Negative active material and preparation method thereof

The invention discloses a negative electrode active material and a preparation method thereof. The negative electrode active material comprises silicon-containing active substance particles and a polymer layer coating the silicon-containing active substance particles, and a metal compound is dispersed in the polymer layer. The preparation method of the negative electrode active material comprisesthe following steps: (1) preparing required raw materials, and dissolving a polymer monomer in a solvent to form a solution; (2) dispersing a metal compound into the solution to form a mixed solution;(3) dispersing the mixed solution on the surfaces of the active substance particles to obtain the negative electrode active material. According to the invention, a lithium ion channel on the surfaceof the negative electrode active material can be improved, the generation of lithium dendrites and byproducts is inhibited, and the electrical properties, stability and safety of the battery are improved; the preparation method