▎ 摘　　要

NOVELTY - Preparation of graphene sheet involves subjecting expandable graphite to primary expansion process, ultrasonic dispersing in solution (a1), obtaining a nano-graphene sheet, softening the nano graphene sheet by fuming sulfuric acid and hydrogen peroxide, subjecting to secondary expansion process, ultrasonic dispersing in solution (a2), obtaining pure surface of graphene powder, providing the obtained graphene powder into a mold, adjusting pressing time and pressure of graphene powder, and directly pressing the graphene sheet into different density and different thickness. USE - Preparation of graphene sheet used in electronic packaging applications. ADVANTAGE - The method enables preparation of graphene sheet having thermal conductivity of 100Wm-1K-1 or more. DETAILED DESCRIPTION - Preparation of graphene sheet involves subjecting expandable graphite to primary expansion process in a muffle furnace, ultrasonic dispersing in solution (a1), obtaining a nano-graphene sheet, softening the nano graphene sheet by fuming sulfuric acid and hydrogen peroxide, subjecting to secondary expansion process in muffle furnace, ultrasonic dispersing in solution (a2), obtaining single and/or double layered graphene sheet powder, hot reducing, obtaining pure surface of graphene powder, providing the obtained graphene powder into a mold, adjusting pressing time and pressure of graphene powder, and directly pressing the graphene sheet into different density and different thickness.