Preparation method of silicon/graphene nanocomposite material for cathode of lithium ion battery

The invention relates to a preparation method of a silicon/graphene nanocomposite material for a cathode of a lithium ion battery, which comprises the steps of: preparing oxidized graphite; preparing a silica/ graphene nanocomposite material under the existence of a surfactant; then preparing the silicon/graphene nanocomposite material for the cathode of the lithium ion battery through the magnesiothermic reduction reaction. Compared with the prior art, the graphene in the composite material, prepared by the invention, can better inhibit volumetric expansion of silicon material in the insertion and separation process of lithium ions so as to improve the circulating performance of the composite material greatly, so that the volume of the material after 30 circulations under the current of 200mA/g is still maintained to be above 1100mAh/g.