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A Phosphonate‐Functionalized Quinone Redox Flow Battery at Near‐Neutral pH with Record Capacity Retention Rate
Author(s) -
Ji Yunlong,
Goulet MarcAntoni,
Pollack Daniel A.,
Kwabi David G.,
Jin Shijian,
Porcellinis Diana,
Kerr Emily F.,
Gordon Roy G.,
Aziz Michael J.
Publication year - 2019
Publication title -
advanced energy materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.08
H-Index - 220
eISSN - 1614-6840
pISSN - 1614-6832
DOI - 10.1002/aenm.201900039
Subject(s) - flow battery , redox , phosphonate , electrolyte , aqueous solution , materials science , solubility , inorganic chemistry , electrochemistry , chemical engineering , chemistry , electrode , organic chemistry , engineering
A highly stable phosphonate‐functionalized anthraquinone is introduced as the redox‐active material in a negative potential electrolyte (negolyte) for aqueous redox flow batteries operating at nearly neutral pH. The design and synthesis of 2,6‐DPPEAQ, (((9,10‐dioxo‐9,10‐dihydroanthracene‐2,6‐diyl)bis(oxy))bis(propane‐3,1‐diyl))bis(phosphonic acid), which has a high solubility at pH 9 and above, is described. Chemical stability studies demonstrate high stability at both pH 9 and 12. By pairing 2,6‐DPPEAQ with a potassium ferri/ferrocyanide positive electrolyte across an inexpensive, nonfluorinated permselective polymer membrane, this near‐neutral quinone flow battery exhibits an open‐circuit voltage of 1.0 V and a capacity fade rate of 0.00036% per cycle and 0.014% per day, which is the lowest ever reported for any flow battery in the absence of rebalancing processes. It is further demonstrated that the negolyte pH drifts upward upon atmospheric oxygen penetration but, when oxygen is excluded, oscillates reversibly between 9 and 12 during cycling. These results enhance the suitability of aqueous‐soluble redox‐active organics for use in large‐scale energy storage, potentially enabling massive penetration of intermittent renewable electricity.