Monolayer BGe as a promising anode material with ultrahigh specific capacity for Mg-ion batteries

Abstract

Recently, the increasing development of electronic equipment has promoted the researches of rechargeable batteries. Magnesium-ion batteries (MIBs) have the potential to replace lithium-ion batteries (LIBs) because of low cost, high capacity, and safety. Herein, we perform first-principles calculations to investigate the feasibility of BGe monolayer as an electrode material for MIBs. The low diffusion barriers (0.14 ∼ 0.76 eV) of Mg give rise to the high-rate performance. More importantly, BGe exhibits a remarkable theoretical capacity of 3856 mA h⋅g−1 and a relatively low open-circuit voltage of 0.264 V. The slight volume expansion (5.63%) for fully magnesiated BGe is beneficial to maintain the electrode stability during cycling. Finally, the solvent effects are considered, and the solvent with a high dielectric constant is beneficial to the migration of Mg, contributing to a high charging rate. The above-mentioned intriguing theoretical findings suggest the BGe monolayer could be an efficient anode material for MIBs.