanotechnol. (2003). [4] V. Presser, M. Heon, Y. Gogotsi, Carbide-Derived Carbons - From Porous Networks to Nanotubes and Graphene, Adv. Funct. Mater. 21 (2011) 810?833. [5] E. Härk, A. Petzold, G. Goerigk, M. Ballauff, U. Keiderling, R. Palm, I. Vaas, E. Lust, B. Kent, U. Keiderling, R. Palm, I. Vaas, E. Lust, The effect of a binder on porosity of the nanoporous RP-20 carbon. A combined study by small angle X-ray and neutron scattering, Microporous Mesoporous Mater. 275 (2019) 139?146. [6] E. Härk, A. Petzold, G. Goerigk, S. Risse, I. Tallo, R. Härmas, E. Lust, M. Ballauff (2019). Carbide Derived Carbons Investigated by Small Angle X-ray Scattering: Inner Surface and Porosity vs. Graphitization. Carbon (paper under revision) [7] C. Schiller, J. Mering, Diffusion centrale des rayons X par des carbones graphitables. Déviation de la loi de Porod., C. R. Acad. Sc. Paris - Ser. B. 264 (1967) 247?250. [8] J. Méring, D. Tchoubar, Interprétation de la diffusion centrale des rayons X par les systèmes poreux. I, J. Appl. Crystallogr. 1 (1968) 153?165. [9] W. Ruland, B. Smarsly, research papers X-ray scattering of non-graphitic carbon?: an improved method of evaluation research papers, J. Appl. Crystallogr. 35 (2002) 624?633. [10] W. Ruland, Apparent fractal dimensions obtained from small-angle scattering of carbon materials, Carbon N. Y. 39 (2001) 323?324.

Resume : Aqueous Na-ion batteries are believed to be a promising energy storage solution for stationary applications. The water-in-salt strategy enables the use of aqueous electrolytes in an extended potential range (> 2 V), which requires the investigation of optimized electrode materials.[1,2] Manganese carbonophosphates are an auspicious class of materials. [3] In organic-based electrolytes, the variant Sidorenkite Na3MnPO4CO3 (NMPC) showed a specific charge of 125 mAh/g when tested as cathode material in Na-ion batteries.[4] However, conventional NMPC proved to be unstable in water-in-salt electrolytes, since electrochemical cycling led to amorphization of the material and carbonate decomposition already during the first desodiation. We found that a partial substitution of Mn atoms by Co in Na3Mn1-xCoxPO4CO3 (NMCPC) increased the stability of the material in aqueous system. To understand this improvement, materials with different ratios of Co/Mn were synthesized and characterized. The influence of cobalt in NMCPC cathodes was assessed by operando X-ray diffraction, X-ray absorption spectroscopy and online electrochemical mass spectrometry as well as conventional electrochemical measurements. Literature: [1] L. Suo, Science, 350 (2015) 938. [2] Y. Yamada, Chemistry Letters, 46 (2017) 1056-1064. [3] H. Chen, J. Am. Chem. Soc., 134 (2012) 19619-19627. [4] H. Chen, Chemistry of Materials, 25 (2013) 2777-2786.

Resume : Since its first commercialization in the early 1990?s, the Li-ion batteries (LIB) technology has spurred the spread if portable electronics as well as enable the realization of electrical vehicles with a reasonable driving range. Nevertheless, challenges still remain concerning the capacity of LIBs to enable the use of renewable energy to the grid while minimizing its footprint on Nature. Hence, sustainability and cost are becoming overriding factors to consider. Toward that goal, aqueous electrolytes could provide a lower-cost, safer and non-toxic alternative to organic electrolytes, providing that the overall battery performances are optimized for long-term application. Started in 1994, the quest for aqueous batteries quickly showed limitations owing to the poor energy density of such system, which is limited by the narrow electrochemical window of water (1.23 V) when compared to organic electrolytes. Recently, the use of highly concentrated water-in-salt aqueous electrolytes was proposed to operate at potentials greater than 3 V. While this finding has attracted lots of excitements, questions remain regarding 1) the origin for such increase of the electrochemical window as well as 2) the long-term efficiency of such systems. Adopting an approach used by the electrocatalysis community,1,2 we will discuss the role of water solvation on the electrochemical reduction of water. Furthermore, along our quest for decreasing the amount of expensive salt used in superconcentrated electrolytes, we observed an unusual phenomenon, namely the formation of an Aqueous Biphasic System (ABS) in which two aqueous phases are non-miscible. We will discuss the use of such aqueous biphasic electrolytes for the development of dual ions batteries. References: 1- Dubouis, N., Serva, A., Salager, E., Deschamps, M., Salanne, M. and Grimaud, A.* The fate of water at the electrochemical interfaces: electrochemical behavior of free water vs. coordinating water, Journal of Physical Chemistry Letters, 9, 6683-6688, 2018. 2- Dubouis, N., Lemaire, P., Mirvaux, B., Salager, E., Deschamps, M. and Grimaud, A.* The role of hydrogen evolution reaction on the solid-electrolyte-interphase formation mechanism for ?Water-in-Salt? electrolytes, Energy and Environmental Science, 11, 3491-3499, 2018.

Resume : With a worldwide trend towards the efficient use of renewable energies and the rapid expansion of the electric vehicle market, the importance of rechargeable battery technologies, particularly lithium ion batteries, has steadily increased. In the past few years, a major breakthrough in electrolyte materials was achieved by simply increasing the salt concentration in suitable salt/solvent combinations, offering technical superiority in numerous figures of merit over alternative materials. This long-awaited extremely simple yet effective strategy can overcome most of the remaining hurdles limiting the present lithium ion batteries without sacrificing manufacturing efficiency, and hence, its impact is now widely felt in the scientific community, with serious potential for industrial development. I will try to provide timely and objective information that will be valuable for designing better realistic batteries, including a multi-angle analysis of their advantages and disadvantages together with future perspectives. Emphasis is placed on the pathways to address the remaining technical and scientific issues rather than re-highlighting the many technical advantages.

Resume : Understanding the formation of the SEI layer is a key-point for improving the lifetime of Li-ion batteries for the automotive industry, as well as design novel anode materials with improved properties. We investigate the SEI formation on the single crystal metal facets in an organic aprotic electrolyte, by combining idealized experiments with realistic quantum mechanical simulations of the interface. We find that the measured overpotential is related to stabilizing the active structure of the interface having Li+ adsorbed and correlates with the work function of the electrode surfaces. Li+ facilitates the dissociation of HF, which is the source of proton, to form LiF and H2. If negatively charged proton sources are involved, a cation at the interface facilitates the reaction kinetics. When the proton source is an acid there is no negatively charged intermediate and the hydrogen evolution proceeds at much lower overpotentials. This reveals a situation where the overpotential for electrocatalysis is related to stabilizing the active structure of the interface, facilitating the reaction rather than providing the reaction energy. This has implications for the SEI formation in Li-ion batteries and for reduction reactions in alkaline environment as well as for design principles for better electrodes.

Resume : Olivine-NaFePO4 is one of the most attractive materials for sodium ion batteries, since its exhibits one of the highest reversible capacities reported up to date for a polyanionic Na-ion cathode material (154 mAh g-1) and maintains some of the exceptional features of LiFePO4[1], its Li counterpart: reaction within a narrow voltage range inside the voltage stability window of the electrolyte, good stability and good cyclability[2,3]. Since the thermodynamically stable of NaFePO4 phase is maricite[4], which has a poor electrochemical performance[5], the only reported way to obtain olivine-NaFePO4 with potential industrial interest is from chemical extraction of lithium from LiFePO4, followed by the insertion of sodium. Up to this date, this process has been performed using expensive and toxic reagents[2,3]. In this work, a novel easy synthesis route for olivine NaFePO4 using low-cost and environmentally-friendly reagents and the further recovery of lithium will be presented. The electrochemical performance of the obtained material will be shown, with a discharge capacity that stabilizes around 125 mAhg-1 and a coulombic efficiency of 99%. 1. A. Padhi et al. J. Electrochem. Soc. 1997, 144, 1188. 2. P. Moreau et al. Chem. .Mater. 2010, 22, 4126. 3. M. Casas-Cabanas et al. J. Mater. Chem. 2012, 22(34), 17421. 4. Y. Le Page et al. Can. Miner. 1977, 15, 518. 5. J. Kim et al. Energy Environ. Sci. 2015, 8, 540.

Resume : Design of safe lithium ion batteries require innovations in materials for cathodes, anode and electrolytes. In particular the role of 2D materials can be significant to boost the safety. This presentation provides an overview on the efforts in the PI's lab to design thermally safe high energy density batteries. At first, I will show how the thermal stability of cathodes can be improved by encapsulation of electrode particles within graphene materials. The cyclic performance of commercially cathode electrodes was improved by 100%. We also showed that the surface degradation can be significantly reduced by TEM-EELS measurements. We also will discuss how 2D materials can make the solid electrolytes to cycle better in Li-metal batteries. In particular the enhanced surface interactions of 2D materials can be a major factor to increase salt dissociation resulting in the increase of the concentration of mobile ions to enhance the ion conductivity in solid electrolytes. At the end, I will show the effect of graphene oxide coating on glass fiber separators as a novel means to combat lithium dendrites.

Resume : Solid polymer electrolytes (SPEs) have been emerging as attractive candidates for meeting the demand in safe and high energy density batteries, attributed to their low flammability and ease in process. However, ionic conductivities of SPEs are several orders of magnitude lower than those of the conventional liquid electrolytes, hence preventing ambient-temperature operation of all solid-state lithium polymer batteries (ASSLPBs). Moreover, SPEs with low glass transition temperature (Tg) and low crystallinity, essential to speed up the ionic transport, can barely form self-standing membranes. To overcome above-mentioned limitations, extensive work has been devoted to the search of polymeric matrices that could allow the obtaining of SPEs with improved ionic conductivity at room temperature and good mechanical properties. Among which, chemical modification such as cross-linking or copolymerization are the main used strategies. In this talk, the physicochemical and electrochemical properties of our recently developed SPEs are presented. In particular, a new type of flowable polymer electrolyte (FPE) comprising of a variation of our recently presented super soft polymer matrix and sulfonamide salts. This new FPE has been used as buffer layer with the aim of improving the interfacial compatibility of PEO-based SPEs with Lio electrode. Notably, the Lio || LiFePO4 cells using the FPE can enhance the electrochemical performance compared with the ones using plain PEO based SPEs.

Resume : We developed boron-hydrogen based compounds such as compounds containing borohydrides (M(BH4)x, M=Li, Na, Mg, ?) or closo-borates (Mx(ByHy), y=10, 12) as solid-state electrolytes with liquid-like sodium and lithium conductivity at room tem-perature. In particular, the later allowed for the stable cycling of a stable 3 V all-solid-state sodium?ion battery using the mixed anion compound Na4(B12H12)(B10H10) as electrolyte. We achieved a capacity of 85 mAh/g at C/20 and 80 mAh/g at C/5 with more than 90% capacity retention after 20 cycles at C/20 and 85% after 250 cycles at C/5 [1,2]. With this battery, boosting the voltage and the cycling stability of previous proof-of-concept batteries, we establish the family of closo-borates as an alternative to the existing classes of sulfide and oxide based ionic conductors employed as solid-state electrolytes in all-solid-state batteries. On the basis of this battery, we discuss the opportunities and challenges of this family of electrolyte in terms of ionic conduction, electrochemical stability, interfacial contact, and synthetic approaches. Acknowledgement: Financial support by the Swiss National Science Foundation for the Sinergia project ?Novel ionic conductors? under the contract number CRSII2_160749/1 is gratefully acknowledged [1] L. Duchêne et al., Chem. Commun., 2017, 53, 4195. [2] L. Duchêne et al., Energy Environ. Sci., 2017, 10, 2609

Resume : Over the last years, an increasing number of studies have been dedicated to the research and development of various classes of solid-state electrolytes. New materials have emerged enriching the diversity of the type of solid-state battery concepts. Indeed, besides the classical sulfidic, oxidic and polymer type solid-state battery systems, several concepts based on hybridization of materials and technologies have been proposed [1, 2]. While obviously the ionic conductivity of the Li-ion conductor is a pre-requisite to enable all solid-state battery, other criteria such as stability and compatibility of electrode materials and their integration in the cell are also needed. In this presentation we will give an overview of the different solid electrolyte materials comparing their advantages and limitations in this respect and will discuss further on the remaining challenges to be solved. Finally, a special insight in the imec solid nanocomposite electrolyte and performances will be given. [3] [1] Z. Zhang, Y. Shao, B. V. Losch, Y. Hu, H. Li, J. Janek, C. Nan, L. Nazar, J. Maier, M. Armand, L. Chen, Energy Environ. Sci. 2018, DOI: 10.1039/C8EE01053F [2] M. Keller, A. Verzi, S. Passerini, DOI: 10.1016.j.powsour.2018.04.0999 [3] ECS AiMES 2018, A06-0470, P. Vereecken, X. Chen, K. Gandrud, B. Put, A. Sagara, M. Murata, M. Tomiyama, Y. Kaneko, M. Shimada, J. Steele, M. Roeffaers, M. Debucquoy, M. Mees

Resume : As the demand for higher energy density drives a transition from Li- or Na-ion batteries to metal based anodes the urgency to develop safer high performane electrolytes increases. Anode protecting solid electrolyte membranes or complete replacement of flammable liquids in all solid state batteries appear as promising alternatives to flammable liquid electrolytes. This requires the identification of kinetically stable fast ionic conductors that can be processed at competitive cost and scale and are compatible with the other battery components. Here we discuss a systematic route to identify such solid electrolytes that ensure high rate performance based on the high mobility of alkali ions in various framework oxides and chalcogenides. As an example we will discuss the novel Na3MX4 ?Na4SnX4 phases (M= P, Sb; X= S, Se) including the fastest Na-ion conducting sulfide Na11Sn2PS12. Large-scale energy storage devices also place stringent demands on materials processability. Compared to brittle ceramics, polymer composites enable scalable continuous production of tough ultrathin membranes. Mixing NASICON-type solid electrolytes with acrylate photopolymers allow for fast membrane curing and closer control on thicknesses compared to conventional solvent-evaporation casting and can be integrated more straightforwardly into additive manufacturing processes. Dense photopolymer composite membranes with well-controlled thicknesses down to 30 ?m are fabricated in seconds. They show markedly enhanced toughness and higher temperature tolerance. Promising ionic conductivities above 10^-5 S/cm are achieved. The use of the membranes in various lithium-metal based battery architectures is demonstrated.

Resume : The lithium phosphidosilicates1-3 are an interesting new class of potential solid Li electrolyte materials. These systems are made up of a complex framework comprised of (Si4P1014?) corner-sharing ?super-tetrahedra?, between which the lithium cations are accommodated. The high anionic charge on the super-tetrahedral framework allows for a large number of charge compensating lithium ions to be present in the system. Experimentally, this results in very low energy barriers to lithium diffusion, within the region of 0.1 eV or below, with ionic conductivities of approximately 6×10?6 Scm?1.1,2 As a result, the lithium phosphidosilicates are a promising new class of materials for solid state lithium ion batteries. In this work, we have focused on the system Li2SiP2 (LSP)1,2 and studied both the lithium diffusion and doping properties using density functional theory (DFT). We find that trivalent cation dopants prefer to occupy the silicon site rather than the lithium site. The most favourable being Al doping. This is similar to observations in oxide zeolite materials.4 Ab initio molecular dynamics (AIMD) calculations on both pure and 10% Al doped LSP, imply increased lithium ion diffusion at temperatures below 700 K in the doped LSP system. The nudged elastic band (NEB) calculations elucidate a lithium interstitial mechanism as the most favourable low energy barrier pathway. The use of dopants primes these pathways and enables improved lithium conductivity at lower temperatures. References: [1] A. Haffner, T. Bräuniger, D. Johrendt, Angew. Chem., Int. Ed. 55 (2016) 13585-13588. [2] L. Toffoletti, H. Kirchhain, J. Landesfeind, W. Klein, L. van Wüllen, H. A. Gasteiger, T. F. Fässler, Chem. ? Eur. J. 22 (2016) 17635-17645. [3] H. Eickhoff, L. Toffoletti, W. Klein, G. Raudaschl-Sieber, T. F. Fässler, Inorg. Chem. 56 (2017) 6688-6694. [4] P.A. Jacobs, E.M. Flanigen, J.C. Jansen, H. van Bekkum, Introduction to zeolite science and practice, second ed., Elsevier, 2001.

