A series of designed experiments similar to those presented in Rahim et al  is performed using the selected ranges of each parameter. A total of nine MEAs with different parameters are evaluated using polarization curves and electrochemical impedance spectroscopy (EIS) in single cells with an active area of 14.44 cm2. The impedance measurements are performed in the low current density regime (up to 100 mA/cm2) and with a very high cathode stoichiometry (operation as a differential cell – constant conditions inside the cell with hardly any depletion of oxygen between inlet and outlet). This makes it possible to characterize the CCL on the basis of characteristic fuel cell parameters by almost eliminating the mass transport losses within the CCL. Cell impedance is measured at four selected current densities of 10, 20, 50 and 100 mA/cm2. The impedance spectra are fitted with an equivalent circuit model (ECM) to extract the ohmic resistance (RΩ) of the cell, the activation resistance (Ract), the protonic resistance (Rp) and the double layer capacitance (Cdl) of the CCL. All of these cell parameters are found to be a strong function of current density in agreement with some of the observations made by Wippermann et al , especially concerning the RΩ.
Finally, a comparison is made between all MEAs and the optimum level for each material parameter is analyzed based on the obtained cell parameters and a discussion of the underlying physics.
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