High performance asymmetric supercapacitor from manganese oxide–carbon nanotube based composite electrode

Development of transition metal oxide-carbon composites have gained interest in recent years owing to their potential applications requiring both high energy and high power densities, which are much sought in present day portable electronics, specially supercapacitors. Supercapacitors (ultracapacitors) are attractive energy source because of high power density, fast energy delivery, short charge time, long shelf and cycle life and safety over than battery. Carbon nanotubes (CNTs) have been already proposed as electrode materials for supercapacitors. How ever, CNTs filled and doped with mixed metal oxides show more attractive electrodes than Pure CNTs. In this paper a nanocomposite consisting of carbon nanotubes and MnO2 is synthesised by mixing carbon nanotubes and manganese nitrate together with different ratios using wet chemical method. Due to test supercapacitance properties of the electrode, an asymmetric type pseudo-capacitor/electric double layer capacitor is considered and its electrochemical properties are investigated. By using the as-prepared cathode of a MnO2-carbon nanotube composite electrode, the asymmetric supercapacitor exhibits high energy density, stable power and short charge-discharge time. The redox properties of the nanocomposite are exhibited ideal capacitive behaviour in a KOH solution. The morphological characterization of this nanocomposite is examined in terms of the X-ray diffraction patterns (XRD) and transmission electron microscopy (TEM) images. Cyclic voltammetry, galvanostatic charging/discharging tests were applied to investigate the performance of the composite electrodes. The results demonstrate that electrochemical properties of MnO2/CNT electrode are significantly greater than pristine CNTs electrode in the same medium.

کلیدواژه ها:

Carbon nanotube ، MnO2 composite ، Supercapacitor ، Electrochemical properties