First-principles investigation of defective graphene anchored with small silicon clusters as a potential anode material for lithium-ion batteries

The interplay between vacant graphene and silicon (Si) provides a viable way to tune the properties for successful implementation as a promising anode material of lithium-ion batteries. Therefore, understanding the interaction of such defects when coupled with silicon clusters is of particular importance. Using first-principles methods, we investigate the atomic adsorption on graphene with a single vacancy and a double vacancy, as well as the structural and electrical properties. The presence of defects strongly enhances the interaction between the defective graphene and Si clusters, dependent on Si type. We observe that SiO strongly adsorbed on the divacancy graphene with the adsorption energy of -4.49 eV could provide extra intercalation places for Li atoms, augmenting the adsorption energy of Li from -1.18 eV to -4.15 eV compared to the pristine graphene. Moreover, it exhibits a threefold increase in the lithiation /de-lithiation potential and the superior Li storage capacity. The enrichment of Li adsorption and uptake is also observed in the hybrid Si6/single-vacancy graphene. Thus, the interface engineering via deposition of various Si clusters on the vacant graphene could be a new strategy to achieve a promising anode material for Li-ion batteries.