Electrolyte-dependent Specific Capacitance and Charge Transfer Properties of Exfoliated Graphene as an Electrode of Supercapacitor

The specific capacitance and charge transfer properties of electrochemically exfoliated graphene (EG) are studied using various alkaline electrolytes. Scanning Electron Microscopy (SEM) and Raman spectroscopy results confirm the successful exfoliation of graphite into EG using electrochemical treatment. At similar concentrations, the prepared EG electrodes were then evaluated using different alkaline electrolytes, including LiOH, NaOH, and KOH. Cyclic voltammetry (CV) characterization result demonstrates that 1M KOH exhibits the highest specific capacitance $(116.04 \mathrm{Fg}^{-1})$, followed by 1M LiOH $(67.29 \mathrm{Fg}^{-1})$ and 1M NaOH $(88.26 \mathrm{Fg}^{-1})$. Electrochemical impedance spectroscopy (EIS) result indicates that the sample tested using 1M KOH exhibits the fastest charge transfer and easiest ions penetration into graphene interlayers compared to 1M LiOH and 1M NaOH. These results indicate that the KOH electrolyte is promising for realizing a high energy and power density of EG-based supercapacitor electrodes.