Metallic two-dimensional Cu2Si monolayer as promising anode materials for lithium and sodium ion batteries, a first principles study

Two-dimensional (2D) materials have attracted much attention as anode materials for lithium ion batteries. However, most of the 2D materials are semiconductors with limited electron transportation. In this paper, the electronic properties of Cu2Si monolayer and adsorption and diffusion of Li/Na on Cu2Si monolayer were investigated by the density functional theory. The Cu2Si monolayer shows metallic characteristics. The adsorption energies are around -2.5 eV, which is stronger than those of Li/Na absorbed on other 2D materials. In addition, the diffusion energy barriers are 0.15 and 0.11 eV for Li and Na diffuses on Cu2Si monolayer, respectively, indicating that Cu2Si monolayer can be fast charged/discharged. These results indicate that Cu2Si monolayer can be a promising anode material for lithium and sodium ion batteries.