Flooding and performance of polymer electrolyte fuel cell, investigated by small-angle neutron scattering, neutron radiography and segmented electrode

Publication date: March 2019Source: Results in Physics, Volume 12Author(s): Satoru Ueda, Satoshi Koizumi, Yasuyuki TsutsumiAbstractIn order to elucidate the cell performance related to swelling or flooding of the polymer electrolyte membrane (Nafion®), we performed in-situ measurements of small-angle neutron scattering (SANS) and neutron radiography (NR) for a polymer electrolyte fuel cell (PEFC) during electricity generation. SANS determined the swelling behavior by observing inter-particle scattering of water-clusters and mean inter-distance of nm order (Lw). With increased current density, Lw heterogeneously increases along the serpentine-shaped gas channel. NR revealed that flooding occurs along the channel after reaching Lw to the maximum. Lw determined by SANS was converted to the number of water molecules (λw) hydrating around a sulfonic group. Using this key value, we evaluated the membrane resistance Rm. To determine the local cell performance, corresponding to SANS & NR observations, we developed a segmented electrode cell combining electrochemical impedance spectroscopy. The segmented electrode independently determined the membrane resistance and I-V curve were determined for the local area, which is sensitive to the heterogeneous swelling along a film thickness. As a result of comparison with SANS and the results by segmented electrode, we found heterogeneous swelling along the gas flow path or along a thickness direction. The heterogeneity changes as the curren...

Source: Results in Physics - December 9, 2018 Category: Physics Source Type: research