Metallic two-dimensional BP2: a high-performance electrode material for Li- and Na-ion batteries

Abstract

Searching for high-performance electrode materials is an important topic in rechargeable batteries. Using first-principles calculations, we systematically explore the potential application of a two-dimensional BP₂ monolayer as a cathode material for Li-ion and Na-ion batteries. The pristine BP₂ monolayer exhibits metallic characteristics, which facilitate the transportation of electrons. The Li and Na atoms bind strongly to the BP₂ monolayer, indicating a good structural stability. Furthermore, the geometrical structure of BP₂ is well maintained during the adsorption process. The Li and Na ions prefer to move along the zigzag direction with relatively low energy barriers. Especially, the ultralow Na diffusion barrier (0.03 eV) implies that monolayer BP₂ has an excellent charge/discharge capability. The specific capacity and average electrode potential of Li (Na) are 619.45 (279.93) mA h g⁻¹ and 2.89 (2.49) V, respectively. These results reveal that the BP₂ monolayer is an appealing cathode material for alkali-metal batteries.