Battery and energy storage devices

Resume : Among the oxide ceramic super lithium ion conductors, garnet-type Li7La3Zr2O12 (LLZO) has recently attracted much attention because of its relatively high ionic conductivity at room temperature (>10-4 S cm–1), negligible electronic conductivity and absence of harmful decomposition products upon contact with atmospheric moisture. Recent efforts have been dedicated to the formulation of composite hybrid polymer electrolytes (CPEs), where the ceramic material is embedded in a polymeric matrix. CPEs are stiff while preserving flexibility, are easily processed, and can be conceived to attain improved ionic conductivity and interfacial contact with the electrodes [1]. Here, a polymer based matrix containing poly(ethylene oxide) (PEO), lithium bis (trifluoromethylsulphonyl)imide (LiTFSI), tetra(ethylene glycol dimethyl ether) (G4) and a photoinitiator was added with LLZO particles, thoroughly mixed, formed into a film and crosslinked under UV radiation to obtain a composite hybrid electrolyte [2]. This easy procedure allows obtaining self-standing CPEs with desirable properties of flexibility, shape retention upon thermal stress, improved interfacial contact with the electrodes and ionic conductivity suitable for practical application. Lab-scale lithium metal cells assembled with the CPEs and LiFePO4 cathodes demonstrated specific capacities up to 125 mAh g-1 at 1C rate and could work for hundreds of cycles at ambient temperature. [1] C.K. Chan, T. Yang, J.M. Weller, Electrochim. Acta 253 (2017) 268. [2] L. Porcarelli, C. Gerbaldi, F. Bella, J.R. Nair, Sci. Rep. 6 (2016) 19892.

Resume : The increasing trend of replacing traditional fossil fuels by renewable energy sources in the last 5 years leads to a more sustainable energy supply. However, the positive development is also connected with new challenges. In particular the volatile energy generation and the fluctuating consumption causes imbalances in the power grid. Furthermore, the trading interactions on the electricity exchange market result in frequency deviations. To ensure a stable energy supply robust balancing systems are necessary. This challenging issue can be solved by the integration of battery storage systems (BSS). Based on this motivation the M5BAT project was established. Within this project, a 5 MW and 5 MWh battery storage system was built. The system is composed of five different battery technologies like valve-regulated lead acid, vented lead acid and different lithium-ion technologies (LMO, LTO, and LFP). The setup consists of ten strings, which can be operated independently from each other. One of the aims of the project is the investigation what kind of battery type or which combinations of batteries can be used in an economical way. This will be analyzed for different marketing strategies. Within this context frequency control reserve (FCR) market has a great profitable potential in Germany. In order to ensure a holistic understanding and to derive a resilient evaluation of the BSS, it was operated with 2 MW in the frequency control market. The trading of the FCR takes place on the electricity exchange market according to the “pay-as-bid” approach and with a one-week timeline. The operation is controlled by a sophisticated and intelligent energy management system (EMS). The EMS assumes the function to allocate the requested performance to each string. Within the first part of the paper, the strategy for the power distribution among each string and their influence on the efficiency will be explained and evaluated. Thereby, not only the EMS has a high influence on an economical operation but also the converter settings and dimensions. The effects and their impact will be discussed in detail. For this analysis, the energy throughput for each trading week will be determined with regards to the degrees of freedom (DOF). Based on the real operating BSS the savings can be reliably evaluated. Besides this, another very important part of high impact on the profitability is the technical building equipment (TBE) like air conditioning and ventilation. In the last part of the paper, the setup, the mode of operation and the resulting power consumption will be presented. From this holistic consideration of the BSS operation strategies and the FCR market, the overall losses and saving potentials will be determined. Within this contribution, the possibilities, as well as further challenges for the operation of a storage system with different battery technologies, are discussed in detail. Moreover, from the comprehensive results guidelines for the design and a sustainable commercialization strategy are derived.

Resume : Wearable electronics is emerging as a new and promising field that may revolutionize our life in the near future, and it is currently limited by finding matching power systems with high energy density, good flexibility and high stretchability.[1-4] Among them, stretchable fiber-shaped supercapacitors (SFSSs) are considered as one of the most promising candidates as they can be easily realized by winding fiber electrode on elastomeric substrate or assembling fiber electrodes into a helical structure.[5, 6] However, on one hand, it remains challenging to achieve both high energy density and high stretchabilities based on the available technologies. Herein, an all-in-one fiber electrode combining the function of traditional metal wire and energy storage has been designed and synthesized to solve the above problem. A crystalline conductive polymer (CP) fiber that displayed combined high conductivity, flexibility, specific capacitance and wide electrochemical window was discovered to simultaneously realize high energy storage and serve as conducting wire. The designed fiber material from poly(3,4-ethylenedioxythiophene) (PEDOT):poly(styrene sulfonate) (PSS) after treatment by sulfuric acid (denoted as PEDOT-S:PSS) showed high tensile strength of 112 MPa and high electrical conductivity of 1731 S cm-1 due to the structure rearrangement and ordered crystallized structure. The resulting symmetric SFSSs achieved a wide potential window of 1.6 V, specific capacitance of 93.1 mF cm-2 (or 74.5 F cm-3) at 50 µA cm-2 and high energy density of up to 33.2 µW h cm-2 (26.4 mW h cm-3) based on single fiber electrode. To the best of our knowledge, it represents the highest energy density in the available FSSs. They can be repeatedly stretched by 800%, and the specific capacitance can be well maintained after stretching for 200 cycles and bending for 2000 cycles. [1] J. Bae, M. K. Song, Y. J. Park, J. M. Kim, M. Liu, Z. L. Wang, Angew. Chem. Int. Ed. 2011, 50, 1683. [2] X. Wang, K. Jiang, G. Shen, Mater. Today 2015, 18, 265. [3] W. Weng, S. He, X. Sun, H. Peng, Angew. Chem. Int. Ed. 2016, 55, 6140. [4] W. Zeng, L. Shu, Q. Li, S. Chen, F. Wang, X. M. Tao, Adv. Mater. 2014, 26, 5310. [5] Z. Yang, J. Deng, X. Chen, J. Ren, H. Peng, Angew. Chem. Int. Ed. 2013, 52, 13453. [6] Y. Shang, C. Wang, X. He, J. Li, Q. Peng, E. Shi, R. Wang, S. Du, A. Cao, Y. Li, Nano Energy 2015, 12, 401.

Resume : Membrane capacitive deionization (MCDI) has become more and more attracting due to its easy operation, high safety, environmental friendliness, energy efficient and cost effectiveness. There exist two different operational modes in traditional MCDI, constant current (CC) and constant voltage (CV) modes. And varieties of parameters have been adopted to investigate the difference of CC and CV operational modes, such as flow rate, cell potential, current density and feed water concentration. Most recently, a new parameter faradaic reaction has been introduced into MCDI system. Unlike traditional physical adsorption by the electrical double layers (EDLs) of the porous materials, the salt ions in water will be intercalated into the crystal structure of the electrode materials with the introducing of faradaic reaction, which means the salt adsorption capacity will not be restricted by the surface area of the porous materials any more. Therefore, in this work, the influence of faradaic material in CC and CV operational modes MCDI upon different choices of electrode materials has been analyzed. The salt removal capacity and charge efficiency have been enhanced under the influence of faradaic reaction. And the energy consumption has been much decreased. Meanwhile, faradaic reaction has been proven to be more incline to happen under CC operational mode MCDI, indicating its advantage over CV operational mode with certain choice of electrode materials.

Resume : The global effort to improve the lifetime, power densities and energy efficiency of energy storage and conversion technologies, such as batteries, fuel cells, and supercapacitors, has become dramatically more extensive with increased demand from portable electronics and the electrification of transportation. Currently, lithium- oxygen (Li-O2) batteries have been considered as the most promising next-generation electrochemical energy storage technology to meet near future transportation application. Contrary to the traditional Li-ion batteries, Li-O2 batteries abandon the intercalation and conversion reaction electrodes and Li ions react directly with O2 from the air in a porous electrode. This unique battery chemistry and electrode architecture induce an extremely large theoretical specific energy ~ 3600 W h kg-1, which is considered capable of providing enough energy storage capability for electric vehicles to drive more than 500 miles (per charge). In this work, several promising efficient catalysts for Li-O2 batteries have been synthesized as novel cathode catalysts and their electrochemical performance have been investigated in the viewpoint of their electrical conductivity and structural properties

