Umicore Ag & Co Kg

Sandra Wittpahl

Ralf Zuber

Klaus Schaack

Joachim Köhler

Holger Dziallas

Karl-Anton Starz

Peter Seipel

Joachim Kohler

Knut Fehl

Anita Krämer

Lutz Rohland

Pia Braun

Markus Maier

Alexander Kabza

Anita Kramer

Manfred Diehl

Joachim Koehler

Christian Eickes

Günther Vulpius

Bernd Dillmann

Markus Maler

The present invention relates to the field of electrochemical cells and fuel cells, and more specifically to polymer-electrolyte-membrane fuel cells (PEMFC) and direct methanol fuel cells (DMFC). It is directed to catalyst-coated ionomer membranes ('CCMs') and membrane-electrode-assemblies ('MEAs') that contain one or more protective film layers for protection, sealing and better handling purposes. The one or more protective film layers are attached to the surface of said catalyst-coated membranes in such a way that they overlap with a region of the passive non-coated ionomer area, and with a region of the active area that is coated with a catalyst layer. Furthermore, the present invention discloses a process for manufacture of CCMs and MEAs that contain protective film layers. The materials may be used as components for the manufacture of low temperature fuel cell stacks.

Process for manufacturing a catalyst-coated ionomer membrane with protective film layer

The invention relates to a membrane electrode unit (MEU) for electrochemical apparatuses, in particular for direct methanol fuel cells (DMFC). The membrane electrode unit contains backings (i.e. gas diffusion layers) on the anode side and cathode side, which have a different water tightness (WT). The anode backing must have a lower water tightness (i.e. a higher water permeability) than the cathode backing, where WT&#x3c;WT. The anode backing preferably has no compensating layer (microlayer), has a lower content of water repellent (from 2 to 10 wt.-%, based on the total weight) and has a higher total pore volume (VTot) than the cathode backing. The membrane electrode units produced have a substantially improved performance in DMFC fuel cells which are operated with aqueous methanol solution.

Membrane-electrode unit for direct methanol fuel cells (DMFC)

The invention relates to a membrane-electrode assembly (MEA) for electrochemical devices, in particular for membrane fuel cells. The membrane-electrode assembly has a semi-coextensive design and comprises an ion-conducting membrane, two catalyst layers and gas diffusion layers of differing sizes on the front side and rear side. The first gas diffusion layer has smaller planar dimensions than the ion-conducting membrane, while the second gas diffusion layer has essentially the same planar dimensions as the ion-conducting membrane. As a result, the ion-conducting membrane has a surface which is not supported by a gas diffusion layer on the front side. The membrane-electrode assembly has, owing to the particular construction, a stable structure which can be handled readily and displays advantages in the sealing of the reactive gases from one another and also in terms of the electrical properties. In particular, the hydrogen penetration current is significantly reduced. New processes for producing the MEA of the invention are described, in particular the method of heat pulse welding. The membrane-electrode assembly is used in PEM fuel cells, direct methanol fuel cells, electrolysers and other electrochemical devices.

Membrane electrode assembly for use in electrochemical devices

The invention relates to membrane-electrode assemblies for the electrolysis of water (electrolysis MEAs), which contain an ion-conducting membrane having a front and rear side; a first catalyst layer on the front side; a first gas diffusion layer on the front side; a second catalyst layer on the rear side, and a second gas diffusion layer on the rear side. The first gas diffusion layer has smaller planar dimensions than the ion-conducting membrane, whereas the second gas diffusion layer has essentially the same planar dimensions as the ion-conducting membrane ('semi-coextensive design'). The MEAs also comprise an unsupported free membrane surface that yields improved adhesion properties of the sealing material. The invention also relates to a method for producing the MEA products. Pressure-resistant, gastight and cost-effective membrane-electrode assemblies are obtained, that are used in PEM water electrolyzers, regenerative fuel cells or in other electrochemical devices.

Membrane electrode unit for the electrolysis of water

Catalyst-coated ionomer membrane with protective film layer and membrane-electrode-assembly made thereof

An ink is disclosed for producing membrane electrode assemblies for fuel cells which contains a catalyst material, an ionomer, water and an organic solvent. The ink is characterized in that the organic solvent is at least one compound from the group of linear dialcohols with a flash point higher than 100&#xb0; C. and is present in the ink in a concentration between 1 and 50 wt. %, with respect to the weight of water.

Ink for producing membrane electrode assemblies for fuel cells

The present invention relates to the field of electrochemical cells and fuel cells, more specifically to polymer-electrolyte-membrane (PEM) fuel cells and describes a process for the manufacture of membrane-electrode-assemblies (MEAs) containing five layers. The five-layer MEA is assembled together by means of a lamination process involving an adhesive component. The anode gas diffusion layer, the catalyst-coated membrane and the cathode gas diffusion layer are combined together by a low temperature/low pressure lamination process. Handling of the MEAs and assembly of the products into PEMFC and DMFC stacks is simplified. Less damage and perforation of the catalyst-coated membrane occurs and thus the performance of the five-layer MEAs is significantly improved.

Process for the manufacture of membrane-electrode-assemblies using catalyst-coated membranes

The present invention relates to a method for the production of a membrane electrode assembly comprising a polymer electrolyte membrane with two opposing membrane surfaces and a cathode and an anode electrode each comprising a catalyst layer and a gas distribution layer. Each catalyst layer is interposed between a membrane surface and the corresponding gas distribution layer. The catalyst layer of the cathode and/or the catalyst layer of the anode comprise at least two sub-layers. According to the present invention at least one of the sub-layers of the cathode electrode and/or the anode electrode is applied directly to the surface of the membrane while the remaining sub-layers are applied to the corresponding gas distribution layers. Finally the assembly of the coated membrane and the coated gas distribution layers is produced.

Method for the production of membrane electrode assemblies for fuel cells

A process for producing a membrane electrode assembly for fuel cells containing a polymer electrolyte membrane having a first and a second surface parallel to each other. The first surface forms a firm composite with a first catalyst layer and a first water repellent gas distribution layer and said second surface form a firm composite with a second catalyst layer and a second water repellent gas distribution layer. The catalyst layers are prepared by using inks containing electrocatalysts, one or more solvents, proton-conducting ionomer and optionally water repelling agents and pore-forming agents. In the process the two catalyst layers are applied to or contacted with the respective surfaces of the polymer electrolyte membrane successively, wherein during the application or contacting process to one surface always the opposite surface of the membrane is supported.

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Obertshausen, Germany

Sandra Wittpahl