In situ lithiation of TiS2 enabled by spontaneous decomposition of Li3N

We report on a novel method for in situ lithiation of lithium free TiS2 using Li3N in an all-solid-state battery configuration. This method was tested using a Li3N–TiS2–80Li2S:20P2S5 composite positive electrode and an indium metal negative electrode. It is shown that approximately 37% of Li3N spontaneously decomposes during composite preparation regardless of the composition. Solid-state battery cells built with a 3:1 stoichiometric ratio of Li:Ti demonstrated a high 1st cycle charge capacity of 287 mAh g−1, 20% greater than the theoretical capacity of TiS2 at 239 mAh g−1. The difference provides an excess capacity in the indium metal negative electrode.

► This report demonstrates the feasibility of using Li3N to lithiate TiS2 in a cell without a readily available source of lithium ions.
► Li3N can be added to the composite material until the desired degree of lithiation is achieved.
► A 3:1 stoichiometric Li:Ti composite electrode demonstrated a 287 mAh g−1 1st charge capacity, or 48 mAh g−1 greater than TiS2's theoretical capacity.
► Li3N in situ lithiation opens up the possibility of safely utilizing many lithium free electrode materials in all-solid-state batteries.