Sustainable utilization method of using coal gasification fine ash to prepare activated carbon for supercapacitor

To solve the problems of resource waste and environmental pollution from coal gasification fine ash (CGFA), it is necessary to develop a high-value and sustainable utilization technology. In this study, a sustainable utilization method for CGFA to prepare activated carbon supercapacitor (AC-SC) was proposed for the first time. AC-SC with a high specific surface area was successfully fabricated via a facile deashing pretreatment and subsequent KOH activation. Results showed that with increasing KOH dosage, the specific surface area of AC-SC samples, “C–O or O[dbnd]C–O” functional groups content, and disorder in carbon skeleton increased. Among them, the AC-SC sample (D-800-1-5) with a carbon source to KOH mass ratio of 1:5, activation temperature of 800 °C, and activation time of 1 h showed an ideal micropore-mesoporous composite type pore structure. Moreover, the BET surface area of the sample was 2224.62 m² g⁻¹. The specific capacitance of the D-800-1-5 sample was 124.06 F g⁻¹ @ 0.5 A g⁻¹, and the capacitance retention rate was as high as 128.7% after 10,000 charge-discharge cycles. These results revealed that D-800-1-5 exhibited excellent capacitance characteristics and rate performance, and proved the feasibility of CGFA as a carbon source for the preparation of AC-SC. The proposed method provided a new technical route for the high value and sustainable utilization of CGFA.