Battery and energy storage devices: from materials to eco-design

Resume : There is a significant push within the Li-ion battery world to reach greater energy densities and safety characteristics. Solid polymer electrolyte (SPEs) Li-ion batteries offer enhanced safety via reduced material flammability and resistance to lithium metal dendrite formation in contrast to classical liquid electrolyte Li-batteries batteries. However, the safety benefits of SPEs are tempered by reduced Li conductivity when contrasted to liquid systems, and requires in most cases operation at elevated temperature to ensure the highest possible conductivity. To date, polyethylene oxide (PEO) is still the most studied system. However, despite significant effort, PEO cannot be easily used above 4 V, due to vulnerability to oxidation and degradation caused by Li salt and electrode by-products under operating conditions. This has led to many alternative polymers being tested, ranging from simple commercially available polymers to complex custom prepared systems. These include, but are not limited to polyesters, polycarbonates and polynitriles, with more exotic systems looking at co-polymers and composite SPEs. This study will look at the preparation of novel plasticiser free polyethyleneimine (PEI) co-polymers, from monomer to SPE, and subsequent testing and benchmarking against PEO systems. Performance will be studied using a flexible cell solution, that allows simultaneous, in operando measurement of SPE thickness under electrochemical characterisation, at a range of temperatures. This allows for accurate determination of SPE conductivity and Li transference number at different temperatures.

Resume : The need for sustainable mobility leads to a growth of the market of electric cars. At this moment, lithium-ion batteries are the most suitable technology due to their high gravimetric and volumetric energy density. In all roadmaps for battery development, solid-state batteries are the next step after advanced lithium-ion batteries. They offer the potential to significantly increase the energy density, combined with a higher safety due to the absence of a flammable liquid electrolyte. During the last years, research on solid-state batteries has significantly increased, but still faces many challenges, such as the development of a high performant solid electrolyte, the integration of the cathode active material with the solid electrolyte, and the integration of the lithium metal anode which is needed to obtain the predefined energy densities. The polymeric backbone eutectogel (P-ETG) is a hybrid solid-state electrolyte in which a Li-ion conducting deep eutectic solvent is confined within the polymeric backbone. Such an electrolyte allows the combination of the processability advantage of polymers with the high Li-ion conductivity of liquid electrolytes, thus overcoming the primary disadvantages of solid polymer electrolytes. We introduce a P-ETG compatible with high-voltage cathode materials. The (electro)chemical compatibility between the cathode and electrolyte is studied by means of (physico)chemical characterization methods, such as XRD, FT-IR, and ICP-OES. The electrochemical properties, such as ionic conductivity and stability window, are probed by electrochemical impedance spectroscopy and voltammetry experiments. The galvanostatic cycling behaviour of the Li|P-ETG|NMC-622 cell is assessed at several (dis)charge rates. This project receives financial support from VLAIO (Baekeland project) and Umicore. C. Sun, et al., Nano Energy, vol. 33, pp. 363?386, 2017 J. Janek, W. G. Zeier, Nature Energy, vol. 1, no. 9. pp. 1?4, 2016 A. Manthiram, et al., Nat. Publ. Gr., vol. 2, 2017 B. Joos et al., Chem. Mater., vol. 32, no. 9, pp. 3783?3793, 2020

Resume : The high demand for portable energy storage is driving the development of new, more efficient and safer portable energy storage systems. A lithium-sulfur battery is based on a lithium metal anode and an elemental sulfur cathode. It is a very promising system on paper as it has a very high theoretical energy density. In addition, sulfur is an inexpensive, abundant, non-critical and non-toxic raw material. On the other hand, lithium-sulfur batteries with conventional liquid electrolytes suffer from several problems preventing them from being commercialized today. The development of so-called "all-solid-state" lithium-sulfur batteries with the use of a highly conductive solid electrolyte (SE) could resolve these difficulties(1). In particular, solid sulfide electrolytes (SSEs) have received increasing interest in recent years due to their promising ionic conductivities around 10-2-10-3 S/cm(2) and their ductility. However, while it solves the problems associated with liquid electrolytes, the all-solid-state system also presents a number of specific challenges. One major challenge of the all-solid-state systems is the study and the control of the interfacial issues, in particular of the SE/Li metal anode interface. Indeed, stability issues of the sulfide-based electrolytes with Li metal may be encountered, as being thermodynamically unstable against lithium metal, as well as the possible growth of lithium dendrites through the solid electrolyte separator (3,4). Since both of these phenomena can severely impact the performance and safety of the battery (poor electrochemical stability of the SE against Li metal leads to decomposition of the SE thus increasing the impedance; growth of lithium dendrites leads to short-circuit of the battery), they must be understood and suppressed. In this work, we study two sulfide electrolytes: argyrodite-type crystalline Li6PS5Cl and glass-ceramic Li7P3S11. In order to assess and compare their stability against lithium metal, Electrochemical Impedance Spectroscopy measurements were carried out over time on symmetric Li/SSE/Li cells, as well as post mortem observations. While the impedance response is multiplied by a factor of 10 within 150h in the case of Li7P3S11, it remains relatively stable for argyrodite type cell. The nature of the decomposition products of the two electrolytes with lithium have been characterized post mortem, and allow a better understanding of this difference in stability. We demonstrate that in the case of argyrodite, the decomposition products limit the further reaction of electrolyte with lithium, whereas they promote the propagation of the decomposition reaction of Li7P3S11. [1] Wang, HangChao, Xin Cao, Wen Liu, et Xiaoming Sun. 2019. « Research Progress of the Solid State Lithium-Sulfur Batteries ». Frontiers in Energy Research 7: 112. [2] Busche, Martin R. et al. 2016. « In Situ Monitoring of Fast Li-Ion Conductor Li 7 P 3 S 11 Crystallization Inside a Hot-Press Setup ». Chemistry of Materials 28(17): 6152?65. [3] Yue, Junpei, Min Yan, Ya-Xia Yin, et Yu-Guo Guo. 2018. « Progress of the Interface Design in All-Solid-State Li-S Batteries ». Advanced Functional Materials 28(38): 1707533. [4] Wu, Bingbin et al. 2016. « Interfacial Behaviours between Lithium Ion Conductors and Electrode Materials in Various Battery Systems ». Journal of Materials Chemistry A 4(40): 15266?80.

Resume : In recent years, there has been growing interest in ionic liquids (ILs) electrolytes since their superior thermal and electrochemical stability with respect to conventional organic electrolytes [1]. The need of incorporating ionic liquid into solid state energy storage applications has led to the development of iongels materials. This novel class of materials combines the unique electrolyte properties of ILs with the superior mechanical properties of polymers [2]. In this work, a simple method to prepare a mechanically robust iongel films is demonstrated. Fast (< 1 min) UV photopolymerization of poly(ethylene glycol) diacrylate in the presence of a saturated 42%mol solution of sodium bis(fluorosulfonyl)imide in trimethyliso-butyl phosphonium bis(fluorosulfonyl)imide was employed to prepare versatile taskspecific iongel electrolytes for application in two emerging solid state energy storage devices: namely sodium metal batteries and sodium oxygen batteries. The iongel electrolytes showed high ionic conductivity at room temperature (?10?3 S cm?1) and tuneable storage modulus (104? 107 Pa). The high salt concentration of the gel electrolyte (42% mol) was beneficial for battery performance, Na/iongel/NaFePO4 full cells delivered a high specific capacity of 140 mAh g?1 at 0.1C and 120 mAh g?1 at 1C with good capacity retention after 300 cycles. In addition, preliminary results in sodium oxygen batteries showed remarkable capacity of 0.285 mAh cm?2 at a discharge current of 0.1 mA cm?2. These results suggest the feasibility of solid state design based on iongel materials for next?generation energy storage and conversion applications based on sodium metal electrodes. References: [1] A. Fdz De Anastro, L. Porcarelli, M. Hilder, C. Berlanga, M. Galceran, P. Howlett, M. Forsyth, D. Mecerreyes, ACS Applied Energy Materials 2019, 2 (10), 6960-6966. [2] M. Forsyth, L. Porcarelli, X. Wang, N. Goujon, D. Mecerreyes, Accounts of Chemical Research 2019, 52 (3), 686-694

Resume : Ion conductive ceramics play an important role in industries and manufacturers due to their wide applications on energy storage devices. Many synthesis approaches to prepare ceramics have been developing rapidly in the few decades. One of the most simple and easy ways to prepare ceramics was using the solid-state reaction method and varying calcinated temperatures. In this works, we developed ion conductive ceramics, microstructure analysis by XRD and SEM, and conductivity measurements. Our important finding was an improvement in the performance of microstructures, crystallinities and conductivities by changing calcinated temperatures. The raw materials of Na3.3Zr2Si2PO12 were wetly mixed for 24 hours and were dried overnight. Na3.3Zr2Si2PO12 powders were then calcined at three different temperatures, that are 1150°C, 1175°C, 1200°C, and 1225°C for 12 hours. The calcined powders were compacted at 250 MPa and then were sintered at 1100°C for 10 hours. On the pellets obtained, EIS measurements were carried out to determine the ion conductivity.

