Evaluation of carbon felts functionalized with deep eutectic solvents as electrodes for all-vanadium redox flow batteries Mauricio Murillo Queen Mary University of London, UK All-vanadium redox flow batteries are promising large-scale energy storage solutions to support intermittent power generation[1]. Commercial carbon felts are among the most commonly used electrodes alongside this electrolyte due to their high conductivities and surface areas, however these materials exhibit poor wettability and electrochemical activity towards vanadium redox reactions, which produces overpotentials and with this, lower efficiencies[2]. A strategy to overcome this limitation is through chemical modification of the felt surface by introduction of electronegative oxygen- or nitrogen-based functional groups, by etching of the fibers or deposition of transition metals[2-6]. In this project, graphite felts were treated with choline chloride-based deep eutectic solvents and an iron-based eutectic mixture through soonication or heating. The impact of these treatments on the fibers was evaluated by XPS, SEM and Raman spectroscopy. The electrochemical activity of the felts was evaluated in a three-electrode cell and in full-cell mode through CV, EIS and battery metrics such as galvanostatic cycling and polarization analysis. Preliminary results of the modified carbon felts showed higher current peaks compared to pristine felts and less overpotential for the oxidation of V(IV) to V(V). References 1. K. Lin, Q. Chen, M. R. Gerhardt, L. Tong, S. Bok, S. B. Kim, L. Eisenach, A. W. Valle, D. Hardee, R. G. Gordon, M. J. Aziz and M. P.Marshak, Science, 2015, 349, 1529–1532. 2. C.-H. Lin, Y.-D. Zhuang, D.-G. Tsai, H.-J. Wei and T.-Y. Liu, Polymers , 2020, 12 , 1372. 3. Duan, B. Li, D. Lu, W. Xiaoliang, Z. Nie, V. Murugesan, J. P. Kizewski, A. Hollas, D. Reed, V. Sprenkle and W. Wang, Journal of Energy Chemistry , 2018, 27 , 1381-1385. 4. M. W. Thielke, G. Tian and A. Jorge Sobrido, Journal of Physics: Materials , 2022, 5 , 024004. 5. M. C. Ribadeneyra, L. Grogan, H. Au, P. Schlee, S. Herou, T. Neville, P. L. Cullen, M. D. R. Kok, O. Hosseinaei, S. Danielsson, P. Tomani, M. M. Titirici, D. J. L. Brett, P. R. Shearing, R. Jervis and A. B. Jorge, Carbon , 2020, 157 , 847-856. 6. K. J. Kim, H. S. Lee, J. Kim, M.-S. Park, J. H. Kim, Y.-J. Kim and M. Skyllas-Kazacos, ChemSusChem , 2016, 9 , 1329-1338.
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