Near Neutral pH Redox Flow Battery with Low Permeability and Long-Lifetime Phosphonated Viologen Active Species
- Harvard Univ., Cambridge, MA (United States). John A. Paulson School of Engineering and Applied Sciences
- Harvard Univ., Cambridge, MA (United States)
A highly stable phosphonate-functionalized viologen is introduced in this work as the redox-active material in a negative potential electrolyte for aqueous redox flow batteries (ARFBs) operating at nearly neutral pH. The solubility is 1.23 m and the reduction potential is the lowest of any substituted viologen utilized in a flow battery, reaching –0.462 V versus SHE at pH = 9. The negative charges in both the oxidized and the reduced states of 1,1'-bis(3-phosphonopropyl)-[4,4'-bipyridine]-1,1'-diium dibromide (BPP–Vi ) effect low permeability in cation exchange membranes and suppress a bimolecular mechanism of viologen decomposition. A flow battery pairing BPP–Vi with a ferrocyanide-based positive potential electrolyte across an inexpensive, non-fluorinated cation exchange membrane at pH = 9 exhibits an open-circuit voltage of 0.9 V and a capacity fade rate of 0.016% per day or 0.00069% per cycle. Overcharging leads to viologen decomposition, causing irreversible capacity fade. Our research introduces extremely stable, extremely low-permeating and low reduction potential redox active materials into near neutral ARFBs.
- Research Organization:
- Pacific Northwest National Laboratory (PNNL), Richland, WA (United States); Harvard Univ., Cambridge, MA (United States)
- Sponsoring Organization:
- USDOE; National Science Foundation (NSF)
- Contributing Organization:
- Massachusetts Clean Energy Center
- Grant/Contract Number:
- AC05-76RL01830; CBET‐1914543; 428977
- OSTI ID:
- 1608418
- Alternate ID(s):
- OSTI ID: 1608377
- Journal Information:
- Advanced Energy Materials, Vol. 10, Issue 20; ISSN 1614-6832
- Publisher:
- WileyCopyright Statement
- Country of Publication:
- United States
- Language:
- English
Web of Science
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