Quaternized poly(arylene ether benzonitrile) membranes for vanadium redox flow batteries

• Published in: Journal of membrane science 2021-01, Vol.617, p.118565, Article 118565
• Main Authors: Park, Eun Joo, Maurya, Sandip, Martinez, Ulises, Kim, Yu Seung, Mukundan, Rangachary
• Format: Article
• Language: English
• Subjects: Anion exchange membranes; Electrochemical energy storage; Poly(arylene ether benzonitrile); Vanadium redox flow battery
• ISSN: 0376-7388; 1873-3123
• DOI: 10.1016/j.memsci.2020.118565

A series of quaternized poly (arylene ether benzonitrile)s (QAxCN; x = percent quaternization) were synthesized for the vanadium redox flow battery (VRFB) application. The presence of highly polar nitrile groups incorporated in the quaternized polymer chain provides desirable polymer properties (low water uptake, high dimensional stability and low VO2+ permeability) without compromising ion conductivity. VRFB single cells using the aforementioned membranes showed excellent performance. The cell using a 15 μm-thick QA50CN membrane exhibited superior coulombic efficiency (98.2%) and comparable energy efficiency (86.5%) at 40 mA cm-2 compared to the single cell using Nafion-212 with a coulombic efficiency of 95.5% and an energy efficiency of 86.2%. The cell cycling stability and membrane oxidative stability data confirmed that the QAxCN membranes have the potential to replace Nafion membranes for energy storage in VRFB applications. [Display omitted] •Developed quaternized poly (arylene ether benzonitrile) membranes (QAxCN) for vanadium redox flow batteries.•QAxCN membranes show 4 orders of magnitude lower VO2+ crossover than Nafion® membranes of comparable thickness.•A 15 μm thick QA50CN membrane exhibited better coulombic and energy efficiency than those of Nafion 212 and 117 membranes.•A 48 μm thick QA50CN membrane was cycled 50 times without any electrolyte rebalancing with