Abstract: Methods for recycling solid electrolytes include contacting the solid electrolyte with a metal halide in a solvent to produce a mixture comprising a metal sulfide, an alkali metal salt, and undissolved material. The undissolved material is removed from the mixture to form a solution, and then the solvent is removed to form a composite that includes a metal sulfide and an alkali metal salt.

Abstract: Methods for purifying metal sulfides include combining an alkali metal sulfide and composites that include a metal sulfide in an aprotic solvent, filtering undissolved solids from the mixture, and adding a secondary sulfide to the solution to precipitate the highly pure metal sulfide. The purified metal sulfides may be used in the production of solid-state electrochemical cells.

Abstract: Methods for producing metal sulfides generally include combining an alkali metal sulfide and a metal halide in an aprotic solvent to produce a mixture that includes an alkali metal halide and a metal sulfide. Additional methods include combining a first alkali metal sulfide, a second alkali metal sulfide, and a metal halide in an aprotic solvent to produce a mixture that includes a first alkali metal halide, a second alkali metal halide, and a metal sulfide. The methods may include adding a second solvent to cause an alkali metal halide to precipitate out of the mixture and improve the purity of the metal sulfide.