Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M8/00—Fuel cells; Manufacture thereof
  • H01M8/02—Details
  • H01M8/0271—Sealing or supporting means around electrodes, matrices or membranes
  • H01M8/0273—Sealing or supporting means around electrodes, matrices or membranes with sealing or supporting means in the form of a frame
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M8/00—Fuel cells; Manufacture thereof
  • H01M8/02—Details
  • H01M8/0271—Sealing or supporting means around electrodes, matrices or membranes
  • H01M8/0286—Processes for forming seals
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M8/00—Fuel cells; Manufacture thereof
  • H01M8/10—Fuel cells with solid electrolytes
  • H01M2008/1095—Fuel cells with polymeric electrolytes
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
  • Y02E60/30—Hydrogen technology
  • Y02E60/50—Fuel cells

Definitions

• the invention relates to a method for producing a membrane-electrode assembly according to the preamble of claim 1.
• the invention also relates to a membrane-electrode assembly and a fuel cell having a membrane-electrode assembly according to the invention.
• a fuel cell can be used to convert chemical energy into electrical energy using a fuel, for example hydrogen, and an oxidizing agent, for example oxygen.
• the fuel cell has a membrane-electrode assembly (MEA) with a membrane that is coated on both sides with a catalytically active material to form electrodes.
• MEA membrane-electrode assembly
• the membrane which is coated on both sides, is usually laminated between two plastic films. This type of edge reinforcement is also called "gasket".
• the two plastic films have large windows so that the coated membrane remains free except for a narrow peripheral edge area.
• the free surfaces form active surfaces via which the proton exchange required for the electrochemical reaction takes place during operation of the fuel cell.
• the object of the present invention is therefore to improve the performance of a fuel cell with a laminated membrane-electrode arrangement. Furthermore, the membrane electrode assembly should be as simple and inexpensive to produce.
• the proposed method for producing a membrane electrode assembly for a fuel cell comprises the steps
• a membrane preferably a polymer membrane
• forming electrodes by coating the membrane on both sides with a catalytically active material
• the two plastic films are laid against the coated membrane on both sides in the edge area and are glued to one another outside the edge area.
• the active surfaces in the edge area of the membrane thus remain free of adhesive, specifically on both sides, ie both on the anode side and on the cathode side. Since the active areas are not covered by the adhesive, they are not deactivated either.
• the plastic foils lying on both sides of the membrane in the edge area alone do not lead to a deactivation of the active surfaces, since the reaction gases can also get under the plastic foils.
• the active surfaces thus extend under the plastic foils. This leads to an enlargement of the active areas and thus to an improvement in the performance of the membrane electrode assembly or the fuel cell produced from it. Since the plastic films are not glued over their entire surface in the proposed method, adhesive can also be saved. This reduces the costs of producing the membrane electrode assembly. Furthermore, membrane-electrode assemblies produced according to the proposed method have a lower weight. The coated membrane is held in the gasket by the rigidity of the plastic foils. In this way, edge reinforcement is also achieved without directly gluing the plastic films to the membrane.
• the adhesive used to bond the two plastic films is preferably only applied in regions to one or both plastic films. This means that the at least one plastic film remains free of adhesive in some areas. When applying the adhesive, the area that should remain free of adhesive can be covered with a shadow mask or the like.
• an area is preferably left free that is the same width as the bordered edge area of the membrane.
• other areas can be left free, provided that it is ensured that the two plastic films are secured against slipping.
• the adhesive also serves as a seal or gas barrier, it is preferably brought up to the edge area of the membrane.
• An end face of the membrane is preferably glued to the plastic films. This ensures that the active surfaces on both sides of the membrane remain free, but that the glued-in front surface does not allow gas exchange. It is harmless if a small part of the adhesive is pressed into the edge area when the plastic films are placed on the membrane and/or during a subsequent lamination process, so that the active surfaces in the edge area are not completely free of adhesive. This is within an allowable tolerance range and does not conflict with the claims.
• the plastic films are preferably provided with gaps before and/or after the adhesive bonding.
• First recesses can be used, for example, to form media channels. These are preferably arranged in end sections of the plastic films.
• the cut-outs can be special about punchings. These can be introduced into the plastic films before or after they are glued together. Further recesses or punched-out areas preferably serve to form window-like openings to expose the active surfaces of the coated membrane. These recesses or punched-out areas can only be produced before the plastic films are glued.
• a membrane-electrode arrangement for a fuel cell is also proposed.
• This comprises a membrane, preferably a polymer membrane, which is coated on both sides with a catalytically active material to form a first and a second electrode and is surrounded by a gasket in at least one edge area.
