First-principles studies of the two-dimensional 1H-BeP2 as an electrode material for rechargeable metal ion (Li+, Na+, K+) batteries

Abstract

Finding high-performance electrode materials is one of the most effective ways to improve the energy density of current metal-ion batteries. MoS2-like 1H-BeP2 is intrinsically metallic before and after adsorption of metal ions and shows good electrical conductivity. Based on present first-principles calculations, 1H-BeP2 could be regarded as a potential promising electrode material for metal-ion batteries. Importantly, the fully Li (Na) phase X4BeP2 (X = Li, Na) for 1H-BeP2 exhibits a high theoretical capacity of 1510 mAh/g with up to one layer of potassium ions, outperforming most previously reported 2D candidates. Meanwhile, it is found that the open circuit voltage and diffusion barrier of 1H-BeP2 after fully adsorbed metal ions were as low as 0.17 V, 0.22 V and 0.34 V, respectively, which was surprising. Present studies would be helpful for the exploration of novel 1H-BeP2 type electrode materials for metal-ion batteries.