Investigation of Water Distribution in a Polymer Electrolyte Fuel Cell Using X-Ray Imaging Technique

Abstract

Water management in a polymer electrolyte fuel cell (PEFC) was experimentally investigated using an X-ray microscopy technique. Recently, fuel cell has been receiving large attention as an important renewable energy due to its efficiency, clearness and sustainability. Among various types of fuel cells, PEFC can be used as a power source of transport vehicles and home applications. In recent commercial development of PEFC, water management is one of the major problems to be solved. In fact, proper water management is vital to enhance performance and durability of PEFC. In this study, transport of water inside MEA (membrane electrode assembly) and GDL (gas diffusion layer) layers of an operating (in situ) fuel cell was observed using the synchrotron X-ray micro-imaging technique. As the synchrotron X-ray imaging technique has very high spatial and temporal resolutions, it is suitable for observing the dynamic movement and behavior of liquid layer and water distribution inside the PEFC. For this X-ray micro-imaging experiment, a single cell test kit of PEFC was specially designed for convenient capturing of X-ray images. Temporal variation of gray level in the PEFC components, such as MEA, GDL and endplate, was investigated with varying loading condition. As a result, X-ray images of the PEFC components were clearly distinguished by image pattern and gray level difference. The gray level shows roughly symmetric distribution with respect to MEA layer. The gray level at GDL decreases with lapse of time, indicating the increase of H2O concentration with time.