Structural and electrochemical properties of Ta_n+1C_n MXene anode materials for metal-ion batteries

With the utilization of alkali metal-ion batteries, the development of electrode materials with sufficient electrical conductivity, ultra-fast ion-diffusion capability and high storage capacity remains challenging. In this work, two-dimensional Tan+1Cn (n = 1, 2 and 3) MXenes as anode materials for rechargeable metal-ion batteries were investigated using the density functional theory approach. The results show that Tan+1Cn MXenes have excellent adsorption properties and electronic conductivities for Li, Na, K, Mg and Ca atoms. Ultra-low barriers to the diffusion of alkali metal ions hold promise for high performance in ultra-fast charging and discharging. The open-circuit voltages and maximum capacities of Tan+1Cn MXenes indicate that they are very promising candidates for the anode materials of Li, Na, K, Mg and Ca-ion batteries. Tan+1CnO2 MXenes also have stable electronic structures, excellent adsorption energies and diffusion rates for Li+ and Na+ ions. These findings may provide theoretical guidance for the design of novel MXene-based composite energy materials.