Resume : All-solid-state batteries promise to simultaneously yield higher energy density, improved safety, and lower cost as compared to state-of-the-art lithium-ion technologies based on organic liquid electrolytes. A competitive all-solid-state battery requires a solid-state electrolyte with high ionic conductivity near room temperature, combined with high thermal and electro-chemical stability. Meeting these three requirements simultaneously represents a major challenge. Here we present a new sodium-ion conductor in the closo-borate family, namely Na2(B12H12)0.5(B10H10)0.5, that simultaneously offers high sodium-ion conductivity of 0.9 mS/cm at 20 °C, excellent thermal stability up to 450 °C, and importantly a large electro-chemical stability window of 3 V including stability versus metallic sodium enabling the use of a sodium metal anode. [1] Using a solution-based impregnation method to create a stable contact at the interface between cathode material and solid-state electrolyte, we demonstrate that Na2(B12H12)0.5(B10H10)0.5, can be implemented in a 3 V all-solid-state sodium-ion battery consisting of a sodium metal anode and a NaCrO2 cathode. The cell shows high cycling stability and good rate performance with more than 85% capacity retention after 250 cycles at C/5. [2] We further discuss approaches for inexpensive and scalable synthesis of closo-borate compounds. [1] L. Duchêne et al., Chem. Commun., 2017, 53, 4195. [2] L. Duchêne et al., Energy Environ. Sci., 2017, 10, 2609

Resume : Growing global concern over pollution and steady usage of rapidly dwindling fossil fuels and non-renewable energy sources has attracted global scientific attention. To address these burning issues, there is an inevitable need to harness renewable energy sources. Renewable energy sources are intermittent, which warrants complementary energy storage devices to store energy as and when generated. In this sector, rechargeable batteries play a vital role. The energy stored in form of chemical potential can be used continuously. From the past three decades, wide range of materials have been studied for battery applications. However, manganese-based materials have a special position with attractive qualities like low-cost, environmental friendly nature, non-toxic and multiple oxidation states to design high-energy density materials1. Accordingly, several Mn-based cathodes like LiMn2O42 and LiNi1/3Mn1/3Co1/3O2 (NMC)3 have been commercialized. Manganese-based layered materials are promising owing to their resource-friendly, low-cost, non-toxic nature with high operational safety. Here, Na-Mn-O ternary layered metal oxide (Na2Mn3O7) was synthesized using a single-step conventional solid-state synthesis.4-7 The pure phase Na2Mn3O7 crystallizes in triclinic structure (s.g. P-1). It consists of Mn in 4+ oxidation state with electrochemically active Mn4+/Mn3+ redox center. The as-synthesized black powder worked as a robust cathode for the Li-, Na-, K- and Zn-ion batteries. It delivered a reversible capacity of ~160, ~140, ~134 and ~330 mA h g-1 respectively with Li, Na, K and Zn metal as anode in half-cell architecture. Interestingly, Li-ion battery exhibited solid-solution type (de)intercalation upon the variation of Li-ion concentration in Na2AxMn3O7 whereas Na and K-ion (de)intercalation involve two-phase redox reaction. References 1. Thackeray M, David W, Bruce P, Goodenough J. (1983) “Lithium insertion into manganese spinels.” Mater. Res. Bull., 18, 4, 461. 2. Thackeray M, Johnson P, De Picciotto L, Bruce P, Goodenough J. (1984) “Electrochemical extraction of lithium from LiMn2O4.” Mater. Res. Bull., 19, 2, 179. 3. Johnson C. S, Li N, Lefief C, Vaughey J. T, Thackeray M. (2008). “Synthesis, characterization and electrochemistry of lithium battery electrodes: xLi2MnO3·(1-x) LiMn0. 333Ni0. 333Co0. 333O2 (0≤ x≤ 0.7).” Chem. Mater., 20, 19, 6095. 4. Sada K, Senthilkumar B, Barpanda P. (2018). “Layered Na2Mn3O7 as a 3.1 V Insertion Material for Li-Ion Batteries”. ACS Appl. Energy Mater., DOI: 10.1021/acsaem.8b01551. 5. Adamczyk E, Pralong V. (2017). “Na2Mn3O7: A suitable electrode material for Sodium ion batteries?” Chem. Mater., 29, 11, 4645. 6. Sada K, Senthilkumar B, Barpanda P. (2018). “Potassium-ion intercalation mechanism in layered Na2Mn3O7” ACS Appl. Energy Mater., 1, 10, 5410. 7. Sada K, Senthilkumar B, Barpanda P. (2018). Potassium Intercalation into Sodium Metal Oxide and Polyanionic Hosts: Few Case Studies, ECS Trans., 85, 13, 207.

Resume : Zinc Oxide (ZnO) has been under a great deal of attention for decades in the field of solar cells, semiconductor lasers, LIBs, and other devices. As an anode material for LIBs, ZnO has various advantages such as high theoretical capacity (987mAh/g), low cost, and good physical and chemical stability. However, its large volume change (over 228%) during cycling and intrinsic poor electronic conductivity would result in drastic capacity fading and poor cyclability. On the other hand, mixed oxides have been adopted as the anode materials to improve the electrochemical properties through the synergetic effects. Combining ZnO with other metal oxides would improve initial capacity and reduce degradation during cycling. Moreover, the electronic conductivity could increase by adding elements with good electronic conductivity. In this work, mesoporous MOx-ZnO (M = Mn, Co, Ni, and Cu) were synthesized by heating under reflux. The synthesized materials were analyzed by X-ray diffraction (XRD), nitrogen adsorption-desorption isotherms, and scanning electron microscopy (SEM). The materials were also investigated as anode material for LIB. They showed improved capacities than pure mesoporous ZnO. Among them, CoOx-ZnO exhibited much better reversible capacity, initial coulombic efficiency, and rate capability. This possibly arises from Co which helps to sustain the conversion reaction of ZnO.

Resume : Sodium-ion batteries (SIBs) are generating considerable interest for large-scale energy storage systems and electric vehicles. However, high energy density cathodes often show high power due to poor rate capability. The primary cause is large ionic radius of Na+ ion that provide high kinetic barrier to Na+−ion transport. The β−NaMnO2 show high discharge capacity but loses of long range ordering during sodium extraction that prevents it from fast charging. Here, we report successful aluminium doping of 4 and 11% to the parent structure to mitigate this problem. The β−NaMnO2 shows capacity retention of only 41% after 35 cycles when cycled at 1C−rate. On the contrary, aluminium doping of 4 and 11% shows capacity retention of about 76% and 80.4%, respectively after 50 cycles. The designed material, β−NaMn0.96Al0.04O2, can deliver a discharge capacity of 139 mAh g−1. These values demonstrate an excellent electrochemical reversibility at high rate. The density functional theory based analysis shows that aluminium doping increases bond length of Mn−O and a decrease bond length of Al−O. This increases the overall volume of the structure and facilitates free access to the sodium ions without significant distortion.

Resume : Lithium-ion batteries with high energy densities are required for batteries in IT devices and all-electric vehicles. Accordingly, silicon (Si) has received much attention as a promising anode material due to its excellent specific capacity (over 3000 mAh/g). However, it has suffered from poor cycle life because the huge volume change of the Si during repeated charge-discharge cycles results in particle pulverization and an unstable solid electrolyte interface (SEI). While various polymeric binders based on strong adhesion have improved the cycle life of Si nanoparticle anodes, they have yet to function properly, especially when the particle sizes are in the micrometer range with commercial levels of electrode loading. In fact, it is generally accepted that the binder is not solely capable of resolving such issues related with practical Si microparticle (SiMP) anodes. To solve these issues, we developed a novel polymeric binder in which 5% polyrotaxane (PR), consisting of polyethylene glycol (PEG) threads onto interlocked to a-cyclodextrin (a-CD) rings, is crosslinked with conventional polyacrylic acid (PAA) binder. The dual component binder, PR-PAA, imparts a high elasticity of 390% to the polymer network compared to 37% of bare PAA. Unlike previous binder networks that indicate ‘nonlinear softening’, the PR-PAA shows ‘nonlinear stiffening’, leading to its superior elasticity resulting from the a-CD ring sliding motion of mechanically interlocked PR. Although the PR-PAA was not able to prevent from pulverization of SiMP during cycling, it allows pulverized Si particles to remain coalesced without disintegration, maintaining a stable SEI layer. The PR-PAA binder enables robust cycling (91% retention after 150 cycles) even for SiMP electrodes (~ 2.1 ㎛) with a high level of areal capacity (2.67 mAh/cm), along with a high initial Coulombic efficiency of 91.22%. On the basis of this excellent cycling performance, a full-cell paired with LiNi0.8Co0.15Al0.05O2 (NCA) cathode was tested. While the full-cell exhibited an areal capacity of 2.88 mAh cm-2 within the range of commercial lithium ion batteries, it showed proper cycle performance such as 98% retention of the original capacity after 50 cycles. The introduction of a mechanical bond in the form of a PR can play a key role in addressing the chronic volume change issues of Si electrodes and therefore provides a general strategy to extend the cycle lives of high capacity lithium-ion battery electrodes.

Resume : Stabilized cubic Bi2O3 has known exhibits the highest ionic conductivity among the oxygen ion conductor, such as stabilized zirconia-based oxides and ceria-based oxides. Based on previous study, ionic conduction cubic doped Bi2O3 is highly dependent upon the content of Bi ions in the cation sublattice due to its characterisctic 6s2 lone-pair electronic configuration. Howerver, Bi2O3 containing more Bi (>80%) tends to transform to other structure than cubic fluoride. Based on thermodynamcis consideration, the increase in entropy is favorable for forming solid solution with lower free energy. In this study, the atomic fraction of Bi is increased from 75% to 88%. 25%Y2O3-doped Bi2O3 was used as the base-line material. For singly-doped Bi2O3, it has been observed that the cubic structure is not longer a stable structure when the cation sublattice contains Bi as high as 88%. In order to further enhance the conductivity of doped Bi2O3, it is necessary to increase the content of Bi ions without affecting its structural stability. Thus, the objective of this study is to investigate the structure stability of highly concentrated Bi2O3 with multiple dopants. The selection of dopants are based on the consideration of their valences, ionic radius, and defect reaction after doping into flourite Bi2O3. The crystal stucture of doped Bi2O3 will be examined using X-ray diffraction with Rietveld refinement. Electrochemical Impedance spectroscope (EIS) analysis of doped Bi2O3 will be evaluated. The corresponding microstructure will be observed using high-resolution SEM. The grain size and possible second phases will be carefully examined. The final results will be discussed and summarized in view of crystallization and defect consideration. Keywords : multi dopant Bi2O3, oxygen ion conductor, phase stability, high ionic conductivity

Resume : Metal oxides have attracted extensive attention as alternative lithium-ion anodes due to their high capacity combined with a high materials? true density and ease of handling, promising significant progress in energy density for future lithium-ion batteries. In recent studies, we have shown that the introduction of a transition metal (TM) dopant favors an enhanced cycling stability and rate capability, while moreover allowing for increased reversible capacities[1]. Herein, we present our in-depth investigation of the impact of the TM nature and content, choosing SnO2 as model compound[2][3]. The results obtained reveal that the incorporation of the TM dopant generally enhances the reversibility of both the alloying and conversion reaction, while the TM nature eventually governs the crystallite size, the long-term cycling stability, rate capability, and the average delithiation potential, which finally affects also the achievable energy density on the full-cell level. Following this research path, we have very recently extended this investigation to other metal oxides and discovered an even more remarkable effect. These results are anticipated to provide some general guidelines for the design of alternative metal oxide anodes, providing an enhanced performance compared to the state of the art. References [1] D. Bresser et al., Energy Environ. Sci. 2016, 9, 3348. [2] Y. Ma et al., Electrochimica Acta 2018, 277, 100. [3] Y. Ma et al., Sustainable Energy Fuels 2018, 2, 2601.

Resume : We attempt to demonstrate the experimentally supercapacitive performance of polyaniline (PANI) - cobalt hydroxide (Co(OH)2)-nickel hydroxide (Ni(OH)2) nanocomposites (NCs), prepared potentiometrically via electrochemical deposition, compared to phase pure individual nanostructures. Amorphous PANI, Co(OH)2 ? Ni(OH)2 and NCs are entirely different from one another from the surface appearance point of view, PANI exhibits nanofiber morphology, NCs exhibits nanofiber partially covered with Co(OH)2 - Ni(OH)2 materials and Co(OH)2 - Ni(OH)2 shows platelet morphology. The electrochemical properties of the PANI, Co(OH)2 - Ni(OH)2 and HNs electrodes have been investigated by cyclic voltammograms and galvanostatic charge-discharge. The specific capacitances of PANI, NCs, and Co(OH)2 ? Ni(OH)2 are found to be 0.59, 50, 46.4, 85.7, 74.1 and 312.5 F/g, respectively, at a sweep rate of 10 mV/s in 1.0 M NaOH electrolyte. The same nature of retention values in area of CV curves and power densities of PANI, NCs and Co(OH)2 ? Ni(OH)2 with increased in scan rates are 25.8, 70.5, 75.5, 76.6, 57 and 42.4%, respectively and the same nature of retention in charge density, specific capacitance, and energy density values are 38.7, 33.8, 40.7, 42.6, 23.1 and 17.3% respectively for PANI, NCs and Co(OH)2 - Ni(OH)2 electrodes with increase in scan rate.

Resume : Lithium ion capacitors (LICs) hold promise to bridge the gap existing between lithium ion batteries (LIBs) and supercapacitors (SCs), providing high energy density at high power densities, while keeping long cycle life. Traditionally, the goal has been pursued by means of a supercapacitor-to-LIC approach, replacing the capacitive negative electrode of a SC by a faradaic negative electrode. In this work, we focused on a battery-to-LIC approach, switching focus from hybridization to electrode engineering, enabling an ultrafast battery to perform in the LIC region. Thus, results shown are based on purely faradaic materials, but can mimic capacitive performance, allowing targeting high energy density at high power densities, while maintaining cycle life close to that of EDLCs.

Resume : Metal?organic frameworks (MOFs) are promising porous precursors for the construction of various functional materials for high-performance electrochemical energy storage and conversion. Herein we report several facile methods to rational design of novel nanoarrays on flexible carbon cloth substrate. One example is hollow NiCo2O4 nanoarrays obtained from a two-dimensional (2D) cobalt-based MOF, which is synthesized via a solution reaction with an additional annealing treatment. The as-obtained NiCo2O4 nanostructure arrays can provide rich reaction sites and short ion diffusion path. When evaluated as a flexible electrode material for supercapacitor, the as-fabricated NiCo2O4 nanowall electrode shows remarkable electrochemical performance with excellent rate capability and long cycle life. In addition, the hollow NiCo2O4 nanowall electrode exhibits promising electrocatalytic activity for oxygen evolution reaction (OER). Another example is hollow Co3O4 nanospheres embedded in nitrogen-doped carbon nanowall arrays on flexible carbon cloth (NC-Co3O4/CC). The hierarchical structure is facilely derived from a metal-organic framework (MOF) precursor. A carbon onion coating constrains the Kirkendall effect to promote the conversion of the Co nanoparticles into irregular hollow oxide nanospheres with a fine scale nanograin structure, which enables promising catalytic properties toward both OER and ORR. The integrated NC-Co3O4/CC can be used as an additive-free air-cathode for flexible all-solid-state zinc-air batteries, which presents high open circuit potential (1.44 V), high capacity (387.2 mAh g-1, based on the total mass of Zn and catalysts), excellent cycling stability and mechanical flexibility, significantly outperforming Pt and Ir-based zinc-air batteries. Our work provides good examples of rational design of hollow nanostructured arrays with high electrochemical performance and mechanical flexibility, holding great potential for future flexible multi-functional electronic devices.

Resume : As the theoretical limit of intercalation material-based lithium-ion batteries is approached, alternative chemistries based on conversion reactions are presently considered. The conversion of sulfur is particularly appealing as it is associated with a theoretical gravimetric energy density up to 2510 Wh kg?1 that is more than two times of the state-of-the-art lithium ion commercial cell. Unfortunately, the Sulfur conversion reaction is accompanied by 80% volume change and polysulfide shuttling[1]. The use of composite cathodes, incorporating carbonaceous materials and metal sulfides, can help improve cell performance by buffering volume changes while creating effective electron conduction pathways and enhancing sulfur utilization by catalytic effects[2]. Recently we studied the effect of different metal sulfides on the sulfur cathode and realized their beneficial effect towards improved electrochemical performance. The all-solid-state cell using a solid state Li2S-P2S5-LiI electrolyte, metal sulfides-containing composite cathodes based and Li metal showed stable cycling (200 cycles). The metal sulfide conversion mechanism is elucidated by different technics such as ex-situ XRD, SEM, and EIS. 1. Manthiram, A., et al., Rechargeable Lithium?Sulfur Batteries. Chemical Reviews, 2014. 114(23): p. 11751-11787. 2. Ulissi, U., et al., High Capacity All-Solid-State Lithium Batteries Enabled by Pyrite-Sulfur Composites. Advanced Energy Materials, 2018: p. 1801462.

Resume : The goal of this study was the development of advanced composite metal oxide-carbon nanotube (CNT) and metal oxide-graphene electrodes for supercapacitors with high active mass loading, high areal and gravimetric capacitances, good cyclic stability and low impedance. Chelating organic molecules with strong polydentate bonding to metal oxide surface were used as capping and dispersing agents. Advanced strategies for the dispersion of CNT and graphene were based on the use of commercial bile salts and organic dyes. Further advancements in the colloidal nanotechnology were achieved by the use of chelating polymers and complexes for the efficient colloidal processing of multicomponent systems. Various heterocoagulation techniques and liquid-liquid particle extraction methods were developed for the synthesis and design of nanocomposites. New colloidal strategies were used for the fabrication of advanced MnO2-CNT, Mn3O4-CNT, FeOOH-CNT composites for positive and negative electrodes of asymmetric supercapacitors.. The capacitance retention above 70% was achieved in the scan rate range of 2-100 mV s-1. Advanced supercapacitor electrodes were developed with areal capacitance as high as 9 F cm-2. The electrodes showed cyclic stability above 90% after 5000 cycles. New surface modification and synthesis technologies developed in this investigation allowed the fabrication of novel negative electrodes, which matched the capacitance of positive electrodes at active mass as high as 40 mg cm-2. As a result, we achieved significant improvement in capacitance of asymmetric devices. The composite electrodes were used for the fabrication of asymmetric devices with voltage window of 1.6V and high power-energy characteristics.

Resume : Li7La3Zr2O12 (LLZO) compound is considered as a very promising material for solid state electrolyte in lithium-ion batteries. This work describes the possibility of the formation of single phase cubic c-LLZO compound by ball milling of lithium carbonate, lanthanum hydroxide and zirconium oxide powder mixtures and their heat treatment. Influence of milling and annealing conditions was studied. XRD, TEM and DSC/TG experimental techniques allowed full characterization of the final milled and heat treated products.

Resume : Among various vanadium oxides, vanadium pentoxide (V2O5) has attracted attention for energy storage applications such as cathode materials for lithium-ion batteries and sodium-ion batteries, active materials for supercapacitors, and charge-injection-layer materials for field-effect transistors. Although there are many previous reports to fabricate the V2O5 thin films, atomic layer deposition (ALD) based deposition technique should be more intensively studied for achieving conformal and uniform V2O5 thin film because various energy storage applications have an arbitrarily defined structure. With this motivation, in this research, V2O5 thin films were successfully deposited by ALD using vanadium triisopropoxide (VTIP) as a vanadium source, and both H2O and O2-plasma as an oxidizing source, respectively. To clarify the structural and electrical characteristics of individual thin films, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Rutherford backscattering spectrometry (RBS) analyses were conducted. The analysis results confirmed that the formation of polycrystalline V2O5 thin film with high purity and compositional stoichiometry. To confirm the electrical characteristic of ALD-V2O5 thin film, the stainless steel substrate was adopted, and the stable electrochemical performances in Na-ion battery application was observed. More detailed fabrication processes and electrical performances will be introduced in the author?s presentation.

Resume : Energy concerns, related to the ever?increasing population and its growing energy needs, represent one of the highest society challenges. Lithium (Li)-ion batteries, thanks to their high energy and power density, low cost, long cycle time and no memory effect, are the most promising electrical energy storage devices. On the other hand, these batteries are composed by materials with high environmental impact and low degradability and, therefore, environmentally friendly components are needed. Silk based materials, derived from natural resources, have recently show their ability to act as Li-ion battery separators and electrode binders. Battery separators are an essential part of batteries, acting as physical barrier to prevent the sort circuit between cathode and anode. In this work, Li-batteries separators based on silk fibroin (SF) with controllable porosity have been developed by salt leaching technique, leading to excellent battery performance.

