▎ 摘　　要

Up to now, the cost-effective mass production of pristine graphene sheets remains a significant challenge. We report a binary solvent system of dimethylformamide and n-butylalcohol that facilitates the high concentration production of unoxidized graphene through liquid-exfoliation assisted with sonication. A stable dispersion with concentration as high as 6.5 mg/ml, was received via this method. The conductivity of a film made from the graphene sheets had a conductivity of 27,000 S/m. The supercapacitor fabricated by graphene exhibits a giant capacitance of 600 F/g and an outstanding long-term stability. (C) 2015 Elsevier Ltd. All rights reserved.