Theoretical Investigation of the Structure−Property Correlation of MXenes as Anode Materials for Alkali Metal Ion Batteries

MXenes have been extensively explored as anode materials in Li, Na, and K ion batteries. However, the correlation between structural properties of MXenes and their electrochemical performances has not been fully understood. In the present study, the structural properties of five typical M₃C₂O₂ (M = V, Ti, Nb, Hf, and Zr) and the adsorption and diffusion properties of Li, Na, and K atoms on them are studied in detail by using density functional theory calculations. Based on our calculated results, we found that different transition-metal-based M₃C₂O₂ possessed highly distinct structural properties, which significantly influence the adsorption and diffusion behaviors of Li, Na, and K atoms on them. Thus, it can be concluded that the performance of M₃C₂O₂-based anode materials can be optimized by selecting an appropriate transition metal or applying biaxial strain to directly change the lattice constant of specific M₃C₂O₂. Overall, our results will be helpful for efficient selection and design of effective M₃C₂O₂-based anode materials for Li, Na, and K ion batteries, which may also offer insight for selection and design of other two-dimensional material-based electrode materials in batteries.