Optimization of Electrochemical Performance for Activated Carbon and Functionalized Graphene Composite-Based Supercapacitor

In this paper, we optimize the ratio of activated carbon (AC) and reduced graphene oxide (rGO) to fabricate their composite to improve the electrochemical performances of the rGO/AC composite-based supercapacitor. In addition, the rGO is functionalized by using an ionic liquid (F-rGO) as 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIBF4) to enhance wettability and compatibility between electrode and electrolyte. The electrochemical performances of F-rGO and AC (F-rGO/AC-15) composite-based supercapacitor are evaluated by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and galvanostatic charge/discharge tests (GCD). The F-rGO/AC-15 composite (15:85, w/w %)-based supercapacitor indicates low charge transfer resistance (0.41 Ω) when compares to the rGO/AC-15 composite-based supercapacitor (0.6 Ω). In addition, F-rGO/AC-15 composite-based supercapacitor shows high energy density of 146 Wh kg−1, while pristine AC-based supercapacitor showed energy density of 50.1 Wh kg−1 with 416.6 W kg−1 of power density. The F-rGO/AC-15 composite-based supercapacitor also shows the enhanced specific capacitance of 127 F g−1.