Monolayer SrB8 as potential highly efficient electrocatalysts for lithium-sulfur batteries: First principle study

Abstract

Lithium-sulfur batteries have extremely high theoretical specific capacity and energy density, but their commercial application has been hindered by the shuttle effect, poor cathode conductivity and sluggish reaction kinetics during charging and discharging. The proposed two-dimensional (2D) multifunctional sulfur host material is an effective strategy to solve the above problems. In this work, the anchoring and catalytic properties of SrB8 monolayer for S8 and Li2Sn (n = 1, 2, 4, 6, 8) were studied by means of density functional theory. The results show that SrB8 has moderate adsorption energy for lithium polysulfides (LiPSs), and can effectively prevent the dissolution of long-chain LiPSs into the electrolyte without destroying the integrity of the clusters. The metallic feature of the SrB8 monolayer is well preserved during the adsorption process, thus ensuring a high electric conductivity at the cathode. At the same time, the SrB8 monolayer has a lower decomposition barrier and diffusion barrier for Li2S molecules, which significantly improves the charge and discharge rate of lithium-sulfur batteries. The results show that SrB8 monolayer is a promising multifunctional host material for lithium-sulfur batteries.