Synthesis and electrochemical properties of MnO2 nanorods/graphene composites for supercapacitor applications

MnO2 nanorods/graphene composite materials have been fabricated using a facile hydrothermal method for supercapacitor applications. The prepared composite materials are characterized by means of X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and transmission electron microscope (TEM). Electrochemical performances are evaluated using cyclic voltammetry (CV), galvanostatic charge–discharge and electrochemical impedance spectrometry (EIS). It indicates that ratio of MnO2 nanorods to graphene in composite materials has significant influence on the electrochemical performance of composite electrodes. We have achieved the maximum specific capacitance of 218 F g−1 at the scan rate of 5 mV s−1 in 1 M Na2SO4 aqueous solution. Additionally, MnO2 nanorods/graphene composite materials exhibit highest energy density of 16 Wh kg−1 at power density of 95 W kg−1 and excellent capacitance retention with no more than 6% capacitance loss after 1000 cycles at the most favorable composites ratio.