Elucidating Interfacial Stability of the Electrolyte/Cathode Interfaces in Solid-state Batteries

Emerging solid-state electrolytes (SSEs) with superior ionic conductivity have been developed for all-solid-state batteries (ASSBs). However, most SSEs experience noticeable interfacial incompatibility with most conventional cathodes, so ASSBs are subject to significant cycling degradation. Through experimental characterization techniques, it is hard to clarify the main interfacial degradation factors, identify the decomposition products, and allow an atomic scale visualization of interfacial reactions. In this study, <i>ab-initio</i> calculations are used to determine phase, chemical and electrochemical stability of various prominent SSEs and cathodes as a function of the state-of-charge (SoC). Specifically, SSE/cathode interfaces of superior oxide-, sulfide-, and halide-based SSEs and conventional layered-, spinel-, and olivine-structure cathodes are investigated. Factors controlling interfacial stability are revealed and stable SSE/cathode interfaces are identified. The <i>ab-initio</i> understanding of the SSE/cathode interfacial stability allows the development and design of a variety of stable solid-to-solid interfaces.