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EP-4736250-A1 - METHOD OF PRODUCING A MEMBRANE-ELECTRODE ASSEMBLY USING AN ADHESIVE FILM IN ORDER TO DIMENSIONALLY STABILIZE THE POLYMER MEMBRANE

EP4736250A1EP 4736250 A1EP4736250 A1EP 4736250A1EP-4736250-A1

Abstract

The invention relates to a method of producing a membrane-electrode assembly for a fuel cell and/or electrolysis cell. This involves providing a polymer membrane based on hydrocarbon ionomers and comprising a front side and reverse side. There is a carrier film on the reverse side of the polymer membrane, and a first catalyst layer has been applied to the front side. The carrier film is removed, such that the reverse side of the polymer membrane is freely accessible. An adhesive film is applied to the first catalyst layer, so as to enable stabilization for the coating of the reverse side with a second catalyst layer. The invention further relates to a membrane-electrode assembly producible by the method of the invention.

Inventors

  • LOMBECK, Florian
  • EDELMANN, JOCHEN

Assignees

  • ionysis GmbH

Dates

Publication Date
20260506
Application Date
20240626

Claims (15)

  1. 1. A method for producing a membrane electrode unit for a fuel cell and/or an electrolysis cell, comprising the following steps: a) providing a polymer membrane (1) based on hydrocarbon ionomers comprising a front side and a back side, wherein a carrier film (5) is present on the back side and a first catalyst layer (3) is present on the front side, b) removing the carrier film (5) so that the back side of the polymer membrane (1) is freely accessible, c) applying an adhesive film (7) to the front-side, first catalyst layer (3), d) coating a second catalyst layer (9) on the back side of the polymer membrane (1).
  2. 2. Method according to the preceding claim, characterized in that the adhesive film (7) contacts the polymer membrane (1) with an adhesive force of 0.1 - 10 cN/mm, preferably 0.5 - 5 cN/mm, particularly preferably 1 - 3 cN/mm.
  3. 3. Method according to one or more of the preceding claims, characterized in that the adhesive film (7) has a multi-layer structure and comprises a substrate and an adhesive layer, wherein during the application of the adhesive film (7) its adhesive layer comes into contact with the first catalyst layer (3).
  4. 4. Method according to the preceding claim, characterized in that the substrate is selected from a group of polyesters - preferably polyethylene terephthalate, polyethylene naphthalate - or from a group of polyolefins, preferably polyethylene, polypropylene or a group of polyimides and/or polyamides, polyvinyl chloride and/or the adhesive layer is formed by an adhesive material selected from a group comprising an acrylate, rubber and/or silicone.
  5. 5. Method according to one or more of the preceding claims, characterized in that the adhesive film (7) has a thickness of 10 pm - 1 mm, preferably 20 pm - 500 pm, particularly preferably 40 pm - 200 pm.
  6. 6. Method according to one or more of the preceding claims, characterized in that the adhesive film (7) is removed after coating the second catalyst layer (9) and/or is wound up on a winding roll for recycling.
  7. 7. Method according to one or more of the preceding claims, characterized in that TI the adhesive film (7) has a protective film, wherein the protective film is removed before the adhesive film is applied to the first catalyst layer.
  8. 8. Method according to one or more of the preceding claims, characterized in that the method is carried out via a roll-to-roll process, wherein the adhesive film (7) is preferably applied to the first catalyst layer (3) via a coating roll and a coating of the second catalyst layer (9) is subsequently carried out while the polymer membrane (1) is still guided along the coating roll.
  9. 9. Method according to one or more of the preceding claims, characterized in that the coating of a second catalyst layer (9) is carried out using a coating method selected from a group comprising slot die coating, spray coating, screen printing method, doctor blade coating, and/or gravure printing method, wherein a slot die coating is particularly preferably used.
  10. 10. Method according to one or more of the preceding claims, characterized in that the second catalyst layer (9) is dried after coating on the polymer membrane (1) using a drying method, wherein the drying method is preferably selected from a group comprising hot air drying, infrared drying, plasma drying and/or contact drying, wherein preferably a drying time between 1 - 30 min, preferably between 1 - 5 min, particularly preferably between 1 - 4 min and/or a temperature between 20°C - 150°C, preferably between 20°C - 100°C is used.
  11. 11. Method according to one or more of the preceding claims, characterized in that the polymer membrane (1) based on the hydrocarbon ionomers is free of perfluorinated sulfonic acids, preferably substantially fluorine-free.
  12. 12. Method according to one or more of the preceding claims, characterized in that the first and/or second catalyst layer (9) is coated as a disperse liquid onto the polymer membrane (1).
  13. 13. Method according to one or more of the preceding claims, characterized in that a catalyst ink is provided for the coating of the first and/or second catalyst layer (9), wherein the catalyst ink preferably comprises a Catalyst material which is bound to a carrier material, comprises a solvent and/or a binder material, wherein preferably the catalyst material comprises a material selected from a Group comprising platinum, ruthenium, rhodium, iridium, palladium, gold, silver, chromium, manganese, copper, cobalt, nickel, iron, molybdenum and/or yttrium, wherein preferably the solvent comprises a material selected from a group comprising water, an organic solvent, preferably ethanol, propanol and/or butanol as well as solvent mixtures, wherein preferably the carrier material comprises carbon, preferably in graphite form.
  14. 14. Membrane electrode assembly producible by a method according to one or more of the preceding claims.
  15. 15. Use of a membrane electrode assembly according to the preceding claim for electrochemical applications, preferably selected from a group comprising Hydrogen fuel cells, electrolysis cells, power-to-X applications, especially for CO2 electrolysis and/or ammonia electrolysis.

