Locating novel polyanionic cathode materials for Li-ion batteries in underexplored chemical spaces Bonan Zhu 1 , David Scanlon 1 , Chris Pickard 2 1 Department of Chemistry, Inorganic Chemistry Laboratory, University of Oxford, Oxford OX1 3QR, UK 2 Department of Chemistry, Physical and Theoretical Chemistry Laboratory, University of Oxford, Oxford OX1 3QZ, UK Low-cost, highly scalable batteries are crucial for grid-storage that underpins the wide-adoption of sustainable energy. Historically, the discovery of cathodes materials had led to significant advances in the field of Li-ion batteries. Coming up with new cathode systems is an experimentally challenging task, which can be accelerated by via computational searches. Polyanion-based materials, such as LiFePO4, typically have lower theoretical capacities than their oxide-based counterparts, yet the richness in charge and geometry among different polyanions allows tuning key cathode parameters through structural-property relationships. Higher capacities are achievable if multi-electron redox (such as in ε-VOPO4 1 ) or anionic redox can be incorporated. We have developed procedures for mining polyanionic units from databases of inorganic structures, and subsequently evaluating their potential as building blocks for cathode materials. The focus on unexplored chemical spaces mean traditional database-centric structure prediction approaches are less applicable. Instead, ab initio random structure searching (AIRSS) 2–5 is employed to locate the lower energy structures in underexplored chemical spaces from only the desired compositions and polyanion units as the inputs. Having a comprehensive table of all known polyanions would also benefit other field of solid-state materials beyond batteries. References 1. Siu, C.; Seymour, I. D.; Britto, S.; Zhang, H.; Rana, J.; Feng, J.; Omenya, F. O.; Zhou, H.; Chernova, N. A.; Zhou, G.; Grey, C. P.; Piper, L. F. J.; Whittingham, M. S. Enabling Multi-Electron Reaction of ε-VOPO4 to Reach Theoretical Capacity for Lithium-Ion Batteries. Chem. Commun. 2018, 54 (56), 7802–7805. 2. Pickard, C. J.; Needs, R. J. Ab Initio Random Structure Searching. Journal of physics. Condensed matter : an Institute of Physics journal 2011, 23 (5), 053201–053201 3. Lu, Z.; Zhu, B.; Shires, B. W. B.; Scanlon, D. O.; Pickard, C. J. Ab Initio Random Structure Searching for Battery Cathode Materials. J. Chem. Phys. 2021, 154 (17), 174111. 4. Zhu, B.; Scanlon, D. O. Predicting Lithium Iron Oxysulfides for Battery Cathodes. ACS Appl. Energy Mater. 2022, 5 (1), 575–584. https://doi.org/10.1021/acsaem.1c03094. 5. Zhu, B.; Lu, Z.; Pickard, C. J.; Scanlon, D. O. Accelerating Cathode Material Discovery through Ab Initio Random Structure Searching. APL Materials 2021, 9 (12), 121111.
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