Silicon Nanoparticles in Graphene Sponge for Long-Cycling-Life and High-Capacity Anode of Lithium Ion Battery

A microwave plasma enhanced chemical vapor deposition (MPECVD) method is used to synthesize nanocarbon structures on silicon particles. The structure is analyzed by scanning electron microscope (SEM), Raman spectroscopy and X-ray diffractometer (XRD). The results show that silicon particles are surrounded by wall-like nanographite and multilayer graphene, also known as graphene nanowalls (GNWs). The nanocarbon structures provide excellent chemical and electrochemical properties and good electrical conductivity enabling much improved performance of lithium ion batteries (LIBs) anode made of nanocarbon coated silicon particles. LIBs maintain the high capacity of 2000 mAh/g for 100 cycles of charging and discharging exhibiting very little decrease in capacity. Graphene nanowalls provide multiple conductive paths for silicon particles to remain being electrically connected to the external circuits allowing lithium ions and electrons to enter and leave silicon particles for charging and discharging.