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Ertan Agar1 Patrick Cappillino2

1, University of Massachusetts, Lowell, Lowell, Massachusetts, United States
2, University of Massachusetts Dartmouth, Dartmouth, Massachusetts, United States

Redox flow batteries (RFBs) are a promising large-scale energy storage technology forintegration of intermittent renewable sources, such as wind and solar, into the electrical grid.Among several types of RFBs under development, non-aqueous redox flow batteries (NRFBs) have recently gained significant interest due to their wide electrochemical potential windows and improved range of operating temperature, offering high performance operation compared to their aqueous counterparts [1]. Despite the promise of NRFBs, state-of-the-art systems are limited by decomposition of active materials, often exhibiting nearly quantitative capacity-fade after only modest cycling [2-3]. This underscores a critical challenge currently limiting the advancement of this technology – stability. To address the instability issues of these systems, we demonstrate a fundamentally new design strategy for NRFB active materials. This approach leverages millions of generations of biological evolution as a toolkit to elucidate molecules that provide a stable scaffold for further development. The compounds investigated in this study are based on chelators that have evolved as part of biological metal-transport systems [4]. As a result of natural-selection they exhibit extremely strong metal-binding properties, shutting down decomposition pathways. In this presentation, we will demonstrate the performance characteristics of the proposed NRFB system using charge/discharge cycling, capacity fade and efficiency analyses. Using in-situ spectroscopic analysis, we demonstrate chemical stability during cycling and tight coupling between current and electrochemical formation of the oxidized and reduced form of the active material. Additionally, recent progress to reduce area specific resistance and improve current
density applied during operation will be discussed.
References:
1. K. Gong, Q. Fang, S. Gu, S. F. Y. Li, Y. Yan, Energy Environ. Sci., 2015, 8 (12), 3515-3530.
2. X. Wei, W. Xu, J. Huang, L. Zhang, E. Walter, C. Lawrence, M. Vijayakumar, W. A. Henderson, T.
Liu, L. Cosimbescu, B. Li, V. Sprenkle and W. Wang, Angew Chem Int Ed Engl, 2015, 54, 8684-8687.
3. I. L. Escalante-García, J. S. Wainright, L. T. Thompson and R. F. Savinell, J. Electrochem. Soc., 2015,
162, A363-A372.
4. H. Huang, R. Howland, E. Agar, M. Nourani, J. A. Golden, P. J. Cappillino, J. Mater. Chem. A., 2017,
5, 11586-11591.

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