The invention discloses a method for preparing a
silicon / carbon
composite material with a magnesiothermic reduction process, and belongs to the technical field of
composite material preparation. The method comprises the following steps: (1) mixing a
silicon dioxide source, an organic
carbon source and a
solvent, carrying out ball-milling to prepare a uniformly pulpous mixture, and obtaining a
silicon dioxide-carbon precursor
composite material through
drying; (2) mixing the
silicon dioxide-carbon precursor composite material with
magnesium powder to carry out a magnesiothermic reduction reaction, collecting products and carrying out acid
pickling and washing, and
drying to obtain the silicon / carbon composite material. According to the method,
silicon dioxide reduction and high temperature
carbonization are completed by using a one-step process, and the method has the advantages of simple technical process, low cost and large-scale production; the prepared composite material effectively maintains the appearance of
porous silicon, so that the composite material has preferable capability for bearing volumetric strain; the
porous composite material is applied to a
lithium battery, so that the
lithium-
ion de-intercalation depth is small, the
ion diffusion path is short, the reversible capacity and coulombic efficiency of the
lithium battery are effectively improved, and the cycle life is prolonged.