Nanostructured MnO2/exfoliated graphite composite electrode as supercapacitors

Abstract Nanostructured manganese oxides/exfoliated graphite composite (MnO 2 /EG) were synthesized via a new sol–gel route. Scanning electron microscope (SEM) was employed for surface morphology and X-ray diffraction (XRD) was used for structure characterization. Cyclic voltammetry (CV), galvanostatic charge/discharge, and the electrochemical impedance measurements were applied to investigate the electrochemical performance of the MnO 2 /EG composite electrodes. When used for electrodes of supercapacitors, the as-prepared MnO 2 /EG and the pure MnO 2 exhibited excellent capacitance characteristics in 6 mol L −1 KOH electrolyte and showed high specific capacitance values of 398 F g −1 and 326 F g −1 ,respectively, at a scan rate of 10 mV s −1 . The galvanostatic charge–discharge measurements showed approximately 0.5% loss of capacitance after 500 cycles, and charge–discharge efficiency above 99%. In addition, the synthesized nanomaterial showed a good reversibility and cycling stability.