Performance Studies and Analysis of Pt Distributed Type within MEA of PEMFC

• Main Authors: Wen-Ting Lin, 林文婷
• Other Authors: Jing-Tzung Kuo
• Format: Others
• Language: zh-TW
• Published: 2005
• Online Access: http://ndltd.ncl.edu.tw/handle/64916106936864536343

碩士 === 國立臺灣大學 === 機械工程學研究所 === 93 === This paper focuses on the heart of PEMFC (Proton Exchange Membrane Fuel Cell)—Membrane Electrode Assembly. The MEA accounts for about 80% of whole cell cost. If we can lower the manufacturing costs of the MEA, then we can reduce the whole cost of fuel cell. In the paper, we adopt the traditional hydrophobic method to make the catalyst electrode, and compare the efficiency with the MEA made by Chung-Shan Institute of Science and Technology. The structure of MEA is like sandwich, made up by gas diffusion layer, catalyst layer, polymer electrolyte membrane, and backing layer. The different composition of each layer would lead to the different performance. The hollow channel part of the graphite bipolar plate is mainly the gas reacting area, and the rib part conveys the electron. If we strengthen the ratio of flow and rib, we can make reacting gas increase. However, this action would reduce the electron transmission routes. This experiment divides the manufacture method of the electrode into two parts- flow area and rib area, also take different ways to coat catalyst layer or make the gas diffusion layer on the different areas, etc. Through this experiment, this paper aims at investigating whether the different kinds of MEA will have a influence on performance of MEA. From the experiment, we can learn that, when the catalyst is mostly distributed on flow channel, the gas would react thought the layer, and at low current density, the gas would permeate into the part covered by the rib. However, there is a bit of catalyst under ribs, so it’s not helpful to the performance. And at high current density, the gas consuming rate increase, and less gas would permeate into the rib part.At this time, if we raise the catalyst amount of flow part, then we can improve the performance. If we increase the thickness of gas diffusion layer under rib area, we can promote the mass transmission, because the gas would fully react after we increase the gas transport route of transmission direction to reduce transmit limiting.In comparison, the performance would improvement. The manufacture practiced in this paper is different from what has been done in the past. We can find that some methods would improve the MEA performance. If we can make the procedure more general, or reduce material consumption, then can reduce the fuel cell cost helpfully.