LAUSR

Abstract Electrical double layer supercapacitors (EDLC) have an upper limit for their area-normalized capacitance ( C A ) and lead to a bottleneck that impede the commercialization of high-energy-density supercapacitor devices. Quantum capacitance ( C Q ) in series with electrical double layer capacitance ( C EDL ) has been demonstrated to be a tremendous obstacle for enhancing the C A of EDLC. Nitrogen doping can up-shift the Fermi-level and graphitization can improve the density of states (DOS), both of which can significantly mitigate the limiting influence of C Q . Here, a facile approach is developed for synthesizing an ideal carbon-based EDLC electrode material by simply adding ferrous sulfate heptahydrate (FSH) into the polymer when colloid aggregation. The morphology, porous structure, graphitization degree, doped N content and the types of the doped N of the samples can be easily tuned through changing the FSH ratio. The optimized nitrogen doped worm-like hierarchical porous carbon with graphitized porous carbon embossment (NWHC-GE) exhibits an exceptionally high C A (24.6 μF cm −2  at 1 A g −1 and 18.5 μF cm −2  at 100 A g −1 ). This demonstrates a way to enhance the C A and provides a potential strategy for breaking through the limiting specific capacitance of carbon-based materials.