Investigations on V₂C and V₂CX₂ (X = F, OH) Monolayer as a Promising Anode Material for Li Ion Batteries from First-Principles Calculations

First-principles calculations are performed to study the electronic properties and Li storage capability of V 2 C and its corresponding fluoride and hydroxide. We find that the V 2 C monolayer is metallic with antiferromagnetic configuration, while its derived V 2 CF 2 and V 2 C(OH) 2 in their the most stable configurations are small-gap antiferromagnetic semiconductors. Li adsorption could enhance the electric conductivity of V 2 C fluoride and hydroxide. The bare V 2 C monolayer shows fast Li diffusion with low diffusion barrier height and very high Li storage capacity (with theoretical value ∼940 mAh/g), while the passivated F or OH atoms on its surface tend to impede Li diffusion and largely reduce the Li storage capacity. Moreover, the average intercalation potentials for V 2 C-based materials are calculated to be relatively low. Our results suggest that V 2 C monolayer could be a promising anode material for Li-ion batteries.