Resume : The strong demand for advanced high-energy-density batteries for the fast-growing electromobility sector necessitates not only the design and development of new electrode/electrolyte materials but also their sustainable synthesis and fabrication. In this context our research focuses on electrode materials made of abundant elements and have high-energy density potential because of their either high theoretical capacity, high-charge voltage, or multi-ion activity as is the case of lithium iron orthosilicate (Li2FeSiO4/LFS) [1,2], lithium cobalt phosphate (LiCoPO4/LCP), and titanium niobate (TiNb2O7/TNO) [3]. Despite however, the promise of these materials for high-energy density gains, there remain significant inherent structural limitations as is energy storage beyond one Li, poor Li-ion intercalation kinetics, electrode/electrolyte interfacial reactivity and complex phase transitions resulting in poor capacity retention. Herein, we report on controlled solution synthesis and deposition of the above nanostructured materials, their mechanochemical and thermal annealing, as well as their composition & interfacial engineering opening new pathways towards realization of their full high-energy density potential. Meanwhile, we have developed a low-temperature sustainable synthesis method allowing for production of cubic nanostructured garnet-type ceramic electrolyte for all-solid-state battery systems. Work is underway for low resistance interfacial integration of garnet with TNO anode and LCP cathode. Acknowledgments: This work is supported by NSERC Canada, Hydro-Québec, and McGill?s Sustainability Systems Initiative (MSSI). References: [1] Yan Zeng et al., Defect Engineering of Fe-Rich Orthosilicate Cathode Materials with Enhanced Li-Ion Intercalation Capacity and Kinetics, ACS Applied Energy Materials, 2020, 3, 675?686 [2] Majid Rasool et al., PEDOT Encapsulated and Mechanochemically Engineered Silicate Nanocrystals for High Energy Density Cathodes, Advanced Materials Interfaces, 2020, 2000226; DOI: 10.1002/admi.202000226 [3] Marianna Uceda et al., Nanoscale Assembling of Graphene Oxide with Electrophoretic Deposition Leads to Superior Percolation Network in Li-ion Electrodes: TiNb2O7/rGO Composite Anodes, Nanoscale, 2020, 12, 23092?23104

Resume : Inorganic solid-state batteries (SSBs) are promising candidates to replace liquid-electrolyte-based lithium-ion batteries (LIBs) for application in electric vehicles, mainly due to potential improvements in safety and energy density. Lithium thiophosphates stand out among the conceivable superionic solid electrolytes, as they show the highest room-temperature ionic conductivities achieved to date. However, their narrow stability windows makes them prone to degradation. Overall, thiophosphate-based SSBs have been reported to suffer from impedance growth and capacity fading due to side reactions at the interfaces during battery operation, thereby emphasizing the need for protective coatings. The beneficial effect of cathode materials coatings has been reported in a large number of studies, with the majority focusing on Li-containing ternary oxides applied by wet-chemical methods. While versatile, cost-efficient and easy to implement, such methods provide only limited control over the coating thickness and morphology. In contrast, atomic layer deposition (ALD) allows preparing conformal nanocoatings on substrates with complex surfaces. ALD has been widely applied in the field of LIBs, but few examples exist on the use of ALD-functionalized electrode materials in bulk-type SSBs. In this contribution, we report on the coating of LiNi0.85Co0.1Mn0.05O2 (NCM-851005) cathode material with HfO2. Specifically, we describe the preparation of HfO2-coated NCM-851005 by ALD of tetrakis(ethylmethylamido)hafnium(IV)/O3. In addition, the positive effect of the nanocoating, especially after annealing, on the cycling performance of NCM-851005 in high-loading SSB full cells with argyrodite Li6PS5Cl solid electrolyte is highlighted.

Resume : Sodium-seawater batteries (Na-SWB) are considered among the most promising electrochemical devices for large scale energy storage and the marine sector. In fact, by employing an open-structured cathode, they benefit from the unlimited supply of sodium from seawater. This means that the energy of such systems is intrinsically limited by the capacity of the anode, which, however, can also be stored outside the cell for seasonal/annual energy storage.

Resume : Sodium-air batteries (SABs) are receiving interest as possible alternatives to Li-ion batteries because of their potential to provide high gravimetric energies. The use of suitable cathode materials is a point of major concern as they are responsible for achieving efficient deposition/redissolution of the solid discharge products formed during battery operation. Graphene has gained attention as a cathode material due to its superior electrical conductivity and highly accessible 2D area. Here, we have prepared high-quality graphene aerogels via electrochemical exfoliation using an innocuous biomolecule (adenosine monophosphate nucleotide) and tested them as SAB cathode using a glyme-based electrolyte. The assembled batteries delivered a discharge capacity as high as 9.64 mAh cm-2 and endured 95 cycles at a discharge depth of 0.5 mAh cm-2 with a high current density (0.2 mA cm-2). Such a good performance was attributed to the phosphate groups present in the nucleotide, which is adsorbed on the surface of the graphene sheets comprising the porous aerogel cathode. Therefore, the phosphate groups modify the nucleation mechanism of the discharge products by i) enhancing the interaction of the cathode with oxygen reactive species and ii) catalyzing the ORR/OER reactions during discharge/charge. This latter aspect is of paramount importance for the implementation of rechargeable SABs, as their reversible cycling is the major bottleneck for their commercialization.

