First-principles study of dual-doped graphene: towards promising anode materials for Li/Na-ion batteries

Abstract

Two-dimensional materials as electrodes have significant potential in energy storage and conversion and can address the issues related to battery technologies. Accordingly, first-principles calculations were executed to search for the best possible anode material for Li/Na ion batteries. Three families of dual-doped graphene (DDG) including Be–B, BeN, and BeO were studied because it is easier to synthesize DDG instead of its mono-doped counterpart. Among them, Be–B DDG was found to be the most promising since it can cause a massive increase in the adsorption of Li (2.33 eV, by 3.1 times) and Na (2.24 eV, by 4.3 times) at the vdW-DF/DZP level of theory. The integration of these ions caused the structures to become metallic, resulting in good electronic conductivity, which is essential for anode materials. Furthermore, Be–B DDG exhibited an average open circuit voltage of 2.34 V (1.3* V) and 1.82 V (1.02* V) for Li and Na, respectively, when the energy of the isolated gas-phase (* represents the energy of one atom taken from the bulk) is used for Li and Na. This modest average open circuit voltage of 1.3* V for Li is in the range of that of the most commonly used graphite-Li (0.11 V) and TiO₂-Li (1.5–1.8 V). Moreover, the negligible percentage change in the plane of Be–B DDG during the intercalation of Li/Na ensured good cyclic stability. Additionally, the exceptional storage capacities of 2334 mA h g⁻¹ for Li and 1012 mA h g⁻¹ for Na with an open circuit voltage of 0.23* V and 0.25* V, respectively, shows that Be–B DDG has potential as a remarkable anode material for LIBs and SIBs.