Zwitterionic Ferrocenes: An Approach for Redox Flow Battery (RFB) Catholytes

Baosen Zhang, Briana R. Schrage, Ariana Frkonja-Kuczin, Sanjay Gaire, Ivan A. Popov, Christopher J. Ziegler, Aliaksei Boika

Research output: Contribution to journalArticlepeer-review

8 Scopus citations

Abstract

Herein we present two new ferrocene compounds Fc3 and Fc4 with, respectively, propyl and butyl zwitterionic side chains. These compounds are highly soluble in water (0.66 M for Fc3 and 2.01 M for Fc4). When paired with anthraquinone-2,7-disulfonate as the anolyte, these zwitterionic ferrocenes exhibit excellent performance under neutral aqueous conditions. Voltage and energy efficiencies were ca. 88%, and the Coulombic efficiency was over 99% for both high-concentration redox flow batteries. We observed a difference in stability between the lengths of the zwitterionic chains, with Fc4 showing higher stability than Fc3, and the capacity decreased by ∼5% at the end of 20 cycles (∼1% per day). Density functional theory calculations revealed striking differences in the conformational properties between Fc3 and Fc4, with Fc4 retaining a linear structure of the side chain in solution, while Fc3 favored both linear and curved geometries.

Original languageEnglish
Pages (from-to)8117-8120
Number of pages4
JournalInorganic Chemistry
Volume61
Issue number21
DOIs
StatePublished - May 30 2022
Externally publishedYes

Funding

The authors thank Dr. Z. Zhao (Institute for Bioscience & Biotechnology Research, University of Maryland, College Park) for helpful discussions. I.A.P. acknowledges the computational resources at the Ohio Supercomputer Center and the ARCC HPC cluster at the University of Akron. The authors are grateful to the University of Akron and the National Science Foundation (CHE-1665267) for support of this research.

FundersFunder number
National Science FoundationCHE-1665267
University of Akron

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