Resume : The complexity of the solid electrolyte interphase (SEI) in lithium-ion batteries with graphitic electrodes, has triggered extensive deal of research due to its crucial properties for the long life of the battery. The SEI layer is composed of organic and inorganic species and results from the electrolyte decomposition on the electrode-electrolyte interface upon the first cycling of the battery. A stable SEI layer is crucial to maintaining the chemical and mechanical stability of the electrode, and the electrochemical stability of the electrolyte in order to prevent irreversible capacity loss. This work uses computational crystal structure prediction genetic evolutionary algorithm to simulate the nucleation, the growth and the aggregation of the inorganic products forming the SEI mosaic film. In-depth investigation of the growth mechanisms of LiF and Li2CO3 starting from the first nucleation seeds is undertaken. The nearshore SEI layer cluster aggregation growth mode at the graphite surface is shown to be strongly dependent on its degree of lithiation and surface termination states.  Acknowledgments: This work is sponsored by the Qatar Environment and Energy Research Institute (FE). Computational resources have been provided by the research computing team at Texas A&M University at Qatar. This work is supported by the Qatar National Research Fund (QNRF) through the National Priorities Research Program (NPRP7-162-2-077)

Resume : Graphene-based materials are emerging as smart alternatives to activated carbon used in commercial supercapacitor. Here, we present chemical reduction of graphene oxide (GO) in aqueous medium by an unconventional mild reducing agent (FeCl2/HCl) where self-assembled reduced graphene oxide (rGO) is isolated and the reducing agent is recycled upon simple treatment of the filtrate with HCl. The fabricated all-solid-state supercapacitor of as-synthesized rGO exhibited significantly higher specific capacitance (171 F/g at 1.1 A/g), remarkable cycling stability (>80% retention of capacitance beyond 100,000 continued cycles), and flexibility (>500 bending cycles), which is comparatively much better than those of rGO derived from conventional reducing agents like NaBH4 and N2H4. Use of organic electrolyte further boosted the supercapacitor performance (282 F/g at 1.8 A/g) of rGO. This work opens up new possibilities for the production of rGO on an industrial scale satisfying the needs of high-performance energy-storage devices.

Resume : In January 2017, Samsung announced the reason why the Note 7 explodes and losses of more than 5 billion US dollar. According to their explanations, it was caused by the internal short circuit problem in the lithium ion battery. Currently, there is no effectively solution for eliminating the internal short circuit problem owing to the sudden accident. In this research, a new technology has been developed, which can be used to terminate the thermal runaway and promise the safety performance of lithium ion battery. High voltage Li-excess and Ni-rich layer-type cathode material are employed and combined with this safety electrode additive for investigation. In terms of the results, the new technology LIVING@ additive significantly enhances the cycle performance at 60oC and high voltage. In addition, the following figures illustrated that the battery containing LIVING@ technology is stable and passed the nail penetration test. On the other hand, the battery without LIVING@ cannot be used when the short problem is taking place. The LIVING@ contains self-polymerized hyper branch structure in order to insulate the directly contact between anode and cathode. This electrode additive not only provides high thermal stability on electrochemical reaction, but the columbic efficiency of charge-discharge is also enhanced.

Resume : Oxygen reduction reaction is a complex reaction that is involved in energy conversion applications such as air-based batteries and fuel cells. The high price of Pt makes necessary the development of highly durable electrocatalysts. In this sense, transition metal oxides mixtures have shown remarkable results in both, air-batteries and fuel cells. In this work, a TMOM based on Ni and Mo with a small content of Tungstic acid (WA) as additive (denoted as MoNiW) was synthesized following a polyol route using polyvinylpyrrolidone, ethylene glycol and ascorbic acid as the stabilizer, reaction media/reducing agent and co-reducing agent, respectively. A Mo-Ni TMOM without WA was synthesized as control, and according with TEM micrographs it presented particle sizes ranging from 40 to 70 nm. The addition of WA to the MoNiW TMOM decreased the particle size to 19.7±0.5 nm, and promoted the formation of particles with defined shapes regardless particle size: semispherical and cubic-like shapes, being the nanocubes indexed to NiO. Evaluation of the oxygen reduction reaction in alkaline medium (0.1 M KOH) was carried using a rotating disk electrode. At 1600 rpm, the MoNiW catalyst exhibited a half-wave potential of 0.68 V vs. RHE with a current density of 3.2 mA cm-2, and in comparison, with commercial Pt/C, the MoNiW catalyst has a overpotential of only 170 mV. Therefore, herein we demonstrated the high activity of a MoNiW electrocatalyst for ORR in alkaline medium as a promising material for energy conversion applications.

Resume : With increasing demands for high-energy density, lithium sulfur batteries are becoming an appealing technology. As a matter of fact, in addition to a high theoretical capacity of 1672 mA h g-1, S is also lightweight, cheap, widely available as well as non-toxic and safe. All these factors combined justify its appeal for large-scale applications. Up to now, the main explanation for not reaching the theoretical values is the unfavorable behavior of polysulfides (PS) formed during cathode reaction. During the discharge reaction, elemental S is reduced to form PS. During the following charging process, the reaction should be completely reversed, however, the good solubility of most PS in most liquid electrolytes induces loss of active material and hence rapid capacity decay upon cycling. Moreover, direct reaction of those PS onto metallic Li anode forms a passivating layer and alters anode surface (dendrite formation). A promising approach to solve these issues is the use of polymer membranes in different positions inside the cell. As a matter of fact, the versatility of polymer matrices combined to a very wide range of compatible additives allows to unite the advantages of different material classes, thus producing a solution to nearly every problem encountered. For instance, a polymer/ceramic composite membrane, based on PVDF-HFP, sandwiched between cathode and separator, can actively confine the PS on cathode surface, limiting the shuttle effect and greatly expanding cycle life. Another type of membrane, methacrylate-based, containing different additives and photo-reticulated directly onto the metallic Li anode to obtain a greater contact, can reduce to a minimum dendrite formation.

Resume : Intermetallic (Si, Sn, Sb etc.) electrodes offer significantly higher volumetric and gravimetric energy density compared to the widely used graphite-based electrodes, which make them promising candidates for next generation Li-ion cells for transportation applications. [1] However, numerous studies have demonstrated that the inherently non-passivating behavior of intermetallic electrodes in standard organic carbonate-based Li-ion electrolytes [2] is aggravated by significant volume changes during the charging and discharging processes. Mechanical stresses from volume change lead to particle decrepitation, resulting in electronic isolation of particles, loss of mechanical integrity of composite electrodes and interfacial instability. Particle factures expose fresh electrode surface to the electrolyte during cycling, leading to formation of a thick film of electrolyte reduction products, causing impedance rise, capacity loss and lithium inventory shift in the cell. [3] The solid electrolyte interphase (SEI) layer, which forms at the electrode/electrolyte interface during the initial charge/discharge cycles, is the key component that determines the long-term stability and cycling behavior of negative Li-ion battery electrodes. [4-6] Electrolyte reduction and SEI layer formation on these electrodes usually take place at potentials below 1.8V vs. Li/Li+ and accompany the formation of Li-Me phases, the so-called “Me-Li alloying” process at E <0.8 V vs. Li/Li+. The exact mechanism of the SEI formation processes on Si, Sn, Sb and their alloys with lithium, the SEI composition and the effect on the electrode electrochemical cycling performance is not well understood. Interestingly, model studies on Sn single crystal electrodes in organic carbonate electrolytes revealed a strong correlation between the crystal surface orientation and the SEI composition. [7,8] A similar study of the composition of the SEI on a silicon monocrystal electrode showed strong effects of different SEI formation protocols, presence/absence of intrinsic SiO2, electrolyte composition and impurities e.g., HF. On the other hand, SEI-forming electrolyte additives such as vinylene carbonate (VC) and fluoroethylene carbonate (FEC) are known to alter the composition and properties of the SEI on Si and improve the electrode electrochemical performance. This study involves rigorous diagnostic studies of tin, silicon, Si-based alloys, and composite Si-based model electrodes to determine and understand the key thermodynamic and kinetic parameters, which enable their function and operation in Li-ion battery systems. Advanced diagnostic tools are used to gain fundamental insight into mechanism of intermatallic-based electrodes failure. An emphasis is placed on in situ methods that use multiple techniques at the same time e.g., imaging with spectroscopy. The diagnostic experimental strategies involve evaluations of model silicon and other intermetallic model composite electrodes as well as studies of the properties of the individual components and their interfaces in a carefully designed and well defined experimental systems. The interfacial instability of the electrolyte and the uncertainty associated with the formation of a stable solid electrolyte interphase (SEI) are the key problems being addressed. Acknowledgements This work was supported by the Assistant Secretary for Energy Efficiency and Renewable Energy, Office of Vehicle Technologies of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231, under the Applied Battery Research for Transportation (ABR) Program and Award Number DE-EE0006443.

