Hierarchical VS2 Nano-Flowers as Sulfur Host for Lithium Sulfur Battery Cathodes

Abstract

Lithium sulfur batteries (LSB) are considered to be one of the most promising energy storage technologies due to their high energy density, low cost and environmental friendliness. However, there are still many defects such as the shuttle effect of polysulfide, the non-conductivity of sulfur and the large volume change of sulfur cathode leading to cyclic decay and instability. To overcome these challenges, in this study, we synthesized the VS2 nano-flowers (NFs) through the hydrothermal method, and then took them as the sulfur host. The VS2 NFs possess unique hierarchical structure and excellent electrical conductivity, which can promote Li+ and charge transmission, thus improving the reaction kinetics. Besides, the VS2 has excellent chemical interaction with polysulfides, which can efficiently suppress the migration of polysulfides and inhibit the shuttle effect. It possessed better cyclic stability compared with the pure sulfur counterparts. Impressively, the lithium sulfur batteries (LSBs) with VS2/S (1:5) cathodes whose specific capacity decay rate over 200 cycles at 0.2 C was ∼0.16% per cycle. It also greatly improved the sulfur utilization and the rate capability of LSBs. The above results demonstrate that the VS2 can enhance the cycling performance and has potential application in LSBs.