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High-Performance Alkaline Organic Redox Flow Batteries Based on 2‑Hydroxy-3-carboxy-1,4-naphthoquinone

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journal contribution
posted on 13.09.2018, 00:00 by Caixing Wang, Zhen Yang, Yanrong Wang, Peiyang Zhao, Wen Yan, Guoyin Zhu, Lianbo Ma, Bo Yu, Lei Wang, Guigen Li, Jie Liu, Zhong Jin
Aqueous redox flow batteries (ARFBs) based on the electrolyte solutions of redox-active organic molecules are very attractive for the application of large-scale electrochemical energy storage. We propose a high-performance ARFB system utilizing 2-hydroxy-3-carboxy-1,4-naphthoquinone (2,3-HCNQ) and K4Fe­(CN)6 as the anolyte and catholyte active species, respectively. The 2,3-HCNQ molecule exhibits high solubility and can carry out a reversible two-electron redox process with rapid redox kinetics. The assembled 2,3-HCNQ/K4Fe­(CN)6 ARFB delivered a cell voltage of 1.02 V and realized a peak power density of 0.255 W cm–2. The 2,3-HCNQ/K4Fe­(CN)6 ARFB can be stably operated at a current density of 100 mA cm–2 for long-term cycling (with a capacity retention of ∼94.7% after 100 cycles).