摘要
本論文除探討如何提升可攜式直接甲醇燃料電池的性能並研究如何維持電池操作時的穩定。本研究首先探討碳纖維束內部結構改良對性能之影響，藉由在纖維束膠合區加入不同厚度的銅片以形成碳纖維束柔軟端的額外小通道，接著在碳纖維束適當位置切割橫向槽，以縮短氣流通路，使肋條下方的電極亦能得到足夠燃料與氧化劑。實驗結果顯示，從碳纖維束無結構改成膠合端放置銅片0.5mm厚的銅片，並在等距切割兩個橫向槽後，最大功率密度可由無結構的20mW/cm2提升至有結構時的24 mW/cm2，大約提升了20%。此實驗說明了內部結構改良對性能可有明顯幫助。
為了減少燃料不必要的耗損，本研究在裸露的交換膜區貼上阻隔膜可減少甲醇與水的滲透洩漏，改良後燃料利用率約提升24%。為使直接甲醇燃料電池能夠穩定操作，本研究以自然的重力及擴散方式，補充被消耗掉的燃料，以維持反應室內的甲醇溶液濃度穩定，藉由調控制閘門來改變擴散膜面積大小，調整燃料補充流率，並利用多條棉線與軟管將補充的燃料輸送至陽極反應室的底部，這種多點式補充可讓陽極反應室甲醇溶液可較均勻分布，使電池維持長時間穩定操作。
為了使未來電池體積能縮小，將儘量減少陽極反應室容積，但縮小後的反應室在大電流時，仍能有足夠燃料可補充，因此本研究亦探討不同反應室大小的電壓暫態變化，希望能找出能滿足需求的最適當空間。這些最佳化的結果，希望可提供將來可攜式多電池DMFC設計與製作時的參考。

Abstract
The improvement of performance and the maintenance of stability of a portable air-breathing DMFC are studied in this thesis. The effect of the improvement of the internal structural of carbon fiber bunches on the cell performance is studied firstly. The small channels in the soft end of the carbon fiber bunches can be formed by changing the thickness of the copper plates burry within the gluing zone of the fiber bunches. Then one or two transverse grooves are form in proper location by cutting part of the carbon fibers at the soft end to shorten the airflow path to the area of electrode which is covered by the carbon fiber bunches so that the reaction area can obtained enough oxygen or fuel. Experimental results show that the maximum power density is about 20 mW/cm2 with no structure but it raised to about 24 mW/cm2 with the burry a 0.5mm thick copper plate and the two transverse grooves. It improves about 20% power density. The experiments prove that the improvement of the internal structure of the carbon fiber bunches is helpful in stack performance.
In order to reduce the unneeded depletion of fuel, the bare nafion membrane pastes another special membrane to block methanol and water leakage. The strategy to block the leakage improved the rate of fuel utilization about 24%. In order to make the direct methanol fuel cell operating stably, a fuel supplying system by gravitation and diffusion forces is delivering the consumed fuel to maintain the concentration of methanol solution in anode reaction, by adjusting a sliding gate to control the diffusion area and utilizing three cotton threads and hoses to distribute the fuel to proper location. The multi-point type of fuel supplementary system allows the methanol solution to be distributed uniformly, so that the stack can maintain stable operation for a long period.
In order to make the stack size to a minimization, the volume of the anode reaction chamber will be minimized as possible; however, the reduced chamber is still able to supply sufficient fuel maintaining operating stably in the high-current condition. The transient phenomena of output voltage under the various volume of the reaction chamber are also studied in this research. Finally, we hope to be able to identify the most appropriate space to meet demand. The above optimization results are able to provide a reference in the future design and production of portable DMFCs.

