Low-cost carbon derived from coal-coke for high-performance supercapacitors

Converting coal-coke into high-value carbon materials is an effective avenue to realize resource high-value utilization. Here, we employ a two-step method to convert coal-coke into capacitive carbon. Coal-coke is first pretreated with mixed acid of hydrochloric acid and nitric acid and then chemically activated by potassium hydroxide at a high temperature. Prepared coal-carbon has a high specific surface area of 1633 m 2 /g and plenty of oxygen and nitrogen dopants, which are beneficial for electric double-layer and Faradic processes, respectively. Coal-carbon exhibits a high specific capacitance of 237 F/g, twice as high as commercial active carbons. Moreover, it delivers a capacitive retention rate of 92 % after running 3000 cycles. This good electrochemical performance suggests that coal-coke-derived porous carbon can replace commercial active carbons as a low-cost candidate for supercapacitors. This work proposes a feasible way to utilize coal-coke with high value and provide low-cost materials to supercapacitors.