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This paper reports novel cathode flow-field designs for passive typed air-cooled polymer electrolyte membrane fuel cells (PEMFCs) to help alleviate electrolyte dehydration and performance degradation issues under excess dry air supply conditions. The proposed flow-field designs include 7 three-dimensional (3-D) patterned designs in addition to a parallel channel configuration equipped with rectangular baffles to control the airflow for more efficient heat removal. The designs were evaluated numerically using 3-D, two-phase PEMFC simulations. Compared to a typical parallel flow channel configuration, the proposed flow-field designs show better heat removal and water retention capability. The single-cell voltage was improved around 13–75 mV at the operating current density of 0.5 A/cm2, an increase in pressure from 0.9–47-fold increase was required because of the more complex flow-field configurations. This work presents a comprehensive understanding of air-cooled PEMFC operating characteristics under excessive dry air supply conditions and a new design strategy for cathode flow fields.

Yttria doped zirconia based are the most important solid electrolytes for high temperature solid oxide fuel cell application. In this study, the tetragonal/cubic zirconia composite thin films are prepared by combination of aqueous tape casting and net shape method. The phases and microstructure of the samples are studied by X-ray diffraction and scanning electron microscope respectively. The microhardenss and toughness of thin films are measured by Vickers microhardness test. The nanohardness and Young's modulus of the specimens are evaluated by nanoindentation method. The electrical conductivity is determined by electrochemical impedance spectroscopy method. It is found that the composite electrolyte with 25 wt% of tetragonal phase content has improved mechanical and electrical properties at low temperatures and can be a suitable electrolyte for intermediate temperature solid oxide fuel cells.

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