title: Bifunctional Cross-Linking Agents Enhance Anion Exchange Membrane Efficacy for Vanadium Redox Flow Batteries.
abstract: A series of cross-linked fluorinated poly(aryl ether oxadiazole) membranes (FPAEOM) derivatized with imidazolium groups were prepared. Poly(N-vinylimidazole) (PVI) was used as the bifunctional cross-linking agent to (a) lower vanadium permeability, (b) enhance dimensional stability, and (c) concomitantly provide added ion exchange capacity in the resultant anion exchange membranes. At a molar ratio of PVI to FPAEOM of 1.5, the resultant membrane (FPAEOM-1.5 PVI) had an ion exchange capacity of 2.2 mequiv g-1, a vanadium permeability of 6.8 × 10-7cm2min-1, a water uptake of 68 wt %, and an ionic conductivity of 22.0 mS cm-1, all at 25 °C. The FPAEOM-1.5 PVI membrane showed high chemical stability in highly acidic and oxidizing vanadium solution. Single cells prepared with the FPAEOM-1.5 PVI membrane exhibited a higher Coulombic efficiency (>92%) and energy efficiency (>86%) after 40 test cycles in vanadium redox flow battery.
authors.affiliation: College of Materials Science and Engineering, Beijing University of Chemical Technology, Beijing, 100029, China.
authors.forename: Wenpin
authors.initials: W
authors.lastname: Wang
authors.affiliation: Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing, 100084, China.
authors.forename: Min
authors.initials: M
authors.lastname: Xu
authors.affiliation: Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing, 100084, China.
authors.forename: Shubo
authors.initials: S
authors.lastname: Wang
authors.affiliation: Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing, 100084, China.
authors.forename: Xiaofeng
authors.initials: X
authors.lastname: Xie
authors.affiliation: College of Materials Science and Engineering, Beijing University of Chemical Technology, Beijing, 100029, China.
authors.forename: Yafei
authors.initials: Y
authors.lastname: Lv
authors.affiliation: Department of Chemical and Biological Engineering, Illinois Institute of Technology, Chicago, Illinois 60616, United States.
authors.forename: Vijay
authors.initials: V
authors.lastname: Ramani
keywords: bifunctional cross-linker; cross-linked AEM; density functional theory (DFT); energy storage; vanadium redox flow battery