Three-Dimensional Porous Nitrogen doped Graphene Hydrogel for High Energy Density supercapacitors

Abstract Supercapacitors with high power density and long cycle life are of interest to complement lithium-ion batteries. However it is necessary to increase the energy density of supercapacitors for its more widely practical application. In this paper, three-dimensional porous nitrogen-doped graphene hydrogel (N-RGOH) was investigated as supercapacitor electrodes in an ionic liquid electrolyte. The X-ray diffraction, electron microscopy and X-ray photoelectron spectroscopy results show that the N-RGOH displayed 3D porous structure, large specific surface (335.6 m2 g−1) and high nitrogen content (10.8 at%). The electrochemical testing shows that the N-RGOH based supercapacitor device with 3.2 V working voltage delivered a specific capacitance of 48.6 F g−1 at 0.5 A g−1 resulting in a high energy density of 94.5 W h kg−1. The N-RGOH also shows good rate and cycling performances. Our study demonstrates an effective combination of electrode and electrolyte to achieve high energy density supercapacitors for practical application.