Lithium intercalation into TiS2 cathode material: phase equilibria in a Li–TiS2 system

Abstract

Lithium-intercalated titanium disulfide Li x TiS2 had been extensively studied as prototypical cathode material for high-energy-density reversible lithium batteries with moderate voltage. Today, this phase is one of the leading candidates for all-solid-state lithium batteries with durable high energy and high rate performance. However, fundamental knowledge of Li+ insertion into TiS2 is still incomplete; available information on the phase diagram of the Li–TiS2 system is limited by x = 1 due to difficulties in preparing lithium-rich equilibrated samples. The goals of this work were to re-examine Li x TiS2 single phase boundaries and to clarify the existence of lithium-rich intercalates with x > 1. А new preparation technique was developed to obtain 1T-Li x TiS2 samples as good-quality equilibrated products with desirable lithium content. Phase equilibria in a quasibinary Li–TiS2 system were studied by X-ray diffraction, emf measurements (25 °C) and thermal analysis (25–350 °C) over a wide range of Li:Ti ratios (0 to 4).