Rational design of intrinsic and defective BGe monolayer as the anode material for Li-ion batteries

Abstract

The rational design of high-performance anode materials is an effective strategy to expedite the development of next-generation lithium-ion rechargeable batteries (LIBs). In this work, the first-principles calculation method is applied to systematically investigate the adsorption and diffusion behaviors of Li ions on the intrinsic and defective BGe monolayer, as well as the application prospects of such materials acting as anode materials for LIBs. Our results show that intrinsic planar BGe monolayer has the advantages of high structural stability, distinct metallic feature and strong interaction with Li. In addition, Li migration on the BGe surface shows a low diffusion barrier (0.32 ​eV), which could guarantee a rapid charging/discharging capability. Interestingly, the presence of the single B vacancy defect weakens the adsorption strength of Li ion in the defective regions due to the charge redistribution. Correspondingly, the defect slightly impedes the diffusion performance, resulting in an increased energy barrier for Li ion (0.44 ​eV) to escape the defective regions. On the other hand, the intrinsic BGe monolayer could be lithiated into BGeLi3 with a theoretical specific capacity of 1927 ​mA ​h ​g−1. The moderate open-circuit voltage and the flexible structural stability with negligible volume change further enhance the reversibility of BGe anode materials. All these results provide a robust foundation for the rational design of BGe monolayer as an efficient anode material for LIBs.