Highly Water-Soluble 6-Quinoxalinecarboxylic Acid for High-Voltage Aqueous Organic Redox Flow Batteries
Caixing Wang, Yanrong Wang, Tao Meng, Bo Yu, Kaiqiang Zhang, Jie Wei, Yuzhu Liu, Pengbo Zhang, Guochun Ding, Zuoxiu Tie, Jianyu Cao, Zhong Jin
Abstract
Aqueous organic redox flow batteries (AORFBs) are promising for grid-scale energy storage, but the aqueous solubility and stability of redox-active organic molecules are usually low. Herein, we report scalable and convenient synthesis of 6-quinoxalinecarboxylic acid (QCA) anolyte material with high solubility (5.5 M) and ultralow redox potential (−0.79 V vs SHE). When coupling with K4Fe(CN)6 catholyte, the QCA||K4Fe(CN)6 AORFBs show a cell voltage of 1.28 V, a power density of 199 mW cm–2, and a capacity retention of 99.9% cycle–1. This work highlights the reasonable construction of redox-active organic species to develop advanced AORFBs toward large-scale energy storage applications.