Sustainable materials for chemical and electrochemical energy storage

Resume : Due to high toxicity and controversial mining practices, energy storage materials such as high capacity battery cathodes containing cobalt are increasingly becoming unviable in the sustainable economy. This is particularly true of the layered manganese oxides such as LiNi(1/3)Mn(1/3)Co(1/3)O2 which, with their high capacity, would otherwise be ideal. While Co-free layered manganese oxides such as Li1.1Mn0.55Ni0.35O2 (LMNO) exist, these currently suffer from poor cycling stability and sluggish kinetics, reducing their longevity and, consequently, competitive edge. A route to improve the performance of these Co-free materials is thus of paramount importance. Key to the high performance of the layered manganese oxides is their ability to maximize the energy density of the cathode via nanoscale mixing of two structurally compatible components: a monoclinic C2/m Li2MnO3-like phase (M-phase) and a rhombohedral R-3m LiMn(1/2)Ni(1/2)O3-like phase (R-phase). Recently, we demonstrated that we can influence the morphology and distribution of these phases in Co-free LMNO on a particle-level scale through use of a spray-pyrolysis synthesis approach combined with targeted thermal calcination [1]. This approach segregates the Ni-rich R-phase to the outer surface of the LMNO nanoparticles, reducing structural degradation over the cyclic lifetime and ultimately delivering 160 mAhg-1 and 100 mAhg-1 at C/3 and 1C, respectively, with 80% capacity retention after 150 cycles. In this work, we further explore the potential performance improvements to LMNO that can be achieved by complementing the previous synthesis engineering approach with chemical doping with Al and Sn. We observe that low amounts of Al doping can increase the discharge capacity up to 187 mAhg-1 with a capacity retention in the same batch of 94.3% after 150 cycles. By studying a series of dopant concentrations from both species with a wide range of advanced characterization techniques, with a heavy emphasis on state-of-the-art advanced transmission electron microscopy methods, we are able to piece together a more comprehensive picture for the nanoscale structural and chemical origins of this performance increase, which we currently attribute to the dopant-dependent size distribution and composition of the two structural phases via the emergence of nanodomains. We conclude by exploring the prospects that this approach can be generalized to customize the nanoscale landscape and, subsequently, tune the electrochemical performance of all layered manganese oxide systems. [1] K. Rajappa Prakasha, J. Grins, A. Jaworski, T. Thersleff, G. Svensson, L.O. Jøsang, A.D. Dyrli, A. Paulus, D. De Sloovere, J. D’Haen, M.K. Van Bael, A. Hardy, H. Avireddy, J.R. Morante, J. Jacas Biendicho, Temperature-Driven Chemical Segregation in Co-Free Li-Rich-Layered Oxides and Its Influence on Electrochemical Performance, Chem. Mater. (2022). https://doi.org/10.1021/acs.chemmater.1c04150.

Resume : Traditional materials for rechargeable Li-ion battery electrodes are based on well-ordered crystalline materials containing scarce elements such as lithium and cobalt [1]. The strong focus on crystalline electrode materials have caused disordered/amorphous electrode materials to be overlooked in the past [2]. Thus, a number of well-performing, cheap and environmentally friendly materials may have been missed as candidates for rechargeable Li-ion battery electrodes. In this study, we have synthesized a monoclinic vanadium oxide, VO2(M), via thermal treatment of a non-distorted rutile VO2 phase and employed it as a cathode against a Li-metal anode. VO2(M) displays an irreversible broadening and loss of scattered intensity in the Bragg reflections when Li-ions are intercalated into the structure. This behavior is very similar to the disordering behavior of closely related rutile TiO2 electrodes, as reported by Christensen, et al. [3]. Similar to the TiO2 structure, VO2(M) has channels for Li migration along one crystallographic axis [4]. To investigate the irreversible order-disorder transformation in VO2(M), we collect operando powder x-ray diffraction and total scattering data during charge and discharge, i.e. Li-ion insertion and extraction, using an AMPIX battery test cell [5]. The data is analyzed using Rietveld refinement and pair distribution function analysis (PDF), respectively. The irreversible phase transformation begins after inserting 0.17 Li/V or approximately two hours into the first discharge at C/12. The broadening of the Bragg reflections increases with continuous intercalation of Li-ions. The subsequent complete charge and discharge look similar from the scattering, which indicate that after the irreversible disordering process, a reversible phase transition occurs in the disordered state. References [1] D. Larcher, et al., Nat Chem 2015, 7 (1), 19-29. [2] C. K. Christensen, et al., Journal of Physics: Energy, 3 (2021). [3] C. K. Christensen, et al., Nanoscale 2019, 11 (25), 12347-12357. [4] W. Li, et al., Journal of Alloys and Compounds, (2020), 812. [5] O. J. Borkiewicz, et. al., Journal of Applied Crystallography 2012, 45 (6), 1261-1269

Resume : Sodium and iron make up the perfect combination for the growing demand of sustainable energy storage systems given the natural abundance and sustainability of the two building block elements. Herein, the chemical space of a series of (meta)stable, off-stoichiometric Fe-PO4(-F) materials is unraveled. An interesting electrochemical activation phenomenon of Na0.6Fe1.2PO4 is described and the material displays excellent rate capability, and stability on long long-term cycling. Besides, the metastable crystalline Na1.2Fe1.2PO4F0.6 delivers a reversible capacity of more than 140 mAh g-1 with an average discharge potential of 2.9 V (vs. Na+/Na) resulting in a practical energy density of 400 Wh kg-1. Furthermore, this material also exhibits excellent capability in Li-ion batteries by electrochemical ion exchange proved by in-situ XRD. Overall, this study unlocks the possibilities of off-stoichiometric Fe-PO4(-F) cathode materials and also reveals the importance to explore the oft-overlooked metastable materials for energy storage.

Resume : The global rise of Li-ion battery (LIB) production is linked with a number of challenges, and in particular the growing risks of demand-supply mismatch and supply constraints of the raw materials. Within this scenario, Na-based batteries are rising as potential complementary technology to Li-ion batteries, as the combination of attractive properties potentially NIBs offer (i.e., low cost, sustainable precursors and secure raw material supplies), could represent an important step forward towards beyond Li technologies. Na-ion chemistry suffers however from some intrinsic drawbacks compared to Li-ion (heavier and larger alkali ion, 0.33V larger standard potential) which tend to lower cell voltage and capacity. Nevertheless, with ongoing development, materials available for Na-ion cells are approaching the energy density of the present generation of Li-ion commercial cells. In this talk, the potential of Na-ion batteries will be thoroughly analyzed and our recent research regarding positive and negative electrode materials will be reviewed. Results related to several phosphate-based families of cathode materials will be shown, together with the challenges of developing competitive anode materials. Finally, the use of high-throughput approaches applied to the screening and design of electrode materials for NIBs will also be discussed.

Resume : Current energy technologies rely on producing more than one billion lithium-ion batteries every year to power consumer electronics alone. The major challenge we face is the unsatisfactory energy density and slow charging performance of current lithium-ion batteries; they cannot meet the increasing demands from widespread and emerging applications, including electric vehicles, portable devices (i.e., smartphones), and many industry tools. One main goal is to develop new safe, efficient, and sustainable energy storage and conversion technologies to eliminate the severe fire risk and environmental issues caused by current technologies. This talk covers our research to address the above issues mentioned. We provide a new configuration strategy for the modification of conventional polyolefin separators by simply incorporation of appropriately engineered long and fine boron nitride nanotubes (BNNTs) without blocking the porous channels of the conventional separator for Li+ ion diffusion. This new BNNT separator exhibits improved thermal stability up to 150 °C, ensuring the safe operation of LIB cells at elevated temperatures [1]. Further Ion gel electrolytes show great potential in solid-state batteries attributed to their outstanding characteristics. However, because of the strong ionic nature of ionic liquids, ion gel electrolytes generally exhibit low lithium-ion transference number, limiting its practical application. Amine-functionalized boron nitride (BN) nanosheets (AFBNNSs) are used as an additive into ion gel electrolytes for improving their ion transport properties [2]. Moreover, migration of cycling intermediates (polysulfides) from the cathode to anode through a separator is one of the main problems in current lithium–sulfur batteries that deteriorates cycling performance of the cell. Here we report a multifunctional separator, which is constructed by incorporation of functionalized boron nitride nanosheets with negatively charged groups onto a commercial Celgard separator. The boron nitride separator is capable to prevent polysulfide migration through the separator effectively due to strong ion repelling of negatively charged polysulfides by the negatively charged boron nitride nanosheets. The lithium–sulfur cell with a boron nitride separator exhibits an excellent long-term cycling stability up to 1000 cycles and a high capacity of 718 mA h g–1 at a very high current of 7 C (1.18 A g–1) [3]. References: 1. M.M. Rahman, S. Mateti, Q. Cai, I. Sultana, Y. Fan, X. Wang, C. Hou, Y. Chen, “High temperature and high-rate lithium-ion batteries with boron nitride nanotubes coated polypropylene separators”, Energy Storage Materials, 19, 2019, 352-359. 2. D. Kim, X. Liu, B. Yu, S. Mateti, L. A. O’Dell, Q. Rong, Y. Chen, “Amine-functionalised boron nitride nanosheets: A new functional additive for robust, flexible ion gel electrolyte with high lithium-ion transfer number”, Advanced Functional Materials, 30, 2020, 1910813. 3. Y. Fan, M. M. Rahman, T. Tao, W. Li, S. Mateti, B. Yu, J. Wang, C. Yang, Y. Chen, “Repelling polysulfide ions by boron nitride nanosheet coated separators in lithum-sulfur batteries”, ACS Applied Energy Materials, 2, 2019, 2620-2628.

Resume : Wadsley-Roth phase titanoniobate is proposed to be one of the attractive anodes for fast-charging lithium-ion batteries due to its high theoretical capacity as well as the suitable channels for Li diffusion. Cation substitution is one of the most common used strategies for improving fast-charging ability of Wadsley-Roth phase titanoniobate anodes. In our work, the effect of iron substitution in Ti2Nb10O29 is uncovered from the novel aspect of decreasing the calcination temperature and thus shortening the length of Li diffusion channels with the smaller grains, which plays a significant role in optimization of the fast-charging ability. The pure Wadsley-Roth phase is obtained at 1000 ℃ with the certain degree of iron substitution (Fe: Ti: Nb = 0.4: 1.6: 10, denoted as FTNO1.6-1000) while a higher temperature is required for pristine TNO (e.g., 1100 ℃, denoted as TNO-1100). Benefiting from the reduced grain size along the diffusion channel, FTNO1.6-1000 presents enhanced rate ability with reversible capacity of 73.7 mAh g-1 at 50 C compared to the 1100 ℃ counterpart. Various electrochemical models confirm the improved diffusion coefficient and the reduced possibility of generating overpotential in FTNO1.6-1000. Furthermore, another novel effect of iron substitution is revealed by detailed operando XRD analysis, which indicates that the lattice variation during lithiation can be suppressed along a-direction. DFT calculations confirm and provide a theoretical explanation. Thus, FTNO1.6 electrodes exhibit enhanced durability after extended cycling at both 2 C and 10 C. Our work provides a simple strategy to improve not only the fast-charging ability but also the structural stability by iron substitution.

Resume : With electrification of society, the discovery of materials with higher energy densities, Li-ion storage capacities, and substantial stability at low voltages compared to graphite (theoretical capacity of 372 mA·h/g) is essential, but greener synthetic routes must also be the way forward. Herein, we report the hydrothermal synthesis of a novel rutile Fe2+/3+0.8Nb1.5O4.6 (FNO1) at 240 C for 48 hours in basic solution using stoichiometric ratios of Nb/Fe precursors. Rutile FNO1 crystalises in a disordered structure with corner- and edge-shared octahedral metals in the space group P42/mnm [1]. Nb/Fe atoms are randomly distributed over the octahedral sites in the tetragonal unit cell. When annealed in air, FNO1 collapses to a monoclinic FeNbO4 and Nb2O5 at temperatures above 750 C, due to Fe oxidation. This metastable FNO1 structure, when annealed under N2, transitions to an orthorhombic polymorph (FNO2) or an Fe columbite structure at 700 C. The orthorhombic polymorph has a layered structure of slightly distorted hcp oxygen sublattice with octahedral metal sites in the space group Pbcn [2]. 57Fe Mössbauer spectroscopy confirms that FNO1 has 90 % of Fe2+ and the remainder is Fe3+. More than 3 Fe sites are distinguished, revealing a complex disorder. FNO2 has similar proportions of the two oxidation states, with Fe2+ sites in a range of 92 to 97 %, and Fe3+ sites in between 8 to 3 %. X-ray absorption near edge structure (XANES) of a series of samples were analysed to determine phase stability under different annealing temperatures below (400 C) or above phase transition (900 C), and atmospheres (air or N2). For all samples, Nb K-edge XANES corresponds to Nb5+. The Fe K-edge showed that all samples annealed under N2 have oxidation state closer to 2+, but when annealed in air, Fe oxidises to 3+ above 400 C. EXAFS fitting agrees with Rietveld refinement, and only a disordered Fe/Nb crystal structure accounts for the local and bulk FNO1 crystal structures. On the other hand, an ordered columbite crystal structure provides a good agreement with the sintered FNO2 under N2. There is indication of Nb/Fe ordering within the stacking layers. Scalability to a few grams of sample was feasible using 200 mL stainless steel autoclaves, and the large batch samples were used to prepare an ink. A slurry composition was made of 80 % of active material, 10 % of C65 and 10 % of binder (PVDF in NMP), which was coated onto Cu foil. 15 mm discs were cut and assembled into coin cells. Cyclability (200 cycles) and capacity retention at various current densities were performed. The samples show different electrochemical performances because of their structures. FNO1 has the first discharge capacity (lithiation) above 600 mA·h/g and FNO2 above 300 mA·h/g. The theoretical capacity for both samples are 468 mA·h/g, corresponding to the insertion of 4.5 Li+ to reduce Nb5+ to Nb2+. However, these samples have different Li-ion mechanism upon insertion, which were characterised by ex-situ X-ray diffraction. FNO2 has better structural stability than FNO1, showing characteristics of an insertion type electrode. FNO1, in contrast, becomes less crystalline when discharge to 0.005 V. This amorphisation process could be related to a conversion type mechanism upon Li insertion. References: [1] Tealdi, C. et al. Columbite-type FexMn1-xNb2O6 Solid Solution: Structural and Magnetic Characterization. Physical Chemistry Chemical Physics 6, 4056-4061 (2004). [2] Hansen, S., et al. Cation Ordering Waves in Trirutiles - When X-ray Crystallography Fails. Acta Crystallographica Section A 51, 514-519 (1995).

Resume : The purchase of electric vehicles has increased from 13,000 in the year 2012 to 6.6 million in 2021. [1] This drastic increase is driven by changes in government policies, in an attempt to delay the worsening effects of climate change. Each of these electric vehicles uses a pack of lithium-ion batteries (LiB) weighing about 250 kg. [2] If the electric vehicle revolution is the next step toward carbon neutrality and sustainability, recycling of these batteries must be built in from the start. Current industrial and laboratory advances in recycling LiBs have significant biases towards the cathode. This bias results in the anode either being discarded or even pyrolysed, despite the fact that natural graphite appears on the EU's 2020 list of critical materials.[3] Here we demonstrate the use of water to delaminate disassembled anode sheets from a Nissan Leaf cell at its end of life, with the ability to recover high performing anode graphite. The technique utilises the hydrolysis of trace amounts of lithiated graphite to provide changes in pressure via the effervescence of H2 that dislodges the active material away from the current collector. This process provides a rapid, low-cost technique for graphite reclamation even in the case of PVDF bound material as utilised in these early cells. Analysis via XPS, Raman and SEM determined that graphite from highly deteriorated anode material had little degradation, however, the surface was coated with an organic residue. This indicates that battery ageing occurs via solid electrolyte interface growth or electrolyte degradation rather than cracking and exfoliation. The graphite extracted from batteries also had a similar crystallinity to that of pristine electrochemical grade graphite. Electrochemical testing of the extracted active material not only showed stable cycling close to the theoretical capacity limit for graphite but that they could outperform MAGE 3, an electrochemical grade graphite. [1] IEA (2022), Electric cars fend off supply challenges to more than double global sales, IEA, Paris https://www.iea.org/commentaries/electric-cars-fend-off-supply-challenges-to-more-than-double-global-sales. [2] Harper, G., Sommerville, R., Kendrick, E. et al. Recycling lithium-ion batteries from electric vehicles. Nature, 575, 75–86 (2019). https://doi.org/10.1038/s41586-019-1682-5. [3] Critical Raw Materials Resilience: Charting a Path towards greater Security and Sustainability, 2020. https://eur-lex. europa.eu/legal-content/EN/TXT/?uri=CELEX:52020DC0474.

