Prof. Vikram DESHPANDE joined the faculty of Engineering at the University of Cambridge as a lecturer in 2001 and was promoted to a professorship in Materials Engineering in 2010. He has written in excess of 280 journal articles in experimental and theoretical solid mechanics. He serves on the editorial boards of a number of journals in mechanics and biomechanics including the Journal of the Mechanics and Physics of Solids, Modelling and Simulation in Materials Science and Engineering, and the Proceedings of the Royal Society, London. He has been awarded numerous medals including the 2020 Rodney Hill Prize in Solid Mechanics, the 2022 William Prager Medal, the 2022 ASME Koiter Medal, and elected Fellow of the Royal Society, London.
Failure of all solid-state Li-ion batteries
Solid-state batteries comprising a ceramic electrolyte and Li metal anode have the potential to deliver enhanced safety along with higher specific energies compared to liquid electrolyte Li-ion batteries. However, stiff, and strong ceramic electrolytes can suffer short circuits resulting from the penetration of Li filaments through the ceramic at charging currents above a critical current density. This is remarkable since the yield strength of Li is on the order of a few MPa while the ceramic electrolytes have strengths of many 100s of MPa and moduli in the GPa range. The failure of these Li-ion cells occurs via two interconnected processes: (i) formation of voids at the Li electrode/electrolyte interface and (ii) growth of Li filaments, that emanate from the vicinity of these voids, into the electrolyte. We shall present coupled electrochemical-mechanical variational principles to understand how the electrochemistry of these cells drives mechanical failure. Our focus is on developing an understanding of how well-established ideas such as Butler-Volmer kinetics need to be modified in the context of these solid-state batteries and associated numerical techniques. The numerical solution of the variational principles provides insights into experimental observations, but numerous uncertainties remain with regards to the microscale properties of the Li and solid electrolytes as well as the mechanisms coupling mechanical deformations and electrochemistry.