Influence of water transport properties through gas diffusion layer on flooding in PEFC

Abstract

How the property of liquid water transport through a gas diffusion layer (GDL) influences the cell performance on electrode flooding was investigated by examining the cell performance and measuring the pressure to dehydrate liquid water from a GDL on a polymer electrolyte fuel cell (PEFC). A PEFC is required to operate under high humidity condition and high gas utilization aimed at high performance and high system efficiency. However, conversely, sudden decrease of the cell performance is caused by the water flooding in some types of GDL which disturbs the gas diffusion to reaction area under above conditions. The GDLs fabricated by four manufacturers which have different characters of structure, affinities for water, with and without through-holes, with and without a water management layer were examined by the single cell generation examination. Focusing attention on the experimental fact of the recent researches, the GDL is impregnated with water when electrode flooding is caused. As the examination outside of the cell that imitates the actual generation, the property of liquid water transport was evaluated by measuring dehydration pressure of through plane direction from water impregnated GDL. By the comparison limiting current determined by the IV curve with dehydration pressure, it was found that strong negative correlation existed between flooding phenomena in the GDL and pressure to dehydrate from the GDL.