Material for Redox Flow Battery Exhibiting Long Lifetime

　Redox flow batteries (RFBs) have been developed for application as scalable stationary batteries, and they are promising energy storage systems for a smart grid that balance power supply and demand. Organic RFBs, fabricated by organic-based redox active electrolytes, have received considerable attention as they are potentially much less expensive than vanadium-based flow batteries. However, one drawback of organic RFBs is their relatively low chemical stability. Early research papers indicates that most show high temporal capacity fade rates of 0.1-3.5%/day, which limits their long-term use.¹⁾
　Gordon and Aziz et al. recently reported that an organic RFB made with 2,6-DBEAQ (1) exhibits a long lifetime, losing less than 0.01% of their capacity per day and less than 0.001% of its capacity per cycle. The chemical structure of 1 involves anthraquinone and soluble carboxy groups, and 1 shows good chemical stability and solubility in alkaline solution (0.6 M at pH 12, 1.1 M at pH 14). Pairing a 1-based negative electrolyte with a potassium ferrocyanide-based positive electrolyte results in a battery with an open-circuit voltage of 1.05 V and a theoretical volumetric energy density of 17 Wh/L at pH 12.²⁾