Resume : It is imperative we mitigate and then reverse carbon emissions. COPS 26 just happened with the goal of global commitment to keep 1.5 C within reach by 2050. A green industrial revolution powered by many of sustainable innovations evolving in parallel is essential. Yet we need to make sure that this new revolution happens sustainably and does not create more damage. We must learn from past mistakes and learn how to see the bigger picture rather than immediate goals. Batteries and catalytic processes are key for delivering the green industrial revolution by storing the intermittent renewable energy and releasing it when is needed most to decarbonize our economy across various sectors. Yet, battery materials and catalysts for various sustainable technologies are facing real challenges as they are based on critical and expensive metals. In this talk, I will present recent research advances from my research team in the area of sustainable batteries with focus on Na and Al as well as the production of green H2 and sustainable plastics via electrocatalysis.

Resume : As Greta Thunberg claims – it is time to take severe action in order to stop the climate crisis. To do so we need to, as we all know, increase the use of renewable energy sources and use sustainable and green energy storage solutions. Unfortunately, the fantastic lithium-ion battery we use today is facing problems associated with element deficiency and large carbon emissions. Therefore, the challenge is to invent batteries composed of environmentally friendly compartments that have high capacity and high power as lithium-ion batteries. Our research group develops organic conducting redox polymers (CRP) as electrode materials for batteries. CRP material is associated with large resource abundance, low cost, and flexible properties. CRP constitutes of a polymer backbone, that contributes with very good electrical conductance, and a redox-active group, that is attached to the polymer and contributes with high capacity. The redox-active group we focus on is quinones that have the ability to cycle both metal ions and protons (H+). This versatile cycle ability is utilized to make both all organic quinone CRP proton batteries and hybrid quinone CRP metal batteries. To develop organic battery material, we have evaluated the versatile cycling chemistry of different quinones with several cycle ions. Moreover, we have also deposited our quinone CRP material on a porous carbon substrate in order to mass load material to enable higher capacity. This quinone CRP carbon construction has been used as an anode in a secondary manganese battery justifying that the concept works. Our current projects are about designing a battery consisting of quinone CRP material and calcium, magnesium, sodium, or potassium, and constructing an all organic battery using quinone CRP carbon electrodes and protons, which hopefully will provide new ideas within the green energy storage research field.

Resume : Currently, lithium-ions battery as the most important energy storage device has occupied most markets. High safety and high energy density batteries are still urgently required in our life. Some novel electrolyte matching high-voltage battery endurance has attracted much attention.[1] Concentrated electrolytes thanks to their large electrochemical window, are promising electrolytes.[2] We study here different concentrated solutions as electrolytes composed of LiTFSI salt and methanol solvent. Here a methanol-in-salt (MIS) electrolyte with 17 M LiTFSI in methanol is explored. As alcohol-based electrolyte with an alcohol solvation structure is formed, the 17 M electrolytes show better electrochemistry window which can reach a 3.13 volts potential platform and the maximum voltage can reach to 5.23 volts. The LiFePO4/active carbon and Li4Ti5O12/active carbon cells can cycle stably using the 17 M electrolytes. Furthermore, some high-voltage cell of LiMn2O4, Li1.03(Ni0.5Co0.2Mn0.3)0.97O2 still can work with the MIS electrolytes. A full cell using LiFePO4/Li4Ti5O12 can cycle more than 100 cycles with the 17 M electrolyte at a high-rate current. It shed a light that the nontoxic and low temperature alcohol-based electrolytes can be used in high-rate batteries in the future. Reference: [1] Wang Y, Zhong W-H. Development of Electrolytes towards Achieving Safe and High-Performance Energy-Storage Devices: A Review. ChemElectroChem. 2015;2:22-36. [2] Borodin O, Self J, Persson KA, Wang C, Xu K. Uncharted Waters: Super-Concentrated Electrolytes. Joule. 2020;4:69-100.

Resume : The expected growth over the next few years in the battery sector is huge, with approximately 7 million tons of new batteries manufactured per year. This growth is mainly triggered by the deployment of the electric vehicle and by the energy storage coupled to wind and photovoltaic generation. However, the massive development of the sector could become an environmental problem since most commercial batteries are based on inorganic materials such as lithium, nickel and cobalt in lithium-ion batteries or vanadium in flow batteries. These materials are scarce, their production in some cases is not sustainable and some are even toxic. In this context, the replacement of these materials by organic compounds based on elements as abundant as C-H-O-N has become a very promising alternative [1]. In this talk we will focus on exposing the enormous structural and synthetic possibilities of redox-type polymers and their application in different types of batteries including Li-ion and Post-lithium ion battery technologies. Among the huge variety of redox-active polymers, here I will present our recent research on Conjugated Microporous Polymers (CMPs) having redox functionalities as excellent candidates for battery electrodes. Conjugated microporous polymers (CMPs) are a unique subclass of amorphous polymers that combine extended π-conjugation with inherent 3D permanent microporosity, large specific surface area and high physicochemical stability. In this talk, I will present the synthesis

Resume : In recent years, lithium-ion batteries have established themselves as the primary power source for portable electronic devices and have seen widespread use in a variety of emerging applications, including electric cars and smart grids. Compared to conventional automobiles, electric vehicles have less direct emissions, which is favorable to maintaining global warming below 1.5 degrees Celsius, which would be critical for the future sustainable development of humanity. However, the current lithium-ion battery technology depends mostly on transition metal oxide cathode materials. These materials have a low theoretical energy density and are near to the theoretical value commercially. This raises a number of concerns in terms of the economics, environmental pollution, sustainability, and other related topics. Compared to inorganic electrodes, organic electrodes are comprised of resource-rich light components (such as C, H, O, N, P, S, etc.) and can be manufactured by mild procedures; some of these chemicals can even be extracted directly from natural plants, maximizing their environmental friendliness and sustainability. Furthermore, organic molecule architectures are varied and straightforward to build and regulate, allowing for better adjustment of theoretical capacity and operational potential, hence optimizing battery energy density. To summarize, organic electrodes may serve as a suitable alternative to inorganic electrodes in certain applications. Electroactive organic materials can be classified into three types: p-type, n-type and bipolar. For p-type organics, the reaction occurs between the electrically neutral state (P) and the positively charged state (P+), which outcome in oxidation followed by reduction in the battery; for n-type organics, the redox reaction occurs between the negatively charged state (N-) and the electrically neutral state (N); bipolar organics can lose electrons from the electrically neutral state to the oxidation state or gain electrons to the reduction state under different potential range. The organic molecule's redox active group determines the sort of electrochemical reaction. And the n-type molecules are the ones that get the most research because they can adapt to the characteristics of today's commercial batteries, as well as their better molecular flexibility for larger theoretical capacity. N-type organics, however, often have an operating voltage that is lower than 3 V versus Li+/Li0. As a consequence of this, the majority of the currently available Li-containing n-type organics are oxidized or hydrolyzed when they are handled in environmental circumstances (i.e., when exposed to oxygen and moisture). Therefore, when n-type organics are now used to organic batteries, lithium metal or its alloy is required as the negative electrode for lithium source since it does not contain lithium (in their oxidation states). This poses a significant threat to the industrial safety since the solution of lithium dendrites in liquid batteries is still indistinct. In addition to this, the battery with low working voltage limits the energy density of batteries. As a result, organic cathodes with n-type, Li-containing, and high working potentials (air stable) are critical for the further development of organic battery. The sulfonamides recently reported by our group fully achieve these goals, thanks to their high operating voltage and complete structural conjugation. In this manuscript, a further organic high-voltage, Li-containing and air-stable trifluorosulfonamide and cyanamide family has been revealed by molecular design based on sulfonamide, as indicated in scheme 1B. As knows, trifluoromethanesulfonyl group and cyano group are stronger electron-withdrawing groups compared to methansulfonyl group. The introduction of trifluoromethanesulfonyl group will increase the working voltage of the chemicals significantly, and different halogen substituents have also been investigated considering the electronic inductive effect further increases the working potential. Trifluorosulfonamide family include Li2-PDFSA (dilithium 1,4-phenylenebis((trifluoromethylsulfonyl)amide), Li2-DC-PDFSA (dilithium (2,5-dichloro-1,4-phenylene)bis((trifluoromethylsulfonyl)amide)), Li2-DF-PDFSA (dilithium (2,5-fluoro-1,4-phenylene)bis((trifluoromethylsulfonyl)amide)) and Li4-PTFSA (tetralithium benzene-1,2,4,5-tetrayltetrakis((trifluoromethylsulfonyl)amide)). Besides, the cyano group can improve the working voltage and at the same time because of its small molecular mass, it can also improve the theoretical capacity. The cyanamide family include Li2-PDCA (1,4-phenylene dicyanamide), Li2-DC-PDCA (1,4-dicyanamido-2,5-dichlorobenzene) and Li2-DF-PDCA (1,4-dicyanamido-2,5-difluorobenzene). The trifluorosulfonamide family has a very high redox potential, which ranges from 3.2V to 3.7V versus Li+/Li0. A redox potential of 3.7V versus Li+/Li0 for the Li2-DF-PDFSA is among the highest achieved so far for organic Li-containing cathodes, and this might serve as inspiration for the development of high working potential Li-containing organic cathodes and the creation of organic cathodes compatible with inorganic cathodes. Alternatively, the cyanamide family has a high redox potential between 3.1V to 3.3V versus Li+/Li0 as well as a high theoretical capacity. Take Li2-PDCA as an example; its specific energy at the level of the active material is up to 960 Wh Kg-1. Again, more importantly, all these cathodic materials are Li-containing (reduced phase), air-stable (oxygen and moisture).

Resume : Current societal challenges in terms of energy storage have prompted to an intensification in the research aiming at unravelling new high energy density battery technologies with the potential of having disruptive effects in the world transition towards a less carbon dependent energy economy through transport electrification and renewable energy integration. Aside from controversial debates on lithium supply, the development of new sustainable battery chemistries based on abundant elements is appealing, especially for large scale stationary applications. Interesting alternatives are to use sodium, magnesium or calcium instead of lithium and figures of merit attainable at the cell level computed using simple models indicate that the theoretical energy densities could easily top the state-of-the-art Li-ion, with costs being potentially much lower. While for the Na-ion case fast progresses are expected as a result of chemical similarities with lithium and the cumulated Li-ion battery know how over the years, for Ca and Mg the situation is radically different. On one hand, the possibility to use Ca or Mg metal anodes which would bring a breakthrough in terms of energy density, on the other, development of suitable electrolytes and cathodes with efficient multivalent ion diffusion are bottlenecks to overcome. The presentation will serve to discuss such promises and challenges, paying special attention to the research in materials which can potentially be used as positive electrodes. Overall, there is a long and winding road to follow before reliable proof-of-concept can be achieved and technological prospects evaluated. Development of reliable experimental setups, including reference and counter electrodes, coupled to complementary characterization techniques, as well as computational tools, is mandatory if steady progress is to be achieved.

Resume : Mg-air battery is a primary aqueous battery with high theoretical voltage and specific energy density. Aqueous Mg-air batteries consist of magnesium anode coupled with an air electrode. During the discharge, high self-corrosion rate and low utilization efficiency of Mg anode reduce the performance of Mg-air battery. Additionally, the layer of corrosion products precipitated on magnesium reduces the active surface of the anode. Several strategies evolved to overcome these issues, alloy development and electrolyte modification. Use of electrolyte additives is an effective way to control interfacial process. It is inexpensive and straight-forward approach for improving issues related to self-corrosion of Mg. As was previously shown, Mg2+ complexing agents are able to improve the anodic efficiency by decreasing the occurrence of self-corrosion and “chunk-effect” [1-3]. Usually the additives have higher impact on either utilization efficiency or discharge potential. The use of versatile electrolyte additive is needed. In this work we demonstrate the performance of 2,6-dihydroxybenzoate (2,6DHB) as versatile additive positively affecting both mentioned parameters. The presence of 2,6DHB in the electrolyte reveals simultaneous improvement of the discharge activity and inhibition of the self-corrosion of Mg-0.15Ca anode, leading to negative average potential and high anodic utilization efficiency. EIS measurements during the discharge and real-time hydrogen evolution measurements were used for elucidation of the effective mechanism. Additionally, 2,6DHB shows improvement of the discharge behavior for Mg-air battery with different alloys as anode material. [1] B. Vaghefinazari, D. Höche, S.V. Lamaka, D. Snihirova, M.L. Zheludkevich, Tailoring the Mg-air primary battery performance using strong complexing agents as electrolyte additives, J. Power Sources, 453 (2020) 227880. [2] L. Wang, D. Snihirova, M. Deng, B. Vaghefinazari, S.V. Lamaka, D. Höche, M.L. Zheludkevich, Tailoring electrolyte additives for controlled Mg-Ca anode activity in aqueous Mg-air batteries, J. Power Sources, 460 (2020) 228106. [3] D. Snihirova, L. Wang, S.V. Lamaka, C. Wang, M. Deng, B. Vaghefinazari, D. Höche, M.L. Zheludkevich, Synergistic Mixture of Electrolyte Additives: A Route to a High-Efficiency Mg–Air Battery, The Journal of Physical Chemistry Letters, (2020) 8790-8798.

Resume : Magnesium metal has been long-considered to be a safe and inexpensive alternative to lithium in rechargeable intercalation batteries due to its low cost, high abundance, and environmental safety. Due the diagonal relationship between lithium and magnesium they are also chemically similar, but with the extra valence electron of magnesium opening up the possibility of larger charger transfer during cycling of a cell to dramatically increase the overall energy storage of a device. Due to the breadth of materials available through choice of constituent elements, the transition metal dichalcogenide (TMDC) family has received a lot of attention over recent years for the wide range of properties they have demonstrated. In particular, their layered structure makes them ideal candidates for intercalation electrodes due to the weakly interacting layers separated by van der Waals gaps. Further to this, the layered material opens up the possibility to explore the effects of superlattice and heterostructure systems. Whilst many of these materials have been explored for use as lithium-ion batteries, there are few studies exploring them for use as magnesium-ion batteries. Using first principles density functional theory, we here investigate the whole family of TMDC materials and their heterostructures for use as Mg-ion intercalation electrodes. We are able to predict their open-circuit voltages, the electrical conductivity and volumetric expansion, properties which are all vital for the choice of an effective electrode material. We are also able to use thermodynamic to comment on the stability of these materials during cycling of a cell and predict the Mg capacity, a quantity that is vital for maximising the overall energy density of a battery.

Resume : The cost-effectiveness, safe operation and high energy density of rechargeable zinc-air batteries (ZABs) make them promising candidates for energy storage devices. A ZAB typically contains two electrodes, the air electrode and the metallic zinc electrode, separated by an alkaline electrolyte. The air electrode is usually carbon based. Oxygen reduction and oxygen evolution reactions (OER and OER) occur at the air electrode, both of which suffer from poor kinetics. This affects the efficiency and cycle life of a ZAB. Using effective electrocatalysts can improve the performance of ZABs. Precious metals, like Pt and Ru, have typically been used as ORR and OER electrocatalysts, respectively. However, these metals are rare and expensive and are not stable during cycling. Alternative electrocatalysts include transition metal oxides (TMOs). Although TMOs are inexpensive, effective and abundant and have high activities towards both ORR and OER, they suffer from poor electrical conductivity. Coupling TMOs with conductive carbonaceous materials can lead to high performance, nano-engineered air electrodes with sufficient electrical conductivity. In this work, spinel type MnCo2O4 was coated on carbon fibers (MnCo2O4/CF), which were utilized to make air electrodes. Asphaltene, the by-product of oil sands operations was used as a novel precursor for carbon fiber. A polyacrylic acid (PAA)-KOH hydrogel was used as the electrolyte to prepare all solid state ZABs. Scanning/transmission electron microscopy (SEM/TEM) and x-ray photoelectron spectroscopy (XPS) techniques were employed to characterize the electrode material. Rheological and visual tests were carried out to investigate the properties of the hydrogel electrolytes. The battery performance was examined in terms of full cell charge/discharge voltage, power density and cycling life in the temperature range of 25oC to -45oC and was compared with ZABs using air electrodes with the benchmark Pt-RuO2 electrocatalyst. MnCo2O4/CF had superior performance to that of Pt-RuO2 at all temperatures. The efficiencies at 10 mA/cm2 for MnCo2O4/CF and Pt-RuO2 were 63.1% and 61.3%, respectively, at 25oC and 53.0% and 42.8%, respectively, at -10oC. MnCo2O4/CF was able to complete 200 charge/discharge cycles even at -45oC without failing, while Pt-RuO2 was unable to complete 200 cycles even at 25oC.

