Theoretical prediction of O-B2S2 monolayer as two-dimensional sodium-ion battery anode material by first-principles calculations

Abstract

Sodium-ion batteries (SIBs) have attracted considerable interest due to their affordability and plentiful natural resources. Nonetheless, their primary technical hurdle lies in pinpointing appropriate materials for anodes. This research involved modifying the surface atoms of the unaltered B2S2 monolayer with O atoms as external elements and methodically examining the new two-dimensional, buckling-structured O-B2S2 monolayer through fundamental calculations to evaluate its efficacy in sodium-ion batteries. Initial simulations of molecular dynamics and computations of phonon dispersion relationships have proven its robust stability, offering theoretical backing for the preparation procedure. Notably, the O-B2S2 monolayer preserves its high metal content even when it absorbs sodium ions of varying concentrations, and this absorption of sodium atoms markedly enhances the O-B 2 S 2 monolayer's conductivity. Furthermore, the O-B 2 S 2 monolayer twodimensional system, utilizing the climbing image-nudged elastic-band (CI-NEB) technique, demonstrates reduced sodium diffusion barriers (0.179 eV) and diminished average open circuit voltages (0.46 eV) throughout the charging and discharging phases. Within this framework, the O-B2S2 monolayer's twodimensional storage ability can achieve 910.53 mAh/g, exceeding that of numerous other two-dimensional substances, all within the voltage spectrum that restricts dendrite expansion. To sum up, the O-B2S2 monolayer is notable for its substantial sodium storage, minimal diffusion barrier, and appropriate open circuit voltages, positioning it as an ideal anode material for advanced sodium-ion batteries.