New anode material based on SiO-Sn_xCo_yC_z for lithium batteries

A new family of composite materials as anode for lithium-ion batteries, MO-Sn_xCo_yC_z (x:y:z molar ratio), was synthesized by custom-made ultrahigh energy ball milling (UHEM) and conventional SPEX ball milling methods. In the past, alloys such as SnCoC and metal oxides such as SiO, SnO₂, MoO₃, etc., have been studied extensively because of their long cycle life and/or high capacity. The composite metal oxide-SnCoC combines both of these advantages. In this work, we took 50 wt % SiO-50 wt % Sn₃₀Co₃₀C₄₀ as an example, and found that ultrahigh energy ball mill offers more nanoparticles and higher capacity compared with conventional milling. High-energy X-ray diffraction indicates the presence of CoSn₂ and Co Bragg phases and highly distorted phases in the mixture. Extended X-ray absorption fine structure analysis reveals a tremendous difference between UHEM and SPEX samples. The pair distribution function shows the local structure and indicates that SiO and SnCoC are not only a physical mixture, but have reacted chemically. Full-cell testing established the feasibility of the composite as an anode material for high-energy, long-life Li-ion batteries. These results demonstrate that the nanostructured SiO-Sn₃₀Co₃₀C₄₀ composite is a promising anode material for practical applications.