Nano ZnO-activated carbon composite electrodes for supercapacitors

Abstract

A symmetrical (p/p) supercapacitor has been fabricated by making use of nanostructured zinc oxide (ZnO)-activated carbon (AC) composite electrodes for the first time. The composites have been characterized by field emission scanning electron microscopy (FESEM) and X-ray diffraction analysis (XRD). Electrochemical properties of the prepared nanocomposite electrodes and the supercapacitor have been studied using cyclic voltammetry (CV) and AC impedance spectroscopy in 0.1 M Na<inf>2</inf>SO<inf>4</inf> as electrolyte. The ZnO-AC nanocomposite electrode showed a specific capacitance of 160 F/g for 1:1 composition. The specific capacitance of the electrodes decreased with increase in zinc oxide content. Galvanostatic charge-discharge measurements have been done at various current densities, namely 2, 4, 6 and 7 mA/cm2. It has been found that the cells have excellent electrochemical reversibility and capacitive characteristics in 0.1 M Na<inf>2</inf>SO<inf>4</inf> electrolyte. It has also been observed that the specific capacitance is constant up to 500 cycles at all current densities. © 2010 Elsevier B.V. All rights reserved.