An ionic liquid-modified reduced graphene oxide electrode material with favourable electrochemical properties

Ionic liquids (ILs) with wide electrochemical windows are increasingly used as electrolytes to improve the energy density of graphene-based supercapacitors. However, due to irreversible agglomeration during the reduction of graphene oxide (GO) to reduced graphene oxide (RGO) and less compatibility between the IL electrolyte and RGO, RGO-based electrode materials in an IL electrolyte usually exhibit poor electrochemical properties. To address these issues, we chose an ionic liquid with a similar structure to the electrolyte as a modifier and fabricated reduced graphene oxide composites modified with the chosen ionic liquid (RGO-IL) by a hydrothermal method. The integration of ILs with RGO could prevent the aggregation and restacking of GO layers and improve the compatibility between the RGO-IL electrode and IL electrolyte. The symmetrical supercapacitor assembled using the obtained RGO-IL2 electrode material showed an outstanding energy density (50.19 W h kg(-1) at 0.75 kW kg(-1)) and excellent cycle performance (87.23% retention of the original value after 2000 cycles at 5 A g(-1)) in the IL electrolyte. These superior performances make RGO-IL composites one of the apposite choices of electrode materials for supercapacitors.