High-capacity silicon-based anode material for lithium ion battery and preparation method thereof, and lithium ion battery

The invention discloses a high-capacity silicon-based anode material for a lithium ion battery and a preparation method thereof, and the lithium ion battery. The material comprises nanometer silicon, graphite, organic matter pyrolytic carbon and lithium fluoride. A preparation method comprises the following steps of carrying out mixing, drying and vacuum baking on the nanometer silicon, the graphite and a pyrolytic carbon organic matter precursor to obtain a composite precursor, baking the composite precursor to obtain a pyrolytic carbon coated composite, and utilizing lithium salt solution and fluoride solution to carry out in-situ reaction on the surface of the composite to generate a lithium fluoride coating layer, namely the high-capacity silicon-based anode material for the lithium ion battery. Through in-situ generation of the lithium fluoride on the surface of the silicon-based composite, the interface characteristic of the material is effectively improved, the compactness and the stability of a solid electrolyte membrane formed by the material in the first lithium insertion process is improved, so that the electrochemical performance of the material is improved, the first charge and discharge efficiency of the battery is more than 80%, and the capacity retention ratio after 50 charge and discharge cycles is more than 85%.