Requirements for optimization of electrodes and electrolyte for the iron/chromium redox flow cell

Jalan, V.; Stärk, Hans‐Joachim; Giner, J.

doi:10.2172/5328915

Cited by 6 publications

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“…The electrodes were made of carbon felt (No. 42107, Alfa Aesar), which were pretreated by the literature methods. , The cutoff voltages were 1.7 and 0.8 V for charging and discharging, respectively, for the VRFB, and were 1.25 and 0.6 V for charge and discharge, respectively, for the FCRFB. The VRFB used a solution of 2 M V 2+ /V 3+ sulfates in 2 M H 2 SO 4 as anolyte and a solution of 2 M V 5+ /V 4+ (VO 2 + /VO 2+ ) sulfates in 2 M H 2 SO 4 as catholyte.…”

Section: Methodsmentioning

confidence: 99%

Proton-Selective Ion Transport in ZSM-5 Zeolite Membrane

Michos

Cao

et al. 2016

J. Phys. Chem. C

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The ionic ZSM-5 zeolite membranes were investigated for proton-selective ion separation in electrolyte solutions relevant to redox flow batteries. The zeolite membrane achieved exceptional selectivity for proton over V4+ (VO2+), Cr2+, and Fe2+ via size-exclusion at the zeolitic channel openings, and remarkably low area specific resistance resulted from its hydrophilic surface, copious extraframework protons, and micron-scale thickness. The ZSM-5 membrane, as a new type of ion separator, demonstrated substantially reduced self-discharge rates and enhanced efficiencies for the all-vanadium and iron–chromium flow batteries as compared to the benchmark Nafion membrane. Findings of this research show that ionic microporous zeolite membranes can potentially overcome the challenge of trade-off between ion selectivity and conductivity associated with conventional polymeric ion separators.

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Section: Methodsmentioning

confidence: 99%

Proton-Selective Ion Transport in ZSM-5 Zeolite Membrane

Michos

Cao

et al. 2016

J. Phys. Chem. C

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“…13,14 For carbon felt electrodes, values of up to 1.9 × 10 −3 mAcm −2 (Tafel slope of 320 mV) have been observed. 15 Nevertheless, parasitic hydrogen evolution at the negative electrode remains an issue for the long-term operation of flow batteries relying on acidic electrolyte solutions such as iron-chromium (E 0 of Cr 2+ /Cr 3+ = −0.41 V) [16][17][18] and all-vanadium (E 0 of V 2+ /V 3+ = −0.26 V) [19][20][21] types. Mitigation strategies comprise the use of inhibitors such as lead 16,18 or bismuth, 22,23 avoiding states of charge greater than 0.85 or the use of electrolyte rebalancing devices.…”

mentioning

confidence: 99%

“…15 Nevertheless, parasitic hydrogen evolution at the negative electrode remains an issue for the long-term operation of flow batteries relying on acidic electrolyte solutions such as iron-chromium (E 0 of Cr 2+ /Cr 3+ = −0.41 V) [16][17][18] and all-vanadium (E 0 of V 2+ /V 3+ = −0.26 V) [19][20][21] types. Mitigation strategies comprise the use of inhibitors such as lead 16,18 or bismuth, 22,23 avoiding states of charge greater than 0.85 or the use of electrolyte rebalancing devices. 21,24 In the case of operation at high states of charge (SoC), parasitic hydrogen evolution exacerbates the well-known electrolyte imbalance, which is caused by solvent crossover and emerges during long-term cycling.…”

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confidence: 99%

“…For instance, early studies at Giner Inc. during electrode development for the NASA iron-chromium system reported significant variability with respect to hydrogen evolution currents between different batches of felts. 16 In a more systematic approach, the pioneering team at NASA 17,18 measured hydrogen evolution in iron-chromium flow batteries with a (fuel cell-type) rebalancing unit and found that the onset of hydrogen evolution is shifted to higher SoC and the total amount of evolved hydrogen is lowered by increasing the temperature of carbonization of the (rayon-based) carbon felts. Studies of PAN-based carbon felts in vanadium redox flow batteries point toward similar effects, since the current (coulombic) efficiency is lower when rather amorphous carbon fibers are used.…”

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confidence: 99%

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Parasitic Hydrogen Evolution at Different Carbon Fiber Electrodes in Vanadium Redox Flow Batteries

Schweiss

Pritzl

Meiser

2016

J. Electrochem. Soc.

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Carbon fiber-based fabrics such as felts, cloths or papers are porous electrode materials that are widely used in redox flow batteries. This study investigates the effect of the carbon fiber properties on hydrogen evolution at the negative electrode, which occurs as an important side reaction in redox flow batteries employing acidic electrolytes. The lowest hydrogen evolution rate was observed at carbon fibers with a high content of graphitic domains which have been subjected to surface oxidation pre-treatment. By contrast, felt materials consisting of fibers with a largely amorphous character produce elevated amounts of hydrogen during battery charging. Differences between rayon-and polyacrylonitrile (PAN)-derived carbon fibers point toward the important role of nitrogen species. © The Author(s) 2016. Published by ECS. This is an open access article distributed under the terms of the Creative Commons Attribution Non-Commercial No Derivatives 4.0 License (CC BY-NC-ND, http://creativecommons.org/licenses/by-nc-nd/4.0/), which permits non-commercial reuse, distribution, and reproduction in any medium, provided the original work is not changed in any way and is properly cited. For permission for commercial reuse, please email: oa@electrochem.org. [DOI: 10.1149/2.1281609jes] All rights reserved. Redox flow batteries are regarded as promising candidates for large-scale electrochemical storage systems for energy generated from fluctuating sources such as wind farms or photovoltaic systems.1-5 One of their widely acclaimed features is their inherent safety. Among other aspects, this is owing to the fact that the active masses consist of rather dilute, aqueous solutions of redox species (typically 1.5 to 3 molar) which are continuously circulated through an electrochemical reactor during operation. Consequently, only a small fraction of the redox species is present at any given time in the electrochemically active area, while the major part remains in electrolyte tanks, where it acts as a powerful thermal buffer.The obvious drawback of the aqueous cell chemistry is the relatively small electrochemical window, which is limited by the onset of the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER). Since common electrolytes contain strong acids with concentrations of up to 4 moles per liter in order to provide high ionic conductivity, the electrochemical window is reduced even further.Three-dimensional porous carbon electrodes such as felts, which are commonly manufactured from rayon (cellulose) or polyacrylonitrile (PAN) precursors, are well suited for these batteries since they come at a low cost, have a large surface area and exhibit sufficiently large overpotentials against hydrogen and oxygen evolution. [6][7][8][9][10][11] In the literature they are widely referred to as 'graphite' felts as they are processed at high temperatures similar to those used in the manufacturing of synthetic graphite. The fraction of crystalline domains, however, amounts to less than 50% 10 and the crystallographic d...

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Iron–Chromium Flow Battery

Zhang

Sun

2023

Flow Batteries

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Requirements for optimization of electrodes and electrolyte for the iron/chromium redox flow cell

Cited by 6 publications

References 0 publications

Proton-Selective Ion Transport in ZSM-5 Zeolite Membrane

Proton-Selective Ion Transport in ZSM-5 Zeolite Membrane

Parasitic Hydrogen Evolution at Different Carbon Fiber Electrodes in Vanadium Redox Flow Batteries

Iron–Chromium Flow Battery

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