Now showing 1 - 2 of 2
  • Publication
    Metadata only
    Celtec-V: a polybenzimidazole-based membrane for the direct methanol fuel cell
    (Electrochemical Society (ECS), 2007-07-30)
    Gubler, Lorenz
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    Belack, Jörg
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    Ünsal, Ömer
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    Schmidt, Thomas Justus
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    Scherer, Günther G.
    Celtec-V is a proton exchange membrane based on polybenzimidazole (PBI) comprising an interpenetrating network of polyvinylphosphonic acid designed for application in the direct methanol fuel cell. The properties and fuel cell performance of Celtec-V are investigated and compared against a Nafion 117 standard. It is shown that with the PBI-based membrane, fuel cell performance can be sustained to higher methanol feed concentration at around half the methanol crossover rate. Above 1.0 M methanol, Celtec-V outperforms Nafion 117. Furthermore, lower water permeation is observed, with Celtec-V having an electro-osmotic drag coefficient of around 1 compared to a value of 4-5 for Nafion 117. Room for improvement is identified in the ohmic resistance of the membrane and the cathode-membrane interface, where higher losses are observed at increasing current density.
  • Publication
    Metadata only
    Spatially resolved characterization of PEFCs using simultaneously neutron radiography and locally resolved impedance spectroscopy
    (Elsevier Science, 2005-11-02)
    Schneider, Ingo A.
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    Wokaun, Alexander
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    Scherer, Günther
    A method for performing neutron radiography and locally resolved impedance spectroscopy simultaneously in Situ in all operating polymer electrolyte fuel cell (PEFC) is presented. The new method provides Concurrently spatially resolved information about the local cell performance, the locally limiting processes, and the liquid water distribution. Information about the impact of water oil cell performance and limiting processes call be gained in situ oil a local scale in all operating PEFC. The method was applied to a PEFC operated oil pure H-2/O-2 in co-flow mode under low humidity operating conditions. The results show that in co-flow mode strong flooding and severe drying can Occur at the very same time in different sections of a PEFC.