Specifying the Effects of Functionalization of Highly Reduced Graphene Oxide by an Ionic Liquid on Supercapacitive Features

Graphene-based supercapacitors are interesting types of energy storage devices which are able to offer more capacitance than other types of electric double-layer capacitors (EDLCs). Appropriate electrical conductivity and high specific surface area are two main features of graphene as an electrode material in EDLCs. Functionalization of graphene systems with appropriate ionic liquids could eliminate agglomeration of graphene plates and enhance the available surface area, especially for ionic liquid electrolytes. In this paper, reduced graphene oxide (RGO) by hydrazine is functionalized with butyl methyl imidazolium ionic liquid, where ionic liquid-functionalized partially reduced graphene oxide (IFG) was produced. RGO and IFG had specific capacitance values of about 262.5 F/g and 436.7 F/g, respectively. IFG showed higher specific capacitance than RGO due to its novel three-dimensional (3D) structure. Fourier transform infrared spectroscopy, x-ray diffraction, Raman spectroscopy, Brunauer–Emmett–Teller analysis, cyclic voltammetry tests, electrochemical impedance spectroscopy, galvanostatic charge/discharge cycling stability analysis, and scanning electron microscopy were used for analyzing RGO and IFG.