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Synchrotron X-Ray radiography of vanadium redox flow batteries – Time and spatial resolved electrolyte flow in porous carbon electrodes

Köble, Kerstin; Eifert, László; Bevilacqua, Nico; Fahy, Kieran F.; Bazylak, Aimy; Zeis, Roswitha

Abstract:
A porous carbon electrode fully saturated with electrolyte is one crucial aspect of vanadium redox flow battery efficiency. It determines the electrochemically active surface area, provides more active sites for the reaction during operation, and prevents local degradation due to inhomogeneities in electrolyte distribution. We investigate the electrolyte invasion and distribution at open-circuit potential in heat-treated carbon felt electrodes at varying compression ratios and flow field configurations, using synchrotron X-ray radiography. The quantitative analysis yields time-resolved saturation values of the injection and resolves local changes in saturation to detect areas of lower electrolyte accessibility. Compression ratios of 50% and above lead to a high electrode utilization with more than 97% saturation over the felt thickness. In contrast, carbon felts at 25% and 17% compression only reach 49% and 15% saturation near the flow fields. However, increasing the flow velocity after the injection causes the boundary area next to the flow field to fill even at low compressions. This area is especially critical for the electrode utilization since it is invaded after the bulk. ... mehr

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Verlagsausgabe §
DOI: 10.5445/IR/1000130227
Veröffentlicht am 04.03.2021
Originalveröffentlichung
DOI: 10.1016/j.jpowsour.2021.229660
Cover der Publikation
Zugehörige Institution(en) am KIT Helmholtz-Institut Ulm (HIU)
Publikationstyp Zeitschriftenaufsatz
Publikationsmonat/-jahr 04.2021
Sprache Englisch
Identifikator ISSN: 0378-7753
KITopen-ID: 1000130227
Erschienen in Journal of power sources
Verlag Elsevier
Band 492
Seiten Art.-Nr.: 229660
Vorab online veröffentlicht am 23.02.1921
Schlagwörter Synchrotron X-ray visualizationElectrolyte distributionVanadium redox flow batteryCarbon feltCompressionFlow field
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