Theoretical prediction on tetragonal Be2B monolayer as a well-balanced performance anode for lithium-ion batteries

As one of the most important energy storage systems, lithium-ion batteries (LIBs) attract much attention recently. Materials composed of beryllium or boron, due to the lighter molar weight, offer natural advantages for high energy density anode of LIBs. Here, we propose a two-dimensional tetragonal Be2B (T-Be2B) and investigate the performance as a potential anode for LIBs. Through first-principles calculations, T-Be2B exhibits excellent thermal, dynamic, and mechanical stability. As a semiconductor material with the bandgap of 0.303 eV, T-Be2B shows a strong capability to adsorb Li atoms. Furthermore, T-Be2B monolayer demonstrates a low diffusion barrier of 0.26 eV, a moderate theoretical capacity of 929 mA h g−1, and an average open-circuit voltage of 0.88 V. Additionally, the presence of vacancy defects weakens the adsorption ability and migration behavior of Li on T-Be2B, which should be carefully handled in the experimental preparation process of T-Be2B monolayer. Based on these properties, the T-Be2B monolayer has significant potential as an anode material for LIBs.