Resume : Aqueous zinc-ion batteries are compelling next-generation energy storage devices due to the merits of zinc metal including mineral abundance, stable electrochemical activity, low cost, and environmental friendliness. However, one of the issues leading to zinc-ion battery capacity decay is zinc dendrite growth which will puncture the separator. Although there are a lot of efforts have been devoted to preventing dendrite like anode surface modification and electrolyte manipulation, understanding of science foundation of zinc deposition in electrolyte remains limited. In this work, we comprehensively study the dependence of zinc morphology on different deposition conditions (current density and capacity) with combined characterization method of liquid cell transmission electron microscopy and SEM. We found that in the most widely used zinc electrolyte ZnSO4, the nuclei density of deposited zinc will increase with the increasing current density from 1 mA cm-2 to 120 mA cm-2. Contradicted with the general kinetics understanding of metal nucleation model Sand’s time which said high current density will render short zinc dendrite formation time, we found that a high current density like 120 mA cm-2 can generate more nuclei active sites and more uniform surface. We attribute it to the thermodynamics factor, which means high current density can enable high energy nucleation seeds while low current density can only active low energy nucleation sites like grain boundary. The crystallographic orientation of zinc texture behavior was also studied by XRD with the indicator of the peak intensity ratio of (002)Zn and (101)Zn. The deposited zinc at ultrahigh current density 120 mA cm-2 shows the highest I002:I101, which means the surface is (002) plane dominated. Since (002)Zn is parallel to the electrode, more (002) plane indicates the electrode is more uniform and flatter, which is consistent with the previous result. Finally, based on this finding, we developed a simple method to prolong the cycling performance of zinc-ion battery without any modification. This work not only unravels the nucleation behavior of zinc from low current density to high current density, but also provides an effective strategy to achieve long-term zinc-ion battery.

Resume : Metal-organic framework (MOF) glasses have recently attracted increasing attention as promising anode materials for lithium-ion batteries (LIBs) due to their multiple advantages of open network structures, large surface area, and abundant reaction sites. However, the reversible capacities of MOF glasses still need to be improved to match the rapid development of green energy technologies [1, 2]. Silicon is a promising candidate for the next generation of LIB anode but suffers from vast volume changes upon lithiation/delithiation. To mitigate this problem, we combine nano-Si with MOF glass to create composite-based anode and thereby to obtain the synergistic effect of both materials, i.e., the integration of the high capacity of Si with the confinement effect of MOF glass. Specifically, we present a strategy to in situ grow a kind of MOF, namely, cobalt-ZIF-62 (Co(imidazole)1.75(benzimidazole)0.25) on the surface of Si nano particles, and then to transform the thus-derived material into Si@ZIF-glass composite (SiZGC) through melt-quenching. The robust hierarchical structure of the SiZGC based anode exhibits the specific capacity of ~650 mA h g-1, which is about three times that of pure ZIF glass and about six times that of pristine ZIF crystal at 1 A g-1 after 500 cycles. The origin of this huge enhancement is revealed by performing structural analyses. The unique structure of ZIF glass can not only enhance lithium storage, but also buffer the volume changes and prevent the aggregation of Si nano particles during lithiation/delithiation processes.

Resume : Si-based anode materials are considered as potential materials for high-energy lithium-ion batteries (LIBs) with the advantages of high specific capacities and low operating voltages. However, significant initial capacity loss and large volume variations during cycles are the primary restrictions for the practical application of Si-based anodes. Herein, we propose an affordable and scalable synthesis of double-layered SiOx/Mg2/SiO4/SiOx composites through the magnesiothermic reduction of micro-sized SiO with Mg metal powder at 750 °C for 2 h. The distinctive morphology and microstructure of the double-layered SiOx/Mg2/SiO4/SiOx composite are beneficial as they remarkably improve the reversibility in the first cycle and completely suppress the volume variations during cycling. In our material design, the outermost layer with a highly porous SiOx structure provides abundant active sites by securing a pathway for efficient access to electrons and electrolytes. The inner layer of Mg2SiO4 can constrain the large volume expansion to increase the initial coulombic efficiency (ICE). Owing to these promising structural features, the composite prepared at a 2:1 molar ratio of SiO to Mg exhibited initial charge and discharge capacities of 1826 and 1381 mAh g-1, respectively, with an ICE of 75.6%. Moreover, it showed a stable cycle performance, maintaining high capacity retention of up to > 86.0% even after 300 cycles. The proposed approach provides practical insight into the mass production of advanced anode materials for high-energy LIBs.

Resume : Sustainable energy production being inherently intermittent, storage of electrical power represents the bottleneck towards a net-zero economy. One attractive storage option is the electrolysis of water utilizing electrolyzers, which are electrochemical cells splitting water into oxygen at the anode and hydrogen at the cathode. Of these two half-reactions, the oxygen evolution reaction (OER) is the more challenging one, so that reducing the overpotential required for this half-reaction is most urgently needed to improve the overall device efficiency. We establish the applicability of additive manufacturing towards the generation of titanium alloy scaffolds for water oxidation electrodes. The scaffolds can be subsequently nanostructured by electrochemical anodization to enhance their surface area and coated with iridium as the electrocatalyst. We focus on the characterization of the functional electrodes in process-relevant conditions (1 M H2SO4, 60 °C, stirring) in terms of their performance and stability. The results establish the viability of a manufacturing procedure in which 3D printing of electrode scaffolds is used as a versatile method of generating non-planar and highly controlled geometries, combined with anodization to generate an electrocatalytically active surface of high area and subsequent atomic layer deposition (ALD) of the noble metal. Specifically, the Ti6Al4V powder suitable for selective electron beam melting (SEBM) can be rendered stable in hot, concentrated acid electrolyte using our methods. Importantly, low overpotentials can be achieved using minute amounts of iridium catalyst coating (< 10 nm) in comparison with the μm thick coatings traditionally used in electrolysis cells. Furthermore, the preparative methods used offer a variety of experimental parameters in order to optimally adjust the electrodes to each application. We have characterized eight distinct quantitative values to characterize electrocatalytic performance and stability from various viewpoints. Four parameters characterize performance and include the electrochemically active surface area, the mass activity with respect to EDX Ir quantification, the maximal current density, and the overpotential initially required to reach 10 mA/cm². Another four parameters represent stability in terms of overpotential after 100 h, the change in maximal current density after 100 h, the losses of Ir in the electrolyte and the change in EDX-determined Ir loading. We offer a holistic approach to choosing electrode types based on specific boundary conditions for applications in realistic operation conditions. The highest current densities are achieved with the electrodes anodized in ethylene glycol, whereas the best performing electrode type overall (considering noble metal utilization as well) is the one anodized for 2 h in glycerol without annealing. The latter type is in fact also the most balanced one if both performance and stability are considered. The most stable type is the one anodized in glycerol for 2 h and annealed. [1] [1] A. Hofer, et al., Electrochim. Acta 2022, 417.

Resume : In this work, we introduced novel, and simple electrochemical principles to guide the choice of the safe and valid operating potential window profile for carbon-based hybrid supercapacitor. The start vertex potential of the cyclic voltammograms (CVs) is set as the potential of zero charge (PZC). However, the final potential limit is chosen after elucidation of the storage mechanism using the CVs measured at various potential scan rates across the overall examined potential window. In addition, the mass and charge balance of the fabricated hybrid electrodes are rationally designed after evaluation of the potential window of the two separate electrodes. Using those strategies, a record performance merits are achieved of a hybrid device made up of carbon derived from biomass and carbon derived EDTA salt. The assembled device exhibits a specific capacitance 265 F/g at 5 mV/s and 221 F/g at 1 A/g with a high capability rate. Moreover, the device shows exceptional stability over 10,000 cycles with 100% capacitive retention and near 100% columbic efficiency. Most importantly, attaining a battery-like energy level of 99.2 W h/kg is a proof of concept that validates the proposed electrochemical fundamental methods for monitoring the mass ratio balancing of the hybrid cell electrodes.

Resume : Owing to the increasing demand for sustainable and eco-friendly energy storage devices such as supercapacitors, it is vital to continuously search for highly stable and cost-effective electrode materials with high energy and power densities. Herein, a 3D/2D metal-free mesoporous composite of graphitic carbon nitride (GCN) and bioderived carbon (Bio-Cx) is investigated as an energy storage electrode material. This composite overcomes the low conductivity and low capacitance limitations of GCN while enjoying its high corrosion resistance, high nitrogen content, and unique 2D structure. The GCN/Bio-Cx composite exhibits a fairly wide operating potential window of 1.2 V in 0.5 M H2SO4 aqueous electrolyte with a high capacitance of 300 F/g at 1 A/g. This high performance was ascribed to the huge number of available active sites, large surface area, and the unique 3D/2D structure. The assembled device employing the GCN/Bio-Cx composite as the positive electrode and mesoporous nitrogen-doped carbon (MPNDC) as the negative electrode showed an ultrahigh-energy density of 53.72 Wh/kg and a power density of 900 W/kg. The GCN/Bio-Cx//MPNDC device retains ∼100% of its initial capacitance after 13 000 charge/discharge cycles with 100% Columbic efficiency

Resume : We report a facile low-cost thermal polymerization method of urea to produce 2D carbon nitride nanosheets (GCN) as confirmed via a plethora of morphological and structural characterization techniques. The GCN electrodes showed excellent electrochemical performance with a very wide operating voltage window upon their use as positive and negative poles in supercapacitor devices. The GCN exhibited high specific capacitance as positive and negative electrodes in 0.5 M H2SO4. The symmetric supercapacitor (GCN//GCN) device possesses a wide operating voltage window of 2 V, with an ultrahigh energy density of 19.33 Wh/kg and superior stability over 21,000 charge/discharge cycles. The device was assembled on graphite sheet and not on Ni foam to avoid the raised caveats on the contribution of the redox-active Ni foam to the measured capacities. These unique properties can be ascribed to the high nitrogen doping level (exceeding 12%), revealing the potential of pristine GCN as promising candidates for further investigation and development in energy conversion and storage applications

Resume : We report on the optimized fabrication and electrochemical properties of ternary metal oxide (Ti-Mo-Ni-O) nanoparticles as electrochemical supercapacitor electrode materials. The structural, morphological, and elemental composition of the fabricated Ti-Mo-Ni-O via rapid breakdown anodization are elucidated by field emission scanning electron microscopy, Raman, and photoelectron spectroscopy analyses. The Ti-Mo-Ni-O nanoparticles reveal pseudocapacitive behavior with a specific capacitance of 255.4 F g-1. Moreover, the supercapacitor device Ti-Mo-Ni-O NPs//mesoporous doped-carbon (TMN NPs//MPDC) device exhibited superior specific energy of 68.47 W h kg–1 with a corresponding power density of 2058 W kg–1. The supercapacitor device enjoys 100% Columbic efficiency with 96.8% capacitance retention over 11,000 prolonged charge/discharge cycles at 10 A g–1

Resume : In the era of miniaturization, micro energy storage devices become an essential part of the progress in many fields starting from simple sensors to medical devices. However upcoming developments in all these fields are restricted to finding safe, reliable and high-performance micro batteries with the shapes that is not limited only to rectangles, cylinders, and pouches. The research is confronted with challenges of fitting a battery into a microdevice. Lithium-ion batteries (LIBs), a mature energy storage technology, are a leading candidate for the development of micro batteries that can be easily integrated into microelectronic devices. However, despite significant achievements in the field of micro batteries, limitations in areal capacity and in power densities still motivate the search for alternative designs and novel concepts in the battery field. Insufficient areal energy density from planar micro batteries has inspired a search for three-dimensional micro batteries. The power output of a three-dimensional micro battery is expected to be higher than that of a two-dimensional battery of equal size, as a result of the higher ratio of electrode-surface-area to volume and lower Ohmic losses. Within a battery electrode, the 3D architecture provides large surface area, increasing power by reducing the diffusion path for Li ions. Additive manufacturing, also known as 3D printing, has appeared as a novel class of free form fabrication technologies that have a variety of possibilities for the rapid creation of complex architectures at lower cost than conventional methods. 3D printing enables the controlled creation of functional materials with three-dimensional architectures, representing a promising approach for the fabrication of next-generation electrochemical energy-storage devices and has many unique advantages over conventional manufacturing methods. In this work, printer is employed to print a 3D micro battery with MXene electrodes that can be printed easily and can be fitted into any small device.

Resume : The scope of much energy related research today is to move towards more renewable energy sources. Existing components and materials within these sources should therefore be replaced with more green alternatives, e.g., iron, titanium, and sodium. The latter has, within battery research, also received a lot of attention in recent years due to the similarities to the well-established Li-ion battery technology, i.e. much know-how can be transferred to Na-ion batteries. Furthermore, sodium has a great abundance which is the main reason for the categorization of sodium to be a promising alternative to the Li-ion battery [1, 2]. However, when changing from lithium to sodium, challenges arise. One of these challenges is structural disordering being induced in some electrode materials during charge and/or discharge [3]. This is, among others, observed in layered sodium chromium oxide, NaCrO2. When Na-ions are extracted from NaCrO2 during battery charge the material is subjected to different structural transitions. When the Na-extraction exceeds a certain limit, the material suffers from severe capacity decay due to the formation of a highly disordered phase [4-6]. In this study, the structural evolution of NaCrO2 during Na-ion extraction and insertion has been investigated by operando X-ray diffraction which reveals a previously overlooked and unexplored crystalline intermediate during charge [7]. Furthermore, the disordered phase has been investigated through total scattering and pair distribution function analysis. The material in general has been studied through transmission electron microscopy and energy dispersive X-ray analysis to evaluate the particle size distribution and, moreover, the distribution of Na in the material both before and after Na extraction (charge). 1. Hwang, J.-Y., S.-T. Myung, and Y.-K. Sun, Sodium-ion batteries: present and future. Chemical Society Reviews, 2017. 46(12): p. 3529-3614. 2. Yabuuchi, N., et al., Research Development on Sodium-Ion Batteries. Chemical Reviews, 2014. 114(23): p. 11636-11682. 3. Christensen, C.K. and D.B. Ravnsbæk, Understanding disorder in oxide-based electrode materials for rechargeable batteries. Journal of Physics: Energy, 2021. 3(3): p. 031002. 4. Bo, S.-H., et al., Layered-to-Rock-Salt Transformation in Desodiated NaxCrO2 (x 0.4). Chemistry of Materials, 2016. 28(5): p. 1419-1429. 5. Yu, C.-Y., et al., NaCrO2 cathode for high-rate sodium-ion batteries. Energy & Environmental Science, 2015. 8(7): p. 2019-2026. 6. Kubota, K., et al., New Insight into Structural Evolution in Layered NaCrO2 during Electrochemical Sodium Extraction. The Journal of Physical Chemistry C, 2015. 119(1): p. 166-175. 7. Jakobsen, C.L., et al., Expanded solid-solution behavior and charge-discharge asymmetry in NaxCrO2 Na-ion battery electrodes. Journal of Power Sources, 2022. 535: p. 231317.