Resume : The miniaturisation of modern electronics along with the fast growth of autonomous wireless sensors, internet-of-things and wearable electronics, has stimulated the need for self-powered systems via energy harvesting from various ambient energy sources. Energy harvesting units usually require an energy-storage device to compensate for their power discontinuities and to ensure energy delivery over prolonged periods of time. In this work, we demonstrate the fabrication and integration of fully solution processed, co-planar NiO micro-supercapacitors through inkjet printing; thus, offering a path to readily scalable fabrication processes on large-area, flexible substrates at the fraction of the cost of traditional fabrication methods. Due to the high-capacity properties of NiO, the devices exhibit high areal capacitance of 75 mF·cm-2 per electrode and 13 mF·cm-2 as a whole device at 5 mV·s-1. The devices show ultra-high rate (up to 30 V·s-1) owning to the surfactant based saturated magnesium perchlorate gel electrolyte which is believed to form ion paths that facilitate in greater ion mobility. Importantly, we demonstrate that the inkjet-printed NiO thin film electrodes ? consolidated from nanoparticles containing non-ionic surfactant ? show over 10 orders of magnitude higher conductivity compared to single crystal NiO, which further enhances the charge transport pathways during charge-discharge cycles of the devices.

Resume : MXenes are recently discovered two-dimensional materials that have shown great promise for a number of applications, particularly for electrochemical energy storage. However, MXenes suffer from low capacities limited by the ion accessibility between layers due to small interlayer spacings in multistacked MXenes. Pillaring is a promising technique that has been used successfully to increase the interlayer spacing in clays, but has had limited application in MXenes up until now. We report a new amine-assisted pillaring methodology that intercalates silicon-based pillars between Ti3C2 layers. Using this technique, the interlayer spacing can be controlled with the choice of amine and calcination temperature up to a maximum of 3.2 nm, which is the largest interlayer spacing reported for an MXene. The pillaring process was characterised by a number of techniques, which give insight into how pillaring precursors interact with Ti3C2 surface groups, allowing the surface chemistry to be optimised for the process. The material was tested for Na-ion battery applications, and showed both increased capacity and remarkable stability compared with the non-pillared materials. These results show the promise of pillaring techniques in MXenes, and are expected to trigger further research in this area. Finely tuning and increasing the interlayer spacings in MXenes can be decisive for a range of applications, including energy storage, catalysis and gas separations.

Resume : The growing geopolitical and economical considerations forced the remergence of Na-ion technologies. The Na-ion based energy systems were proposed around the same time as Li-ion systems. Until recently, the former remained in the shadow of the latter as obtaining relevant single phase Na-ion based electrode materials remained a challenge. Now, the vast data base of material synthesis strategies has provided routes for the development of Na-ion based electrode materials. Two series of materials, which have become extremely prominent are based on sodium phosphates and vanadates. The results presented in the paper will show the electrochemical performance of NaMnPO4 nanostructures under ambient and non-ambient conditions like: temperature and magnetic field. It is well known that the electrochemical activity of the synthesised material is directly linked to the associated redox reactions. Use of redox additives to modify the electrolyte and ensuing specific capacitance in rarely investigated in Na-ion based energy storage systems. The present study clearly indicate that the performance of NaMnPO4 based supercapacitors can be increased by >1.5 times on the addition of redox additive [potassium ferricyanide]. This increase can be attributed to the synergistic contribution from the redox couples of the redox additive. The relevance of these results for many industrial applications will be presented.

Resume : This work explores a new class of material for Li-ion cathodes based on disordered rock salt structures, in particular the composition Li1.2Mn0.6Nb0.2O2 and the oxyfluoride version. These materials differ from the classical approach of layered oxides and allow for higher energy densities. This work is based on previous studies carried out by the G. Ceder?s group, and it aims to deepen the understanding of the material structure and electrochemical behaviour via an experimental approach. The first objective of this study is to synthesise various samples of disordered rock salt materials, for this the solid state synthesis is favoured. Materials are characterised using advanced microscopy and spectroscopy technics, especially a particular structure of local nano crystalline domains was observed by TEM despite the long range order observed using XRD. These structural observations are put in perspective with electrochemical performances. And then coating and doping strategies are set in place to discuss the importance of surface protection in the (electro)chemical stability of said material. A carbon coating is shown to improve electrochemical performances which can come from either surface protection or enhance electronic conductivity (or combination). In regards of oxygen stability which is one of the main structural issues in over lithiated materials, we investigate benefit from a fluoride doping through the synthesis using fluorinated transition metals type precursors.

Resume : In this work, we have investigated on the electrochemical properties and capacitive behavior of fabricated (CuO/Pt-TiO2) material with different copper concentration, using the cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and galvanostatic charge/discharge (GCD) measurements in 1 M Na2SO4 electrolyte solution, with three electrode assembly. The results have shown a high specific capacitance of 832 F.g-1 at a scan rate of 1 mV/s and 423 F.g-1 at a current density of 0.5 A.g-1. Moreover, we could get a good charge/discharge property with 93% stability even after 5000 cycles. These excellent results demonstrated that the CuO/Pt-TiO2 composite are promising for high-performance supercapacitors.

Resume : High-capacity cathode materials typically contain certain amount of Cobalt for stabilization and promoting their electrochemical properties. However, Co price has gone up significantly so high that Co-free cathode materials have been proposed and investigated recently. Co-free LiNi0.5Mn0.5O2 has received great attention due to its unique electrochemical properties. However, the discharge capacity and cycle stability of LiNi0.5Mn0.5O2 still need to be improved. Although several dopants such as Ga, Al, Mg, Ca have been added into LiNi0.5Mn0.5O2 to increase the stability of the structure and lower the amount of Li/Ni cation mixing. No conceivable explanation has been detailed reported. Thus, Mn ions will be substitutionally replaced with single or multiple dopants. Dopants selected will trivalent and/or pentavalent ions with consideration of proper ionic radius. Solid state reaction and soft chemistry methods will be used to process layered oxides. The crystal structure and cation mixing in the layered structure will be examined using Rietveld refinement. Cyclic Voltammetry (CV) and electrochemical Impedance spectroscope (EIS) analysis of layered cathodes will be investigated. The changes in the electrochemical properties according to higher structural stability, lower polarization and lower charge transfer resistance will be discussed in view of crystallization and defect consideration. Keywords : LiNi0.5Mn0.5O2, Sol-gel method, Nb doping, Lithium-ion batteries

Resume : The use of dopants such as silicon, tin, and, more recently, antimony in carbonaceous anodes is a promising area of research to increase the performance of lithium and sodium ion batteries [1-3]. The biggest obstacle to the progress of this technology is the stability of these inclusions in the carbon material during charging and discharging, most notably the volume change of the active material [4-8]. An electrode design was synthesized that consists of a carbon xerogel via a sol-gel process (CX), which acts as a support structure for a dopant, silicon nanoparticles (SiNPs), and provides electronic conductivity. Syntheses have been made using poly(sodium 4-styrenesulfonate) (PSS) as a coating or binder. These syntheses showed positive results on the cyclability of the CX/SiNPs composite. A 5-fold increase was observed in the number of charge/discharge cycles before the reversible capacity was less than 80% the initial capacity when compared with a composite with no coating and conventional binder. The gradual loss in capacity in the coated composite is still unknown, but may be due to the interplay between SEI formation and the volume expansion of the SiNPs. These problems are now being addressed by various techniques to improve the chemical and mechanical stability, and tailoring the microporosity and mesoporosity to reduce the irreversibly capacity loss and increase the accessibility to the dopant material. References: [1] W. Luo et al. Journal of Power Sources 304 (2016) 340?345 [2] B. Guo et al. Journal of Power Sources 177 (2008) 205?210 [3] RSC Advances, 2012, 2, 4311?431 [4] W.J. Zhang, J. Power Sources 196 (2011) 13?24 [5] H. Wu, Y. Cui, Nano Today 7 (2012) 414?429. [6] L.Y. Beaulieu, K.W. Eberman, R.L., et al. Electrochem. Solid-State Lett. 4 (2001) A137?A140. [7] J.H. Ryu, J.W. Kim, et al. Electrochem. Solid-State Lett. 7 (2004) A306?A309. [8] M.A. Rahman, G. Song, A.I. Bhatt, et al. Adv. Funct. Mater. 26 (2016) 647?678.

Resume : Classical potentials-based methods have been used to study the impact of fluorine doping on the solid Li electrolyte LLZO (Li7La3Zr2O12). Incorporation of fluorine into the LLZO structure was found to be most favourable on the oxygen site, with a charge compensating lithium ion vacancy being generated with a defect energy of 1.9 eV. The generation of lithium ion vacancies is also the usual compensating defect in cation doped LLZO, leading to stabilisation of the cubic phase at lower temperatures, indicating fluorine doping may have the same effect. Molecular dynamics simulations on both pure LLZO and ~4% F-doped LLZO indicate a stabilisation of the cubic phase at room temperature upon doping, whereas the pure LLZO system becomes cubic only above 700 K. The lithium diffusion properties of the systems were also studied and indicate a marked increase in lithium diffusion in the F-doped LLZO system below the usual phase transition temperature of pure LLZO, attributed to the stabilisation of the cubic phase. Above the phase transition temperature however the pure LLZO system shows higher lithium diffusion than the F-doped system, which we attribute to the trapping of lithium vacancies by the fluoride defects.

Resume : In operando analysis of Li-air batteries can lead to further comprehension about the electrochemical reaction mechanisms and the electrodes morphology changes over the cycles of charge and discharge. However, to achieve significant results, electrode surface texture and atmosphere conditions shall be rigorous controlled and, therefore, unique cell design must be developed. In this work, two different cells were designed for in situ and in operando analysis of Li-air batteries by synchrotron radiation X-ray diffractometry and AFM microscopy combined with synchrotron radiation nano-FTIR spectroscopy. The cells were 3D-printed in stainless steel by additive manufacturing by direct metal laser sintering. The charge and discharge process were performed in purified synthetic air chambers, with air humidity below 5%. For the X-ray analysis, work electrodes with 0.2 g.cm-2 of carbon nanotubes were used. The diffractograms indicated formation of detectable Li2O2 and Li2CO3 after 20h of discharge. For the AFM/nano-FTIR procedure, the electrode was polished until rugosity lower than 30 nm and a 50 nm gold layer was deposited by the electron-beam process. A 50 nm binder/Super P carbon layer was added by spin coating. The nano-FTIR was used to monitor the electrolyte decomposition that showed no changes after 5 full cycles. The combination of these two techniques can provide useful information about the performance of different types of electrodes and electrolytes in Li-air batteries.

Resume : Sodium ion batteries have been spotlighted as alternative to lithium ion batteries due to the abundance of sodium and similar reaction mechanism. Particularly, red P has attracted interest as an anode material due to low potential voltage and highest sodium storage capacity. However, low electronic conductivity and massive volume expansion during cycle life cause poor cyclability. In previous studies, transition metal phosphides, which has inactive metal matrix, have shown the potential to solve the cyclic problems. Especially, transition metal di-phosphides are promising candidates because of higher theoretical capacity than other metal-rich phosphides and do not involve severe volume expansion as red P. Among several di-phosphides, nickel di-phosphide (NiP2) has great advantages such as high theoretical capacity, low cost and high electronic conductivity of nickel matrix. We synthesized NiP2 phase via high energy mechanical milling and investigated electrochemical properties as an anode for sodium ion batteries. The NiP2 electrode delivered the discharge and charge capacities of 724 and 539 mAh g-1. To enhance the electrical contact and structural integrity, we synthesized NiP2/carbon nanocomposite by wet mechanical milling to homogeneously disperse the nano-scale carbon onto the micro-scale NiP2 particles. The NiP2/C electrode showed the high capacity retention (82.7% retention after 90 cycles), which demonstrates the high-performance anode material for sodium ion batteries.

Resume : High-capacity cathode materials typically contain certain amount of Cobalt for stabilization and promoting their electrochemical properties. However, Co price has gone up significantly so high that Co-free cathode materials have been proposed and investigated recently. Co-free LiNi0.5Mn0.5O2 has received great attention due to its unique electrochemical properties. However, the discharge capacity and cycle stability of LiNi0.5Mn0.5O2 still need to be improved. Although several dopants such as Ga, Al, Mg, Ca have been added into LiNi0.5Mn0.5O2 to increase the stability of the structure and lower the amount of Li/Ni cation mixing. No conceivable explanation has been detailed reported. Thus, Mn ions will be substitutionally replaced with single or multiple dopants. Dopants selected will trivalent and/or pentavalent ions with consideration of proper ionic radius. Solid state reaction and soft chemistry methods will be used to process layered oxides. The crystal structure and cation mixing in the layered structure will be examined using Rietveld refinement. Cyclic Voltammetry (CV) and electrochemical Impedance spectroscope (EIS) analysis of layered cathodes will be investigated. The changes in the electrochemical properties according to higher structural stability, lower polarization and lower charge transfer resistance will be discussed in view of crystallization and defect consideration. Keywords : LiNi0.5Mn0.5O2, Sol-gel method, Nb doping, Lithium-ion batteries

Resume : Li-air batteries can have theoretical specific energy of more than 9 times that of current Li-ion batteries. However, the applications of Li-air batteries is generally limited by the low cyclability. Oxygen reduction reactions at the cathode introduce reactive intermediates including superoxide, leading to battery materials degradation. Recently, the use of ionic liquids (ILs) in the electrolyte material for Li-air battery has shown promising cyclability and it is achieved by mixing an ionic liquid with dimethyl sulfoxide (DMSO) in the electrolyte. However, the local solvation and diffusion mechanisms of Li-ion in such an IL-molecular solvent mixture solution is not yet understood. In this research, DFT molecular dynamics simulations are employed to study the systems of Li-ion in mixture solutions of the IL 1-butyl-1-methylpyrrolidium bis(trifluoromethylsulfonyl)imide ([C4C1pry] [NTf2]) and DMSO with respect to different mixing ratios. The Li-ion local solvation structure and the diffusion mechanisms are studied. CP2K is used to perform the calculations. Mixed Gaussian and plane waves approach is employed with double-? valence plus polarization gaussian basis functions and 400 Ry energy cut-off plane-wave expansions. Goedecker-Teter-Hutter (GTH) pseudopotentials are used for all atoms. The Perdew-Burke-Ernzerhof (PBE) exchange-correlation functional is used. The research can benefit the design of future electrolyte systems of Li-air batteries by enhancing the understanding of the solvation of Li-ion in an IL-DMSO solution under atomic level.

Resume : High energy density electrode materials are highly desired in the area of energy storage to satisfy the demands of modern society's development. The porous natural of the hybrid carbon materials and its micro-scale porous distribution is attractive in energy storage fields. Conjugated microporous polymer (CMP) was synthesized through coupling polymerization with the catalysis of noble metal. The porous width of CMP can be adjusted by different precursors, while the noble metal catalyst will remain in the porous CMP after polymerization. After pyrolysis of the CMP, the noble metal nanoparticles will be encapsulated in the carbon matrix. The noble metal nanoparticles encapsulated in carbon materials will show its synergistic effects in energy storage area and potential applications in other fields. Pd Encapsulated porous carbon materials (Pd-PCMs) were prepared from the coupling polymerization of aryl halide and aryl terminal acetylene, whereas Pd(PPh3)4 serves as both the catalyst in polymerization and the precursor of Pd encapsulated in Pd-PCMs. With its porous microstructure and encapsulated Pd nanoparticles among porous carbon materials, Pd-PCMs provide strong physical confinement and surface chemical interaction to improve the affinity of polysulfides to the carbon matrix. The capacity of the battery is 920 mAh/g after 200 cycles at rate of 0.3C. The application of Pd-PCMs in Li-S batteries has broadened the applications of CMP and its derivatives in the field of energy storage, and with different particles encapsulated in adjustable porous carbon materials, CMP and its derivatives will also show its potential applications in other fields like catalysis and environmental applications.

Resume : Energy storage performances of Ni-based electrodes rely mainly on the peculiar nanomaterial design. In this work, a novel and low-cost approach to fabricate a promising core-shell battery-like electrode is presented [1]. Ni(OH)2@Ni core-shell nanochains were obtained by an electrochemical oxidation of a 3D nanoporous Ni film grown by chemical bath deposition and thermal annealing. This innovative nanostructure demonstrated remarkable charge storage ability in terms of capacity (237 mAh g-1 at 1 A g-1) and rate capability (76% at 16 A g-1, 32% at 64 A g-1). The relationships between electrochemical properties and core-shell architecture were investigated and modelled. The high-conductivity Ni core provides low electrode resistance and excellent electron transport from Ni(OH)2 shell to the current collector, resulting in improved capacity and rate capability. The reported preparation method and unique electrochemical behaviour of Ni(OH)2@Ni core-shell nanochains show potential in many field, including hybrid supercapacitors, batteries, electrochemical (bio)sensing, gas sensing and photocatalysis. [1] M. Urso et al. Submitted.

Resume : With Na-ion batteries being considered as the future energy storage devices for stationary applications, significant effort is being made to establish stable electrodes. The present talk will focus on TiS2 cathodes and how to increase their cycle life. It will be shown that the electrolyte significantly affects the cell performance, with NaFP6 in EC/EMC allowing for the most promising electrochemical properties recorded in the literature, namely a reversible capacity of 203 mAh g-1 at 0.2 C and 88 mAh g-1 at 10 C with a capacity retention of 92% over 50 cycles. Despite this promising performance the capacity still decayed during long term cycling. In-situ x-ray diffraction and high-resolution transmission electron microscopy imaging revealed that TiS2 underwent a large expansion of 17.7% along the c direction and irreversible phase transformations took place during the sodiation/de-sodiation process, which lead to severe mechanical strains and intragranular cracks. In comparison, the mechanical stability of TiS2 in Li-ion cells is significantly higher. The experimental results are interpreted with a mechanics model which revealed that the stresses present at the interface between the ion-intercalated TiS2 and pristine TiS2 is two times higher during sodiation than lithiation indicating that the electrode is more susceptible to failure/fracture during sodiation.

