Preparation of Porous Carbon Derived from Different Coal Species and The Supercapacitor Performance

This study aims to explore pathways for the clean conversion of traditional coal resources into green energy storage materials and to investigate the effects of different coal types as precursors on the structure, morphology, and electrochemical properties of the resulting porous carbon materials. We employed four types of bituminous coal as precursors to prepare porous carbon materials (YM-X) via a one-step KOH activation process, and systematically examined the influence of coal type on the pore structure, elemental composition, microstructure, and capacitive performance of the carbon materials. The results demonstrate that the intrinsic properties of coal precursors play a decisive role in determining the performance of the resulting carbon materials. Among them, the sample (YM-3) derived from coal with relatively low ash and volatile contents and an appropriate fixed carbon ratio exhibites an ultrahigh specific surface area of up to 3237.66 m²·g⁻¹, forming a well-developed hierarchical porous structure and achieving self-doping with N and S heteroatoms. Benefiting from the large surface area, abundant porosity, and low charge transfer resistance, YM-3 delivers excellent supercapacitive performance (448 F·g⁻¹), superior rate capability and outstanding cycling stability. Furthermore, the assembled symmetric supercapacitor (YM-3||YM-3) shows an energy density of 11.5 W·h·kg⁻¹ at a power density of 137.5 W·kg⁻¹, demonstrating the promising energy storage performance. This study not only confirms that rational selection of coal precursors and optimization of activation parameters can significantly enhance the capacitive performance of porous carbon electrodes, but also provides a feasible strategy for the green and high-value utilization of traditional coal resources, thereby promoting the sustainable development of coal-derived energy storage carbon materials.