▎ 摘　　要

NOVELTY - Preparation of graphene thermal-conductive sheet involves preparing graphene by filling carbon dioxide gas in graphite powder, injecting liquefied carbon dioxide, obtaining a graphite dispersion, crushing, performing high-pressure friction treatment, stripping, subjecting to instantaneous pressure relief, performing gas explosion, collecting gas and obtaining graphene, mixing the product with solid phase nitrogen-containing precursor, sintering, obtaining a nitrogen-doped graphene, mixing with a polymer binder, applying on metal substrate, forming a composite material and drying. USE - Preparation of graphene thermal-conductive sheet (claimed). ADVANTAGE - The method enables economical and easy preparation of graphene thermal-conductive sheet with high yield within short period of time, using organic or inorganic solid nitrogen source. DETAILED DESCRIPTION - Preparation of graphene thermal-conductive sheet involves preparing graphene by filling carbon dioxide gas in graphite powder, such that the system pressure is 10-15 MPa, injecting liquefied carbon dioxide, obtaining a graphite dispersion, rapidly agitating or shearing the obtained graphite dispersion at a rate of 3000-5000 rpm, obtaining a crude product, high-speed crushing the crude product, stripping, performing high-pressure friction treatment and stripping, or performing high-pressure friction treatment of the crude product, stripping, high-speed crushing and stripping to obtain a graphene primary product, repeating the process, subjecting resultant graphene primary product to an instantaneous pressure relief, performing gas explosion, collecting gas and obtaining a final graphene powder product, mixing the resultant product with solid phase nitrogen-containing precursor chosen from nitrogen-containing compounds of formulae: C6H12N4 (I), C6H5COONH4 (II), (NH4)2CO3 (III), HOC(CO2NH4)(CH2CO2NH4)2 (IV), HCO2NH4 (V), C3H3N6 (VI), C11H7N (VII), C10H6(CN)2 (VIII) and C12H7NO2 (IX), sintering the mixture at 500-700 degrees C for 4-7 hours, obtaining a nitrogen-doped graphene, mixing the nitrogen-doped graphene with a polymer binder to form a slurry mixture, applying the slurry mixture on surface(s) of a metal substrate, forming a composite material, placing the composite material in a high-temperature oven and drying to form a heat sink. The weight ratio of graphene and solid phase nitrogen-containing precursor is 1:2-1:10.