Characteristics of moisture distribution and mass transfer in MPL by neutron radiography

Mass transfer characteristics of gas diffusion layer (GDL) are closely related to cell performance in polymer electrolyte fuel cell (PEFC). It is important to illustrate the water behavior in MPL for improving cell performance in operation. Because MPL is adjacent to catalyst layer and GDL substrate, supposedly influences their liquid water behavior. The paper with MPL was evaluated as specimen GDL. The images of liquid water distribution in the GDL were taken by neutron radiography under a few experimental conditions in order to elucidate the characteristics of water behavior in MPL. The images reveal that neutron radiography can be used to analyze the water behavior in MPL as an effective tool. It is clarified ; MPL has two aspects, that is, one aspect is that the water retentivity and nature of network between MPL and paper substrate are formed under partiallysaturated condition, another is that MPL acts as hydrophobic under dry condition.