Graphene oxide – Ionic liquid composite electrolytes for safe and high-performance supercapacitors

Abstract

Storage devices have been widely reported to satisfy the increase needs in the electronic and transportation areas. The easy access of the electrolyte ions to the surface of the electrodes of carbon nanomaterials is a challenge to be overcome in supercapacitors, especially in the case of ionic liquid electrolytes. Herein, the study of four different ionic liquids (IL) to select the one that exhibits better electrochemical properties in the presence of GO has been accomplished. Among the prepared IL composites, the one with [SET3][TFSI] showed an increase in the conductivity values and an electrochemical stability of over 3.5 V as measured by linear sweep voltammetry. The viscosity of composite [SET3][TFSI]-GO as a function of different concentrations of GO was discussed considering its effect on the conductivity mechanism. Furthermore, supercapacitors based on neat IL and IL-GO 0.1 wt% with reduced graphene oxide (rGO) were investigated. The best results obtained by cyclic voltammetry of the supercapacitor rGO/[SET3][TFSI]/rGO showed a capacitance value of 95.8 F g−1, whereas the supercapacitor rGO/[SET3][TFSI]-GO/rGO exhibited a capacitance of 125.3 F g−1, both at 5 mV s−1, working in a 2.5 V range; which demonstrates an increase of 31% in capacitance because of the presence of GO in the IL. TEM images indicated that the composite electrolyte increases the compatibility of the ionic liquid electrolyte with the rGO electrode, probably favoring the accessibility of the electrolyte ions to the electrode surface.