The First-Principles Prediction of Two Dimensional Monolayer Puckered WCAZ2 as the Anode Material of Li-ion Batteries

Abstract

Searching for new high performance anode materials for Li-ion batteries(LIB) have become a critical issue in the current development of power source storage. In this paper, we theoretically predict a new kind of two dimensional transition metal carbide structure WC2, which is similar to MXene materials. The monolayer puckered WC2 is rather thermodynamically stable which can be demonstrated by the none imaginary frequency in the phonon spectrum and the entire structure after 5 ps ab initio molecular dynamic simulation at 300 K. The monolayer WC2 has the metallic character, hence ensures the fast electron transport during the lithiation/delithiation process. The moderate average adsorption energy of Li atoms (2.16 eV) and low diffusion energy barrier of Li (0.34 eV) on the surface prove that the monolayer WC2 has high charge/discharge rate and is suitable for the LIB anode. The maximum gravimetric capacity of numerous Li atoms adsorbed monolayer WC2 reaches 516 mA h/g, which is comparable to that of other MXene anodes. The small volume variation ratio(< 5 %) of the WC2 anode ensures the excellent cycling performance for LIBs. The electron transfer and orbital hybridization between Li and the monolayer WC2 indicate its excellent properties. Thus, the monolayer WC2 should be a promising anode material for the LIBs.