N/O co-doped microporous carbon as a high-performance electrode for supercapacitors

Carbon materials with adjustable porosity, controllable heteroatom doping and low-cost have been received considerable attention as supercapacitor electrodes. However, using carbon materials with abundant micropores, a high surface area and a high-dopant content for an aqueous supercapacitor with a high energy output still remains a challenge. We report the easy synthesis of interconnected carbon spheres by a polymerization reaction between p -benzaldehyde and 2,6-diaminopyridine. The synthesis involves adjusting the mass ratio of the copolymer and KOH activator to achieve increased charge storage ability and high energy output, which are attributed to the high ion-accessible area provided by the large number of micropores, high N/O contents and rapid ion diffusion channels in the porous structure. At a PMEC∶KOH mass ratio of 1∶1, the high electrolyte ion-adsorption area (2599.76 m 2 g −1 ) and the N/O dopant atoms of the conductive framework of a typical carbon electrode produce a superior specific capacity (303.2 F g −1 @0.5 A g −1 ) giving an assembled symmetric capacitor a high energy delivery of 11.3 Wh kg −1 @250 W kg −1 . This study presents a simple strategy for synthesizing microporous carbon and highlights its potential use in KOH-based supercapacitors.