Resume : Novel non-aqueous organic electrolytes with wide electrochemical window and high ionic conductivity have great potential for rechargeable lithium-ion batteries. Herein, we report the synthesis and performance of three ionic salts such as lithium carbonylbis(fluorosulfonyl)amide, lithium (1,3-phenylenedisulfonyl)bis(sulfamoyl fluoride), and lithium ((4-flurophenyl)sulfonyl)amide, respectively. The electrolyte salts with two lithium shows better performances such as high ionic conductivity, cyclic, and electrochemical stability compared to mono-valent salt ((lithium ((4-flurophenyl)sulfonyl)amide)) due to the high concentration of the lithium ion in the solution and formation of stable solid electrolyte interface (SEI) layer on the electrode surface. Full Li-ion batteries based on these electrolytes (1 M electrolyte solution in ethylene carbonate/dimethyl sulfoxide solvent) using LiCoO2 cathode and graphite anode will exhibit good specific discharge capacity in conjunction with conventional organic solvent-based electrolytes. The structures of the resultant electrolytes were confirmed by 1H-NMR and 19F NMR spectroscopy. The properties and performances of the resultant electrolytes were investigated by differential scanning calorimetry (DSC), electrochemical impedance spectroscopy (EIS), cyclic and linear sweep voltammetry (CV and LSV).

Resume : This communication delas with the evaluation of a Fe-air battery cell for application as electric energy storage device at intermediate temperature (500-700 °C). Zhao et al. suggested an architecture similar to a reversible SOFC/SOEC cell combined with an active Fe-electrode placed in the same closed fuel electrode chamber [1]. The operation of such cell consisted in a combination of a reversible SOFC/SOEC cell with the redox cycle of Fe-Fe2O3 and requires a recirculation of H2/H2O. The net electromotive force is given by the Fe-redox couple. Although they achieved good performance, such architecture is affected by cells stacking constraints. In this work we explored the feasibility of a simply architecture consisted of a sandwich based on Fe2O3-CGO as Fe electrode, La0.8Sr0.2Ga0.8Mg0.2O3 (LSGM) or Gd0.1Ce0.9O2 as supporting electrolyte and La0.6Sr0.4Fe0.8Co0.2O3 (LSFCO) as O2 electrode. Such type of cell had an architecture similar to a SOFC cell. However, such cell did not require any gas recirculation, whereas no internal manifold of gas is expected in a stack of these cells. The cell battery based on CGO showed a significant propensity to the spontaneous discharge due to low electrical stability of the Ce(IV) and due to its large capability for the oxygen storage. On the other hand, LSGM based cell battery showed at 650 °C a stable cycling behaviour (over 100 cycles) quite high current capacity (450 mAh g-1), energy density (400 mWh g-1), and voltage efficiency (75%).

Resume : The exploitation of a high-efficient, low-cost and stable non-noble metal-based catalyst with oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) simultaneously, as air electrode material for rechargeable zinc-air battery is significantly crucial. Meanwhile, the compressible flexibility of a battery is the prerequisite of wearable or/and portable electronics. Herein, we present a strategy via single-site dispersing Fe-Nx species on a two dimensional (2D) highly-graphitic porous nitrogen-doped carbon layer to implement superior catalytic activity toward ORR/OER (with a half-wave potential of 0.86 V for ORR and an over-potential of 390 mV at 10 mA·cm-2 for OER) in alkaline medium. Furthermore, an elastic polyacrylamide (PAM) hydrogel based electrolyte with the capability to remain great elasticity even under highly corrosive alkaline environment, is utilized to develop a solid-state compressible and rechargeable zinc-air battery. The creatively developed battery performs a low charge-discharge voltage gap (0.78 V at 5 mA·cm-2) and large power density (118 mW·cm-2). It could be compressed up to 54% strain and bended up to 90o without charge/discharge performance and output power degradation. Our results reveal that single-site dispersion of catalytic active sites on porous support for bi-functional oxygen catalyst as cathode integrating specially designed elastic electrolyte are feasible strategies for fabricating efficient compressible and rechargeable zinc-air batteries, which could enlighten the design and development of other functional electronic devices.

Resume : Magnesium batteries are promising candidates as an alternative to Li-ion batteries thanks to its high abundance, low cost, safety and theoretical capacity (2.2Ah/g -3.8Ah/cm3). Nonetheless metallic Mg reacts with conventional electrolytes to form a barrier on its surface, rendering cation exchange impossible, and thus dramatically limiting reversible stripping/deposition of Mg. An interesting alternative for the development of Mg batteries is to replace Mg metal with another negative electrode, compatible with conventional electrolytes. Recently, it has been showed that p-block elements (Sn, Sb, In, Pb, Bi) can electrochemically alloy with Mg and possess adequate stability in conventional electrolytes [1]. To evaluate a possible synergy effect between different elements as already observed for SnSb [2] and BiSb [3], we synthetized InSb powder through high energy ball-milling. This alloy may be of great interest as it would combine the high theoretical capacity of Sb (660mAh/g) and the lowest working potential reported for In in a Mg battery. Here we demonstrate that the combination of In and Sb has a beneficial effect on the reaction mechanisms and enables higher specific capacities compared to In-based electrodes. The characterization of the peculiar electrochemical behavior of InSb will also be described in details. 1. Murgia et al., Electrochem. Commun. 60, 56 (2015) 2. Parent et al., Nano Lett. 15, 1177 (2015) 3. Arthur et al., Electrochem. Commun. 16, 103 (2012)

Resume : Elemental phosphorous is emerging as one of the most intriguing anode materials for Li, Na, and K rechargeable batteries due to its specific capacity of 2596 mAhg-1. At the same time, the performances obtained from different tests are far from the theoretical values (~600-1000 mAhg-1). Moreover, no clear indications about the phosphorous form most suitable for electrochemical applications is emerged until now. Elemental phosphorous exists as different allotropes, including white phosphorous, WP, red phosphorous, RP, and black phosphorous, BP. Orthorhombic BP, the most stable polymorph, presents a 2D structure, making it particularly intriguing as anode material. The preparation of ortho-BP is thus a central issue in development of anodes based on elemental P. Among the variety of complex synthesis approaches, high energy ball milling, HEBM, starting from the commercially available RP appears to be the most convenient. Even if HEBM is one of the most diffuse preparation method and several experimental procedures have been proposed, no systematic exploration of the synthesis parameters has been tackled to date. Here, we report on a detailed investigation of the role of the synthesis conditions, together with the characterization of the obtained products. A careful spectroscopic investigation coupled with multivariate analysis allowed us to state how the different HEBM parameters (speed, filling factor, duration) can be tuned to control the nature of the final products.

Resume : The aim of this research is to conduct X-ray and e beam characterization techniques on lithium-ion battery materials for the improvement of battery performance. The key characterization techniques employed are the synchrotron X-ray Absorption Spectroscopy (XAS) combined with X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) to obtain a more holistic approach to understanding material properties. This research effort provides additional battery characterization knowledge that promotes the development of new cathode, anode, electrolyte and separator materials for batteries, hence, leading to better and more efficient battery performance. Both ex-situ and in-situ synchrotron experiments were performed on LiFePO4, one of the most common cathode material, from different commercial sources, and their structural analysis were conducted using Athena/Artemis software. This analysis technique was then further extended to study other cathode materials like LiMnxFe(1-x)PO4 and even some sulphate systems like Li2Mn(SO4)2 and Li2Co0.5Mn0.5(SO4)2. XAS data were collected for the all the possible edges, Fe, Mn, P and S K-edge. Analysis of EXAFS data for all these edges is demonstrated here, with emphasis given mostly on the phosphate systems since very little information is available about the P K-edge from previous studies. XANES studies of all these edges also give information about the oxidation state and electronic configuration around the absorbing atom. Finite Difference Method for Near Edge Structure (FDMNES) simulations was also conducted for various phosphate model compounds and compared with the experimental XANES data to understand mainly the pre-edge structural information of the absorbing atoms.

Resume : Spinel nickel manganite-carbon nanofibers composites (NiMn2O4/CNF) are prepared by electrospinning method and investigated as electrode materials for vanadium redox flow battery (VRFB). The presence of spinel NiMn2O4 structure as well as the formation of graphitic carbon are detected by X-ray diffraction (XRD). A complete covering of carbon nanofibers by NiMn2O4 nanoparticles is evident by scanning electron microscope (SEM). Cyclic voltammetry (CV) measurements recorded high electrochemical performance in terms of peak to peak separation (E= 0,1 V). Charge-discharge tests carried out at high current density value (150 mA/cm2) show an energy efficiency value EE > 70 %. The catalytic performance obtained by NiMn2O4/CNF can be ascribed to the higher oxygen species content as well as the synergetic effect of the more graphitic carbon and the structural defects within the spinel NiMn2O4 structure [1]. In addiction, the nickel inclusion in manganese oxides (MnxOy) promotes the formation of spinel NiMn2O4 phase with a high surface area (193 m2/g) and high electrical conductivity [2]. These latter properties are probably the responsible for an increase of the NiMn2O4/CNF kinetic reaction at the electrode/electrolyte interface. References: [1] A. Di Blasi, C. Busacca, O. Di Blasi, N. Briguglio, G. Squadrito, V. Antonucci, Applied Energy 190 (2017) 165–171. [2] P. Ahuja, S. K. Ujjain, R. K. Sharma*, G. Singh, RSC Advances 4 (2014) 57192-57199.

