First-principles calculations of an asymmetric MoO2/graphene nanocomposite as the anode material for lithium-ion batteries

Abstract

Previous work on the synthesis and preparation of MoO₂/graphene nanocomposites (MoO₂/G) indicates that MoO₂/G is a good anode material for lithium-ion batteries (LIBS). In this work, we used larger super-cells than those used previously to theoretically construct an asymmetric MoO₂/G nanocomposite with smaller lattice mismatch. We then calculated the structural, electronic and Li atom diffusion properties of MoO₂/G using first-principles calculations based on density functional theory. The results show that asymmetric MoO₂/G has metallic properties, good stability and a low Li atom diffusion barrier because of the charge transfer induced by van der Waals interactions. The Li diffusion barriers in the interlayer of MoO₂/G are in the range of 0.02–0.29 eV, depending on the relative positions of the Li atom and the MoO₂ and the C atoms in the graphene layer. The Li diffusion barriers on the outside layers of the MoO₂/G nanocomposite are smaller than those of its pristine materials (MoO₂ and graphene). These results are consistent with experimental results. The adsorption of Li atoms in the interlayer of the nanocomposite further promotes the adsorption of Li atoms on the outside sites of the MoO₂ layer. Hence, the specific capacity of the MoO₂/G nanocomposite is larger than 1682 mA h g⁻¹. These properties all indicate that MoO₂/G is a good anode material for LIBS.