Characterization of Layered Rocksalt Type Cathode/Sulfide Solid-Electrolyte Interface Using a Model Film Battery and in Situ X-Ray Diffraction

Sulfide based ionic conductors are attractive solid electrolytes for all solid-state batteries owing to their high ionic conductivity and high reliability. One of remaining issues is to stabilize the lithium (de)intercalation reaction at the cathode/sulfide electrolyte interface in high potential regions for the development of all solid state batteries with high energy density. Here we investigated the interfacial reactions between LiMO2 (M= Ni, Mn, Co) and amorphous Li3PS4 using a model film battery. LiMO2 cathode/LiNbO3 buffer layer/Li3PS4 films were fabricated by pulsed laser deposition, and Li metal anode was deposited by vapor deposition. The thin-film battery had a well defined interface suitable for elucidating electrochemical reactions. The relationship between electrochemical properties and crystal structural changes were discussed based on crystal structures determined by in situ X-ray diffraction (XRD) measurements conducted under high voltage operation.