Facile Synthesis of N,S-Codoped Hierarchically Porous Carbon with High Volumetric Pseudocapacitance

For the purpose of obtaining high-volumetric-pseudocapacitance carbon materials for supercapacitors, the nitrogen, sulfur-codoped carbon (NSC) with a unique hierarchically porous structure is synthesized by directly carbonizing the unpurified polyaniline/sodium alginate hydrogel without additional activation processes. Owing to the unique nanoporous structure and synergistic effect of high contents of nitrogen (8.4 atom %), sulfur (1.4 atom %), and oxygen (12.8 atom %), the NSC exhibits typical pseudocapacitive behavior and high specific capacitance (309 F g–1 at 0.5 A g–1). Meanwhile, the high density of the NSC electrode (1.15 g cm–3) results in high volumetric capacitance (355 F cm–3 at 0.5 A g–1). Furthermore, two NSC electrodes are employed to assemble a high-operation-potential symmetric supercapacitor (1.6 V), which achieves an excellent energy density of 15.9 Wh L–1 with the power density of 426 W L–1. The facile synthesis provides a superior strategy for fabricating N,S-codoped nanoporous carbons with high volumetric pseudocapacitance.