▎ 摘　　要

NOVELTY - Polyimide composite film comprises a polyimide matrix, and a three-dimensional conductive network dispersed in the polyimide matrix, where the components constituting the three-dimensional conductive network comprises three-dimensional graphene comprising carbon nanoparticles as a substrate and graphene sheets grown vertically on the surface of the carbon nanoparticles. USE - The polyimide composite film is useful for preparing electromagnetic shielding elements and/or conductive elements (claimed), and used for communication, medical treatment and flexible electronic devices. ADVANTAGE - The composite film has excellent electrical conductivity, electromagnetic shielding performance, heat resistance and flame retardant performance, and is flexible. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for a method for preparing the composite film, involving dispersing the above-mentioned components in a polyimide solution to obtain composite slurry, coating the composite slurry, and imidizing to prepare the composite film.