Si/Cu-Zn(ox)/C composite as anode material for Li-ion batteries

The silicon based composite Si/Cu-Zn(ox)/C was prepared by ball milling from Si microparticles , Cu-Zn nanopowder heated at air and carbon black. The composite is formed by Si submicrometer particles, Cu-rich Cu x Zn, CuO , ZnO and C nanoparticles . The two oxides are electrochemically active during the first discharge, improving the nanostructuration of the composite and providing Cu nanoparticles that enhance the electronic conductivity with Cu x Zn and C. The nanostructuration helps to buffer the volume variations due to Li-Si alloying reactions during cycling. The composite is further nanostructured during the first cycles as shown by XRD and electrochemical measurements. The material was tested as anode material for Li-ion batteries, providing a reversible capacity of 800 mAh.g −1 during 100 cycles at current of 300 mA.g −1 and a good rate capability. The reversible capacity is mainly due to Li-Si alloying reactions and is stable after few cycles while the solid electrolyte interphase is stabilized after about ten cycles as shown by electrochemical impedance spectroscopy .