Nitrogen-doped worm-like graphitized hierarchical porous carbon designed for enhancing area-normalized capacitance of electrical double layer supercapacitors

Electrical double layer supercapacitors (EDLC) have an upper limit for their area-normalized capacitance (CA) and lead to a bottleneck that impede the commercialization of high-energy-density supercapacitor devices. Quantum capacitance (CQ) in series with electrical double layer capacitance (CEDL) has been demonstrated to be a tremendous obstacle for enhancing the CA 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 CQ. 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 CA (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 CA and provides a potential strategy for breaking through the limiting specific capacitance of carbon-based materials.

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