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 materials, 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 materials 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.