Supercritical Fluid Production of Graphene-Based Supercapacitor Electrode from Coke or Coal

A process for producing a graphene-based supercapacitor electrode from a supply of coke or coal powder containing therein domains of hexagonal carbon atoms and/or hexagonal carbon atomic interlayers with an interlayer spacing, said process comprising:

• (a) exposing said supply of coke or coal powder to a supercritical fluid at a first temperature and a first pressure for a first period of time in a pressure vessel to enable penetration of the supercritical fluid into an internal structure of the coke or coal;
• wherein said coke or coal powder is selected from the group consisting of petroleum coke, coal-derived coke, meso-phase coke, synthetic coke, leonardite, anthracite, lignite coal, bituminous coal, natural coal mineral powder, and a combination thereof;
• (b) rapidly depressurizing said supercritical fluid at a fluid release rate sufficient for effecting exfoliation and separation of said coke or coal powder to produce isolated graphene sheets, which are dispersed in a liquid medium to produce a graphene suspension;
• and
• (c) shaping and drying said graphene suspension to form said supercapacitor electrode that is porous and has a specific surface area greater than 200 m2/g.