Membrane electrode assembly Subject

Schematic illustration of the membrane electrode assembly (MEA) of a PEM fuel cell (top) and details which have been subjected to modeling and simulation work described in the following chapters. Atomic level simulations have been performed for water and proton transport within the hydrophilic domaine of hydrated ionomers and for the electrochemical processes taking place at the electrocatalysts surfaces. The latter include the introduction of polarizable solvents and electrostatic potential variations. Mesoscale modeling is aiming at a better description and understanding of the development of ionomer microstructures.

For further improvement in the catalyst-membrane contact, the membrane is sandwiched between the electrodes, with the active layers facing the membrane and subjected to hot pressing at a temperature of 130 to 155°C, pressures up to 100 bar, and pressing times of 1 to 5 minutes. This operation yields unique membrane-electrode assemblies (MEAs). 

Fig. 1 Cross-sectional electron microprobe images of four locations of a membrane electrode assembly (MEA) from a polymer-electrolyte fuel cell (PEFC) stack that was subjected to 1,994 uncontrolled start/stop cycles. The stack utilized two fuel passes, as shown. As expected by the reverse-current mechanism, the amount of damage depends on the distance from the fuel inlet. Note the changes in the cathode catalyst layer and the presence of platinum in the membrane, especially in the second pass...

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