Computational study on two-dimensional transition metal borides for enhanced lithium-sulfur battery performance: Insights on anchoring, catalytic activity, and solvation effects

Abstract

The controlled modulation of surface functional groups, in conjunction with the intrinsic structural characteristics of MXene materials, shows great potential in alleviating the shuttle effect and improving the sluggish reaction kinetics in lithium-sulfur batteries (LSBs). This study delves into the impact of surface functional groups (T = O, S, F, and Cl) on V₂B₂ MBene concerning sulfur immobilization and kinetic catalytic properties through meticulous first-principles calculations. The results reveal that the establishment of T-Li bonds within V₂B₂T₂ (T = O, S, F, and Cl) enhances the adsorption of lithium polysulfides (LiPSs). Moreover, the robust interactions between the T_p and V_d orbitals play a pivotal role in strengthening the T-V bond and reducing the energy barrier for Li₂S decomposition. Comparative analyses underscore the outstanding performance of V₂B₂O₂, showcasing a moderate adsorption strength for LiPSs, remarkable electrocatalytic activity for Li₂S decomposition (with an energy barrier of 0.42 eV), and a low Li₂S diffusion barrier (0.16 eV). These attributes facilitate effective anchoring and expedite reaction kinetics for LiPSs. Furthermore, the influences of solvation and temperature were found to have substantial impacts on the anchoring capability of V₂B₂T₂ except for V₂B₂O₂. This study establishes a critical theoretical framework and serves as a valuable reference for advancing MBene materials as cathodes for LSBs.

Keywords: Adsorption; Catalysis; Lithium–sulfur batteries; MXenes; Solvent effects; Temperature correction.