▎ 摘　　要

NOVELTY - Preparation of graphene involves stirring different sized natural crystalline flake graphite, concentrated sulfuric acid, potassium permanganate and sodium nitrate, adding distilled water, preparing graphite oxide, ultrasonic-treating, preparing graphene oxide dispersion liquid, purifying obtained dispersion liquid, removing aqueous phase, adding distilled water, obtaining graphene oxide, dispersing graphene oxide in distilled water, extracting, purifying, adding hydrazine hydrate, performing reduction-oxidation of graphene dispersion liquid, filtering, centrifuging, and cleaning. USE - Preparation of graphene used for capacitor, fuel battery, sealing material and catalyst carrier. ADVANTAGE - The method enables economical and efficient preparation of high-purity graphene by a simple process in a short period of time. DETAILED DESCRIPTION - Preparation of graphene involves stirring different sized natural crystalline flake graphite as raw material, concentrated sulfuric acid, and potassium permanganate and sodium nitrate as an oxidizing agent for 1-6 hours, adding distilled water for diluting concentrated sulfuric acid, stirring at 50-100 degrees C, preparing graphite oxide, removing excess of potassium permanganate oxidized graphite and its byproduct using hydrogen peroxide and dilute hydrochloric acid, ultrasonic-treating for 30 minutes to 4 hours, preparing graphene oxide dispersion liquid, purifying the graphene oxide dispersion liquid by extraction method using ethyl acetate, toluene or benzene as extracting agent, stirring, standing and layering, removing aqueous phase, then adding distilled water, repeating extraction and separation process for 2-3 times, filtering or centrifuging, removing extraction solvent, obtaining graphene oxide, dispersing graphene oxide in distilled water, extracting, purifying, adding hydrazine hydrate as reducing agent, performing reduction-oxidation of graphene dispersion liquid, filtering, centrifuging, and cleaning.