本研究針對純氧質子交換膜燃料電池堆於操作老化過程中的性能衰退進行探討。隨著燃料電池於高效率能源轉換與低碳應用中的重要性提升，其壽命與穩定性評估成為關鍵議題。相較於單電池，電堆更易受到氣體分配不均、溫度梯度、水管理失衡影響，導致各級單電池性能不一致，進而影響整體輸出，本研究聚焦於單電池劣化機制、電堆性能變化及各級單電池非均勻衰退行為。實驗採用 Gore M820.15 膜電極組進行單電池加速老化，並延伸至五級電堆，結合極化曲線、電化學阻抗頻譜、循環伏安法、線性掃描伏安法、空氣中斷測試及各級單電池電壓與溫度量測進行分析。 單電池老化測試結果顯示，初始狀態至 200 cycles 間性能穩定，但於 200 至 800 cycles 間快速衰退，0.6 V 下電流密度由 1314 mA/cm² 降至 426 mA/cm²。循環伏安分析顯示電化學活性表面積由 69.66 降至 2.16 m²/g，顯示 Pt 活性位點大幅流失；交流阻抗譜亦顯示歐姆阻抗與電荷轉移阻抗增加。線性掃描伏安結果未顯示氫氣crossover電流顯著上升，表示於本研究測試範圍內，膜破損並非主要失效原因；電堆老化測試結果顯示，經 1000 cycles 後，電堆於 3.0 V 下電流密度由 800.15 降至 391.29 mA cm⁻²，性能剩餘初始狀態約 49%，各級單電池電壓自 400 cycles 起逐漸分散，Cell 4 出現較低電壓，顯示電堆老化具非均勻性。 在本研究之測試範圍內，純氧質子交換膜燃料電池堆性能衰退為觸媒活性流失、阻抗增加、及單電池差異共同作用之結果，本研究可作為電堆操作條件優化與壽命評估之參考。;This study investigates the performance degradation of pure-oxygen proton exchange membrane fuel cell （PEMFC） stacks during operational aging. As fuel cells become increasingly important for high-efficiency energy conversion and low-carbon applications， the evaluation of their durability and operational stability has become a critical issue. Compared with single cells， fuel cell stacks are more susceptible to non-uniform gas distribution， temperature gradients， water-management imbalance， and assembly variations. These factors may lead to inconsistent performance among individual cells and consequently affect the overall stack output. Therefore， this study focuses on the degradation mechanisms of single cells， performance variations of the stack， and the non-uniform aging behavior of individual cells.A Gore M820.15 membrane electrode assembly was employed for accelerated aging tests of a single cell， followed by tests on a five-cell PEMFC stack. Polarization curves， electrochemical impedance spectroscopy， cyclic voltammetry， linear sweep voltammetry， air-interruption tests， and measurements of individual-cell voltage and temperature were conducted to evaluate the electrochemical characteristics and degradation behavior. The single-cell results showed stable performance from the fresh state to 200 cycles， followed by rapid degradation between 200 and 800 cycles. At 0.6 V， the current density decreased from 1314 to 426 mA cm⁻². Cyclic voltammetry analysis indicated that the electrochemically active surface area decreased from 69.66 to 2.16 m²/g， indicating substantial loss of Pt active sites. Electrochemical impedance spectroscopy further showed increases in both ohmic resistance and charge-transfer resistance. In contrast， linear sweep voltammetry did not show a significant increase in hydrogen crossover current， suggesting that membrane damage was not the dominant degradation mechanism. For the PEMFC stack， after 1000 cycles， the current density at 3.0 V decreased from 800.15 to 391.29 mA cm⁻²， corresponding to a performance retention of approximately 49%. The voltage distribution among individual cells became progressively more dispersed after 400 cycles， and Cell 4 exhibited a relatively lower voltage， indicating non-uniform degradation within the stack. Overall， the performance degradation of the pure-oxygen PEMFC stack resulted from the combined effects of catalyst activity loss， increased internal resistance and performance differences among individual cells. The results of this study provide a reference for optimizing stack operating conditions and evaluating PEMFC stack durability.
