Method for preparing Si/C composite cathode material for lithium ion battery

The invention discloses a method for preparing a Si/C composite cathode material of a lithium ion battery. The method is characterized in that through a liquid phase solidification-high temperature pyrolysis-low temperature treatment combined method, the Si/C composite cathode material having good cycling stability and good rate capability is prepared. Concretely, the method comprises the following steps of uniformly dispersing a silicon source (before or after etching) and graphite in an appropriate solvent in the presence of a second-type additive with control of a temperature to obtain a solid precursor after the solvent is volatilized completely, transferring the solid precursor into a protective atmosphere, carrying out pyrolysis at a high temperature so that the carbon source is pyrolyzed into amorphous carbon and forms a coating layer, carrying out furnace cooling to obtain the Si/C composite cathode material, uniformly mixing the Si/C composite cathode material, a conductive agent and a binder, coating the mixture on a pole piece, carrying out drying, carrying out low-temperature treatment, and carrying out an electrochemical performance test. The method is simple and feasible and has a high practical degree. The Si/C composite cathode material prepared by the method has a high capacity and good cycling stability and a good rate capability after the low-temperature treatment.