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Updated: Dec 28, 2025

A Protocol for Electrochemical Evaluations and State of Charge Diagnostics of a Symmetric Organic Redox Flow Battery
Published on: February 13, 2017
Realization of an Asymmetric Non-Aqueous Redox Flow Battery through Molecular Design to Minimize Active Species
Anuska Shrestha1, Koen H Hendriks1, Mathew S Sigman2
1Joint Center for Energy Storage Research, Department of Chemistry, University of Michigan, 930 North University Avenue, Ann Arbor, MI 48104, USA.
Abstract:
This communication presents a mechanism-based approach to identify organic electrolytes for non-aqueous redox flow batteries (RFBs). Symmetrical flow cell cycling of a pyridinium anolyte and a cyclopropenium catholyte resulted in extensive capacity fade due to competing decomposition of the pyridinium species. Characterization of this decomposition pathway enabled the rational design of next-generation anolyte/catholyte pairs with dramatically enhanced cycling performance. Three factors were identified as critical for slowing capacity fade: (1) separating the anolyte-catholyte in an asymmetric flow cell using an anion exchange membrane (AEM); (2) moving from monomeric to oligomeric electrolytes to limit crossover through the AEM; and (3) removing the basic carbonyl moiety from the anolyte to slow the protonation-induced decomposition pathway. Ultimately, these modifications led to a novel anolyte-catholyte pair that can be cycled in an AEM-separated asymmetric RFB for 96 h with >95 % capacity retention at an open circuit voltage of 1.57 V.
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