Self-templated preparation of hollow mesoporous TiN microspheres as sulfur host materials for advanced lithium-sulfur batteries

Although lithium-sulfur (Li-S) batteries are an advanced energy storage system, their development has been impeded due to poor cycling stability and low sulfur utilization. Hollow TiN microspheres with a porous shell were prepared to host sulfur (TiN-S) for use as a Li-S battery cathode. The TiN-S electrode delivered a high capacity of 1206.1 mA h/g at 0.1 C, and a narrow value domain of 1218.2 +/- 17.7 mA h/g was obtained from initial discharge capacities of 9 cells. Furthermore, a capacity of 623.3 mA h/g (with a retention of 67.5%) was maintained after 300 progressive cycles at 1 C. The superior cycling performance of the TiN-based cathode can be ascribed to the following: (1) TiN improved the electrical conductivity of the cathode, effectively increasing the active sulfur utilization; (2) the hollow TiN microspheres with pores restricted the soluble polysulfides by both chemical and physical interactions; (3) the large void of the spherical cavity in TiN could accommodate the change in volume of the cathode during the discharge-charge processes.