Controlled fabrication of Si nanoparticles on graphene sheets for Li-ion batteries

A new route is presented for the synthesis of Si nanoparticle/Graphene (Si–Gr) composite by a sonochemical method and then magnesiothermic reduction process. During the process, silica particles were firstly synthesized and deposited on the surface of graphene oxide (SiO2–GO) by ultrasonic waves, subsequent low-temperature magnesiothermic reduction transformed SiO2 to Si nanoparticles in situ on graphene sheets. The phase of the obtained materials was influenced by the weight ratio of Mg to SiO2–GO. With the optimized ratio of 1 : 1, we can get Si nanoparticles on Gr sheets, with the average particle size of Si around 30 nm. Accordingly, the resultant Si–Gr with 78 wt% Si inside delivered a reversible capacity of 1100 mA h g−1, with very little fading when the charge rates change from 100 mA g−1 to 2000 mA g−1 and then back to 100 mA g−1. Thus, this strategy offers an efficient method for the controlled synthesis of Si nanoparticles on Gr sheets with a high rate performance, attributing to combination of the nanosized Si particles and the graphene.