Screening MXenes for novel anode material of lithium-ion batteries with high capacity and stability: A DFT calculation

Highlights: • Two novel high-capacity and high-stability anode materials for MXenes lithium-ion batteries. • A functional relationship that makes it easy to explore more MXenes materials. As an advanced battery technology, lithium-ion batteries have attracted extensive attention, especially in electric vehicles. However, low capacity and poor stability are two factors hindering more extensive application of lithium-ion batteries. Herein, we performed a screening study on MXenes including M₂C, MC₂, M₂N, MN₂ (M = Sc, Ti, V, Cr), in the search for promising lithium-ion battery anode materials by using density functional theory (DFT) calculations and ab initio molecular dynamic (AIMD) simulations. The theoretical capacities of Ti₂N and V₂N are 975 mAh/g and 924 mAh/g, respectively. Based on low deformation rate, and small energy variation, Ti₂N and V₂N have higher stability than that of graphite electrodes. The lower diffusion barrier accelerates the charging and discharging process of the battery. Considering their low diffusion barrier, excellent conductivity, high theoretical capacity, low deformation rate and high thermal stability, Ti₂N and V₂N are proposed as promising anode materials for lithium-ion batteries. The adsorption of lithium-ion belongs in the category of weak adsorption where the d-band center is negative. However, it is strong adsorption when the d-band center is positive. A linear relationship between the lithium-ion concentration and adsorption energy is developed for strong adsorption, which can be used to guide the design of high-capacity electrode materials.