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

Searching for efficient electrode materials with high power density, fast charge/discharge rate, and high conductivity is one of the key challenges in the development of metal ion batteries. Herein, by means of first-principles computations, we demonstrated that the two-dimensional Nb2S2C monolayer is a promising anode material for metal ion batteries. The Nb2S2C monolayer has rather good kinetic and thermodynamic stability, and it is metallic with considerable electronic states at the Fermi level. The production of the Nb2S2C monolayer from its experimentally known bulk phase via exfoliation strategies should be rather feasible because of the small cleavage energy of 0.38 J/m(2). All the studied metal atoms, including Li, Na, K, and Mg, can be effectively adsorbed on the surface of the Nb2S2C monolayer with pronounced charge transfer. Especially, the diffusion of Li, Na, and K atoms on the Nb2S2C monolayer is rather feasible with a diffusion barrier of 0.23, 0.11, and 0.07 eV, respectively, whereas Mg has a relatively high diffusion barrier of 0.47 eV. Remarkably, the efficient accommodation of metal atoms on both sides of the Nb2S2C monolayer results in a high theoretical capacity of 194.36, 348.20, 157.60, and 690.52 mA h/g and an open circuit voltage of 0.92, 0.31, 0.26, and 0.18 V for Li, Na, K, and Mg storage, respectively. These results suggest that the Nb2S2C monolayer can be utilized as a promising anode material for metal ion batteries with high power density and good rate capacity.