Flow Battery Molecular Reactant Stability Determined by Symmetric Cell Cycling Methods
We present an unbalanced compositionally-symmetric flow cell method for revealing and quantifying different mechanisms for capacity fade in redox flow batteries that are based on molecular energy storage. We utilize it, accompanied in some cases by a corresponding static-cell cycling method, to study capacity fade in cells comprising anthraquinone di-sulfonate, di-hydroxy anthraquinone, iron hexacyanide, methyl viologen, and bis-trimethylammoniopropyl viologen. In all cases the cycling capacity decay is reasonably consistent with exponential in time and is independent of the number of charge-discharge cycles imposed. By introducing pauses at various states of charge of the capacity-limiting side during cycling, we show that in some cases the temporal fade time constant is dependent on the state of charge. These observations suggest that molecular lifetime is dominated by chemical rather than electrochemical mechanisms. These mechanisms include irrecoverable chemical decomposition and recoverable interactions with cell materials. We conclude with recommendations for cell cycling protocols for evaluating stability of single electrolytes.
- Research Organization:
- United Technologies Corp., East Hartford, CT (United States)
- Sponsoring Organization:
- USDOE Advanced Research Projects Agency - Energy (ARPA-E)
- Grant/Contract Number:
- AR0000767
- OSTI ID:
- 1437213
- Alternate ID(s):
- OSTI ID: 1510072
- Journal Information:
- Journal of the Electrochemical Society, Vol. 165, Issue 7; ISSN 0013-4651
- Publisher:
- The Electrochemical SocietyCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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