Preparation of graphene-based active carbons from petroleum asphalt for high-performance supercapacitors without added conducting materials

Graphene-based active carbons (G-ACs) with a high specific surface area and high conductivity are promising electrode materials for high-performance supercapacitors. Typically, however, syntheses of the G-ACs call for expensive raw materials and are cumbersome. Here, the G-ACs are obtained by direct chemical activation of petroleum asphalt. The highest specific surface area of the prepared G-ACs is 3505 m 2 /g and the corresponding conductivity is 32 S/m. Electrodes fabricated using the as-prepared G-ACs, i.e., without any conductive additives, demonstrate high specific capacitance and high rate performance. The specific capacitances of optimized G-ACs, as measured in a 1 mol/L TEABF 4 /AN electrolyte and the neat ionic liquid EMIMBF 4 , are 155 and 176 F/g at 1 A/g, providing the high energy density of 39.2 and 74.9 W h/kg, respectively. In addition, the G-ACs exhibited excellent rate capability with a negligible capacitance decay from 0.5 to 10 A/g in both 1 mol/L TEABF 4 /AN and neat EMIMBF 4 electrolytes. Furthermore, the optimized G-AC has a high energy density (68.5 W h/kg) at a relatively high power density (8501 W/kg), indicating that it holds potential for application in green energy storage.