Resume : Alkali metal (AM) intercalation compounds based on layered transition metal (TM) oxides and containing Li in the TM layers exhibit capacity in addition to that associated with TM redox by invoking redox reactions on the O2- ions. This O-redox is one of the very few options available to increase the energy density of Li-ion and Na-ion batteries. The nature of the ?oxidized oxide? formed has been widely debated with localized holes (O-), peroxo (O22-), peroxo-like (O2n-) and superoxo (O2-) species being proposed. 1?4 However, we have recently identified molecular O2 as the only species formed upon O2- oxidation in several materials such as Li[Li0.2Ni0.13Mn0.54Co0.13]O2, Na0.75[Li0.25Mn0.75]O2 as well as Li[Li0.33Ir0.33Sn0.33]O2. 5?7 In this presentation, I will show that a similar process takes place for Na0.67Mn0.72Mg0.28O2, containing Mg in the TM layers, and in which the molecular O2 has been identified by high resolution O K-edge RIXS and quantified by SQUID, showing that it equates to the charge passed. The O2 is trapped in clusters of vacancies which are formed by Mg out-of-plane displacement into the AM layer and Mn in-plane disordering within the TM layer, as evidenced by Mg K-edge EXAFS, neutron PDF and DFT. The Mg/Mn honeycomb ordering is therefore lost upon charge and O2 is reduced upon discharge, associated with a large voltage hysteresis. In contrast to compounds containing Li in the TM layer, in which the Li/TM honeycomb ordering and the voltage hysteresis are irreversibly lost after the 1st cycle, in Na0.67Mn0.72Mg0.28O2, this latter is retained upon few cycles due to the partial reversibility of Mn in-plane and Mg out-of-plane migration leading to the local reformation of the honeycomb ordering on discharge, as shown by neutron PDF. 1. Luo, K. et al. Charge-compensation in 3d-transition-metal-oxide intercalation cathodes through the generation of localized electron holes on oxygen. Nat. Chem. 8, 684?691 (2016). 2. Hong, J. et al. Metal?oxygen decoordination stabilizes anion redox in Li-rich oxides. Nat. Mater. 18, 256?265 (2019). 3. McCalla, E. et al. Visualization of O-O peroxo-like dimers in high-capacity layered oxides for Li-ion batteries. Science. 350, 1516?1521 (2015). 4. Chen, Z. et al. Unraveling Oxygen Evolution in Li-Rich Oxides: A Unified Modeling of the Intermediate Peroxo/Superoxo-like Dimers. J. Am. Chem. Soc. 141, 10751?10759 (2019). 5. House, R. A. et al. Superstructure control of first-cycle voltage hysteresis in oxygen-redox cathodes. Nature 577, 502?508 (2020). 6. House, R. A. et al. First cycle voltage hysteresis in Li-rich 3d cathodes associated with molecular O2 trapped in the bulk. Nat. Energy 5, 777?785 (2020). 7. House, R. A. et al. Covalency does not suppress O2 formation in 4d and 5d Li-rich O-redox cathodes. Nat. Commun. 1?7 (2021).

Resume : Current lifestyles have increased energy consumption and as such, there is a need for increasing energy storage capability. Among the available energy storage systems, electrochemical energy storage, and more specifically batteries, are attracting growing attention. However, their autonomy, stability and safety characteristics still need to be improved, and it is anticipated that these features will be accomplished with solid-state batteries. (1) A solid-state battery is an evolution of currently available Li-ion batteries. In these batteries the liquid electrolyte is replaced by a solid electrolyte made of non-volatile and non-flammable components which improves the safety characteristics of the cells. Moreover, the presence of a solid electrolyte enables the use of metallic anodes which enhances energy density. (2) Since Li-based technologies are expected to be mostly used for portable and electric vehicle applications, there is a need to find other options such as Ca, Mg, Zn or Na-based systems for other applications.(3) In this work Na has been chosen as an alternative to Li-based batteries. Na is more abundant than Li, (thousand times higher) and is therefore expected to be less affected by market fluctuations. Although its kinetic and energy densities are slower than Li due to the smaller ionic radius of the Li molecules, Na based technologies could be a good alternative for applications in which the space and weight limitation is not a handicap, i.e. stationary storage systems.(4) This work is focused on the development of an all solid-state sodium battery. More specifically, a layered oxide is selected as the cathode active material, a PEO based polymer as the solid electrolyte and metallic Na as the anode. Electrolyte membranes and high active material-loading cathodes with different sodium salts in their composition were prepared and characterized with the aim of analyzing their suitability in a PEO based sodium solid state battery. 1. Manthiram, A., Yu, X. & Wang, S. Lithium battery chemistries enabled by solid-state electrolytes. Nat. Rev. Mater. 2, 1?16 (2017). 2. Varzi, A., Raccichini, R., Passerini, S. & Scrosati, B. Challenges and prospects of the role of solid electrolytes in the revitalization of lithium metal batteries. J. Mater. Chem. A 4, 17251?17259 (2016). 3. Biemolt, J., Jungbacker, P., van Teijlingen, T., Yan, N. & Rothenberg, G. Beyond lithium-based batteries. Materials 13, 425 (2020). 4. Kundu, D., Talaie, E., Duffort, V. & Nazar, L. F. The emerging chemistry of sodium ion batteries for electrochemical energy storage. Angew. Chemie - Int. Ed. 54, 3432?3448 (2015).

Resume : Sodium ion batteries (SIBs) can be considered a good alternative to Li-ion due to the abundance of sodium sources and the low cost. However, their development also faces challenges such as poor cycling stability and unsatisfying rate performance. Traditional electrodes use binders in such a way as to integrate the active phase within a matrix that gives mechanical stability and assists it during the charging and discharging processes. Unfortunately, binders are generally electrochemically inactive and insulating, which reduces the overall energy density and leads to poor cycling stability. Therefore, binder-free electrodes provide great opportunity for high-performance SIBs. This work is focused on the development of innovative cathode materials based on sodium-manganese-phosphate (NaMnPO4) homogeneously dispersed in carbon nanofibers (CNF) synthesized by electrospinning technique. The latter has allowed the synthesis of materials characterized by nanometric dimensions and the introduction of a carbonaceous matrix, this in order to improve the electrocatalytic activity and the electrical conductivity. The one-dimensional materials thus synthesized have a high specific surface and porosity, thus offering a good connection between active matter and electrolyte with a consequent advantage in terms of insertion and extraction of sodium ions. The technique allowed to obtain a flexible binder-free electrode having by an appropriate specific surface equal 150 m2 g? 1 NaMnPO4-CNF.

Resume : Among the different technologies, Na-ion batteries could play a role in substituting Li-ion batteries where the specific and volumetric energy and power are not the main requisites. Indeed, the cost per Wh of Na ion batteries with organic electrolyte is still comparable to that of Li ion batteries, despite the distributed availability and lower costs of sodium, given their lower specific energy [1]. The way to decrease the cost is to use aqueous electrolytes that also contribute to increase safety [2]. In addition, the adoption of water-based process to produce the electrodes is a suitable strategy toward sustainability [3]. This study focus on the use of natural and sustainable polymers that can be processed in water and, nonetheless, guarantee the stability of the electrodes in aqueous electrolyte. The results of physico-chemical characterization of the materials and the electrochemical test on the Na-ion cell are here reported and discussed. Acknowledgments Ministry of Economic Development, and ENEA PAR 2019-2021 project are gratefully acknowledged for the research funding. References [1] S. F. Schneider, C. Bauer, P. Novák, E. J. Berg, ?A modeling framework to assess specific energy, costs and environmental impacts of Li-ion and Na-ion batteries,? Sustain. Energy Fuels, 2019, 3(11), 3061?3070. [2] D. Pahari, S.Puravankara, ?Greener, Safer, and Sustainable Batteries: An Insight into Aqueous Electrolytes for Sodium-Ion Batteries?, ACS Sustainable Chem. Eng., 2020, 8, 10613-10625. [3] D. Bresser, D. Buchholz, A. Moretti, A. Varzi, S. Passerini, ?Alternative Binders for Sustainable Electrochemical Energy Storage-the Transition to Aqueous Electrode Processing and Bio-Derived Polymers?, Energy and Environmental Science 2018, 11, 3096?3127.

Resume : Li-ion batteries are currently the most dynamically growing devices for electrical energy storage for portable electronics, electric and hybrid vehicles, and large-scale energy storage. Since resources of lithium and transition metals, particularly cobalt, are limited and expensive, cobalt-free Na-ion batteries have been recognized as one of the potential candidates for next-generation rechargeable batteries. They are characterized by a comparable energy density, significantly reduced costs, and practically unlimited resources of sodium. Currently, the major challenge in advancing Na-ion batteries technology is to find suitable cathode materials based on abundant, low-cost, safety and environmentally benign elements such as iron and sulphur. One of the most promising candidates from this group is Na2Fe2(SO4)3 which contains only low-cost and abundant elements. Na2Fe2(SO4)3 exhibits the highest Fe3+/Fe2+ redox potential found so far, equal to 3.7 V vs. Na+/Na. Such a high redox potential combined with a high capacity for sodium intercalation (x in Na2-xFe2(SO4)3 ranges from 0 to 1.7) leads to a particularly large theoretical energy density of 456 Wh kg?1. Until now, only some synthesis methods were used to obtain Na2Fe2(SO4)3 compounds. Moreover, these methods are characterized by a high degree of complexity and require a long synthesis time and a high energy input. Herein, we present a facile, low cost, green chemistry, low-temperature synthesis method yielding nanometric Na2Fe2(SO4)3 cathode material with very promising electrochemical properties. To optimize the 3D microstructure of the layered Na2Fe2(SO4)3 cathode material, X-ray microscopy and nano X-ray computed tomography were used for high-resolution imaging. The system Na/Na+/Na2Fe2(SO4)3 exhibited an energy density of 407 Wh kg?1. The capacity retention of the cell was above 90% and no microstructural changes were observed after 50 cycles, which points to exemptional stability of the electrode.

