Method for preparing lithium battery silicon-carbon composite film negative electrode

The invention relates to the field of silicon-carbon composite films, in particular to a method for preparing a silicon-carbon composite film with good cycle performance. A method for preparing a lithium battery silicon-carbon composite film negative electrode includes the following steps: using a thermoplastic organic film as a raw material, stretching the film in a rolling device successively bythree groups of rollers with a rotation speed ratio of 1: 1.05 to 1.15: 1.15 to 1.25, and simultaneously spraying ethyl orthosilicate, sodium bicarbonate and ammonia water onto the rollers to form asilica layer; drying the film, then uniformly spraying a small amount of magnesium powder onto the surface of the film, and folding and cutting the film into 3 to 5 layers; carbonizing the film at a high temperature: keeping constant temperature for 28-36 minutes at 195-210 degrees centigrade, raising the temperature to 690-720 degrees centigrade and then keeping constant temperature for 1.9-2.5 hours, and then raising the