NiCl2 molten salt impregnation-activation of porous carbon based on coal tar pitch for supercapacitors

Enhancing the performance of carbon materials remains a significant research challenge. This study introduces NiO to improve their pseudocapacitance, thereby enhancing overall performance. Unlike conventional methods that involve post-synthesis impregnation of porous carbon, this study utilizes nickel salts that participate in the activation reaction to in situ generate NiO composite. In this study, porous carbon was synthesized using an impregnation-activation method with NiCl₂ and KOH. In addition to introducing NiO, NiCl₂ also acts as a catalyst during the activation process by promoting intermolecular dehydration to form conjugated structures, thereby better facilitating the formation of the porous carbon structure. Additionally, it served as a template to enrich the pore structure during KOH activation, resulting in a high specific surface area (SSA) of 1881 m²/g and yielding an optimal material designated as PC@Ni-0.5. The material exhibited a specific capacitance of 366.1 F/g at 0.5 A/g and retained 94.16% of its capacitance after 5000 cycles. A button cell assembled using this material delivered an energy density of 45.7 Wh/kg at a power density of 500 W/kg. The incorporation of NiO significantly enhanced the electrochemical performance of the carbon material. This study offers a novel approach for the resource utilization of coal tar pitch and presents an effective method for composite metal oxides into carbon-based materials.