A high conductive TiC–TiO2/SWCNT/S composite with effective polysulfides adsorption for high performance Li–S batteries

Abstract

Lithium-sulfur (Li–S) batteries have attracted more and more attention in recent years, as their theoretical capacity is several times larger than conventional lithium-ion batteries and they have a high energy density in secondary battery systems. In our work, a titanium carbide - titanium dioxide/single-walled carbon nanotube/sulfur (TiC–TiO2/SWCNT/S) cathode with high conductivity and effective polysulfides adsorption is prepared by a facile method for fabricating Li–S batteries. The batteries with this composite cathode show a good performance at 0.1 C due to relatively high utilization of sulfur, reaching 1338.6 mAh·g−1 specific capacity at first cycle and retaining 802.5 mAh·g−1 after 100 cycles. Meanwhile, it presents an excellent rate performance with 711.2 mAh·g−1 at 4 C, and recovers to 1006.9 mAh·g−1 when the current returns to 0.1 C. Also a slow capacity decay (0.045% decay rate per cycle) is observed at 1 C. These results suggest that a small amount of SWCNT can increase the conductivity of the whole composite to a great extent, and the strong adsorption ability of TiO2 increases the cycle life. This work offers an efficient and low-cost strategy to obtain high performance batteries with great potential for commercial applications.