Two high temperature polymer exchange membrane fuel cells (HT-PEM FCs) were operated under repeated starvation/regeneration steps for 550 min (DPS-1) and 12 days (DPS-2). Concerning the investigation of the irreversible degradation under fuel (H₂) starvation the focus was put on the electrochemical characteristics during regeneration, since during this step the system operates under normal conditions. Electrochemical impedance spectroscopy (EIS) and distribution of relaxation times (DRT) analysis were used as electrochemical characterization methods. DRT analysis of selected impedance spectra during regeneration steps for the first seven days revealed an intensity increase of the charge transfer kinetics of the cathode (ca. 10 Hz) and the anode (ca. 100 Hz). From day 3 on, an additional peak at 300–800 Hz appeared likely pointing to the formation of surface oxides at the anode side. The EIS and DRT results were verified with Focused Ion Beam-Scanning Electron Microscopy (FIB-SEM), Microcomputed Tomography (μ-CT) and Transmission Electron Microscopy (TEM). While TEM indicated advanced Pt particle agglomeration pointing to carbon corrosion, μ-CT measurements showed an increase of void volume fraction and a decrease of the tortuosity value. The combined results show that the anode gas outlet region of the FC is more degraded than the inlet region.

两个高温聚合物交换膜燃料电池（HT-PEM FC）在重复的饥饿/再生步骤下运行550分钟（DPS-1）和12天（DPS-2）。关于对燃料（H _2）下不可逆降解的研究由于系统在正常条件下运行，因此在再生过程中将重点放在电化学特性上。电化学阻抗谱（EIS）和弛豫时间分布（DRT）分析被用作电化学表征方法。在最初的7天的再生步骤中，选定阻抗谱的DRT分析表明，阴极（约10 Hz）和阳极（约100 Hz）的电荷转移动力学强度增加。从第3天开始，在300-800 Hz处出现了另一个峰值，可能表明在阳极侧形成了表面氧化物。EIS和DRT结果通过聚焦离子束扫描电子显微镜（FIB-SEM），微计算机断层扫描（μ-CT）和透射电子显微镜（TEM）进行了验证。TEM显示，Pt颗粒的聚集趋向于碳腐蚀，而μ-CT测量显示空隙体积分数增加，而曲折度值减小。组合结果表明，FC的阳极气体出口区域比入口区域的退化程度更大。