An efficient two-step approach for improvement of graphene aerogel characteristics in preparation of supercapacitor electrodes

We fabricated a high rate capability supercapacitor based on fluorine-doped graphene-carbon nanotubes aerogel network (G-CNT-F). Based on the electrochemical impedance spectroscopy data, the fluorination decreases the charge transfer resistance of graphene sheets, while CNTs act as spacer in the 3D structure. Therefore, both treatments improved the electrochemical properties of the resulted aerogel. Based on the Fourier transform infrared spectroscopy and XPS results, these excellent performances are attributed to semi-ionic bonds between fluorine and carbon. The specific capacitance of the graphene aerogel showed 78% decrease, when discharge current increases from 2 to 40 mA, while the G-CNT and G-CNT-F electrode loses 63.8 and 33.3% of its specific capacitance, respectively. The fabricated symmetric supercapacitor based on G-CNT-F shows energy density as high as 9.9 Wh/kg at the power density of 6000 W/kg in aqueous electrolytes.