Coal-derived porous activated carbon with ultrahigh specific surface area and excellent electrochemical performance for supercapacitors

Porous activated carbon material is successfully prepared with anthracite through KOH activation. The obtained activated carbon delivers a large specific surface area of 3550.7 m² g⁻¹ with existence of porous structure. The KOH activation introduces numerous hydroxyl groups on the surface of carbon material, improving the wettability of carbon. As electrode for supercapacitor, the material delivers the high specific capacity of 433 F g⁻¹ at the current density of 0.5 A g⁻¹ and it maintains 230 F g⁻¹ even current density reaches up to 50 A g⁻¹. Especially, as electrode for symmetric capacitor, the porous activated carbon exhibits a high specific capacitance of 280 F g⁻¹ and energy density of 38.9 Wh kg⁻¹ at 0.5 A g⁻¹. The material also displays superior cyclic stability without distinct decay in capacity after 30000 cycles. The porous activated carbon material derived from coal, which embodies characteristics of capacitance behavior, may broaden the horizon of electrode materials and provide application prospect for specialized hybrid supercapacitor applications.