Comparative kinetic analysis of redox flow battery electrolytes: From micro-fibers to macro-felts

Feynerol, Vincent; Hage, Ranine El; Helú, Mariela Alicia Brites; Fierro, Vanessa; Celzard, Alain; Liu, Liang; Etienne, Mathieu

doi:10.1016/j.electacta.2022.140373

Cited by 8 publications

(10 citation statements)

References 34 publications

(47 reference statements)

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“…A simple examination of the different voltammograms shows the considerable effects of the oxidation treatment on the obtained response in agreement with reports in the literature [ 2 , 4 , 6 ]. Notice that we found large variations with fibers simply rinsed with water (type 1), which could be explained by a non-defined oxidation state.…”

Section: Resultssupporting

confidence: 90%

“…We could also notice that the voltammograms recorded at the lowest scan rate (see Figure 2 ) present a totally S-shape character which is not possible if only considering a cylindrical diffusion with our electrode characteristics. Similar tendency is visible in the voltammograms published in the literature for comparable redox systems [ 6 , 8 ]. This indicates that the experimental diffusion regime differs from the simulation at the lowest scan rate, the more pronounced S-Shape character suggesting the interference of convection on the recorded voltammograms even at the highest scan rates [ 12 ].…”

Section: Resultssupporting

confidence: 86%

“…A reasonable agreement was obtained for the oxidation current with k s value around 1.5 × 10 −4 cm s −1 that is more than two orders smaller than the k s measured on the chemically oxidized fiber for the same couple. C. Amatore et al have provided a very useful model for describing a partially blocked electrode [ 6 ]. This model in its simplified form predicts that for a partially blocked electrode the apparent electron transfer kinetics is affected by the following formula

where

is the fractional coverage of the electrode by the blocking film.…”

Section: Resultsmentioning

confidence: 99%

“…Studying directly a carbon felt is complicated both because it is composed of a variety of fibers and of a three-dimensional porous geometry. To circumvent these difficulties, a useful suggestion was to extract a single fiber from the felt and to study its electrochemical behavior as a model of the felt itself and in the final purpose of an optimization of the electrochemical properties [ 4 , 5 , 6 ]. This approach allows a large simplification of the simulations with providing valuable information on the electrochemical processes.…”

Section: Introductionmentioning

confidence: 99%

“…In these works, examinations of the single fiber mainly rely on impedance spectroscopy and then extended to the felt itself. This approach was recently completed using cyclic voltammetry in combination with numerical simulations to characterize the carbon fiber but in a limited scan rate range [ 6 ]. The rigorous treatment of the system is not obvious as a fiber behaves as a cylinder electrode [ 7 ] with an electrochemical reactivity that is generally not homogeneous on its surface [ 8 , 9 ].…”

Section: Introductionmentioning

confidence: 99%

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Electrochemical Properties of Carbon Fibers from Felts

et al. 2022

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Electrochemical behaviors of individual carbon fibers coming from carbon felts were investigated using two different redox couples, 1,1′-dimethanolferrocene and potassium ferrocyanide. Electrochemical responses were examined after different oxidation treatments, then simulated and interpreted using the Kissa 1D software and existing models. Our experiments indicate that a crude carbon fiber behaves as an assembly of sites with different electrochemical reactivities. In such case, the Butler–Volmer law is not appropriate to describe the electron transfer kinetics because of the large created overpotential. Oxidation of the fiber erases the effect by increasing the kinetics of the electron transfer probably by a homogenization and increase of the reactivity on all the fiber. Additionally, analysis of the signal shows the large influence of the convection that affects the electrochemical response even at moderate scan rates (typically below 0.1–0.2 V s−1).

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Section: Resultssupporting

confidence: 90%