Performance evaluation of thermally treated graphite felt electrodes for vanadium redox flow battery and their four-point single cell characterization

Mazúr, Petr; Mrlík, Jindřich; Beneš, Jan; Pocedič, Jaromír; Vrána, Jiří; Dundálek, Jan; Košek, Juraj

doi:10.1016/j.jpowsour.2018.01.079

Cited by 63 publications

(38 citation statements)

References 35 publications

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“…As expected, the positive double-half cells show a significantly lower DHC resistance due to the higher conductivity of the positive electrolyte and the faster kinetics of the positive couple. This is highly consistent with previous studies [29,[41][42][43]. Similarly, a clear distinction between DHCs built using NR-211 and NR-212 membranes is observed.…”

Section: Double Half-cell Measurementssupporting

confidence: 92%

“…Volumetric exchange current densities (j •S ) of negative and positive couples differ by almost two orders of magnitude (ratio positive to negative of between 40 and 51 depending on the temperature). A similar ratio has been observed in previous investigations, which performed a deconvolution of voltage losses by means of single-electrode impedance spectroscopy and reference electrodes [42,43]. For the sake of comparison with previous studies based on different methodologies, we estimated S by multiplying the BET surface area of the felt (3.8 m 2 g -1 ) by its bulk density (0.09 g cm −3 ).…”

Section: Double Half-cell Measurementsmentioning

confidence: 67%

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Effect of Operating Temperature on Individual Half-Cell Reactions in All-Vanadium Redox Flow Batteries

2018

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Systematic steady-state measurements were performed in order to investigate the effect of operating temperature on the individual half-cell reactions in all vanadium redox flow cells. Results confirm that the kinetic losses are dominated by the negative half-cell reaction. Steady-state polarization and AC impedance measurements allowed for extraction of kinetic parameters (exchange current densities, activation energy) of the corresponding half-cell reaction.

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Section: Double Half-cell Measurementssupporting

confidence: 92%

Section: Double Half-cell Measurementsmentioning

confidence: 67%

Effect of Operating Temperature on Individual Half-Cell Reactions in All-Vanadium Redox Flow Batteries

2018

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“…The optimal thermal treatment conditions for the graphite felt were found to be 400 • C for 30 h. The improved performance was attributed to the increased number of surface oxygen functional groups that increased the hydropilicity of the graphite felt while providing active sites for the vanadium redox couple reactions. Other examples of thermal treatment have been mentioned above and some experimental details have been previously reviewed [307]. Heat-treatment of carbon felt under airless conditions for use as positive and negative electrode material has been examined [308].…”

Section: Mechanical Thermal or Chemical Surface Treatmentmentioning

confidence: 99%

Electrocatalysis at Electrodes for Vanadium Redox Flow Batteries

Holze

2018

Batteries

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Flow batteries (also: redox batteries or redox flow batteries RFB) are briefly introduced as systems for conversion and storage of electrical energy into chemical energy and back. Their place in the wide range of systems and processes for energy conversion and storage is outlined. Acceleration of electrochemical charge transfer for vanadium-based redox systems desired for improved performance efficiency of these systems is reviewed in detail; relevant data pertaining to other redox systems are added when possibly meriting attention. An attempt is made to separate effects simply caused by enlarged electrochemically active surface area and true (specific) electrocatalytic activity. Because this requires proper definition of the experimental setup and careful examination of experimental results, electrochemical methods employed in the reviewed studies are described first.

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“…Meanwhile, the reduction peak currents of the samples in −0.8 V (vs SCE) position display that I pc (T ‐ CF) > I pc (T ‐ GF) > I pc (CF) > I pc (GF). Therefore, the increase in the number of oxygen functional groups of T‐GF and T‐CF caused by hot air can be recognized as an effective mean to improve electrode activity in ICRFBs …”

Section: Resultsmentioning

confidence: 96%

“…Therefore, the increase in the number of oxygen functional groups of T-GF and T-CF caused by hot air can be recognized as an effective mean to improve electrode activity in ICRFBs. [45][46][47] Figure 8 compares EIS spectra of each sample at polarization overpotential (η) of 0.4 V (vs SCE) ( Figure 8A) and −0.5 V (vs SCE) ( Figure 8B). In Figure 8, all EIS spectra are composed of a semicircle and linear parts.…”

Section: And Eis Analysismentioning

confidence: 99%

Investigations on physicochemical properties and electrochemical performance of graphite felt and carbon felt for iron‐chromium redox flow battery

et al. 2020

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Summary In this paper, polyacrylonitrile‐based graphite felt (GF), carbon felt (CF) and the effect of thermal activation on them with or without the catalyst (BiCl3) are comprehensively investigated for iron‐chromium redox flow battery (ICRFB) application. The physical‐chemical parameters of GF and CF after the thermal activation is affected significantly by their graphitization degree, oxygen functional groups, and surface area. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) results manifest that GF and CF before and after the thermal activation have different electrocatalytic activities owing to oxygen functional groups number increase and the graphitization degree decrease. In terms of the capacity decay rate, as oxygen functional groups provide shorter electrocatalytic pathways than bismuth ions, the performance of GF and CF after the thermal activation is more ideal. As a result, GF before and after the thermal activation exhibits higher efficiency (EE: 86%) and better stability at a charge‐discharge current density of 60 mA·cm−2 than those of CF during charge‐discharge cycling, as the dominant limitation in an ICRFB is ohmic and activation polarization. Therefore, GF after thermal activation together with the addition of BiCl3 in the electrolyte is a more promising electrode material for ICRFBs application than CF.

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Performance evaluation of thermally treated graphite felt electrodes for vanadium redox flow battery and their four-point single cell characterization

Cited by 63 publications

References 35 publications

Effect of Operating Temperature on Individual Half-Cell Reactions in All-Vanadium Redox Flow Batteries

Effect of Operating Temperature on Individual Half-Cell Reactions in All-Vanadium Redox Flow Batteries

Electrocatalysis at Electrodes for Vanadium Redox Flow Batteries

Investigations on physicochemical properties and electrochemical performance of graphite felt and carbon felt for iron‐chromium redox flow battery

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