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  • 1. Bultel, Yann
    et al.
    Wiezell, Katarina
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Jaouen, Frédéric
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Ozil, P.
    Lindbergh, Göran
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Investigation of mass transport in gas diffusion layer at the air cathode of a PEMFC2005In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 51, no 3, p. 474-488Article in journal (Refereed)
    Abstract [en]

    In a polymer electrolyte membrane fuel cell (PEMFC), slowdiffusion in the gas diffusion electrode may induce oxygen depletion when using air at the cathode. This work focuses on the behavior of a single PEMFC built with a Nafion® based MEA and an E-TEK gas diffusion layer and fed at the cathode with nitrogen containing 5, 10 and 20% of oxygen and working at different cell temperatures and relative humidities. The purpose is to apply the experimental impedance technique to cells wherein transport limitations at the cathode are significant. In parallel, a model is proposed to interpret the polarization curves and the impedance diagrams of a single PEMFC. The model accounts for mass transport through the gas diffusion electrode. It allows us to qualitatively analyze the experimental polarization curves and the corresponding impedance spectra and highlights the intra-electrode processes and the influence of the gas diffusion layer.

  • 2.
    Gode, Peter
    et al.
    KTH, Superseded Departments, Chemical Engineering and Technology.
    Jaouen, Frederic
    KTH, Superseded Departments, Chemical Engineering and Technology.
    Lindbergh, Göran
    KTH, Superseded Departments, Chemical Engineering and Technology.
    Lundblad, Anders
    KTH, Superseded Departments, Chemical Engineering and Technology.
    Sundholm, Göran
    KTH, Superseded Departments, Chemical Engineering and Technology.
    Influence of the composition on the structure and electrochemical characteristics of the PEFC cathode2003In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 48, no 28, p. 4175-4187Article in journal (Refereed)
    Abstract [en]

    The influence the composition of the cathode has on its structure and electrochemical performance was investigated for a Nafion content spanning from 10 to 70 wt.%. The cathodes were formed on a Nafion membrane by the spray method and using 20 wt.% Pt on Vulcan (E-TEK). Materials characterisation (SEM, STEM, gas and mercury porosimetry, electron conductivity) and electrochemical characterisation (steady-state polarisation curve, impedance spectroscopy in O-2 and current-pulse measurements in N-2) were performed. The impedance spectra were analysed using our dynamic agglomerate model. The results indicate that the agglomerate model is valid until a Nafion content of about 45 wt.%. Pt/C and Nation are homogeneously mixed for any composition and no Nafion film was observed. The cathodes containing 36-43 wt.% Nation display a single or double Tafel slope behaviour ascribed to diffusion limitations in the agglomerates. At larger Nation content, the agglomerate model can describe the curves only by assuming a diffusion coefficient 3-4 decades smaller than that of gases. At such compositions, the porosity was only 10%. These results were interpreted as a blocking of the pores and a non-percolating pore system for too large Nafion contents.

  • 3.
    Jaouen, Frédéric
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Haasl, Sjoerd
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    van der Wijngaart, Wouter
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Lundblad, Anders
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Lindbergh, Göran
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Stemme, Göran
    KTH, School of Electrical Engineering (EES), Microsystem Technology.
    Adhesive copper films for an air-breathing polymer electrolyte fuel cell2005In: Journal of Power Sources, ISSN 0378-7753, E-ISSN 1873-2755, Vol. 144, no 1, p. 113-121Article in journal (Refereed)
    Abstract [en]

    A design for an air-breathing and passive polymer electrolyte fuel cell is presented. Such a type of fuel cell is in general promising for portable electronics. In the present design, the anode current collector is made of a thin copper foil. The foil is provided with an adhesive and conductive coating, which firstly tightens the hydrogen compartment without mask or clamping pressure, and secondly secures a good electronic contact between the anode backing and the current collector. The cathode comprises a backing, a gold-plated stainless steel mesh and a current collector cut out from a printed circuit board. Three geometries for the cathode current collector were evaluated. Single cells with an active area of 2 cm(2) yielded a peak power of 250-300 MW cm(-2) with air and pure H-2 in a complete passive mode except for the controlled flow of H-2. The cells' response was investigated in steady state and transient modes.

  • 4.
    Jaouen, Frédéric
    et al.
    KTH, Superseded Departments, Chemical Engineering and Technology.
    Lindbergh, Göran
    KTH, Superseded Departments, Chemical Engineering and Technology.
    Wiezell, Katarina
    KTH, Superseded Departments, Chemical Engineering and Technology.
    Transient techniques for investigating mass-transport limitations in gas diffusion electrodes: II. Experimental characterization of the PEFC cathode2003In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 150, no 12, p. A1711-A1717Article in journal (Refereed)
    Abstract [en]

    The current-interrupt technique and electrochemical impedance spectroscopy were employed in order to study the behavior of a polymer electrolyte fuel cell (PEFC) cathode containing 30 wt % Nafion and 70 wt % Pt/C. The steady-state polarization curves were also recorded. The experimental results were analyzed with help of the mathematical models developed in Part I of this paper. The effect of a varying oxygen pressure and humidity on the dynamic response of the cathode was investigated. The double-layer capacitance, Tafel slope, oxygen solubility, a group containing the effective O-2 diffusion coefficient and agglomerate size, and finally, the effective proton conductivity in the cathode were obtained. The parameter values were reasonable and attest the robustness of the agglomerate model for describing the PEFC cathode. At low humidity, a second, low-frequency loop was observed that was attributed to the membrane behavior.

  • 5.
    Wijngaart, Wouter van der
    et al.
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Jaouen, Frederic
    Haasl, Sjoerd
    KTH, School of Electrical Engineering (EES), Microsystem Technology (Changed name 20121201).
    Lundblad, Anders
    Electrochemical device2005Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    A polymer electrolyte electrochemical device comprising an anode current collector (1), a membrane electrode assembly (2) with anode and cathode gas backings (3, 4), and a cathode current collector (5), wherein the membrane electrode assembly is sealed and attached at least to the anode current collector by adhesive means, thereby creating an anode gas chamber, and optionally attached to the cathode current collector by adhesive means, said adhesive means being electrically conducting or electrically non-conducting. The invention also relates to polymer electrolyte electrochemical device components adapted for use in a single cell electrochemical device and a series arrangement electrochemical device.

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