Elucidating effects of cell architecture, electrode material, and solution composition on overpotentials in redox flow batteries

Here, an improved method for quantitative measurement of the charge transfer, finite diffusion, and ohmic overpotentials in redox flow batteries using electrochemical impedance spectroscopy is presented. The use of a pulse dampener in the hydraulic circuit enables the collection of impedance spectra...

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Bibliographic Details
Published in:Electrochimica acta 2017-01, Vol.229 (C)
Main Authors: Pezeshki, Alan M., Sacci, Robert L., Delnick, Frank M., Aaron, Douglas S., Mench, Matthew M.
Format: Article
Language:English
Subjects:
electrochemical impedance spectroscopy
ENERGY STORAGE
finite diffusion resistance
impedance-resolved polarization
INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
rate constant
redox flow battery
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Summary:Here, an improved method for quantitative measurement of the charge transfer, finite diffusion, and ohmic overpotentials in redox flow batteries using electrochemical impedance spectroscopy is presented. The use of a pulse dampener in the hydraulic circuit enables the collection of impedance spectra at low frequencies with a peristaltic pump, allowing the measurement of finite diffusion resistances at operationally relevant flow rates. This method is used to resolve the rate-limiting processes for the V2+/V3+ redox couple on carbon felt and carbon paper electrodes in the vanadium redox flow battery. Carbon felt was limited by both charge transfer and ohmic resistance, while carbon paper was limited by charge transfer, finite diffusion, and ohmic resistances. The influences of vanadium concentration and flow field design also are quantified.
ISSN:0013-4686
1873-3859
DOI:10.1016/j.electacta.2017.01.056