Umicore Ag & Co Kg

Dmc2 Degussa Metals Catalysts Cerdec Ag

Armin Bayer

Ralf Zuber

Knut Fehl

Karl-Anton Starz

Thomas Lehmann

Joachim Köhler

Udo Stenke

Anita Krämer

Heike K&uuml;hnhold

Volker B&auml;nisch

The invention comprises a process for making a membrane electrode assembly comprising a polymer electrolyte membrane having two opposite faces, on each face of which is applied a catalyst layer and a gas distribution layer. The two gas distribution layers in the membrane electrode assembly are formed by hydrophobized carbon substrates which, using appropriate inks containing at least one catalyst, dissolved ionomer and solvent, are each coated with a catalyst layer and are then laid on opposite faces of the polymer electrolyte membrane with the catalyst layers still in the moist state. Afterwards, a firm bond between electrolyte membrane, catalyst layers and carbon substrates is produced by treating the membrane electrode assembly at elevated temperature under pressure.

Process for producing a membrane electrode assembly and the membrane electrode assembly produced thereby

A gas diffusion structure for polymer electrolyte fuel cells having a sheet-like carbon substrate made hydrophobic and having two main opposing surfaces and a contact layer on one of these surfaces. The contact layer is formed of an intimate mixture of at least one hydrophobic polymer, which can be polyethylene, polypropylene or polytetrafluoroethylene, and finely divided carbon particles, wherein the weight percentage of the carbon particles relative to the total weight of the contact layer amounts to 40 to 90 wt. %. The gas diffusion structure is a carbon substrate made hydrophobic by at least one hydrophobic polymer and the hydrophobic polymers are restricted to two layers extending from both opposing surfaces into the carbon substrate down to a depth of from 5 to 40 &mgr;m and the hydrophobic polymers fill of from 20 to 60% of the pore volume within those layers.

Gas diffusion structures and gas diffusion electrodes for polymer electrolyte fuel cells

A PEM fuel cell stack including one or more fuel cells ( ) arranged on top of one another, each of which contains a membrane electrode assembly ( ) between two electrically conductive bipolar plates ( ), the surfaces of which are equipped with flow channels ( ) open on one side for the supply of reactive gases, whereby the membrane electrode assemblies each comprise a polymer electrolyte membrane ( ), both sides of which are in contact with a reaction layer ( ), whereby the surface area of the reaction layers is smaller than that of the polymer electrolyte membrane and a compressible, coarse-pore gas distribution layer ( ) made from carbon fiber fabric is inserted between each reaction layer and the adjacent bipolar plates congruent to the reaction lawyers along with seals ( ) in the area outside the surface covered by the gas distribution layers, whereby the gas distribution layers in the no-load condition display a thickness D and the seals a thickness D . The PEM fuel cell stack is featured by the gas distribution layers in the PEM fuel cell stack being compressed to 25 to 60% of the original thickness.

PEM fuel cell stack

Growing community of inventors

Freigericht, Germany

Armin Bayer