Resume : Organic batteries have been attracting rapidly increasing interest in recent years owing to the great progress that has been achieved in the synthesis of advanced molecular structures, rendering the realization of truly sustainable high-performance batteries very well possible.[1?4] However, the path towards commercialization is still long and a series of challenges remains to be addressed, including amongst others improvable volumetric and gravimetric energy densities, the difficulties in synthesizing lithiated organic materials that can be reversibly release the lithium cations, the need for large amounts of conductive carbon in the electrodes, and, very generally, an in-depth understanding of the processes and reactions occurring.[1?4] In fact, one aspect that is frequently overlooked is that also organic active materials come as ?particles? rather than single molecules. Herein, a comprehensive analysis of tetra-lithium perylene-3,4,9,10-tetracarboxylate (PTCLi4) as an exemplary organic active material is provided, starting from an in-depth investigation of the de-/lithiation mechanism by merging theory and experiment towards an optimization of the electrode composition with the target to realize commercially relevant performance metrics. References [1] P. Poizot, F. Dolhem, J. Gaubicher, Current Opinion in Electrochemistry 2018, 9, 70. [2] B. Esser, F. Dolhem, M. Becuwe, P. Poizot, A. Vlad, D. Brandell, Journal of Power Sources 2021, 482, 228814. [3] P. Poizot, F. Dolhem, Energy Environ. Sci. 2011, 4, 2003. [4] Y. Lu, J. Chen, Nature Reviews Chemistry 2020, DOI 10.1038/s41570-020-0160-9.

Resume : Due to the increasing demand of battery technology for applications in mobile and stationary devices, this is a fast-growing economic sector. Within the last decades, lithium ion batteries have been subjected to a continuous process of development and further improvement ? not only in terms of power and energy density, but also with focus on safety and sustainability. To overcome drawbacks concerning solvent-based manufacturing routes, new water-based routes are evaluated, using a variety of water-processable and therefore more sustainable materials. One promising alternative for fluoride-based binder polymers in battery electrodes is sodium alginate, which is a seaweed harvesting product. We have examined sodium alginate not only as bio-based binder for different applications in lithium and sodium ion battery electrodes, but also as an additive for the preparation of separators and as electrolyte in fuel cells. Sodium alginate offers a great bandwidth of possible engineering applications with high potential to improve existing systems both in terms of sustainability and biodegradability without cutting its performance. To conclude, bio-based sodium alginate is a suitable alternative for a big variety of applications in the battery sector. It is a polymer offering low environmental impact, good biocompatibility, and no negative influence on human health. Additionally, sodium alginate comes up with comparable results in terms of mechanic and electrochemical performance.

Resume : Electrical energy storage (EES) devices have staged important technological revolutions in the past years, with special attention given to Li-ion batteries (LIBs). However, novel socioeconomical paradigms[1] have urged for environmentally friendly and sustainable alternatives regarding these technologies. In this context, organic materials have attracted attention as potential candidates to pave the way toward the achievement of truly green batteries. They offer several advantages like cost efficiency, sustainability, synthesis from renewable or feedstock and tunable properties.[2] Nonetheless, hindrances related to cyclability and energy density need to be solved before the achievement of such alternative technologies. In this study, we present one possible way to accelerate the discovery of novel organic electrodes, with special focus given to LIBs positive electrodes. To explore the almost limitless organic universe, however, novel methodologies were needed. Based on a combination of density functional theory (DFT) and machine learning approaches we have developed an Artificial Intelligence (AI) algorithm capable of predicting the battery open circuit voltage (OCV) (V vs. Li/Li ). To fuel the AI, two different databases have been developed: a small set of predicted molecular crystals following an interplay between DFT and an evolutionary algorithm[3,4]; a larger set of more than 26000 unique molecules with redox properties extracted from DFT. The rendered AI-kernel relies solely on a textual representation of molecules to obtain the OCV, which allows a fast and efficient assessment of larger materials libraries. Thereafter, a high-throughput screening was performed in 20 million molecules following a capacity (mAh/g) ? OCV (V vs Li/Li ) selection to find suitable electrode candidates, resulting in about 1540 cathodes. As the final part of this screening, new DFT calculations were performed for the selected molecules with a two-fold goal: to validate the AI-kernel performance and to further filter the candidates list. This process led to the discovery of about 500 promising molecules for cathode compounds, with some exhibiting theoretical energy densities superior to 2000 Wh/kg. Moreover, the AI-kernel accurately identified common molecular characteristics that lead to such higher-voltage electrodes and pointed out an interesting donor-accepter-like effect that may drive the future design of cathode-active materials. References: [1] P. T. Brown and K. Caldeira, Nature, 2017, 552, 45?50. [2] S. E. Burkhardt, J. Bois, J. M. Tarascon, R. G. Hennig and H. D. Abruña, Chemistry of Materials, 2013, 25, 132?141. [3] R. P. Carvalho, C. F. N. Marchiori, D. Brandell and C. M. Araujo, ChemSusChem, 2020, 13, 2402?2409. [4] R. P. Carvalho, C. F. N. Marchiori, V.-A. Oltean, S. Renault, T. Willhammar, C. Pay Gómez, C. M. Araujo and D. Brandell, Materials Advances, 2021, 2, 1024?1034.

Resume : The development of sustainable batteries is becoming more and more important to accomplish clean energy goals. However, most of the current batteries, still based on inorganic electrodes that contain scarce and/or toxic elements, so hardly meet these sustainable requirements. In contrast, organic electrodes based on abundant elements are promising alternatives. Among them, conjugated microporous polymers (CMPs) have gained increasing attention due to their extended ?-conjugation and permanent microporosity. Recently, our group reported the advantages of anthraquinone-based CMPs (named IEP-11) as high performing cathode for Li-ion batteries [1]. Being aware of the safety issues associated to Li-ion batteries and of the scarcity of Li resources, we went a step forward by applying our polymer electrodes in safer and more sustainable aqueous batteries. Here, we compare our porous IEP-11 polymer with the state-of the art linear polymer (PAQS) in a polymer || Ni(OH)2 battery configuration using alkaline electrolyte (1M and 10 M KOH). IEP-11 polymer exhibited much better performance over cycling due to its robust 3D porous structure which avoids the typical dissolution problem faced by linear polymers in low concentrated electrolytes. Due to the low cyclability of Ni(OH)2 in concentrated electrolytes, we substituted Ni(OH)2 by a novel NiCoMnSx cathode and the resultant battery outperformed most of the state-of-the-art alkaline batteries in terms of energy and power density [2]. References: (1a) Adv. Funct. Mater. 2020, 30 (6), 1908074, (1b) ACS Energy Lett. 2020, 2945?2953, (2) Manuscript in preparation.

