(Invited) Recent Progress in Organic-Based Aqueous Flow Batteries
Authors: Aziz Michael J. 
Published: February 2020

The ability to store large amounts of electrical energy is of increasing importance with the growing fraction of electricity generation from intermittent renewable sources such as wind and solar. Flow batteries show promise because the designer can independently scale the power (electrode area) and energy (arbitrarily large storage volume) components of the system by maintaining all electro-active species in fluids. Wide-scale utilization of flow batteries is limited by the abundance and cost of these materials, particularly those utilizing redox-active metals such as vanadium or precious metal electrocatalysts. We have developed high performance flow batteries based on the aqueous redox behavior of small organic and organometallic molecules, e.g. [1-10]. These redox active materials can be inexpensive and exhibit rapid redox kinetics and long lifetimes, although short lifetimes are more common [7]. We have developed new protocols for measuring capacity fade rates and have discovered that the capacity fade rate is typically determined by the molecular calendar life, which can depend on state of charge, but is independent of the number of charge-discharge cycles imposed [7]. We will report the performance of the few chemistries with long enough calendar life, or the potential for acquiring long enough calendar life [9], for practical application in stationary storage.
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1, 16102 (2016). http://dx.doi.org/10.1038/nenergy.2016.102
[4] E.S. Beh, D. De Porcellinis, R.L. Gracia, K.T. Xia, R.G. Gordon and M.J. Aziz, "A Neutral pH Aqueous Organic/Organometallic Redox Flow Battery with Extremely High Capacity Retention", ACS Energy Letters
2, 639 (2017). http://dx.doi.org/10.1021/acsenergylett.7b00019
[5] Z. Yang, L. Tong, D.P. Tabor, E.S. Beh, M.-A. Goulet, D. De Porcellinis, A. Aspuru-Guzik, R.G. Gordon, and M.J. Aziz, "Alkaline benzoquinone aqueous flow battery for large-scale storage of electrical energy” Advanced Energy Materials
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[6] D.G. Kwabi, K. Lin, Y. Ji, E.F. Kerr, M.-A. Goulet, D. DePorcellinis, D.P. Tabor, D.A. Pollack, A. Aspuru-Guzik, R.G. Gordon, and M.J. Aziz, “Alkaline Quinone Flow Battery with Long Lifetime at pH 12” Joule
2, 1907 (2018). https://doi.org/10.1016/j.joule.2018.07.005
[7] M.-A. Goulet & M.J. Aziz, “Flow Battery Molecular Reactant Stability Determined by Symmetric Cell Cycling Methods”, J. Electrochem. Soc.
165, A1466 (2018). http://dx.doi.org/10.1149/2.0891807jes
[8] Y. Ji, M.-A. Goulet, D.A. Pollack, D.G. Kwabi, S. Jin, D. DePorcellinis, E.F. Kerr, R.G. Gordon, and M.J. Aziz, “A phosphonate-functionalized quinone redox flow battery at near-neutral pH with record capacity retention rate” Advanced Energy Materials
2019 1900039; https://doi.org/10.1002/aenm.201900039
[9] M.-A. Goulet, L. Tong, D.A. Pollack, D.P. Tabor, E.E. Kwan, A. Aspuru-Guzik, R.G. Gordon, and M.J. Aziz, “Extending the lifetime of organic flow batteries via redox state management” Journal of the American Chemical Society
141, in press (2019); https://doi.org/10.1021/jacs.8b13295
[10] http://aziz.seas.harvard.edu/electrochemistry