目錄
目錄 ................................................................................................................ i
圖目錄 ............................................................................................................ v
表目錄 ............................................................................................................ x
摘要 .............................................................................................................. xi
Abstract ...................................................................................................... xiii
第一章 緒論................................................................................................. 1
1.1 前言................................................................................................ 1
1.2 燃料電池 ....................................................................................... 2
1.3 文獻回顧 ....................................................................................... 4
1.4 研究目的 ..................................................................................... 13
第二章 直接甲醇燃料電池(DMFC) ......................................................... 14
2.1直接甲醇燃料電池的結構 .......................................................... 14
2.1.1膜電極組( Membrane Electrode Assembly,MEA) ........... 15
2.1.2質子交換膜 ....................................................................... 15
2.1.3電極 ................................................................................... 16
2.1.4觸媒層 ............................................................................... 16
2.1.5擴散層 ............................................................................... 18
2.1.6電流收集板 ....................................................................... 18
2.2直接甲醇燃料電池DMFC工作原理 ......................................... 21
2.2.1 DMFC反應原理 ............................................................... 21
2.2.2甲醇於DMFC中之理論消耗量 ...................................... 23
第三章 DMFC元件製作 ........................................................................... 28
3.1碳纖維束 ...................................................................................... 28
3.1.1碳纖維束製作流程 ........................................................... 28
3.1.2碳纖維束結構之製作 ....................................................... 31
3.1.3碳纖維束挖槽 ................................................................... 31
3.2 MEA製作 ..................................................................................... 32
3.2.1電極預備 ........................................................................... 32
3.2.2質子交換膜處理 ............................................................... 32
3.2.3 MEA熱壓.......................................................................... 33
3.3單Cell的製作 .............................................................................. 34
3.4甲醇與水儲存槽 .......................................................................... 34
第四章 實驗方法 ....................................................................................... 36
4.1 實驗材料、設備與方法 ............................................................. 36
4.1.1實驗材料 ........................................................................... 36
4.1.2實驗設備 ........................................................................... 37
4.1.3實驗方法 ........................................................................... 39
4.2實驗步驟 ...................................................................................... 41
4.2.1性能量測步驟 ................................................................... 41
4.2.2甲醇與水對膜的滲透蒸散率實驗步驟 ........................... 42
4.2.3控制陽極反應室大小步驟 ............................................... 42
4.2.4補充管路設計與製作步驟 ............................................... 43
4.2.5有無阻隔膜製作 ............................................................... 43
第五章 實驗結果與討論 ........................................................................... 44
5.1 實驗條件 ..................................................................................... 45
5.2碳纖維束內部結構對性能的影響 .............................................. 46
5.2.1碳纖維束內放置銅片對性能的影響 ............................... 46
5.2.2碳纖維束內放置銅片厚度對性能的影響 ....................... 47
5.2.3碳纖維束橫向溝槽對性能的影響 ................................... 47
