Abstract
In situ visualization of water in an operating polymer electrolyte fuel cell (PEFC) by magnetic resonance imaging (MRI) and soft X-ray radiography (SXRG) is presented. Concept and methodologies of these techniques in order to apply water visualization in PEFCs are described. MRI measurement of a hydrated polymer electrolyte membrane in a PEFC revealed a partial dehydration of the membrane due to electro-osmotic drag under insufficient humidification, while sufficient hydration of the membrane was confirmed under fully hunridified condition. SXRG was applied to visualize spatial and temporal variation of liquid water in both catalyst layers and gas diffusion layers. In-plane and through-plane visualization of water accunlUlation and discharge behaviors was explored and revealed inhomogeneous accumulation of liquid water in a porous electrode and local discharging process through a micro-scale crack in micro-porous layer.
