Transient and steady state current density distribution measurements in a polymer electrolyte fuel cell

There has been much recent interest and development in methods to accurately measure the current distribution in an operating polymer electrolyte fuel cell. This paper presents results from a novel technique that uses a segmented flow field with standard, non-altered membrane electrode assemblies and gas diffusion layers. Multiple current measurements are taken simultaneously with a multi-channel potentiostat, providing high-precision temporal and spatial distribution data. Current distribution data are shown over a wide variety of test conditions with significant variations across the fuel cell. In addition, the effects of cathode flooding and pore filling with time are investigated, and it is shown that the time scale for liquid accumulation in gas diffusion layer pores is much greater than that of any electrochemical process or gas-phase species transport. In order to facilitate state-of-the-art polymer electrolyte fuel cell (PEFC) model validation, an idealized single-pass serpentine flow field was used, and the exact geometry is presented.