Comparison of ionic liquid electrolyte to aqueous electrolytes on carbon nanofibres supercapacitor electrode derived from oxygen-functionalized graphene

Abstract

A facial force-driven reflux technique was used to develop fibre-like carbon material from freeze-dried reduced graphene oxide (RGO) firstly prepared by using a modified Hummers method. The carbon nanofibres displayed a high specific surface area of ∼1317.8 m2 g−1, with good pore size distributions which could be beneficial for energy storage applications. Electrochemical measurements of the carbon nanofibre electrodes in a symmetric configuration with aqueous (1 M Na2SO4, 6 M KOH), and protic ionic liquid (1-ethylimidazolium bis(trifluoromethanesulfonly)imide) electrolytes (ILE) displayed excellent electrochemical performance with the dominant electric double layer capacitor (EDLC) behaviour. The fabricated device shows higher electrochemical performance in the ILE due to its larger cell operating potential (3.0 V) as compared with the aqueous electrolytes (0.8 V). The optimized electrochemical properties especially in terms of higher specific energy and superior stability, suggest the material’s potential applications as electrode for supercapacitors.