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.