Investigating the Iron Plating and Stripping of Anolytes for All-Iron Redox-Flow Batteries

Marius Engler (), Michael Stich, Christoph Baumer and Andreas Bund
Additional contact information
Marius Engler: Electrochemistry and Electroplating Group, Institute of Materials Science and Engineering, Technische Universität Ilmenau, 98693 Ilmenau, Germany
Michael Stich: Electrochemistry and Electroplating Group, Institute of Materials Science and Engineering, Technische Universität Ilmenau, 98693 Ilmenau, Germany
Christoph Baumer: Electrochemistry and Electroplating Group, Institute of Materials Science and Engineering, Technische Universität Ilmenau, 98693 Ilmenau, Germany
Andreas Bund: Electrochemistry and Electroplating Group, Institute of Materials Science and Engineering, Technische Universität Ilmenau, 98693 Ilmenau, Germany

J, 2024, vol. 7, issue 4, 1-13

Abstract: All-iron redox-flow batteries (AIRFB) are capable of addressing the needs for cost-effective long-term storage of renewable energies. Currently, a major limitation of AIRFB performance is the half-cell reaction of the anolyte utilising the redox couple Fe/Fe 2+ . In this work, the performance of sulphate and chloride-based iron electrolytes was investigated by combining cyclic voltammetry (CV) and electrochemical quartz crystal microbalance (EQCM). The investigations demonstrate that complexing agents exert a detrimental influence on the kinetics of plating/stripping reactions, resulting in diffusivity reduction, while favouring hydrogen evolution reaction (HER). The coulombic (plating) efficiency was found to be 87.1% at −1.2 V vs. Ag/AgCl (sat’d) at pH 3.5, while the coulombic efficiency in oxidation sweep (stripping) was observed to be 100% in an electrolyte containing 0.8 M FeCl 2 and 3 M NH 4 Cl. In the context of iron deposition, the most crucial factors are the suppression of HER, and the influence of diffusion limitations, as well as the role of additives in this process to achieve a high reversibility. It is evident that the investigated complexing agents of glycine, malic acid and malonic acid are inadequate for battery-compatible, efficient properties, given that the overvoltages for the charge transfer reaction are too high and parasitic HER reduces coulombic efficiencies. Ultimately, the choice of deposition parameters from EQCM and electrolyte composition reduced to 0.8 M FeCl 2 , and 3 M NH 4 Cl can optimise the battery efficiencies as such.

Keywords: all-iron redox-flow batteries; stationary energy storage; iron plating; iron stripping; electrochemical quartz crystal microbalance; cyclic voltammetry (search for similar items in EconPapers)
JEL-codes: I1 I10 I12 I13 I14 I18 I19 (search for similar items in EconPapers)
Date: 2024
References: View complete reference list from CitEc
Citations:

Downloads: (external link)
https://www.mdpi.com/2571-8800/7/4/34/pdf (application/pdf)
https://www.mdpi.com/2571-8800/7/4/34/ (text/html)

Related works:
This item may be available elsewhere in EconPapers: Search for items with the same title.

Export reference: BibTeX RIS (EndNote, ProCite, RefMan) HTML/Text

Persistent link: https://EconPapers.repec.org/RePEc:gam:jjopen:v:7:y:2024:i:4:p:34-583:d:1541573

Access Statistics for this article

J is currently edited by Ms. Angelia Su

More articles in J from MDPI
Bibliographic data for series maintained by MDPI Indexing Manager ().