title: Radiation-Grafted Polymer Electrolyte Membranes for Water Electrolysis Cells: Evaluation of Key Membrane Properties.
abstract: Radiation-grafted membranes can be considered an alternative to perfluorosulfonic acid (PFSA) membranes, such as Nafion, in a solid polymer electrolyte electrolyzer. Styrene, acrylonitrile, and 1,3-diisopropenylbenzene monomers are cografted into preirradiated 50 μm ethylene tetrafluoroethylene (ETFE) base film, followed by sulfonation to introduce proton exchange sites to the obtained grafted films. The incorporation of grafts throughout the thickness is demonstrated by scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM/EDX) analysis of the membrane cross-sections. The membranes are analyzed in terms of grafting kinetics, ion-exchange capacity (IEC), and water uptake. The key properties of radiation-grafted membranes and Nafion, such as gas crossover, area resistance, and mechanical properties, are evaluated and compared. The plot of hydrogen crossover versus area resistance of the membranes results in a property map that indicates the target areas for membrane development for electrolyzer applications. Tensile tests are performed to assess the mechanical properties of the membranes. Finally, these three properties are combined to establish a figure of merit, which indicates that radiation-grafted membranes obtained in the present study are promising candidates with properties superior to those of Nafion membranes. A water electrolysis cell test is performed as proof of principle, including a comparison to a commercial membrane electrode assembly (MEA).
authors.affiliation: Electrochemistry Laboratory, Paul Scherrer Institut , CH-5232 Villigen PSI, Switzerland.
authors.forename: Albert
authors.initials: A
authors.lastname: Albert
authors.affiliation: New Energy Solutions, SINTEF Materials and Chemistry , NO-7465 Trondheim, Norway.
authors.forename: Alejandro O
authors.initials: AO
authors.lastname: Barnett
authors.affiliation: New Energy Solutions, SINTEF Materials and Chemistry , NO-7465 Trondheim, Norway.
authors.forename: Magnus S
authors.initials: MS
authors.lastname: Thomassen
authors.affiliation: Electrochemistry Laboratory, Paul Scherrer Institut , CH-5232 Villigen PSI, Switzerland.|Laboratory of Physical Chemistry, ETH Zürich , CH-8093 Zürich, Switzerland.
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Schmidt
authors.affiliation: Electrochemistry Laboratory, Paul Scherrer Institut , CH-5232 Villigen PSI, Switzerland.
authors.forename: Lorenz
authors.initials: L
authors.lastname: Gubler
keywords: Nafion; electrolyzer; fuel cell; gas crossover; mechanical properties; polymer electrolyte; radiation-grafted membrane; resistance