具玻璃纖維與聚四氟乙烯複合多孔隔膜之高效能磷酸燃料電池

High Performance Phosphoric Acid Fuel cell with Glass Microfiber and Polytetrafluoroethylene Composite Porous Membrane

呂佳蓮(Lu, Chia Lien)

指導教授 ： 曾繁根

國立清華大學/原子科學院/工程與系統科學系/碩士(2014年)

https://doi.org/10.6843/NTHU.2014.00311

摘要

本研究提出使用多孔性的玻璃纖維與聚四氟乙烯薄膜製成的複合膜，應用於磷酸燃料電池中做為質子傳導膜。此複合膜藉由玻璃纖維浸泡86%磷酸水溶液以具備質子傳導能力，並藉由聚四氟乙烯薄膜形成防止磷酸洩漏的保護層。
玻璃纖維與聚四氟乙烯薄膜兩者於磷酸燃料電池操作溫度150~220℃範圍皆具熱穩定性，並對磷酸具化學穩定性，成本亦相當便宜。由顯微結構分析與壓汞測孔儀可得知，玻璃纖維是具有微米等級孔洞分佈的基材，與昔日孰知應用於磷酸燃料電池之碳化矽多孔隔膜具有相似的結構，並擁有比碳化矽更高的孔隙率(93%)可含浸磷酸；聚四氟乙烯薄膜則為具奈米等級孔洞的基材，可藉親水處理讓磷酸溶液得以滲入其奈米孔洞，兩種薄膜結合可兼具富含磷酸電解質與防止磷酸洩漏之功能，其於150℃之質子傳導能力可達0.71 S/cm。
於磷酸燃料電池之單電池測試時，陰陽極使用碳布做為擴散層，觸媒層使用鉑顆粒承載於XC72碳黑上，使用噴塗法將觸媒漿料均勻塗佈於擴散層上以完成電極之製作。使用冷壓方式組成膜電極組(Membrane Electrode Assembly, MEA)後，組成一單電池進行性能的量測與探討。其最好的性能發生於使用聚四氟乙烯黏著劑比例35%，黏著鉑觸媒與碳顆粒的電極，於150℃操作溫度下，提供純氧與氫氣，其電流密度為900mA/cm2時有最高功率密度296 mW/cm2。

關鍵字

磷酸燃料電池 ； 多孔隔膜 ； 玻璃纖維 ； 聚四氟乙烯

並列摘要

The research proposes a composite membrane using glass microfiber and polytetrafluoroethylene(PTFE) thin film applied in phosphoric acid fuel cell as proton exchange membrane. The glass microfiber is soaked in 86% phosphoric acid to possess proton conductivity, and the PTFE thin film outside the glass microfiber prevents the leakage of phosphoric acid.
The glass microfiber and PTFE thin film both have thermal and chemical stability at phosphoric acid fuel cell’s working temperature 150~220℃.Otherwise, the two membrane are also very cheap. From the analysis of micron structure and mercury porosimeter, glass microfiber membrane has many micron pores that is similar to previous phosphoric acid porous membrane SiC’s structure. However, our glass microfiber has higher porosity(93%) than SiC matrix that can let glass microfiber possess more phosphoric acid contents. PTFE thin film has many nano pores. We can let PTFE nano pores fulfilled with phosphoric acid by hydrophilic treatment. The combination of two membranes possesses rich phosphoric acid electrolyte content and prevents leakage of phosphoric acid, and the composite membrane’s proton conductivity achieve 0.71 S/cm at 150℃.
When phosphoric acid fuel cell tests, anode and cathode use carbon cloth as diffusion layer. The catalyst layer is Pt/C. After cold pressing, we measure the MEA’s effects and study the phenomenon. A best fuel cell performance using the composite membrane with Pt/C and 35%PTFE binder exhibits a peak power density of 296mW/cm2 at 150℃ with H2 and pure O2.

參考文獻

[2] 衣寶廉, "燃料電池-原理與應用," 五南書局, 2007.

[29] 洪太峰, "燃料電池用含PTFE氣體擴散層之製備與性質研究," 中原大學, vol. 化學研究所, 2004.

[1] Q. Tang, K. Huang, G. Qian, and B. C. Benicewicz, "Phosphoric acid-imbibed three-dimensional polyacrylamide/poly(vinyl alcohol) hydrogel as a new class of high-temperature proton exchange membrane," Journal of Power Sources, vol. 229, pp. 36-41, 5/1/ 2013.

[5] B. Smitha, S. Sridhar, and A. A. Khan, "Solid polymer electrolyte membranes for fuel cell applications—a review," Journal of Membrane Science, vol. 259, pp. 10-26, 8/15/ 2005.

[6] P. Choi, N. H. Jalani, and R. Datta, "Thermodynamics and Proton Transport in Nafion," Journal of The Electrochemical Society, vol. 152, p. E123, 2005.