Resume : The present work evaluates NiFe2O4 3D hollow spheres as low-cost transition material with high catalytic activity towards water splitting using a microfluidic electrolysis system. The H2 production was evaluated by cronoamperometry at different flow rates at a voltage of 1.6V using 1M KOH as the electrolyte. The main feature of microfluidic electrolysis system was the porous electrodes that allow to increase the available surface area. The results showed that the NiFe2O4 3D hollow spheres maintain 2.5 mA during the experimental time, with a very similar catalytic activity to electrocatalytic materials commonly used such as IrO2 and Pt, consequently NiFe2O4 3D hollow spheres has a great potential candidates as Pt-free material for H2 production. Keywords: water splitting, microfluidic electrolysis system, Pt-free materials

Resume : Lithium batteries (LiBs) are the most used rechargeable batteries for portable electronic devices. The development of flexible, safe, cheap and efficient batteries has become a necessity in our modern society. This implies the development of new chemistries for the electrolyte and the active electrode materials. For electrochemical energy storage technologies, the polymeric materials are searched due to their broad range of properties such as adjustable mechanical properties, sustainability or ionic/electrical conductivity. Redox polymer is a class of polymers based from groups which change redox form (loss and gain of electrons) in contact with electrical potential stimuli. One of the best known is the poly(2,2,6,6-tetramethylpiperidinyloxy-4-yl methacrylate) (PTMA) which display ultra-fast electron-transfer process (10-1 cm/s), good theoretical specific capacity (111mAh/g) and a reversible redox process (3.6V vs Li/Li ). Fluorinated copolymer bearing cyclic carbonate pendant groups, such as poly(vinylidene fluoride-co-(2-oxo-1,3-dioxolan-4-yl)methyl 2-(trifluoromethyl)acrylate) random copolymer, was studied as solid polymer electrolytes. The added lithium salt was dissolved in the poly(VDF-co-MAF-CyCB) amorphous phase and allowed the formation of an ionic conducting phase exhibiting ionic conductivity values as high as 2x10-4 S/cm at room temperature for an optimum cyCB/Li molar ratio of 5. This material displays good mechanical properties (up to 107 at 102 rad/s) and lithium ions transference numbers (0.68 at 40 °C). Here we will discuss about the use of PTMA as cathode active material and the poly(VDF-co-MAF-CyCB) copolymer as promising solid polymer electrolytes in energy storage devices. [1] F. Boujioui, O. Bertrand, B. Ernould, J. Brassinne, T. Janoschka, U. S. Schubert, A. Vlad and J.-F. Gohy, Polym. Chem., 2017, 8, 441-450. [2] F. Boujioui, F. Zhuge, H. Damerow, M. Wehbi, B. Améduri and J.-F. Gohy, J. Mater. Chem. A, 2018,6, 8514-8522

Resume : The next generation of Li-ion rechargeable batteries is contingent on the development of new cathode materials with a greater capacity to store charge. Current state-of-the-art materials can deliver in the region of 180-200 mAh g-1 of charge storage capacity, however these materials are fundamentally limited by the amount of redox active transition metal present. One possible route to unlock significantly extended capacities is to invoke charge compensation using oxygen as well as the transition metal of lithium transition metal oxides. To harness the opportunities such materials offer, it is necessary to understand the nature of O-redox processes in the solid state and the factors that control them. O-redox in 3d transition metal oxides will be discussed, leading to a new high capacity manganese-based cathode that utilizes the full capacity of the Mn as well as charge storage on oxygen.

Resume : The use of lithium-ion batteries (LIBs) is expected to expand further due to the increased use of renewable energy, such as solar and wind. LIBs utilized in stationary applications enable reliable supply of electricity stored in the batteries, while LIBs used in electric vehicles (EVs) can be charged with the renewable energy sources installed in private households. The end-of-life (EOL) for LIBs in EVs is conventionally determined by 80% state of health (SOH) and for stationary applications - 60% SOH. Before the EOL is reached, the number of obtained full cycles can be increased by considering the degradation stress factors. The degradation stress factors are all the operating practices and conditions that accelerate the battery degradation. Those include high current, high cycle depth, high average state of charge (SOC) or extreme temperatures. When using the LIBs, the reduction of the environmental impact primarily occurs through avoided use of conventional vehicles with internal combustion engines or avoided consumption of electricity from grid. In such a way, a higher reduction of the environmental impact from LIBs is expected due to increased number of full cycles facilitated by consideration of the stress factors and cautious management of batteries. Such a reduction will help to reduce the cradle-to-grave environmental impact of the LIBs, which can be assessed using the life cycle assessment (LCA) methodology. This study combines the technical aspects of LIBs to LCA.

Resume : Lithium ion batteries are key in the modern society as they are present in many energy storage devices and have a promissing future perspectives in the field of electric cars and energy accumulators from renewable sources. Herein, we present results from charge and discharge cycles on batteries with controlled conditions. The ciclability of comertial lithium-polymer “pouch” batteries, has been studied under different charge/discharge rate and temperatures. The relationship between the state of charge and the cell voltage has been obtained, and the degradation of the cells energy capacity after a number of cycles has been measured. Furthermore, the experimental results have been compared with simulations based on Newman’s model for Lithium Ion Batteries, carried out using Comsol Multiphysics software. The results show the correlation between temperature, C-rate and degradation in lithium ion batteries batteries. It is specially remarcable the decrease of the apparent capacity of batteries at low temperatures, and the increase of the degradation at higher temperatures. These results are essential for the design of control mechanisms that can prevent battery failure.

Resume : The electric vehicle industry has known a rapid development in the recent years. Indeed, increasing concerns regarding global warming, such as CO2 emissions, led automakers to implement cleaner technologies in their vehicles. For instance, to be competitive with thermal engine vehicles, a lot of work is carried out to enhance the energy storage systems of the electric vehicles (EV) in order to improve their autonomy and performance. Thus, it is essential for automakers to understand how driving conditions affect the battery ageing as it results on capacity and power fade. These parameters estimation can be made by using different approaches, from detailed electrochemical equations to mathematical data based models. Yet, none has so far performed enough to obtain a real time battery ageing estimation in EV application. In this work, a semi-empirical approach is presented and aims to model the electro-thermal behavior as well as the ageing of LIB’s. (i) The fatigue approach consists in adding the constraints related to a cycling conditions in order to determine a capacity and power loss [1]. (ii) The entropy profiles [2] will help to find a deeper correlation with the battery state of health and to determine the entropic heat [3]. Indeed, temperature is known to be one of the most important factor affecting the LIB ageing. Our model will help to understand the temperature dynamics inside the cells and will be validated with several temperature measuring tools such as thermocouples and Electrochemical Impedance Spectroscopy technique [4]. The robustness of this model relies on the mixing of several parameters (capacity, resistance and entropy profiles) coupled to a thermal model to estimate the battery ageing as well as to understand its electro-thermal performance. Our main goal is to optimize the EV life of the battery throughout a good knowledge of the cycling conditions impact on its ageing. [1] Q. Badey “ Etude des mécanismes et modélisation du vieillissement des batteries lithium-ion dans le cadre d’un usage automobile“. 2012. [2] P j. Osswald et al. “Fast and accurate measurement of entropy profiles of commercial lithium-ion cell“. Electrochimica Acta, vol. 177, 2015, pp.270-276. [3] D. Bernardi, E. Pawlikowski, J. Newman, “A General Energy Balance for Battery Systems”, Journal of the Electrochemical Society (ECS), vol. 132, no. 1, Dec. 1984, pp. 5-121. [4] R. Srinivasan, “Monitoring dynamic thermal behavior of the carbon anode in lithium-ion cell using a four-probe technique“, Journal of Power Sources, vol. 198, 2012, pp. 351-358.

Resume : Transition metal layered oxides are attractive cathode materials due to their ease of synthesis, good tap density and high energy density. In this work, Na0.95Ni0.32Ti0.32Mg0.16Mn0.21O2 is selected as the cathode active material and full cells are assembled using hard carbon as the anode component. Reversible capacities of ca. 140 mAh g-1 and 200 mAh g-1 are obtained at C/10 respectively for the cathode and the anode in half cell configuration using electrode formulations which are suitable for lab-scale studies. With the aim of increasing the electrode loading and therefore the energy density, initial tests have been done by increasing the active material content up to 94 wt. %. In addition, carbon black and binder ratio has been optimized in order to improve the interaction between different elements of the slurry, make a good balance between the adhesion and ion-blocking effect of the PVDF binder, improve the electron conducting effect of the conductive additive and decrease the inactive material content. Optimized cathodes with 88 wt. % of active material content are used for full cell fabrication with balanced anode electrodes. Those cells delivered 190 mAh g-1 and 140 mAh g-1 for the first charge and discharge capacity, respectively, being the average discharge voltage 2.9 V. Cyclability tests show 72% of capacity retention after 100 cycles which make this combination of materials an attractive choice for the development of a sodium-ion battery.

