Prof. Robert Savinell has made many important contributions to fuel-cell and flow-battery systems. Both of these systems utilize electrochemical flow cells to either generate or store electricity. Because of this commonality, one can leverage concepts used in one for adoption in the other. An important topic for any electrochemical system is durability. A considerable amount of work has been on this topic with polymer-electrolyte fuel cells (PEFCs); in fact, a textbook devoted to this topic was published over a decade ago [1]. However, despite a recent renaissance in redox-flow-battery (RFB) technologies, assessing the durability of RFB cells is a topic that has not received much attention in the open literature, to date, and further research is needed to better understand dominant degradation mechanisms [2, 3].

A simple and fast diagnostic tool has been developed for analyzing polymer-electrolyte fuel-cell degradation [4, 5]. The tool is based on analyzing changes in polarization curves of a cell over its lifetime. Using the polarization-change curve methodology, the primary mechanism for degradation (kinetic, ohmic, and/or transport related) can be identified. This technique can also be applied to RFB cells, which will be the focus of this presentation. This diagnostic tool provides a simple method for rapid determination of primary degradation mechanisms. Areas for more detailed future investigations shall also be summarized.

References

1. Modern Topics in Polymer Electrolyte Fuel Cell Degradation, Mench, M.; Kumbur, E.; and Veziroglu, T.; Editors; Elsevier, Denmark (2011).
2. Yuan, X.-Z.; Song, C.; Platt, A.; Zhao, N.; Wang, H.; Li, H.; Fatih, K.; Jang, D.; “A review of all-vanadium redox flow battery durability: Degradation mechanisms and mitigation strategies,” J. Energy Res., 43 (2019) 6599−6638.
3. Yao, Y.; Lei, J.; Shi, Y.; Ai, F.; Lu, Y. C.; “Assessment methods and performance metrics for redox flow batteries,” Energy, 6 (2021) 582−588.
4. L. Perry, R. Balliet, and R. Darling, “Experimental Diagnostics and Durability Testing Protocols,” a chapter in [1].
5. M. Pant, Z. Yang, M. L. Perry, and A. Z. Weber, “Development of a Simple and Rapid Diagnostic Method for Polymer-Electrolyte Fuel Cells,” J. Electrochem. Soc., 165 (2018) F3007.