Unveiling Incompatibility of High Nickel Cathode With p‐xylene Solvent for Facile Wet‐Slurry Process in All‐Solid‐State Batteries

Abstract All‐solid‐state batteries (ASSBs) are considered one of the most promising next‐generation batteries due to their outstanding safety and superior energy density. For the commercial success of ASSBs, developing a scalable wet‐slurry‐based electrode manufacturing process is essential. In this regard, non‐polar solvents have been generally used in the wet‐slurry process with sulfide‐based solid electrolytes (SEs) to avoid their chemical crosstalk. Although many studies on the chemical compatibility between sulfide‐based SEs and non‐polar solvents have been conducted, to the best of the knowledge, an in‐depth understanding of the interfacial chemistry between those solvents and active materials is not fully elucidated. In this study, the chemical incompatibility of LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM) cathode with p‐xylene, a representative non‐polar solvent, through in‐depth analyses of cation mixing, Ni dissolution, and surface reconstruction is revealed. Contrary to expectations, severe interfacial challenges arise from the side reactions between NCM and p‐xylene, resulting in poor electrochemical properties in ASSBs. The origin of the decrease in electrochemical performances of the wet‐slurry‐based electrodes in ASSBs is unveiled, which can be addressed by employing a surface protective coating layer on NCM cathodes.