ELECTROLYTE SEPARATORS INCLUDING LITHIUM BOROHYDRIDE AND COMPOSITE ELECTROLYTE SEPARATORS OF LITHIUM-STUFFED GARNET AND LITHIUM BOROHYDRIDE

Set forth herein are compositions comprising A.(LiBH).B.(LiX).C.(LiNH), wherein X is fluorine, bromine, chloride, iodine, or a combination thereof, and wherein 0.1≤A≤3, 0.1≤B≤4, and 0≤C≤9 that are suitable for use as solid electrolyte separators in lithium electrochemical devices. Also set forth herein are methods of making A.(LiBH).B.(LiX).C.(LiNH) compositions. Also disclosed herein are electrochemical devices which incorporate A.(LiBH).B.(LiX).C.(LiNH) compositions and other materials.