Characterization of Polymer Electrolyte Fuel Cells by Neutron Scattering During Operation in a Segmented Electrode Cell

Small-angle neutron scattering (SANS) is a powerful technique to visualize the swelling behavior of a polymer electrolyte membrane (Nafion) during cell operation. Using a small incident beam with 10 mm in diameter, we monitored the inhomogeneous swelling and ion-cluster size distribution in a membrane along a serpentine gas flow channel as a function of current density. To determine the local cell voltage, corresponding to SANS observation, we developed a segmented electrode that was incorporated in a shunt resistance circuit. Using the segmented electrode, we quantitatively determined local cell resistance and cell voltage during operation.