Two-dimensional van der Waals layered VSi2N4 as anode materials for alkali metal (Li, Na and K) ion batteries

A new class of highly stable two dimensional (2D) van der Waals (vdW) layered materials MA2Z4 (M = V/Cr/Mo, A = Si, Z = N/P) were realized. To determine a potential anode material in this class of 2D vdW layered ma-terials, the performance of 2D VSi2N4 as electrode material in metal (Li, Na and K) ion batteries was explored based on the first-principles calculations. The dynamic and thermal stabilities of 2D VSi2N4 were demonstrated. The conductivity of electrons during charging was shown. In addition, 2D VSi2N4 has a high charge-discharge rate based on a low diffusion barrier. The large capacity (1314.46, 985.84 and 492.92 mAh/g for Li, Na and K, respectively) and the corresponding open-circuit voltage change ranges are suitable for commercial anode ma-terials when the concentration of the Li, Na and K increases. Moreover, the maximum lattice change of 2D VSi2N4 is very small (0.8% for Li, 0.5% for Na and 0.6% for K) during charging and discharging. The 2D VSi2N4 is a promising electrode material for application in metal (Li, Na and K) ion batteries.