Aqueous Organic Redox-Targeting Flow Batteries with Advanced Solid Materials: Current Status and Future Perspective

Abstract

Aqueous organic redox flow batteries (AORFBs) represent innovative and sustainable systems featuring decoupled energy capacity and power density; storing energy within organic redox-active materials. This design facilitates straightforward scalability, holding the potential for an affordable energy storage solution. However, AORFBs face challenges of unsatisfied energy density and stability. Redox-targeting (RT) reaction is a promising way to resolve these problems, which involves a closed-loop electrochemical–chemical cycle between soluble redox mediators and solid materials. Among all these systems, the aqueous organic redox-targeting system is the most promising due to its greater sustainability, safety, low cost, and excellent tunability when compared to non-aqueous or all-vanadium systems, especially when it comes to energy storage on a large scale. Firstly, various types of AORFBs and their characteristics are discussed and analyzed, followed by introducing the concept and the evolution of RT. In addition, advanced characterization techniques to analyze RT-based AORFBs are summarized. Finally, the challenges lying in aqueous organic redox-targeting flow batteries are stated and corresponding recommendations are provided. It is anticipated that AORFBs with advanced solid materials will provide a promising solution for large-scale energy storage.