Michael Aziz1
Harvard University1
<br/>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. Wide-scale utilization of flow batteries is limited by the cost of 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. [1-6]. These redox active materials can be inexpensive and exhibit rapid redox kinetics and high solubilities, potentially enabling massive electrical energy storage at greatly reduced cost. We have developed protocols for measuring capacity fade rates, which are particularly important for establishing very low capacity fade rates, and have discovered that the capacity fade rate is determined by the molecular calendar life, which can depend on state of charge, but is independent of the number of charge-discharge cycles imposed [7,8]. We will report the performance of some of the very few chemistries with long enough calendar life for practical application in stationary storage [8], and on progress in reversing capacity fade by recomposing decomposed molecules [9].<br/> <br/>[1] B. Huskinson, M.P. Marshak, C. Suh, S. Er, M.R. Gerhardt, C.J. Galvin, X. Chen, A. Aspuru-Guzik, R.G. Gordon and M.J. Aziz, "A metal-free organic-inorganic aqueous flow battery", <i>Nature</i> <b>505</b>, 195 (2014), http://dx.doi.org/10.1038/nature12909<br/> <br/>[2] K. Lin, Q. Chen, M.R. Gerhardt, L. Tong, S.B. Kim, L. Eisenach, A.W. Valle, D. Hardee, R.G. Gordon, M.J. Aziz and M.P. Marshak, "Alkaline Quinone Flow Battery", <i>Science</i> <b>349</b>, 1529 (2015), http://dx.doi.org/10.1126/science.aab3033<br/> <br/>[3] 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", <i>ACS Energy Letters</i> <b>2</b>, 639 (2017). http://dx.doi.org/10.1021/acsenergylett.7b00019<br/> <br/>[4] 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” <i>Joule</i> <b>2</b>, 1907 (2018). https://doi.org/10.1016/j.joule.2018.07.005<br/> <br/>[5] Y. Jing, M. Wu, A.A. Wong, E.M. Fell, S. Jin, D.A. Pollack, E.F. Kerr, R.G. Gordon and M.J. Aziz, “In situ Electrosynthesis of Anthraquinone Electrolytes in Aqueous Flow Batteries”, <i>Green Chemistry,</i> <b>22</b>, 6084 (2020); https://doi.org/10.1039/D0GC02236E <br/> <br/>[6] M. Wu, M. Bahari, E.M. Fell, R.G. Gordon and M.J. Aziz, “High-performance anthraquinone with potentially low cost for aqueous redox flow batteries” <i>J. Mater. Chem. A</i> <b>9</b>, 26709-26716 (2021). https://doi.org/10.1039/D1TA08900E <br/> <br/>[7] M.-A. Goulet & M.J. Aziz, “Flow Battery Molecular Reactant Stability Determined by Symmetric Cell Cycling Methods”, <i>J. Electrochem. Soc.</i> <b>165</b>, A1466 (2018). http://dx.doi.org/10.1149/2.0891807jes <br/> <br/>[8] D.G. Kwabi, Y.L. Ji and M.J. Aziz, “Electrolyte Lifetime in Aqueous Organic Redox Flow Batteries: A Critical Review” <i>Chem. Rev.</i> <b>120</b>, 6467 (2020); https://doi.org/10.1021/acs.chemrev.9b00599 <br/> <br/>[9] Y. Jing, E.W. Zhao, M.-A. Goulet, M. Bahari, E. Fell, S. Jin, A. Davoodi, Erlendur Jónsson, M. Wu, C.P. Grey, R.G. Gordon and M.J. Aziz, “In-situ Electrochemical Recomposition of Decomposed Redox-active Species in Aqueous Organic Flow Batteries” <i>Nature Chemistry</i> <b>14</b>, in press (2022). https://doi.org/10.1038/s41557-022-00967-4 ; http://dx.doi.org/10.33774/chemrxiv-2021-x05x1