title: Anodized Steel Electrodes for Supercapacitors.
abstract: 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.
authors.affiliation: Energy Research Laboratory (ERL), Department of Chemistry, Loughborough University , Loughborough LE11 3TU, United Kingdom.
authors.forename: Jagdeep S
authors.initials: JS
authors.lastname: Sagu
authors.affiliation: Energy Research Laboratory (ERL), Department of Chemistry, Loughborough University , Loughborough LE11 3TU, United Kingdom.
authors.forename: K G Upul
authors.initials: KG
authors.lastname: Wijayantha
authors.affiliation: Swinden Technology Centre, TATA Steel R&D , Moorgate, Rotherham S60 3AR, United Kingdom.
authors.forename: Mallika
authors.initials: M
authors.lastname: Bohm
authors.affiliation: Swinden Technology Centre, TATA Steel R&D , Moorgate, Rotherham S60 3AR, United Kingdom.
authors.forename: Siva
authors.initials: S
authors.lastname: Bohm
authors.affiliation: New Technology Developments & Strategy Planning Research & Development Division, TATA Steel Ltd. , Jamshedpur 831007, India.
authors.forename: Tapan
authors.initials: T
authors.lastname: Kumar Rout
keywords: anodization; electrode; iron oxide; nanostructure; steel; supercapacitor