Formation of Intimate Interfacial Contact between The NCM and Li₆PS₅Cl Solid Electrolyte for All-Solid-State Batteries

All-solid-state batteries (ASSBs) with sulfide-based solid electrolytes (SEs) have been considered the most promising next-generation energy storage system due to their high energy density. However, mechanical instability such as initial insufficient physical contact and physical contact loss during cycling at the cathode active materials/solid electrolyte interface impede the practical use of ASSBs. Here, we report high-performance ASSBs using a Ni-rich NCM as cathode active materials coated with argyrodite-type sulfide solid electrolyte through the mechano-fusion method. The uniformly coated solid electrolyte layer guarantees solid physical contact between cathode active materials and solid electrolytes, enabling sufficient ion transport pathways. Furthermore, the firmly attached solid electrolyte does not detach from NCM when the cathode active material shrinks during de-lithiation. Making intimate initial physical contact and maintaining physical contact repress the interface resistance effectively. As a result, a full cell with argyrodite-coated NCM shows significantly enhanced electrochemical performances.