Using on-line NMR spectroscopy to understand crossover in redox flow batteries Emma Latchem 1 , Thomas Kress 1 , Peter A. A.Klusener 3 , R. Vasant Kumar 2, Alexander C.Forse 1 1 University of Cambridge, UK, 2 Department of Materials Science, University of Cambridge, UK, 3 Shell Global Solutions International B.V., Energy Transition Campus Amsterdam, Netherlands Tackling the climate crisis requires huge increases in renewable power generation from wind and solar. 1 There is an urgent requirement for new technologies that can store this intermittent energy affordably. 2 Aqueous organic redox-flow batteries (AORFBs) are promising candidates for this application, as they are scalable and can be made from low-cost, Earth-abundant material. However, the lifetime of these batteries is limited by crossover- driven capacity fade. 3-4 “Crossover” describes the unwanted transport of redox-active components through the membrane. Traditional membrane permeability measurements only account for diffusional crossover, and do not capture all contributions to membrane transport in working batteries, including migration. Inspired by previous studies, 5 we developed a new method for characterising crossover in operating aqueous organic redox-flow batteries, using on-line quantitative 1 H NMR spectroscopy. Using the 2,6-dihydroxyantharquinone/ ferrocyanide battery as a model, we observed a doubling of 2,6-dihydroxyantharquinone crossover rates during battery charging, which we believe is due to additional transport by migration. These measurements allow us to differentiate how different transport mechanisms contribute to crossover and identify which charging protocols are optimized to minimise this process. Furthermore, our new method has enabled us to gain insight into how crossover contributes to capacity loss within the battery. This improved understanding of crossover-driven capacity loss will facilitate the development of the superior materials and charging protocols needed for longer- lasting batteries. References 1. IPCC, 2022: Summary for Policymakers. In: Climate Change 2022: Mitigation of Climate Change. Contribution of Working Group III to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change [P.R. Shukla, J. Skea, R. Slade, A. Al Khourdajie, R. van Diemen, D. McCollum, M. Pathak, S. Some, P. Vyas, R. Fradera, M. Belkacemi, A. Hasija, G. Lisboa, S. Luz, J. Malley, (eds.)]. Cambridge University Press, Cambridge, UK and New York, NY, USA. doi: 10.1017/9781009157926.001 2. J.Rugolo and M. J. Aziz, Energy Environ. Sci. , 2012, 5 , 7151. R. Darling, K. Gallagher, W. Xie, L. Su and F. Brushett, J. Electrochem. Soc ., 2016, 163 , A5029–A5040. 3. R. Tan, A. Wang, R. Malpass-Evans, R. Williams, E. W. Zhao, T. Liu, C. Ye, X. Zhou, B. P. Darwich, Z. Fan, L. Turcani, E. Jackson, L. Chen, S. Y. Chong, T. Li, K. E. Jelfs, A. I. Cooper, N. P. Brandon, C. P. Grey, N. B. McKeown and Q. Song, Nat. Mater ., 2020, 19 , 195–202. E. W. Zhao, T. Liu, E. Jónsson, J. Lee, I. Temprano, R. B. Jethwa, A. Wang, H. Smith, J. Carretero-González, Q. Song and C. P. Grey, Nature , 2020, 579 , 224–228.
P05
© The Author(s), 2023
Made with FlippingBook Learn more on our blog