本論文主要在探討被動式直接甲醇燃料電池性能衰退原因與對策研究。由於DMFC電池組關機時，容易因保存不良造成電池性能衰退，因此丞待解決。本研究發現可利用隔離氧氣與電極的接觸方式，使電池組在不操作時不會被毒化，故在電池下次使用時性能不致衰退。
研究發現DMFC電池組性能衰退原因主要有三，不操作或操作時殘餘甲醇crossover到陰極導致觸媒毒化、交換膜因過度蒸發缺水導致傳導氫離子能力下降或交換膜與擴散層因膨脹率不同導致交換膜與電極剝離等三大類，本論文已針對上述問題提出解決的對策。實驗發現將陰陽極用去離子水覆蓋使其與大氣隔離的保存方式，可避免電極直接與空氣接觸，造成殘存甲醇與氧氣反應使Pt毒化。此外泡水亦可因MEA得到充分濕潤讓導氫離子能力不會降低，亦不會因不當保存時，交換膜與電極伸縮率不同，造成電極剝離，使性能衰退。
為了將來使用方便，本研究最後模擬DMFC使用的狀況，將DMFC Stack，陽極填滿2M甲醇溶液，陰極則噴適量去離子水以隔離空氣，其結果發現，如此亦可降低電池性能的衰退。未來可將這些技術應用在其它可攜式DMFC電池組，商品化應該極有可能。
關鍵字：直接甲醇燃料電池、甲醇溶液、crossover、衰退、碳纖維束

The major work in this thesis is the studies of the performance decay and the strategies in solving this problem for a passive direct methanol fuel cell. When a DMFC stack is not in operating condition, the performance of this fuel cell may decay due to improper storage. In our study, it is found that the stack will not be poisoned or not decay in the next operation by isolating the electrode from atmosphere.
The three major possibilities causing the decay of the performance found in this study are the poison in the cathode due to the crossover of the methanol; the conductivity decay of proton due to the shortage of water within the membrane; and the strip the electrode from the membrane due to different expansibilities. The strategies in solving above problems proposed in this study is making use the de-ion water to cover the anode and the cathode to isolate the two electrodes from the atmosphere. This will keep away off the contact with the oxygen directly and to avoid the poison of Pt due to the reaction between methanol solution and oxygen. In addition, the MEA soaking in the water can make the membrane wet sufficiently so that the conductivity of the proton will not decay. It will also be able to avoid the electrode strip from the membrane.
In the final, we simulate the condition of the application that the methanol solution is directly stored in the anode chamber, and we spray appropriate amount de-ion water in cathode to isolated the two electrodes from air. The experimental results also show that the decay of the performance of the stack is reduced apparently. Those techniques may apply to a portable DMFC system. We expect that the commercialization of DMFC stacks is possible in the near future.
Keywords: DMFC, methanol solution, crossover, decay, carbon fiber bunch

論文審定書 .................................................................................................... i
誌謝 ............................................................................................................... ii
摘要 .............................................................................................................. iii
Abstract ...................................................................................................... iv
目錄 .............................................................................................................. vi
圖目錄 .......................................................................................................... ix
表目錄 ........................................................................................................ xiv
第一章緒論 ................................................................................................. 1
1.1 前言 ................................................................................................ 1
1.2 燃料電池類型 ................................................................................ 2
1.3 文獻回顧 ........................................................................................ 4
1.4 研究目的 ...................................................................................... 11
第二章直接甲醇燃料電池工作原理與架構 ........................................... 12
2.1 DMFC工作原理 .......................................................................... 12
2.1.1 DMFC理論效率 ............................................................... 13
2.2 DMFC燃料消耗量 ...................................................................... 14
2.3 水量覆蓋理論值 ........................................................................... 16
2.4 DMFC 架構 .................................................................................. 17
2.4.1膜電極組(Membrane Electrode Assembly；MEA) ......... 18
2.4.2電流收集器 ........................................................................ 21
第三章直接甲醇燃料電池組設計與製作 ............................................... 24
3.1 MEA製作 ..................................................................................... 24
3.1.1觸媒ink調配 ..................................................................... 24
3.1.2電極噴塗 ............................................................................ 25
3.1.3質子交換膜預處理 ............................................................ 25
3.1.4 MEA熱壓 .......................................................................... 26
3.2電流收集器 ................................................................................... 26
3.2.1碳纖維束製作流程 ............................................................ 27
3.3單Cell的製作 .............................................................................. 29
第四章實驗材料、設備與步驟介紹 ....................................................... 30
4.1 實驗材料 ...................................................................................... 30
4.2 實驗設備 ...................................................................................... 31
4.3 實驗步驟 ...................................................................................... 35
第五章實驗結果與討論 ........................................................................... 38
5.1 實驗條件 ...................................................................................... 38
5.2 DMFC性能衰退探討 .................................................................. 39
5.2.1電極的毒化 ........................................................................ 40
5.2.2 MEA缺水造成的影響 ...................................................... 41
5.2.3 MEA的剝離 ...................................................................... 42
5.3電池性能衰退對策 ....................................................................... 42
5.3.1電極毒化對策 .................................................................... 42
5.3.2 MEA維持適當濕潤 .......................................................... 43
5.3.3 MEA剝離對策 .................................................................. 44
5.4阻絕氧化劑保存方式對DMFC性能影響探討 ......................... 45
5.4.1保存時陽極與大氣隔離 .................................................... 46
5.4.2保存時陰極與大氣隔離 .................................................... 46
5.4.3保存時陽極與陰極皆與大氣隔離.................................... 47
5.4.4保存時陽極浸泡甲醇水溶液與陰極浸泡DIwater ......... 48
第六章結論與未來展望 ........................................................................... 50
參考文獻 ..................................................................................................... 52

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