Method for producing sulfide solid electrolyte and sulfur-based material

A method for producing a sulfide solid electrolyte containing a lithium element, a sulfur element, a phosphorus element, an iodine element and a bromine element, which comprises:

• mixing and grinding lithium sulfide and lithium bromide by a slurry method in the presence of an organic solvent resulting in a ground mixture with no lithium bromide,
• wherein in powder X-ray diffractometry using a CuKa ray of the ground mixture prepared by mixing and grinding lithium sulfide and lithium bromide, a diffraction peak derived from lithium bromide is not observed,
• followed by adding phosphorus sulfide and lithium iodide thereto and reacting them to for form a powder, and
• heating the resultant powder to provide a sulfide solid electrolyte.