5.2.4陽極碳纖維束內部結構對性能的影響 ........................... 47
5.2.5改良碳纖維束後增加氧氣供應 ....................................... 48
5.3甲醇與水對膜的滲透 .................................................................. 49
5.4儲存槽到混合室甲醇與水擴散材料的選擇 .............................. 49
5.4.1甲醇擴散材料 ................................................................... 49
5.4.2水擴散材料 ....................................................................... 50
5.5儲存室到反應室燃料輸送材料選擇 .......................................... 50
5.6不同負載甲醇與水消耗率 .......................................................... 51
5.7阻隔膜對減少滲透蒸發的影響 .................................................. 52
5.7.1有無阻隔膜對電壓穩定性的影響 ................................... 53
5.7.2阻隔膜對燃料利用率的影響 ........................................... 54
5.8無補充甲醇溶液性能穩定性探討 .............................................. 54
5.9有補充甲醇溶液性能穩定性探討 .............................................. 55
5.10甲醇溶液濃度對電壓穩定性的影響 ........................................ 56
5.11陽極反應室大小對性能穩定性的影響 .................................... 57
第六章 結論................................................................................................ 58
參考文獻 ...................................................................................................... 60
圖目錄
圖2.1燃料電池結構與工作原理示意圖 .................................................. 64
圖2.2 MEA與傳統硬質表面單極板結合示意圖 .................................... 64
圖2.3 MEA與新型碳纖維束單極板結合示意圖 .................................... 65
圖2.4密度與濃度之關係(1~25M) ............................................................ 65
圖3.1台麗朗24K碳纖維束 ..................................................................... 66
圖3.2碳纖維束展開情形 .......................................................................... 66
圖3.3自動上膠機 ...................................................................................... 67
圖3.4上膠機之上膠動作 .......................................................................... 67
圖3.5完成一層之上膠碳纖維 .................................................................. 68
圖3.6上膠機上完膠後碳纖維片每間隔2cm放置一條2mm固態膠 ... 68
圖3.7手動裁刀機 ...................................................................................... 69
圖3.8製作完成之碳纖維片，長約5cm，寬約2cm .............................. 69
圖3.9碳纖維束推疊前材料及模具 .......................................................... 70
圖3.10碳纖維片推疊步驟，重覆b~e直到所需層數 ............................ 71
圖3.11碳纖維片中埋入銅片推疊步驟 .................................................... 72
圖3.12使用鍍銀線將導線往膜具兩旁固定 ............................................ 73
圖3.13堆疊完成熱壓前碳纖維束 ............................................................ 73
圖3.14推疊好的碳纖維放置於熱壓模具內熱壓 .................................... 73
圖3.15熱壓完切割前碳纖維束照片 ........................................................ 74
圖3.16碳纖維束切割裝置 ........................................................................ 74
圖3.17熱壓完碳纖維束對切後照片 ........................................................ 75
圖3.18碳纖維束完成修整後並加裝ㄇ型不銹鋼條單極板 .................... 75
圖3.19碳纖維束埋入銅片形成之結構示意圖 ........................................ 76
圖3.20碳纖維束銅片埋設與挖槽之結構示意圖 .................................... 76
圖3.21單電池膜電極組熱壓所需材料 .................................................... 77
圖3.22電極熱壓模具 ................................................................................ 77
圖3.23三點式熱壓機 ................................................................................ 78
圖3.24熱壓完成之單電池MEA .............................................................. 78
圖3.25可控制甲醇與水流率的燃料供應裝置示意圖 ............................ 79
圖3.26可控制甲醇與水流率的燃料供應裝置圖 .................................... 79
圖3.27可控制甲醇與水流率的燃料供應裝置爆炸圖 ............................ 80
圖3.28可控制甲醇與水流率的燃料供應裝置零件圖 ............................ 80
圖4.1單電池零件圖 .................................................................................. 81
圖4.2組裝完成的單電池 .......................................................................... 81
圖4.3溫度計............................................................................................... 82
圖4.4加熱器............................................................................................... 82
圖4.5精密電子秤 ...................................................................................... 83
圖4.6微量注射針筒 .................................................................................. 83
