The effect of strain on the Li-storage performance of V2C and Nb2C: From first-principles study

Abstract

Upon using 2-dimensional (2D) materials as electrodes for Li-ion batteries, strain will be produced due to mechanical factors and Li-intercalation reactions, which changes the intrinsic Li-ion storage performance of the 2D electrodes. In this paper, we investigate the effect of strain on the Li-storage performance of 2D MXenes V2C and Nb2C from density functional theory calculations. The Li-adsorption energies, Li-ion migration energy barriers at lithiated/delithiated states are calculated under varied external strain conditions ranging from −5% to 5%. It is found that, at low Li-ion adsorption concentration, compressive strain is beneficial for both Li-ion adsorption and diffusion, while at high Li-ion adsorption concentrations Li-ion adsorption becomes not favored on V2C but favored on Nb2C under compressive strain. Tensile strain is in favor of Li-vacancy diffusion at high Li-ion adsorption concentrations.