Effect of MPL with a hydrophilic layer on water distribution and oxygen transport resistance in PEFC

To enhance oxygen transport in polymer electrolyte fuel cells, a microporous layer (MPL) with a carbon-fiber hydrophilic layer is developed. Polarization curves show that applying a hydrophilic layer to the MPL increases power output under wet conditions. An extended limiting current analysis by authors suggests that the hydrophilic layer suppresses an increase in the oxygen transport resistance inside the catalyst layer (CL). The observation of water distributions by a freezing method and cryo-SEM shows that there is small ice in the hydrophilic layer, while thick ice layer at the MPL/CL interface without the hydrophilic layer. A hydrophilic layer could improve oxygen transport by suppressing water accumulation at the interface.