Three-Dimensional Porous h-BC₂N Based on BN Chains and Prismane C₈ Units for Alkali Metal Ion Battery Anodes

Here, a new three-dimensional (3D) porous h-BC2N was designed via the assembly of prismane C8 and boron nitride chains as the candidates for alkali metal ion battery anodes. By systematic calculations, it is found that h-BC2N is both thermally and mechanically stable, even at a temperature as high as 1000 K. Li ions can migrate with multiple diffusion directions in h-BC2N, and the minimum diffusion barrier is only 0.10 eV lower than that of graphite. The theoretical specific capacity of the h-BC2N anode for Li is 549 mAh/g, which is higher than that reported for graphite. h-BC2N is also a promising anode for sodium (NIBs) and potassium ion batteries (KIBs) whose specific capacities are also large (549 mAh/g), and the energy barriers are 0.35 and 0.19 eV, respectively. Additionally, LIBs, NIBs, and KIBs exhibit voltage stability upon charging/discharging and good cycling stability. This theoretical exploration may open a new frontier in the search for more practical 3D porous structures as LIBs, NIBs, and KIBs anodes.