N/S co-doped interconnected 3D carbon frameworks for aqueous and high voltage flexible quasi-solid-state supercapacitors

Heteroatoms co-doped porous carbon attracts tremendous research interest for electrochemical energy storage applications. We demonstrate herein N/S co-doped 3D carbon frameworks with the large specific surface area through KOH activation in the presence of KSCN by utilizing red bean as the precursor. We found that KSCN can not only act as the N/S sources but also serve as the co-activator to generate nanopores. Benefitting from its large specific surface, hierarchical porosity, and N/S co-doping, the largest specific capacitance can be reached 293.4 F g−1 (at 0.5 A g−1) and satisfactory rate capability of 68% (at 50 A g−1) in 6 M KOH aqueous electrolyte. Encouragingly, a high-energy density achieves to 23.025 Wh kg−1 can be obtained and in Na2SO4/PVA gel electrolyte within the voltage window of 0–1.8 V. The quasi-solid-state supercapacitor could also be connected in series or parallel to further enhance the working voltage or current.