Porous Carbon was Prepared by Synergistic Activation of KOH and NiCl2 and Hydrothermal Doping of Thiourea for Supercapacitors

Abstract

The preparation of high-performance carbon-based materials has attracted extensive attention from researchers and achieved significant progress; however, the utilization of low-cost solid waste for fabricating high-performance materials still faces many challenges. In this study, coal pitch, a hazardous industrial byproduct, was used as a carbon source. A tandem strategy involving NiCl2/KOH synergistic activation and thiourea-assisted hydrothermal doping was employed to prepare a porous carbon material, denoted as PC@Ni-NS-2. Through process optimization, a pore structure dominated by 2.53 nm channels (Vap) was successfully constructed. At a current density of 0.5 A/g, the specific capacitance of PC@Ni-NS-2 reached 424.2 F/g, which was higher than those of PC@Ni-0.5 (366.5 F/g) and PC-NS-2 (307.5 F/g). At a power density of 0.5 kW/kg, the energy density of PC@Ni-NS-2 was 47.73 Wh/kg, outperforming PC@Ni-0.5 (46.67 Wh/kg) and PC-NS-2 (27.78 Wh/kg). In cycling stability tests, the material maintained 95.28% capacitance retention after 10,000 cycles at 7 A/g, with a Coulombic efficiency of 103.77%. The excellent electrochemical performance can be attributed to the high specific surface area (2493.41 m2/g), a rational pore structure, and enhanced pseudocapacitance contribution resulting from Ni2+ and N/S codoping. This study not only provides a new approach for the preparation of high-performance carbon materials but also offers valuable insights into the high-value resource utilization of coal pitch.