Graphite microspheres decorated with Si particles derived from waste solid of organosilane industry as high capacity anodes for Li-ion batteries

We report the decoration of commercial graphite microspheres (GMs) with Si particles as anode materials for Li-ion batteries. The Si particles are obtained from solid Si waste of organosilane industry that is acid-washed to remove the impurities and further ground. The GMs with a size of 5–40 μm as main active material, Si particles with a size of 1–10 μm as an additive, and sucrose dissolved in water as a binder are mixed and followed by carbonization to obtain Si/C composites containing graphite, Si, and amorphous carbon generated from sucrose. It is found that the composite containing 60.5 wt% of GMs, 22.1 wt% of Si, and 17.4 wt% of amorphous carbon obtained at 800 °C for 5 h shows the best electrochemical performance with a specific capacity of 522.6 mA h g−1 at the current density of 50 mA g−1 and 306.9 mA h g−1 at 500 mA g−1, much higher than those of GMs. Its capacity retention at 500 mA g−1 attains 93.9% after 20 cycles. The work demonstrates the possibility for utilization of the industrial Si waste to enhance graphite anode materials in Li-ion batteries.