Resume : Nowadays, resilient grids meet growing interest for their capability of supplying critical load even in case of power fault coming from grid disturbance and disasters. To do this, such grids involve redundant apparatus and predictive control schemes. For high value services, unexpected system unavailability is source of economic losses to the providers. Hence, beside the internal energy storage devices, such plants had better to have redundancy of energy sources (e.g. electrical grid and natural gas network) and tailored power flows control strategies still valid even in the case of external energy shortage. In this work, a supply system was developed both matching the requirements (both DC and AC) of the served ICT equipment, and capable of offering grid services as an experimental prosumer site. As fundamental design targets, energy conversion efficiency and cost reduction were addressed by developing a hybrid fuel cell/battery (SOFC/SNC) based prototype, and optimizing the size of each used device. Starting from field tests measurements, the hybrid generator was analyzed in a resilient grid scenario. Then, digital simulations compared different battery management algorithms and assessed the trade-off between battery exploitation and system resiliency against grid or gas network fault. The prototype showed satisfactory performance both for resilient microgrids and applications in which the continuous availability is a critical point (e.g. ICT equipment and data centers).

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 are usually characterized by a low lithium-ion transference number (TLi+ < 0.5) and consequently are more susceptible to polarization phenomena that eventually limit the power density and cycle life of ASSLPBs. 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. Among which, chemical modification such as cross-linking or copolymerization are the main used strategies. In addition, the anion concentration gradient that takes place in conventional dual-ion conductors is one of the factors responsible for low TLi+. The main strategy to overcome this polarization problem is the development of single lithium-ion conducting solid polymer electrolytes (SLIC-SPEs), where the anion is immobilized by different means. In this talk, the physicochemical and electrochemical properties of our recently developed SPEs are presented. In particular, SLIC-SPE comprised of a flexible and highly conductive comb-like polymer grafted with polyether amine oligomer side chains and a polystyrene-based polysalt is conceived so as to decrease the working temperature and to avoid problems related to polarization.

Resume : Composites of e.g. Li7La3Zr2O12 (LLZ) and LiCoO2 (LCO) are used as cathodes in all-solid-state batteries. However, LCO undergoes a volume change of approximately 4% during delithiation. The typical microstructure of a screen printed cathode was reconstructed in 3D with FIB/SEM using an enhanced binarization method and an elastic finite element simulation yielded compressive stresses in the LCO phase up-to 1.0 GPa and tensile stresses in the LLZ phase up-to 1.3 GPa, respectively. These resulting stresses will cause plastic deformation, fatigue and early failure of the cell. Volumetric stress histograms were used to quantify and compare the stress states for free standing cathodes, electrolyte-supported design (50 µm cathode on 400 µm electrolyte) and cathode-supported design (100 µm cathode on 4 µm electrolyte). In any case, the calculated stresses were critical for one of the components. Microstructural features such as pore chord length could be linked to the calculated anisotropic stress state providing hints for a strategy for stress minimisation. A honeycomb LLZ framework with a segmented LCO coating could lower stresses drastically below the yield stress. As the practical viability of such structures is rather difficult, the influence of microstructural parameters of typical screen printed layers like the volume ratio of the two phases, the grain size, and the porosity on the resulting stresses were also investigated using computer-generated microstructures.

Resume : Fuel cell is a device based in electrochemical reactions that convert chemical energy in electrical energy, using a constant source of fuel, unlike in batteries. One of most used fuel cell is Proton Exchange Membrane Fuel Cells (PEMFCs) studied for many applications like automobile and mobile phone. In a PEMFC the fuel is O and H gas. Anode and cathode are immersed in an electrolyte and are separated by a membrane able to transport protons (H ). In anode take place the hydrogen oxidation reaction while at the cathode the oxygen reduction. This latter is a slow kinetic process and it required a catalyst that consists of platinum nanoparticles supported in carbon. This catalyst is subject to degradation implying a reduction of the PEMFC life time. Electrochemical experiments of cyclic voltammetry (CV) are implemented to study the degradation of PEMFC. During cyclic voltammetry the PEMFC is in operando conditions, the potential at the electrodes is so cyclically varied in order induce an aging of the device. The catalyst degradation is monitored on the basis of the cyclic voltammogram, but no clue is given about the nanoscale processes on the catalyst responsible of its degradation. In order to obtain this information, CV experiments have carried in-situ of a transmission electron microscope (TEM). The catalyst degradation during CV can be monitored also by nanoscale images. Mandatory international experimental protocols are related to ex-situ CV. Our work investigates the relationship between ex-situ and in-situ CV of the Pt catalyst. The electron beam increases the aging that can be imparted improving in-situ CV versatility. Such results make in-situ CV experiments more linkable to real scenarios and so interesting for industry.

Resume : Nanometric silicon appears as an interesting candidate to improve the capacity of lithium-ion batteries anodes because its theoretical specific capacity is over 10 times that of current commercial graphite electrodes. A major issue with nanosilicon anodes is the continuous formation of solid electrolyte interphase (SEI) due to the significant volume changes in the material during lithiation-delithiation. Coating the silicon surface with carbon has proved to protect it, as a more stable SEI is obtained. For this purpose, we synthesize core@shell silicon-carbon nanoparticles by using a double-stage laser pyrolysis reactor [1]. This gas-phase technique allows one-step synthesis of a silicon core coated by a carbon shell. The size and the size distribution, as well as the shell’s thickness, can be controlled by the modification of parameters. This wall-less process leads to clean interfaces. In this work the synthesis of carbon coated crystalline nanosilicon (30 nm) with various carbon contents, up to 20 % w/w, will be presented. These Si@C particles present a clear silicon-carbon interface as shown by STEM-EELS. The galvanostatic performance comparison indicates that the coulombic efficiency is improved by a greater carbon content and power rate experiments indicate that an optimum exists. Finally, by using electrochemical impedance spectroscopy (EIS), a comparison of SEI resistances for coated and non-coated particles will be presented. [1] Sourice et al, ACS Appl. Mater. Interfaces 2015

Resume : Lithium-Ion batteries (LIB) are widely used in many types of mobile applications nowadays and the demand will even increase with the wider implementation of electric vehicles and stationary storage systems. Therefore, research and development efforts are directed towards improving both performance and diagnostic methods of LIBs. Recently, the mechanical behavior of the cells started to be investigated more into detail, since it can be correlated to their State-of-Charge (SoC) or, in general, State-of-Health (SoH), and thus becoming an accurate diagnostic method. A significant example would be the volume change during lithiation and de-lithiation processes, which is quite significant at the anode side – i.e. graphite and especially silicon-based materials. Changes in volume are nowadays mainly monitored by dilatometer measurements. This work introduces a promising additional in-situ, non- invasive technique to monitor the mechanical properties of cells. The mechanical frequency-response-function (FRF), which is well-known in several applications such as civil engineering, mechanical engineering and structural dynamics, is here applied to LIBs. All investigations were carried out on two types of commercial pouch cells with NMC as cathode and graphite as anode. One of the cell is high-energy optimized, while the other one is optimized for lifetime. Except for their thickness, the cells exhibit the same dimensions, which allows for a good comparison. The cells are excited by means of an electrodynamic shaker, and their response is measured by using an impedance head. It is shown that the FRF is able to determine relevant mechanical parameters of the cell such as damping and stiffness. This data then can be correlated with different operational parameters and conditions of the cell – e.g. SoC and cell temperature. As only low forces of a few Newton are needed, the method has high potential for miniaturization and for cost reduction. To validate the method, dilatometry measurements are performed on full cells, too. In order to better evaluate these results, also the individual electrodes – both anode and cathode – from the commercial cells were tested separately in half-cells (vs. lithium metal) by means of cyclic voltammetry and dilatometry. For this purpose, cells were dismantled under an inert gas atmosphere and all components were removed and evaluated. In addition to the electrochemical characterization, other electrode properties were investigated by means of several characterization techniques – e.g. XRD, SEM, BET and thermal analysis. The work will present all these activities and show the potential but also the boundaries of FRF as method for cell diagnostics.

