Porous silicon-carbon composite material, preparation method thereof and application of porous silicon-carbon composite material in secondary battery

The invention provides a porous silicon-carbon composite material, a preparation method thereof and application of the porous silicon-carbon composite material in a secondary battery. The method comprises the following steps: enabling spherical silicon-based alloy powder to react with etching liquid at room temperature to obtain a spherical porous silicon material; mixing and ball-milling the spherical porous silicon material and the modified carbon source to obtain a precursor; performing heat treatment on the precursor in a protective atmosphere to obtain a porous silicon-carbon composite material; the etchant includes a surfactant and an acid-free reagent. The porous silicon-carbon composite material provided by the invention is spherical, has complete morphology, multiple pores and good cycle performance, has the advantages of large capacity, high tap density, high specific surface area, high lithium ion diffusivity and the like, and can be used for large-scale preparation of an electrode negative electro