Resume : In this study, experimental determination and computational prediction have been combined to examine the formation of a mixed amide-hydride solid solution for the CsNH2-CsH system with a wide compositional range. The experimental results strongly suggest that a full amide-hydride solid solution Cs(NH2)xH1-x with a stable cubic structure is obtained for amide molar fractions ranging from 0.1 to 0.9.These results regarding the formation of a solid solution are theoretically evaluated by first-principle calculations, including the simulations of IR/NMR spectra and the calculations of the dipolar coupling constant. The agreement of experimental and computational data allows for a full assessment of a material's functional properties and structural identification.

Resume : Li-O2 batteries are highly promising energy storage devices. With organic electrolyte, the theoretical specific energy can be as high as ca. 3500 Wh kg-1, which far exceeds that of the state-of-the-art lithium-ion batteries of ca. 380 Wh kg-1. A Li-O2 battery is usually consisted of a Li metal anode, an organic electrolyte and a porous carbon-based cathode. A practically viable system with high energy efficiency and long-term stability is still highly demanded, although tremendous efforts have been devoted. The sluggish cathode reaction kinetics result in high discharge-charge overpotential and low energy efficiency. Perovskite oxide have been widely investigated as bi-functional catalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). However, most reported perovskites are composited with carbon-based materials as the cathode for Li-O2 batteries. The carbonaceous component reacts with the discharge product and generated Li2CO3, which lowers the stability. The highly active oxygen species, such as LiO2− and singlet oxygen, attack the carbon substrate and organic electrolyte during discharge-charge process. The side reaction leads to cathode degradation as well as electrolyte decomposition. Herein, we reported a carbon and binder free perovskite oxide cathode for Li-O2 batteries with molten salt as electrolyte, operating at elevated temperature. It exhibits a small overpotential of 50 mV during discharge and charge process. Furthermore, the battery can cycle for over 100 cycles without obvious degradation. Our work hints a tremendous potential of the perovskite cathode materials in Li-O2 batteries and may open up a completely new research field.

Resume : Organometallic trihalide perovskites exhibit high power conversion efficiency, making them potential candidates for next-generation photovoltaic solar cells. In addition to their unique physical and optoelectronic properties, perovskites have strong optical absorption in the visible range, ambipolar charge transport, high carrier mobility and long photo generated carrier diffusion lengths. The ionic response of these materials is quite high. As a result, these materials are also equally promising for energy storage applications. Recently, halide perovskites have been used in supercapacitors due to their large surface area and good ionic mobility with different charge storage characteristics. One of the critical aspects of halide perovskites for electrochemical energy storage application is the ion migration in the active electrode. A significant increase in capacitance is achieved by combining halide perovskite and carbon nanoparticles. Although a complete knowledge of the charge-storage mechanism in halide perovskite-based supercapacitors is still lacking, the ionic conductivity of the active electrode in perovskite enhances the overall charge storage capacity. The ionic conductivity of MAPbI3 samples is substantially higher than that of MAPbBr3 samples because the Pb-Br link is shorter than the Pb-I bond. As a result, bromide-perovskite-based supercapacitors have an overall energy density of 10 – 12 Wh kg-1. Iodide-based perovskites, on the other hand, are extremely unstable in the environment. As a result, the best feasible solution for reliable and efficient energy storage applications may be to manufacture mixed halide perovskite-based supercapacitors. There has been a general approach for preparing mixed halide perovskites by mixing methylammonium iodide (MAI) and methylammonium bromide (MABr) in the precursor solution. However, due to the phase segregation, inhomogeneous iodine-rich and bromine-rich perovskite thin films are formed. Due to local inhomogeneity and enhanced ionic conductivity, these materials are unstable. Another method is to make single crystals of MAPbBr3 and MAPbI3 and mix them in powder form to retain the nanoparticles in their purest phases. We have prepared a series of porous electrodes for supercapacitor applications by combining powders of various halide-based perovskite single crystals. We've shown that a specific bromide composition to iodide ratio with an energy density of 22 Wh kg-1 and a power density of 600 W kg-1 achieves maximum efficiency. The ionic conductivity of the mixed halide sample is at least two orders higher than that of pure halide perovskites, at 3.2 ×10-13 m2 s-1, while charge transfer resistance is reduced to 40.5 cm-2. With increased iodide content, however, overall device stability and coulombic efficiency diminish. With bromide ions in excess, cyclic stability of roughly 87 percent and columbic efficiency of 89 percent can be achieved.

Resume : With an increasingly more mobile society, the use of Li-ion batteries has never been greater. In order to satisfy our needs for better energy storage solutions, researchers have been looking into replacing traditional liquid electrolytes with novel ceramic electrolyte materials. The use of such electrolytes can greatly improve the energy density and life cycle of Li-ion batteries, while simultaneously making them safer and more environmentally friendly. Li7La3Zr2O12 (LLZO) has shown to be one of the most promising material in this regard due to its exceptional properties. However, the development of solid electrolytes still faces numerous challenges before they can be implemented in a more widespread use, such as a lower ionic conductivity compared to liquid electrolytes as well as the difficulty at which these materials are fabricated and implemented. In our study, we look at how different synthesis methods, and the addition of doping elements affect these issues. In this we have conducted a comparative analysis on the thermal, structural, and electrochemical properties of undoped and Al-doped LLZO prepared through solid state and sol-gel methods. An in-situ thermal analysis on the synthesis of LLZO was conducted by means of high temperature X-ray diffraction (HT-XRD) as well as thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). This allowed us to analyse the synthesis pathways, optimal synthesis conditions and thermal stability for each type of LLZO in our study. The analysis showed which secondary and intermediary phases are formed during synthesis, the rate at which they can they be integrated into the LLZO structure and the point at which LLZO starts to decompose, allowing us to optimize the synthesis temperatures and times. The most surprising result was that Al-doping improved the thermal stability LLZO by up to 50 C and lowering its decomposition rate for both synthesis methods, thus allowing for a wider temperature window in which LLZO could be synthesized. Electrochemical measurements by means of electrochemical impendence spectroscopy (EIS) reveal how the use of sol-gel synthesis increases the ionic conductivity by 3 to 6 times compared to its solid state counterpart and further improves the activation energy for Li-ion movement, due to the more tightly bound LLZO grains, which were observed with a scanning electron microscope (SEM). As a result, the highest conductivity was achieved for Al-doped sol-gel LLZO with an ionic conductivity 4.96 × 10-4 S/cm and an activation energy of 0.28 eV. This work provides a better understanding of how different synthesis methods, and the use of dopants affect the properties of LLZO solid electrolytes. Studies like this can bring new insight to the effect of various parameters on the properties of solid electrolyte materials, as we strive to improve the properties of solid electrolytes and making them more competitive to their liquid counterparts.

Resume : The ion exchange membranes (IEMs) have properties that can selectively separate cations and anions and have been used for electrochemical salinity gradient power generation and desalination, such as electrodialysis, capacitive deionization, reverse electrodialysis, and capacitive mixing. In this study, silica embedded pore-filling IEMs with low resistance were prepared by simple impregnation process to improve the performance of reverse electrodialysis. For this work, composite porous substrates, composed of porous substrate and silica, were fabricated by using simple wetting process of a dispersion solution including nano-sized silica. After that, the composite substrates were impregnated with mixture of electrolyte, crosslinking agent, and photo-initiator for filling of pores in substrate by electrolyte polymer. The impregnated substrates were irradiated by ultraviolet ray for radical polymerization of electrolyte and crosslinking agent. The prepared silica-containing pore-filled composite IEMs has a low resistance of 1.0 Ω∙cm2 or less, a high ion exchange capacity of 1.0 meq/g or more, and a high permselectivity of 90% or more. We expect that the IEMs will attribute to improve the performance of reverse electrodialysis.

Resume : Lithium-ion batteries (LIBs) have been considered as the main energy sources in a large variety of fields such as portable electric device and electric vehicles. However, the high cost and safety troubles make traditional LIBs unable to meet the requirements for safe and economical power applications. In various alternative, Magnesium (Mg) is high energy density and good safety and low cost. However, according to a previously reported studies, Mg ion batteries (MIBs) systems use Mg metal as anode materials which typically reacted with electrolyte species and results in the formation of a blocking layer that preventing the reversible electrochemical intercalations. In this regard, the research on new anode materials for MIBs is needed. Herein, we report aluminium (Al) doped silicon nanosheets (SiNS) as anode materials for MIBs. The SiNS have a thickness of 8 ± 3 nm with 6 μm of diameter and single crystalline structure. The SiNS are doped Al by in-situ and ex-situ doping process. The half cells are fabricated using Mg-Bi alloys (Bi 30 %) as the counter electrodes and the electrolyte is used Mg(TFSI)2 solution. The Al doped SiNS as anode show that the insertion of Mg ions into SiNS is feasible for more than a twenty cycles. It means that the very thin nature of SiNS provides a short diffusion path and Al-doping effects provides Si with defects which contribute to overcome the diffusion barrier issue at magnesiation of Si. The Al doped SiNS can be proposed feasibility assessment of anode materials in MIBs with these approach.

Resume : Rechargeable Aluminum Batteries (RABs) based on AlCl3-EMImCl ionic liquid electrolyte are among the most promising candidate for high energy storage devices/systems, due to the multivalent Al3+- ion intercalation property. However, the greatest hamper of the current development of RABs is the many contradictions in the literature. Reported results on active materials for cathodes and metallic current collectors suffer from misinterpretations and make further research difficult. We were able to show that as-synthesized cubic Co3O4 and Hausmannit Mn3O4 spinel-type materials are electrochemically inactive in AlCl3/ionic liquid RABs. The whole/entire performance is due to the reaction between the Lewis acidic electrolyte and the molybdenum (Mo) current collector. Since molybdenum is considered in the literature to be stable or rather its activity to be regarded as negligible, we could prove the opposite. Our results show three different oxidation states of the pristine molybdenum metal during the electrochemical process, which correspond to the work on the development of new novel current collectors for RABs. Since such side-reactions can show additional capacities of 150 mAh g-1 to 400 mAh g-1[1], we come to the result that it is necessary to exclude all possible Mo-sources in RABs. References [1] J. Shi, J. Zhang, J. Guo, ACS Energy Lett., 2019, 4 (9), 2124-2129.

Resume : In the era of green energy conversion and storage technology, design and development of bifunctional electrocatalysts for oxygen reduction reaction and oxygen evolution (ORR/OER) is a sensational issue. Thus, we have designed the ORR/OER bifunctionally active CeO2 nanospheres embedded NiO nanoflakes composite. The CeO2/NiO nanocomposite with the unique morphology is produced solvothermally, which shows an exceptional OER and ORR catalytic activity and outperforms the benchmark ORR catalyst Pt/C and OER catalyst IrO2. The CeO2/NiO nanocomposite exhibits a low onset potential of 0.80 V and 1.47 V (versus RHE) for ORR and OER, respectively. Furthermore, the small potential difference (i.e., ∆E) of 0.86 V between the half-wave potential of ORR and potential corresponding to the 10 mA cm2 OER current density represents the high efficiency of the CeO2/NiO nanocomposite as a bifunctional oxygen electrocatalyst. This outstanding bifunctional activity of the nanocomposite is attributed to the synergistic effect between CeO2 and NiO which create an increased number of oxygen vacancy defects as well as the more accessible active sites. The practical application of the CeO2/NiO nanocomposite is established with a homemade Zn-air battery (ZAB) that produces an open circuit voltage and a peak power density of 1.41 V and 105.0 mW cm−2, respectively with long-term cycling stability for 22 h.

Resume : The search for new energy storage materials is a key point in current materials science investigation. Bidimensional transition metal dichalcogenides (2D TMDs) such as MoS2 and WS2 are suitable candidates to deliver high capacitance and energy densities in pseudocapacitive or battery-like electrode materials with long operation lifetimes and low cost, due to the high surface areas and peculiar electronic properties.1 Their light-weight and suitability for incorporation into composite architectures, might make them also suitable active species into flexible energy storage systems.2 However, to maintain the wide active area of 2D TMDs when going from a colloidal ink, into which they are contained after liquid phase exfoliation (LPE), to a solid-state electrode architecture, it is necessary to develop effective strategies for the obtainment of porous scaffolds. The production of nanofibers through the highly versatile electrospinning technique is exploited by us to produce similar porous and 2D TMDs-integrating electrodes. To further overcome the low conductivity of these nanomaterials, either carbon nanotubes (CNT) are further incorporated into an electrospun fibrous polymer network, producing flexible free-standing films of a ternary 2D TMD/CNT/polymer composite, or a carbon fibers-based backbone is employed for the anchoring of the LPE 2D TMDs. The thus obtained nanostructured 3D scaffolds are characterized for their capacitive behavior to determine their potential for integration into energy storage devices.

Resume : Transition metal dichalcogenides (TMDCs) are widely popular in recent days as an electrode material for photoelectrochemical water splitting and supercapacitor due to their higher electrical conductivity compared to transition metal oxides (TMOs), large specific surface area, interlayer spacing for intercalation, low electronegativity, and excellent electrochemical redox sites. Two dimensional (2D) TMDs possesses effective electron transport and higher electronic conductivity compared to the oxides. There is electrochemical performance enrichment in TMDs which is due to their hydrophilicity and high electrical conductivity. The aim of this study involves development of efficient electrode based on TMDs viz., MoTe2 or MoS2 and their composites with TMOs or layered double hydroxides (LDHs) in dual mechanism study of photoeloectrochemical water splitting and supercapacitors. Herein, we demonstrate the growth of MoTe2 thin film polymorphic structure through metal organic chemical vapor deposition (MOCVD) on Si/SiO2 and ultrathin layer of MoS2 by atomic layer deposition and chemical vapor deposition thereby, the successful transfer of these TMDs structure on a flexible nickel (Ni) foam current collector for high performance electrochemical devices. A facile hydrothermal approach is used for the deposition of TMOs such as Co3O4 and NiCo2O4 and LDH structures like NiFe LDH. This work proposes design and development of TMD based electrodes having higher electrochemical/catalytic activity, high surface area and higher electronic conductivity due to the synergistic effect of aforementioned composites of materials for efficient electrochemical devices. The efficient electrode having dual electrochemical performance characteristic would pave the way to design and fabricate future energy materials to achieve sustainable energy system.

Resume : Waste heat discharged into the atmosphere is one of the largest sources of clean, fuel-free and inexpensive energies available. This presentation describes how organic ligands can be used to modify the charge density on the inner surfaces of ordered nanochannels in membranes made from anodised aluminium oxide (AAO) and cellulose. In the presence of a temperature gradient across these functionalised nanochannel membranes, ions with certain charges freely move through the pores, resulting in the generation of an electric current, i.e. an energy harvester. The nanochannels within AAO, cellulose and regenerated cellulose membranes were functionalised using a combination of oxidative, covalent and non-covalent chemistry approaches. Positively charged nanochannels, with different charge densities, were obtained with amino alkoxysilane ligands with one, two and three amino groups and with epoxy silane ligands. Furthermore, (2,2,6,6-tetramethylpiperidin-1-yl)oxidanyl (TEMPO), was used to oxidise primary alcohol groups in cellulose to carboxylic acid, generating negatively charged nanochannels under certain conditions [1]. Layer-by-layer (LBL) deposition, via electrostatic adsorption, of polyacrylic acid sodium salt (PAA) and branched polyethylenimine (PEI) polyelectrolytes was also achieved within the nanochannels of AAO membranes. The functionalised membranes produced were characterised by FTIR, XPS, contact angle measurements, SEM/EDX, TGA and cyclic voltammetry (CV). Initial electrical and thermoelectric measurements performed on the membranes demonstrated that surface functionalisation enhances ionic thermoelectric effects in the nanochannels. Further studies to explain this ionic thermoelectric effect enhancement, surface charge densities and zeta potential data are in progress. [1] Tian Li et al., Nature Materials, 2019, 18, 608.

