Evaluation of aluminium doped spinel ferrite electrodes for supercapacitors

Abstract

Al-doped copper cobalt ferrites are synthesized via the sol–gel method and evaluated as potential supercapacitor electrodes. Their structure and surface morphology are studied by using X-ray diffraction analysis, energy dispersive X-ray spectroscopy, Brunauer–Emmett–Teller surface adsorption and scanning electron microscopy. The SEM images show changes in the morphology of the as-produced nanocomposites with an increase in the percentage of aluminium doping. The effects of varying Al content on the electrochemical behaviours of AlxCuyCozFe2O4 (where x+y+z=1) are investigated by cyclic voltammetry, galvanostatic charge/discharge and electrochemical impedance spectroscopy. Among the synthesised nanomaterials, aluminium doped copper–cobalt ferrite, Al0.2Cu0.4Co0.4Fe2O4, exhibits the highest specific capacitance of 548Fg−1 at a scan rate of 100mVs−1 with energy and power densities of 3.84Whkg−1 and 270Whkg−1 respectively. The improved electrochemical performance can be attributed to the high electrical conductivity of the synthesised aluminium-doped copper cobalt ferrite nanocomposites.