Preparation of Sn-Cu/Graphene Nanocomposite for High-Performance Lithium-Ion Batteries

Sn-Cu-graphene composites have been synthesized through a facile one pot co-precipitation method. The Graphene and copper could provide additional mechanical strength to prevent the crack and pulverization of the electrode structure during repeated volume expansion and contraction, which helps to maintain the integrity of the Sn electrodes and the electrically conductive network, and eventually leads to better cycling performance. Graphene can enhance mechanical properties, prevent the aggregation between Sn-Cu nanoparticles, and provide enough void space to buffer volume change of Sn-Cu. The surface morphology of the produced core-shell Sn-Cu/Graphene composite powders was characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS) and Raman spectroscopy X-ray diffraction (XRD) analysis was performed to investigate the structure of the Sn-Cu/Graphene composite powders. The lithium storage capability of the composites electrode is evaluated by cyclic voltammetry and galvanostatic charge-discharge tests. The resistivities of the produced Sn-Cu/Graphene composite electrodes were studied using electrochemical impedance spectroscopy (EIS).  The results show that the Sn-Cu composites embedded in graphene exhibit superior lithium storage performance compared to pure Sn, Sn-Cu, Sn-Graphene, Graphene composites due to the buffering effects of Cu and the excellent confinement and conductivity of graphene.