Preparation method of multi-stage structured silicon-carbon composite negative electrode material of lithium ion battery

The invention discloses a preparation method of a multi-stage structured silicon-carbon composite negative electrode material of a lithium ion battery. The preparation method comprises the following steps of (1) preparing an initial sample; and (2) stirring and mixing the sample obtained in the step (1) with graphene in 100mL of tetrachlorosilane solution for 1 hour, performing suction filtration on the obtained sample, putting the sample into a porcelain boat, heating the porcelain boat to 650 DEG C at the rate of 1.5 DEG C per minute under the protection of mixed gas consisting of hydrogen and argon according to a volume ratio of 1 to 4, performing carbonized sintering under the temperature of 650 DEG C for 6 hours, then naturally cooling the sample to room temperature, mixing the obtained sample with elemental sulfur and acetylene black, transferring the mixed sample into a muffle furnace and sintering in air under the temperature of 300 DEG C for 2 hours, thereby obtaining the multi-stage structured silicon-carbon composite negative electrode material. The negative electrode material prepared by the preparation method disclosed by the invention is of a multi-stage composite structure, the particle size distribution is uniform, and the electronic conductivity is high; the silicon-based negative electrode material with the multi-stage structure is excellent in electrochemical performance.