▎ 摘　　要

NOVELTY - Preparation of a graphene heat conducting sheet involves (s1) preparing a graphene oxide dispersion liquid, introducing into an annular hollow stainless steel mold, freeze-drying the mold to obtain graphene oxide powder foam, maintaining the graphene oxide powder foam in an annular shape to be stripped from the inner surface of the mold to obtain an annular continuous graphene oxide film, (s2) spraying graphene oxide quantum dots on the inner edge surface of the annular graphene oxide film, attaching the annular film along an intermediate shaft, flat pressing, placing in a constant humidity box, compacting and molding to obtain flat graphene oxide sheets, (s3) vacuum drying the flat graphene oxide sheets, graphitizing, and cooling to obtain graphene heat-conducting foam, (s4) flat pressing the graphene heat-conducting foam to obtain graphene heat-conducting sheet with compact density of 1.85-2.0 g/m3. USE - Preparation of graphene heat conducting sheet for reinforcing longitudinal heat flux transmission (claimed) used in fifth generation (5G) electronic equipment. ADVANTAGE - The method enables to prepare graphene heat conducting sheet that has high compact density, high heat-conducting performance, and large-flux heat dissipation, and improves graphene sheet temperature drop without annular flat structure by 20-30%. DETAILED DESCRIPTION - Preparation of a graphene heat conducting sheet involves (s1) preparing a graphene oxide dispersion liquid with the concentration of 3-4 wt.%, introducing the dispersion liquid into an annular hollow stainless steel mold, connecting edges of two rings with a positive and negative direct-current power supply, charging the two ring-shaped molds, rearranging functional groups of graphene oxide lamellar under the guidance of charges, uniformly distributing on the surface of an electrode, freezing by using liquid nitrogen in a power-on state until the graphene oxide lamellar functional groups are completely frozen, and locking the distribution state of the graphene oxide, freeze-drying the mold to obtain graphene oxide powder foam, and maintaining the graphene oxide powder foam in an annular shape to be stripped from the inner surface of the mold to obtain an annular continuous graphene oxide film, (s2) spraying graphene oxide quantum dots on the inner edge surface of the annular graphene oxide film, attaching the annular film along an intermediate shaft, flat pressing, placing in a constant humidity box for 12-24 hours, and compacting and molding by using a flat press to obtain flat graphene oxide sheets, (s3) vacuum drying the flat graphene oxide sheets under the protection of argon, graphitizing, and cooling to obtain graphene heat-conducting foam, (s4) flat pressing the graphene heat-conducting foam by using a flat press to obtain graphene heat-conducting sheet with compact density of 1.85-2.0 g/m3.