Vitamin-Based Organic Electrolytes for Redox Flow Batteries

With the current drive towards environmental sustainability, electrochemical energy storage system (EES) such as redox flow batteries (RFB) are thought to be a promising solution as they can play an important role in balancing energy generation and consumption to ensure power network stability and reliability. [1,2] Organic compounds possess tremendous potential for energy storage as they are structural diverse and synthetically tunable. In addition, organic compounds can be cost-effective and environmentally benign due to their abundancy in nature. However, many organic species experience stability issue in their charged form. [3,4] The present study reports an all-organic vitamin-based molecular system based on a non-aqueous, mixed-reactant electrolyte containing modified forms of the naturally occurring vitamin K 1 and vitamin E as anolyte and catholyte, respectively. [5,6] In the presence of malonic ester (a relatively weak organic acid), the redox transformations of the organic species were proven chemically stable and reversible under exhaustive electrolysis conditions, as confirmed by UV-vis spectroscopy. [7] The pairing of both half-cells provides a desirable experimental cell voltage of 1.27 V. The proposed system also demonstrates good thermal and ambient stability via series of experiments. The overall findings presented demonstrate the practical significance of the vitamin-based organic electrolytes in the all-organic RFB technologies. References 1. S. H. Shin, S. H. Yun and S. H. Moon, RSC Adv, (3) 2013 , 9095-9116. 2. X. Luo, J. Wang, M. Dooner and J. Clarke, Appl. Energy , (137) 2015 , 511-536. 3. X. Wei, X. L.; Xu, W.; Huang, J. H.; Zhang, L; Walter, E.; Lawrence, C.; Vijayakumar, M.; Henderson, W. A.; Liu, T. B.; Cosimbescu, L.; Li, B.; Sprenkle, V; Wang, W. Chem. Int. Ed. 2015 , 54 , 8684 –8687. 4. X. Wei, X. L.; Pan, W. X.; Duan, W. T.; Hollas, A.; Yang, Z.; Li, B.; Nie, Z. M.; Liu, J.; Reed, D.; Wang, W.; Sprenkle, V. L. ACS Energy Lett . 2017 , 2 (9), 2187-2204. 5. Y. L. Hui, E. L. K. Chng, Y. L. C. Chng, H. L. Poh and R. D. Webster, J. Am. Chem. Soc, (131) 2009 , 1523-1534. 6. H. M. Peng, B. F. Choules, W. W. Yao, Z. Zhang, R. D. Webster and P. M. Gill, J. Phys. Chem B, (112) 2008 , 10367–10374. 7. R. R. S. Shi, M. E. Tessensohn, S. J. L. Lauw, N. A. B. Y. Foo and R. D. Webster, Chem. Commun , (55) 2019 , 2277.