Nafion®/ODF-silica composite membranes for medium temperature proton exchange membrane fuel cells
MacKinnon, Sean M.
Schulte, Karl I.
Nunes, Suzana Pereira
KAUST DepartmentWater Desalination and Reuse Research Center (WDRC)
Biological and Environmental Sciences and Engineering (BESE) Division
Environmental Science and Engineering Program
Nanostructured Polymeric Membrane Lab
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AbstractA series of composite membranes were prepared by dispersing fluorinated polyoxadiazole oligomer (ODF)-functionalized silica nanoparticles in a Nafion matrix. Both melt-extrusion and solvent casting processes were explored. Ion exchange capacity, conductivity, water uptake and dimensional stability, thermal stability and morphology were characterized. The inclusion of functionalized nanoparticles proved advantageous, mainly due to a physical crosslinking effect and better water retention, with functionalized nanoparticles performing better than the pristine silica particles. For the same filler loading, better nanoparticle dispersion was achieved for solvent-cast membranes, resulting in higher proton conductivity. Filler agglomeration, however,was more severe for solvent-castmembranes at loadings beyond 5wt.%. The composite membranes showed excellent thermal stability, allowing for operation in medium temperature PEM fuel cells. Fuel cell performance of the compositemembranesdecreaseswithdecreasing relativehumidity, but goodperformance values are still obtained at 34% RHand 90 °C,with the best results obtained for solvent castmembranes loaded with 10 wt.% ODF-functionalized silica. Hydrogen crossover of the composite membranes is higher than that forpureNafion membranes,possiblydue toporosityresulting fromsuboptimalparticle- matrixcompatibility. © 2013 Crown Copyright and Elsevier BV. All rights reserved.
SponsorsThe authors would like to thank S. Neumann and Dr. T. Emmler for their contribution to the SEM, and thermal characterizations; F. Vachon, N. Raymond, and P. Le Marquand for their contribution to membrane and MEA processing and characterization. The authors gratefully acknowledge the funding provided by the NRC-Helmholtz Association Cooperation project on MEAs for high temperature fuel cells. Finally, the authors would like to acknowledge the editor's insightful comments.
JournalJournal of Power Sources