Resume : Batteries have become an essential power source in many areas, due to their capability to deliver high energy densities in a portable manner. Furthermore, its demand is forecast to increase exponentially with the blooming of devices for the Internet-of-Things (IoT). Although secondary batteries seem to be the more suitable solution, many applications in which logistics requirements make battery recovery very unlikely, rely on the primary non-reusable option. In many of those cases, batteries must be adapted to the system size and form factors, making the recycling process even more challenging, thus aggravating the environmental impact associated with the generation of waste electrical and electronic equipment (WEEE). Furthermore, a close look at their life cycle reveals that they follow an obsolete linear model of production, consumption and disposal, which relies on scarce non-renewable resources and materials, contributing significantly to the ecosystem degradation. The current situation sets a great opportunity for re-thinking the battery paradigm by placing sustainability at the heart of the process. This talk will introduce a primary battery concept that turns around the typical battery life cycle. Eco-design principles have been applied since the device conception to explore new material applications, employ low energy consuming fabrication methods and customize energy supply while reducing environmental stress. The identification, optimization and application of new materials represented a pivotal step in this work. Abundant plastic-free, non-toxic materials are selected for all battery parts, from the substrate to the active redox species. Carbon-based current collectors are generated via Laser-Induced Graphene (LIG) over a pre-treated cardboard surface. Bio-polymer matrices synthesized from naturally occurring polymers, such as cellulose or alginate, are used to create hydrogels that retain the electrochemically active species and as ion exchange membrane. Their unique composition would allow batteries to follow alternative end-of-life scenarios, such as being recycled with paper/cardboard or being composted. This battery concept represents a feasible pathway to develop truly sustainable portable energy storage devices for application sectors such as smart packaging and precision agriculture.

Resume : In recent years, interest in the development of organic electrodes for batteries with materials extracted from biomass rather than using synthetic routes has intensified, with the aim of making energy storage more environmentally friendly. To accelerate and simplify the search for promising compounds as potential electroactive materials in these sustainable batteries, computational procedures may be employed to complement the experimental approaches in view of guiding the selection of most promising backbones and functionalizing groups or to understand in detail the electrochemical mechanisms. The success of researches in this area relies on the discovery of performant compounds or materials, which can be assisted from both predictive power with atomic and mesoscale resolution and accurate scrutinization of structure property-relationships. With the aim of delivering unique insight and understanding of this class of materials, Density Functional Theory (DFT) [1] and Coarse-Grained Molecular Dynamics (CGMD) [2,3] can be partnered with experimental synthesis and characterization tools. In such a global approach, the panel of properties accessible encompass structure, slurry viscosity, evaporation, electrode calendering, diffusion and electrochemical features. Through molecular DFT calculations, the systematic exploration of modified or completely new compounds can be conducted either through screening of the effect of functionalization, isomerization or substitution inside a family or across several series of backbones or even through redox centers modulation. This tool can confirm or infirm chemical intuitions at a first glance, therefore helping to identify or even to engineer most suited candidates thanks to design and optimization considerations. Besides, based on the accurate electronic structure examination, structure?activity relationships can be established to unveil the origin of the redox potential magnitude as a function of both structural features and complexation effects. On the other hand, periodical DFT and CGMD calculations may assist in particular the comprehension of intercalation features and electrode manufacturing in the context of real-life experiments, respectively. A glimpse of the challenges and complementary approaches encountered in this research area will be presented through the consideration of a few case studies. [1] F. Lambert, Y. Danten, C. Gatti, C. Frayret, Phys. Chem. Chem. Phys., 2020, 22, 20212-20226. [2] A. A. Franco, A. Rucci, D. Brandell, C. Frayret, M. Gaberscek, P. Jankowski, P. Johansson, Chem. Rev. 2019, 119, 4569?4627. [3] M. Chouchane, A. Rucci, T. Lombardo, A. C. Ngandjong, A. A. Franco, Journal of Power Sources, 2019, 444, 227285.

Resume : The solid-state battery has drawn a huge interest with its motive to overcome the issues and challenges faced by batteries using conventional liquid electrolytes. The novel idea of using green approaches or bio-based sources for lithium batteries excites many researchers due to their eco-friendly, less carbon footprint in its synthesis and recycling at the end. In this work, we report a full bio-based solid-state electrolyte based on functionalized carbonated soybean oil (CSBO) obtained from the naturally occurring epoxidised soybean oil (ESBO) using CO2 and biomass. CSBO shows remarkable adhesive properties as characterized by rheological measurements owing to its bigger chains bearing multifunctional cyclic carbonates. LiTFSI salt reinforced CSBO was characterized following standard electrochemical measurements exhibiting ionic conductivity to ~10-3 S cm-1 at 100 oC and 10-5 S cm?1 at room temperature. The electrochemical window for this electrolyte was obtained to be 4.8 V (vs. Li/Li ) and transference number up to 0.31, allowing it to be explored for high voltage cathodes. CBSO shows stable stripping and plating behaviour for longer cycles making it a good candidate for higher coloumbic efficiency electrolyte batteries. We also demonstrated the galvanostatic charge-discharge of LiFePO4 (Lithium Ferrrophosphate, LFP) with CSBO electrolytes delivering the gravimetric capacity of 124 mAhg-1 and 150 mAhg-1 appx. at ambient room and higher temperature respectively. Therefore, our study provides a promising direction of developing bio-based solid electrolytes to facilitate progress in sustainability, cost-effective and safe manner to create a solid-state lithium-ion battery for global utilization.

Resume : The apparent ease to prepare films by pulsed laser deposition (PLD) with a complex stoichiometry hides the underlying complex and simultaneously occurring phenomena in the laser-induced plasma. Often the film growth suffers from the competition between light and heavy elements in the expanding plume with heavy species possessing a high kinetic energy as compare to lighter species. As a result, there are significant differences in the arrival time to the substrate causing compositional spatial deviation in both the plasma plume and the film. For a targeted growth of films with a complex composition, it would be therefore highly desirable to have a more detailed understanding of the scattering process and plasma chemistry that take place inside the laser-induced plume. The deposition of Li containing materials to prepare Li-ion battery thin films has been widely performed by PLD. Due to the small mass of lithium, Li-containing materials often undergo this competition with heavy elements detrimental to film growth and composition, respectively. The main goal of this research is to perform detailed elemental, spatially and time resolved optical and mass spectroscopic measurements of PLD processes of Li-containing materials such as LiMn2O4. Investigating the mechanisms involved such as the plasma plume formation, expansion, and subsequent film growth will benefit lithiated material manufacturing. Establishing more predictable deposition boundary conditions with respect to film growth will help to improve battery material performances.

