UNIFORM ORGANIC-CERAMIC COMPOSITES FOR SOLID-STATE BATTERIES

A solid-state electrolyte for a lithium battery that includes a hard-inorganic electrolyte and at least two soft electrolytes (SEs), where the melting point of the solid-state electrolyte is less than the melting point of a highest melting SE included in the solid-state electrolyte. The SEs include ammonium or phosphonium salts of closo-borates and can include lithium closo-borates salts. The hard-inorganic electrolyte is a lithium thiophosphate (LPS), where the plurality of SEs is melt-diffused throughout the homogeneous combined hard-inorganic electrolyte and a plurality of SEs at a temperature below the highest melting point SE, generally below 100° C. The relative density of the solid-state electrolyte is greater than 90 percent.