Theoretical study on sodium storage properties of two-dimensional magnetic VS2 monolayer

In order to broaden the selection range of anode materials for sodium ion batteries, improve the overall performance of batteries and commercial application potential. This study assessed the potential of monolayer VS₂ as an anode material using first-principles calculations. Through ab initio molecular dynamics simulations,the thermal stability of the VS₂ monolayer was verified. CI-NEB calculations revealed that sodium ions diffuse efficiently on the VS₂ monolayer, with a diffusion barrier of approximately 0.12 eV. Calculations of the density of states indicate that the VS₂ monolayer is intrinsically metallic, implying excellent rate performance. By calculating Na adsorption behavior on the VS₂ monolayer, we determined that the minimum open-circuit voltage range is 0.01 V with a maximum Na storage capacity of 932 mAh/g. During charge/discharge, the magnetism of the VS₂ monolayer changes due to variations in V-d orbital occupancy. Our study provides new ideas for screening sodium-ion battery anode materials. It also proposes a novel approach to monitor battery state-of-charge states based on changes in material magnetic moments.