In situ current distribution measurements in polymer electrolyte fuel cells

There has been much recent interest and development of methods to accurately measure the current distribution in an operating polymer electrolyte fuel cell (PEFC). This paper presents results from a novel technique that uses a segmented flow field with standard, nonaltered membrane electrode assemblies and gas diffusion layers. Multiple current measurements are taken simultaneously with a multichannel potentiostat, providing high-resolution temporal and spatial distribution data. Current distribution data are shown that display the distributed effects of cathode stoichiometry variation and transient flooding on local current density. It is shown that the time scale for liquid accumulation in gas diffusion layer pores is much greater than that of any electrochemical or gas-phase species transport process. In order to facilitate state-of-the-art PEFC model validation, an idealized single-pass serpentine flow field was used, and the exact geometry is presented.