▎ 摘　　要

NOVELTY - Preparing graphene/polyimide micro-crystal ball composite material comprises (i) adding high-purity graphene and heat expansion microsphere foaming agent into the soluble polyimide solution, and stirring at high speed to obtain mixed solution of low viscosity, (ii) pouring the mixed solution on the metal plate material and evaporating the solvent to obtain the graphene/polyimide micro-crystal ball composite contact, where the high-purity graphene is prepared by calcining graphite powder at high temperature of 2850 degrees C, inserting layer and mechanical peeling, the carbon content is more than 99.9 wt.%, the thermal expansion microsphere foaming agent is a shell and a core material, the mass ratio of the shell and the core material is 20-30:1, the shell is the copolymer of methyl methacrylate, vinylidene chloride and acrylonitrile and the mass ratio of the methyl methacrylate in the copolymer is 5-25%, vinylidene chloride is 20-75%, and acrylonitrile is 20-70%. USE - The material is useful for solar water heater (claimed). ADVANTAGE - The material has high absorption rate and high conductivity to the heat of the sunlight, and has good application prospect on the solar water heater and photovoltaic power generation. DETAILED DESCRIPTION - Preparing graphene/polyimide micro-crystal ball composite material comprises (i) adding high-purity graphene and heat expansion microsphere foaming agent into the soluble polyimide solution, and stirring at high speed to obtain mixed solution of low viscosity, (ii) pouring the mixed solution on the metal plate material and evaporating the solvent to obtain the graphene/polyimide micro-crystal ball composite contact, where the high-purity graphene is prepared by calcining graphite powder at high temperature of 2850 degrees C, inserting layer and mechanical peeling, the sheet layer is less than 10 layers, the carbon content is more than 99.9 wt.%, the thermal expansion microsphere foaming agent is a shell and a core material, the mass ratio of the shell and the core material is 20-30:1, the shell is the copolymer of methyl methacrylate, vinylidene chloride and acrylonitrile and the mass ratio of the methyl methacrylate in the copolymer is 5-25%, vinylidene chloride is 20-75%, and acrylonitrile is 20-70%, the core material is isopentane, n-pentane, normal hexane, isohexane, isooctane or normal octane, the rotating speed of highspeed stirring is 600-1000 revolutions/minute, the stirring time is 30-90 minutes, the viscosity of the mixed solution is 1.3-10 Pa.s, and the temperature of non-contact heating is 70-200 degrees C. An INDEPENDENT CLAIM is also included for graphene/polyimide micro-crystal ball composite material prepared according to above mentioned method.