Resume : In this work, the trivalent transition-metal carbodiimide Cr2(NCN)3, crystallographically very similar to Cr2O3, is tested as a negative electrode material in Li-ion batteries showing excellent performance: in fact, it exhibits a reversible capacity around 700 mAhg?1 after 800 cycles, remarkably higher than those reported in the literature for divalent carbodiimides[1] and the analogue phase Cr2O3[2,3]. The origin of the extra capacity of Cr2(NCN)3 is discussed in terms of reversible electrolyte redox contribution. A detailed study of the electrochemical mechanism of this material was performed by several complementary operando and ex situ techniques. Operando X-ray diffraction confirms the activity of the material vs. lithium, but is insufficient to explain the whole mechanism due to massive amorphisation during lithiation. Operando Cr K-edge X-ray absorption spectroscopy (XAS), sensitive to short-range order around the Cr ions, was thus used to follow the reaction mechanisms. Operando and ex situ XAS analyses suggest a two-step conversion process implying two redox couples (Cr3+/Cr2+ and Cr2+/Cr0), with the formation of Cr metal nanoparticles at the end of the first lithiation. These promising results of chromium carbodiimide may open up a new approach for seeking transition-metal carbodiimide electrodes for future lithium-ion and sodium-ion batteries of high energy, high power, and long life span. References: [1] M. T. Sougrati, A. Darwiche, X. Liu, A. Mahmoud, R. P. Hermann, S. Jouen, L. Monconduit, R. Dronskowski, L. Stievano, Angew. Chemie - Int. Ed. 2016, 55, 5090?5095. [2] Z. Cao, M. Qin, B. Jia, L. Zhang, Q. Wan, M. Wang, A. A. Volinsky, X. Qu, Electrochim. Acta 2014, 139, 76?81. [3] Y. Zhao, J. Wang, C. Ma, Y. Li, Chem. Phys. Lett. 2018, 704, 31?36.

Resume : Narrow cell voltages of aqueous pseudocapacitive energy storage devices (1.0 ? 1.4 V), limits their use in the applications were volumetric energy density is a key issue. We tackle this issue by designing water-in-salt electrolyte based pseudocapacitive energy storage device. Use of water-in-salt solution as an electrolyte media, shifts the kinetics of water splitting reactions, allowing our pseudocapacitive cell to be operated in a voltage window (2.2 V) close to that of organic electrolyte-based supercapacitors. Our pseudocapacitive cell shows excellent rate capability (~48 %, between 8 and 80 C) and high stability (~92%) throughout 10,000 charge-discharge cycles (at 1 A g-1) and 25 h Voltage-Hold at 2.2 V. Remarkably, these results are competitive when compared with the performance of known asymmetric supercapacitors composed of fluorinated-imide based water-in-salt electrolytes. Moreover, our pseudocapacitive cell shows slower self-discharge and lower cell volume than activated carbon-based supercapacitors. Through this talk, we will disclose the strategies which we followed to design our pseudocapacitive cell and demonstrates our findings which support the reason behind the remarkable electrochemical performances. The implementation of our strategies will allow the community in building better energy storage devices based on pseudocapacitive charge storage.

Resume : Sodium-ion batteries have been proposed as a cost-effective alternative to the conventional lithium-ion batteries due to the abundant and cheap sodium resources. However, it is crucial to develop materials with high sodiation capacities and calendar life for high energy density sodium-ion batteries necessary for practical applications. In this regard, antimony-based alloying anodes offer high gravimetric and volumetric sodiation capacities but suffer from poor cycling stability. Herein, we employed high-throughput and industrially viable rapid-solidification technique to synthesize Fe-Sb alloy ribbons and investigated the electrochemical performance in sodium-ion batteries. The Fe-Sb alloy ribbons delivered ~466 mAh g-1 sodiation capacity at a specific current of 50 mA g-1 and retained 95% capacity after 80 cycles. The sodiation/desodiation mechanism was explored via cyclic voltammetry and ex situ X-ray diffraction studies. Moreover, the practical feasibility of the alloy anode was investigated in a full-cell configuration and delivered ~300 mAh g-1 (based on anode mass) at 50 mA g-1 with over 99% Coulombic efficiency. The study offers insights into the engineering of the active materials to promote efficient sodiation pathways to achieve enhanced cycling stability for practical applications.

Resume : Supercapacitors are promising energy storage devices due to the high power delivered, fast charge/discharge and long cycling stability. Nevertheless, the low energy density stored (~5Wh/kg) calls for future research on the development of new electrode materials. In this work, we show a facile procedure for the preparation of phosphate-functionalized carbonaceous graphene-based composites. The synthesis involves the condensation of a thin layer of phenolic resin on the surface of graphene oxide (GO) sheets using phosphoric acid as polymerization catalyst and functionalization agent. Afterwards, the resulting composite is pyrolyzed yielding highly homogeneous lamellar-shaped porous carbon-graphene composites combining two highly desirable features in supercapacitor electrodes; enhanced molecular diffusion and high electronic transfer. For sake of comparison, the graphene-free sample and the KOH-activated composite were also prepared to full understanding the role of graphene sheets and the porous properties on the supercapacitor performance. These materials were evaluated as electrodes for supercapacitors using different electrolytes. It was found that the presence of GO significantly improve the specific capacitance compared to the graphene-free sample. As well, phosphate-functionalization allows widening the operating cell potential window up to 1.3V, which increases considerably the energy density of the cell. To sum up, graphene-based and activated graphene-based composites provide excellent capacitance retention, energy and power densities and cycling stability.

Resume : Niobium oxides constitute a group of materials that has proved their versatility for different applications. Among them, one of the most promising is the use in supercapacitors, due to the high dielectric constant. Other interesting properties like a bandgap in the near UV range or a high refractive index make then interesting for photocatalysis or light guiding. However, it has been shown that the properties of the niobium oxides are highly dependent on the stoichiometry and crystal structure of the compound. Another important problem in our society is the huge amount of waste that humans generate. In this sense, one of the EU's priorities is to promote the transition to a circular economy, where the materials and products manufactured with them are kept in the life cycle as long as possible. In this work, the starting niobium pentoxide (Nb2O5) is obtained from the tailings from the Penouta Sn?Ta?Nb deposit. The first step has been the characterization of the properties of the recycled products, and compare its properties with a commercial one, showing the good quality of the obtained material. Using the recovered Nb2O5 as precursor, microrods have been grown using a vapor-solid method. The obtained microstructures have been characterized by means of X-ray diffraction, scanning electron microscopy, luminescence and Raman spectroscopy. The structural properties of the treated material have been studied in detail to elucidate its application in supercapacitors.

Resume : In this work, nanosized Sn rich Sn-SnSb alloy nanopowder is prepared via microwave-assisted hydrothermal route. Ex-situ XRD studies are conducted to investigate the reversible sodiation/desodiation behaviour of the Sn-SnSb nanopowder. Rietveld refinement of the XRD patterns indicates a multi-step sodiation process. Primary sodiation of SnSb phase starts with the selective sodiation of Sb forming Na3Sb. Subsequently, Sn sodiates in a series of steps which involves the formation of intermediate phase regions, comprising of amorphous and crystalline domains. In a general scheme of things, Sn first sodiates to form NaSn. Further sodiation results in the formation of Na9Sn4 and upon complete sodiation, a highly crystalline Na15Sn4 phase forms. Finally, to achieve the high-rate performance, Sn-SnSb nanopowders are sandwiched between NrGO nanosheets and impregnated into electrodeposited microporous Ni foam current collector. This electrode with 40 wt% NrGO content delivers a stable reversible capacity of 580 mAhg-1 at 0.1 Ag-1 retained for 100 cycles, a high-rate capacity of 200 mAhg-1 at 4 Ag-1 and 400 mAhg-1 capacity retention when cycled at a constant high rate of 1 Ag-1 for 150 cycles. The nanocomposite shows 93% capacity recovery after extensive rate capability studies in conjunction with cyclability studies for 150 cycles. This remarkable rate performance is a consequence of this novel electrode architecture which effectively tackles the volumetric fluctuation during high kinetic sodiation/desodiation processes.

Resume : In this contribution we realized correlated nanoscale-resolved studies of the structural and functional transformations in LiMn2O4 (LMO) cathodes during lithiation and degradation via scanning probe microscopy (SPM) and confocal Raman microscopy (CRM). SPM measurements showed that Li ions are distributed non-uniformly inside LMO particles while average diffusion coefficient in individual particles had a value close to the expected one for fully charged LMO. Enhancement of the concentration in vicinity of particle boundaries was attributed to the limited diffusion path of lithium forming an apparent core?shell structure. We registered also about 50% decrease of the diffusion coefficient at thin interface layer of the individuals LMO particles (from a few to tens nanometers). Complementary structural study by ?RM showed that battery cycling leads to: (1) formation of Mn3O4 phase with its further dissolution in the electrolyte; (2) qualitative change of the lithiation process in cycled LMO cathodes with formation of the significant inhomogeneous lithiation state. The segregation of Mn3O4 phase was found as well in vicinity of the particle boundaries and thereby determine diminished electrochemical activity. On contrary, Mn3O4 phase was not revealed in aged cathodes, which prove that the dissolution of this phase occurs mostly at the beginning of cycling while further mechanism of capacitance fade is due to inhomogeneity of the delithiation process [2]. The work was financially supported by the Portuguese Foundation for Science and Technology (FCT) within the project PTDC/CTM-ENE/6341/2014. This work was developed within the scope of the project CICECO-Av. Inst. of Mat., FCT Ref. UID/CTM/50011/2019, financed by national funds through the FCT/MCTES. The ESM and CRM measurements were done in Ural Federal University. This part of research was made possible by Russian Science Foundation (Grant 17-72-10144).

Resume : With the growing understanding pertaining to the materials used in battery and supercapacitor technologies, the recent trends indicate industrial need for an energy storage device, which simultaneously has characteristics of both batteries and supercapacitors. Such hybrid storage devices have been termed as ?superbats.? On going through the literature, it is obvious that many few magnetic transition metal oxides that have been employed as active materials in Li-batteries and supercapacitors. The synthesis protocol for obtaining simple oxides of Fe, Ni, Co, Cu and Mn with morphologies ranging from solid to hollow has been established. A question, which has remained ignored in the field of supercapacitors is: will the device performance be affected near a magnetic field, if it is fabricated using nanostructured electrode materials that are also magnetic? Based on our recent studies on supercapacitors utilizing novel nanostructured metal oxides of Fe, Co, Mn, and Ni, it will shown that the answer is: yes, it will get affected! In actual terms, the change in specific energy is quite appreciable, with the highest change of ~ 170% observed in Fe2O3 based supercapacitors, when the magnetic field varies from 0 to 5 mT. We will also show that the magnetic field dependent variation in energy storage devices is quite complicated. It is also dependent on the nature of electrolyte ions used in the electrochemical device. This can be explained in terms of the Lorentz force induced motion, which will depend on the mass of the ion. The lighter ions will be able to travel further inside the electrode bulk due to higher kinetic energy. Therefore, higher specific capacitance values will be obtained.

Resume : Lithium-ion batteries based on intercalation compounds have dominated commercial markets, in which LiCoO2, LiMn2O4, and LiFePO4 be used as cathode materials. These positive materials with lithium-conducting crystals can present the outstanding cyclic stability, while the capacity limites by less than 1 Li+ transportation during per redox site. Moreover, conversion cathodes, such as FeF2, FeF3, or FeS2 et al., had been reported the electrochemical behavior with multi-electrons transportation, when the high-valent transition metals was reduced to the metals. However, the sluggish kinetics, large overpotentials and absence of build-in Li sources hinder its application in commercial batteries. Recently, the new concept of lithium-free transition metal monoxides for positive electrodes based on interfacila mass storage, has been developed via blending with nanosized lithium fluoride and metal monoxides, which shifted negative materials to positive materials (average voltage of over 3V) by surface oxidation to form M-O-F compounds. The size effect and spatial distribution were the crital factors for delivering high capacity performance at room temperature. However, establishing nanostructures is still a challenge by a mechanical milling. In this work, we prepared LiF-NiFe2O4 nanocomposite thin film by PLD method. The cyclability of LiF/NiFe2O4 thin films without any additions was regarded as ideal model electrode, which are bene?cial to discovery and veri?cation of the intrinsic electrochemical characteristics. The LiF and NiFe2O4 in molar ratio of 4:1 composite thin film is able to achieve large capacity of 235 mAh g?1 after the reconversion reaction upon the first charge. The capacity from the surface-controlled reaction accounts for 91% of the overall capacity with a cycle life stable over 100 cycles.

Resume : In the preparation of carbon-based supercapacitors, the doping of heteroatoms is an effective way to improve the specific capacitance. In this paper, we prepared a biomass carbon electrode with a considerable nitrogen content of 10.82%. In the N-doped biomass carbon materials, pyridine nitrogen and pyrrole nitrogen were the main forms of nitrogen, and the sp3 hybrid nitrogen greatly increased the specific capacitance. Among the precursors of biomass in this study, fungal hypha (FH) enabled the best electrochemical performance of carbon electrode with a specific capacitance of up to 279 F/g and a specific capacitance of 68.1% (190 F/g) at a high current density of 20 A/g. In addition, the sample has an excellent anti-radiation capability with specific electrical capacity of 227 F/g at 1 A/g after irradiated by ? ray (50 kGy). This universal and cost-friendly method obviously expanded the specific surface area of biomass materials, increased the amount of nitrogen doping biomass carbon materials. Key words?supercapacitor, biomass, fungal hypha, nitrogen doping, ammonia

Resume : The lithium oxygen batteries have received wide attention as an enabling technology for a mass market entry of electric vehicles due to a potential capacity much higher than current Li-ion technology. Carbon has been used widely as the basis of porous cathodes for nonaqueous Li?O2 cells, produce Li2O2 as the main product that electrically insulative and would passivate the cathode, cause very high charge-discharge overpotential which will make kinetics of oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) more sluggish, then compromise the capacity and cycle life. Therefore, seeking effective electrocatalyst to reduce the overpotential is crucial to enhance the performance of lithium oxygen batteries. Perovskite oxides have been regarded as the most promising materials due to high electrical conductivity and high electrocatalytic activity for the ORR and OER activity. Ba0.5Sr0.5Co0.8Fe0.2O that exhibit defective structures for oxygen vacancy, excellent oxygen anion mobility and exchange kinetics make it excellent candidate as cathode electrocatalyst. Herein, perovskite Ba0.5Sr0.5Co0.8Fe0.2O use as cathode catalyst can increase the discharge capacity from 5565 mAh/g into 13558 mAh/g at 0.05 mA/cm2 and improve cycle stability from 16 cycle to 26 cycle at 0.1 mA/cm2 with limited capacity 1000 mAh/g.

Resume : With the increasing demand of energy market and application fields overwhelmed all aspects of the society such as grid-level energy storage, transportation, the military industry and the space industry, advanced energy storage devices have been urgently required and widely studied. [1] Lithium-ion batteries (LIBs) have attracted many attentions because of their outstanding advantages such as high energy density, long cycle life, and environmental benignity. To further improve the energy density of the LIBs, novel anode materials (such as metal oxides or lithium metal) and cathode materials (such as sulfur) have been invited to replace the conventional graphite anode and lithium metal oxides cathode, respectively. [2] TiO2 has received considerable attention owing to its non-toxicity, natural abundance, stable solid electrode interface (SEI) and controllable structure, and was employed as anodes, host or support materials and passivation layers for LIBs. [3-5] Herein, we developed several strategies for building novel electrodes with nano-structured TiO2 material to enhance the lithium storage property as well as battery performance of LIBs. For instance, a kind of carbon coated TiO2 aerogels are synthesized and composed of small anatase TiO2 nanocrystals (?5 nm) coated by conformal ultrathin carbon coatings. It shows high specific surface area ?235.7 m2 g-1 and average pore size ?11 nm. As anode material for lithium-ion batteries (LIBs), the carbon coated TiO2 aerogels exhibited a superior high rate performance and deliver a capacity of 133 mAh g-1 after 3000 cycles at 10 C. [6] In addition, we designed and prepared TiO2 nanofilms-coated graphene-metal oxide anodes, which exhibit exceptional electrochemical performance, especially great cycling stability. In such integrated anode, amorphous TiO2 nanofilms can prevent the pulverization, expansion and detachment of metal oxide nanoparticles on graphene, and increase the flexibility and mechanical strength of graphene hybrid anodes. [7] Moreover, a novel sulfur host composed of TiO2 nanofilm interfaces coating on mesoporous carbon is designed and shows high surface area, considerable electrolyte wetting capability and strong absorption for lithium polysulfides. Owe to the pivotal role of TiO2 interfaces on the surface of 3D interconnect conductive carbon matrix, the sulfur cathode exhibits a high initial specific capacity of 1455 mAh?g-1 and maintained 1242 mAh?g-1 after 200 cycles at 0.1 C (1C = 1675 mAh?g-1) current density, and also delivers excellent long term cycling performance at 1 C with initial capacity of 720 mAh?g-1 and capacity remained up to 81% after 1000 cycles. In conclusion, these nano-structured TiO2 utilization strategy for functional electrodes are hopefully employed in the next generation lithium secondary batteries or other energy storage devices. References 1. P. G. Bruce, S. A. Freunberger, L. J. Hardwick, J.-M. Tarascon, Nat. Mater. 2012, 11, 19. 2. J.B. Goodenough, K.-S. Park, J. Am. Chem. Soc. 2013, 135, 1167. 3. S. Goriparti, E. Miele, F. De Angelis, E. Di Fabrizio, R. Proietti Zaccaria, C. Capiglia, J. Power Sources 2014, 257, 421. 4. J. Zhang, H. Huang, J. Bae, S.-H. Chung, W. Zhang, A. Manthiram, G. Yu, Small Methods 2018, 2, 1700279. 5. X. Cheng, Y. Li, L. Sang, J. Ma, H. Shi, X. Liu, J. Lu, Y. Zhang, Electrochim. Acta 2018, 269, 241. 6. C. Zhang, S. Liu, Y. Qi, F. Cui, X. Yang, Chem. Eng. J. 2018, 351, 825. 7. S. Liu, W. Yue, C. Zhang, D. Du, X. Yang, J. Alloy Compd. 2018, 769, 293.

Resume : Alkaline-rich transition metal oxydes are candidates as sodium ion batteries positive electrode materials. P2-structures provide capacities in the 90-100 mAh/g range, a working potential close to 3.5V (vs. Na/Na+) and a suitable rate capability[1]. In this communication, we will present several materials synthesiwed in the Li-Na-Ni-Mn-Fe-O system, where cheap iron(III) ions can replace nickel(II) in a P2-[Li,Ni]1,02[Ni,Mn]0,85O2 structure. Doping influence on the compounds structure and morphology will be studied by spectroscopy (Mössbauer, Raman, EIS), X-rays diffraction and electronic microscopies. Electrochemical properties are also affected by the iron doping and will be evaluated by galvanostatic and voltammetric techniques. [1] M. D. Slater, D. Kim, E. Lee, C. S. Johnson, Sodium-ion batteries, Advanced Functional Materials 23 (8) (2013) 947-958.

