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.