Porous carbon with a large surface area and an ultrahigh carbon purity via templating carbonization coupling with KOH activation as excellent supercapacitor electrode materials

Large surface area and good structural stability, for porous carbons, are two crucial requirements to enable the constructed supercapacitors with high capacitance and long cycling lifespan. Herein, we successfully prepare porous carbon with a large surface area (3175 m ²  g ⁻¹ ) and an ultrahigh carbon purity (carbon atom ratio of 98.25%) via templating carbonization coupling with KOH activation. As-synthesized MTC-KOH exhibits excellent performances as supercapacitor electrode materials in terms of high specific capacitance and ultrahigh cycling stability. In a three electrode system, MTC-KOH delivers a high capacitance of 275 F g ⁻¹ at 0.5 A g ⁻¹ and still 120 F g ⁻¹ at a high rate of 30 A g ⁻¹ . There is almost no capacitance decay even after 10,000 cycles, demonstrating outstanding cycling stability. In comparison, pre-activated MTC with a hierarchical pore structure shows a better rate capability than microporous MTC-KOH. Moreover, the constructed symmetric supercapacitor using MTC-KOH can achieve high energy densities of 8.68 Wh kg ⁻¹ and 4.03 Wh kg ⁻¹ with the corresponding power densities of 108 W kg ⁻¹ and 6.49 kW kg ⁻¹ , respectively. Our work provides a simple design strategy to prepare highly porous carbons with high carbon purity for supercapacitors application.