Resume : Lithium-ion type energy storage is the most popular energy storage method, but now is a time when significant improvement is needed. Major attempts have been made to improve the components that makeup energy storage devices such as lithium-ion batteries (LIBs) and capacitors (LICs), the most promising of which is the anode part. Nanocrystalline metals are promising building units to realize high-capacity replacing graphite in lithium-ion type energy storage, but several disadvantages that occur during repetitive reactions must be remedied. Another challenge is the lack of a fast and scalable process to possibly fabricate nanocrystalline metals into real electrodes. Herein, we report polymer-triggered synthesis process to generate graphene pliable pockets (GPPs) can remedying the limitations of nanocrystalline metals for high-performance LIBs and LICs. Also, we introduce Metal_encapsulated GPPs (M_GPPs) that can be fabricated via the ultrafast dynamic treatment of polymers and graphene on the surface of nanocrystalline metals. This process is also shown to enable scalable mass production upon increasing the batch size. The method we use is very different from the traditional way of coating nano metal materials with carbon precursors. We simply mix the graphene and metal nanoparticles in solution, then add the polymer and mix them well. At this time, we have learned how to accurately control the molecular weight of the polymer, and that is a crucial role in the formation of M_GPPs. We remove the polymer through low-temperature heat treatment (< 450 ?), and then we can get the M_GPPs structure we want. We have tested the obtained M_GPP under various conditions as the anode of LIBs and LICs, and we have found that this technology can be applied to the industry right away. We believe that our M_GPPs structure can be used as an additive in the current market and we would like to report it.

Resume : With the bloom of portable and wearable electronics, electrochemical storage devices featured with high performance, low cost, environmentally-friendly, light weight, thin and flexible natures come more essential than ever. In this work the potential of employing electrophoretic deposition (EPD) for fabricating Li-ion battery electrodes without using binders and in particular eliminating volatile and toxic organic solvents such as n-methyl 2-pyrrolidone (NMP) is implicated. Bismuth iron oxide (BiFeO3; BFO) is regarded as an alternative anode material for lithium ion batteries (LIBs) due to its high theoretical capacity (770 mAh g?1) natural abundance, and low cost. However, the poor cyclic performance resulting from the low conductivity and huge volume change during cycling impedes its application. Here we report a facile electrophoretic deposition route to fabricate the BFO/GO (graphene oxide) electrode, simultaneously achieving material synthesis and electrode assembling. The main benefit of electrophoretic deposition to fabricate the electrode resulting as a significant improvement of the electrochemical properties , even without binders, the adhesion and mechanical firmness of the electrode are strong enough to be used for LIB anode. The fabricated BFO/GO electrode exhibits a stable reversible specific capacity of 710 mAh g?1 at a specific current density of 0.2 A g?1 which is maintained for 100 cycles, shows much improved electrochemical performance in terms of excellent cyclability and rate capability. Hence EPD serves as a simple, economical technique to fabricate flexible negative electrode coating for green Li-ion battery fabrication alternative. KEYWORDS: bismuth ferrite, graphene oxide, lithium ion battery, anode, electrophoretic deposition

Resume : The development of supercapacitors featured with high charge-discharge rate, high energy density and excellent cycling ability is getting more and more popular nowadays. However, several problems of conventional activated porous carbon structure exist, such as unconnected pathway for electrolyte, poor mechanical property due to discontinuous framework, and trade-off between energy density and power density. Therefore, it is still challenging to meet the requirements of a novel electrode structure with good flexibility, high capacity and long cycling lifetimes at the same time. Inverse opals (IOs) compared to other porous carbon aerogel structures, offered not only theoretically the highest specific surface areas but also a continuous porosity structure. In this work, silk fibroin (SF) doped with conducting polymer monomer (3,4-ethylenedioxythiophene) (PEDOT) were backfilled into the colloidal photo crystal template of polystyrene (PS) beads via a one-step electrogelation/electropolymerization. After carbonization process, a newly-design carbonized-polymer IOs electrode is prepared. The continuous IO with macro porosity provided short diffusion length for electrolyte and an open structure for better mechanical stability. Moreover, micro/mesopores embedded in the carbonized silk fibroin protein backbone boosted the specific capacitance. Besides, heteroatoms existing in the SF like N and faradic capacitance by PEDOT provide extra specific capacitance. Note that the non-conductive SF is transformed into pseudographitic pyroprotein by carbonization over 350?, which increased the capacitance. EDX/XPS proved the polymerization of SF-PEDOT composite, and RAMAN demonstrated the existence of graphene-like microstructure by D/G band depending on the carbonization temperature. The carbonized SF-PEDOT IOs demonstrated excellent mechanical property and stability (10000 cycles), as well as showing a high capacitance of 250 F g-1. To sum up, the homemade porous carbon IOs electrode holds promise as flexible supercapacitor for biomedical application or wearable devices.

Resume : Flexible lithium-ion batteries with a wide range of form factors have garnered considerable attention as a promising power source for versatile-shaped electronic devices such as roll-up displays, wearable electronics, and biomedical devices. Therefore, development of flexible Li-ion batteries with non-liquid electrolyte is highly desirable. The present study is aimed to develop flexible, bendable gel polymer electrolyte (GPE) with improved ionic conductivity for safe lithium-ion batteries to power flat flexible devices. For this purpose, several aliphatic structured polymers are chosen in order to prepare GPE. Polyacrylonitrile nanofiber, obtained by electrospinning, incorporates GPE as a compliant skeleton and improves its mechanical properties. The polymer electrolyte matrix is prepared directly inside the polymer nanofiber skeleton by UV-crosslinking of acrylate monomers in presence of lithium salts. By this method, a series of GPE were easily obtained by changing monomer types, Li salt, and nanofiber material. The optimal composition of GPE with the best electrochemical performance was investigated with the flexible cathode. Acknowledgements This research was supported by the Faculty-development competitive research grant ?Development of safe and high performance flexible Li-ion batteries? from Nazarbayev University for 2019-2021.

Resume : The demand and supply for energy should go synchronised for the modern world of science and technology. The renewable production of energy is not substantial until it is able to meet people need at suitable time. The electrochemically active materials have ability to store the charge in the wide potential region with high Coulombic efficiency. But these come with lot of issues like low electronic conductivity, fading of capacity and less output of energy and power density. Thus, there is always underperformance of conventional energy storage devices (batteries and supercapacitors) which relied upon the electrochemistry. To address these shortfalls, let us think in a different way and apply physiochemical route to storage charge. Subsequently, the magnetic effect on the metal oxides can be investigated fabricating low cost, eco-friendly and potential electrode materials for energy storage devices. In this work, we report a facile and economic approach to produce magnetic electrode materials like Ni/NiO and Fe2O3 with an aim to achieve an improved electrochemical activity and output high performance device. The present synthesis strategy demonstrates pinch method followed by air annealing at 500 ? for synthesizing the metal oxides. The crystallinity of products was confirmed by XRD, Raman and FT-IR spectroscopy analysis. The FE-SEM reveals the morphology of metal oxides. The electrochemical performances of Ni/NiO and Fe2O3 were investigated by cyclic voltammetric, charge-discharge and electrochemical impedance spectroscopy studies in a three electrode set-up, in both on-off magnetic fields. Interestingly, it was found that the degree of redox reactions in the synthesised materials varies up to a high extent in presence of magnetic field. Further the hydro-magnetoresistance for both the electrode materials was investigated and discovered that the charge storage capacity hiked due to decrease in hydro-magneto resistance. This ultimately improves the electron mobility. To realise the practical applicability, solid-state prototype device was fabricated using Ni/NiO as positive and Fe2O3 as negative electrode sandwich with gel-electrolyte. The energy density and power density of prototype device was demonstrated on-off magnetic influence. The physio-electrochemical investigations on the fabricated device revealed that the prototype-device exhibited a high energy and powder density. Thus, in the present work we have revealed a cheap and effective scheme to serve as precedent to develop potential electrode materials for energy storage devices. References: 1. A. Molinari, P. M. Leufke, C. Reitz, S. Dasgupta, R. Witte, R. Kruk, H. Hahn, Nat. Commun., 2017, 8, 15339-15348. 2. H. T. Das, K. Mahendraprabhu, T. Maiyalagan, P. Elumalai, Sci. Rep., 2017, 7, 1-14. 3. S. Pal, S. Majumder, S. Dutta, S. Banerjee, B. Satpati, S. De, J. Phys. D: Appl. Phys., 2018, 51, 375501-375510. 4. E. Duraisamy, H.T Das, A. S. Sharma, P. Elumalai, New J. Chem., 2018, 42, 6114-6124. 5. M. Ristic, Y. Gryska, J. V. M. McGinley, V. Yu?t, IEEE Trans., 2014, 61, 4225-4264. 6. F. Torrisi, T. Carey, Nano Today, 2018, 23, 73-96.

Resume : Despite the commercial success of Li-ion batteries (LIB), substantial improvements are still necessary in terms of energy density enhancement and cost reduction, especially for the emerging fully-electric vehicle market. One promising route is to use alloying and conversion negative electrodes due to their high theoretical capacity, which would increase overall battery?s energy density. The main challenge with this type of materials is the volume change upon cycling and the breakage of the SEI, which results in a continuous reduction of the electrolyte at the electrode surface, leading to a thickening of SEI as well as disintegration of electrically conductive network by the formation of insulating decomposition products in-between the electrode constituents. One way to improve the cycling stability of high-specific-charge negative electrodes is by using electrolyte additives, where one of the most investigated is FEC, as it has been shown that a thinner, flexible and homogeneous FEC-based SEI leads to a significant performance enhancement of the negative LIB electrodes. Here, we present a detailed morphological and chemical study of graphite and SnO2-graphite electrodes cycled in FEC-containing electrolytes, where SEM studies show that FEC decomposes forming spherical particles, their size being dependent on the cell-cycling conditions. Synchrotron-based X-ray photoemission, XPEEM, allowed us to determine the local surface chemical composition, showing LiF as the main component. In addition, by tracking laterally-resolved surface chemical composition along cycling, we were able to determine that spheres get covered by a film upon further electrolyte decomposition.

Resume : Rechargeable sodium ion batteries (SIBs) have attracted intensive attention due to the similar electrochemical properties to lithium ion battery but the much lower cost. Herein, an innovative bimetallic nickel iron telluride with hierarchically porous nanostructure on carbon paper was firstly synthesized by a facile two-step hydrothermal process. The resulting construction of three dimensional porous nanostructure was benefitting to enhance the electrolyte diffusion and accommodate the volume expansion of metal tellurides during cycling, leading to much better cycling stability. Meanwhile, the coexistence of nickel telluride and iron telluride within this bimetallic telluride contributes to the synergetic effect of providing much richer redox reactions as well as improving the electrical conductivity with a high specific capacity 438 mAh/g at a current density of 25 mA/g. In addition, the detailed electrochemical mechanism of this bimetallic system is going to uncover. It is believed this work paths the way for developing advanced bimetallic tellurides as anode materials for SIBs.

Resume : This project takes an interest in producing a Zinc / Manganese Dioxide rechargeable battery. 4 Type of Manganese Dioxide Polymorphs ?-MnO2 Nano wire, ?-MnO2 Nano wire, ?-MnO2 Nano sheet and ?-MnO2 Nano wire have been synthesised via hydrothermal and oxidation reaction process. Separate morphology of each phase has been tuned using modified synthesis condition. The crystallinity phase and morphology has been investigated using XRD, FESEM and HRTEM. The electrochemical properties of the synthesised materials were then evaluated in a Zinc and Manganese Dioxide Secondary Cell configuration. The ?-MnO2 Nano wire had an advantage over the rest, with a storage capacity of 303mAhg-1 as compared to ?-MnO2, ?-MnO2 and ?-MnO2 with 150 mAhg-1, 95mAhg-1 and 42mAhg-1 respectively. The good capacity was associated with a higher degree of ion intercalation in the 1x1 tunnel structure of ?-MnO2. A review of phase and morphology transformation of MnO2 was also done over an ex situ characterisation technique, providing essential information about the nucleation pattern of MnO2 and useful information for materials design.

Resume : Development of the new Li-conductive materials that are good enough to face the modern requirements is a challenge for contemporary scientists all over the world. The optimal electrolyte is expected to be highly conductive, safe, and affordable. Evidently, chemical and structural stability of any material proposed as an electrolyte affects strictly to all of the goals mentioned. Nevertheless, unfortunately, the aging aspect is poorly described. Current work investigates the aging of Li1.3Al0.3Ti1.7(PO4)3 (LATP) ceramics stored in air and argon. The LATP was chosen as a basic material that is well known to be the most promising solid-state Li-electrolyte suitable for further optimization. The pure LATP was synthesized through the simple solid-state route. The crystal structure of materials obtained and stored in air and argon atmosphere was refined using the Rietveld method applied to the high-resolution Powder X-Ray Diffraction (PXRD) data. The results obtained revealed intrastructural changes that correspond to the degradation process. Additionally, the calculations based on Density Functional Theory (DFT) were applied to investigate the equilibrium lithium positions and support the results obtained experimentally. As a result, the intrastructural unit was successfully defined as a degradation indicator that can represent the performance of LATP ceramics.

Resume : Herein we will discuss the preparation and energy storage performances of a series of Nitrogen doped CNT sponges (CNT-S). The synthesis was done using an Aerosol-Assisted Chemical Vapor Deposition (AACVD) method in a by-sprayer system at a temperature of 1000° by using Benzylamine(BZ)-toluene, BZ-urea, BZ-pyridine, BZ-1,2-Dichlorbenzene (2.5% Ferrocene) and BZ-1,2-Dichlorbenzene (12% Ferrocene) as carbon and nitrogen dopant sources, respectively. SEM, TGA, XPS, XRD, BET, Raman have been used to characterize the composition and morphology of the obtained CNT-S. Next, the electrochemical performances have been assessed and the results compared with commercial CNT and correlated to the composition and morphology. We found the CNT-S to display dissimilar electrochemical performances with the CNT-S sample prepared from 2-Dichlorbenzene (12% Ferrocene) displaying the highest specific capacity (220 mAh/g), highest first cycle efficiency (71.3%) and good retention of (98.4%) at a current density of 25 mA/g after 100 cycles. Oppositely, the CNT-S prepared from 2-Dichlorbenzene displayed the worst performances with an irreversible capacity loss of 75.8% at the first cycle and subsequent poor cycling stability.

Resume : Metal Organic Framework (MOF) based supercapacitor is one of the most talented energy storage devices for future portable electronics. Here, we report in detail the design and low-cost fabrication of an advanced asymmetric supercapacitor (ASC) which was assembled with the Prussian blue (PB)/MnO2 (PB@MnO2) hybrid as the positive electrode and the polyaniline (PANI)/graphene nanopatelets (GNP) (PG) composite as the negative electrode with aq. KNO3 electrolyte. Both the electrodes were prepared by the coating of the respective electrode materials on the conducting stainless steel (SS) fabric. The MOF based positive electrode material, i.e., the PB@MnO2 hybrid was synthesized via reducing agent assisted chemical bath deposition of MnO2 nanolayer on the faradaic PB microcubes and exhibited an appreciable specific capacitance (Csp) of 608 F g-1 at 1 A g-1 current density in the three-electrode measurement and the assembled PB@MnO2//PG ASC device manifested favorable Csp of 98 F g-1 at 1 A g-1. Moreover, this ASC device exhibits significant energy density of 16.5 Wh Kg-1 at the power density of 550 W Kg-1 along with notable long-term cycling stability (retention of 93% capacitance even after 4000 cycles of charging and discharging). Thus, the obtained results reflect great potential of the ASC device for exploring state-of-art futuristic applications as an advanced energy storage system.

Resume : Asymmetric supercapacitor, coupling two different electrode materials having absolutely different working voltages, is an effective way to improve the voltage and hence the energy density. In this work, a high performance asymmetric supercapacitor, consisting of novel electrodes: a polypyrrole (PPy) nanotube (NT)/N-doped graphene (NDG) negative electrode and a MoS2-decorated core-shelled MoO3/PPy positive electrode, is demonstrated. Three dimensional network PPy nanotube/N-doped graphene (NDG) has been synthesized via a facile two step methods, in-situ polymerization assisted by MoO3 template and a microwave-assisted hydrothermal method at short time. The MoO3 template-assisted polymerization is demonstrated as an effective way to control the PPy thickness. It is found that the PPy nanotube formation and N doping of reduced graphene oxide occur simultaneously during the microwave process. Due to the unique structure and high electrical conductivity, the PPy nanotube/NDG shows extremely small ESR of 1.7 ohm, Rc of 0.1 ohm, Rd of 0.1 ohm, and specific capacitance (Csp) of 292 F g-1 at 5 mV s-1. Also, a novel MoS2-decorated core-shelled MoO3/PPy has also been fabricated through a facile method. Owing to the unique structure and rich redox activities, MoS2-decorated core-shelled MoO3/PPy shows excellent performance with Csp of 527 F g-1 at 5 mV s-1 and low charge transfer resistance. The asymmetric supercapacitor shows an excellent energy density of 43.2 Wh kg-1 at power density 674 W kg-1. The asymmetric supercapacitor also shows an excellent retention of 126% after 5000 cycles, possess high potential for application in the energy storage. Keywords: N-doped graphene, PPy nanotube, MoO3, MoS2, asymmetric supercapacitor.

Resume : Developing abundant, active, and stable electrode materials for renewable energy storage and conversion by electrochemical reactions is highly demanded over the past few decades. A remarkable improvement in performances of electrochemical energy storage and conversion system has been achieved through recent advances in metal-oxide based materials. Especially, structural properties of metal oxides for the electrode materials are treated as design factors to realize a high reaction rate, reducing the kinetic imbalances from different reaction mechanisms of different electrodes in practical devices. Recently, we found that the electrochemical approach for controlling the structure of metal oxide nanoparticles at few-nano scale level by reducing the oxidation state of metal ions. In this presentation, technique used in Li-ion battery research will be presented as the new approach for nanostructuring the metal oxides such as NiO, MnO2, and Fe2O3. Nanostructured metal oxide composites were applied to the battery-type electrodes and configured to asymmetric hybrid capacitors with other capacitor-type electrodes. Their highly enhanced electro-active surfaces from their various structural advantages can be the key to success in designing the high-performance devices. We hope that the method and applications demonstrated here could offer a opportunity to discuss ideas for designing the materials for energy storage devices.

