Electrochemical Method of Producing Graphene-Based Supercapacitor Electrode from Coke or Coal

A method of 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 method comprising:

• (a) forming an intercalated coke or coal compound by an electrochemical intercalation procedure which is conducted in an intercalation reactor, wherein said reactor contains (i) a liquid solution electrolyte comprising an intercalating agent;
• (ii) a working electrode that contains said coke or coal powder as an active material in ionic contact with said liquid solution electrolyte, 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;
• and (iii) a counter electrode in ionic contact with said liquid solution electrolyte, and wherein a current is imposed upon said working electrode and said counter electrode at a current density for a duration of time sufficient for effecting electrochemical intercalation of said intercalating agent into said interlayer spacing;
• (b) exfoliating and separating said hexagonal carbon atomic interlayers from said intercalated coke or coal compound using an ultrasonication, thermal shock exposure, mechanical shearing treatment, or a combination thereof to produce isolated graphene sheets, which are dispersed in a liquid medium to form a graphene suspension;
• and
• (c) shaping or shaping and drying said graphene suspension into said supercapacitor electrode that is porous and has a specific surface area greater than 200 m2/g.