METHOD FOR PRODUCING SOLID ELECTROLYTE POWDER, AND METHOD FOR PRODUCING ALL SOLID STATE BATTERY

A method for producing a solid electrolyte powder includes preparing a mixed solution by adding a poor solvent to a good solvent solution that contains a good solvent and a solid electrolyte that contains an alkali metal element and/or an alkaline earth metal element, Sn and S; removing at least some of the good solvent from the mixed solution to precipitate solid electrolyte particles; and drying the solid electrolyte particles to obtain a solid electrolyte powder. The ratio of the volume of the poor solvent relative to the volume of the good solvent (volume of poor solvent/volume of good solvent) is 5 or more.