Superior Performance of Electrochemical Double Layer Supercapacitor Made with Asphaltene Derived Activated Carbon Fibers

High energy and power values are obtained from fabricated electrochemical double layer supercapacitor (EDLS) cells derived from asphaltene precursors, which are a solid by‐product of bitumen extraction in pentane solvents. Chemical activation, using dry KOH, is used to activate carbon fibers. Chemical activation introduces high specific surface areas (SSAs) into the fiber microstructure by partially etching the carbon. The electrodes are prepared by mixing activated fibers, polytetrafluoroethylene (PTFE), and acetylene black to form flexible electrode films. The unique bimodal pore size distribution with large micropore and mesopore volumes (micropore volume as high as 0.88 cm 3 g −1 ), from chemical activation, generate high‐performance EDLS symmetric cells with capacitance values exceeding 310 F g −1 in aqueous electrolytes and 210 F g −1 in ionic liquid electrolytes (at a specific current of 40 mA g −1 ). A specific energy of 36 Wh kg −1 at a specific power of 525 W kg −1 is reached in ionic liquid electrolytes.