| Summary: | 碩士 === 大同大學 === 機械工程學系(所) === 98 === In this study of proton exchange membrane fuel cell, we discuss about the relationship between the optimal amount of PTFE contents and the compression ratio in the gas diffusion layer (GDL) and the micro porous layer (MPL). We should note that the efficiency of the proton exchange fuel cell could vary greatly since different compression ratios are applied to the fuel cell during the process of making it. Insufficient compression ratio would result in fuel leak, an increase in the system resistance, and a decrease in the battery performance while an excessive compression ratio would result in an increase of resistance in the gas diffusion layer, a decrease in the battery performance and that this can cause the MEA to wear down. There are two parts in the study of this experiment and we will conduct tests on the polarization curve, the electrochemical impedance spectroscopy and the equivalent circuit simulation. In the first part, we use 5wt%, 10 wt%, 20wt%, and 30 wt% of PTFE in the gas diffusion layer. The result indicates that a 5 wt% of PTFE in the GDL gives the best performance. The second part is based on the 5wt% of PTFE found in the first part and we adjust the amounts of PTFE in the micro porous layer to be 5%, 10%, 20%, 30%, 40%, and 50%. We also use a Vulcan XC-72R carbon loading of 1 mg/cm2. The result shows that a 5% of PTFE in the MPL gives the best performance. The micro porous layer which can minimize the cathode flooding, and, therefore, significantly achieve a better cell performance. In this study of GDL and MPL, we find out that the gas permeability increases as the amount of PTFE decreases and the in-plane electrical resistance increases as the amount of PTFE increase.
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