New Anode Material Based on SiO–SnxCoyCz for Lithium Batteries

Abstract

A new family of composite materials as anode for lithium-ion batteries, MO-SnxCoyCz (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.