高溫Nafion複合膜之老化診斷與加速老化測試

Diagnosis and Accelerated Test of Composite Membrane Degradation in High Temperature PEM Fuel Cell

紀宗成(Chung-Cheng Chi)

指導教授 ： 蘇艾

共同指導教授 ： 翁芳柏(Fang-Bor Weng)

元智大學/工程學院/機械工程學系/碩士(2008年)

https://doi.org/10.6838/YZU.2008.00143

摘要

本文研究目的在於探討自製複合膜在高溫環境下長時間操作穩定性、性能老化現象及其老化機制。利用 “ In - situ ” 的診斷，包括極化曲線、交流阻抗分析、氫氣穿透以及電化學表面積的量測，暸解上述基本性質隨時間的變化。再透過 “ Ex - situ ” 的診斷，包括SEM、EDS、XRD等設備觀察膜電極組內部微結構變化與元素成分分佈的改變，得以進一步了解膜電極組老化機制。
定電流老化測試將電池操作在120℃，50%相對濕度，壓力14.7 psig，燃料與氧化劑分別為氫氣與空氣，電流負載300 mA / cm2，自製膜電極組可於此環境穩定操作160小時。加速老化測試所執行的乾溼循環時間各為6分鐘、3分鐘，乾濕循環過程分別給予30 mA / cm2與300 mA / cm2的電流負載。
定電流老化測試，嚴重的燃料穿透問題造成膜材薄化；加速老化則屬於疲勞性破壞，反覆乾濕循環造成膜材膨潤收縮，使得膜材孔洞生成的情形提前發生，反覆膨潤與收縮所產生之應力變化亦造成電極與膜材分離的現象。

關鍵字

高溫複合膜 ； 老化診斷 ； 老化機制 ； 加速老化

並列摘要

Home made Nafion composite membranes were studied for long-term operation under constant current mode at 120℃ as a control. The same MEA was also aged under cyclic humidity and current loading conditions. The stability, durability and degradation behavior of the composite membrane is investigated in detail by using “In-situ”and “Ex-situ”diagnostics. Electrochemical test methods (linear sweep voltammetry, cyclic voltammetry and polarization curves) and AC impedance analysis were performed as diagnostic tools to understand materials changes occurring during accelerated aging test. Post mortem analyses like scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffractometer (XRD) were also performed to verify the material structure degradation mechanism.

並列關鍵字

Composite Membrane ； Diagnostic Tools ； Degradation Mechanism ； Accelerated Test

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