Small-angle neutron scattering study on membrane electrolyte assembly in operating polymer electrolyte fuel cell; Using deuterium gas for contrast variation method

作動状態下の固体高分子形燃料電池の膜電極接合体に関する中性子小角散乱測定; 重水素ガスを用いたコントラスト変調

Putra, A.; 山口 大輔; Zhao, Y.; 小泉 智

Putra, A.; Yamaguchi, Daisuke; Zhao, Y.; Koizumi, Satoshi

SANS was used to study the ionomer and water on the MEA in operating PEFC. We employed H and D gas as a fuel for operation. With exchange of H and D, we aim to perform a contrast variation as for polyelectrolyte film. By changing a fuel gas from H to D, SANS quantitatively detected decrease of scattering intensity at scattering maximum originating from the ion-channel in the electrolyte. After quantitative analyses on scattering intensity, which is related to water ratio (HO/DO) in the ion channel, we found that 30% (wt) of the total water is replaced by DO by changing the gas from H to D. In a stationary state of fuel cell operation using D, the scattering intensity rhythmically oscillates. The rhythmic oscillation found for the peak intensity is a non-equilibrium and non-linear phenomenon, in which flooding in a flow field is a feedback mechanism to slow down chemical reaction or water production by affecting mass transportation of air at the cathode.