Effects of mechanical milling and arc-melting processes on the electrochemical performance of Si-based composite materials

The Si–Ni composite and Si/Ni alloy composite were prepared by high-energy mechanical milling and arc-melting, respectively, in order to investigate the effects of these processes on the electrochemical performance. The microstructures of Si–Ni composite and Si/Ni alloy composite were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). The electrochemical properties have been investigated during 50 cycles for Si–Ni–C composite and Si/Ni alloy–C composite. As a result, both composites demonstrate a higher reversible capacity accompanied with a good cycling stability than the existing Si–C composite. Homogeneously dispersed Ni improved electric conductivity and induced fast charge transport significantly in Si–Ni–C composite whereas the secondary phases (NiSi and NiSi2) played a role of media to accommodate a large volume change of Si during cycling in Si/Ni alloy–C composite. Consequently, it was identified that electrochemical performances of electrode material are affected by structural factors caused by the different processes.