Issue 2, 2023

Solvation regulation to mitigate the decomposition of 2,6-dihydroxyanthraquinone in aqueous organic redox flow batteries

Abstract

In the development of aqueous organic redox flow batteries (AORFBs), anthraquinone derivatives (AQs) attract a great deal of attention as the most promising negative electrolytes. The molecular structures of AQs have been engineered to maintain their long-term stability in aqueous media, which, however, requires tedious syntheses and multi-step purifications. Herein, we document the first case of a solvation regulation strategy to extend the lifetime of 2,6-dihydroxyanthraquinone (DHAQ) electrolytes, i.e., incorporating tetramethylammonium cations (TMA+) in the supporting electrolytes to interfere with the solvation structure of DHAQ2−/DHAHQ4− anions, thereby deactivating the chemical or electrochemical reduction of DHAHQ4− that initiates the subsequent side reactions. The ion pairing and hydration effect of TMA+ are elaborately demonstrated through experiments and simulations. The capacity fade rate of DHAQ/K4Fe(CN)6 cells caused by 0.1 M DHAQ electrolyte decomposition decreases by almost an order of magnitude, from 5.34% per day without TMA+ to 0.65% per day with 4.5 M TMA+. This strategy is effective when the DHAQ concentration is raised to 0.4 M. We anticipate that this mitigation strategy will readily extend to other organic redox-active molecules.

Graphical abstract: Solvation regulation to mitigate the decomposition of 2,6-dihydroxyanthraquinone in aqueous organic redox flow batteries

Supplementary files

Article information

Article type
Communication
Submitted
08 Nov 2022
Accepted
23 Dec 2022
First published
26 Dec 2022

Energy Environ. Sci., 2023,16, 430-437

Solvation regulation to mitigate the decomposition of 2,6-dihydroxyanthraquinone in aqueous organic redox flow batteries

K. Peng, Y. Li, G. Tang, Y. Liu, Z. Yang and T. Xu, Energy Environ. Sci., 2023, 16, 430 DOI: 10.1039/D2EE03617G

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