The gas diffusion layer (GDL), one of the essential components of the membrane electrode assembly (MEA), plays an important role in the performance of proton exchange membrane fuel cells. With respect to this essential component and its specifications, this work intends to examine the impact of GDL defects and their effects on cell performance for component quality control. To understand how GDL defect affects its performance and to what level the defect takes effect, ex situ characterization and in situ fuel cell testing are conducted by comparing pristine and defective GDLs. While ex situ GDL properties incorporate measurements of thickness, conductivity, and permeability under compression, in situ investigation mainly involves polarization curve and electrochemical impedance spectroscopy. Among different types of GDL defects, pinholes are targeted in this work. As such, the evaluation focuses on assessing the effects of varying numbers and sizes of pinhole defects under different relative humidities (RHs). Using the state‐of‐the‐art GDLs, an improved cell performance is observed with defective GDLs (evenly distributed 40 pinholes with a diameter of 0.58 mm) under 100% RH. Results also show that the effect of pinhole defects is sensitive to RH, as well as operating current densities.

中文翻译：

---

研究气体扩散层中的针孔缺陷以控制质子交换膜燃料电池的质量

气体扩散层（GDL）是膜电极组件（MEA）的重要组成部分之一，对质子交换膜燃料电池的性能起着重要作用。对于这一重要组件及其规格，本工作旨在研究 GDL 缺陷的影响及其对电池性能的影响，以实现组件质量控制。为了了解 GDL 缺陷如何影响其性能以及缺陷影响的程度，通过比较原始和有缺陷的 GDL 进行异位表征和原位燃料电池测试。非原位 GDL 特性包括压缩下厚度、电导率和渗透率的测量，而原位研究主要涉及极化曲线和电化学阻抗谱。在不同类型的 GDL 缺陷中，针孔是本工作的目标。因此，评估的重点是评估不同数量和尺寸的针孔缺陷在不同相对湿度 (RH) 下的影响。使用最先进的 GDL，在 100% RH 下观察到有缺陷的 GDL（均匀分布的 40 个直径为 0.58 mm 的针孔）的电池性能得到改善。结果还表明，针孔缺陷的影响对相对湿度以及工作电流密度很敏感。