title: Tuning the Perfluorosulfonic Acid Membrane Morphology for Vanadium Redox-Flow Batteries.
abstract: The microstructure of perfluorinated sulfonic acid proton-exchange membranes such as Nafion significantly affects their transport properties and performance in a vanadium redox-flow battery (VRB). In this work, Nafion membranes with various equivalent weights ranging from 1000 to 1500 are prepared and the morphology-property-performance relationship is investigated. NMR and small-angle X-ray scattering studies revealed their composition and morphology variances, which lead to major differences in key transport properties related to proton conduction and vanadium-ion permeation. Their performances are further characterized as VRB membranes. On the basis of this understanding, a new perfluorosulfonic acid membrane is designed with optimal pore geometry and thickness, leading to higher ion selectivity and lower cost compared with the widely used Nafion 115. Excellent VRB single-cell performance (89.3% energy efficiency at 50 mA·cm-2) was achieved along with a stable cyclical capacity over prolonged cycling.
authors.affiliation: Pacific Northwest National Laboratory , 902 Battelle Boulevard, Richland, Washington 99354, United States.
authors.forename: M
authors.initials: M
authors.lastname: Vijayakumar
authors.affiliation: Pacific Northwest National Laboratory , 902 Battelle Boulevard, Richland, Washington 99354, United States.
authors.forename: Qingtao
authors.initials: Q
authors.lastname: Luo
authors.affiliation: The Chemours Company , 22828 Highway 87 South, Fayetteville, North Carolina 28306, United States.
authors.forename: Ralph
authors.initials: R
authors.lastname: Lloyd
authors.affiliation: Pacific Northwest National Laboratory , 902 Battelle Boulevard, Richland, Washington 99354, United States.
authors.forename: Zimin
authors.initials: Z
authors.lastname: Nie
authors.affiliation: Pacific Northwest National Laboratory , 902 Battelle Boulevard, Richland, Washington 99354, United States.
authors.forename: Xiaoliang
authors.initials: X
authors.lastname: Wei
authors.affiliation: Pacific Northwest National Laboratory , 902 Battelle Boulevard, Richland, Washington 99354, United States.
authors.forename: Bin
authors.initials: B
authors.lastname: Li
authors.affiliation: Pacific Northwest National Laboratory , 902 Battelle Boulevard, Richland, Washington 99354, United States.
authors.forename: Vincent
authors.initials: V
authors.lastname: Sprenkle
authors.affiliation: DuPont Central Research and Development , 700-707 Powder Mill Road, Wilmington, Delaware 19880, United States.
authors.forename: J-David
authors.initials: JD
authors.lastname: Londono
authors.affiliation: The Chemours Company , P.O. Box 8352, Wilmington, Delaware 19803, United States.
authors.forename: Murat
authors.initials: M
authors.lastname: Unlu
authors.affiliation: Pacific Northwest National Laboratory , 902 Battelle Boulevard, Richland, Washington 99354, United States.
authors.forename: Wei
authors.identifier: http://orcid.org/0000-0002-5453-4695
authors.initials: W
authors.lastname: Wang
keywords: 19F NMR; Nafion; SAXS; ion-exchange membrane; redox-flow battery