An all-solid-state lithium battery, thermo-electromechanical activation of Li2S in sulfide based solid state electrolyte with transition metal sulfides, and electromechanical evolution of a bulk-type all-solid-state iron sulfur cathode, are disclosed. An example all-solid-state lithium battery includes a cathode having a transition metal sulfide mixed with elemental sulfur to increase electrical conductivity. In one example method of in-situ electromechanically synthesis of Pyrite (FeS2) from Sulfide (FeS) and elemental sulfur (S) precursors for operation of a solid-state lithium battery, FeS+S composite electrodes are cycled at moderately elevated temperatures.