Two-dimensional metallic pentadiamond as anode material for Li-/Na-/K-ion batteries with high performance

Abstract Metallic materials composed of light and rich abundant element such as carbon is of current interest in battery technology. In this study, as per the features of 3D pentadiamond reported recently, we propose a two-dimensional (2D) pentadiamond monolayer C558 composed of pentagons and octagons. Based on first-principles calculations, we show that the metallic C558 is dynamically and thermally stable. Furthermore, different from the semiconducting 3D-pentadiamond, the 2D-pentadiamond monolayer C558 shows intrinsic metallicity with several adsorption sites for Li, Na, and K ions, which enable it to exhibit superhigh theoretical capacity of 2727.51, 2231.49, and 743.86 mAh/g, low voltage of 0.33, 0.33, and 0.80 V, and low energy barriers 0.42, 0.25, and 0.10 eV, respectively. The intrinsic metallicity together with ultrahigh specific capacity and low migration barrier suggests that the novel C558 monolayer is promising for Li-, Na-, and K-ion batteries with high performance.