區域PEM fuel cell之加速老化研究

The study of accelerated degradation in segmented PEM fuel cells

李君偉(Chun-Wei Li)

指導教授 ： 蘇艾

元智大學/工程學院/機械工程學系/碩士(2008年)

https://doi.org/10.6838/YZU.2008.00137

摘要

本論文使用區域分割型燃料電池，共分為八個區域，並分別使用Nafion117與Nafion212之膜材觀察相對濕度與流場方向在不同膜材厚度下對電池均勻與穩定性之影響，並找出能保有最佳之均勻穩定性的操作參數條件。
在論文中的加速老化實驗，使用了Nafion212作為高分子膜材，並利用兩種加速老化機制，電流循環之老化與氣體乾濕&電流循環之老化，而電流變動將會伴隨著暫態之overshoot現象，這樣的暫態現象會對膜電極組中的觸媒有負面影響，在實驗中發現了這兩種老化機制分別對膜電極組中的電極觸媒以及高分子膜材造成不同影響，其中電流循環主要是針對電極的觸媒，氣體的乾濕循環則是經由對高分子膜材產生膨潤收縮造成膜材的收縮與拉伸之應力破壞。
配合區域型燃料電池的加速老化實驗能夠在上述的兩種加速老化機制中得知電池中的哪一區域有先衰退而老化的情形產生，並且透過極化曲線測試、開路電壓量測、交流阻抗測試、觸媒電化學反應面積量測以及氫氣穿透電流之量測得知老化產生的原因。

關鍵字

質子交換膜燃料電池,區域型燃料電池,膜電極組老化,氫氣穿透率,觸媒電化學反應面積

並列摘要

This thesis uses an eight segment fuel cells with different thickness membranes of Nafion117 and Nafion212 to observe the effect of relative humidity and flow field direction on fuel cell stability and uniform performance, in order to find optimal operating conditions to achieve a uniform and stable fuel cell.
In the experiment investigating accelerated degradation, the membrane is Nafion 212, and the two degradation acceleration techniques used were cycling current and cycling humidity with cycling current. Experimental results shows that the two different degradation techniques will cause different effects in the membrane or catalysts; with cycling current affecting the catalyst in the electrodes, while cycling humidity with cycling current primarily affects the membrane.
Since a segmented fuel cell was used, we are able to observe the local degradation and found the downstream regions degrade faster than the others. This is due to water flooding results in downstream regions. The experiments used polarization curve test, open circuit voltage test ,AC impedance test, cyclic voltammetry test and linear sweep voltammetry test to find out the results of degradation.

並列關鍵字

PEMFC, segmented fuel cell, degradation, hydrogen crossover, electrochemical reaction surface area

參考文獻

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