Supercapacitor Electrode from Activated Carbon and Graphene Composite with PVDF-HFP Binder

Electrochemical double-layer supercapacitor electrodes were produced using an activated carbon monolith (ACM) powder as the precursor and graphene as the additive. Electrodes were prepared by mixing ACM powder and graphene with different weight percentage (0, 5, 10, 20 and 40 wt. %) which were added with poly-vinylidene fluoride-hexafluoropropylene (PVDF-HFP) solution as a binding agent and carbon black as a conductive agent. Physical characterization was carried out on the electrodes by using an X-ray diffraction (XRD) and adsorption-desorption isotherms methods. Supercapacitor cells performance using 6 M KOH aqueous electrolyte were tested using electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and galvanostatic charge discharges (GCD) methods. Supercapacitor cell with 5 wt. % graphene additive (KMT05) was found to have the highest specific capacitance (172 F g(-1)), highest specific energy (11 Wh kg(-1)), highest specific power (196.13 W kg(-1)), lowest response time (2 s), and lowest charge transfer resistance (2.4 Omega) compared to other cells. This showed that 5 wt. % graphene additive is optimum for improving the cell performance. These results are compatible with the larger microcrystallites size and specific surface area of KMT05X have a larger compared to the KMT with no graphene additive (KMT00X).