Residual minerals tune coal-derived porous carbon for adsorption and energy storage

Abstract Coal-derived porous carbons are attractive for adsorption and electrochemical energy storage because coal is abundant and suitable for large-scale conversion. However, mineral matter is commonly removed before activation, while the role of residual minerals in directing carbon evolution remains insufficiently understood. Here, Taixi anthracite was subjected to hydrochloric acid, sodium hydroxide, or combined deashing before KOH activation to determine how residual mineral species regulate pore development, carbon microstructure, and oxygen chemistry. Selective deashing generated distinct mineral environments in the precursors and altered the activation pathway, producing porous carbons with different surface areas, pore-size distributions, Raman-derived structures, oxygen-containing groups, thermal behaviors, and transport characteristics. The results revealed an application-dependent trade-off rather than a universal optimum. HCl treatment favored highly developed porosity and superior long-term electrochemical stability, whereas NaOH treatment promoted a micropore-rich structure and higher low-rate capacitance. Combined deashing produced more temperature-stable methylene blue adsorption, while untreated coal-derived carbon showed faster charge transport and ion diffusion. The resulting materials achieved surface areas up to 3101 m 2 /g, specific capacitances up to 179.64 F/g, and capacitance retention of 78.99% after 20,000 cycles. These findings show that deashing is not merely a purification step. Instead, regulating residual mineral species provides a precursor-design strategy for tuning the balance among adsorption capacity, ion transport, charge storage, and electrochemical stability in coal-derived porous carbons.