Multi-alkali ion storage in a two-dimensional B4C4N2 monolayer: A universal anode material for Li/Na/K-ion batteries

With the growing demand for high-performance electrode materials in electrochemical energy storage devices, two-dimensional (2D) materials have demonstrated significant potential in the field of alkali metal ion batteries due to their unique structural advantages. In this study, first-principles density functional theory calculations were employed to systematically evaluate the application prospects of the novel B 4 C 4 N 2 monolayer as an anode material for Li + , Na + and K + ion batteries. Multidimensional validation, including phonon spectra, binding energies, ab initio molecular dynamics (AIMD) simulations and elastic constants, indicates that B 4 C 4 N 2 possesses excellent intrinsic structural stability, maintaining an intact 2D framework even at high temperatures of 1000 K and under saturated ion loading. Electronic structure analysis reveals its intrinsic metallic nature, with covalent-metallic hybrid bonding ensuring efficient charge transport. In terms of ion storage, B 4 C 4 N 2 exhibits moderate chemical adsorption for Li, Na and K, whilst achieving maximum theoretical specific capacities of 1347.91 and 1123.26 mAh·g −1 . Notably, the minimum diffusion energy barrier for K + on the B 4 C 4 N 2 surface is merely 0.069 eV, demonstrating virtually unimpeded migration kinetics. These results indicate that B 4 C 4 N 2 combines high specific capacity, ultra-fast ion diffusion and a robust structural framework, making it a highly promising universal anode material for multi-alkali metal ion batteries.