Chemical co-activated modified small mesoporous carbon derived from nature anthracite toward enhanced supercapacitive behaviors

Ultrapure anthracite-derived PCs were successfully synthesized via acid-alkali synergic activation to achieve the pore-expanding and surface chemical stabilization. The resultant abundant small mesoporous net and improved carbon surface stability can effectively boost ions diffusion and capacitance reversibility, resulting in a low internal resistance and superior rate capability at high current, thus greatly enhancing supercapacitive behaviors. • Ultrapure anthracite-derived PC with small mesopore development and stable surface chemistry is achieved. • The optimum carbon displays a high mesopore ratio of up to 71.89%. • The combination of bigger micropores and smaller mesopores is effective for rapid ions diffusion. • High-current rate capability and capacitance reversibility are significantly improved. Chemical co-activation is a valid avenue to achieve the surface chemical modification and pore configuration regulation of carbon electrode materials, thus greatly facilitating their capacitive behaviors. In the study, ultrapure anthracite-derived porous carbons (PCs) with small mesopore development are synthesized via KOH pre-etching of natural coal for pore-creating, closely followed by H 3 PO 4 deep activation for pore-expanding and carbon surface stabilization. Phosphoric acid post-activation under increased temperature not only creates abundant small mesopores for fast ions transport, but improves the surface chemistry on carbon skeleton to boost the capacitance reversibility. When assessed as electro-chemical double-layer capacitor (EDLC) electrodes in KOH electrolyte, the resulting co-activated PC demonstrates low internal resistance of less than 2.50 mΩ, high specific capacity of up to 212F g −1 , and superior rate capability of 71.82% at 10 A g −1 . More importantly, due to the enhancement of oxidation stability of optimal electrode by the reduction of unstable chemical groups on carbon surface, the constructed organic supercapacitor can be quickly charged or discharged for a long period in 1 m (C 2 H 5 ) 4 NBF 4 electrolyte, so as to deliver an excellent cycling stability of 97.52% capacitance retention. This study realizes the high value-added and efficiently clean utilization of anthracite as a non-renewable resource, as well as offering profound electrochemical insights for large scale application of small mesoporous carbon towards next-generation high-power smart devices.