First-principles study on sodium storage properties of beryllium and boron dual-doped graphyne

First-principles calculations were performed to study the electronic structure, sodium adsorption behavior and storage performance of γ-graphyne (GY) and beryllium and boron dual-doped γ-graphyne (Be-B DDG) and their potential applications as an anode for sodium ion batteries (SIBs). Results show that the maximum sodium storage capacity of GY in the ground state is ~372 mA h g⁻¹. According to calculation of diffusion energy barrier, beryllium and boron atoms in the Be-B DDG structure can provide quite low energy diffusion paths for sodium ions. After Be and B dual-doping modification, Be-B DDG exhibits a theoretical storage capacity of ~702 mA h g⁻¹ and corresponding average open circuit voltage of 0.108 V. Furthermore, the integration of the Be and B atoms causes a metallic characteristic of the Be-B DDG with a higher electronic conductivity, which is essential requirement for anode materials. Therefore, the excellent electronic properties and sodium storage capacity make Be-B DDG a promising anode material for sodium ion batteries.