Description

MANUFACTURING METHOD OF A MEMBRANE-ELECTRODE UNIT USING AN ADHESIVE FILM FOR SHAPE STABILIZATION OF THE POLYMER MEMBRANE DESCRIPTION The invention relates to a method for producing a membrane electrode assembly for a fuel cell and/or electrolysis cell. A polymer membrane based on hydrocarbon ionomers is provided, which comprises a front and a back. A carrier film is present on the back of the polymer membrane and a first catalyst layer is attached to the front. The carrier film is removed so that the back of the polymer membrane is freely accessible. An adhesive film is applied to the first catalyst layer, enabling stabilization for coating the back with a second catalyst layer. Furthermore, the invention relates to a membrane electrode assembly which can be produced by the method according to the invention. Background and State of the Art In membrane-based hydrogen technologies, ^-fuel cells and/or in water electrolysis, so-called CCMs (catalyst-coated membranes), also known as membrane electrode assemblies (MEAs), are used as a central component. They can also be used in other technologies, such as Power-to-X applications. A CCM or MEA is a membrane coated with electrodes on both sides. The membrane separates the anode and cathode sides of the CCM or MEA and is selectively permeable (in the case of anion exchange membranes, AEM) to only negatively charged anions or (in the case of proton exchange membranes, PEM) to protons. The respective chemical redox reactions take place in the electrode layers. A low resistance at the respective boundary layers, i.e. the resistance of the electrodes, is essential for the efficient operation of the fuel cell and/or electrolysis cell. i.e. a close connection of the two electrode layers to the membrane. Due to the high importance of CCM for the operation of a fuel cell, there are also a variety of approaches in the state of the art to offer advantageous process technologies for their production. The technologies in this regard must take several factors into account in order to be able to guarantee safe production and reliable functionality. The low layer thickness of the polymer membrane is a relevant factor, which must have the necessary stability for use in a fuel cell or electrolysis cell. However, coating a polymer membrane with catalyst layers with such a low thickness is not trivial. Applying the catalyst layer can lead to deformation and/or swelling of the membrane, which in turn would be disadvantageous for use in the fuel cell, as an inhomogeneous design would be achieved. Furthermore, the catalyst layer is usually liquid when coated, which makes it difficult for the catalyst layer to adhere to the membrane. A proven manufacturing process for a CCM in the state of the art is the so-called decal process. In the decal process, a catalyst dispersion is usually coated onto a carrier film or decal film (or just decal) and dried. This creates an anode electrode or ACD (anode coated decal) and a cathode electrode. A composite comprising a polymer membrane and a cathode is applied to the anode electrode using a pressing process, e.g. by lamination. After pressing, the decal film is removed. After the decal film has been removed, a polymer membrane or CCM coated on both sides with catalyst or electrode material is created. In the state of the art, various variants of a basic decal process as well as alternative approaches, for example by means of a direct coating of catalyst material on polymer membranes, are known in order to be able to produce catalyst-coated membranes. EP 3529845 B1 discloses a method for providing a catalyst-coated membrane for a fuel cell by means of direct coating in a roll-to-roll process. A first side is coated with a catalyst layer while a carrier film supports the membrane. After the carrier film is removed, the polymer membrane is transported through a vacuum conveyor to prevent or minimize possible swelling caused by the coating of another catalyst layer. US 2002/0064593 A1 describes a method for producing a membrane electrode unit, in which the membrane is also directly coated with the catalyst layers. During the process, the opposite side of the membrane is always supported. When the polymer membrane is coated with a first catalyst layer, a support film is present on the opposite side. A gas distribution layer is then applied as a web to the (still) moist first catalyst layer. The support film is then removed and the second side of the membrane can be coated with a catalyst material, while the gas distribution layer acts as a support structure to prevent swelling. US 2022/0069325 A1 relates to a method for producing a polymer membrane which is coated with a catalyst layer. During the coating of a first side of the polymer membrane with the catalyst layer, a base material serves as a support. For the coating of the second side, the first electrode or catalyst layer itself is to serve as a support material and for this purpose comprises a bi