The wet domain in a microporous layer (MPL) in a polymer electrolyte fuel cell (PEFC) was visualized in order to clarify water accumulation in the MPL. The performance of PEFC is affected by accumulation of liquid water in the cathode gas diffusion layer (GDL). The liquid water hinders oxygen transport to the catalyst layer, resulting in increased mass-transport loss. Although MPLs suppress water accumulation in the GDL, this mechanism has not yet been fully clarified. The present study used synchrotron X-ray micro computed tomography (CT) to visualize water accumulation in the MPL. The experiment was conducted while supplying water vapor to the MPL side of the GDL. The MPL was visualized to be wetted heterogeneously, and liquid water movement from the MPL to the GDL substrate was visualized. These observations were supported by plotting the volume fraction of either the wet domain of the MPL or the water cluster as a function of through-plane distance.

可视化聚合物电解质燃料电池（PEFC）中微孔层（MPL）中的湿区，以阐明MPL中的水积聚。PEFC的性能受液态水在阴极气体扩散层（GDL）中的积累的影响。液态水阻碍了氧气向催化剂层的传输，导致传质损失增加。尽管MPL抑制了GDL中的水积聚，但这种机理尚未完全阐明。本研究使用同步加速器X射线微计算机断层扫描（CT）可视化MPL中的水积聚。在向GDL的MPL侧供应水蒸气的同时进行了实验。观察到MPL被异质地润湿，并且观察到了从MPL到GDL底物的液态水运动。