固体高分子形燃料電池内の水分布の可視化と電気化学特性に関する研究

抄録

To evaluate the water-accumulation phenomena and electrochemical characteristics in an operating polymer electrolyte fuel cell (PEFC), simultaneous measurements of water distribution in the through-plane direction and the electrical impedance were carried out by using a neutron radiography and electro-chemical impedance spectroscopy. The water distributions were obtained every 60 sec after the power generation, and the two-dimensional water distributions were compared with the proton exchange membrane (PEM) and the reaction resistances. Change in conditions of power generation, geometry of the gas channel and with or without micro porous layer (MPL) affected the water accumulation in the PEFC. The PEM resistance decreased with increasing the water saturation in the membrane at the beginning of the power generation. Reaction resistance increased with the liquid water in the gas diffusion layer (GDL) and the gas channels. Therefore, rapid increases of the reaction resistance were confirmed at higher current density. We also evaluated the correlation between ion conductivity and membrane resistance. Ion conductivity increased with water content in the PEM. However, the membrane resistance was less affected by the water contents at low range of the water content in comparison to the Springer’s model.