An Impedance Spectroscopy Study of a Micro PEMFC With Different Flow Fields

The H₂/air micro PEMFCs with three different flow fields were designed and fabricated in-house through a deep UV lithography technique. SU-8 photoresist was used as microstructure material for fuel cell flow-field plates. Different operational parameters were examined by electrochemical impedance spectroscopy (EIS). The operational parameters include cell operating temperature (25°C, 35°C, and 50°C), back pressures (1atm, 1.5atm, and 2atm) of reactant gases on anode site, and three different flow fields configurations (mesh, interdigitated, and serpentine). The effect of the above parameters on high frequency, medium frequency, and low frequency arc were found. The influence in terms of impedance on dynamic response of the present H₂/air micro fuel cell under different operating conditions and flow geometry can be quantitatively measured. Results are presented in the form of the polarization VI curves, PI curves, and impedance spectra under different operating conditions. The possible transport mechanisms associated with the parametric effects were discussed. In addition, it was found that, among the three flow patterns considered, significant improvements can be reached with a specified flow geometry.