Fuel cell performance and durability are highly dependent on water management, wherefore wettability properties of the cell's gas diffusion layer (GDL) are important. In this work, we implement a method to determine the GDL wetted surface area, which is based on capacitance measurements by cyclic voltammetry with a pH-neutral, aqueous electrolyte, to an automotive size fuel cell failure analysis process and demonstrate its benefit. The electrolyte penetrates large pores of the GDL, wherefore, in contrast to the most conventional methods, also inner parts of the GDL are measured. Tenside concentration of the electrolyte and penetration time, polytetrafluoroethylene treatment of the GDL, and properties of the microporous layer highly influence the capacitance values. Thus, the method is sensitive to different GDL morphologies and surface modifications. Different degradation patterns for samples either artificially chemically and mechanically aged or after real-operation (e.g., prototype vehicle) are detected by the method. For a comprehensive understanding, the obtained results are compared to ex situ degradation analysis data. A comparison to static contact angle measurements, being a state-of-the-art method to determine GDL wettability, reveals a higher sensitivity of the introduced method to detect degradation, in particular, of chemically aged and real-operation aged GDLs.

中文翻译：

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循环伏安法测定汽车燃料电池气体扩散层润湿性

燃料电池的性能和耐久性高度依赖于水管理，因此电池气体扩散层 (GDL) 的润湿性很重要。在这项工作中，我们实施了一种确定 GDL 润湿表面积的方法，该方法基于使用 pH 值中性的水性电解质通过循环伏安法测量电容，用于汽车尺寸燃料电池故障分析过程并证明其益处。电解质渗透 GDL 的大孔，因此，与最传统的方法相比，还测量 GDL 的内部部分。电解质的表面浓度和渗透时间、GDL 的聚四氟乙烯处理以及微孔层的性质对电容值有很大影响。因此，该方法对不同的 GDL 形态和表面修饰敏感。该方法检测到样品经过人工化学和机械老化或实际操作后（例如原型车）的不同降解模式。为了全面理解，将获得的结果与非原位降解分析数据进行了比较。与静态接触角测量相比，这是一种确定 GDL 润湿性的最先进方法，揭示了引入的检测降解的方法具有更高的灵敏度，特别是化学老化和实际操作老化的 GDL。将获得的结果与非原位降解分析数据进行比较。与静态接触角测量相比，这是一种确定 GDL 润湿性的最先进方法，揭示了引入的检测降解的方法具有更高的灵敏度，特别是化学老化和实际操作老化的 GDL。将获得的结果与非原位降解分析数据进行比较。与静态接触角测量相比，这是一种确定 GDL 润湿性的最先进方法，揭示了引入的检测降解的方法具有更高的灵敏度，特别是化学老化和实际操作老化的 GDL。