Method for manufacturing a membrane electrode assembly (MEA) for an electrochemical cell, in particular a fuel cell, and equipment for manufacturing the MEA

Abstract

The invention relates to a method for manufacturing a membrane electrode assembly (MEA) (10) for an electrochemical cell, in particular a fuel cell, and to a system (100) for manufacturing a membrane electrode assembly (10) according to this method. According to the invention, it was identified as advantageous to laminate the MEA in a lamination unit (20) before the MEA is assembled, e.g. by punching in a punching unit (40), and to support the MEA (10) during the assembly process by a carrier layer (18).

Description

[0001] The invention relates to a method for manufacturing a membrane electrode assembly (MEA) for an electrochemical cell, in particular a fuel cell, and to a system for manufacturing a membrane electrode assembly according to this method. State of the art

[0002] Membrane electrode assemblies (MEAs), hereinafter referred to as MEAs, are the core component in polymer electrolyte membrane (PEM) fuel cells. The electrochemical reactions of a fuel cell or electrolyzer take place within the MEA. Therefore, the MEA consists of various functional active materials; a 7-layer structure is one well-known example.

[0003] In the simplest case, the MEA comprises a proton exchange membrane (PEM) made of a polymeric, ion-conducting material enclosed in two electrodes (anode and cathode), each consisting of a carbon catalyst layer, on each side a microporous layer (MPL) and a porous, air-permeable gas diffusion layer (GDL).

[0004] The composite of the PEM membrane and the electrodes is also known as CCM (catalyst-coated membrane). When the electrodes are applied directly to the GDL, the resulting composite of catalyst-coated GDL is also called a gas diffusion electrode (GDE). The GDL is typically coated with a microporous layer (MPL) on the catalyst side.

[0005] The electrodes typically comprise catalysts combined with a so-called ionomer. The anodic hydrogen oxidation reaction and the cathodic oxygen reduction reaction take place on the catalyst surface. These reactions generate the usable electricity from the chemical energy of the fuels. The ionomer performs the electrolytic conduction function, while the catalyst support or the catalyst itself performs the electrical conduction.

[0006] The membrane separates the electrodes from each other. It prevents not only the flow of electrons but also the exchange of gases between the two electrodes. In addition to its separating function, the membrane also allows the diffusion of protons (product of the anodic hydrogen oxidation reaction) from the anode to the cathode. These protons react at the cathode to form water.

[0007] The GDL and the MPL applied to it have the function of supplying the reactants of the electrochemical partial reactions (hydrogen and atmospheric oxygen) as well as the water produced during the reactions to and from the electrodes.

[0008] To operate the MEA, the two electrodes must also be gas-tightly separated at the interface with the periphery; this is ensured by the so-called gasket (sometimes also called an internal seal). The gasket separates the media of the anode and cathode at the interface of the active materials (electrodes, membrane, GDL / MPL).

[0009] EP 3 496 194 B1 describes so-called flush-cut MEAs, in which the central proton exchange membrane and the surrounding electrodes, forming a sandwich, form a flush seal with the gas diffusion layers. When fabricating individual MEAs from a web-like, 7-layer MEA composite material, a clean cut edge must be ensured; it is essential to avoid incompletely cutting individual fibers of the gas diffusion membrane, as these could create an electrically conductive bridge across the proton exchange membrane. This would adversely affect the functionality of the MEA and, consequently, the electrochemical cell it houses. Task

[0010] The object of the present invention is to describe a method for manufacturing a membrane electrode assembly (MEA) for an electrochemical cell and to provide a system for manufacturing a membrane electrode assembly which enables the assembly of individual MEAs from a web-shaped 7-layer MEA composite material with a clean separation edge. Technical solution

[0011] This problem is solved by a method for manufacturing a membrane electrode assembly (MEA) as described and claimed below, and by a system for manufacturing a membrane electrode assembly as described and claimed below.

[0012] According to the invention, it was recognized as advantageous to laminate the MEA before assembly, e.g. by punching, and to support the MEA during the assembly process with a carrier layer.

