Computational insight of ZrS2/graphene heterobilayer as an efficient anode material

Abstract

A density functional theory-based study is carried out to examine the electrochemical performance of ZrS2 and graphene monolayers and ZrS2/graphene heterobilayer for anodic applications in rechargeable Li ion batteries (LIBs). The energetic and dynamic stabilities of the heterobilayer have been confirmed first. The low Li diffusion barrier (0.24 eV), low half-cell voltage (0.7 V) and high Li storage capacity (700 mAh/g) of ZrS2 monolayer makes it a prospective 2D anode material for the LIBs. However, the large energy gap of ZrS2 monolayer may reduce the reversibility, while large structural changes are on high Li load can lead to short cycle life. To handle these issues, the ZrS2 monolayer is capped with graphene. The graphene thus provides mechanical strength and conducting channels to the electron flow. It is well known that graphene is unable to store Li for LIBs applications. However, by making its interface with ZrS2 enables it to store Li ion reversibly. Furthermore, the graphene caping provides mechanical strength to the ZrS2 monolayer to insure long cycle life and high recyclability. Thus, the hybrid of ZrS2 and graphene makes a highly efficient 2D anode material for Li ion batteries.