Tailoring Morphology of Ash-Free Porous Carbon Derived from the Coal-Based Medium Component for High-Performance Supercapacitors

The development of high-performance supercapacitors is critically dependent on the rational design of porous carbon. However, the construction of novel materials with unconventional structures and tailored morphologies remains a formidable challenge. This work employed a facile strategy utilizing the extracted coal-based medium component as precursors to synthesize ash-free hierarchical porous carbon. A precarbonization process was introduced in the conventional KOH activation pathway, and the morphology of porous carbon transformed from circular nested to elongated fissure structures, which greatly affected their electrochemical performance. This structural transition is primarily attributed to the effect of precarbonization on the fluidity of the precursors, thereby influencing the etching pattern of KOH. The obtained fissure-type porous carbon CAC-550 features a hierarchical pore structure, the highest degree of disorder, and a specific surface area of 2958.55 m2 g–1. Notably, the assembled symmetrical supercapacitor exhibits a specific capacitance of 301.79 F g–1 at 0.5 A g–1 along with high energy-power density and demonstrates a prolonged cycle lifespan with 98.41% capacitance retention after 10,000 cycles at 10 A g–1. This work elucidates the mechanistic influence of activation pathways on porous carbon morphology while presenting a methodology for converting bituminous coal into ash-free porous carbon, establishing a viable strategy for the application of coal in high-performance supercapacitors.