Resume : The approach to reversibly control the magnetic properties of a transition metal compound could be recently shown using a concept derived from intercalation based lithium ion batteries. By using an intercalation process of Li into a host structure, the reduction of a participating element (e.g. transition metal ion) can be achieved, and therefore the resulting change of the magnetization can be measured. The feasibility of this procedure has been proven by the successful reversible reduction of the ferromagnetic γ-Fe2O3 (maghemite) inside a SQUID, and the in-situ measurement of the magnetization.[1] In this study, we are transferring the concept shown for intercalation materials towards FeF3·3H2O as conversion material and show for the first time an operando tuning of magnetization during a conversion reaction. The reduction of FeF3·3H2O leads to a change in the magnetization over reversible cycling and is discussed to be a two-step process.[2,3] This could be confirmed by this study by comparing the changes in the magnetization with features appearing in the corresponding cyclic voltammogram. Additionally, the partial irreversibility of the FeF3·3H2O reduction/oxidation could be monitored. For the measurements, a customized electrochemical cell was used applying a two-electrode setup with Li as counter electrode. As electrolyte, a solution of LiTFSI in EMIM-TFSI was utilized in order to be compatible with the SQUID preconditions. Furthermore, the sample composition and structure were thoroughly examined at different charge states with ex-situ methods like ADF-STEM, EELS or Mössbauer spectroscopy which as well confirmed the formation of Fe(0) in the discharged active material. Magnetic characterizations at different charge states and temperatures will also be shown, i.e. ZFC/FC and hysteresis curves. [1] S. Dasgupta, B.Das, M. Knapp, R. A. Brand, H. Ehrenberg, R. Kruk, and H. Hahn, “Intercalation-driven reversible control of magnetism in bulk ferromagnets”, Adv. Mater., vol.26, 4639–4644, 2014. [2] L. Liu, H. Guo, M. Zhou, Q. Wei, Z. Yang, H. Shu, X. Yang, J. Tan, Z. Yan, and X. Wang, “A comparison among FeF3·3H2O, FeF3·0.33H2O and FeF3 cathode materials for lithium ion batteries: Structural, electrochemical, and mechanism studies”, J. Power Sources, vol.238, 501-515, 2013. [3] F. Badway, F. Cosandey, N. Pereira, and G. G. Amatucci, “Carbon Metal Fluoride Nanocomposites: High-Capacity Reversible Metal Fluoride Conversion Materials as Rechargeable Positive Electrodes for Li Batteries”, J. Electrochem. Soc., vol.150(10), A1318-A1327, 2003.

Resume : Increasing the energy density of credit card payments is essential in order to enable multiple functions and higher levels of security. Required energy density is about at least 1000 Wh/L. Currently, the maximum density energy reached for the Li-ion secondary cell is about 700 Wh/L at low discharge rates. These values are not high enough and difficult to reach in small objects. Moreover, primary Li metal cells can reach higher values but demonstrate high toxicity and poor safety. The choice of primary Li-air technology for energy storage is strongly motivated by the breakthrough brought by a theoretical energy density of about 10 times higher than the current Li-ion storage. This is due to the utilization of oxygen as positive material which is never ending supply in this battery because brought by air. With this consideration, the limitating material in these batteries becomes Li, which has a high energy density, so it becomes possible to achieve an energy density higher than 1000 Wh/L. Here, we will present a Li-air technology developed at CEA Tech which is a break with current Li-O2 systems: electrolyte is able to dissolve O2 in it and is not toxic and inflammable. As a result, the reaction at the cathode is only in liquid phase, the triple point is not required and the battery is not limited by air flux because O2 could be stored in solution.

Resume : Overlithiated rock salts are promising cathode materials for Li ion high energy applications. Despite the earlier results, they can offer much higher capacities (>250 mAh/g) than the stoichiometric compositions. This high capacity is associated to Li rich content that forms a good percolation network along the Li diffusion channels [1]. Lithium titanium sulfide (Li2TiS3), which has been reported by Sakuda et al. [2], demonstrated excellent capacity owing to the multielectron redox reactions. Upon cycling, more than two lithium ions were reversibly intercalated through the structure and the capacity reached 425 mAh/g. Besides these promising results, low electronic conductivity as well as poor cycling stability were also reported. To eliminate such disadvantages, doping can be an effective solution. Here, we propose new doped lithium titanium sulfide materials, which have been prepared by high energy ball milling. New material showed better cycling stability than the current material. For a comparison, we will also provide a comprehensive study of Li2TiS3 through fine characterization tools (XRD, SEM, EDX, ICP, GITT, ex situ and in situ XRD) in order to examine electrochemical and structural properties as well as the degradation mechanism. References: [1] J. Lee et al., Science, 343, 519-521 (2014) [2] A. Sakuda et al., Sci. Rep, 4, 4883 (2014)

Resume : Novel methyl imidazole-based fluorine containing electrolytes with wide electrochemical window and high ionic conductivity have great potential for rechargeable lithium-ion batteries. In this report, we synthesized and characterized a series of methyl imidazolium based fluorine containing electrolyte from the reaction with methyl imidazole, 1,2-dimethyl imidazole, 1,3 propane sultone, 1,4 butane sultone, and sulfonyl fluoride, respectively. The electrolyte with FSI- anion shows better performances such as high ionic conductivity, cyclic, and electrochemical stability compared to TFSI- anion based electrolytes due to the formation of stable solid electrolyte interface (SEI) layer on the electrode surface. Full Li-ion batteries based on these electrolytes (1 M electrolyte solution in ethylene carbonate/dimethyl sulfoxide solvent) using LiFePO4 cathode and graphite anode will exhibit good specific discharge capacity in conjunction with conventional methyl imidazole-based electrolytes. Moreover, FSI- anion based electrolyte shows excellent thermal stability. The structures of the resultant electrolytes were confirmed by 1H-NMR and 19F NMR spectroscopy. The properties and performances of the resultant electrolytes were investigated by differential scanning calorimetry (DSC), electrochemical impedance spectroscopy (EIS), cyclic and linear sweep voltammetry (CV and LSV).

Resume : We investigated that the recycling of protective layer for Ni rich layered oxide material for Li ion batteries. To decrease the electrochemical performance according to leaving of cathode powder in air was confirmed by various analysis due to formation of lithium residuals. The surface of protective layer was covered by the lithium residuals and that lead to cancel the coating effect. The residual lithium was decreased and the cell performance was recovered by applying the recycling process in this work. After the recycling process, the performance became similar to that immediately after the initial coating, and the coating layer showed a resurgence, which was confirmed by SEM and TEM images. The initial capacity for the initial coated Ni rich NCM and the sample after recycling was 209 mAh/g and 206 mAh/g at 1C, respectively. The cycle retention for the initial coated NCM and the sample after recycling was 93.4% and 92.6% after 50th cycles at 1C. It is concluded that the coating layer and the electrochemical performance was recovered by recycling process.

Resume : Lithium transition metal borates (LiMBO3, M= Mn, Co, Fe) has drawn considerable attention due to their promising properties such as high theoretical capacity (222 mAh/g), high energy density, lightweight, high stability against oxygen loss, abundance and environment-friendly material. In this work, Lithium manganese borate (LiMnBO3), Lithium cobalt borate (LiCoBO3) and Lithium manganese cobalt borate (LiMn0.5 Co0.5BO3) materials were synthesized by sol-gel technique. The crystal structure, morphology and electrochemical performances of the lithium transition metal borates were analyzed by X-ray diffraction (XRD), X-ray Photoelectron spectroscopy (XPS), Scanning electron microscopy (SEM), Transmission electron microscopy (HRTEM) and galvanostatic charge-discharge measurements. XRD result revealed the presence of monoclinic phase with C2/c space group. XPS analysis confirmed the valence state of the metal ions. Galvanostatic charge-discharge measurement result revealed that the sol-gel derived Lithium transition metal borates exhibited excellent electrochemical performance. The LiMnBO3, LiCoBO3 and LiMn0.5 Co0.5BO3 cathodes delivered the first discharge capacity of 106, 98 and 110 mAh g-1 at C/10 rate and stable cyclic performance was observed for all the three cathodes.

Resume : Development of high energy density lithium ion batteries is recently the scope of interest due to the growing demand for electric vehicles. A common approach is to implement high voltage cathodes, among which lithium-rich NMC (LRNMC) seems to be a promising candidate. One of the barriers to its utilization, however, is the performance fade. Even though extensive studies have been done on LRNMC structural changes upon delithiation/lithiation cycling, interactions occurring at the electrode/electrolyte interface are barely investigated. In this work, the passivation film (SEI) formation on LRNMC cathodes was studied at different states of charge by X-ray photoelectron spectroscopy (XPS). Furthermore, SEI characteristics at charged and discharged states have been compared. Finally, the effect of tris(pentafluorophenyl)borane (TPFPB) electrolyte additive and high temperature on the film composition was studied. At different delithiation (i.e. charge) states, a stable formation rate organic SEI compounds was observed while it altered for the inorganic ones. Moreover, different SEI thickness in the charged and discharged states confirms the repetitive attests decomposition/dissolution of some SEI components at high voltages. XPS results reveal that TPFPB additive participates in the SEI formation which contributes to a thicker passivation layer. Lastly, we confirm the SEI thickness growth on LRNMC cathode at elevated temperature following the exacerbated electrolyte degradation.

Resume : Power grids are deeply changing in recent years due to the rapid deployment of renewable energies and a growing worldwide energy demand. Energy storage systems are promising technologies to provide electric networks with ancillary services. Currently, few data referred to batteries operation in power network ancillary services utilization are available. This could limit the evaluation of battery technologies in relation to those applications. Li-Titanate technology is characterized by a high specific power and it guarantees high safety in stressful conditions. In this context, the performance of a Li-Titanate Toshiba® battery, subjected to a frequency regulation cycle, was studied by CNR-ITAE. In the meantime, the manufacturer (Toshiba) tested the battery module in CC (Constant Current) charge/discharge cycles. This paper reports the results coming from the testing campaign at CNR-ITAE throughout 250 test days. A comparison between battery degradation obtained during frequency regulation and constant current tests was analyzed. Battery performance indicators (such as SOH, capacity and efficiency reduction) were evaluated. Finally, in order to optimize the size of energy storage systems based on lithium titanate technology operating under primary frequency regulation conditions, an evaluation tool was implemented.

