Computational Investigation of the Interfacial Stability of Lithium Chloride Solid Electrolytes in All-Solid-State Lithium Batteries

All-solid-state Li-ion batteries (ASSLIBs) with solid electrolytes (SEs) are promising next-generation batteries owing to their high energy density and high safety. Recently, lithium chloride SEs have attracted increasing attention because of their high ionic conductivity and broad electrochemical stability window. However, only a few studies have been reported for the application of lithium chloride SEs in high-energy ASSLIBs employing lithium metal anodes and high-voltage cathode materials. This study examines the interfacial stability of lithium chloride SEs toward lithium metal anodes and high-voltage cathode materials using first-principles calculations. Calculation results indicate the chemical instability of lithium chloride SEs toward lithium metal anodes. Metallic phases are formed by reduction reactions resulting in the continuous decomposition of lithium chloride SEs. In addition, lithium chloride SEs exhibit high reactivity toward high-voltage cathode materials, resulting in interfacial resistance by decomposition reactions. Computational screening is performed to explore coating materials to stabilize the interfaces, demonstrating that binary halides are appropriate for the anode and 54 compounds are discovered for the cathode. Among the coating materials for the cathode, several ternary oxides such as LiAl₅O₈, Li₂MoO₄, and LiTaO₃ are found to be promising for enhancing the interfacial stability between lithium chloride SEs and high-voltage cathode materials.