▎ 摘　　要

NOVELTY - 1 pt. wt. Raw material graphite is added to 200 pts. wt. acid solution and stirred, to obtain expanded graphite. The expanded graphite is washed with deionized water and filtered, to obtain wet expanded graphite. The wet expanded graphite is peeled in solution, to obtain graphene dispersion. The peeled graphene dispersion is spray-dried, to obtain graphene powder. Graphene powder is centrifuged/filtered, to obtain slurry graphene or wet solid graphene. The wet solid graphene is easily dispersed in other solvent and dispersant. USE - Preparation of expanded graphite or graphene used for energy storage and thermal management application, optoelectronic device, solar cell, anti-corrosion coating and composite material. ADVANTAGE - The method enables preparation of expanded graphite or graphene with high efficiency and quality and excellent defect resistance at low temperature and pressure by safe and environmentally-friendly method, with low energy consumption. The sp2 hybrid structures of expanded graphite or graphene are not destroyed. DETAILED DESCRIPTION - 1 pt. wt. Raw material graphite is added to 200 pts. wt. acid solution, to obtain suspension. The suspension is stirred at ambient temperature and pressure for 1 minute to 2 hours and maintained still for 48 hours, to obtain expanded graphite. The acid solution comprises sulfuric acid solution containing oxidizing agent. The oxidizing agent comprises ammonium persulfate, potassium persulfate, sodium persulfate and/or hydrogen peroxide. The content of oxidant is 0.1-20 times the weight of graphite. The expanded graphite is washed with deionized water and filtered, to obtain wet expanded graphite. The wet expanded graphite is peeled in solution, to obtain graphene dispersion. The peeled graphene dispersion is spray-dried, to obtain graphene powder. Graphene powder is centrifuged/filtered, to obtain slurry graphene or wet solid graphene. The wet solid graphene is easily dispersed in other solvent and dispersant.