N-doped reduced graphene oxide aerogel coated on carboxyl-modified carbon fiber paper for high-performance ionic-liquid supercapacitors

Nitrogen-doped reduced graphene oxide aerogel (N-rGO aerogel) with high porosity and ionic conductivity were synthesized by a hydrothermal reduction of graphene oxide with hydrazine and following freezing-dry method. N-rGO aerogel was spray-coated on carboxyl-modified carbon fiber paper with a hydrophilic surface and used as the supercapacitor electrode. Not only can the N-rGO aerogel electrode accelerate the diffusion of the electrolyte but also it can store electronic charge via a surface redox reaction due to the N-containing groups. Among the electrolytes studied, the ionic liquid-based supercapacitor of the N-rGO aerogel provides a wide working potential of ca. 4.0 V and rather high specific capacitance of 764.53 F/g at 1 A/g with a capacity retention of 86% over 3000 charge-discharge cycles as well as maximum specific power and energy of 6525.56 W/kg and 245.00 Wh/kg, respectively. The device prototype fabricated in a single coin cell shape (CR2016) can supply electricity to red LED over 17 min.