Carbon-coated SiO2 nanoparticles as anode material for lithium ion batteries

A simple approach is proposed to prepare C-SiO2 composites as anode materials for lithium ion batteries. In this novel approach, nano-sized silica is soaked in sucrose solution and then heat treated at 900 °C under nitrogen atmosphere. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) analysis shows that SiO2 is embedded in amorphous carbon matrix. The electrochemical test results indicate that the electrochemical performance of the C-SiO2 composites relates to the SiO2 content of the composite. The C-SiO2 composite with 50.1% SiO2 shows the best reversible lithium storage performance. It delivers an initial discharge capacity of 536 mAh g−1 and good cyclability with the capacity of above 500 mAh g−1 at 50th cycle. Electrochemical impedance spectra (EIS) indicates that the carbon layer coated on SiO2 particles can diminish interfacial impedance, which leads to its good electrochemical performance.