[0013] The inventive method serves to manufacture a membrane electrode assembly (MEA) for an electrochemical cell, in particular a fuel cell, and comprises the following steps: a) Providing a 1. Layer comprising a gas-permeable layer (GDL) and a microporous layer (MPL), a 2. Layer comprising a proton exchange membrane (PEM) coated with catalysts, on which a catalyst layer (CL) is applied on both sides and a 3. Layer comprising a gas-permeable layer (GDL) and a microporous layer (MPL), each as a sheet-like material. b) Combining the three aforementioned layers in such a way that the layers, sandwiched together, form a web-shaped 7-layer membrane electrode assembly (MEA) as a composite material. c) Laminating the web-shaped 7-layer membrane electrode assembly, i.e., passing the web-shaped 7-layer membrane electrode assembly through at least one pair of calender rollers, whereby the 7-layer membrane electrode assembly is bonded together by the application of temperature and pressure. The different layers of the 7-layer membrane electrode assembly can then be processed as a single component. d) Providing a web-shaped support layer, which may be designed as a support film. e) Feeding the carrier layer to the web-shaped 7-layer membrane electrode assembly (MEA) in such a way that the MEA rests on the carrier layer. The carrier layer serves to reinforce and support the MEA, as well as to support the cutting process for a complete cut through the MEA and thus a straight, fiber-free cut edge. Both are then conveyed together to a subsequent processing unit, e.g., a punching station. f) Assembling the 7-layer membrane electrode assembly by cutting out the desired contour, such that individual arc-shaped 7-layer membrane electrode assemblies are created. When assembling from the web-shaped 7-layer membrane electrode assembly, individual arc-shaped 7-layer membrane electrode assemblies are cut out, which can also be referred to as MEA panels, whereas the remaining web material can be referred to as MEA waste. If the assembly is carried out by die-cutting, the MEA waste is die-cutting waste or die-cutting residue. During assembly, the substrate layer is not completely severed; at most, its cross-section is weakened.Calendering the MEA before assembly, combined with providing a support layer for the duration of the assembly process, advantageously ensures that the 7-layer membrane electrode assembly is completely and cleanly cut along the intended separation contour. Furthermore, the 7-layer membrane electrode assembly is protected from potential contamination by the underlying material.

[0014] A further step is planned as an advantageous further development of the procedure: g) Removal of the waste, leaving individual arc-shaped 7-layer membrane electrode assemblies. In other words: the MEA waste is removed, the MEA benefits remain.

[0015] A further step is planned as an advantageous further development of the procedure: h) Removal of the carrier layer, in particular by delaminating the carrier layer from the assembled MEA. The carrier layer serves to support the assembly process step and can therefore be removed again after assembly has been completed.

[0016] The two aforementioned steps, removing the waste and removing the support layer, can also be carried out simultaneously if necessary.

[0017] In an advantageous further development of the process, the formed web-shaped 7-layer membrane electrode unit has the following structure: Gas-permeable layer (GDL), microporous layer (MPL), catalyst layer (CL), proton exchange membrane (PEM), catalyst layer (CL), microporous layer (MPL), gas-permeable layer (GDL).

[0018] In a further advantageous development of the process, lamination is carried out with at least one heated roller pair. The following material pairings can be used for the roller pairs: Steel-steel, rubber-steel, rubber-rubber. Lamination is carried out particularly under the following conditions, which have proven to be advantageous and ensure particularly good treatment of the web-shaped 7-layer membrane electrode assembly: a pressure in the range of 0.5 MPa - 5 MPa at a temperature in the range of 100°C-200°C.

[0019] In an advantageous further development of the process, the carrier layer is a carrier film made of a plastic material.

[0020] In an advantageous further development of the process, the assembly is carried out by punching, in particular by continuous rotary punching or quasi-continuous flatbed punching.

[0021] The punching pressure is such that the carrier layer is not completely severed. This forms a punching surface for the 7-layer membrane electrode assembly, which is cut through its entire cross-section.

[0022] The invention also relates to a method for manufacturing a fuel cell, wherein a membrane electrode assembly is manufactured according to the method described above and then a sealing structure, a so-called gasket, is applied to one side of the membrane electrode assembly, and then a bipolar plate is applied to both sides.

[0023] The invention also relates to a system for the production of a membrane electrode assembly as described above, comprising and arranged one after the other in the direction of transport and material flow. a) one supply unit each for supply as web-shaped material of a 1. Layer comprising a gas-permeable layer (GDL) and a microporous layer (MPL), a 2nd layer as a membrane layer coated with catalysts and a 3. Layer comprising a gas-permeable layer (GDL) and a microporous layer (MPL) b) a lamination unit for joining the 3 layers in such a way that a web-shaped 7-layer membrane electrode unit is formed, d) a provisioning unit for providing a track-shaped support layer, e) a feeding unit for feeding the carrier layer to the web-shaped 7-layer membrane electrode assembly. The carrier layer serves to reinforce and support the 7-layer membrane electrode assembly, and both are transported together to a subsequent punching unit and finally f) a punching unit for preparing the 7-layer membrane electrode unit by cutting out the desired contour.

