HALIDE SOLID ELECTROLYTE PRODUCTION METHOD, HALIDE SOLID ELECTROLYTE, POSITIVE ELECTRODE MATERIAL, AND BATTERY

A production method for a solid electrolyte of the present disclosure is a production method for a halide solid electrolyte containing Li, Ti, M, and X. M is at least one element selected from metal elements (excluding Li and Ti) and metalloid elements, and X is at least one selected from F, Cl, Br, and I. The production method includes: (A) performing halogenation treatment on at least one Li source selected from a simple oxide and a simple carbonate of Li, at least one Ti source selected from a simple oxide and a simple carbonate of Ti, and at least one M source selected from a simple oxide and a simple carbonate of M, to obtain simple halides of Li, Ti, and M, respectively; and (B) synthesizing the halide solid electrolyte using the simple halides of Li, Ti, and M.