Preparation of nitrogen and sulfur co-doped graphene aerogel with hierarchical porous structure using ionic liquid precursor for high-performance supercapacitor

Abstract

In this paper, nitrogen and sulfur co-doped graphene aerogel (NS-GA) was successfully prepared using ionic liquid 1-(4-mercaptobutyl)-3-methylimidazolium bromide (HS-BMIMBr) as both reductant and dopant by a one-step hydrothermal method. The results of X-ray diffraction indicate that the doping of heteroatoms into graphene increases its degree of defects. In addition, scanning electron microscopy measurements and nitrogen adsorption–desorption analysis reveal that the as-prepared NS-GA has unique hierarchical porous nanostructures, which supply efficient networks for ionic transports and electron transfer. The symmetric electrical double-layer capacitors (EDLCs) based on the NS-GA with ionic liquid (1-ethyl-3-methylimidazolium tetrafluoroborate, EMIMBF4) as the electrolyte show excellent capacitive performance. And the NS-GA has a high specific capacitance of 182.3 F g−1 at a current density of 1 A g−1. Moreover, there is a high energy density of 101 Wh kg−1 at a power density of 1 kW kg−1. Therefore, the NS-GA can be considered as a favorable electrode material for high-performance energy storage devices.