Mechanochemical synthesis of Si/Cu3Si-based composite as negative electrode materials for lithium ion battery.

Mechanochemical synthesis of Si/Cu3Si-based composite as negative electrode materials for lithium ion battery is investigated. Results indicate that CuO is decomposed and alloyed with Si forming amorphous Cu-Si solid solution due to high energy impacting during high energy mechanical milling (HEMM). Upon carbonization at 800 °C, heating energy induces Cu3Si to crystallize in nanocrystalline/amorphous Si-rich matrix enhancing composite rigidity and conductivity. In addition, residual carbon formed on outside surface of composite powder as a buff space further alleviates volume change upon lithiation/delithiation. Thus, coin cell made of C-coated Si/Cu3Si-based composite as negative electrode (active materials loading, 2.3 mg cm-2) conducted at 100 mA g-1 performs the initial charge capacity of 1812 mAh g-1 (4.08 mAh cm-2) columbic efficiency of 83.7% and retained charge capacity of 1470 mAh g-1 (3.31 mAh cm-2) at the end of the 100th cycle, opening a promised window as negative electrode materials for lithium ion batteries.