Quinones for Aqueous Organic Redox Flow Battery: A Prospective on Redox Potential, Solubility, and Stability

Abstract

In recent years, there has been considerable interest in the potential of quinones as a promising category of electroactive species for use in aqueous organic redox flow batteries. These materials offer tunable properties and the ability to function as both positive and negative electrolytes, making them highly versatile and suitable for a range of applications. Ongoing research has focused on improving the stability, solubility, and performance of quinones, with a particular emphasis on the creation of stable negolytes. The pairing of these advancements with alternate chemistries has created new prospects for commercial applications. However, challenges persist regarding the stability of quinones in high‐potential electrolytes and the limited number of viable quinones available. Despite these obstacles, significant strides have been made, and the potential for quinones to revolutionize energy storage technology is vast. This review article provides a comprehensive overview of recent progress in this area, with a specific focus on redox potential, solubility, and stability, and offers valuable insights into the future of quinone‐based aqueous organic redox flow batteries.

Stabilization of Naphthalene Diimide Anions by Ion Pair Formation in Nonaqueous Organic Redox Flow Batteries

“…Redox flow batteries (RFBs) have emerged as a promising solution for the cost-effective and safe storage of electrical energy at grid-scale levels. , The operational simplicity and scalability make them attractive for efficient technical implementation, significantly reducing the need for extensive maintenance. , A critical factor in achieving their potential lies in the selection of an appropriate charge carrier molecule. In principle, organic molecules offer a wide range of physicochemical and electrochemical properties, including solubility, redox potential, and redox stability, which can be tailored by modifying molecular structures and incorporating functional groups. − However, several challenges must be addressed when organic molecules are utilized as charge carriers in RFBs. These challenges encompass synthetic access to sufficient quantities, maintaining redox stability and achieving high storage capacity …”

“…This was accompanied by the emergence of ν 2 ′ and ν nap ′ bands, although their signals appeared below 1550 cm −1 and were somewhat obscured by the notable background signals originating from the MeCN solvent (Figure S9). Furthermore, our investigation employed 7 Li NMR spectra to scrutinize the behavior of Li + ions within the system more specifically. The spectra revealed a distinct transition: a sharp Li + signal, observed in CD 3 CN, gradually broadened and shifted downfield as the SOC reached 100% (Figure S10).…”