圖4.7電子負載器 ...................................................................................... 84
圖4.8超純水製造機 .................................................................................. 84
圖4.9防甲醇與水滲透用阻隔膠帶 .......................................................... 85
圖4.10不同碳纖維束結構電阻之比較 .................................................... 85
圖4.11有無挖槽之電阻比較..................................................................... 86
圖4.12 裸露膜滲透蒸發率測試裝置 ....................................................... 86
圖4.13單電池Stack與溶液容量調節條組合圖 ..................................... 87
圖4.14棉線管零件圖與組合圖 ................................................................ 87
圖4.15單電池組與補充進反應室棉線組合圖 ........................................ 88
圖4.16單電池有無使用阻隔膜圖 ............................................................ 88
圖5.1碳纖維束內放置銅片對性能的影響 .............................................. 89
圖5.2碳纖維束內不同銅片厚度對性能的影響 ...................................... 89
圖5.3碳纖維束有挖槽對性能的影響 ...................................................... 90
圖5.4陽極碳纖維束內部結構對性能的影響 .......................................... 90
圖5.5改良碳纖維束後增加氧氣供應 ...................................................... 91
圖5.6初始濃度2M容量20cc，無電流操作下，甲醇與水對膜(4cm2)的滲透蒸散速率隨溫度之變化 ................................................................. 92
圖5.7PVC防水膠布料不同擴散面積，甲醇的擴散量隨時間之變化，
平均擴散通量約81mg/hr•cm2 ................................................................. 92
圖5.8不同擴散面積，水的擴散量隨時間之變化，平均擴散通量約為60mg/hr•cm2 .............................................................................................. 93
圖5.9棉線對甲醇水溶液吸收量隨時間之變化，吸收率約為3630mg/hr ...................................................................................................................... 93
圖5.10補充進反應室的甲醇溶液隨時間之擴散變化 ............................ 94
圖5.11單電池電壓隨電流密度變化之關係 ............................................ 95
圖5.12無燃料補充無阻隔膜，不同定電流下，單電池電壓隨時間之變化 .............................................................................................................. 95
圖5.13單cell定電流140mA下有無阻隔膜對電壓穩定性的影響 ...... 96
圖5.14裸露區有無阻隔膜(a)甲醇(b)水消耗率之比較 ........................... 97
圖5.15陰陽極有無阻隔膜燃料利用率之比較 ........................................ 97
圖5.16無燃料補充貼阻隔膜，不同定電流下，單電池電壓隨時間之變化 .............................................................................................................. 98
圖5.17無燃料補充不同定電流下，反應區溫度隨時間之變化 ............ 98
圖5.18無燃料補充不同定電流下，甲醇與水的理論與實際平均消耗率隨電流之變化 ......................................................................................... 99
圖5.19初始濃度2M，有電流操作下，甲醇與水對MEA的滲透蒸散速率隨溫度之變化 ..................................................................................... 99
圖5.20定電流185mA，初始2M甲醇溶液1.2cc，燃料補充率甲醇52 mg/hr及水90 mg/hr，輸出電壓與反應區溫度隨時間之變化 ............. 100
圖5.21定電流225mA，初始2M甲醇溶液1.2cc，燃料補充率甲醇61 mg/hr及水113 mg/hr，輸出電壓與反應區溫度隨時間之變化 ........... 100
圖5.22不同定電流下，電壓隨濃度變化之比較52 mg/hr及水90 mg/hr，輸出電壓與反應區溫度隨時間之變化 ................................................... 101
圖5.23不同陽極chamber大小，初始濃度2M及電流225mA下電壓與濃度隨時間之變化 ............................................................................... 101
表目錄
表5.1電流185mA(82.2mA/cm2)補充速率甲醇52mg/hr及水90mg/hr，補充五小時前後甲醇水溶液濃度變化 ................................................... 102
表5.2電流225mA(100mA/cm2)補充速率甲醇61mg/hr及水113mg/hr，補充五小時前後甲醇水溶液濃度變化 .................................................. 103

參考文獻
1. “Water and air management systems for a passive direct methanol fuel
cell,” Gregory Jewett, Zhen Guo, Amir Faghri, Journal of Power Sources 168 (2007) 434–446.
2. “Comparative studies of configurations and preparation methods for
direct methanol fuel cell electrodes,” Qing Mao, Gongquan Sun, Suli Wang , Hai Suna, Guoxiong Wang ,Yan Gao, Aiwei Ye , Yang Tian , Qin Xin , Electrochimica Acta 52 (2007) 6763–6770.
3. “Optimization of properties and operating parameters of a passive
DMFC mini-stack at ambient temperature,” V. Baglio, A. Stassi, F.V. Matera, A. Di Blasi, V. Antonucci, A.S. Arico, Journal of Power Sources 180 (2008) 797–802.
4. “Development of a 1 W passive DMFC,” Zhen Guo, Amir Faghri,
International Communications in Heat and Mass Transfer 35 (2008) 225–239.
5. “A novel MEA architecture for improving the performance of a DMFC,” Chunguang Suo , Xiaowei Liu, XiaoChuan Tang, Yufeng Zhang, Bo Zhang, Peng Zhang, Electrochemistry Communications 10 (2008) 1606–1609.
