Polypyrrole coated spherical graphite/SnO2 composite material as well as preparation method and application thereof

The invention belongs to the field of lithium ion batteries, and relates to a polypyrrole coated spherical graphite/SnO2 composite material for a negative electrode of a lithium ion battery as well as a preparation method and application of the polypyrrole coated spherical graphite/SnO2 composite material. The preparation method of the polypyrrole coated spherical graphite/SnO2 composite material comprises the following steps: S1, forming highly dispersed tin dioxide nanoparticles on the surface of oxidized spherical graphite by adopting an in-situ oxidation-reduction reaction to obtain a spherical graphite/SnO2 composite material; s2, a polypyrrole coating layer is formed on the surface of the spherical graphite/SnO2 composite material, hydrochloric acid is doped in the polypyrrole coating layer, and a spherical graphite/SnO2 coated PPy composite material is obtained; and S3, under the protection of inert gas, heating the spherical graphite/SnO2 coated PPy composite material to 550-650 DEG C at a rate of 2-7