Sulfur Immobilizer by Nanoscale TiO2 Trapper Deposited on Hierarchical Porous Carbon and Graphene for Cathodes of Lithium-Sulfur Batteries

Lithium-sulfur (Li-S) batteries are the promising candidate for future energy storage systems due to their high specific capacities and energy densities. However, shuttle effect of the soluble polysulfides severely affects the cycle stability and thus restricts the application of the batteries. Here, a preparation of the titanium oxide (TiO2) nanoparticles uniformly deposited on hierarchical porous carbon (HPC@TiO2) as an efficient sulfur host is reported. The large specific surface area (1016.5 m(2) g(-1)) and high pore volume of the HPC@TiO2 host can buffer the volume expansion of the loaded sulfur. The HPC@TiO2@S cathode is further wrapped with the TiO2 nanoparticles interspersed graphene sheets (G/TiO2), which can improve the electrical conductivity of the electrode and suppress the dissolution of polysulfides. As a result, polysulfides are well confined in the G/TiO2-coated HPC@TiO2@S cathode through a synergistic combination of the G/TiO2 coating and the HPC@TiO2 host. The resultant G/TiO2-coated HPC@TiO2@S cathode with a sulfur loading about 2.4 mg cm(-2) delivers a high reversible capacity of approximate to 919 mAh g(-1) after 80 cycles at 0.2 C, and a satisfactory capacity of approximate to 717 mAh g(-1) is retained after 200 cycles at 0.5 C.