High-Resolution Visualization of Water Accumulation Behavior in an Operating PEMFC by Soft X-ray Radiography

Abstract

A carbon-cloth gas diffusion layer (GDL) displays better performance than a carbon-paper GDL under humidified condition. To investigate the relationship between GDL micro-structure and liquid water transport phenomena, water accumulation behavior in an operating Proton Exchange Membrane Fuel Cell (PEMFC) was visualized by soft X-ray radiography. Utilization of the soft X-ray range made it possible to visualize the liquid water in a PEMFC with the spatial resolution of 0.5 um and temporal resolution of 1.0 sec/frame. The water accumulated in a carbon-cloth GDL was locally distributed, and a larger amount of water accumulated in it than in a carbon-paper GDL. These results suggested that the broader pore distribution creates oxygen transport paths even if water accumulates in the GDL, and the pore structure has great importance. Furthermore, to investigate liquid water transport in more detail, stereoscopy technique has developed to get three-dimensional information with high temporal and spatial resolution.