Explore the feasibility of Janus 2H-VSeTe monolayer as anode material for Li ion battery

Abstract

Two-dimensional (2D) materials as potential energy storage systems have received extensive attention due to their high energy density and rate performance. Here, the electronic properties and feasibility of Janus 2H-VSeTe monolayer as LIBs anode material are systematically investigated using the first-principles calculations. No imaginary frequency in the phonon spectrum and the absence of obvious deformation simulated by AIMD simulations at 300 K prove the dynamic and thermal stability of Janus 2H-VSeTe monolayer, respectively. The pure Janus 2H-VSeTe monolayer exhibits a small direct band gap semiconductor character. The Li atom adsorption can result in the increase of electronic states near E_f and a transform of metallic behavior, ensuring good conductivity for the Janus 2H-VSeTe monolayer. On the other hand, the adsorbed Li atoms are fully ionized to ensure the charge and discharge process by the Bader analysis. Through the climbing-image nudged elastic band method, two possible migration paths are considered on the Se and Te surfaces, respectively. The lowest potential barriers are 0.159 eV and 0.188 eV, respectively, which proves that there is a high ion migration rate during charge and discharge process. The OCV and multi-layer Li atoms adsorption suggest that the corresponding specific capacity is 416 mA h g⁻¹ for the Janus 2H-VSeTe monolayer, which reveals that Janus 2H-VSeTe monolayer is one of the feasible candidates for LIBs anode materials.