Performance and mass transport in open metallic element architecture fuel cells at ultra-high current density

Abstract

Performance and mass transport of a polymer electrolyte fuel cell (PEFC) with an open metallic element (OME) flow field architecture were analyzed in comparison to a conventional parallel channel/land (C/L) fuel cell, using low humidity at the anode and dry oxidant at the cathode. Under identical conditions the OME cell was able to operate at a current density of 3 A cm−2, recording a peak power of 1.2 W cm−2, compared to 0.9 W cm−2 using a parallel cell. Area specific resistance (ASR) was lower for the OME cell as a result of more uniform compression and reduced contact resistance. Electrochemical impedance spectroscopy (EIS) revealed great improvement in mass transport compared to a parallel C/L cell. A heliox mixture at the cathode of both cells revealed improved mass transport for the parallel cell, but revealed no oxygen gas phase transport limitation at high current densities for the OME architecture. In fact, it was shown that with an OME architecture, limitation at ultra-high current density results from dehydration at the anode and not reactant mass transport. This also indicates that ionomer film resistances at the electrode do not preclude operation at extremely high currents.