6. “Fabrication and evaluation of membrane electrode assemblies by low-temperature decal methods for direct methanol fuel cells,” Jae Hyung Cho, Jang Mi Kim, Joghee Prabhurama, Sang Youp HwangDong June Ahn, Heung Yong H, Soo-Kil Kim, Journal of Power Sources 187 (2009) 378–386.
7. “Performance characteristics of a vapor feed passive miniature direct
methanol fuel cell,” Gregory Jewett, Zhen Guo, Amir Faghri, International Journal of Heat and Mass Transfer 52 (2009)4573–4583.
8. “The performance and mechanism of multi-step activation of MEA for DMFC,” Guicheng Liu, Junyuan Xu, Tongtao Wang, Tingting Zhao, Meng Wang, Yituo Wang, Jianling Li, Xindong Wang,i n t e r n a t i o n a l j ournal o f hydrogen energy 3 5(2010)12341-12345.
9. “Comparative study of three different catalyst coating methods for direct methanol fuel cells,” Hyung Joo Choia, Jinsoo Kim, Yongchai Kwon, Jonghee Hanc, Journal of Power Sources 195 (2010) 160–164.
10. “A direct methanol fuel cell system to power a humanoid robot,” Han-Ik Joha,b, Tae Jung Haa, Sang Youp Hwanga, Jong-Ho Kima, Seung-Hoon Chaea, Jae Hyung Choa, Joghee Prabhurama, Soo-Kil Kima, Tae-Hoon Lima, Baek-Kyu Choc, Jun-Ho Ohc, Sang Heup Moon, Heung Yong Haa,Journal of Power Sources 195 (2010) 293–298.
11. “Structural optimization of the direct methanol fuel cell passively fed with a high-concentration methanol solution,” Xianglin Li, Amir Faghri, Chao Xu, Journal of Power Sources 195 (2010) 8202–8208.
12. “Effect of black catalyst ionomer content on the performance of passive DMFC,” Mohammad Ali Abdelkareema, Takuya Tsujiguchib, Nobuyoshi Nakagawa, Journal of Power Sources 195 (2010) 6287–6293.
13. “Water management of the DMFC passively fed with a high-concentration methanol solution,” Xianglin Li, Amir Faghri, Chao Xu, i nternational journalo f hydrogen energy35 (2010) 8690-
8698.
14. “Passive direct methanol fuel cells for portable electronic devices,” F. Achmad , S.K. Kamarudin , W.R.W. Daud, E.H. Majlan, Applied Energy 88 (2011) 1681–1689.
15. “Improving the water management and cell performance for the passive vapor-feed DMFC fed with neat methanol,” Chao Xu 1, Amir Faghri*, Xianglin Li,Xianglin Li,internationaljournalofhydyrogen enregy36(2011)8468-8477.
16. “Design of a MEA with multi-layer electrodes for high concentration methanol DMFCs,” Young-Chul Park a, Dong-Hwi Kim,Seongyop Lim a,b, Sang-Kyung Kim , Dong-Hyun Peck a, Doo-Hwan Jung,
International journal of hydrogen energy 37(2012)4717-4727.
17. “Development of an advanced MEA to use high-concentration methanol fuel in a direct methanol fuel cell system,” Kyungmun Kang, Giyong Lee, Geonhui Gwak, Yongjun Choi, Hyunchul Ju, i n t e r n a t i o n a l j ournal o f hydrogen energy37(2012)6285-6291.
18. “碳纖維束單/雙極板結構對PEM燃料電池性能影響之探討,” 陳威呈，碩士論文，國立中山大學機械與機電工程學系，中華民國九十八年九月.
19. “探討不同處理方式對membrane、electrode及MEA含水量的影響及曝露於大氣中，水的蒸發引起的長度與重量的變化，以了解membrane、electrode及MEA吸水特性,” 周慶宏，碩士論文，國立中山大學機械與機電工程學系，中華民國九十九年八月.
20. “研發可長時間運作，性能穩定不易衰退的被動式可攜式直接甲醇燃料電池（DMFC）,”黃國昇，碩士論文，國立中山大學機械與機電工程學系，中華民國一百年九月.