Two-dimensional VSe2/CNT functional materials boosted polysulfide conversion for high stability lithium-sulfur battery

Abstract

Lithium-sulfur batteries are considered one of the most likely next-generation batteries to be commercialized because of their high theoretical energy density, but severe shuttle effects affect their practical application. Herein, two-dimensional layered vanadium diselenide is combined with carbon nanotubes (2D-VSe2/CNT) to act as advanced sulfur host to suppress the shuttling of lithium polysulfides. 2D-VSe2/CNT possesses sulfiphilic surface and high electrical conductivity, which is beneficial for chemisorption of polysulfides as well as the nucleation and growth of Li2S. In addition, the fast kinetic response is confirmed by the higher current density and the large lithium ion diffusion coefficient. Furthermore, VSe2/CNT/S cathode shows ultra-stable cycling performance with a capacity decay rate of only 0.03% after 500 cycle at 0.5C.