The role of graphene in SnS2@Graphene for rechargeable lithium batteries: A view from the electronic structure

Based on the first-principles study, the adsorption and electron transfer properties of Li atom at different sites of SnS2 monolayer, SnS2@Graphene 2D-nanocomposite are analyzed. The differential charge density and density of states (DOS) analysis show that the graphene substrate as an electron donor can change the 2D-nanocomposite from a semiconductor to a metal, and reduce the adsorption energy of Li atom by decreasing the charge transferring from Li atom to SnS2. This indicates that graphene substrate is beneficial for improving the performance of SnS2@Graphene. Meanwhile, the Li atoms tend not to cluster on the SnS2@Graphene 2D-nanocomposite, which is useful to prolong the lifespan of the SnS2@Graphene. The functionality of graphene in SnS2@Graphene 2D-nanocomposite is proved by other electron donor substrates, such as a two-H-atom model and a Sn (111) substrate model. All the results indicate that the graphene, as an electron donor in SnS2@Graphene 2D-nanocomposite, plays a key role in improving the performance of SnS2 in rechargeable lithium batteries.