Resume : Li ion transport mechanisms in the bulk of electrolytes, for applications in Li ion batteries, however complex they might be, are well documented and dictated by the interactions between the solvent and each ionic species. However, when two different phases meet, namely the electrode material and the electrolyte, a plethora of different phenomena come into play. These phenomena set the limitations on the engineering for safety and efficiency of a Li ion battery. The trend towards solid state electrolytes is considered the most effective safety-wise but the solid to solid contact between the electrode and the electrolyte places a tremendous barrier in the smoothness and uniformity of Li diffusion through the interface. Low molecular weight poly(ethylene oxide) (PEO) based electrolytes offer remarkable conductivity of ~10-4 S/cm at room temperature but present no mechanical stability. On the other hand, solid polymer electrolytes (SPEs) present the necessary elastic properties but the contact with the electrodes is problematic, since they cannot comply to the roughness or porosity of the electrodes and the contact area is considerably reduced. Many ways to conformally comply the surface of the electrodes with that of the SPE have been studied, such as in situ polymerization, use of self-assembled block copolymer PEO molecular layers and high molecular weight PEO casting. A liquid or viscus electrolyte could mediate the interface between SPEs and electrodes optimizing the contact area. Especially in the case of lithium metal electrodes, when the electrolyte comes into contact with lithium, chemical or electrochemical reactions lead to the formation of an interphase (solid electrolyte interphase ? SEI) that passivates the electrode and protects the electrolyte from further consumption. This work is focused on the investigation of the behavior of PEO based liquid or viscus electrolytes in contact with lithium metal anodes. In this study we try to understand the formation of the composite layer and the evolution of SEI over time as well as the resultant change in conductivity. For this purpose, different electrolytes placed into contact with lithium electrodes and their behavior was monitored through impedance spectroscopy. All the systems studied, were prepared by solvation of bis(trifluoromethane) sulfonimide lithium, LiN(SO2CF3)2 (LiTFSI). The polymers used as solvents for the salt were the following: hydroxy poly(ethylene glycol) with molecular weight 550 g/mol (PEG550), dimethyl poly(ethylene glycol) with Mw 250 g/mol (PEG250-dME), a blend of 30% w/w poly(methyl methacrylate) PMMA (Mw 100 kg/mol) with 70% w/w PEG550 (PMMA/PEG550) and a blend of 30% w/w PMMA with 70% w/w dimethyl poly(ethylene glycol) with Mw 1000 g/mol (PMMA/PEG1k-dME). Al the electrolytes have been mixed with the salt in the same ratio of r = [Li ]:[EO] = 0.055 ([EO]:[Li ] = 18.2:1). For comparison a carbonate electrolyte of ethylene carbonate and diethyl carbonate LiTFSI 1M (EC/DEC) has also been studied. All the electrolytes were enclosed in symmetric cells with lithium electrodes, with the assembly performed in argon-filled glove box with levels of O2 under 100 ppm and ?2? under 1 ppm. The systems of low molecular weight, PEG electrolytes are in liquid state while the blends with PMMA are viscus at room temperature. By comparison of PEG550 and PEG250-dME it is seen that the formation of the SEI is a fast process which is completed during the first hours, from the first contact with the lithium metal electrodes. A second phase is observed that it is attributed to the formation of inorganic lithium salt compounds that evolve in a slower rate of days. The PEG550 shows a significant electrolyte decomposition, due to the formation of a weak SEI while at the same time a thick inorganic phase hiders Li ion transport. In contrast the PEG250-dME electrolytic system shows a stability sourcing from the formation of a SEI that is mechanically stable and a thinner inorganic layer. The comparison of the viscus electrolytes of blended PMMA and PEG follow a similar behavior. The PMMA/PEG550 electrolyte shows the characteristic reaction of PEG550 with the lithium metal leading to a SEI formation. The SEI dynamic behavior resembles that of PEG550 with the characteristic frequencies being very close for the two systems, indicating a similar SEI environment. The PMMA/PEG1k-dME shows a different dynamic behavior in comparison to the PEG250-dME system, with the characteristic frequency being more than an order of magnitude lower, probably due to the higher molecular weight of the PEG. It is interesting to note that by comparing the resistances of the SEI between the two blends there appears a remarkable similarity in their time evolution, which probably indicates that PMMA also contributes to the formation of the SEI. The low viscosity of low molecular weight PEG electrolytes allows for an effective electrode wetting and conformal matching of solid polymer electrolyte to electrode surfaces, while at the same time methoxy chain termination limits the molecule reactivity with lithium and promotes the formation of a stable SEI. The prospect of this work is to bridge electrode and SPE materials mechanically as well as electrically using low viscosity electrolytes. In order to determine the behavior of various PEO based electrolytes and their ability to passivate the anode materials, improve the solid to solid contact, achieve better diffusion for Li and extend cyclability of the lithium ion cells.

Resume : Within the BMBF-funded international collaborative project INNENERMAT, the partners are developing flexible batteries and supercapacitors and proof-of-concept for the hybridization of mentioned systems in a multidisciplinary approach. Safe and environmentally friendly high-performance cathodes and anodes, gel and polymer electrolytes and smart carbon textile electrodes for flexible energy storage cells are realized through the development of advanced functional materials. Here the primary results on the development of lithium sulfur battery component within INNENERMAT project are presented. Carbon xerogels with different size of feeder pores were developed and tailored with defined amount of microporosity to immobilize sulfur species within the cathode [1]. Preparation and associated effect on the electrochemical performance of such electrodes is investigated. To this end, the influence of preparation method such as grinding, handling, stability and viscosity on the wet coating process as well as on the quality of cathode sheet in terms of defects and flexibility is discussed elaborately. Furthermore, the infiltration of sulfur into the carbon matrix is particularly studied for this innovative class of carbon materials [2]. In order to immobilize the polysulfide anions, the strategy adopted in this work is that of employing innovative single ion conductor-solid polymer electrolytes (SLIC-SPEs), providing suppressed anion mobility. For this purpose, lithiated Nafion-based nanocomposite membranes were synthesized via dispersion of nano-additives bearing suitable functional groups [3]. Two nanostructures have been investigated: graphene oxide (GO) and Nanoscale Ionic Materials (NIM) functionalized membrane. The presence of nanoparticles in the polymeric matrix is of great interest not only due to the significant gains in thermal and mechanical stability, but also the consequential barrier effect, hindering the diffusion of polysulfides and enhancing the cyclability of the cell. The implementation of these kinds of membranes have already been successfully demonstrated for lithium ion battery cathode and in the presented work the incorporation in the lithium sulfur system is showcased.

Resume : Na-ion batteries (NIBs) could be a good alternative to Li-ion batteries (LIBs) due to the large abundance and availability of sodium resources. The search for good anode materials is one of the big challenges since graphite, which is the most common anode material for LIB, does not work well in NIBs. We are developing Bi2MoO6 as an anode material for NIBs, and will explain the main cycling mechanism. By utilizing a combination of conversion and alloying reactions, the material achieves high capacity while still maintaining a decent cycling stability. The complex cycling mechanism also makes it an interesting and challenging material to characterize during cycling. In this poster, we present high quality operando XRD data of the material during several cycles, acquired in the home lab. The data clearly shows that the reversible alloying reaction of Bi-metal to cubic Na3Bi gives the main capacity contribution, after the initial conversion reaction. This indicates formation of nanocrystalline Bi-particles, as nanocrystalline Bi-metal has shown the same reaction mechanism while microcrystalline Bi instead forms the hexagonal phase of Na3Bi. The molybdenum goes into an amorphous matrix that is only partially electrochemically active. The phases formed with molybdenum during cycling are difficult to characterize, due to their amorphous nature, and remain an unsolved mystery.

Resume : Lithium-ion batteries (LIBs) are one of the most promising technologies for electric energy storage. They have some advantages over conventional rechargeable systems, such as a high output voltage and low self-discharge. Being the bottleneck of its performance, the cathode of LIBs are of great interest of study, more specifically in reducing the cobalt content, a mineral expensive and toxic. Here, we use the CALPHAD (CALculation of PHAse Diagram) approach to obtain a thermodynamic description of typical cathode based on NMC materials (layered host compounds with nickel, manganese and cobalt). Combining crystallography, phase diagrams and thermodynamic information, we develop a model with Gibbs energy functions for every phase that can appear in the cathode during battery operation. This model allows us to calculate important properties such as cell voltage, release of oxygen and phase stability. At a first moment, we focus in the Li-Ni-O system, typical of LIBs that use LiNiO2 as host compound. Even though this compound provides a very high theoretical energy density and has no cobalt, there are issues regarding its synthesis and it usually presents a considerable loss of its capacity after the first charge due to irreversible changes in its crystalline structure. We propose an ionic model, where we can provide information on the oxidation degree of nickel atoms during battery operation. We also assess the system in temperatures higher than room temperature, where we accomplish a better comprehension on how the synthesis conditions affect the host compound. Finally, as a future work, we extend the model to systems representative of NMC cathodes. The NMCs with equal amounts of each transition metal are very stable as lithium deintercalates over battery charging. However, the automobile industry demands LIBs with increasingly higher capacity, which is possible by adding more nickel in the host structure and losing some structure stability as counterpart. We use the model to sweep over a wide range of NMC compositions in order to find optimal ones in terms of performance, safety and stability.

