Metallic Nb₂S₂C Monolayer: A\nPromising Two-Dimensional Anode Material for Metal-Ion Batteries

Abstract

Searching for efficient\nelectrode materials with high power density,\nfast charge/discharge rate, and high conductivity is one of the key\nchallenges in the development of metal ion batteries. Herein, by means\nof first-principles computations, we demonstrated that the two-dimensional\nNb₂S₂C monolayer is a promising anode material\nfor metal ion batteries. The Nb₂S₂C monolayer\nhas rather good kinetic and thermodynamic stability, and it is metallic\nwith considerable electronic states at the Fermi level. The production\nof the Nb₂S₂C monolayer from its experimentally\nknown bulk phase via exfoliation strategies should be rather feasible\nbecause of the small cleavage energy of 0.38 J/m². All\nthe studied metal atoms, including Li, Na, K, and Mg, can be effectively\nadsorbed on the surface of the Nb₂S₂C monolayer\nwith pronounced charge transfer. Especially, the diffusion of Li,\nNa, and K atoms on the Nb₂S₂C monolayer is rather\nfeasible with a diffusion barrier of 0.23, 0.11, and 0.07 eV, respectively,\nwhereas Mg has a relatively high diffusion barrier of 0.47 eV. Remarkably,\nthe efficient accommodation of metal atoms on both sides of the Nb₂CS₂ monolayer results in a high theoretical capacity\nof 194.36, 348.20, 157.60, and 690.52 mA h/g and an open circuit voltage\nof 0.92, 0.31, 0.26, and 0.18 V for Li, Na, K, and Mg storage, respectively.\nThese results suggest that the Nb₂S₂C monolayer\ncan be utilized as a promising anode material for metal ion batteries\nwith high power density and good rate capacity.