Abstract
The kinetics of redox reactions relevant to vanadium redox flow battery (VRFB) is investigated using voltammetry (CV) and electrochemical impedance spectroscopy (EIS) in a three-electrode configuration and in a VRFB setup (two-electrode configuration). Impedance spectra are recorded in the VRFB setup with equimolar concentration of V5+/V4+ and V3+/V2+ solutions as positive and negative electrolytes, respectively (full-cell; asymmetric feed system); with an equimolar V5+/V4+ electrolyte on both sides (symmetric feed system 1); and also with V3+/V2+ electrolyte on both sides (symmetric feed system 2). Impedance of the full-cell VRFB (recorded with asymmetric feed system) is comparable to the sum of the half of the impedance of symmetric feed systems (of V5+/V4+ and V3+/V2+ electrolytes) at open circuit potential (OCP). Impedance and voltammograms recorded in the three-electrode configuration using Vulcan XC-72 modified rotating disk electrode, and the impedance recorded in the two-electrode full-cell configuration unequivocally confirms that the V5+/V4+ redox reaction limits the VRFB performance. The optimal performance of the VRFB with the in situ treated carbon felt compressed to 47% is ∼389 and ∼336 mW cm−2 with 5 and 25 cm2 cell area, respectively.
Publisher
The Electrochemical Society
Subject
Materials Chemistry,Electrochemistry,Surfaces, Coatings and Films,Condensed Matter Physics,Renewable Energy, Sustainability and the Environment,Electronic, Optical and Magnetic Materials
Cited by
4 articles.
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