Resume : Driven by the rapidly growing demand for electric and hybrid vehicles, as well as portable consumer electronics there is an ever increasing need for high-performance lithium ion batteries (LIBs). Silicon is one of the most promising LIB anode materials because of its high theoretical specific capacity (>4200 mAh/g). Unfortunately, with this impressive capacity comes critically limiting characteristics that include low electrical conductivity and large volume changes during lithiation/delithiation (>300%) that can lead to material pulverization and rapid capacity fade. Hybrid materials offer potential solutions to these limitations because when combining the components new composite properties can emerge. Graphene aerogels are flexible high surface area porous materials that are electrically conductive. It is reasonable that a graphene aerogel host containing nanoscale Si guest could provide an advanced hybrid material that addresses the challenges facing Si LIB electrodes. In this presentation, the preparation, properties and prototype LIB applications of mesoporous graphene aerogels containing sub-10 nm diameter silicon nanocrystals will be discussed.

Resume : The demand for energy storage with higher energy density is increasing day by day and intensive researches are being carried out. Many kinds of research have been concentrated on the anode of lithium-ion battery with high energy density. However, the practically usable anode electrode material is very limited for a number of reasons. And commercial cathode still has low capacity, the effect of full-cell configuration using a high capacity anode is insignificant, which is an obstacle to the development of the entire energy storage device. The newly proposed conversion type cathode has a storage capacity of 10 times that of the existing intercalate cathode. Sulfur is an interesting cathode material due to its high theoretical capacity of 1,673 mAh / g, large quantities, very low cost and low toxicity. Theoretically, S-based cathodes are configured full cell battery with a Si or lithium metal anode can achieve four or five times the theoretical specific energy of a commercial C-LiCoO2 system. Despite the theoretical capacity of the sulfur, the practical steps mentioned above could not be reached because of insulating properties and large volume expansion of sulfur, and dissolution of the intermediate reaction product in the electrolyte results in the poor lifetime. In this study, we use a polymer with a channel to enclose sulfur particles to prevent volume expansion and dissolution, in addition, try to approach to impart mass transfer capability through hybridization with conductive graphene. The polymer with a channel is synthesized through a low-temperature heat treatment based on the difference of the vaporization temperature according to the degree of polymerization of the polymer. Through the channel, the lithium ion and the electron to be delivered to the sulfur contained in the polymer. All of the synthesis processes attempted in this study are scalable and very easy to mass-produce. The polymer used in this study is an aliphatic rubbery synthetic polymer and has a vaporization temperature of 60 ° C or less when it is in a monomer state. However, the vaporization temperature rises sharply according to the degree of polymerization, and when it is completely cured, it has a vaporization and decomposition temperature of 300 degrees or more. But in this work, the polymer in the hybrids mostly had a very low degree of polymerization in the MALDI-TOF analysis of the synthesized whole hybrids. This is because of the polymerization reaction, which originated from sulfur, terminated very quickly and the reaction was complete when the polymer met the sulfur and graphene particles. Due to the very low degree of polymerization of the polymer, the polymer can be vaporized at temperatures below 90 degrees, which results in many pores and channels on the surface and inside of the polymer from low-temperature heat treatment. Such a pore-forming polymer has superior mass transfer characteristics and high lifetime performance while offsetting the disadvantages of sulfur.

Resume : Metal chalcogenides (MCs), including metal sulfides, metal selenides and metal tellurides, have attracted tremendous attention for energy storage applications and development of rechargeable lithium-ion batteries due to their unique physicochemical properties (e.g. high electrical conductivity, good thermal stability, earth abundance, etc.). Especially, MCs possess higher theoretical specific capacities for rechargeable lithium-ion batteries compared to traditional intercalation electrode materials. In addition, metal chalcogenides tend to be more electrochemically reversible as compared to metal oxide counterparts due to their faster charge transfer kinetics. Recently, as an alternative anode material for replacing currently commercialized graphite or carbon-based anode materials, various layered inorganic materials are investigated because of their large theoretical capacity. Similarly large numbers of layered MCs are explored as intercalation anode materials for lithium-ion batteries. However, there is still a plenty of room for the development of new efficient anode materials from MCs families, especially 2D MCs (both layered and non-layered) operating in terms of both intercalative and non-intercalative mechanisms, since only a few studies are carried out for this type of materials. In this work, 2D MCs nanosheets (such as GaS, GaSe, GaTe and InSe) were prepared via liquid phase exfoliation approach and their application as anodes of Li-ion batteries was investigated in detail. Among these 2D MC nanosheets, InSe displays the most excellent rate capability and high specific capacity (926 mAh g-1 and 595 mAh g-1 at 50 mA g-1 and 2 A g-1, respectively). In addition, it shows exotic cycling stability. The capacity of it has increased with the increase of cycling numbers, which means the quality of a battery will be improved when the battery is used. This work opens up vast opportunities for InSe and other families of MC nanosheets to be scalably processed into flexible conductive composite films with a broad range of applications such as wearable electronics, optoelectronics, and other energy storage systems.

Resume : Mixed metal sulfides have recently attracted great attention for energy storage applications due to low cost and enhanced electrochemical performance compared to their oxide/hydroxides analogues [1,2]. Despite of being demonstrated as high performance energy storage electrodes, their charge storage mechanism is not yet fully understood. Herein, NiCoMn mixed sulfide nano-needles were evaluated as novel binder/additive-free electrodes for high-performance energy storage and the charge storage mechanism was tracked through various post-mortem measurements. A facile hydrothermal method was employed to synthesize NiCoMnS2 nano-needles which were then microstructurally probed by XRD, EDX, SEM and TEM analyses. Electrochemical properties of the prepared samples were examined through CV, GCPL and EIS measurements, revealing a high specific capacity of 138 mAh·g-1 (0.71 mAh·cm-2), excellent rate capability and exceptional cycling stability demonstrating a peculiar electro-activation over cycling. Post-mortem XRD and Raman spectroscopy of the sample at various state of the charge suggested formation of possible amorphous phases on the surface of sample. Based on the obtained results a charge storage mechanism was proposed for NiCoMnS2 in alkaline media. In addition, the prepared sample was integrated with rGO electrodes in an asymmetric device, exhibiting a maximum energy density of 36.2 Wh·kg-1 and power density of 16.5 kW·kg-1, with excellent long-term cycling and rate capability. Accordingly, we believe the present work not only sketches electrochemical behavior of NiCoMnS2 but also help better understanding the charge storage origin of mixed metal sulfides. References: [1] X.Y. Yu, X.W. Lou, Mixed Metal Sulfides for Electrochemical Energy Storage and Conversion, Adv. Energy Mater. 1701592 (2017) 1701592. [2] P. Kulkarni, N. Sanna Kotrappanavar, G.R. Balakrishna, D.H. Nagaraju, M.V.V. Reddy, Nanostructured binary and ternary metal sulfides: Synthesis methods and its application in energy conversion and storage devices, J. Mater. Chem. A. 5 (2017) 22040–22094.

Resume : Air batteries and fuel cells can be considered as promising energy conversion devices for portable applications such as the automotive sector. The oxygen reduction reaction (ORR) and, the dependence on the use of expensive noble metals remains as some of the main limiting factors for fuel cells and air batteries technologies. Transition metal oxides mixtures (TMOMs) have gained interest as novel catalytic materials due to its great stability; being their activity highly dependent on the nature and composition of the mixture. In the present work, we synthesized NiCo2O4 and Co3O4 spinels through a solvothermal methodology, and evaluated their electrocatalytic properties for the oxygen reduction reaction. X-ray diffraction patterns corroborated the crystal structure corresponding to NiCo2O4 and Co3O4; while, SEM micrographs revealed that, Co3O4 presented a nanosheet array forming a hierarchical semi-porous structure. In the case of NiCo2O4, it presented a flowerlike microstructure with sizes ranging from 3 to 5 μm. In terms of the electrocatalytic evaluation for ORR in alkaline medium (0.1 M KOH), both materials exhibited activity for ORR, being the hierarchical structure the Co3O4 material with the highest current density (3.5 mA cm-2). This value was achieved due to the greater active surface area of Co3O4. In terms of overpotential (η) compared with commercial Pt/C (20 wt.%), the Co3O4 and NiCo2O4 presented η values ranging between 160 and 180 mV.

