Porous Silicon/Carbon Nanocomposites As Anode Materials for Lithium-Ion Batteries

A series of porous silicon/carbon composites were successfully synthesized by employing mesoporous silica (SBA-15 and MCM-48) and diatomite as silicon precursor, followed by low temperature magnesiothermic reduction, impregnation and carbonization of phenolic resin. The structure and morphology of the porous composites were characterized by X-ray diffraction, Raman spectroscopy, field emission scanning electron microscope and nitrogen absorption and desorption. Electrochemical performance of the porous composite electrodes were investigated. The obtained Si/C composites present an interweaved porous structure composed of Si, inactive SiO_x and conductive carbon. The ordered pore structure is retained after the magnesiothermic reduction of well-ordered mesoporous silica. The resulting porous Si/C composites exhibit high reversible capacity and excellent cycling performance. These improvements could be attributed to the introduction of carbon in the porous Si/C composites, which effectively improve the electrical conductivity. Moreover, the porous structure can accommodate the volume expansion and improve cycling stability of the electrode materials during lithium ion insertion and extraction.