Halide Layer Cathodes for Compatible and Fast‐Charged Halides‐Based All‐Solid‐State Li Metal Batteries

Abstract

Insertion‐type compounds based on oxides and sulfides have been widely identified and well‐studied as cathode materials in lithium‐ion batteries. However, halides have rarely been used due to their high solubility in organic liquid electrolytes. Here, we reveal the insertion electrochemistry of VX ₃ (X=Cl, Br, I) by introducing a compatible halide solid‐state electrolyte with a wide electrochemical stability window. X‐ray absorption near‐edge structure analyses reveal a two‐step lithiation process and the structural transition of typical VCl ₃. Fast Li ⁺ insertion/extraction in the layered VX ₃ active materials and favorable interface guaranteed by the compatible electrode‐electrolyte design enables high rate capability and stable operation of all‐solid‐state Li‐VX ₃ batteries. The findings from this study will contribute to developing intercalation insertion electrochemistry of halide materials and exploring novel electrode materials in viable energy storage systems.