Oral SiO2/3D porous carbon composite as a superior anode material for lithium ion butteries
Silica (SiO2) has been considered as one of the most promising materials for anode of lithium ion batteries (LIBs) owing toits low discharge potentials and high theoretical specific capacity. Furthermore, SiO2 is a resource abundant, low cost andenvironmental friendly material. However, the practical use of SiO2 nanostructure is hindered by its intrinsic poor electricconductivity and large volume changes during repeated charge-discharge processes. To overcome these drawbacks, wefabricated a SiO2/3D porous carbon nanocomposite by a facile and environmentally friendly synthesis route. The structural andelectrochemical characteristics of the composite anode material have been investigated by X-ray diffraction (XRD), scanningelectron microscope (SEM), transmission electron microscope (TEM), and electrochemical measurements. It is found thatcarbon matrix with three dimensional porous structure is favorable for the short transport of both electrons and Li ions, leadingto good conductivity and fast charge/discharge rates. Moreover, the porous structure of the matrix could efficiently alleviatethe volume expansion of SiO2 during Li intercalation. As a result, the SiO2/porous carbon nanocomposite demonstrated a highreversible capacity of 498.8 mAhg-1, good cycling performance (a specific capacity of 434 mAhg-1 after the 50th cycle at a currentdensity of 100 mAg-1) and high rate capability (187.4 mAhg-1 even at 5 Ag-1).