Preparation method of high purity and high concentration graphene suspension

The invention relates to a preparation method of a high purity and high concentration graphene suspension, which comprises the following steps of: reacting natural crystalline flake graphite with a strong oxidizer to obtain graphite oxide; spreading the graphite oxide into a dispersing agent, and obtaining a graphene oxide suspension by ultrasonic dispersion; mixing the graphene oxide suspension with hydrazine hydrate under the protection of nitrogen and reacting at constant temperature under ultrasonic radiation to prepare stable graphene suspension. Compared with the traditional method for preparing the graphene suspension, the method introduces ultrasonic in the reduction process of the graphite oxide. The invention has the following advantages that the prepared graphene suspension has high concentration (higher than 1 mg.mL ), high purity (without influence of surface active agents and other impurities), high dispersionstability (time for stable dispersion is more than 60 days) and the like; the graphene prepared by the method has high electrical conductivity (high than 700 S.m ), less number of layers, is simple and easy to implement, and is very suitable for large scale production in industy.