Resume : Continuous research on improving the performance of existing materials and core technologies is in progress for the development of battery performance. The development of high-capacity positive electrode active materials and coating technology is an important part of the battery development because the capacity of the positive electrode at the conventional cell voltage mainly determines the energy density of the lithium-ion battery. Combined with electrolytic technology (e.g. functional high voltage additive or solvent), nickel-rich layered oxide (LiNi1−x−yCoxMnyO2 (NCM), 1−x−y≥0.5) cathode is charged to a voltage higher than conventional 4.2V and transported Increasing the amount of Li+ ions and electrons is an effective way to increase the capacity of the cathode. Nickel-rich layered oxides such as LiNi0.8Co0.1Mn0.1O2 (NCM811) can be expected as high-capacity cathode materials. Charging with a higher voltage than the conventional 4.2V further increases the reversible capacity, but it is difficult to manufacture due to the unstable cathode-electrolyte interface and structural deterioration. So, we report the combination of NCM811 positive electrode active material and nano-coatings of non-aqueous functional polyimide binder. It was possible to charge up to 4.4V even with an electrolyte without additives. This active material-binder combination inhibits metal dissolution and cathode deterioration and produces a reversible capacity higher than 200 mAhg-1. In addition, unlike conventional binders, it provides non-combustible properties and has the characteristics of higher energy and safer batteries. In addition, we report the development of fluorinated polyimide as a novel high-voltage binder. A novel high-voltage binder reduces the problem of cathode degradation the formation of a solid surface structure at the cathode. A full cell, composed of a fluorinated polyimide binder assisted lithium-rich layered oxide cathode and a conventional electrolyte without electrolyte additives, exhibits a capacity retention of 89% at the 100th cycle and a discharge capacity of 223-198 mAhg-1 at 55℃ and voltages of 4.7V. This is in contrast to the rapid degradation of cathodes coated with polyvinylidenefluoride binders.

Resume : Flexible LIBs have been of interest to researchers over the past decade due to their potential to power flexible, wearable, and implantable devices. These flexible batteries require new components that can not only handle the harsh conditions of operating LIBs, but also have flexibility, some degree of stretchability, and mechanical durability. It is well known that classical methods for synthesizing cathodes of LIBs can be achieved by applying slurries based on active materials, conductive carbon materials, binders and solvents onto metal plates. However, this type of electrodes have low flexibility due to their rigid structure and cannot meet the needs of flexible LIBs. Traditional lithium intercalation compounds for cathode materials, such as LiCoO2, LiMn2O4, LiNiO2, and LiFePO4, have achieved great success, but they face severe limitations in energy storage density and production costs associated with their use. Compared with other cathode materials, LiFePO4 has the advantages of competitive theoretical capacity, good thermal stability, high temperature overcharge resistance, low cost and environmental protection. However, pure LiFePO4 suffers from two major drawbacks, poor electronic conductivity and slow diffusion of Li+ through its one-dimensional channel, which affects its cycling performance and rate capability. Therefore, LiFePO4 should be modified by other materials to improve its electrochemical performance. Currently, the modification methods mainly include conductive material coating, cation doping, and increasing specific surface area. Among these methods, conductive polymer coating is an efficient and inexpensive method to enhance the electrical conductivity and electrochemical performance of LiFePO4. As one of the most promising polymers, polyaniline (PANI) possesses a series of excellent properties such as high electrical conductivity, high electrochemical activity, chemical stability and unmatched economic benefits. The electrochemical activity of PANI overlaps with the effective redox pair of LiFePO4. Therefore, PANI can not only be used as a conductive agent, but also a host material in the charging and discharging process, which can reduce the influence on the mass specific capacity of the material. In addition, carbon nanomaterials have inherent advantages in high specific surface area and electrical conductivity, which can improve the utilization of active materials and contact with electrolytes. Robust substrates based on carbon nanotube (CNT) and graphene (Gr) networks can be used to produce conductive and flexible binder-free electrodes, which are beneficial for the development of LIBs in the fields of flexibility and wearable device. We proposed a method to improve LiFePO4 cathodes. Herein, LiFePO4/CNT composites were synthesized using multilayer graphene as a "build-plate" substrate, in which LiFePO4 were interconnected by a bridging network of multi-walled CNTs. After that, the LiFePO4/CNT-Gr composite was coated with a thin polyaniline layer by the method of adsorbing double oxidants, and PANI with longer molecular chain and better performance could be obtained to form a core-shell structure. This work is hoping to improve cycle performance and rate capability of LiFePO4 in LIBs, and expand the application of LIBs in the fields of flexibility and wearable devices.

Resume : Lithium ion (Li-ion) batteries have been widely applied to portable electronic devices and hybrid vehicles. In order to further enhance performance, the search for advanced cathode materials to meet the growing demand for high-performance Li-ion batteries is significant. Iron disulfide (FeS2), an earth abundant and eco-friendly material, has widely been used as the cathode material for commercial primary lithium batteries at room temperature. However, over the past few years, rechargeable batteries have gained significant attention because of the ever-increasing demand for energy storage. FeS2 with a high theoretical capacity of 894 mAh/g, which is 3.2 times more than that of LiCoO2 (274 mAh/g), is considered to be a promising cathode material for rechargeable Li-ion batteries. However, the poor electronic/ionic conductivities of FeS2 and lithiation products, formation of soluble lithium polysulfides, and volume changes in Li/FeS2 rechargeable batteries limit their practical applications. In this study, a graphitic carbon encapsulated FeS2 composite was synthesized for high-performance lithium ion batteries by a simple and cost-effective approach via in-situ impregnation and sulfurization. The graphitic carbon shell formed by the carbonization of sawdust can improve the electrical conductivity and accelerate the conversion. The in-situ-formed FeS2 nanoparticles exhibited high specific capacitance and good cycling stability even at high C-rates. The composite exhibits a high reversible capacity and excellent rate performance.

Resume : Lithium sulfur battery (LSB), one of promising candidates for the next generation power source, possesses a high theoretical capacity of 1675 mAh/g and a high energy density of 2600 Wh/kg. Besides, sulfur is an abundant, inexpensive and environmentally friendly element, which is suitable for the large-scale production. However, LSB is still far from the practical application due to the known problems including insulating nature of sulfur, the dissolution of polysulfide intermediates and volume expansion of sulfur during charge and discharge processes. To overcome these limitations, many efforts have focused on the design of various structural matrices to encapsulate sulfur and developed new electrode active materials. In this study, modified hollow carbon spheres with controllable SiO2 content as sulfur host were investigated. The hollow structure not only can provide enough space to accommodate the active material, but also can relieve the volume changes during chare and discharge processes. SiO2, a polar material, can effectively adsorb polysulfides, and further enhance the electrochemical performance. When SiO2 content is 15 wt%, an excellent reversible capacity of 650 mAh/g after 100 cycles at 0.1 C-rate has been obtained. Therefore, the hollow carbon sphere with SiO2 is a promising cathode material for advanced high-performance lithium sulfur batteries.

Resume : Green hydrogen-based technologies have been regarded as one of the most promising solutions that can help to achieve the Net-Zero goal by 2050. One of the major challenges that can affect their broad upscaling and deployment is the efficient and sustainable clean hydrogen production and its subsequent storage. To address this problem, a novel idea combining the photoelectrochemical (PEC) water splitting with solid-state hydrogen storage in a single device is proposed. The concept will be tested in a PEC cell that comprises a photoactive anode, a hydrogen storage cathode and a weakly alkaline or seawater-based electrolyte. AB5- and A2B7-type intermetallic compounds (e.g., A: La, Mg, Y; B: Ni, Fe, Al, Co, Si, Sn), known for their applications in Ni-MH batteries, have been selected as a cathode material to engineer a model system. The thermodynamic and kinetic properties of the hydrogen sorption processes in the intermetallics have been characterized by pressure-composition-temperature (PCT) measurements. The electrochemical material performance, such as hydrogen storage capacity and cycling stability, have been studied by cyclic voltammetry, chronoamperomatery and galvanostatic measurements. The obtained preliminary results indicate that the overall performance of the selected compositions, i.e., ability to generate and store hydrogen via (photo-)electrochemical reactions are strongly dependent on the cathode design and compound chemical composition. The best performing hydrogen storage compound, with an optimized cathode architecture, will be integrated with a prototype PEC device, based on the earlier developed design. The proposed setup has been already successfully operated with a Pd-foil as a cathode and WO3 as a photoanode. The PEC cell has been characterized by relatively high Faradaic efficiency necessary to realize the concept proposed in this work. However, in contrast to the Pd foil-based cathode, the AB5-/A2B7-based electrodes are expected to offer much better cycling durability, with higher and reversible hydrogen storage capacity.

Resume : Recently, research on lithium-ion batteries has attracted attention. Attention is being paid to improving the performance of anode materials and cathode materials in lithium-ion batteries. Among them, we focused on anode material research using carbon nanomaterials. In this study, carbon nanowalls (CNW) and graphite slurries were used as cathode materials to use a large surface area. In order to enhance the adhesive force between the carbon nanowall and the current collector (copper foil), an intermediate layer was formed on the current collector by RF magnetron sputtering method for TiN. CNW grew on the intermediate layer TiN using a microwave plasma-enhanced chemical vapor deposition (MPECVD) system with a mixture of methane (CH4) and hydrogen (H2) gas. After that, the graphite slurry is casting on CNW to a uniform density and height and dried on a hot plate at 70 ℃. for 40 minutes. A lithium ion battery (5 types of coin cell parts) was manufactured as a working electrode of the anode active material manufactured for measuring the electrochemical properties. A field emission scanning electron microscope (FE-SEM) was used to confirm the surface and cross-sectional images of the negative electrode active material grown and synthesized from the carbon material, and a Raman spectroscope was used to examine the structural properties. In order to analyze the electrochemical properties of the lithium-ion battery manufactured by utilizing the prepared anode active material, impedance analysis, cyclic voltammetry (CV), and galvanostatic charge / discharge test were performed.

Resume : Over the last decade, concerns about global warming have stimulated the demand for green energy, which led to outstanding research interest focused on sustainable energy storage devices. Demand is more intense when it comes to healthcare applications. Supercapacitors are promising for small healthcare devices where long-term stability, fast charge-discharge rate, and high-power delivery are needed. The need for innovative solutions in healthcare applications allowed the newly minted field of edible supercapacitors. However, edible electrolyte design still remains a challenge, as the materials are limited to only natural or synthetic materials derived from food. Edible electrolytes need to be biodegradable and biocompatible while showing superior electrochemical performances. For biodegradability, materials with good biocompatibility and biodegradability should be used instead of toxic or non-toxic materials. In addition, biocompatibility is an essential parameter to ensure that innovative devices work adequately without causing adverse body reactions. The key to meet these challenges is to explore novel smart materials or functionalize the already existing ones. Herein, we successfully provide a route to design a biodegradable, and biocompatible supramolecular gel electrolyte that uses the promising advantages of zwitterionic soy protein. This gel electrolyte is used for the fabrication of an edible supercapacitor with electrodes made from carbon black and activated carbon. A specific capacitance of 2.3 F/g with an excellent rate capability up to 1Vs-1 is obtained from the supercapacitors fabricated with the gel electrolyte. The device showed capacity retention of 92% upon 10000 cycles. We believe that sustainable energy storage is expected to come to the fore in many application areas in the near future, especially with edible energy storage devices for healthcare applications.

Resume : Excessive emission of anthropogenic CO2 in our atmosphere is a major cause of global warming and environmental issues. Climate change is a significant global challenge and causes a serious threat to the planet. Several strategies have been proposed to reduce the emission of anthropogenic CO2, and to explore the use of CO2 as an abundant feedstock for the production of sustainable fuels. Thus, capturing CO2 using a porous polymer and the successful conversion into valuable chemical feedstocks is one of the vital solutions to mitigate this problem. Crosslinked porous polyimides (pPIs), a type of porous organic polymer (POP), offer a great potential for CO2 capture and conversion, owing to their porous nature and excellent redox behaviour.1, 2 Generally, pPIs are synthesised by polycondensation of dianhydride with multi-amines. However, incompatibility of solvents during the condensation yields lower surface area and limits total gas uptake. Here we describe in detail how we utilise the Bristol-Xian-Jiaotong (BXJ) approach,3, 4 using inorganic salts to tune the porosity and enhance the surface area by tuning the compatibility of the reaction solvent and the growing porous polymer. In this approach, we calculate the Hansen Solubility Parameters (HSPs) of our pPIs, and compare these with the HSPs of a wide range of common reaction solvents to find matching solvents for optimised synthesis conditions. Furthermore, HSPs can be tuned by inorganic salt additives (different ion sizes and concentrations), thus providing a useful method to fine-tune surface area and pore size distribution (PSD) of the polymers. The surface area and PSD of naphthalene-based pPIs acquired from non-BXJ polycondensation reactions have thus been optimised by calculating HSPs to find a suitable solvent for synthesis, and further optimised by salt additives. The surface area of BNPI-1 and BNPI-2 were enhanced from the published values of 16 and 15 m2g-1 to 846 and 613 m2g-1, respectively. The BXJ approach provides a simple route to tune the porosity properties in a controlled manner. Moreover, with the improved surface area and enhanced control over the PSD, CO2 uptake of naphthalene-based pPIs were increased to 14 wt%. Currently we are exploring the use of these naphthalene-based pPIs in the electrocatalytic reduction of CO2 into valuable chemical feedstock material. References 1. Y. Liao, J. Weber and C. F. J. Faul, Macromolecules, 2015, 48, 2064-2073. 2. B. B. Narzary, B. C. Baker, N. Yadav, V. D'Elia and C. F. J. Faul, Polymer Chemistry, 2021, 12, 6494-6514. 3. J. Chen, W. Yan, E. J. Townsend, J. Feng, L. Pan, V. Del Angel Hernandez and C. F. J. Faul, Angew Chem Int Ed Engl, 2019, 58, 11715-11719. 4. J. Chen, T. Qiu, W. Yan and C. F. J. Faul, Journal of Materials Chemistry A, 2020, 8, 22657-22665.

Resume : Nickel-rich layered LiNi0.97Co0.03O2 is a promising cathode material due to its high specific capacity. However, commercial application of this material is impeded by its rapid capacity degradation associated with structural instability. In this work, 0.02mol Al3 doped LiNi0.97Co0.03O2 cathode material is prepared by heat treatment of a mixture of stoichiometric amounts of nano-sized Al(OH)3 powders, co-precipitated Ni0.97Co0.03(OH)2 precursors, and LiOH·H2O. The results show that Al3 doping significantly improves the cycling properties of LiNi0.97Co0.03O2 cathode material. Under a voltage range of 3–4.3 V, 0.02 mol% Al3 doped LiNi0.97Co0.03O2 cathode material shows an initial discharge capacity of 225.5 mAh/g at 0.1C, with a capacity retention of 74.80% for subsequent 100 cycles at 0.5C at room temperature. In contrast, bare LiNi0.97Co0.03O2 shows a capacity retention of only ~69.8% under the same conditions, with an initial specific discharge capacity of 238.5 mAh/g. The improvement in cycling performance is attributed to stabilization of the layered structure by Al3 , mitigated migration of Ni2 to the Li layer, improved lithium diffusion kinetics and reduced lattice expansion/shrinkage during cycling. Stabilization of the layered structure by Al3 doping is further reflected by the observation of fewer cracks in cathode electrodes after prolonged cycling.

Resume : Melt electrowriting (MEW) is an electrohydrodynamic (EHD) 3D printing technology able to generate microfibers and precisely deposit them. This enables the printing of complex macrostructures, while controlling their micro features and micro behavior. In just a few years of development, the limits of MEW have been consistently pushed, allowing for growth in designs, features, and applications. However, there are still some limitations to overcome, as MEW requires high processing temperatures and the use of thermoplastics with high thermal stability. This hinders the processing of new materials and makes it difficult to expand the technology into new fields. To solve this, we recently propose a novel technique based on EHD processing of aqueous solutions, which conserve the potential for high-resolution microscale printing. For that, an open-source Voron 0.1 fusion deposition modeling (FDM) 3D printer was upgraded to extrude aqueous solutions through EHD forces and solidify the jet into a freezer collector. The new technology does not require complex components, avoids the use of toxic solvents, and simplifies the processing of new materials. By using a highly viscous silk aqueous solutions, it was possible to develop microfibers (30 µm) and accurately stack them in several layers, to generate multi porous structures with controllable microfeatures. Fiber’s size and stacking was varied to make pores with variable shape and size. Further, the control of ice crystals dimensions during freezing, and fibers drying process, make possible to generate fibers with variable porosity. As an attempt to reduce the environmental impact of batteries and push a transition towards more sustainable materials, the behaviour of multiporous structures for energy harversting was tested. For that, separator membranes were developed, and their electrochemical performance was measured. The control of the structures porosity was signalled as a key to controll the final performance of the batteries.

