Power Saving Electrochemical Processing of Low Cost MnO2@Porous Al Electrode for High Performance Supercapacitors Applications

Abstract

The supercapactive properties for MnO2 coated on porous aluminum foil Al electrodes etched using various acidic baths and ethylene glycol (EG) as additive was studied. The optimum current densities for achieving high porous surface of Al foils using galvanostatic technique are 70 and 90 mA/cm2 in case of etching from acidic solution and when ethylene glycol is added respectively. Furthermore, cyclic voltammetry, galvanostatic charge-discharge techniques and electrochemical impedance spectroscopy were performed to determine specific capacitance and cycle life of the MnO2@ porous Al foil and MnO2@porous Al-EG electrode using 0.5 M Na2SO4 as electrolyte. The cyclic voltammteric curves for the two electrodes reveal that psuedocapacitive behavior during oxidartion - reduction reaction with maximum specific capacity 221.5 F/g at scan rate 20 mV/s for MnO2@ porous Al electrode. Moreover, the galvanostatic charge-discharge tests for MnO2@porous Al electrode at current densities 0.5 and 1 A/g show good pseudocapacitive performance and cycle ability with nearly linear curves forming quite triangle shape. Also, The EIS curves for both electrodes elucidate that, the total impedance of MnO2@porous Al cell is smaller than that of MnO2@porous Al-EG cell, so, MnO2@porous Al electrode has a high ionic conductivity between active material and ionic species. In addition to, both electrodes posse's quite similar capacitive retention about 75% after 1000 cycles and this reveals the good adhesion and less dissolution of MnO2 film.