Measurement of water transport properties through membrane-electrode assemblies: I. Membranes

A method using a hydrogen pumping cell to measure the electro-osmotic drag (EOD) coefficient of Gore-Select membranes is described. This technique was verified with the measurement of Nafion membranes, yielding results comparable with those reported in the literature and hence supporting its validity for various types of membranes. The EOD coefficient of Gore-Select membranes was measured to be 1.07 over the wide relative humidity range between ∼40% and 95%. An approach was also proposed to characterize the water concentration at the interface between the membrane and the cathode catalyst layer using high-frequency resistance measurement in an operating fuel cell. Based on the information of water concentrations on both sides of the membrane and the water diffusive flux across the membrane, the water diffusion coefficient of Gore-Select membranes was experimentally determined. It was found that the water diffusion coefficient of Gore-Select membranes is roughly half that of Nafion membranes based on the best fit of our available data in this work.