In accordance with one aspect of the present invention, a cathode composition is provided that includes at least one transition metal or a transition metal salt, wherein the transition metal is at least one selected from the group consisting of nickel, iron, cobalt, chromium, manganese, molybdenum, and antimony; an alkali metal halide; a salt comprising an alkali metal halide and a metal halide; and a metal polysulfide compound MSn wherein M is a metal and n is an integer equal to or greater than 2. The salt comprising an alkali metal halide and a metal halide has a melting point of less than about 300° C. An energy storage device comprising the electrode composition is also provided.