Effect of the functional groups on the electrochemical properties of the Mo2V2C3Tx MXene as anode in metal ion batteries

In this work, we investigate the structural stability, ion mobility, and charge storage mechanisms of the double transition metal Mo₂V₂C₃T_x MXenes using DFT calculations. The ion intercalation mechanism was explored, and the role of O, F, Cl, Br, and OH functional groups on the Mo₂V₂C₃T_x anode for Li, Na, K, Mg, and Ca batteries was inspected. Electrochemical performance was evaluated using the theoretical open-circuit voltage (OCV) method, which determined the gravimetric capacity of each terminated Mo₂V₂C₃T_x for each ion. Notably, the O-terminated material demonstrates the highest gravimetric capacity of 222.1 mAh/g. In contrast, an unexpected outcome was achieved by the Br-terminated Mo₂V₂C₃T_x, which exhibits an elevated gravimetric capacity of 165.4 mAh/g for Ca-based batteries, thereby enhancing the Ca diffusion. Additionally, Mo₂V₂C₃O₂ as an anode for Li- and Na-batteries, exhibits a gravimetric capacity of 148.1 mAh/g and displays good electrochemical behavior. Finally, the Mo₂V₂C₃Cl₂ exhibits promising electrochemical behavior, and the energy barriers for alkali ions are comparable to the –O, -Br, and -Cl terminated Mo₂V₂C₃T_x. Our findings suggest that Mo₂V₂C₃T_x is a promising anode for alkali-ion batteries.