Energy storage performance of Vn+1Cn monolayer as electrode material studied by first-principles calculations

Abstract

Two-dimensional transition metal carbides are expected to be potential negative electrode materials, due to high conductivity, large cation storage capabilities, and unique mechanical properties. In this work, theoretical analysis of Li atom storage capacity and diffusion behavior of the V_n+1C_n monolayer are investigated. It is predicted that the V₃C₂ and V₄C₃ monolayers can be synthesized through selective etching of Al layers of the corresponding V₃AlC₂ and V₄AlC₃ phases. The V_n+1C_n monolayer is found to be of metallic character with a high total density of states at the Fermi level. Moreover, V_n+1C_n surfaces can be adsorbed by lithium with a low diffusion barrier and high storage capabilities compared with other carbon-based materials. To enhance performance, the surface functionalization should be avoided in the practical synthetic experiments. The above study results provide insight into the energy storage performance of the V_n+1C_n monolayer, and predict that the not yet synthesized V₃C₂ and V₄C₃ monolayers are promising candidates for electrode materials.