Resume : Among the electrochemical storage technologies, sodium-metal-chloride batteries are currently of great interest from research. In this regard, one of the predominant activity concerns the reduction of the operating temperature, which is mainly affected by the limited ionic conductivity of the solid electrolytes typically used in these batteries (0.2 S/cm @ T > 250 °C). In this work, various electrolytic materials with different chemistry, have been successfully synthesized by solid-state reaction and tested as sodium-ion conducting electrolytes. In particular, all the samples are Nasicon-based powders prepared with excess of sodium Na3.3Zr2Si2PO12, or substituted with different metals characterized by ionic radius similar to that of zirconium Na3.3M0.5Zr1.5Si2PO12 (i.e. Mg, Cu, Zn, Co, Fe). Nasicon pellets were prepared from these powders by uniaxial pressing, then sintered at suitable temperature. The activity was aimed at understanding the impact of the composition of the electrolyte on sodium ion conductivity through in situ measurements, using diagnostic techniques such as electrochemical impedance spectroscopy (EIS). Moreover, structural, chemical and morphological characterizations were carried out on the prepared materials using various experimental techniques including X-ray diffraction (XRD), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), spectroscopy photoelectronics (XPS).

Resume : Laser pyrolysis in a flow reactor designated for silicon nanoparticles has been used to synthesize composite nanostructure having distinct Si and Sn nanocrystals, aiming to obtain a nanomaterial with potential high performances for Li intercalation in anodes for the corresponding rechargeable batteries. Particularly, silane gas act in these configuration with a double role: Si precursor and reaction sensitizer (laser energy absorber). In this study we intended to analyse the structural and morphological changes of resulted composite nanostructure by progressively increasing the Sn precursors (Sn(CH3)4 vapors) flow, up to 22 sccm in the reactive mixture containing a constant SiH4 flow, 20 sccm. Thus, to generate nanoparticles having a low degree of agglomeration, the laser beam was focused at 1.3 mm together with the reactive mixture dilution with Ar and its flow was adjusted in order to keep the same total mixture flow (120 sccm). The as synthesized powders show distinct Si and metallic Sn beta phase nano-crystallites after XRD analysis. Also, the crystalline domain of Sn phase tend to increase with Sn(CH3)4 flow increasing. TEM investigations revealed distinct nanocrystals in the same NPs agglomeration: The mean Si crystal size are the lower (10 nm mean size) and Sn are the bigger one (up to 30 nm). The elemental composition was evaluated with EDX and the specific surface area by BET analysis. These NPs and their RGO composite will be evaluated for their electrochemical performances, including charge/discharge cyclability for performant Li ion anodes.

Resume : We report the synthesis of two different batches of Si nanoparticles (NPs) using laser pyrolysis of silane, their crystallite and nanoparticle size decreasing with the increasing of precursor gas speed by narrowing the cylindrical injector diameter. Thus, the bigger NPs (named SiA1) have mean XRD diameter around 30.7 nm, whereas for the smaller ones (SiA4) the mean value is 21.7 nm, values confirmed also by SEM analyses. For the composite synthesis, the Si NPs were ultrasonicated in the presence of water-dispersed graphene oxide (obtained by graphite oxidation with KMnO4/H2SO4 using a modified Hummer recipe), continuated by the mixture reduction in lyophilized dry state under H2 flow in a furnace or in liquid suspension with ascorbic acid followed by washing and lyophilisation. The resulted Si NPs and their powdered nanocomposites with RGO were used for the Li-ion anodes fabrication by adding conductive carbon black support (only for those based on raw Si NPs) and binders: poly(vinylidene fluoride) (PVDF) in N-methyl pyrrolidone (NMP) or carboxymetylcellulose (CMC)/styrene-butadiene rubber (SBR) in water and deposed by spraying or roll-to-roll techniques, respectively. They were subsequently tested in CR 2032 half-cells (having a Li foil as cathode) two electrode configuration (and also half-cell with three electrodes configuration - PatCell testing system) using LiPF6 salt dissolved in organic carbonates mixture (EC : EMC : DEC 3wt.% FEC). Depending of employed recipe and deposition technique their performances after 200 cycles at 1C were greatly different, for example for an electrode containing 15 wt% SiA1 NPs deposed by roll-to-roll: 734 mAh/g, whereas for an electrode with 15 wt% SiA4 NPs and deposed by spraying presented a 475 mAh/g capacity (also at 1C) after the same number of cycles in the conditions of their relatively high C black content (68 wt% for those withSiA1 and 80 wt% fo those with SiA4) . Also, the electrodes fabricated with Si NPs-RGO nanocomposites are under testing for cyclability performances. Preliminary electrochemical impedance analyses showed internal resistances between 4 ? 36? , whereas the cyclic voltammetry tests which were performed at 0.001 ? 3V, at 0.1 mV·s-1 scanning rate presented the expected the oxidation/reduction peaks in the region up to 0.75 V.

Resume : Renewable energy sources, such as solar radiation, are alternatives to supplant fossil fuels. However, because of the variability in time as well as geographic distribution, devices to store the generated energy are needed. Supercapacitors can store the energy generated by other energy sources and deliver it when necessary. There are two types of supercapacitors: electrostatic double layer (EDLC) and pseudocapacitors (PSC). PSC store energy by faradaic reversible redox processes (oxidation-reduction) that occur within the electrode material, being this phenomenon known as pseudocapacitance. Until now metal oxides, metal hydroxides and organic polymers have been used in PSC. Organic polymers present high specific energy and power, high conductivities and are flexible. However, most of these organic polymers are synthetized by complex chemical methods involving several steps which are expensive and also generate waste. A strategy that can be used in the deposition of organic polymers is the electropolymerization. Electropolymerization is a very versatile procedure to construct organic films over metallic contacts, or over transparent conducting oxides. By electing the correct polymerization group and the correct desired functionality, a significative number of monomers can be designed and synthetized to generate polymers. In this work we present the electrochemical formation and characterization of porphyrin films obtained by electrochemical polymerization. The used porphyrin monomers have two carbazole and two triphenylamine electroactive groups, which were chosen to undergo electrochemical initiated radical coupling that promotes the formation of polymeric structures. Also, two central hydrogen atoms were substituted with different central metals (Zn (II), Co (II), Cu (II)). The monomers and the electrogenerated films were characterized by cyclic voltammetry, UV-vis spectroscopy, AFM, SEM and Electrochemical Impedance Spectroscopy (EIS). Because of the reversible oxidation-reduction processes involving the porphyrin macrocycle, the dicarbazole and the tetraphenylbenzidine groups present in the polymeric structure, it was expected a pseudocapacitive behavior that would make the porphyrin films adequate for their use as active material in the construction of supecapacitors. The porphyrin films were characterized by charge-discharge cycles at different current densities. The discharge and charge curves were nearly mirror images, indicating a fast and reversible electron exchange. The pseudocapacitive electrode materials exhibited capacitances as high as 201 F/g at a current density of 2 A/g. These high capacitances demonstrate that the porphyrin films are promising materials for energy storage applications where a high discharge-recharge rate is needed.

Resume : Metal halide perovskites have been recently proposed as promising anode materials for energy storage applications.1,2 Despite their quite important electrochemical characteristics, all the perovskite-based anodes are synthesized at high temperatures (90?150 °C) and with reaction durations of the order of tens of hours. In this work, we present perovskite materials synthesized with room temperature, simple and fast approaches for high-performance and stable electrodes for Li-air batteries. Hexagonally-shaped nanocrystals capped with ligands3 and ligand- free microcubes4 synthesized with re-precipitation based protocols will be compared according to their storage capacity and stability. Specifically, it is shown that the electrodes incorporating the ligand-free microcubes present outstanding stability at the same time with high specific capacity compared to the ligand-capped nanoparticulate system. These could be attributed to the high crystal quality of the materials and thus enhanced electrical conductivity, even under operation with an aqueous electrolyte. The large interfacial area between the perovskite material and the electrolyte along with the increase of the active sites on the exposed microcubes facets favor the Li ion intercalation. In addition, the absence of capping ligands contributes further to the enlargement of contact area, and facilitates the ion penetration compared to ligand capped nanocrystals. The good crystallinity of the microcubes enhances the Li-ion intercalation and the electron transportation. The microcubes performance is the best among all the anodes utilizing metal halide perovskite nanostructures, reported to date. References 1) Kostopoulou et al., Journal of Materials Chemistry A 2018, 6, 9765. 2) Kostopoulou A., Nanophotonics 2019, 8, 1607. 3) Kostopoulou A., Nanoscale 2019, 11, 882. 4) Kostopoulou A., Journal of Power Sources Advances 2020, 3, 100015. Acknowledgments: ?.?. would like to acknowledge the Hellenic Foundation for Research and Innovation (HFRI) and the General Secretariat for Research and Technology (GSRT) (under grant agreement No 1179) and K.B. EU H2020 Research and Innovation Program under Grant Agreement N820677 and Greek State Scholarships Foundation (IKY) through the operational Program «Human Resources Development, Education and Lifelong Learning» in the context of the project ?Reinforcement of Postdoctoral Researchers - 2nd Cycle? (MIS-5033021), for the funding.

