▎ 摘　　要

NOVELTY - Graphene-based composite filler comprises a graphene powder having a hollow cavity and a functional material filled in the hollow cavity, where the graphene powder has a particle size from 5 nanometer to 300 microns. USE - Graphene-based composite filler. ADVANTAGE - The graphene-based composite filler has high crystalline quality, excellent thermal conductivity and electrical conductivity. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for a method for preparing a graphene-based composite filler, which involves : (A) heating the reaction furnace cavity to a set temperature under a protective atmosphere of a carrier gas; (B) adding a required amount of a transition group metal salt to the constant temperature zone of the reaction furnace cavity as a matrix, and maintaining the temperature for 0-10 minutes; (C) introducing mixed atmosphere of carbon source gas, reducing gas, and carrier gas into the cavity of the reaction furnace, reducing high melting point metal salt in the mixed atmosphere, catalyzing graphite on the surface of the reduced metal salt substrate; (D) taking out the prepared reaction product under a protective atmosphere of a carrier gas to obtain a graphene powder grown on a substrate; (E) using a corresponding acid to etch away the metal substrate to obtain a graphene powder having a hollow cavity structure; and (F) injecting a functional material into the hollow cavity of the obtained graphene powder to obtain graphene-based composite filler.