Electrochemical reduction of nano-SiO2 in hard carbon as anode material for lithium ion batteries

A composite of silica (SiO2) and hard carbon was prepared by hydrothermal reaction. Special attention was paid to the characterization of the possible electrochemical reduction of nano-SiO2 in the composite. Evidence by solid-state nuclear magnetic resonance (NMR) and X-ray photoelectron spectroscopy (XPS) and high lithium storage capacity of the composite prove the electrochemical reduction of nano-SiO2 and the formation of Li4SiO4 and Li2O as well as Si in the first-discharge. The reversible lithium storage capacity of the nano-SiO2 is as high as 1675 mAh/g.