Effect of concentration-driven magnetic phase changes on adsorption and diffusion in VSe2 monolayers: Implications for lithium-ion batteries

Abstract

A vanadium diselenide (VSe2) monolayer is a two-dimensional (2D) magnetic material that exhibits ferromagnetic ordering at room temperature and exceptional metal-ion storage capacity, making it useful in spintronics and energy storage applications. However, a robust correlation between the magnetic and electrochemical properties of VSe2 remains to be established. In this study, first-principles density functional theory calculations were performed to investigate the effect of increasing Li-ion concentrations on the magnetic properties, particularly the magnetic ground state of the VSe2 monolayer. The results indicate that, as the concentration of Li ions on the surface of VSe2 monolayer increases, magnetic phase transitions occur, leading to a shift from the intrinsic ferromagnetic (FM) state to antiferromagnetic (AFM) and non-magnetic ground states. Analyses of the diffusion properties of ferromagnetic and antiferromagnetic VSe2 monolayers revealed a considerable (∼71%) increase in the Li-ion diffusion energy barrier for the AFM state compared to the FM state. This implies that FM-VSe2 facilitates relatively faster diffusion of Li ions than AFM-VSe2. Therefore, the Li-ion concentration-induced phase change in the VSe2 monolayer leads to variable adsorption and diffusion characteristics, which will have significant implications for its use in Li-ion battery anodes.