Resume : In recent years a growing demand for environmentally friendly transportation led well known car producers to introduce electric powered vehicles (EV) to their fleet. This development caused a growing demand for lithium-ion batteries (LIB) with high energy density and long cycle life, leading to the development of high voltage and high capacity electrode materials. However, their performance is still limited by fast decomposition of electrolyte components at high currents or beyond a defined voltage threshold, beyond 4.5V. There is a large number of researchers devoting their work to improve lifetime and safety of lithium ion battery (LIB) cells. One way to achieve these goals unfolds by adding functional organic compounds as additives to carbonate-based electrolytes. Vinylene carbonate (VC) and fluoroethylene carbonate (FEC) for SEI formation are common additives which are commercially used in state-of-the-art electrolytes. However, a new chemical class of additives has shown to address other aspects of cell degradation. Electrolyte decomposition stemming from harmful substances can be interrupted with scavenging additives. The conducting salt lithium hexafluorophosphate (LiPF6) for instance decomposes and reacts with water to yield hydrofluoric acid which further leads to the degradation of the SEI or causes damage to the cathode material. This reaction path can be interrupted at different stages by scavenging water, hydrofluoric acid or an intermediate species by adding additives, that prevent parasitic components from reacting and lead to an improvement of the state-of-health (SOH) in batteries. In this work, Tris-(Trimethylsilyl) phosphite (TMSP) was used as additive for the scavenging of hydrofluoric acid and together with a newly developed operando GC-MS method, the decomposition reactions during battery cycling were investigated. This was used to analyze the gas species evolving from NMC532/Li EL-Cells with and without TMSP during overcharge- and fast-charging-experiments. Gaseous decomposition products play a key role in understanding degradation reactions, therefore, the knowledge gained from these experiments assist in uncovering the mechanistic background of the additive impact and has a supporting role in finding new additives for LIBs. The author gratefully acknowledges the FFG (Austrian Research Promotion Agency) for funding this research within project No. 879613.

Resume : Since lithium-ion batteries have become the mainstream energy storage devices, they have been used in various fields from mobile devices to electric vehicles, ESSs, and smart grids. As energy storage devices are used rather than generators even in larger and harsh environments, the demand for new energy storage devices with superior performance and stability has increased. The ideal structure proposed to satisfy this requirement would be a form in which lithium metal is used for the anode, sulfur is used for the cathode, and a solid electrolyte is positioned between both electrodes. The sulfur electrode has a theoretical capacity of at least five times greater than that of the conventional cathode, and it is expected to improve the performance of the energy storage device. However, the sulfur electrode showed disappointing results in existing experiments. When the sulfur electrode is combined with lithium, it spreads to all parts of the cell through a shuttle effect, which is not easily controllable and reversible. Early studies tried to prevent the shuttle effect by enclosing the sulfur electrode in a certain structure, but the sulfur dissolved in the liquid electrolyte, passed through the structure, and spread all over the cell, also the corrosive nature of sulfur accelerated that operation. When lithium was removed from sulfur, poor conductive sulfur was irregularly precipitated inside the cell, which seriously obstructs repeated charging and discharging and stable operation. Thus, later studies attempted to improve the structural reversibility and conductivity of the sulfur electrode by composing most of the electrode with sulfur and then mixing little additives, rather than trying to confine sulfur in the structure. In this study, the performance of the sulfur electrode was greatly improved by using the nano additive. The nano additive was a material with a highly controlled internal structure and high surface areas, such as graphene pomegranate pockets and nitrogen-rich carbon nanotubes. For example, the graphene pomegranate pocket provides conductivity to the sulfur electrode and has low interfacial energy with the electrolyte-sulfur solution, which makes the sulfur solution stable around. In addition, when removing lithium from the sulfur electrode, a stable reaction was induced by allowing the sulfur to be precipitated around the graphene pomegranate pocket. In addition, in the case of nitrogen-rich carbon nanotubes, a structure extending in one direction was uniformly stacked to provide excellent conductivity, and a sulfur solution was accommodated in a large internal space. In addition, the low interfacial energy with the sulfur solution allowed the solution to stay in the vicinity of the nitrogen-sufficient nanotubes, and a structurally reversible reaction was induced during charging and discharging. We verified stability through over 3000 charge/discharge reactions and achieved over 95% coulombic efficiency and theoretical capacity.

Resume : On the main trends that drive energy storage development in our daily life is the rise of electrical devices, Internet of Things and battery-powered medical devices and implants. Despite its great success and mature custom manufacturing market, lithium ion batteries (LIBs) still need improvements in energy power density, speed charge capabilities, cost, and cyclic durability. In this context, in recent years, extensive efforts have been devoted to either improve lithium ion batteries (LIBs) by replacing commercial cathodes and anodes, improve electrolyte properties or designing new batteries without Lithium (Li) (e.g. Al, Mg, Na and Zn batteries) responding to the concern raised by the limited Li resources. Among new materials investigated in the literature, graphene and vanadium oxides (e.g. V2O5, VO2) are outstanding materials due to their unique physico-chemistry properties and their promises in both fundamental research and industrial field. Moreover, vanadium and carbon are sustainable elements sparsely distributed in the Earth?s crust, therefore abundant. There are several advantages to synthesize those materials, such as the unique open-layered structure of vanadium oxides (VOx), which could allow the easy insertion of various cations (e.g. Li and beyond Li ) and the synergetic effect of graphene due to its unique properties (e.g. good electrical conductivity, high surface area) for enhancing electrochemical properties of various materials. Electrochemical electrodes are generally prepared by a conventional coating method following by a drying process for several hours. By introducing physical vapor deposition (PVD) coating of the conductive current collector, we shall be suppressing this time-consuming step. As PVD deposition method, magnetron sputtering (MS) and pulsed laser deposition (PLD) has great potential for construction of electrode materials. Advantages include high adherence of films (which could guarantee long-term durability of electrochemical electrode); purity; easy engineering of the film properties by tuning the deposition parameters; control to atomic level the film thickness in contrast to spin-coating or dip-coating; good reproducibility of source material stoichiometry; MS has been proven to be a scalable technique at industrial level. Meanwhile, PLD technique has been proof an efficient technique for the construction of micro-batteries. Although various approaches have been used to synthesize vanadium oxides and graphene, the use of physical vapor deposition (PVD) as alternative method for energy storage devices is still quite unexplored. In this work, we report the synthesis of undoped and doped vanadium oxide polymorphs (e.g. V2O5, VO2(B)) and graphene by magnetron sputtering and pulsed laser deposition. Various substrates, such as Silicon, Aluminium, Nickel foil and Nickel foam were employed to deposit the thin films. The physico-chemical properties of the thin films were multi-parametrically surveyed by SEM, EDXS, Raman, GIXRD and spectroscopic ellipsometry. The electrochemical properties have been evaluated by cyclic voltammetry, and impedance spectroscopy and galvanostatic discharge?charge cycling in various electrolytes. Compared with the bare vanadium oxides, VOx/graphene electrodes exhibited enhanced electrochemical properties. Furthermore, we show the tailoring of the electrodes properties with defect (e.g. doping) engineering represent an excellent strategy to boost even further their performances. This work provides alternative approach to prepare electrode materials based on vanadium oxides and graphene for application in electrochemical energy storage.