[0024] Further development of the plant is planned to include: g) a disposal unit for winding up the 7-layer MEA waste web.

[0025] Further development of the plant is planned to include: h) a disposal unit for delaminating and winding up the carrier layer.

[0026] The described invention and the described advantageous further developments of the invention also represent advantageous further developments of the invention when combined with each other - insofar as this is technically sensible.

[0027] Regarding further advantages and structurally and functionally advantageous embodiments of the invention, reference is made to the dependent claims and the description of exemplary embodiments with reference to the accompanying figures. Example of implementation

[0028] The invention will be explained in more detail with reference to the accompanying figures. Corresponding elements and components are identified by the same reference numerals in the figures. For the sake of clarity, the figures are not drawn to scale.

[0029] They show in schematic representation Fig. 1 a plant for the production of an MEA Fig. 2. the structure of a 7-layer MEA

[0030] Fig. Figure 1 shows a system 100 for the production of an MEA, a membrane electrode assembly 10. A first layer 15, comprising a gas-permeable layer (GDL) 14 and a microporous layer (MPL) 13, is supplied as a web-like material from a supply unit 25. A second web-like layer 16, comprising a membrane layer 11 coated with catalysts 12, is supplied from another supply unit 26 – here in the horizontal transport plane – and a third layer 15, again comprising a gas-permeable layer (GDL) 14 and a microporous layer (MPL) 13, is supplied from another supply unit 25, so that the second layer lies between the first and third layers and is sandwiched in place. These three layers 15, 16, 15 together form the MEA 10, which are brought together in a lamination unit 20 in such a way that a web-shaped 7-layer membrane electrode unit is formed as a composite material from interconnected layers.

[0031] As the web-shaped 7-layer membrane electrode assembly 10 passes through the laminating roller pair 20, it is rolled and subjected to pressure. The various layers of the 7-layer membrane electrode assembly 10 are thus laminated and bonded together particularly well before further processing, especially assembly. A web-shaped support layer 18 is then provided by a supply unit 28a and fed to the web-shaped 7-layer membrane electrode assembly 10, so that the MEA 10 is supported on one side by the support layer 18. Both are then transported in the transport direction T to the next processing station, a punching unit 40 designed as a continuously operating rotary die cutter. This unit serves to assemble the 7-layer membrane electrode assembly 10 by cutting out the desired contour.During the assembly process from the web-shaped 7-layer membrane electrode unit 10, individual arc-shaped 7-layer membrane electrode units 10 are cut out, which can also be referred to as MEA panels, whereas the remaining web material can be referred to as MEA waste 19 or as die-cutting waste or die-cutting residue. During assembly, the carrier layer 18 is not completely cut through, but at most experiences a weakening in its cross-section. This ensures that the 7-layer membrane electrode unit 10 is completely cut through along the intended cutting contour.

[0032] The system includes a disposal unit 29 for winding the 7-layer MEA waste web 19 and a disposal unit 28b for delaminating and winding the support layer 18. Disposing of the MEA waste web 19 and delaminating the support layer 18 can be performed simultaneously, as shown here. However, it would also be conceivable to arrange these processing stations sequentially in the direction of transport. The remaining individual arc-shaped 7-layer membrane electrode units 10 can be transported further by means of a transport device 50 (e.g., a vacuum belt) and thus supplied for further processing, e.g., fitted with gaskets and bipolar plates and then, for example, fed to a device for stacking the MEAs 10, or they can alternatively be temporarily stored.

[0033] Fig.Figure 2 shows the structure of a 7-layer membrane electrode assembly (MEA) 10, as it can be manufactured on the system 100 described above. Only a section is shown as a cross-sectional view through the MEA 10. The following layers are arranged sequentially and superimposed on one another: a gas-permeable layer (GDL) 14, a microporous layer (MPL) 13, a catalyst layer (CL) 12, a proton-exchange membrane (PEM) 11, a catalyst layer (CL) 12, a microporous layer (MPL) 13, and a gas-permeable layer (GDL) 14, resulting in a structure symmetrical with respect to the proton-exchange membrane (PEM) 11. A gas-permeable layer (GDL) 14 and a microporous layer (MPL) 13 together form a 1st layer 15, a proton exchange membrane (PEM) 11 on which a catalyst layer (CL) 12 is applied on both sides forms a 2nd layer 16 and a 3rd layer (15) is formed again by a gas-permeable layer (GDL) 14 and a microporous layer (MPL) 13.The three layers are laminated together to form a composite material as described above.

