Electrode Kinetics of Vanadium Flow Batteries: Contrasting Responses of VII-VIII and VIV-VV to Electrochemical Pretreatment of Carbon. Issue 1 (23rd October 2015)

• Record Type: Journal Article
• Authors: Bourke, A.; Miller, M. A.; Lynch, R. P.; Gao, X.; Landon, J.; Wainright, J. S.; Savinell, R. F.; Buckley, D. N.
• Is Part Of: Journal of the Electrochemical Society. Volume 163:Issue 1(2016)
• Page Start: A5097
• Page End: A5105
• Publication Date: 2015-10-23
• Subjects: Activation -- Anodic and Cathodic Treatment -- Carbon Electrode -- Carbon Felt -- Carbon Fiber -- Electrode Kinetics -- Glassy Carbon -- Graphite -- Reticulated Vitreous Carbon -- Vanadium Redox Flow Battery; Electrochemistry -- Periodicals; 541.3705
• DOI: 10.1149/2.0131601jes
• Languages: English
• ISSNs: 0013-4651

Abstract

Abstract : Electrochemical impedance spectroscopy and cyclic voltammetry were used to investigate the electrode kinetics of V II -V III and V IV -V V in H2 SO4 on glassy carbon, carbon paper, carbon xerogel, and carbon fibers. It was shown that, for all carbon materials investigated, the kinetics of V II -V III is enhanced by anodic, and inhibited by cathodic, treatment of the electrode; in contrast, the kinetics of V IV -V V is inhibited by anodic, and enhanced by cathodic, treatment. The potential region for each of these effects varied only slightly with carbon material. Rate constants were always greater for V IV -V V than for V II -V III except when anodized electrodes were compared, which may explain discrepancies in the literature. The observed effects are attributed to oxygen-containing functional-groups on the electrode surface. The considerable differences between the potentials at which enhancement of V II -V III and inhibition of V IV -V V occur indicates that they do not correspond to a common oxidized state of the electrode. Likewise inhibition of V II -V III and enhancement of V IV -V V do not correspond to a common reduced state of the electrode. It is possible that enhancement of both V II -V III and V IV -V V is due to the same (active) state of the electrode.