Polyaniline–poly(styrene sulfonate) hydrogel derived hierarchically porous N, S-codoped carbon for high-performance supercapacitors

On account of the limited energy density of carbon-based supercapacitors, the heteroatom-doped carbons with hierarchically porous structure are extensively developed. Unfortunately, the facile synthesis remains a huge challenge. Herein, a hierarchically porous N, S-codoped carbon is prepared by carbonizing the conducting polymer hydrogel of polyaniline–poly(styrene sulfonate) (PANI–PSS), in which the PANI and PSS act as nitrogen and sulfur sources, respectively. Owing to inherent porous structure of hydrogel, and the pore-forming effects of Na+ ions and the inorganic byproducts, the resultant carbons exhibit ideal hierarchically porous structure with high specific surface area. The electrochemical performance is investigated by using cyclic voltammetry, electrochemical impedance spectroscopy, and galvanostatic charge–discharge, and the results show that the product prepared at 750 °C (NSC-750) exhibits the highest specific capacitance (376 F g−1 at 0.5 A g−1), and the smallest inner impedance, originating from its highest specific surface area (755 m2 g−1) and moderate doping of heteroatoms. The feasibility of product is demonstrated by the NSC-750 symmetric supercapacitor, which delivered high energy density of 11.7 Wh kg−1 with a power density of 250 W kg−1. The hydrogel-derived hierarchically porous N, S-codoped carbon with superior electrochemical performance highlights a facile and feasible pathway to synthesize high-performance carbons for supercapacitors.