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 (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 mu F cm(-2) at 1 A g(-1) and 18.5 mu F 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. (C) 2017 Elsevier Ltd. All rights reserved.