Kinetic Analysis of Cathode–Solid Electrolyte Interface in All-Solid-State Batteries

Abstract

High interfacial impedance hinders the development of all-solid-state batteries. While thermodynamic analyses offer stability insights, they overlook the kinetic effects that dominate during operation. Here, we use a machine learning interatomic potential to perform long-timescale molecular dynamics simulations of various cathode/solid electrolyte (SE) interfaces, including sulfide, chloride, and oxide SEs with layered \ce{LiCoO2}. Our simulations reveal three primary kinetic mechanisms driving impedance: (1) interfacial reactions, especially with sulfide SEs, forming poorly conducting interphases; (2) the formation of lithium-depleted regions that reduce available \ce{Li+} pathways; and (3) cation inter-diffusion, which obstructs lithium transport channels and degrades the cathode. These findings underscore the critical role of kinetics in interfacial stability and establish machine learning-driven atomistic modeling as a powerful tool for designing next-generation solid-state batteries.