Comparison of Separators vs Membranes in Nonaqueous Redox Flow Battery Electrolytes Containing Small Molecule Active Materials

Zhiming Liang, N. Harsha Attanayake, Katharine V. Greco, Bertrand J. Neyhouse, John L. Barton, Aman Preet Kaur, William L. Eubanks, Fikile R. Brushett, James Landon, Susan A. Odom

Research output: Contribution to journalArticlepeer-review

13 Scopus citations


The lack of suitable membranes for nonaqueous electrolytes limits cell capacity and cycle lifetime in organic redox flow cells. Using soluble, stable materials, we sought to compare the best performance that could be achieved with commercially available microporous separators and ion-selective membranes. We use organic species with proven stability to avoid deconvoluting capacity fade due to crossover and/or cell imbalance from materials degradation. We found a trade-off between lifetime and Coulombic efficiency: nonselective separators achieve more stable performance but suffer from low Coulombic efficiencies, while ion-selective membranes achieve high Coulombic efficiencies but experience capacity loss over time. When electrolytes are premixed prior to cycling, Coulombic efficiency remains high, but capacity is lost due to cell imbalance, which can be recovered by electrolyte rebalancing. The results of this study highlight the potential for gains in nonaqueous cell performance that may be enabled by suitable membranes.

Original languageEnglish
Pages (from-to)5443-5451
Number of pages9
JournalACS Applied Energy Materials
Issue number6
StatePublished - Jun 28 2021

Bibliographical note

Funding Information:
The Odom and Brushett groups thank the National Science Foundation for a PFI:AIR-TT award (1701085) for funding of this project. K.V.G. and B.J.N. gratefully acknowledge financial support from the National Science Foundation Graduate Research Fellowship Program under Grant No. 1122374. Any opinions, findings, or recommendations expressed in this material are those of the authors and do not necessarily reflects the views of the National Science Foundation.

Publisher Copyright:
© 2021 American Chemical Society. All rights reserved.


  • crossover
  • membrane
  • organic electrolyte
  • redox flow battery
  • separator

ASJC Scopus subject areas

  • Chemical Engineering (miscellaneous)
  • Energy Engineering and Power Technology
  • Electrochemistry
  • Electrical and Electronic Engineering
  • Materials Chemistry


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