Study on the synergistic lithium storage performance of Sn/graphene nanocomposites via quantum chemical calculations and experiments

A general strategy is demonstrated to achieve superior lithium storage properties by constructing Sn/graphene nanocomposite architecture. The synergistic lithium storage performance of Sn/graphene is initially investigated by quantum chemical calculations based on density functional theory. Results show that the electronic conductivity of Sn/graphene is superior to that of Sn metal. Subsequently, a facile precipitation method is designed to fabricate Sn/graphene composites. SEM and TEM analysis reveals that Sn nanoparticles (40-80 nm) are homogenously sandwiched between graphene nanosheets. Cyclic voltammetry and galvanostatic charge/discharge measurements show that Sn/graphene composites exhibit superior lithium storage capability as compared to bare Sn. The enhanced performance is further investigated by electrochemical impedance spectroscopy. Results suggest that the addition of graphene in the nanocomposites significantly improves the electron transfer, which is consistent with the quantum chemical calculations.