Solvation regulation to mitigate the decomposition of 2, 6-dihydroxyanthraquinone in aqueous organic redox flow batteries. Issue 2 (11th January 2023)

• Record Type: Journal Article
• Authors: Peng, Kang; Li, Yuanyuan; Tang, Gonggen; Liu, Yahua; Yang, Zhengjin; Xu, Tongwen
• Is Part Of: Energy & environmental science. Volume 16:Issue 2(2023)
• Page Start: 430
• Page End: 437
• Publication Date: 2023-01-11
• Subjects: Energy conversion -- Periodicals; Fuel switching -- Periodicals; Environmental sciences -- Periodicals; Environmental chemistry -- Periodicals; 333.79
• DOI: 10.1039/d2ee03617g
• Languages: English
• ISSNs: 1754-5692

Abstract

Abstract : This communication documents the first case of a solvation regulation strategy for improving the AORFB cycling lifetime by exploiting the ion pairing and hydration effect of supporting electrolytes. 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 DHAQ 2− /DHAHQ 4− anions, thereby deactivating the chemical or electrochemical reduction of DHAHQ 4− 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/K4 Fe(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.