Resume : Over the past decade, rapid progress in consumer electronics and wearables, including health monitoring devices, has resulted in an extreme increase in electronic waste. The hazardous content and limited recyclability of these electronic devices is a major threat to the environment. Therefore, research and development on “green” electronics with non-hazardous materials and easy, low-cost manufacturing is a must. This requirement paved the way for an emerging new field; transient electronics. Transient electronics degrade with virtually zero waste at the end of their lifetime, which can be engineered depending on the need. There are numerous studies on transient electronics that demonstrate proof-of-concept and single-point applications. However, to achieve fully green electronics, all components must be designed and engineered to be transient, rather than focusing on a single component in an electronic system. Here, we have successfully fabricated transient supercapacitors, capacitive sensors and triboelectric nanogenerators by designing PVA-based layers, including electrodes, electrolyte, insulating layer, and encapsulate. Fabricated supercapacitors achieved a specific capacitance of 2.3 F.g-1 with excellent rate capability up to 3 V.s-1, which can be increased up to 10 V.s-1 when coupled up with additional cells. Moreover, flexibility of the transient supercapacitors is also demonstrated. Triboelectric nanogenerators are also fabricated and utilized in single electrode mode, which yielded a maximum voltage and current of 21.6 V and 4.6 µA, respectively. These transient devices then used to charge up small sized capacitors and used as self-powered sensors. Transient capacitive sensors are also fabricated utilizing all-PVA based layers. Sensitivity of 0.69 kPa-1 up to 22 kPa and 0.49 kPa-1 up to 44 kPa is achieved from these transient devices with promising response times. These flexible and transient capacitive sensors are used to monitor both small and large movements in different muscle groups on human body.

Resume : Silicon is an excellent storage material to replace the conventionally used carbonaceous anodes in lithium ion battery technology. However, the huge volumetric expansion and contractions during the cycling of the battery causes the structural deterioration of the anode. This decreases the energy density and reduces the storage capacity of the battery after longer charging and discharging cycles. The structural morphology of the Si can be modified to mitigate the effects of structural changes in the battery. Additionally, the performance of the battery can be enhanced by using suitable electrolyte to form stable solid electrolyte interface (SEI) and improve the stability of the electrode materials. In this study morphologically modified Si anode is used to reduce the effects of volumetric changes during cycling. Moreover, the electrochemical performance of the Si anodes is analyzed and compared in various combinations of electrolytes. The electrochemical properties are recorded by cyclic voltammetry whereas the corresponding structural and compositional changes are recorded by the TEM and XPS analyses. Porous Si with copper current collector is used as anode material. Porous Si was produced by electrochemical etching of single crystal Si in an HF containing electrolyte, producing 44% porosity with thickness of 7.5 µm. Five battery cells were cycled in electrolyte LP30 containing 1.0 M LiPF6 in a mixture of 50:50 ethyl carbonate and dimethyl carbonate (DMC). Additionally, electrolyte additives such as fluoroethyl carbonate (FEC) and vinyl carbonate (VC) were used in varying weight percentages in the base electrolyte LP30. In the half cell, porous Si was used as anode material, lithium metal as counter electrode, with 400 ml electrolyte poured onto the glass fiber separators and this assembly was enclosed in a stainless steel casing. The cyclic voltammetry was performed using computer controlled Astrol battery cycler for electrochemical characterisation. For structural and compositional analysis of the cycled porous Si anodes, HRTEM as well as Scanning TEM (STEM) was performed on Si samples in a Jeol-2100 equipped with an EDX detector. A direct comparison of the electrochemical performance and SEI compositions of the battery cells was observed for LP30, LP30+10FEC, LP30+2VC, LP30+5FEC+2VC and LP30+10FEC+2VC. The cyclic voltammetry measurements of LP30 with 10 wt. % FEC showed the lowest ionic and electrical conductivity whereas the addition of vinyl carbonate increased the electrical conductivity slightly. However, the most superior electrochemical performance was observed with 5 wt. % FEC and 2 wt. % VC in the base electrolyte of LP30. XPS and TEM results showed a presence of lithium, oxygen, carbon and fluorine in all the analyzed anodes with varying proportions. High fluorine and oxygen content was particularly evident in the SEI of the most samples, however, the elements were not homogeneously distributed in the cycled electrodes.

Resume : This work presents a systematic approach to formulating UV curable ionomer coatings which serve as ion exchange membranes when applied on porous substrates. Designing the ionomer precursor formulation requires bringing together compounds with drastically different properties into a liquid mixture. Hansen solubility theory was used to compatibilized main formulation components: acrylic sulfone salt (3-sulfopropyl methacrylate) and hexafunctional polyester acrylate crosslinker (Allnex, Ebecryl 830) otherwise non-mixable or mutely soluble. Among identified suitable solvents acrylic acid and acetic acid allowed for optimal mixing of the components and reaching the highest levels of sulfonic group content providing the desired ion exchange capacity. Interestingly, they represented a case of a reactive and non-reactive solvent since acrylic acid was built into the ionomer during the UV curing step. Properties of the two membranes variants were compared. Samples fabricated with acetic acid exhibit improved dimensional stability compared to the case of acrylic acid. Acetic acid allowed to lower area specific resistance (ASR) 6.96±1.03 Ohm*cm2, when compared with acrylic acid 14.38±1.41 Ohm*cm2 (in 0.5M NaCl). Both gains were achieved with no significant deterioration of the membrane selectivity 94 % and 97 %, respectively for acetic and acrylic acid preparation. Ion exchange membranes fabricated this way can be a cost effective alternative to Nafion® and similar thin ionomer film cation exchange membranes for application in energy storage and conversion (redox flow batteries, artificial photosynthesis cells, fuel cells) and separation processes (electrodialysis).

Resume : Solid-state electrolytes have become a hot topic for both scientific and industrial communities due to high safety and energy density. Notwithstanding these promising prospects, yet, with this type of electrolytes we encounter several challenges, majorily including limited charge transport over the solid electrode-electrolyte interface. This hindrance touches off electrode-electrolyte contacts as a result of the electrode volumetric changes, interface reactions and space charge layers driven by the difference in electrode and electrolyte electrochemical potential. One possible way to enhance the performance of solid-state electrolytes could be achieved by integrating of “Vitrimers”. Vitrimers, a class of covalent adaptable networks (CANs), derive their self-healable, shape memory, recyclability, and reprocessibilty properties from a covalent molecular network that can change its topology through molecular rearrangements, while preserving the total number of bonds in the network.(2) Therefore, vitrimers could restore the electrolyte-electrode contact, and destroy Li dendrites that could grow during battery cycling. Furthermore, thanks to their dynamic bonds, they can enhance the ionic conductivity.

Resume : Transition metal oxides (TMO) lead to an innovative direction for the development of materials for electrochemical energy storage due to their excellent stability. Zinc oxide (ZnO), a primary TMO, represents a green choice due to its abundance and biocompatibility. Surface modification and structural design represent the most traveled ways to improve the conductivity of zinc oxides-based electrodes. Indeed, nanostructures with many different shapes have been produced by both sophisticated and costly techniques as well as by means of cheap methods [1]. Here we focus on a cost-effective mass production of nanostars by means of Chemical Bath Deposition (CBD) in aqueous solution. Nanostars appear as 2D self-assembled bundles of crystalline ZnO nanostrips (sized 1oo up to 1000 nm), with clear hexagonal symmetry on the assembly plane (building 6-point stars). These novel nanostructures are deeply characterized by X-Ray diffraction (XRD), Scanning Electron Microscopy (SEM), Photoluminescence spectroscopy (PL) and electrochemical measurements (e.g CV, GCD), in order to evidence their structural, morphological, optical and electrical properties. The different preparative parameters, such as concentrations, thermal annealing and reaction time (growth kinetic) were deeply investigated. Specifically, with the kinetic nanostars with different arm lengths (range 80 nm up to 12 µm) have been obtained. We then tested and optimized the stars with different dimension as capacitors for Energy Storage applications. [1] Najib, S., Bakan, F., Abdullayeva, N., Bahariqushchi, R., Kasap, S., Franzò, G., Sankir, M., Sankir, N.D., Mirabella, S. and Erdem, E., 2020. Nanoscale, 2020, DOI: 10.1039/D0NR03921G

Resume : Given the wide capability of small positive ions (H and Li ) intercalation, WO3 represents a promising material for energy storage applications. In this scenario, nanostructured WO3 is extremely interesting due to its high surface-to-volume ratio allowing a high rate of charge transfer in supercapacitors with hexagonal crystal structure confirmed by XRD investigation and drop coated onto an appropriate substrate. A careful protocol for electrode realization, based on mass, thickness and morphology of WO3 based nanostructures is proposed. A large electrochemical study (employing by cyclic voltammetry and galvanostatic charge-discharge analysis) is performed to evaluate the charge storage capability, to describe and to model the storage process in terms of surface and diffusion-controlled mechanisms. The good pseudocapacitive characteristics of the realized WO3 nanostructures are hence proved by realizing an asymmetric supercapacitor (ASC) in which the as tested WO3 electrode acts as cathode and a graphene paper (GP) electrode is used as anode.

Resume : In this work, we consider the concept of water electrolysis, where OER and HER are temporally separated using a WO3 red-ox auxiliary mediator electrode. The proposed cell consists of a Pt wire as the working electrode and a WO3 auxiliary electrode. A aqueous solution of H2SO4 of different molarities is used as the electrolyte. In the first half cycle, the positive terminal of the external power supply is connected to the Pt wire and the negative terminal to the WO3 auxiliary electrode. The Pt electrode undergoes an oxygen evolution reaction, while the WO3 electrode undergoes an H intercalation reaction to convert WO3 to the HxWO3 electrode. In the second half-cycle, the polarity of the external power supply is changed, resulting in a hydrogen evolution reaction on the Pt wire and a H deintercalation reaction on the WO3 auxiliary electrode. The overall efficiency of the water splitting process, the efficiency of individual cycles and the stability of the WO3 electrode are discussed in the work. In addition, the efficiency of the process at high pressure and at different current densities is discussed. This work has been supported by the European Regional Development Fund within the Activity 1.1.1.2 “Post-doctoral Research Aid” of the Specific Aid Objective 1.1.1 “To increase the research and innovative capacity of scientific institutions of Latvia and the ability to attract external financing, investing in human resources and infrastructure” of the Operational Programme “Growth and Employment” (No.1.1.1.2/VIAA/3/19/466).

Resume : We have recently reported proton selective reversible redox reactions of zinc-terephthalic acid metal-organic framework (Zn-TPA MOF) in a Zn3(OH)4(TPA)･6H2O layered structure synthesized by microwave-assisted hydrothermal reaction. Therefore, it was indicated that the MOF has possibilities for the anode material of membrane-free aqueous semi-flow batteries. However, physical instability of the coated MOF electrodes and their low electrical conductivity made it difficult to evaluate the accurate electrochemical properties. Here, we have significantly improved the physical stability and conductivity of the electrodes in two ways: 1. by introducing a binder and blending conductive nanocarbon, and 2. by electrodeposition, so that reliable electrochemical measurements are made possible. From the SEM images of the composite electrode, the binder/conductive carbon particles filled the spaces between the MOF particles, resulting in a film with high adhesion. In the film obtained by electrodeposition, plate-like crystals grew dense and vertically on the FTO surface. In addition, the mechanical strength of the film was improved in the composite electrode and electrodeposited film, since no delamination of the film due to immersion in the electrolyte, which was observed in the electrode coated only with MOF. From previous studies, the redox reaction equation for Zn-TPA MOF (Zn3(OH)4(TPA)∙6H2O) was assumed to be an equation in which a proton compensates for the charge as a result of the two-electron redox of zinc in the structure. From cyclic voltammetry at 1 mV/s in 0.1 M KCl aqueous solution, the capacity utilization of the composite electrode and electrodeposited film was about 5 times higher compared to the electrode coated only with MOF. It is indicating that the improvement in conductivity due to the improved deposition or coating method led to a decrease in unreacted materials. For the composite electrode, galvanostatic charging / discharging tests were conducted at 0.5 A/g in 0.1 M KCl aqueous solution up to 100% state of charge. Up to the third cycle, Capacity Utilization was close to 100% and the capacity was 101 mAh/g. However, the fifth cycle, the capacity dropped significantly to 27 mAh/g. Total loss of MOF particles after the galvanostatic charging / discharging test was confirmed by SEM and XRD. From the above, it is expected that the assumed reversible reaction of MOF does not occur and that deposition and dissolution of zinc with structural decomposition occurs during charging and discharging, respectively. Unfortunately, the present work revealed that Zn-TPA MOF was not useful for its battery application. If MOFs are to be employed in batteries, it would be preferable to employ MOFs in which the redox active site is an organic linker rather than a metal node.

Resume : Nanostructured wood veneer with added electroactive functionality combines structural and functional properties into eco-friendly, low-cost nanocomposites for electronics and energy technologies. Here, we report novel conducting polymer-impregnated wood veneer electrodes where the native lignin is preserved but functionalized for redox activity and used as an active component. The resulting electrodes display a well-preserved structure, redox activity, and high conductivity. Wood samples were sodium sulfite-treated under neutral conditions at 165 ˚C, followed by the tailored distribution of PEDOT:PSS, not previously used for this purpose. The mild sulfite process introduces sulfonic acid groups inside the nanostructured cell wall, facilitating electrostatic interaction on a molecular level between the residual lignin and PEDOT. The electrodes exhibit a conductivity of up to 203 S m-1 and a specific pseudo-capacitance of up to 38 mF cm-2, with a capacitive contribution from PEDOT:PSS and a faradaic component originating from lignin. We also demonstrate an asymmetric wood pseudo-capacitor reaching a specific capacitance of 22.9 mF cm-2 at 1.2 mA cm-2 current density. This new wood composite design and preparation scheme will support the development of wood-based materials for use in electronics and energy storage.

Resume : Na β"-alumina has been primarily considered a solid electrolyte material for sodium high-temperature batteries, i.e., sodium-sulfur or sodium-metal halide batteries, due to its superb ionic conductivity, excellent thermal durability, and chemical stability with molten sodium. In recent research, the operating temperature of the batteries is getting reduced under 200oC to suppress cathode degradation and adopt an inexpensive polymer seal; so it is required to enhance the ionic conductance through the electrolyte further at the lowered temperature. The vapor phase conversion based on coupled diffusion of Na -O2- ions reported by A.V. Virkar's group suggests a promising way to improve the electrolyte conductance because it is able to shorten the conducting path by utilizing a thinner tape-casted α-alumina/yttria-stabilized zirconia(YSZ) composite as a precursor. Incorporating YSZ in the precursor is strongly demanded to promote the α-to-β" conversion with sodium oxide vapor in the deeper region from the surface; 30 vol.% of YSZ is generally used in recent works. However, the population of YSZ prohibits sodium ion transport through the electrolyte, so the conductance should be decreased in part. In this work, we have controlled the surface composition of the Na β"-alumina-YSZ composite to enhance its conductance at the Na electrode-electrolyte interface. The green sheets of α-alumina/30vol.% YSZ were tape-casted and layer-by-layer laminated, but the single sheet with 3 wt.% YSZ was employed as the surface layer. The laminated body was sintered and converted into the Na β"-alumina-YSZ composite. The less-zirconia zone is nearly 10% of the total thickness. Compared to the Na β"-alumina with 30 vol.% YSZ, this novel architecture gives a 13% increase in the ionic conductivity measured by the blocking electrode (33mS cm-1 at 200oC) and molten sodium reversible electrodes. Additionally, increasing YSZ contents at the surface support flexural strength enhancement with minimizing ionic transport decrease.

