Silicon-carbon negative electrode material, preparation method thereof and lithium ion battery

The invention discloses a preparation method of a silicon-carbon negative electrode material, which comprises the following steps: (1) in an inert atmosphere, introducing a mixed gas comprising a silicon source gas A and a nitrogen source gas into a reactor with a built-in porous carbon substrate, and carrying out vapor deposition to obtain a porous carbon substrate coated with a silicon nitride layer; in the mixed gas, the flow ratio of the silicon source gas A to the nitrogen source gas is (1-4): 1; (2) introducing a silicon source gas B into the reactor, and carrying out secondary vapor deposition to obtain a silicon-carbon composite material; and (3) introducing a carbon source gas into the reactor, and carrying out high-temperature carbon coating and post-treatment to obtain the silicon-carbon negative electrode material. The lithium ion battery assembled by the silicon-carbon negative electrode material prepared by the method disclosed by the invention has excellent cycling stability, high reversible sp