Theoretical study of highly efficient VS2-based single-atom catalysts for lithium–sulfur batteries

Abstract

Lithium–sulfur (Li–S) batteries have become a research hotspot due to their high energy density. However, they also have certain disadvantages and limitations. To enhance the performance of Li–S batteries, this study focuses on the utilization of transition metal (TM)-embedded vanadium disulfide (VS₂) materials as cathode catalysts. Using density functional theory (DFT), comprehensive calculations and atomic-level screening of ten TM atoms were conducted to understand the underlying mechanisms and explore the potential of TM@VS₂ catalysts for enhancing battery performance. The computational results indicate that five selected catalysts possess sufficient bonding strength towards high-order lithium polysulfide intermediates by the formation of a significant covalent bond between S atoms in Li₂S_n and TM atoms, thereby effectively suppressing the shuttle effect. The Ni@VS₂ catalyst can effectively decrease the decomposition energy barrier of Li₂S in the charge reaction and can have an optimal Gibbs free energy at the rate-determining step among TM@VS₂ catalysts for the discharge reaction. This study elucidates the mechanism of VS₂-based transition-metal single-atom catalysts and provides an effective reference for the anchoring of TM atoms on other materials.