Resume : Quinone-based compounds have been extensively explored, with a rich library for quinone-battery chemistries already available. However, solubility in battery electrolytes remains a persisting challenge. With 2,5-diamino-1,4-benzoquinone (DABQ) [1], we come up with a new paradigm in design of new organic battery materials by introducing intermolecular H-bonding and its nature-proven stabilization properties. The existence of these H-bonds in DABQ is evidenced through the resolution of its crystal structure (from PXRD data) and further corroborated with the FTIR spectroscopy data. The resulting stabilization translates into unusually low solubility in organic battery electrolytes. Full material utilization was achieved under galvanostatic cycling (theoretical capacity of 388 mAh.g-1, reversible 2 electrons redox). Furthermore, we optimized the electrolyte formulation in terms of polar momentum, with direct impact on cycling stability of solid-state electrodes. Finally, through ex situ FTIR and in situ PXRD, the chemical and structural changes undergone by DABQ upon reduction were shown to be perfectly reversible, attesting the stability of the redox reaction. Our work paves the way to new design of H-bond stabilized organic molecular crystals for battery applications, with potential for a new strategy towards insolubility of small organic redox compounds. [1] L. Sieuw et al., Chem. Sci., 2019, 10, 418-426

Resume : Development of high performing supercapacitors utilizing the strategy of inserting redox additives into the host electrolyte is increasingly become popular over the last few years. Redox additives, can act as external agents and have the capability of introducing redox couples for improved electrochemical interactions and the resultant specific capacitance. It will be shown that, tuning the hollow morphologies of binary oxides such as: Co3O4, Mn3O4, etc. nanostructures (as positive electrode) can be made economical and industrially viable. These hollow structures show high surface area and induce the expected enhancement in the electrochemical response. But, the main result of the paper is the proposal for combining the strategies of using redox and hollow structures for obtaining high performing supercapacitors. This has still not be investigated or reported in the literature. In this work, the results based on the utilization of K3Fe(CN)6 as a redox additive in 1 M KOH electrolyte with hollow structures of different metal oxides will be presented. The results show the doubling of the observed specific capacitance, in comparison to conventional solid, porous or other similar hierarchical nanostructures. In additions, the fabricated asymmetric supercapacitors can also be operated upto temperatures ?65 °C, which makes them useful for applications in hybrid vehicles, mobiles and wearable electronics.

Resume : In recent years, rechargeable aluminum-ion batteries (AIBs), comprised of Al anode, graphite cathode and a chloroaluminate ionic liquid electrolytes, have emerged as a promising energy storage technology due to its energy density, safety and low-cost. However, commercialization of AIBs will require addressing a series of issues. The acidic character of the electrolyte produces the anodic dissolution of cheap materials commonly used as cathode current collectors, which has been solved at lab-scale by using expensive/scarce current collectors such as W or T. However, our cost analysis reveals, for the first time, that current collector is currently the most expensive element in AIBs hindering the feasibility at large scale. In this work we propose a low-cost carbon-based current collector, i.e. gas diffusion layer (GDL). The use of GDL is an excellent option for AIBs since it contributes to reduce battery cost. From an electrochemical perspective, GDL does not corrode and does not catalyze electrolyte decomposition. Moreover, the performances of AIBs using GDL as current collector are comparable to those using more expensive state-of-the-art materials. This battery can afford a 60 mAh g-1 of capacity during more than 1400 cycles maintaining a coulombic efficiency close to 100%.

Resume : The importance of understanding Li ion diffusion mechanisms in ceramic materials is key when developing solid state Li batteries. LISICON materials, such as LATP, have been studied to include nudged elastic band calculations with DFT [1], diffraction experiments [2] and molecular dynamics calculations [3]. In this work, we report molecular dynamics simulations on a much larger scale at a range of temperatures, over nanosecond timescales, with activation barriers of 0.3 eV in accordance with experimental data. The elucidated migration pathway suggests a vacancy migration involving M1 (6b) and M2 (18e) sites suggesting that the M?1 (6a) site is only a metastable site and disappears at higher temperatures. Furthermore, the Al doped dynamic simulations suggest Li trapping. References [1] B.Lang, B. Ziebarth and C. Elsasser, Chem. Mat. 27:5040-5048 2015 [2] M. Monchak, T. Hupfer, A. Senyshyn, H. Boysen, D. Chernyshov, T. Hansen, K. Schell, E. Bucharsky, M. Hoffmann and H. Ehrenberg, Inorg. Chem., 55:2941-2945 2016 [3] G. Nuspl, T. Takeuchi, A. Weiss, H. Kageyama, K. Yoshizawa and T. Yamabe, J. App. Physics, 86:5584-5491 1999

Resume : Red-Ox flow batteries are considered to be promising for fast and effective energy conversion. To go further, metal lithium as an anode coupled with organic catholyte has potential to meet modern requirements. A key component of such battery is a solid dense electrolyte which will be stable towards Li, possess high conductivity, and flexibility. For this reason, composite ceramic-polymer electrolyte (Li1.3Al0.3Ti1.7(PO4)3 -PVDF/PEO) are being developed. During research, we focused on the quality of the electrolyte. We have studied separately conductivity and aging of ceramic material and composite Li-conductive membrane in various media, which are important for the further processability: air and Ar atmosphere; water and organic solvents. Special emphasis was made on electrochemical impedance technique. Deterioration of conductivity was observed in all cases while its degree depended on duration of exposure and chemical composition of the media. Corroboration with crystallographic structure, SEM, HR-TEM data and a possible mechanism will be discussed during the presentation as well.

Resume : In order to realize highly efficient, safety and miniature energy storage devices for portable electronics devices and grid storage, supercapacitors (SCs) with high power density, relatively high energy density and long cycle life are among the most promising candidates. Due to the high theoretical specific capacitance, high surface area and low toxicity, 2D MnO2 nanosheets show great potential as active materials for SCs. Recently, MnO2 nanosheets were ink-jet printed on flexible polyimide substrate and used as active materials for micro-supercapacitors (MSCs).1, 2 However, the performance of printed MnO2 nanosheet MSCs is limited because of the low electron conductivity. Atomic-level structure engineering like substitutional doping with foreign elements is a strategy to substantial modification of physical and chemical properties of materials. We prepared Fe, Co, and Ni-doped MnO2 nanosheets with a sheet thickness smaller than 2 nm. By engineering the formulation of doped MnO2 nanosheets solutions, we were also able to ink-jet print nanosheet electrodes on polyimide substrates. Using experimental data, cutting edge structural and chemical characterization, and density functional theory calculations, we show the relationship between dopant and capacitance, and demonstrate why Fe-doped MnO2 nanosheets have the best electrochemical performance. 1. Y. Wang, Y.-Z. Zhang, D. Dubbink and J. E. ten Elshof, Nano Energy, 2018, 49, 481-488. 2. J. E. ten Elshof and Y. Wang, Small Methods, 2018, 0, 1800318.

Resume : In this work, polyaniline/MWCNTs nanocomposites have been prepared by in-situ addition of 2 and 5 weight % MWCNTs as fillers in the polyaniline matrix. The nanocomposites were then characterized via scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), UV-Vis spectrophotometry in order to observe the morphology, phase, thermal stability and optical properties of the samples, respectively. SEM results showed that CNTs were fairly dispersed in the polyaniline matrix while XRD results showed a broad peak for nanocomposites due to amorphous nature of polymers. TGA analysis results showed that both CNTs and polyaniline were stable up to 350 ºC and UV-Vis spectrophotometry results showed that nanocomposites were active in both UV and visible light region of electromagnetic spectrum. The electrochemical properties of the samples were then analyzed via cyclic voltammetry (CV), galvanostatic charge-discharge cycles (CED) and Electrochemical Impedance Spectroscopy (EIS). Polyaniline/ 5 wt.% CNTs nanocomposites showed the highest capacitance of 1535.45 Fg-1 at 1 A/g, this composite shows the lowest charge transfer resistance(Rct).

Resume : Li-ion batteries are promising power sources for portable electronics and electric vehicles due to their high energy density. However, its application in grid storage is limited due to high cost and low abundance of Li resources. Sodium-ion battery seizes attention of the scientific community due to negative potential (-2.71 V Vs SHE) and highly abundance of Na in earth?s crust. Recently, various research groups have demonstrated interesting results based on Na+-ion intercalating behaviour in metal oxides and polyanionic cathode materials.1 Still there exist ample room for discovery and development of Na-ion cathode materials moving the focus from oxide to mixed polyanionic chemistry.2 Recently, Goodenough et al., reported NaFe2PO4(SO4)2 with NASICON framework and demonstrated Na/Na1+xFe2PO4(SO4)2 cell operating on the Fe3+/Fe2+ redox couple.3 The hexagonal NASICON framework structured NaFe2-xVx(SO4)2PO4 has low cost and 3D intercalation properties. Here, we report a Na-ion intercalating properties of Fe and V based mixed-polyanion NaFe2-xVx(SO4)2PO4 and Na4Fe3(PO4)2P2O7. The cathode materials were prepared by solution combustion synthesis technique. The crystal structure of Na4Fe3(PO4)2P2O7 was identified to be orthorhombic with Pna21 symmetry from Rietveld refinement. It has a 3D intercalating structure for Na-ion with a theoretical capacity of 129 mAh g-1.4 The Na-ion cell with the carbon coated Nano-Na4Fe3(PO4)2P2O7 cathode delivered a discharge capacity of 125 mAh g-1 at a 0.1C rate. Similarly Na-ion cell with the NaFe2-xVx(SO4)2PO4 cathode showed a discharge capacity of ~80 mAh g-1 and excellent rate capability with good cycling stability. The work demonstrates the capability of the materials as high performance Na-ion battery cathodes due to its 3D Na-ion intercalating path ways and multiple Na-ion sites in the structure. References 1. N. Yabuuchi, S. Komaba et al., Chem. Rev. 2014, 114, 11636. 2. B. Senthilkumar, P. Barpanda et al., Small Methods, 2018, DOI:10.1002/smtd.1800253. 3. K. Shiva, P. Singh, J.B. Goodenough et al., Energy Environ. Sci., 2016, 9, 3103. 4. B. Senthilkumar, P. Barpanda et al., ECS Transactions, 2018, 85, 227.

Resume : In the current rechargeable lithium-ion battery technology, several issues occurred with the present cathode materials, which led to a vast new research area in search of new rechargeable battery systems. Lithium-sulfur is one such system that has a high theoretical specific capacity and energy. Among the various candidate materials, porous carbons, especially porous reduced graphene oxides have received great attention since they provide a high surface area, electrically-conductive framework on which insulating sulfur can be made electrochemically active when properly dispersed. In this work, the performance of a chemically prepared porous reduced graphene oxide (PRGO) with high surface area as a cathode material for Li-S batteries was reported. The porous structure of the PRGO originating from interconnected pores makes the total available surface area highly accessible, resulting in excellent electrochemical properties. The PRGO cathode material was characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), Thermogravimetric analysis (TGA), and Raman spectroscopy. Specific surface areas and pore volumes was studied using Nitrogen adsorption and desorption method. The battery characteristics of PRGO were studied at various current densities. At high C-rates (1C-5C), large specific capacities ranging from ~778 to ~400 mAhg-1 were obtained after 250 cycles. Interestingly, the excellent electrochemical response in terms of charge/discharge capacity, rate capability, cyclic performance, was obtained even at high temperature (~90 0C), and showed high thermal stability of the batteries. The developed PRGO in this work would be an excellent electrode material for safe future Li-S batteries technology.

Resume : Silicon is a good candidate to replace current anodes in lithium-ion batteries [1]. Silicon crystals are used with their native oxide (SiOx) layer and, upon lithium intercalation, Li ions interact first with the SiOx, and subsequently alloy with Si, forming LixSi (x< 4.2)[2]. Detailed studies on the solid electrolyte interphases (SEI)[3-4] are of fundamental importance in understanding capacity-fading effects[5-6]. Thus, the SEI then plays a crucial role. Two different half Li/Si cells were prepared, one Si electrode with and one without native oxide layer, removed using hydrofluoric acid. The composition of electrolyte was 1 M LiPF6 salt in EC:DMC organic solvent mixture (1:1 vol.%), and lithium metal as cathode. The half-cells were cycled between open circuit voltage and 0.01 V in galvanostatic charge and discharge (250 µA). Potentiostatic Electrochemical Impedance Spectroscopy measurements were performed within the frequency range 1 MHz?0.1 Hz in both charged and discharged states. We performed in-situ neutron reflectometry measurements on both cells, combined with electrochemical measurements. Neutron reflectometry is a surface sensitive technique and allows direct measurement of both thickness and chemical composition of the SEI layer[7-8], due to the scattering length density contrast between Li (-0.88?10^{-4} nm-2) and Si (2.07?10-4 nm-2). We observed a structural evolution of the SEI layer as a function of the electrochemical state, indicating the formation of a Li rich layer (approximately 20?50 nm) at the surface of the silicon, possibly lithium silicon oxide or lithium oxide. [1] Zuo, X.; Zhu, J.; Müller-Buschbaum, P.; Cheng, Y.-J., Nano Energy 2017, 31, 113-143. [2] Nazri, Gholam-Abbas; Pistoia, Gianfranco, eds. (2004). Lithium Batteries - Science and Technology. [3] Michan, A. L., Divitini, G., Pell, A. J., Leskes, M., Ducati, C., & Grey, C. P. , Journal of the American Chemical Society, 138 7918-7931 [4] Yang, J.; Kraytsberg, A.; Ein-Eli, Y. , J. Power Sources 2015, 282, 294?298 [5] E. Grass, Z. Liu, V. S. Battaglia, and G. Liu , J. Electrochem. Soc. 2011 158(12): A1260-A1266; [6] Kjell W. Schroder, Anthony G. Dylla, Stephen J. Harris, Lauren J. Webb, and Keith J. Stevenson, ACS Applied Materials & Interfaces 2014 6 (23), 21510-21524 [7] B. Jerliu, L. Doerrer, E. Hueger, G. Borchardt, R. Steitz, U. Geckle,V. Oberst, M. Bruns, O. Schneider and H. Schmidt, Phys. Chem. Chem. Phys., 2013, 15 , 7777 [8] A. Ronneburg, M. Trapp, R. Cubitt, L. Silvi, S. Cap, M. Ballauff, S. Risse, Energy Storage Materials, 2018, 10.1016/j.ensm.2018.11.032.

Resume : Sodium-ion batteries have attracted considerable attention due to the abundance of sodium and the lower cost comparing to lithium-ion batteries, making it a promising candidate for next-generation secondary batteries. Previous studies have shown that tellurium can be a suitable cathode material for both lithium- and sodium-ion batteries by impregnating it into a porous carbonaceous material. However, this method is time-consuming and usually requires the use of binders and collectors, which would limit the full utilization of the active material. In this study, van der Waals tellurium nanoflakes were successfully grown on copper foil through a physical vapor deposition process. Contrast to previous reports of utilizing Te by melt diffusion as a result of the helical structure, Cu was able to trigger the layer stacking of Te, which was so called quasi-tellurene. Subsequently, a binder- and collector-free sodium-ion battery was assembled, and it delivered a high reversible capacity of 2658 mAh cm?3 at the current density of 100 mA g?1. Furthermore, it also showed fast rate capability (1707 mAh cm?3 at the current density of 5000 mA g?1) and a cycling test at the current density of 100 mA/g revealed a capacity retention of ~98.6 % after 200 cycles. These remarkable electrochemical performances could be attributed to the superior electronic conductivity in nature as well as the layer structure.

Resume : With increasing demand on Li ion batteries with a high energy density, the graphite anode becomes thicker and denser. However, the severe swelling behavior of the thick and dense graphite electrode results in the degradation of electrochemical properties. In this study, we report the microstructural engineering strategy of graphite electrode to control of swelling behavior by using two-step pressing process. By employing this pressing process, the porosity distribution, electrolyte permeability, and adhesion strength of the graphite electrode could be significantly enhanced. The uniform pore distribution enables the efficient relaxation of the stress applied to the graphite during cycling. The enhanced electrolyte permeability and adhesion strength improve the electrochemical properties such as coulombic efficiency, cycle retention, and rate capability.

Resume : Energy storage has been developed to be used in electric vehicles(EVs) in recent years and has not been fully exploited for their small energy and power densities and long hours of charging time. The lack of electrical energy demand is being met by the development of energy storage systems (ESS) through numerous novel electrode materials and new types of energy storage devices Hybrid energy storage, which is composed of different positive and negative electrodes with different charge storage mechanisms, is a next-generation energy storage device that realizes high performance and is emerging as a solution to electric energy problems. Generally, it is an asymmetric cell assembled with a redox-active (pseudocapacitive and battery-type) positive electrode and an EDLC-type negative electrode and shows the improvement of operating voltage. On the other hand, EDLC-type carbon materials are mainly used as negative electrode, and the charge storage capacity is significantly smaller than that of the positive electrode. Therefore, along with the development of hybrid energy device, it is necessary to develop a new negative electrode material that exceeds the performance of commercialized activated carbon (AC). Herein, we have implemented a high performance electrode that is driven both in aqueous and nonaqueous media using a graphene-based pseudocapacitive polymer chain composite. The fiber-shaped polyaniline(PANI) and graphene composite shows pseudocapacitive properties with high conductivity, and have a high specific capacitance value of 445 F/g over the carbon material (~ 300 F/g) in aqueous electrolyte as supercapacitor anode and a high specific capacity value of 80 mAh/g beyond commercial AC in nonaqueous electrolyte as a battery cathode. Indeed, assembling the negative electrode with the positive electrode is shown to exhibit high performance as hybrid energy storage.