Resume : Commercially available lithium ion batteries (LIBs) show limitations for future large-scale applications, due to still low energy density, safety, slow charge/discharge rate and limited cycle-life. Battery recycling is also still an open problem, mostly bound to the use of toxic metals, thus research on new green and efficient electrode materials is advancing steadily. Among the proposed alternatives to commercial electrode materials, TiO2, sulfur and silicon are the most promising. These electroactive materials are green, abundant, low-cost and attractive for large scale production, thus identified as ideal alternatives to traditional LIB chemistries. Herein, composites consisting in graphene combined with these active materials were prepared, and their structural, morphological and electrochemical properties were investigated. Graphene employed for this work was obtained in large (grams) scale, through a thermal exfoliation of graphite oxide under dynamic vacuum, and is referred as TEGO (Thermally Exfoliated Graphite Oxide). We managed to decorate TEGO with different electroactive materials via different synthetic approaches. Once the composites were achieved, a characterization by means of powder XRD, Raman and TEM or SEM was performed; the electrochemical behavior was studied in half-cell configuration (CR2032 coin cells) via galvanostatic charge/discharge measurements. We found that graphene plays an important role, both as a substrate and as an efficient charge collector, thanks to its high electrical conductivity, contrasting the insulating nature of both TiO2, sulfur and silicon, thus improving specific capacity of the electrode. In particular, TiO2 composites were prepared by the solvothermal hydrolysis of titanium tetraisopropoxide in the presence of TEGO. The carbon scaffold was proven effective even by the addition of 1%, which achieved a stable and reversible capacity of above 180 mAh/g at C/5 and high charge/discharge capability. In addition, the structural evolution of the electrode upon cycling was investigated via operando synchrotron light diffraction, which highlighted the different Li intercalation processes. In the case of sulfur, the composite electrode materials were prepared following three different routes, namely physical mixing via ball milling, thermal infiltration and chemical decoration. The chemically decorated sample with 70 % sulfur loading was proven as the best candidate for lithium-sulfur batteries, obtaining a mean reversible capacity of about 525 mAh/g after 100 cycles. Finally, graphene was employed as a supporting material for Si-based batteries. In particular, silicon nanoparticles were produced by the disproportionation of SiO, obtaining a mean 4 nm crystallite size. The electrode composites were measured having an impressive starting capacity exceeding 7000 mAh/g, with a reversible capacity of 1150 mAh/g, retained after more than 70 cycles.

Resume : The discovery of the production of three-dimensional porous graphene material via direct laser writing on commercial plastic (polyimide), or other suitable precursors, in ambient conditions demonstrated an enormous potential for a wide range of applications, including flexible electronics, energy storage and sensing. The precise large-scale manufacturing of novel miniaturized and tailored devices can now be realised in a sustainable and inexpensive way with the use of laser, which, depending on wavelength, is able to convert a suitable precursor in graphene via photothermal or photochemical effect, or both. Nevertheless, graphene alone is not always able to provide the necessary performance of devices for specific applications, but it has been shown how metal or metal-oxide nanoparticle decoration of the graphene sheets can boost the specific capacitance of interdigitated supercapacitors, or greatly improve the sensitivity and selectivity in non-enzimatic biosensors. In this work some novel strategies for the one-pot synthesis of metal and metal-oxide nanoparticle decorated laser-scribed graphene will be discussed for the abovementioned applications. In particular, TiO2 (anatase) nanoparticle decorated laser-scribed graphene micro-supercapacitors outperformed pure graphene based devices, either in term of specific areal capacitance, reaching up to 13 mF/cm2, or in term of specific areal energy stored, up to 0.22 uW/cm2. On the other hand, Cu nanoparticles decorated laser-induced graphene-based electrochemical biosensors demonstrated superior sensitivity to glucose detection, down to few uM, also showing good selectivity against other biomarkers. Such findings strongly encourage the use of this technique for the large-scale production of novel inexpensive and environment-friendly laser scribed graphene based devices, which can be easily designed for the requested applications.

Resume : The global CO2 emission reduction demands an increasing usage of renewable energy resources. Along with sustainable energy employment, like Sun and wind, the need for reliable, cheap, and environmentally friendly energy storage technologies is becoming one of major unsolved challenges in the electricity grid. The Li-ion batteries are the dominant energy storage technology nowadays; however, material criticality and ecological issues are pushing us to look for alternatives. The aqueous Na-ion based batteries are recognized as promising candidates, already, especially in stationary energy storage technology. As a result, NASICON-structured NaTi2(PO4)3 (NTP) phosphate framework has attracted a lot of attention and remains one of the most studied negative electrode material. Despite considerable attention, the NTP electrodes’ degradation at aqueous electrolyte during long cycling procedure and self-discharge are the remaining unsolved problems for future applications. The pure NTP noticeably degrades when cycling rate is low at 1M Na2SO4 (aq.) electrolyte. On the other hand, it is known that material conductivity and crystal structure are changing by varying elemental composition of NASICON-structured NTP. For that reason, partial replacement of Ti4+ by Zr4+ or Hf4+ was studied. We present, in this work, the electrochemical properties and cycling stability in aqueous electrolytes results of NTP substituted with Zr(IV) or Hf(IV). The SEM, XRD, Cyclic voltammetry and Galvanostatic charge/discharge cycling analyses methods were used for the samples’ morphology, crystal structure and phase purity, and the electrodes’ stability assessment. Acknowledgement: This project has received funding from the European Regional Development Fund (Project No. 01.2.2-LMT-K-718-02-0005) under grant agreement with the Research Council of Lithuania (LMTLT).

Resume : Currently, the world is running towards an energy transition guided by an increasing need for energy storage systems, such as batteries and supercapacitors. This priority request must fit into a green economy context and meet sustainability requirements. In this work, we use industrial and agricultural waste to obtain optimized carbon based materials (biochars) as electrodes for supercapacitors (SCs). In particular, biochars have been produced by the pyrolisis of poultry litter, rice husk and melon peels at different heat treatment conditions or via hydrothermal synthesis in an autoclave. These products have been chemically activated with potassium hydroxide (KOH) via controlled thermal treatment under Ar flux. Morphological investigations have shown a huge increase in specific surface area, the presence of the hierarchical heterogeneous porosity of the materials and roughness due to the positive action of KOH, fundamental requirements for optimal SCs performance. SCs have been produced assembling two biochar electrodes supported on Ni-foams in a standard coin cell (CR-2032), separated by glass fiber soaked with the electrolyte. Different electrolytes have been tested, either aqueous, such as H2SO4, KOH, Na2SO4 solutions, in order to find those better matching the pores size of the carbon matrix. SCs devices have been tested with cyclic voltammetry at different voltage rates, in order to determine the specific capacitance and the electrochemical stability window, and galvanostatic charge/discharge measurements up to 5000 cycles to test the behavior upon cycling. We found that biochar-based supercapacitors show an almost ideal electrical double layer capacitance and electrochemical performance perfectly in accordance with that of state-of-the-art materials. In particular, biochar electrodes from poultry litter proved to be the most promising ones, showing a specific capacitance up to 229 F/g. The performance obtained on SCs are rather promising, disclosing to direct applications of a novel class of cheap and largely available waste carbon materials in the energy storage field, through the manufacturing of “all green” energy storage devices, giving a ‘’second life‟ to by-products and bringing benefits not only from a scientific point of view, but also from a virtuous purpose of waste minimization and valorization.

Resume : With electric vehicles reaching an all-time high in popularity, the safety of lithium-ion-batteries (LIB) is an increasingly pressing matter. However, various failure mechanisms such as overcharging, overheating, and decomposition reactions which take place during thermal runaway all lead to the emission of highly flammable and toxic gases. Therefore, the investigation of the chemical composition of the emitted gases is crucial for understanding the reactions that occur in the battery cell and assessing their impact on safety during battery failure. This knowledge can not only be used to produce safer batteries but can also help to improve their performance. The development and tailoring of electrolyte additive chemistries has been shown to improve cell performance by stabilizing the electrode/electrolyte interfaces. The most popular anode additives strengthen the solid electrolyte interface (SEI) by improving its mechanical integrity. The SEI, which is produced at the anode/electrolyte interface during the formation cycles, is composed of decomposition products that originate from reduction of the electrolyte. The reactions that lead to the SEI formation are also accompanied by gaseous side products, which can be analysed with gas chromatography-mass spectrometry (GC-MS). The GC permits the separation of the complex gas mixture, whereas the MS can be used to identify the separated analytes. In this work, the gaseous decomposition products of vinylene carbonate (VC) and fluoroethylene carbonate (FEC) as SEI forming additives were investigated with an operando GCMS. The operando method allows the volatile decomposition products to be monitored during electrochemical cycling. The operando technique not only allows the gases that evolve during SEI formation to be investigated, but also give valuable information on decomposition phenomena during overcharge. Our results show that the gas mixture evolving from the overcharge experiments contain a large amount of carbon dioxide due to the decomposition of the electrolyte solvents. In addition, various fluoroalkanes were observed, which can be attributed to the decomposition of the conducting salt lithium hexafluorophosphate (LiPF6). The findings are supported by cyclic voltammetry and additional electrochemical experiments. The author gratefully acknowledges the FFG (Austrian Research Promotion Agency) for funding this research within project No. 879613.

Resume : It is well known that rapid charging or cycling at low temperatures accelerates the degradation of Li-ion cells. The limiting factor for fast charging or low-temperature operation is lithium deposition on the anode side. It occurs when the negative electrode potential falls below the equilibrium potential of lithium. The deposited lithium can, e.g., react with the electrolyte and cause the formation of a new interfacial layer (SEI) or mechanically lose contact with the anode, creating the so-called dead lithium. As a consequence, the number of lithium ions involved in electrode reactions may decrease, resulting in a capacity fade. In addition, deposited lithium can affect the safety of the cell. Dendrites may pierce the separator, and the short-circuit can occur, causing a thermal runaway. It is necessary to optimize the charging procedures to effectively control lithium deposition when charging batteries at low temperatures or high current densities to avoid the issues. Many techniques have been described to monitor lithium deposition in lithium-ion cells. These methods can be divided into in-situ methods, mainly based on the analysis of cell operating parameters, and ex-situ methods, which are usually microscopic and require disassembly of the cell. In-situ methods do not require the disassembly of the battery. It is possible to infer the onset of lithium deposition by Using measurable parameters (e.g., voltage and current). So that such techniques can be successfully applied to BMS, which seems to be their most significant advantage. The objective of this work is to select the most universal and non-destructive methods for evaluating lithium deposition on the anode in the cells of different designs and composed of different materials. For this purpose, the two types of batteries were cycled under other operating conditions that lithium deposition preferably occurs - low temperature or high charging current. The application of numerous electrochemical methods and appropriate mathematical processing of the data made it possible. The conclusions on the evaluation of the lithium deposition phenomenon can be drawn under different operating conditions with the selection of best detection methods not limited to only one. This allows adjusting the best practices for cells in different charging regimes like constant current (CC) and CC-CV by simple basic parameters detection easily applicable in the BMS system.

Resume : Electrolyte additives contribute to the formation of solid electrolyte interphase (SEI), mainly on the anode side. There, additives can undergo reactions leading to products deposition on the anode surface. As a result, the formed layer is stable in contact with electrolyte components. On the one hand, it causes irreversible capacity loss during the first cycle. On the other, SEI allows for effective ion transport through the electrolyte/electrode interphase. Properly selected additives extend the shelf life of batteries and enhance battery performance and effectiveness of charge and discharge processes. SEI shows diverse characteristics depending on the interface properties like thickness, content, etc. Analysing the SEI itself is complex since many techniques must be implemented to characterize its composition correctly. Promising method is to analyse the electrolyte, which dissolves products of undesirable reactions of its components. Registering NMR spectra of electrolyte extracted from batteries can lead to identifying its content. Two electrolyte additives were tested: fluoroethylene carbonate (FEC) and 2,2-dioxide 1,3,2-dioxothiolane (DTD). Four electrolyte solutions were tested - base electrolyte consisted of commercial lithium salt in organic carbonates mixture, and subsequent electrolytes with a single or mixture of two additives. The three-electrode system measurement allowed for determining red-ox reactions in electrolytes and Li+ reduction potential. Two formation protocols were carried out to establish the effect of temperature on coin-cell type batteries and their properties, such as discharge capacity, the effectivity of charge-discharge cycles, and cell resistance. This work aimed to characterize the influence of different temperature formation protocols on Li-Ion batteries with selected electrolyte additives. DTD is preferable additive for cells in which formation protocols were carried out at 25 °C. In comparison, FEC has shown better performance in cells under formation at 40 °C. 1H NMR and 19F NMR spectra were registered for extracted electrolyte samples. Analysis of recorded spectra showed the effectiveness of the extraction method in observing signals originating from products of electrolyte decomposition. With comparison to recorded spectra for electrolytes before formation, we determined this method to be a promising tool in post-mortem analysis of cells, which can indicate their SoH and efficiency of electrolyte additives.

Resume : Transition metal nitride (TMN) thin films have been considered important electrode material to be used in energy storage based on their incomparable properties such as higher conductivity than oxides, hardness, inertness and catalytic or electrochemical activity. Nano-crystalline nitrides and their thin film based electrodes are used in supercapacitor for excellent electrochemical performance. Herein, we have deposited high quality thin films of transition metal nitride in controlled vacuum by using reactive dc- magnetron sputtering. Magnetron sputtering is a process that provides an extremely efficient and highly flexible way of building coating architectures with varying degrees of complexity. In this work, we prepared highly crystalline and uniform thin films with good adhesion on flexible and conducting substrate (SS-304) in Ar-N2 atmosphere. Field Emission Scanning Electron Microscopy (FE-SEM) revealed the film thickness and morphology of the films, while composition was confirm by the EDAX attached with FE-SEM. Surface topography and roughness was confirmed by Atomic Force Microscopy (AFM), while Cyclic Voltammetry (CV) was used to study surface electrochemical activity of the thin films. Crystal structure, phase orientation and elemental composition was confirmed by XPS (X-ray photoelectron spectroscopy) and XRD (X-ray diffraction). This study shows various aspects of TMN thin films based on their physio-chemical properties. Further, for practical demonstration developed electrodes were tasted in bending state to be used in flexible energy storage devices.

Resume : Lithium sulfur (Li-S) batteries are considered high-performance batteries for future energy storage devices, due to their high theoretical capacity, high energy density, abundance of sulfur and its friendly nature. However, several factors, such as the low efficiency of sulfur and the 'shuttle effect' of polysulphides, limit the development of Li-S batteries [1]. In order to limit these constrains, five cathode materials based on multidimensional architectures consisting of nanosulfur, graphene nanoplatelets (2D), carbon and multiwalled carbon nanotubes (1D) were synthesized in the present study via a simply preparation route. FTIR-ATR spectroscopy, TGA analysis and Scanning Electron Microscopy (SEM-EDX) investigations have been conducted in order to confirm the structure of the new materials and reveal the improvements beyond state-of-art.

Resume : Thriving for higher specific energies and energy densities, lithium-ion battery (LIB) research leans towards silicon as a high-capacity electroactive anode material. There are several approaches to limit the destructive forces within silicon particles, stemming from volumetric expansion upon lithiation. Lowering sizes or nano-structuring of silicon particles omit mechanical failures and enable a high cycle life. Additionally, a carrier component can be added to nano-structured silicon, reducing, or even compensating for the expansion. The use of porous carbon as carrier material is a successful approach[1,2] and porous ceramic materials could be a viable alternative. While conductive carbon promotes electrolyte decomposition on carrier surfaces, the non-conductive ceramic limits the loss to the active silicon part. Ceramics also show a very good high temperature stability and are non-flammable, which improves the safety of material handling and cells in operation. A widely employed group of porous ceramics are silica-based materials. Silica materials exhibit a high temperature stability at a low skeletal density of 2.19 g cm-3.[3] Nano-porous silica materials are mainly created by bottom-up processes in aqueous solution. The synthesis pH value determines if a loose or compact polymer network is formed. Porous structures are accomplished either by drying a loose network, or by forming a compact network around a removable template.[4-6] The templated approach is based on dissolved surfactant molecules which merge to micelles, given the appropriate solution concertation. These cylindrical micelles act as preferred polymerization sites for siloxanes, further building up the amorphous silica structure. The silica coated micelles further assemble to particles, which get separated from solution and dried. The template can be removed via solvent extraction or thermally, in a furnace process under presence of oxygen.[4,6] The choice for using silica in this contribution is based on the low bulk density, which helps minimizing the weight impact of the carrier material in the battery. The extensive control opportunities for the templated porous variant of silica particles also contributed to the selection. The work concentrates on controlling the three main properties of porous materials: pore diameter, pore volume and surface area. Influential synthesis parameters are determined and varied to gain knowledge on their specific impact on the porosity. The results may be used to target porosity of ceramic silicon carriers when the carrier requirements are established.

