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 CuxZn, 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 CuxZn 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.