Resume : A favorable electrolyte/separator for alkaline zinc-air batteries should possess high ionic conductivity, less zincate ion crossover, high electrochemical stability in caustic solution and high electrical resistance. Though commercial microporous films of polyolefins, namely, polyethylene and polypropylene, saturated with electrolyte are widely used as the separator. The microporous structure of the commercial films, which is ordered structure, usually leads to the lower performance of the batteries. Thus, non-ordered and layered-fibrous structures are suggested to improve the battery performances. Herein, separators based on electrospun polypropylene nanofibers were investigated. Electrospun syndiotactic polypropylene (s-PP) nanofibrous mat was fabricated using electrospinning technique. Granular s-PP was dissolved in a solvent mixture of decalin, acetone and DMF to the concentration of 7.5 wt%. The resulting solution was then electrospun under a controlled condition (Potential: 10.5 kV; Distance: 15 cm; flow rate: 0.8 ml/h). A three-electrode configuration cell with a zinc working electrode and a platinum counter electrode was used to examine electrochemical characteristics of electrospun s-PP nanofibers and Whatman filter paper. Also, the performances of the separators were examined using home-made tubular zinc-air batteries with stagnant electrolyte. Cyclic voltammetry elucidated the higher and broader peak for zinc dissolution was appeared on nanofibrous (s-pp) compared to the Whatman filter paper. The galvanostatic discharge results showed that the battery using s-PP nanofibers exhibited an improvement in the discharge capacity more than 40% compared to the Whatman filter paper.

Resume : High capacity sulfur electrodes are expected to serve to high energy density low cost next-generation lithium rechargeable batteries. Li/S cells involve a series of complex chemical reactions between solid and soluble sulfur species, causing severe morphological changes upon cycling and low practical performances. These changes at both electrodes upon cycling are still key parameters for Li/S batteries, while different strategies can be found in the literature to address these degradation mechanisms. In particular, operando X-ray diffraction techniques are interesting tools, providing qualitative and quantitative information on crystalline active species upon cycling. As well, X-ray absorption tomography allows changes in the global morphology of the electrodes to be studied upon cycling. In this work, X-ray tomography was combined with X-ray diffraction computed tomography, to follow operando the full cell behaviour thanks to morphological and chemical information, and then to investigate the ageing mechanisms of the cell components. Information on both electrodes could be recorded using a representative cell design, with electrolyte amount and pressure controls. As a perspective of this work, such a characterization tool could be applied by material scientists while designing and characterizing new solutions developed for Li/S cells.

Resume : There is a renewed interest in NiMH batteries with improved energy densities that could approach those of Li-ion batteries. Efforts to improve the energy density concentrates on alternative anode as well as cathode materials. For anode, AB2 and Mg based alloys are candidates with potentials that go beyond the capacity achieved with rare-earth based AB5 compounds. In a recent study [1] we have shown an AB2 alloy which is sluggish in its activation could readily be activated when it was surface modified with hot-alkaline treatment. The treatment resulting in fine porous surface rich in Ni not only activates the alloy but it also increases the discharge capacity by a significant amount. This was attributed to positive effect of porous surface where hydrogen evolution was made difficult by the associated stabilizing effect. For Mg based alloys, we have investigated A2B7 alloy where the amount of Mg is quite low and an amorphous Mg50Ni50 alloy. Here rather than modifying the powders, the electrode itself was modified by nafion coating. The electrodes were tested both in bare and coated form with a notable difference in discharge capacity. Nafion coating increased maximum attainable discharge capacity in both alloys up to 150%. Electrochemical impedance spectroscopy measurements showed that the charge transfer resistance increases with coating. The role of nafion coating in developing Mg based negative electrode materials is discussed. [1] Tan S., Shen Y., Sahin E. O., Noréus D., Ozturk T., "Activation behavior of an AB2 type metal hydride alloy for NiMH batteries" International Journal of Hydrogen Energy 41 (23), 9948-9953,2016

Resume : Sodium ion technology is one of the most powerful alternatives to other energy storage technologies currently marketed or in a development stage. Compared to classical system as the lead-acid battery, Na-ion technology surpass in energy, specific properties and environmental friendliness. In comparison with the other Li-based technologies (Li-ion, Li-S, Li-Air), Na-ion lowers the device prices for a similar value of autonomy. However, the size of Na+ and its lower redox potential (+0.3V higher than for lithium) are still defying a suitable Na-ion batteries (NIB) technology. Therefore, there is increasing interest in coupling adequate positive and negative electrodes for maximizing the final device energy [1]. Despite the chemical and electrochemical resemblances of Li and Na, a number of negative electrodes for LIB shows very limited or none activity against sodium. For instance, graphite can intercalate 1/70 mole of sodium instead of 1/6 mole of lithium. Due to this limitation there is a wide research on positive electrodes in order to obtain high voltage systems. Current research in sodium-ion positive electrodes is focused on few families of inorganic compounds, namely transition metal layered oxides with O3, P2 and P3 crystal structures [2]. In this work we investigate P2-type electrodes based on NaxLiyM1-yO2 (M=Mn, Ni, Fe, Cr…) electrodes. The presence of partial Li substitution in the transition metal layer may assist the structural stability upon cycling. The active materials were synthesized using a sol-gel or solid state method, and characterized by XRD, SEM, TEM and BET techniques. Cyclic voltammetry and galvanostatic tests were performed using a two-electrodes cell using the metal oxide as working electrode and metallic sodium as pseudo- reference and counter electrode. Electrochemical impedance spectroscopy studies were performed using a three-electrodes cell using the metal oxide as working electrode and metallic sodium as counter and reference electrodes. [1] B.L. Ellis, L. F. Nazar, Current Opinion in Solid State and Materials Science 16 (2012) 168 [2] M.D. Slater, D. Kim, E. Lee, C.S. Johnson, Adv. Funct. Mater. 23, 947–958, 2013.

Resume : Due to the limited Li resources, research on Na-ion batteries and capacitors is growing exponentially leading to the fast development of Na-based energy storage devices. When high energy density and power density are needed at the same time, hybridization between battery and supercapacitor electrodes can offer the figures of merit required. These devices are assembled by a battery-type and a capacitor-type electrode [1]. Regarding negative electrodes, titanates and hard carbon are the most studied in the recent years. Nevertheless, those materials provide limited energy density. Among the materials for higher energy density applications, Sn- and Sb-based alloys are some of the most promising alternatives [2]. In this communication we report the use of TiSb2 alloy as anode material for sodium ion batteries (NIBs) and capacitors (NICs). The electrochemical performance of TiSb2, synthesized by scalable methods, is investigated in NIBs. Stable cycling with a capacity of about 225 mAh g-1 is achieved for 200 cycles. The reaction mechanism is explored and discussed by means of operando XRD and ex situ TEM analysis. The excellent rate capability observed allows the use of TiSb2 in NICs combined with an activated carbon (AC) as positive electrode. The high energy densities achieved, of 132 Wh kg-1 at 114 W kg-1 and 65 Wh kg-1 at 11 kW kg-1 (Figure 1), are among the best reported values for alloying materials in NICs. However, due to the well-known problem of volume changes upon cycling of alloying materials, the capacity retention needs to be improved. By the use of a cross-linked functional binder as CMC-PAA we enhanced the retention after 1000 cycles from 10% to 63%, paving the way to develop new high-performance anodes for NICs. [1] G.G. Amatucci, F. Badway, A.D. Pasquier, T. Zheng, An Asymmetric Hybrid Nonaqueous Energy Storage Cell, J. Electrochem. Soc. 148 (2001) A930–A939. doi:10.1149/1.1383553. [2] M.Á. Muñoz-Márquez, D. Saurel, J.L. Gómez-Cámer, M. Casas-Cabanas, E. Castillo-Martínez, T. Rojo, Na-Ion Batteries for Large Scale Applications: A Review on Anode Materials and Solid Electrolyte Interphase Formation, Adv. Energy Mater. 7 (2017) 1700463. doi:10.1002/aenm.201700463.

Resume : Currently, one of the considered efficient hydrogen generation methods is high temperature water electrolysis. In recent years high temperature electrolyzers based on Solid Oxide Cells has been gaining interest because of their (i) high reaction rate, (ii) very good efficiency, (iii) no need to use noble metals as a catalysts, (iv) observed unique self-healing of the cells and (v) modular design makes it easy to scale-up the system based on SOEC stack. However, the drawbacks of operation at high temperatures are related to material stability problems which limit the durability of the SOEC. For this paper, SOEC mid-term operation was analysed experimentally. The test was performed on a single, planar 5cm x 5cm fuel electrode supported solid oxide cell, based on Ni-YSZ with effective area of the oxidant electrode of 16 cm2. The over 250 hour test was performed at constant current density (125 mA/cm2) and temperature (700°C). In parallel with experimental studies, numerical activities were performed. The existing and previously validated model of SOC electrochemical performance was enhanced with degradation parameters of the cell. Based on the realized experiments, the modified model was additionally verified. The prediction error did not exceed 5%. In this work, the degradation and performance drop of high temperature SOEC was investigated and discussed both experimentally and numerically. The observed degradation rate during the mid-term operation was 0.38 mV/h.