Resume : Hydrogen compressors based on metal hydrides (MH) represent an alternative technology to the conventional mechanical compressors used at refueling stations nowadays. The project Digi-HyPro (Digitalized hydrogen process chain for the energy transition), funded by dtec.bw – Digitalization and Technology Research Center of the Bundeswehr, aims at the development of a MH-compressor system as a key component for the energy transition of the mobility sector. MH-compressors offer the potential to drastically reduce the operating costs for providing high-pressure hydrogen.[1] Publications on experimentally investigated compressors show that a 2- or 3-stage setup can operate up to pressures of 350 bar compressed hydrogen gas while consuming heat of moderate temperatures below 150 °C.[2] Besides the number of stages, the performance of a metal hydride compressor depends on several design characteristics, mainly the selection of the hydride forming alloy, the enhancement of the heat transfer, and the reduction of thermal inert mass.[3,4] This work focuses on the comparison of different designs for 2-stage MH-compressors aiming at 350 bar refueling pressure for heavy-duty trucks. Steady-state energy and mass balances using theoretical material behavior are carried out. The performance and suitability for truck refueling and the compressor design efficiencies are discussed. References [1] Lototskyy, Mykhaylo; Davids, Moegamat Wafeeq; Swanepoel, Dana; Louw, Gerhard; Klochko, Yevgeniy; Smith, Fahmida et al. (2020): Hydrogen refuelling station with integrated metal hydride compressor: Layout features and experience of three-year operation. In: International Journal of Hydrogen Energy 45 (8), S. 5415–5429 [2] Yartys, Volodymyr A. et al. Metal hydride hydrogen compression: recent advances and future prospects. Applied Physics A 122 (2016): 1-18. [3] Bhogilla, Satya Sekhar; Niyas, Hakeem (2019): Design of a hydrogen compressor for hydrogen fueling stations. In: International Journal of Hydrogen Energy 44 (55), S. 29329–29337 [4] Bellosta von Colbe, Jose; Ares, Jose-Ramón; Barale, Jussara; Baricco, Marcello; Buckley, Craig; Capurso, Giovanni et al. (2019): Application of hydrides in hydrogen storage and compression: Achievements, outlook and perspectives. In: International Journal of Hydrogen Energy 44 (15), S. 7780–7808

Resume : Silicon anode is greatly promising candidates for high-capacity electrodes in lithium-ion batteries with due to its exceptionally high theoretical energy density. However, the silicon anode suffers from large volume changes during charge/discharge that leads to pulverization, resulting in rapid capacity drop. Here, water-processable polyimide (W-PI) precursor binder, poly(amic acid salt) (W-PAmAS), for high performance silicon anodes is prepared through a simple process and eco-friendly method. Compared to conventional organic solvent-based polyimide precursor, W-PAmAS is converted to W-PI at low imidization temperature of 150 ℃. The aromatic-based rigid backbone contributes to mechanical properties. In addition, introduction of carboxylic acid group of 30% can afford sufficient binding with silicon particles via chemical interaction, that binder effectively accommodate the volume expansion. This W-PI binder showed improved adhesion and excellent cycle stability (1883 mAh g-1 after 200 cycles).

Resume : Electronic textiles have received a lot of attention in recent years as a possible response to the current increase in the use of wearable electronics. Their use in a variety of applications, including health monitoring, sensing, and wearable electronics is promising. Textile-based flexible supercapacitors are key devices for these applications with their mechanical properties and charge storage capabilities. Herein, high-performance all-solid-state wearable asymmetric supercapacitors (ASCs) are prepared based on 2D cobalt metal-organic frameworks and iron sulfide/graphene (FexSy-G NCs) composites on carbon textiles as the positive and negative electrodes, respectively. The electrode materials are biocompatible, and the simple solution-based production route is environmentally friendly. High reversibility coupled with a high specific capacitance of 263 mF.cm-2 is achieved from the Co-MOFs. As the negative wearable electrodes, iron sulfide-graphene nanocomposites (FexSy-G NCs) are developed to utilize the inherent conductivity and exceptional pseudocapacitance of metal sulfides. A specific capacitance of 500 mF.cm-2 is obtained from these electrodes. The combination of these two electrodes into a quasi-solid-state textile-based supercapacitor device, assemble strategies for long-lasting devices and their detailed electrochemical analysis will be presented. This work was supported by The Scientific and Technological Research Council of Turkey (TUBITAK) under Grant No:119N344.

Resume : Poly (amic acid) salt (PAAS), ecofriendly polyimide (PI) precursor, was synthesized from 3,3′,4,4′-Biphenyltetracarboxylic dianhydride (s-BPDA) and p-Phenylenediamine (p-PDA) in an aqueous solution with 1,2-Dimethylimidazole (DMIZ) acting as an organic base as well as an imidiation catalyst. The synthesized PAAS aqueous solution was converted to PI film by thermal imidization after producing gel film by the doctor blade coating method. To investigate the thermal imidization behavior of PAAS, the chemical and structural properties of the film were observed at the various temperatures corresponding to the steps of solvent evaporation, imidization, and annealing. It was confirmed through Thermogravimetric analysis (TGA) and TGA-gas chromatography (TGA-GC) analysis instruments that the PAAS film showed the maximum weight loss at 142 °C and was completely converted to PI film at 350 °C. Water-based PAAS was completely converted to the PI at the lower temperature(150 ℃ – 250 ℃) due to the presence of DMIZ compared to that of poly (amic acid) (PAA) that is the conventional PI precursor synthesized in an organic solvent such as NMP. We will present the electrical and mechanical properties of ecofriendly PI films prepared by aqueous poly (amic acid) salt.

Resume : Ordered Double Transition Metal MXenes (DTMs) and their MAX phases are a more recent addition to the rapidly growing MXene family of 2D materials. The few reports published on the electrochemical charge storage properties of DTMs suggests that they perform much better than their mono metal counterparts. This is true for both ordered and solid solution DTMs . Despite the theoretical predictions on the stability of a number of double transition metal MAX phases, only a few have been synthesized and etched into their corresponding MXenes. In attempt to scale up the synthesis and processing of DTMs, we present the synthesis and structural studies of ordered Mo2Ti AlC2, Mo2Ti2AlC4, Cr2TiAlC2, Cr2Ti2AlC3 and solid solution Ti2NbAlC2 MAX phases and their etching into corresponding MXenes. In-situ high temperature XRD data collected on the admix of activated metal powders was used to optimize and model the MAX phase synthesis in high temperature tube furnace. Electrochemical studies such as CV, EIS and CCD of the DTMs compared with Ti3C2Tx will be presented and discussed.

Resume : Activated carbon is an example of a disordered material which shows different properties depending on its atomic structure, which in its case can be manipulated by changing the activation state. To fully understand the relation between changes in atomic structure and material properties in materials like activated carbon and other disordered battery materials, a precisely description of the atomic structure is needed. Often the atomic structure are described via pair distribution functions (PDF), obtained from X-ray diffraction measurements. However, PDFs do not unambiguously describe one atomic structure, but the same PDF can belong to different atomic structures with different angular atomic arrangements. A way to measure the angular arrangements of the atomic structure is to analyse angular correlations of Scanning Electron Nanobeam Diffraction (SEND) pattern. Our research is aimed to further establish the usage of the analysis of SEND pattern to obtain information about angular arrangements in disordered materials. Thereby, our work is focused on making correlation analysis more robust, by for example establishing pre-treatment of the data before the analysis to reduce noise, or investigating conditions under which higher scattering orders can be analysed. Furthermore, general study of the results of correlation analysis of SEND pattern is driven forward by for example investigating the influence of the material thickness on the results. With our work we will contribute not only to the clarification of the atomic structure of activated carbon, which we use as model system, but we will also provide tools for the structure analysis of other battery materials.

Resume : Transition metal oxides' abundant availability, low-cost, high theoretical specific capacitance, and environmental benevolence make them the most attractive electrode materials for supercapacitors. Herein, we have synthesized a stable n-type three-dimensional (3D) iron oxide (Fe2O3) nano-cubes using a facile one-step hydrothermal approach through the oxidation of iron chloride salt in a high pH environment. These synthesized nano-cubes were confirmed by the X-ray diffraction pattern (XRD), Field-emission scanning electron microscopy (FE-SEM), Transmission electron microscopy (TEM), and Energy dispersive X-ray analysis (EDX) results. The as-obtained hematite (α-Fe2O3) nano-cubes are characterized structurally and electrochemically, suggesting good thermodynamic stability with high reversible redox activity. A good geometrical structure with monodispersed structures is obtained. The electrochemical performance of the nano-cubes was evaluated by using cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), and electrochemical impedance spectroscopy (EIS) measurements. The cyclic voltammograms obtained for the iron oxide nanocubes-based electrodes suggest a typical pseudocapacitive-like behavior. The nano-cubes exhibit a wide potential window with a high specific capacitance value of ~ 170 F/g at a scan rate of 2mV/s with 83 % capacitance retention rate after 1000 redox cycles. High specific capacitance value, stable cycling, and facile preparation make hematite (α-Fe2O3) nano-cubes an excellent material for use as supercapacitor electrodes.

Resume : The aim of the work is the new way of lithium amide synthesis. The synthesis was performed with the use of two different methods. Both are associated with the reaction of pure metallic lithium with a mixture of hydrogen or nitrogen. In the first case, reactive milling was applied. In the second method, lithium was heated under a reactant mixture under static conditions. All material features were examined with X-ray phase analysis, differential scanning calorimetry, thermogravimetric analysis, and mass spectrometry. Obtained results were analyzed to find correlations between technological process parameters and synthesized materials' properties. Attempts to obtain the compound by reactive milling were unsuccessful due to the high plasticity of the material and the occurrence of cold welding, which prevented further movement and operation of the milling medium. On the other hand, using a system of high temperature and elevated pressure results in obtaining a material in which the lithium amide phase was identified. Crucial in terms of the properties of obtained samples are process conditions (pressure, temperature, time of reaction occurrence, and heating scheme). The decomposition of the compound strongly depends on the phase composition and is limited by the presence of lithium hydride, which does not decompose under such conditions. During the lithium amide decomposition, the ammonia is released. As a result, in most cases of the analyzed samples, the material obtained is characterized by a slight mass loss caused by the presence of lithium hydride in the structure. The purity of the material and the homogeneity of the phase composition are crucial for the efficient decomposition of the compound and the possible use of such a method in practice.

Resume : Metal-organic framework (MOF) is a supramolecular coordination system composed of metal ions coordination, nodes, and organic ligands. These are to afford adequate redox sites for enhanced ion diffusion. Using MOF as a template to fabricate a novel platform can deliver large specific surface areas and abundant oxidation-active sites to augment electrical conductivity. The composite's unique morphology can significantly shorten charge transport paths to alleviate electron transport and diffusion. The incorporation of vanadium in the intermediate leads to a broad impact on the morphology and the electrochemical energy storage of the ZIF-67 or Cobalt-Imidazolate matrix. The DMSO is a solvent for fabricating the vanadium cobalt oxide composite. Imidazole is used as an initial organic linker to initiate the formation of ZIF-67 in DMSO. Then the vanadium ion is integrated into the same material matrix. In this study, the integration of annealing plays a pivotal role in alleviating electrochemical storage. XRD prominently affirms the corresponding MOF crystal peaks. The high intensified mountains symbolize the cobalt vanadium oxide phase and confirm ZIF-67 formation. The FTIR spectroscopy investigation delineated the proper presence of cobalt, vanadium, carbon, and nitrogen. The FESEM morphology illustrated the dissimilar structure and was likewise involved in the charge storage. The morphology significantly impacts surface-dependent charge storage with having introduced porosity. High-temperature annealing also consists of the crystal orientation of the bi-metallic MOF matrix and creates porosity on the effective surface area. The Co-MOF-V oxide composite is thoroughly investigated in three-electrode arrangements for analyzing the electrochemical charge storage in 2M KOH as working positive electrodes in -0.2 to 0.6 V window w.r.t the SCE as reference. The specific capacitance value is obtained at 540 F/g at a 2mV/s scan rate. Furthermore, the charge-discharge analysis of the composite delineated an admirable discharge time at 3mA/cm2 current density. It portrayed 352 F/g specific capacitance, leading to higher specific energy and specific power of 17.02Wh/kg and 933.53W/kg. The Nyquist plot corroborates that the electrode resistance, electrode-electrolyte interfacing resistance, and the value of diffuse layer resistance are significantly less. This study can bestow a more significant pathway of ion transportation from the electrolyte to active electrode material that abetted to the superior storage using complete morphology. The transition metal's variational oxidation state directly contributes to this ZIF-67 composite's pseudocapacitive charge storage process. Alternatively, comparable analysis is directed over anode material lignocellulose-derived activated porous carbon. In the potential window of -1 to 0 V w.r.t, it is depicted that the Ag/AgCl electrode is in 2M KOH. The gained specific capacitance from the cyclic voltammetry analysis is 426 F/g at a 2mV/s scan rate. Besides, the carbon depicted admirable discharge time at 0.5A/g current density and portrayed 565 F/g specific capacitance. The specific energy and power of 78.47Wh/kg and 282W/kg at the same current density. The high active surface area integrated with pores significantly derived from the MOF matrix strengthens charge storage. Furthermore, the asymmetric supercapacitor storage is made up. That system works upon 0 to 1.4V windows. The attained areal capacitance is 0.54 F/cm2, and volumetric capacitance is 0.68 F/cm3 in the current density of 4mA/cm2. The Ragone plot shows its perfect positioning in the region of asymmetric storage. This ASC system delineated coulombic efficiency at 82% of capacitive retention at 79% after the 10,000 long cycle stability study. The electrochemical impedance spectroscopy analysis shows that the interfacing and electrode resistance diffuse layer resistance is significantly lesser and upwards.

Resume : The long-term instability of liquid electrolytes in Lithium-ion batteries may results in safety issues and its energy density should be increased for high energy demanding applications. Lithium metal batteries (LMBs) have been intensively investigated to fulfill these needs. However, the progress of liquid electrolytes for LMBs has been slow, with barriers, including undesired lithium dendrite growth and unstable solid electrolyte interphase formation. Solid polymer electrolytes (SPEs) offer a possible solution to these drawbacks. Liquid crystals (LC) have been proposed to improve the performance of SPEs. They are able to self-organize into mesophases in which well-defined ion pathways emerge at the nanoscale. Furthermore, the liquid crystalline phase can be used as to homogenize the lithium surface and suppress the growth of lithium dendrites. In addition, LC might display self-healing properties, extending the lifetime of the battery. In this work the N-(4-Methoxybenzylidene)-4-butylaniline (MBBA) and 4-(trans-4-Amylcyclohexyl)benzonitrile (CBN) are used to prepare SPE where different approaches are tested. The first approach is based on the reorganization of the PEO-chains since they are mobile and respond to stimuli. LC show a self-organization in the liquid crystalline state which can help the organization of the PEO-chains and therefore improve its ionic conductivity. For this, LC are added to the mixture of the SPE as an additive. For the second approach, an interlayer (5 μm) of 1 molar LiTFSI in LC is placed between the SPE and the current collectors, as illustrated in Figure 1. Considering the self-organization of the LC, the interlayer can be used to homogenize the deposition of lithium, suppressing the lithium dendrites. To validate this, lithium stripping plating experiments are performed and cells with and without interlayer compared. However, the ionic conductivity is expected to be lower since the Li-ions have to cross multiple interphases and the solution of LiTFSI is found to be low conductive, e. g. for MBBA 3*10-7 and CBN 2*10-5 S*cm-1 at 40 °C. The ionic conductivity of the SPEs using LC as additive and interlayer are evaluated with symmetric cells composed of Cupper, for each system PEO/LiTFSI is measured as reference.