| 摘要: | 本研究針對質子交換膜燃料電池於純氧供應環境下之性能與耐久性進行系統性評估，特別聚焦於不同厚度之膜電極組在動態負載循環條件下的劣化機制與性能衰退行為。實驗選用Nafion系列膜材（NR211、NR212、N115與N117），結合極化曲線、電化學阻抗分析、循環伏安法、線性掃描伏安法與紅外線熱成像等多元診斷技術，從多個面向探討膜電極組的電化學特性變化與老化過程。
研究結果顯示，Nafion NR211 雖具備最佳初期性能與最低的歐姆阻抗，但在1500 cycles後即出現氫氣crossover 電流暴增、觸媒活性面積急遽下降、電荷轉移阻抗明顯上升與明顯熱點生成現象，為劣化速度最快之膜材。Nafion N117 具最厚膜厚與最低的初期氫氣 crossover 電流，但因長期操作於低電壓區間以及厚膜導致水分擴散與回復速度較慢，易在動態負載過程中產生不均勻脫水與水分積累，導致在1000 cycles後性能明顯衰退，主因為觸媒活性面積快速流失所致。Nafion N115 則在性能與長期穩定性之間取得平衡，在3500 cycles時氫氣crossover電流與電荷轉移阻抗劣化幅度最小，且未出現熱點，顯示其膜結構完整與耐久性最佳。Nafion NR212 雖然也維持較緩之性能衰退，但在 3500 cycles 時亦出現氫氣 crossover 電流急遽上升、熱點生成以及 Rct 大幅增加的現象，顯示其膜結構已遭到破壞。
整體而言，Nafion N115 在本研究純氧與動態負載循環條件下於性能與壽命兩方面皆展現最穩定表現，為具應用潛力之膜材。研究結果可作為未來高氧環境下質子交換膜燃料電池膜材選型與耐久性預測的重要參考依據。
;This study presents a systematic evaluation of the performance and durability of proton exchange membrane fuel cells (PEMFCs) under pure oxygen supply, with a particular focus on the degradation mechanisms and performance decline of membrane electrode assemblies (MEAs) with varying membrane thicknesses under dynamic load cycling conditions. Nafion series membranes (NR211, NR212, N115, and N117) were selected for investigation. A combination of diagnostic techniques—including polarization curves, electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), linear sweep voltammetry (LSV), and infrared thermal imaging—was employed to comprehensively analyze the electrochemical behavior and aging processes of the MEAs.
The results show that while Nafion NR211 exhibited the best initial performance and lowest ohmic resistance, it also degraded the fastest, with a sharp increase in hydrogen crossover current, rapid decline in electrochemical surface area (ECSA), significant rise in charge transfer resistance (Rct), and clear hotspot formation observed after 1500 cycles. Nafion N117, despite having the thickest membrane and lowest initial crossover current, suffered from pronounced performance degradation after 1000 cycles. This was mainly attributed to slow water transport and redistribution within the thick membrane, which led to uneven dehydration and water accumulation under dynamic loading, ultimately causing rapid loss of catalytic activity. In contrast, Nafion N115 achieved a favorable balance between initial performance and long-term stability. After 3500 cycles, it showed the lowest increases in crossover current and Rct, with no hotspot formation, indicating superior structural integrity and durability. Nafion NR212 maintained moderate performance stability during the early stages but eventually exhibited a sudden rise in crossover current, hotspot formation, and a significant increase in Rct at 3500 cycles, suggesting membrane structural failure.
Overall, Nafion N115 demonstrated the most stable performance and durability under the pure oxygen and dynamic cycling conditions of this study, making it the most promising membrane material for long-term PEMFC operation. These findings provide important insights for membrane selection and durability prediction in high-oxygen PEMFC applications. |
