Anodized steel electrodes for supercapacitors
journal contributionposted on 04.04.2016, 12:41 by Jagdeep Sagu, Upul Wijayantha-Kahagala-GamageUpul Wijayantha-Kahagala-Gamage, Mallika Bohm, Siva Bohm, Tapan Kumar Rout
Steel was anodized in 10 M NaOH to enhance its surface texture and internal surface area for application as an electrode in supercapacitors. A mechanism was proposed for the anodization process. Field-emission gun scanning electron microscopy (FEGSEM) studies of anodized steel revealed that it contains a highly porous sponge like structure ideal for supercapacitor electrodes. X-ray photoelectron spectroscopy (XPS) measurements showed that the surface of the anodized steel was Fe2O3, whereas X-ray diffraction (XRD) measurements indicated that the bulk remained as metallic Fe. The supercapacitor performance of the anodized steel was tested in 1 M NaOH and a capacitance of 18 mF cm-2 was obtained. Cyclic voltammetry measurements showed that there was a large psueudocapacitive contribution which was due to oxidation of Fe to Fe(OH)2 and then further oxidation to FeOOH, and the respective reduction of these species back to metallic Fe. These redox processes were found to be remarkably reversible as the electrode showed no loss in capacitance after 10000 cycles. The results demonstrate that anodization of steel is a suitable method to produce high-surface-area electrodes for supercapacitors with excellent cycling lifetime.
J.S. thanks Loughborough University and Tata Steel for the PhD studentship to conduct this work. All authors acknowledge the support given by members of the energy research lab (ERL) at the Department of Chemistry, Loughborough University. KGUW would like to acknowledge the support received from RCUK to conduct this research.