• the gasket is made of plastic foils that are in contact with the membrane on both sides and are bonded to one with the aid of an adhesive.
• the plastic films are free of adhesive at least in an area that overlaps with the edge area of the membrane.
• the active surface in the edge area of the membrane is therefore not covered by adhesive and consequently not deactivated either. This is because the plastic films lying against the membrane do not prevent the reaction gases from getting between the plastic films and the membrane.
• the membrane-electrode assembly or the fuel cell produced from it thus has improved performance. At the same time, the consumption of adhesive is reduced. Furthermore, the weight of the membrane-electrode arrangement and of the fuel cell produced from it is reduced.
• the proposed membrane-electrode arrangement can be produced in particular using the method according to the invention described above.
• the adhesive-free area of the plastic film has the same width as the bordered edge area of the membrane. This is to prevent adhesive from getting between the plastic films and the membrane. However, this cannot be completely ruled out and is within a tolerance range that does not contradict the invention.
• the adhesive preferably reaches up to an end face of the membrane, so that the end face of the membrane is glued to the plastic films. Gluing the end faces does not restrict the active surfaces of the coated membrane, so that this has no disadvantage in terms of the performance of the membrane-electrode assembly or the fuel cell. If the membrane is glued on the face side, the glue can also be used as a seal or gas barrier, which prevents gas transfer from one electrode side to the other electrode side.
• the plastic films preferably have recesses, preferably punched-out portions, for the formation of media channels.
• the recesses or punched-out areas overlap one another, so that media channels are formed in a stacked arrangement of fuel cells of the same type.
• the media channels serve to supply the fuel cell with the respective reaction gas.
• the plastic films preferably have further recesses or punched-out portions, which, however, have been introduced into the gasket before it is formed. These recesses or punched-out areas are large-area, window-like openings for exposing the active areas of the coated membrane.
• a circumferential edge reinforcement or a circumferential gasket can be formed that has a sufficiently high level of rigidity to hold the membrane. Direct bonding of the edge area of the membrane to the gasket is therefore not required.
• a fuel cell for a fuel cell stack which includes a membrane-electrode assembly according to the invention. Thanks to the membrane-electrode arrangement according to the invention, the fuel cell has better performance. In addition, it can be produced more cost-effectively since adhesive is saved. The material savings also reduce the weight of the fuel cell.
• FIG. 1 shows a perspective view of the individual elements of a membrane electrode assembly according to the invention before gluing
• Fig. 2 is a perspective view of the elements of FIG. 1 after bonding
• FIG. 3 shows a schematic cross section through the membrane electrode arrangement according to the invention of FIGS. 1 and 2.
• FIG. 1 shows a membrane 1 coated on both sides with a catalytically active material and two plastic films 6 , 7 which serve to form a gasket 4 .
• the two plastic films 6, 7 are placed on both sides of the coated membrane 1 in an edge area A and glued together outside of the edge area A.
• the two plastic films 6, 7 are of the same design, so that they cover one another after gluing. This also applies to cutouts 8, 9 provided in the plastic films 6, 7.
• the cutouts 8 are each formed in end sections 11, 12 of the plastic films 6, 7, so that media channels are formed on both sides of the membrane 1.
• the recesses 9 each serve to form a large window that leaves a large area of the coated membrane 1 free. This is the active area of the coated membrane 1.
• the recesses 9 are each bordered by a region B which remains free of adhesive s.
• the area B has a width that corresponds to the width of the edge area A (see FIG. 3).
• the plastic foils 6 , 7 are therefore essentially only glued to one another, but not to the edge area A of the membrane 1 .
• the structure of the membrane-electrode arrangement 10 is shown in FIG. From this it can be seen that the adhesive bonding of the plastic films 6 , 7 to one another also leads to an adhesive bonding of the plastic films 6 , 7 to the membrane 1 .
• the adhesion is limited to the area of an end face 13 of the membrane, so that the active areas of the membrane 1 are not restricted. This is because the edge region A remains free of adhesive 5.
• the gasket 4 is therefore only glued to the membrane 1 on the front side.
• the bonding on the face side forms a gas barrier which prevents gas from getting from one electrode side to the other electrode side of the membrane-electrode assembly 10 .

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• Life Sciences & Earth Sciences (AREA)
• Engineering & Computer Science (AREA)
• Manufacturing & Machinery (AREA)
• Sustainable Development (AREA)
• Sustainable Energy (AREA)
• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Electrochemistry (AREA)
• General Chemical & Material Sciences (AREA)
• Fuel Cell (AREA)

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Citations (3)

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• 2020
  • 2020-12-21 DE DE102020216363.4A patent/DE102020216363A1/de active Pending
• 2021
  • 2021-12-06 WO PCT/EP2021/084407 patent/WO2022135889A1/de active Application Filing
  • 2021-12-06 CN CN202190001003.0U patent/CN220526961U/zh active Active

Patent Citations (3)

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