[0034] The position of the carrier layer 18, which temporarily supports the MEA 10, is only indicated, namely during the punching process for assembling the individual arc-shaped MEAs 10. Reference symbol list 10 7-layer MEA 11 Proton exchange membrane (PEM) 12 catalyst layer (CL) 13 microporous layer (MPL) 14 gas-permeable layer (GDL) 15 trains from GDL and MPL 16 lanes made of laminated CL, PEM and CL 18 Support position 19 7-layer MEA waste conveyor 20 Calendering unit with calender roller pair 21 25 Provisioning unit for providing a gas-permeable layer (GDL) and a microporous layer (MPL) 28a Provisioning unit for the provision of a support layer 28b Disposal unit for winding up the carrier layer 29 Disposal unit for winding up the 7-layer MEA waste web 40 punching units 50 transport equipment 100 Plant for the production of a membrane electrode assembly QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] EP 3 496 194 B1

[0009]

Claims

[1] Method for manufacturing a membrane electrode assembly (MEA) (10) for an electrochemical cell, in particular a fuel cell, comprising the following steps: a) Providing a 1. Layer (15) comprising a gas-permeable layer (GDL)(14) and a microporous layer (MPL)(13), a 2. Layer (16) comprising a catalyst-coated membrane layer, a proton exchange membrane (PEM) (11) on which a catalyst layer (CL)(12) is applied on both sides and a 3. Layer (15) comprising a gas-permeable layer (GDL)(14) and a microporous layer (MPL)(13), each as a web-shaped material b) Combining the three layers (15, 16, 15) such that a web-shaped 7-layer membrane electrode assembly (10) is formed c) Laminating the web-shaped 7-layer membrane electrode assembly d) Providing a track-shaped support layer (18) e) Feeding the carrier layer (18) to the web-shaped 7-layer membrane electrode assembly (10) such that the web-shaped 7-layer membrane electrode assembly (10) rests on the carrier layer (18), f) Assembling the 7-layer membrane electrode assembly (10) by cutting out the desired contour in such a way that individual arc-shaped 7-layer membrane electrode assemblies (10) are created [2] Method according to claim 1 with the further step g) Removing the waste (19) in such a way that individual arc-shaped 7-layer membrane electrode units (10) remain. [3] Method according to any of the preceding claims, with the further step of: h) Removal of the support layer (18), in particular by delaminating the support layer (18). [4] Method according to any of the preceding claims, characterized by , that the track-shaped 7-layer membrane electrode assembly formed in step b) has the following structure: Gas-permeable layer (GDL)(14), Microporous layer (MPL)(13), Catalyst layer (CL)(12), Proton exchange membrane (PEM)(11), Catalyst layer (CL)(12), Microporous layer (MPL)(13), Gas permeable layer (GDL)(14). [5] Method according to any of the preceding claims, characterized by , that the carrier layer (18) is a carrier film made of a plastic material. [6] Method according to one of the preceding claims, wherein in step f) the assembly is carried out by punching, in particular by continuous rotary punching or quasi-continuous flatbed punching. [7] Method for manufacturing a fuel cell, wherein a membrane electrode assembly (10) is manufactured according to the method of one of the preceding claims, then a sealing structure is applied to one side of the membrane electrode assembly and then a bipolar plate is applied to each side. [8] Apparatus (100) for manufacturing a membrane electrode assembly (10) according to the method of claim 1, comprising a) each a provisioning unit (21, 25) for provision as web-shaped material of a 1. Layer (15) comprising a gas-permeable layer (GDL) (14) and a microporous layer (MPL) (13), a 2. Layer(16) as a membrane layer (11) coated with catalysts (12) and a 3. Layer (15) comprising a gas-permeable layer (GDL)(14) and a microporous layer (MPL)(13) b) a lamination unit (20) for joining the 3 layers such that a web-shaped 7-layer membrane electrode unit is formed d) a provisioning unit (28a) for providing a track-shaped support layer (18) e) A feed of the carrier layer (18) to the web-shaped 7-layer membrane electrode assembly (10) f) a punching unit (40) for preparing the 7-layer membrane electrode unit (10) by cutting out the desired contour. [9] Apparatus for the production of a membrane electrode assembly according to claim 8 with g) a disposal unit (29) for winding up the 7-layer MEA waste web (19). [10] Apparatus for the production of a membrane electrode assembly according to claim 8 or 9 with h) a disposal unit (28b) for delaminating and winding up the carrier layer (18).

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