Resume : Ferrocyanide (FCY) based alkaline redox-flow batteries are considered promising alternatives to traditional redox-flow batteries that are based on high cost and strategic metals and corrosive acidic media. FCY has been used as active species in the positive side of a variety of redox-flow batteries, e.g. anthraquinone/FCY and phenazines/FCY. However, in all these cases, the energy density is limited by the low solubility of FCY in alkaline media (0.4 M equivalent to 10 AhL-1). In contrast, electroactive solid species that are frequently used in non-flow batteries are able to store more charge per unit volume than soluble electroactive species, e.g. Ni(OH)2 has a volumetric capacity of 1180 Ah·L-1 that is two orders of magnitude higher than that of a FCY solution. However, solid materials cannot be used in flow batteries as there is no electrical contact between the electrode and the solid located in the external tank. In this talk, we will show that soluble electroactive species can be also used as molecular wiring to transport charges to high-energy solid materials confined in the external reservoir. We demonstrate that by adding solid material in the reservoir, volumetric capacities of >25 AhL-1 are achieved (40% utilization rate of Ni(OH)2). We apply the concept in two types of FCY flow batteries: quinone/FCY and phenazines/FCY. For the latter, energy densities of >15 WhL-1 are demonstrated representing the highest value for an alkaline flow battery

Resume : Fiber-shaped supercapacitors (FSCs) have great promises in wearable electronics applications1-4. However, most of reported FSSs are operated at room temperature and may have safety hazards at harsh environmental temperatures. The performance of the FSCs may deteriorate at extreme temperatures which results in issues such as capacitance decay, internal resistance increase, cycle life degradation and thermal runaway triggered by thermal stress from internal heat generation, which severely limit the practical application. Here we reported a new kind of aqueous symmetric FSCs with high safety and record high areal energy density at wide operating temperature ranging from -60 ?(14.2 µW h cm-2) to 75 ? (22.9 µW h cm-2) based on aqueous LiCl-PVA based gel electrolyte and core-shell nanocrystalline polymer fiber electrode. The fabricated aqueous FSSs demonstrate high flexibility, high areal/volumetric energy density and stable cycle life at different operating temperatures, showing the potential application in all-climate wearable electronics. 1. Wang, Z.; Cheng, J.; Zhou, J.; Zhang, J.; Huang, H.; Yang, J.; Li, Y.; Wang, B., All-climate aqueous fiber-shaped supercapacitors with record areal energy density and high safety. Nano Energy 2018, 50, 106-117. 2. Wang, Z.; Cheng, J.; Guan, Q.; Huang, H.; Li, Y.; Zhou, J.; Ni, W.; Wang, B.; He, S.; Peng, H., All-in-one fiber for stretchable fiber-shaped tandem supercapacitors. Nano Energy 2018, 45, 210-219. 3. Zhou, J.; Li, X.; Yang, C.; Li, Y.; Guo, K.; Cheng, J.; Yuan, D.; Song, C.; Lu, J.; Wang, B., A Quasi-Solid-State Flexible Fiber-Shaped Li-CO2 Battery with Low Overpotential and High Energy Efficiency. Advanced materials (Deerfield Beach, Fla.) 2018, e1804439-e1804439. 4. Qu, G.; Cheng, J.; Li, X.; Yuan, D.; Chen, P.; Chen, X.; Wang, B.; Peng, H., A Fiber Supercapacitor with High Energy Density Based on Hollow Graphene/Conducting Polymer Fiber Electrode. Advanced Materials 2016, 28, (19), 3646-3652.

Resume : Recent demands on energy storage opened up many challenges and opportunities in the domain of electrochemical devices such as batteries and supercapacitors. Supercapacitors are known for high power supply in short time, long life cycle and eco-friendly operation. Owing to its remarkable properties, graphene (single layer of graphite) ? an allotrope of elemental Carbon and a 2D material discovered in 2004 ? has emerged as a promising active-electrode material for developing high-performance supercapacitors. We explored unconventional transition metal salts-based reducing agents in the chemical reduction of GO to rGO and fabricated all solid-state supercapacitor. The overall supercapacitive performances of here produced rGOs were found to be in the range of ~170-250 F/g at a current density of 1 A/g along with >100000 charge-discharge cycles which is much superior in comparison to rGO obtained by conventional reducing agents such as NaBH4, and N2H4. Also, here produced rGO showed excellent rate performance. Finally, our process of producing rGO by the top-down chemical approach in large scale was realized to be highly economic and thereby promising for supercapacitor applications in industrial level.

Resume : Realization of safe electrochemical energy storage systems (ESS) with high energy density and high power density enabling fast charge/discharge is a major issue. Here, we report a strategy to achieve high-performance in aqueous systems using porous Mn3O4 (p-MG) positive and porous Fe2O3 (p-FG) negative electrodes, where granular nanoclusters composing nanoparticles have been produced on graphene through lithiation-induced conversion. The additional active sites from enlarged specific surface area and shortened ion diffusion lengths in p-MG and p-FG provide fast charging/discharging rate and excellent cycle stability. We find that porous metal oxide structures play mainly as redox reaction sites, while graphene structures provide electrical conductivity to active sites. Furthermore, the asymmetric configuration composed of p-MG positive and p-FG negative electrode in a hybrid capacitor shows a distinguished high energy density exceeding those of aqueous batteries, in addition to excellent capacity retention over 30,000 redox cycles and the energy density which is 2.5-fold higher than that of its counterpart with pristine Mn3O4 and Fe2O3 nanocrystals. Moreover, this device shows the wide operating voltage and high power density allowing ultra-fast charge that the full cells in series can be charged within several seconds by the rapid USB charger.

Resume : Ion implantation is an important doping technique, which is widely used in thefields of micro-electronics and surface modification ofmaterials. During implantation, energetic ions are injected into target,in whichthe physicochemical property of the material can be selectivelychanged. In this study, the fabrication and performances of a Cu-ion-implanted Si filmwhich used as lithium ion battery anode has been investigated. The implanted Si film anode exhibits an improved performance comparing with the original film, in which the discharge and charge capacity in the second cycle areabout 1045 and771mAh/gat the current density of 1000 mA/g. After 300 cycles, the discharge capacity of 669mAh/g and charge capacity of 652mA/g are kept. A further investigationindicates that the formation of Cu-Si alloy in the implanted Si filmmade the anode more stable. We ascribe the result by the remitted stress of volume expansion during cycling.At the same time, Cu ions implantation reducesimpedance of the anode andenhancedelectrochemical activity of anode materials.

Resume : A 3D free-standing lithiophilic silver nanowire aerogel (AgNWA) synthesized by a modified polyol reduction method using a cheap silver nitrate precursor is proposed as an ideal host of lithium metal for high-energy lithium metal batteries, which are considered as disruptive and next-generation energy storages. The lithiophilic property of Ag was also quantitatively investigated by the density functional theory (DFT). AgNWA having the lithiophilic property can stop the dendritic growth of lithium metal at the initial nucleation process and its 3D structure can also suppress the infinite volume expansion of lithium during cycling. The active AgNWA scaffold encapsulates Li in the Li-Ag intermetallic phases serving as a Li reservoir to compensate the irreversible consumption of Li. In addition, the ?-cubic Li-AgNWA anode having the lowest formation energy is also coupled with lithium iron phosphate (LFP) cathode with the Li-AgNWA alloy utilization of ca. 60%. The smaller lattice parameter changes were observed for LFP coupling with ?-cubic Li-AgNWA anode as compared with pure metallic Li as investigated by in operando XRD. The dendrite-free Li-AgNWA with a good lithium affinity could be an ideal anode of high-energy Li-metal batteries for uses in many applications.

Resume : Cobalt disulfide is popular as cathode in the application of thermal battery with high power density, small volume and long working life, ascribed to its high thermal stability and electron conductivity. To achieve higher ability, improving the performance of the CoS2-based cathode for thermal battery is becoming more and more important. In this research, element Fe was adopted to modify the crystal structure and surface, and the effects were investigated in details, including the thermal & storage stability and discharge capacity. Furthermore, the composition of FexCo1-xS2 ?0< x< 1?exhibiting the best was determined.

Resume : The metastable, bronze phase of titania (TiO2-B) has great potential as anode material in Li-ion batteries. For this purpose, colloidally stable nanocrystals (NCs) of TiO2-B are desired, with tunable size and surface chemistry. Existing synthetic methods deliver NCs suffering from phase impurities and extensive agglomeration. Here,[1] we employ definitive screening design to identify the significant experimental parameters affecting the size and agglomeration of the NCs, formed through thermal decomposition of a titanium peroxo complex. The size is mostly determined by the reaction temperature, resulting in monodisperse 3 ? 8 nm NCs in the range of 130 °C ? 180 °C. To avoid irreversible aggregation, the reaction time ought to be minimized, hence microwave heating is required. The resulting NCs are colloidally stabilized in polar solvents using either positive or negative surface charges. In nonpolar solvents, steric stabilization is provided by alkylamines and fatty acids. Through NMR spectroscopy, we find ion-pairs of alkylammonium carboxylates bound to the surface, contrasting with earlier reports on carboxylic acid stabilized metal oxide nanocrystals. Finally, by having complete control over the surface chemistry and access to agglomeration-free, size-tunable NCs, the tools are provided for polymer templated porous anodes with the potential to greatly advance the charge and discharge rate in Li-ion batteries. [1] Billet J. et al. Chem. Mater. 2018, 30, 4298

Resume : By adjusting atomic ratio of metal and sulphur, sulfides with different phases can be designed with enhanced electronic conductivity for better performance. Herein, hexagonal-phase NiS octahedrons were synthesized through heat-treatment method, which were co-modified by multi-dimensional carbon materials, i.e. 0D carbon QDs, 1D CNTs, and 2D reduced graphene oxide. The composite delivers a significantly enhanced specific capacity of 1577 F g?1 at a current density of 1 A g?1, and a capacity up to 976 F g?1 at 20 A g?1, superior to its counterparts. Furthermore, asymmetric supercapacitors (ASC) assembled by the composite and graphene hydrogel achieve a remarkable cycling stability (capacitance retention of 82 % after 5000 cycles). The excellent supercapacitor could be ascribed to the chosen hexagonal-phase NiS octahedrons (providing more active sites), the co-modified 0D, 1D, and 2D carbon structures (shortening electron transfer distance), and the considerable C-S bonds linking the active material and the conductive substrates.

Resume : Graphene-based electrode materials for supercapacitors usually suffer from poor volumetric performance due to the low density. The enhancement of volumetric capacitance by densification of graphene materials, however, is usually accompanied by deterioration of rate capability, as the huge contraction of pore size hinders rapid diffusion of electrolytes. Thus, it is important to develop suitable pore size in graphene materials, which can sustain fast ion diffusion and avoid excessive voids to acquire high density simultaneously for supercapacitor applications. Accordingly, we propose a simple solvent evaporation method to control the pore size of graphene powders by adjusting the surface tension of solvents. Ethanol is used instead of water to reduce the shrinkage degree of graphene powder during solvent evaporation process, due to its lower surface tension comparing with water. Followed by the assistance of mechanical compression, graphene powder having high compaction density of 1.30 g cm-3 and a large proportion of mesopores in the pore size range of 2–30 nm is obtained, which delivers high volumetric capacitance of 162 F cm-3 and exhibits outstanding rate performance of 76% capacity retention at a high current density of 100 A g-1 simultaneously.

Resume : The spinel ferrite nanomaterial was synthesized by Sol-Gel technique. Sample morphology and structure were investigated by SEM, XRD and EDX techniques. The electrochemical behaviour of the sample was studied using chronopotentiometry technique. The electrochemical study reveals that the electrode is activated during the third cycle by taking an electrochemical discharge capacity in the order of 143 mAh/g and all electrochemical parameters evolve in practically the same direction, which proves the good electrochemical behaviour of the compound studied.

Resume : In a few decades, Li-based battery technologies have become the state of the art electrochemical energy storage device and found numerous applications, notably in portable electronics. The first Li-MoS2 cells, with specific energy two or three times higher than Ni/Cd or Pb/acid cells, were quickly withdrawn from the market because of dendrite growth at charge, which may cause internal shorts leading to overheating and safety hazards. As an alternative, Li-ion batteries, commercialized by Sony in 1991, rely on lithium insertion in carbon anodes to avoid the use of lithium metal, which implies a weight and volume penalty. In contrast with Li metal anode, electrodeposition of Mg and Ca does not seem to be plagued with dendrite formation. [1,2] This brings the perspective of high-energy metal anode based batteries without the safety concerns associated with dendrite growth. In addition, Ca and Mg battery technologies would benefit from the high abundance of Ca and Mg (5th and 8th most abundant elements on the Earth’s crust, respectively, whereas Li is the 25th), implying lower cost of the raw materials (\$5000/ton, \$100/ton and \$265/ton for Li2CO3, CaCO3 and MgO2, respectively). These attractive features led to significant increase of the research effort dedicated to theses systems for the last few years. However, running electrochemical tests in Ca2+ or Mg2+ based electrolytes is not as straightforward as it is today with Li+. On one hand, the plating and stripping of Ca and Mg still requires specific conditions either in term of electrolyte formulation or operating temperature, which limits the possibility of testing new materials for these systems when a metallic counter electrode is used. On the other hand, it was shown that Ca and Mg metals are also poorly reliable reference electrodes in conventional organic battery electrolytes. [3] This severely limits the combinations of solvents, electrolyte salts and temperatures in which materials for Ca or Mg batteries can be tested. In this work, we evaluated the stability of various types of reference electrodes based on silver in conventional organic electrolytes. Using such a reference in combination with a capacitive counter electrode made of carbonaceous material provides a versatile electrochemical setup for the testing of materials for Ca or Mg batteries. [1] M. Matsui, J. Power Sources, 196 (2011) 7048-7055. [2] A. Ponrouch, C. Frontera, F. Bardé, M.R. Palacín, Nat. Mater., 15 (2016) 169-172. [3] D. S. Tchitchekova, D. Monti, P. Johansson, F. Bardé, A. Randon-Vitanova, M. R. Palacı́n, A. Ponrouch, J. Electrochem. Soc., 164 (2017), A1384-A1392

Resume : Due to serious concerns about future availability and price increase of lithium minerals, several alternatives have been investigated to substitute lithium-ion batteries in high demand applications. Divalent-cation chemistries, such as calcium and magnesium, promise a high energy capacity relying on much more abundant elements (5th and 8th, respectively, in the earth crust) than lithium (25th). Until recently, the development of such battery concepts was focused on electrolytes that do not form passivation films (solid electrolyte interphases - SEI) on the metal surface [1]. These electrolytes, however, suffer from a low stability towards oxidation and thus, limit the output voltage of the assembled cells. Previous works from our group demonstrated calcium plating and stripping in SEI-forming electrolytes at moderate temperatures [2]. Specifically, redox activity of calcium metal was observed in a Ca(BF4)2 electrolyte dissolved in a mixture of cyclic carbonates, while no activity was observed when TFSI was used as anion. The current study focuses on understanding the chemical composition differences between the SEI layers formed in the two systems analysed. A systematic characterization of the SEI formed on the Ca metal anode in various electrolyte formulations will be presented and the most suitable SEI compounds in terms of divalent cation mobility will be discussed. References [1] J. Muldoon, C. B. Bucur and T. Gregory, Chem. Rev., 2014, 114, 11683–11720. [2] A. Ponrouch, C. Frontera, F. Bardé and M. R. Palacín, Nat. Mater., 2016, 15, 169–172.

Resume : The massive infiltration of electrified mobile applications has stimulated the demand for lithium-ion batteries with high energy density and high power. Worldwide, many initiatives are in progress to gradually improve the power or energy performance metrics, with different marketing or scientific schemes implemented. Blending cathode materials is a new approach intended to achieve better balanced electrochemical performance than that of an individual compound [Satishkumar B. Chikkannanavar, Dawn M. Bernardi, Lingyun Liu, A review of blended cathode materials for use in Li-ion batteries, Journal of Power Sources, 248 (2014) 91-100]. In order to achieve improved electrochemical features coupled with thermal stability, two configurations were considered: a complete physical mixture (NMC-LFP) and layered-type blend (LFP-NMC). We have investigated the architecture, the structural and morphological properties, and the electrochemical performance in Half-cell configuration of the blended cathodes compared to pure NMC and LFP. Best electrodes were integrated into full-cell pouch cell type, and the energy-power and cycling performances are discussed.

Resume : Next generation rechargeable batteries that go beyond the currently leading lithium-ion technology and replace lithium with sodium, awakened high interest in the past. This is mainly due to the high natural abundance and low cost of sodium, as well as the possible use of aluminum as current collector. Designing a suitable anode, however, is still a major problem. Avoiding host materials for ions and using sodium metal as an anode would be the ideal case, since metal anodes - Na as well as Li - offer theoretically the highest possible energy density in the respective batteries. Failure due to dendrite growth and persistent decomposition of electrolyte, however, still preclude the application of metal anodes. Finding a solution to these problems is furthermore rendered difficult by the simultaneous influence of many battery elements, including - but not limited to - the electrolyte, separator, nature of the current collector, cell architecture and the cycling procedure. One might find himself for example discarding an electrolyte, because the respective half-cells fail after a few cycles, while a simple change of the utilized separator could have led to hundreds of stable cycles. Facing the problem of dealing with many interacting components within a commonly used half-cell and the inconsistency in literature, a comparative study of many different influence factors is conducted here as a baseline for further improvements of Na-metal anodes. With this we also try to shine some light on why many research groups find it so difficult to assemble half-cells with reproducible cycling behavior and why the performance of seemingly similar half-cells in literature can vary drastically from article to article.

Resume : Electrically rechargeable Zn-air batteries (ZABs) boast high theoretical energy densities at low cost with minimal safety concerns. As such, ZABs have garnered interest as a promising technology for energy storage. However, ZABs suffer from poor cyclability and slow kinetics of the oxygen reactions for charge and discharge, both of which occur at the air electrode. Catalysts are often added to the surface of a gas diffusion layer (GDL) to act as the air electrode and improve the kinetics of the discharge and charge reactions. As the battery is cycled, electrolyte will pass the catalyst layer and performance will be reduced in a phenomenon known as flooding. The current study has developed a two-fold solution; i.e., synthesis of high performing catalysts for the oxygen reactions and a simple preparation technique to reduce the effects of flooding during cycling while improving performance. The former is achieved by decorating nitrogen-doped carbon nanotubes (N-CNTs) with various metal oxide nanoparticles (such as Mn, Co or Fe oxides), while the latter is achieved by impregnating the porous GDL with the N-CNT based catalyst. Both synthesis and electrode preparation are combined in a simple one-pot process. Preliminary battery testing for electrodes impregnated with Mn oxide on N-CNTs shows discharge performance comparable with Pt-Ru catalysts, with an initial discharge potential of 1.19 V (at 20 mA/cm2) and a drop of only 30 mV in discharge potential over 100 h (200 cycles).

Resume : Lithium air (Li-O2) batteries promise a drastic increase in energy densities compared to Lithium-ion batteries based on intercalation-type materials. Considering mass and volume of non-active materials, real performance improvements are only achieved if lithium peroxide (Li2O2) is packed as dense as possible in the nanoporous cathode host. [Freunberger, S. A. , Nature Energy 2, 17091 (2017)]. To understand how structural features of the formed Li2O2 and dynamic phenomena during product growth determine the discharge capacity, quantitative real-time in situ metrologies with structural information at the atomic to micron level are required. Here we present operando small and wide angle X-ray scattering as a novel method to study the morphological evolution of Li2O2 during charging and discharging a custom-built in situ Li-O2 cell. For data analysis a recently developed method was adapted [Prehal, C. et al., Nature Energy 2, 16215 (2017)] and synergistically combined with modelling of Li2O2 nucleation and growth in a realistic 3D carbon pore model. In this way we are able to visualize the product formation in the carbon cavities and distinguish between Li2O2 formed via disproportionation or second electron reduction. By systematically varying the carbon electrode and electrolytes? solvation strength we show novel insights regarding the reaction mechanism and derive conclusive design criteria for optimized Li-O2 cells.

