Electrochemical properties of porous carbon derived from coal gasification fine ash via low-temperature alkaline fusion and KOH activation

Coal gasification fine ash (a carbon-based solid waste, CGFA) is regarded as the ideal precursors for constructing carbon-based porous materials due to their low cost, high yield, high carbon content, and abundant pore structure. This study employed CGFA as the raw material and prepared porous carbon samples with a high specific surface area (SBET) of 2167.5 m2/g and a high mesoporous ratio of 80.1 % (by volume) using an low-temperature alkaline fusion-KOH activation method. The sample exhibited ideal double-layer capacitance behavior with a mass-specific capacitance of 219.7 F/g (at 1 A/g) and a capacitance retention rate of 82.6 % (at 1 A/g–20 A/g). The energy density of the assembled symmetrical supercapacitor was 13.4 Wh/kg (corresponding to a power density of 475 W/kg), and the capacitance retention rate was 97.9 % after 15,000 cycles. In summary, this work prepared high-performance porous carbon for supercapacitors from widely existing industrial waste CGFA, which provides a feasible strategy for the application of CGFA derived porous carbon in energy storage materials.