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Abstract Redox flow batteries (RFB) have emerged as one of the most promising technologies for large‐scale energy storage owing to their high safety, long operation life, and decoupled design of energy and power. However, the problems of high cost and low energy density restrict their further development. The cost merit and tunable structure of organic redox‐active materials have prompted the development of organic RFBs. The solubility of the redoxmer is recognized as a parameter that contributes directly to the energy density. Herein, we focus on strategies for enhancing the solubility of organic redoxmers in aqueous RFBs. The effects of incorporating different hydrophilic functional groups on the solubility of the redoxmer and its effect on the performance of other batteries are systematically and exhaustively described. Other strategies, such as molecular symmetry tuning and employing more soluble counterions and cosolvents, are also summarized. The development trends and prospects for organic RFBs are also discussed.
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This content will become publicly available on November 7, 2025
Modern organophotocatalysts: a new inspiration source for Symmetrical Organic Redox Flow Batteries
Redox flow batteries (RFBs) have emerged as significant energy storage systems amid the growing adoption of renewable energy. However, the advancement of all-organic RFBs is hindered by material crossover, limited energy density, and the time-consuming selection of suitable electrolyte partners. To address these challenges, bipolar redox-active organic molecules (BRMs) show promise for charge storage in symmetric organic redox flow batteries (SORFBs), although their development can be complex and tedious. In this study, we report an approach aimed at streamlining the identification of suitable compounds through an examination of the organophotocatalyst literature, illustrated through six acridinium compounds exhibiting stable redox states. These compounds were thoroughly characterized in electrochemical cells and subjected to cycling tests in fully symmetric flow batteries. Notably, a trisubstituted electron-rich acridinium compound emerged as a potential candidate, demonstrating over 20 days of cycling stability. Given the extensive library of organic catalysts and the advantages of SORFB designs, this approach will prove to be essential for developing an innovative electrochemical storage system.
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- Award ID(s):
- 2102034
- PAR ID:
- 10631428
- Publisher / Repository:
- ChemXriv
- Date Published:
- Format(s):
- Medium: X
- Institution:
- University of Arizona
- Sponsoring Org:
- National Science Foundation
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