Resume : The redox chemistry of O2 moieties has come into the focus of much of the forefront battery research such as metal-O2 batteries and Li-rich layered oxides (Nature Mater. 2012, 11, 19. Science 2015, 350, 1516). O2 evolution is in either case a critical yet not fully understood phenomenon (JACS 2016, 138, 11211). For example, operation of the rechargeable metal-O2 batteries depends crucially on the reversible formation/decomposition of metal (su)peroxides at the cathode on discharge/charge. So far these parasitic reactions have been ascribed to the reactivity of superoxide and peroxide. Yet, their reactivity cannot consistently explain the observed irreversible processes. Only better knowledge of parasitic reactions may allow them to be inhibited. Here we discuss our recent insights into irreversible parasitic reactions caused by the highly reactive singlet oxygen (1O2) during cycling of non-aqueous batteries that have so far been overlooked. They account for the majority of the parasitic products on discharge and nearly all on charge in metal-O2 cells (Nature Energy 2017, 17036. Angew. Chem. Int. Ed., 2017, 56, 15728). We report on the formation mechanism of 1O2 and a new class of quenchers. Moreover, 1O2 forms upon oxidizing Li2CO3 above 3.8 V vs Li/Li+ (Angew. Chem. Int. Ed. 2018, 57, 5529). Li2CO3 is a universal passivating agent in Li-ion battery cathodes and decisive in interfacial reactivity. Li2CO3 formation, even at impurity levels, will deleteriously affect the stability of all Li batteries that operate beyond 3.8 V vs Li/Li+, which includes most currently-studied cathode chemistries. Awareness of singlet oxygen gives a rationale for future research towards achieving highly reversible cell operation.

Resume : The lithium-sulfur (Li-S) battery is a promising next generation battery technology, much due to the abundance and low cost of sulfur and a promise of high specific energy density. However, obstacles remain preventing commercialisation, one being the insulating nature of sulfur (S8) and another the precipitation of short polysulfides (Li2S), resulting in low utilization of the active materials, poor rate capability, and high cell over-potential, which all reduce the energy efficiency.1,2 Here we propose to use redox mediators (RMs) as electrolyte additives to facilitate the electrochemical processes. RMs are molecules with reversible redox couples, which act as electron transfer agents between the electrode surface and the active material.3,4 Here suitable RMs were first selected by physico-chemical characterization, focusing on the chemical stability vs. electrolyte and polysulfides. Second, the Li-S battery cell cycling performance including cycle-life was studied using different electrochemical analysis methods. We conclude that the RMs kinetically control the precipitation of S8/Li2S ?resulting in lower over-potentials and improved capacity, and hence the use of RMs might be a path to achieve a more complete reaction scheme. This research has received funding through the HELIS project (European Union?s Horizon 2020 research and innovation program under Grant Agreement No. 666221). References 1 J. Scheers, S. Fantini and P. Johansson, J. Power Sources, 2014, 255, 204?218. 2 Z.-W. Zhang, H.-J. Peng, M. Zhao and J.-Q. Huang, Adv. Funct. Mater., 2018, 28, 1707536. 3 S. Meini, R. Elazari, A. Rosenman, A. Garsuch and D. Aurbach, J. Phys. Chem. Lett., 2014, 5, 915?918. 4 G. Li, L. Yang, X. Jiang, T. Zhang, H. Lin, Q. Yao and J. Y. Lee, J. Power Sources, 2018, 378, 418?422.

Resume : Lithium/sulfur (Li/S) batteries have a fivefold higher theoretical gravimetric energy density (2680 Wh/kg) than state-of-the-art lithium ion batteries [1]. However, the strong capacity fading with increasing cycle number is still a major obstacle to a broad technical utilization despite decades of research. Operando techniques [2] are very suitable tools to gain mechanistic understanding of degradation processes. Especially the simultaneous combination of several independent measurements (multidimensional) while the Li/S cell is in operation allows deep insights into the degradation mechanisms and provides further mechanistic understanding of the complex Li/S chemistry. Here we present results of a novel setup where up to five independent measurements are simultaneously performed. Electrochemical impedance spectroscopy (EIS), UV-vis spectroscopy, temperature measurement and X-ray imaging [3] or neutron small angle scattering were performed over several cycles while the cell was galvanostically or potentiostatically charged and discharged. Structural changes on the macroscopic and microscopic scale can be correlated to characteristic signals in the EIS, charge-discharge curve and UV-vis spectroscopy. References: [1] X. Fan, W. Sun, F. Meng, A. Xing, J. Liu, Advanced chemical strategies for lithium-sulfur batteries: A review, Green Energy Environ. 3 (2017) 2?19. doi:10.1016/j.gee.2017.08.002. [2] J. Tan, D. Liu, X. Xu, L. Mai, In situ/operando characterization techniques for rechargeable lithium-sulfur batteries: a review, Nanoscale. (2017) 19001?19016. doi:10.1039/C7NR06819K. [3] S. Risse, C.J. Jafta, Y. Yang, N. Kardjilov, A. Hilger, I. Manke, M. Ballauff, Multidimensional operando analysis of macroscopic structure evolution in lithium sulfur cells by X-ray radiography, Phys. Chem. Chem. Phys. 18 (2016) 10630?10636. doi:10.1039/C6CP01020B.

Resume : Silicon is an ideal anode material for Li-ion batteries, provided it can accommodate the large volume changes between charging and discharging. We present a method, based on Plasma Enhanced Chemical Vapor Deposition (PECVD), to create self-organized nano-structured silicon layers, which can accommodate the large volume changes. Large advantage of this method is that it does not require any pre- or posttreatment of the silicon to obtain the nano-structuring and high porosity. The nanometer scale porosity of these layers can be tuned between 30 and 70%, leading to specific areas of more than 200 m2/g (as measured by BET analysis). The layers are deposited in a pilot roll-to-roll PECVD deposition system, in which we can handle foils with a width up to 30 cm. The linear plasma sources, however, can be easily extended to a width of more than 1 meter, offering perspectives to cost-effective high throughput mass production of the silicon layers. We tested this material both in half cells with Li counter electrode and in full cells with an NMC cathode, with a silicon mass load of approximately 1 mg/cm2. Half cells, charged at 1500 mAh/g at C/5 show no capacity fading and a CE of 99.5% after more than 500 cycles, using a standard electrolyte LiPF6 containing FEC. Bi-layer pouch cells (48 cm2) could be charged/discharged more than 200 cycles at 1000 mAh/gSi without capacity fading but with a CE of about 99.84%. Further improvement of the lifetime is expected through modifications of the electrolyte to decrease first cycle losses of electrolyte due to SEI formation.

Resume : Recently, the beneficial combination of two Li+-storage mechanisms in a single compound, refer to as conversion and alloying materials (CAMs), has been noticed to complement the shortcomings of two mechanisms, which can effectively buffer the large volume change and ensure the electron and ion transport derived from synergistic effects. A new strategy to extend the concept of the present CAMs is to find out the material systems to form the complete solid solution whose end members have the different types of reaction mechanisms with Li+, which can additionally control the ratio of alloying and conversion materials. In addition, since most of the current studies about CAMs are limited to oxides, it is required to switch from oxides to phosphides, which leads to the improved energy density by lowering the Li+ reaction potential and voltage hysteresis. In this study, we suggest a new concept to tailor the electrochemical performance using the solid solution of alloying type MnP and conversion type FeP. The solid solution series Mn1-xFexP (0 < x < 1) were synthesized using high energy milling and their electrochemical properties as an anode for LIBs were investigated, particularly focusing on tunability of working voltage, specific capacity, and cycle retention. The solid solution Mn1-xFexP generates the in-situ nanocomposite where nanocrystalline LixMnyPz and Fe nano-network are embedded in the amorphous Li3P matrix, which can improve capacity retention and high rate stability.

Resume : An intriguing and promising anode material for Li-ion batteries (LIBs), FeNb11O29, is emerging in the last few years. [1] This material garantees the same cell safety of the Lithium titanate (LTO), due to its working potential of 1.6 V, but greater capacity (400 mAh/g) thanks to Nb ions. Furthermore, the rate capability of the Iron niobate is hugely better than LTO, because this shear structure constituted by blocks of octahedra shows a pseudocapacitive behavior. Our work concerns the characterization of both the polymorphs of FeNb11O29 (FNO), which show markedly different electrochemical features notwithstanding great structural similarities. [2] Techniques such as Cyclic Voltammetry, Cyclic Chronopotentiometry and Eletrochemical Impedance Spectroscopy were employed to study the performances of FNO. The structural study which involved powder diffraction with structural refinement as well as magnetic measurements are at the base of the hypothesis for the ?zero-strain? intercalation of Li+ in FNO. [3] Even though the structural stability does not represent an issue for FNO, especially at higher rate capabilities, its doping with other transition metal cations can bring the capacity loss to negligible values at C-rates that can match traditional cathodes more easily. [1] I. Pinus, M. Catti, R. Ruffo, M. M. Salamone, and C. M. Mari, Chem. Mater. 2014, 26, 2203 [2] D. Spada, I. Quinzeni, and M. Bini, Electrochim. Acta 2019, 296, 938 [3] D. Spada et al., Dalt. Trans. 2018, 47, 15816

Resume : Soybeans are regarded as one of the most versatile food sources available due the popularity of their derivative food sources such as soy protein isolate, tofu, soy milk, and miso[1]. Okara is the waste-product as soybeans are processed to make these foods. During the manufacturing of tofu, about 1.2 kg of fresh okara is produced for every 1 kg of soybean processed. This can be used as animal feed or fertilizer but is typically discarded as waste. Huge quantities of this waste are produced worldwide. Japan produces an annual 800,000 tons, Korea produces 310,000 tons, and China 2,800,000 tons[2, 3]. This poses an environmental problem, as the residue is discarded in landfills to rot. This study focuses towards recycling of these okara wastes into cost-effective source of carbon for electrochemical energy storage devices. Okara is first defatted to remove impurities and lipids. The pretreated okara is then activated using NaOH and KOH and studied for its potential use as electrode material. The resulting activated carbon (ACOK) exhibits a high specific surface area thus claiming its potential hold in the supercapacitor market. Further electrochemical studies to evaluate the capacitance, cyclability and performance of this material are being conducted. The energy density can be further improved by introducing an insertion type electrode, Li4Ti5O12 in Li-ion hybrid electrochemical capacitor (Li-HEC) assembly[4, 5]. The combined battery-supercapacitor type reactions in Li-HEC are expected to deliver higher energy densities in comparison to existing supercapacitors. This material caters not only to the pressing issues of waste disposal but also serves as novel and economical source of carbon in the energy storage sector. References: 1. Thayer, A.M.,Degradable plastics generate controversy in solid-waste issues. Chemical & engineering news, 1990. 68(26): p. 7-14. 2. Ohno, A., T. Ano, and M. Shoda, Production of the antifungal peptide antibiotic, iturin by Bacillus subtilis NB22 in solid state fermentation. Journal of Fermentation and Bioengineering, 1993. 75(1): p. 23-27. 3. Ahn, S.H., et al., Environmentally friendly wood preservatives formulated with enzymatic-hydrolyzed okara, copper and/or boron salts. Journal of hazardous materials, 2010. 178(1-3): p. 604-611. 4. Satish, R., et al., Carbon-coated Li3V2 (PO4) 3 as insertion type electrode for lithium-ion hybrid electrochemical capacitors: An evaluation of anode and cathodic performance. Journal of Power Sources, 2015. 281: p. 310-317. 5. Naoi, K., et al., High-rate nano-crystalline Li4Ti5O12 attached on carbon nano-fibers for hybrid supercapacitors. Journal of Power Sources, 2010. 195(18): p. 6250-6254

Resume : Silicon is one of the most promising anodes for lithium-ion (LIB) and sodium-ion (NIB) batteries due to its high theoretical capacity, 3590 mAh/g for Li15Si4[1] and 954 mAh/g for NaSi.[2] Nevertheless, its practical application is hindered by a series of obstacles. For lithium (Li), the access to such high lithiated phases causes extreme volume expansion (310%), resulting in a rapid capacity fade. For sodium (Na), the slow kinetics and the ionic radius restrict the sodiation of c-Si. In an attempt to address these problems, recent attention has been given to the two-dimensional 2D silicon structures, comprising calcium silicide (CaSi2), polysilane (Si6H6) and siloxene (Si6O3H6), due to their potential structural stability during cycling and their facile synthesis through soft-chemical methods. In this work, the lamellar siloxene was obtained via topotactic deintercalation of Ca from CaSi2 and its electrochemical performance was evaluated with Li, Na and K. The results show the versatility of siloxene as anode for LIB, NIB and KIB, with delivered reversible capacities of 2300, 311 and 203 mAh/g for Li, Na and K, respectively. The material exhibits a noticeable structural stability after several cycles, leading to a good capacity retention and coulombic efficiency. The electrochemical mechanism taking place upon cycling is highlighted on the basis of a combination of ex situ characterization techniques; Raman, Infrared, Nuclear Magnetic Resonance and X-Ray photoelectron spectroscopy combined with Scanning and Transmission Electron Microscopy. The observed phenomena cannot be explained merely by a silicon alloying mechanism, therefore a possible alkali intercalation alternative has been proposed. Preliminary evidence of this electrochemical mechanism can be found in the siloxene structural integrity after several cycles followed by SEM and TEM, the absence of the diffraction peaks from NaSi/Li15Si4 (both crystalline and proper from the alloying mechanism) by XRD, and the lack of their respective Raman vibration bands, [3,4] at the end of the discharge. By Raman spectroscopy it was possible to observe a reversible shift of the main Si-plane vibration band for the discharged and charged siloxene, accompanied by a loss of the ?OH and Si-H vibrations observed in the pristine siloxene. Undoubtedly, this last one is likely related to a change in the bond nature of the Si-planes, probably an exchange between ?OH and ?H with Li/Na/K is favored. In fact, the intercalation of Na/Li/K into a layered Si-based materials has been theoretically predicted for a single layer of siloxene (silicene), with no experimental record. The calculations foresee a high coverage of the silicene with alkali ions like Na, Li and K due to the nature of their interactions. The full sodiated/lithiated state of silicene corresponds to X1Si1 (X=Li/Na), the predicted binding energies and diffusion barriers indicate that their intercalation is achievable without the kinetic limitations (higher diffusion coefficient for silicene), structure degradation and volume expansion of bulk Si. [5?9] Complimentary information obtained by XPS and NMR is under analysis. The feasibility for alkali intercalation with a high structural stability presents siloxene as a potential anode for LIB, NIB and KIB batteries. Nevertheless, an understanding of the nature of the electrochemical mechanism is vital to develop its maximum performance. To the best of our knowledge, it is the first time that a lamellar Silicon based material shows such high stable capacity likely due to a very limited volume expansion, representing a real breakthrough for the batteries field and particularly for NIB. References [1] M. T. McDowell, S. W. Lee, W. D. Nix, Y. Cui, Adv. Mater. 2013, 25, 4966. [2] C. Y. Chou, M. Lee, G. S. Hwang, J. Phys. Chem. C 2015. [3] B. G. Kliche, M. Schwarz, Angew. Chemie Int. Ed. English 1987, 26, 349. [4] T. Gruber, D. Thomas, C. Röder, J. Kortus, C. Röder, F. Mertens, J. Kortus, J. Raman Spectrosc. 2013, 44, 934. [5] X. Lin, J. Ni, Phys. Rev. B - Condens. Matter Mater. Phys. 2012, 86, 1. [6] J. Zhuang, X. Xu, G. Peleckis, W. Hao, S. X. Dou, Y. Du, Adv. Mater. 2017, 1606716. [7] H. Oughaddou, H. Enriquez, M. R. Tchalala, H. Yildirim, A. J. Mayne, A. Bendounan, G. Dujardin, M. Ait Ali, A. Kara, Prog. Surf. Sci. 2015, 90, 46. [8] B. Mortazavi, A. Dianat, G. Cuniberti, T. Rabczuk, Electrochim. Acta 2016, 213, 865. [9] V. V Kulish, O. I. Malyi, M.-F. Ng, Z. Chen, S. Manzhos, P. Wu, Phys. Chem. Chem. Phys. 2014, 16, 4260.

Resume : Replacing lithiun with more abundant alkali metals, sodium and potassium, should act to decrease and stabilise the production cost of rechargeable batteries [1]. Though this step to more sustainable "beyond-Li" materials will almost certainly be accompanied by a performance hit, these technologies could find applications at the grid level, where they can be used to smooth out the intermittent electricity supply from renewable energy sources. One hurdle to overcome for Na- and K-ion batteries is the poor performance and capacity of carbonaceous anodes relative to those used in Li batteries. Alloying or conversion anodes provide an alternative route, provided destructive volume changes and resulting nanoparticle pulverisation can be mitigated [2]. We shall present a computational crystal structure prediction study on the ternary K-Sn-P phase diagram, following recent experimental interest in Sn/P as conversion anodes for K-ion batteries [3, 4]. Using a combination [5] of ab initio random structure searching (AIRSS), data mining and evolutionary approaches, several new stable binary and ternary crystal structures are predicted at the semi-local density-functional theory (DFT) level of theory. High-throughput DFT, phase stability and theoretical electrochemical analysis are performed with the open source Python package matador [6]; the package provides an open database of the results for further exploration and dissemination. With a particular focus on the K-P binary system, some of the uncertainties in DFT are taken into account with the Bayesian Error Estimate approach [7]; this is used specifically to aid interpretation of ambiguous experimental results at the maximum state of charge. Stable ternary phases derived from related materials increase the theoretical capacities of the two stable anode materials, SnP3 and Sn4P3, 31% and 19% respectively, with the novel ternary phases providing a route to minimise volume expansion. [1] C. Vaalma, D. Buchholz, M. Weil, S. Passerini, Nat. Rev. Mater. 2018, 3, 18013. [2] H. Kim, J. C. Kim, M. Bianchini, D. H. Seo, J. Rodriguez-Garcia, G. Ceder, Adv. Energy Mater. 2018, 8, 1702384. [3] W. Zhang, J. Mao, S. Li, Z. Chen, Z. Guo, J. Am. Chem. Soc. 2017, 139, 3316?3319. [4] I. Sultana, M. M. Rahman, Y. Chen, A. M. Glushenkov, Adv. Funct. Mater. 2017, 1703857, 1703857. [5] L. E. Marbella, M. L. Evans et al., J. Am. Chem. Soc., 2018, 140 (25) [6] Python package: matador https://matador-db.readthedocs.io [7] J. J. Mortensen et al., Phys. Rev. Lett. 95, 216401 (2005)