| Summary: | 碩士 === 元智大學 === 化學工程與材料科學學系 === 104 === Currently, the proton exchange membrane fuel cells (PEMFCs), which are used as power systems of small vehicles, such as scooter, folk-lift, material handling vehicles etc., are normally operated at a temperature of 50-60°C and a relative humidity of ~40-60 %RH. In this study, we prepared a membrane electrode assembly (MEA), which was composed of a Nafion-211 (thickness ~25 m) membrane, anode and cathode gas diffusion layers (GDLs; in which the total GDL thickness and the microporous layer (MPL; including PTFE and carbon powder) thickness were ~ 410 m and 70 m, respectively), and anode and cathode catalyst layers (CLs; the anode and cathode Pt loadings were 0.2 mg/cm2 and 0.4 mg/cm2, respectively). We demonstrated that this MEA had a maximum power density of 648 mW/cm2 when the PEMFC was operated at 50oC with 40% RH. The on (operated at a constant current density i= 400 mA/cm2, 50°C, and 40 %RH for 10 h)/ off (i= 0 mA/cm2, under ambient environment for 14 h) cycle test showed a slow voltage decay rate of 1.14x10-3 V/cycle at i= 400 mA/cm2. The scanning electron microscope (SEM) and energy dispersion spectroscopy (EDS), and impedance analyses revealed that the migration aggregation of cathode Pt was the main reason for the MEA voltage decay during the on/off cycle life test.
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