In Situ Synthesis of Vacancy-Rich Titanium Sulfide Confined in a Hollow Carbon Nanocage as an Efficient Sulfur Host for Lithium–Sulfur Batteries

The practical application of lithium–sulfur batteries (LSBs) is partially impeded by large volume variation, severe shuttle effect, and inferior electrical conductivity of sulfur. On this account, a template-free arc-discharge method for the synthesis of TiS_x (1.5 < x < 2)@HCN (hollow carbon nanocage) as an efficient sulfur host is developed for LSBs. TiS_x@HCN can accommodate the volume changes of active materials and inhibit the shuttle effect of lithium polysulfides (LiPSs). Theoretical calculation shows that the defective titanium sulfide accelerates the conversion of long-chain LiPSs to intermediate species and promotes the redox reactions. As a consequence, the resulting hybrid cathode composited with sulfur exhibits excellent electrochemical performances. A reversible capacity of 1118.6 mA h g^–1 is obtained under 0.1 C with a slow capacity decay of 0.108% per cycle for 200 cycles. The synthetic strategy provides a facile platform for the synthesis of nanocomposite materials.