| Summary: | 碩士 === 國立虎尾科技大學 === 材料科學與綠色能源工程研究所 === 96 === This thesis is to develop procedures on coating of membrane electrode assembly (MEA), the heart of the Proton Exchange Membrane Fuel Cell. The operating factors affected the performance of fuel cells, such as the method of the coating, coating positions, operating temperature, are investigated. The coating procedures on the Nafion membrane is the hardest task. The contact conditions between the catalyst layer and the Nafion membrane are improved to obtain the close attachment of them. In order to overcome the undesirable crease and expansion encountered with coating of Nafion membrane, a self-designed clamp is adopted to fix Nafion membrane tightly.
The experiments are conducted using three different methods, i.e. spraying, painting, and scraper, applied to two types of membrane, i.e. Nafion and Carbon-Cloth/Nafion. The spraying method gives the best performance compared with the painting and the scraper method, since it achieves outstanding uniformity of spraying and does not generate cracking phenomenon on the catalyst layer. Furthermore, the spraying method also gives the best performance of fuel cell on Carbon-Cloth/Nafion membrane. At low current density, the performance difference between Nafion and Carbon-Cloth/Nafion membrane is small. However, at high current density comparison, the performance of the latter significantly improves. Therefore, coating on Carbon-Cloth/Nafion gives a desirable effect under high loading. The operating temperature of cell is increased to promote its performance because higher temperature will make the catalyst reaction more active. The experimental results show that the best performance is attained ,under an operating temperature of 50℃ in the cell, using the spraying method on Carbon-Cloth/Nafion membrane under an optimal conditions of 0.203 V , the current density of 2498.6 mA/cm2, and the power density of 502 mW/cm2.
The method of the coating and coating positions in this paper is different from what has been done in the past. It is found that some methods applied here can improve the MEA performance. It can be concluded that optimizing the coating procedure of MEA will reduce material consumption and human error, and have favorable improvement on performance as well as cost reduction.
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