Pore Structure Regulation and Enhanced Capacitive Performance of Nitrogen Doped Activated Carbon Component of Coal Gasification Fine Slag

ABSTRACT Coal gasification fine slag (CGFS), a refractory solid waste rich in carbon residues, holds potential for high‐value utilization. Here, activated carbon (AC) was prepared via deashing–KOH activation, followed by melamine‐assisted gas‐phase nitrogen doping. The doping tailored electronic structure, introduced pseudocapacitive sites, improved wettability, and optimized pore architecture, significantly boosting electrochemical performance. The optimized sample (CGFS‐AC‐N‐10%) exhibited a surface area of 1692.73 m 2 /g, pore volume of 0.63 cm 3 /g, and superior nitrogen incorporation. At 1 A/g, it achieved 314.8 F/g specific capacitance, 38.9% higher than undoped AC. In a two‐electrode system, the symmetric supercapacitor reached 209.7 F/g and 18.58 Wh/kg at 320.04 W/kg, showing a 33.3% improvement. This work demonstrates a simple strategy to enhance the value of CGFS through nitrogen doping and pore regulation, offering a sustainable pathway for advanced energy storage materials.