Chemo-electrochemical Evolution of Cathode–Solid Electrolyte Interface in All-Solid-State Batteries
Patrick Kwon, Carlos Juarez‐Yescas, Hyewon Jeong, Saeed Moradi, Elizabeth Gao, Debbie Lawrence, Beniamin Zahiri, Paul V. Braun
Abstract
The stability of the interface between the cathode and the solid electrolyte (SE) has been found to be a key determinant of solid-state battery (SSB) performance. While interfacial failure from electrochemical cycling has been studied, temperature effects on the chemical and electrochemical evolution of interface properties are not well-understood. We utilize a dense additive-free LiCoO 2 cathode, which provides controlled morphology and crystallography, and well-known high voltage halide SEs (Li 3 InCl 6 and Li 3 YCl 6 ) to eliminate the need for cathode coating to explore the nature of interface deterioration induced by operating at up to 100 °C. By promoting temperature-induced accelerated interfacial failure, we show that at elevated temperatures (>60 °C) and higher states of charge, a significant chemo-electrochemical contribution to interfacial resistance results in rapid cell performance degradation. Our findings show that beyond the well sought-after SE electrochemical voltage stability, the atomic-scale restructuring of the cathode surface interfaced with the SE must be considered when designing stable interfaces.