METHOD FOR PRODUCING HALIDE SOLID ELECTROLYTE, HALIDE SOLID ELECTROLYTE, POSITIVE ELECTRODE MATERIAL, AND BATTERY

A production method for a halide solid electrolyte of the present disclosure includes (A) halogenating a raw material including a carbonate of at least one metal element selected from the group consisting of Li and M by heat treatment to obtain a halide solid electrolyte containing Li, M, and X. The M is at least one element selected from the group consisting of metal elements (excluding Li) and metalloid elements, and the X is at least one selected from the group consisting of F, Cl, Br, and I.