Method for producing a MEA unit for an electrochemical cell, in particular a fuel cell, and device for producing a mea

Abstract

The invention relates to a method for producing a membrane electrode unit MEA (10) for an electrochemical cell, in particular a fuel cell, and to a device (100) for producing a membrane electrode unit (10) according to the method. According to the invention, it is believed that the MEA is laminated in the lamination unit (20) before the MEA is formed, for example by stamping in the stamping unit (40), and the MEA (10) is supported by the carrier ply (18) during the forming process.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a membrane electrode assembly (MEA) for electrochemical cells, particularly fuel cells, and an apparatus for manufacturing the MEA according to the method. Background Technology

[0002] The membrane electrode assembly (MEA), referred to below as MEA, is the core component of a polymer electrolyte membrane (PEM) fuel cell. Electrochemical reactions in the fuel cell or electrolysis device occur within the MEA. Therefore, the MEA is composed of various active materials with different functions; for example, a seven-layer structure of the MEA is known.

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

[0004] The composite structure consisting of a PEM membrane and an electrode is also known as a CCM (Catalyst-coated membrane). When the electrode is applied directly to the GDL, the composite structure consisting of a catalyst-coated GDL is also called a gas diffusion electrode (GDE). The GDL typically also has microporous sheets (MPL) on the catalyst side.

[0005] Electrodes typically include a catalyst used in conjunction with a so-called ionomer. The anodic hydrogen oxidation reaction and the cathodic oxygen reduction reaction occur at the catalyst surface. These reactions generate a usable electric current from the chemical energy of the fuel. The ionomer performs the electrolyte conduction function, while the catalyst support or the catalyst itself performs the electrical conduction function.

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

[0007] The function of the GDL and the MPL applied to it is to remove the reactants (hydrogen and oxygen from the air) of the electrochemical reaction and the water produced in the reaction from the electrode and also supply them to the electrode.

[0008] For the MEA to operate, the two electrodes must also be hermetically separated at their interfaces with the surroundings; this is ensured by so-called gaskets (sometimes also internal seals). Gaskets separate the dielectrics of the anode and cathode at the interface of the active materials (electrode, membrane, GDL / MPL).

[0009] EP3496194B1 describes a so-called planar-cut MEA, in which a central proton exchange membrane and an electrode sandwiched around the membrane are flush-sealed together, the electrode comprising a gas diffusion layer. Clean separation edges can be ensured when molding a single MEA composed of a 7-layer planar MEA composite material; unclean cutting of individual fibers of the GDL should be avoided, as these fibers may conductively bridge the proton exchange membrane. This will adversely affect the functionality of the MEA and therefore the functionality of the electrochemical cell housing the MEA. Summary of the Invention

[0010] Purpose

[0011] The object of this invention is to disclose a method for manufacturing membrane electrode units (MEAs) for electrochemical cells and to provide an apparatus for manufacturing membrane electrode units that enables the clean separation of individual MEAs made of a 7-layer sheet MEA composite material.

[0012] Solution

[0013] This objective is achieved by a method for manufacturing a membrane electrode assembly (MEA) as described and claimed below, and by an apparatus for manufacturing a membrane electrode assembly as described and claimed below.

[0014] According to the invention, it is considered advantageous to laminate the MEA prior to molding (e.g., by stamping the MEA) and to support the MEA with carrier sheets during the molding process.

[0015] The method according to the invention is used to manufacture membrane electrode units (MEAs) for electrochemical cells, especially fuel cells, and includes the following steps:

[0016] a) Provided as sheet materials respectively

[0017] The first layer sheet includes a gas-permeable layer sheet (GDL) and a microporous layer sheet (MPL);

[0018] The second layer, which serves as a catalyst-coated membrane layer, includes a proton exchange membrane (PEM) with catalyst layers (CL) applied to both sides of the PEM; and

[0019] The third layer comprises a gas-permeable layer (GDL) and a microporous layer (MPL).

[0020] b) The three aforementioned layers are combined together, such that these layers are sandwiched on top of each other to form a composite material to form a 7-layer membrane electrode unit (MEA).

[0021] c) Laminated 7-layer film electrode unit, i.e., a guided 7-layer film electrode unit passes through at least one calender roll pair, where the 7-layer film electrode units are joined together by temperature and pressure input. The individual layers of the 7-layer film electrode unit can therefore be further processed as a single component.

[0022] d) Provide a spreadable carrier sheet, which can be implemented in the form of a carrier film.

[0023] e) A carrier sheet is supplied to the 7-layer membrane electrode unit, such that the 7-layer membrane electrode unit is placed on the carrier sheet. This carrier sheet serves to reinforce and support the 7-layer membrane electrode unit, and to assist in cutting to completely sever the MEA and thus to cut straight edges without fibers. Both are then conveyed together to a subsequent forming unit, such as a stamping station.

[0024] f) To generate a single arc by separating the specified contour (Sollkontur). The 7-layer membrane electrode unit (MEA) is formed using a method that separates individual arc-shaped MEA units during the forming process. This individual arc-shaped MEA unit is referred to as the MEA nutzen, while the remaining sheet material is referred to as MEA scrap. If forming is performed by stamping, the MEA scrap is stamping waste or stamping residue. During forming, the carrier layers are not completely cut off, and are often weakened in their cross-section. By calendering the MEA before forming, and by incorporating carrier layers during the forming process, it is advantageously ensured that the 7-layer MEA unit is completely and cleanly cut along the predetermined separation profile. Furthermore, the 7-layer MEA unit is protected from potential contamination by the material beneath it.

[0025] An additional step is included in a favorable further improvement to this method:

[0026] g) Remove the waste material, leaving a single, arc-shaped 7-layer membrane electrode unit. In other words: remove the MEA waste and retain the useful MEA.

[0027] An advantageous further improvement to this method includes an additional step: h) removing the carrier layer, specifically by delaminating the carrier layer from the molded MEA. The carrier layer is used to assist in the molding process and can therefore be removed again after molding is complete.

[0028] The two steps described above—removing waste and removing the carrier layer—can also be performed simultaneously if necessary.

[0029] In a further advantageous improvement of the method, the resulting 7-layer membrane electrode unit has the following structure: a gas-permeable layer (GDL), a microporous layer (MPL), a catalyst layer (CL), a proton exchange membrane (PEM), a catalyst layer (CL), a microporous layer (MPL), and a gas-permeable layer (GDL).

[0030] In a further advantageous improvement to this method, lamination is performed using at least one heated pair of rollers. The roller pairs can be configured with the following material pairings: steel-steel, rubber-steel, or rubber-rubber. Lamination is particularly well performed under the following conditions, which have proven suitable and ensure particularly good handling of the 7-layer membrane electrode unit: temperatures ranging from 100°C to 200°C and pressures ranging from 0.5 MPa to 5 MPa.

[0031] In a further advantageous improvement to the method, the carrier layer is a carrier film made of plastic material.

[0032] In a further advantageous improvement to this method, forming is performed by stamping, particularly by continuous rotary stamping or quasi-continuous platform stamping.

[0033] Here, the stamping pressure prevents the carrier layer from being completely cut. The carrier layer thus forms a stamping base for the 7-layer membrane electrode unit, which is cut across its entire cross-section.

[0034] The present invention also relates to a method for manufacturing a fuel cell, wherein a membrane electrode unit is manufactured according to the above method, and then a sealing structure, a so-called gasket, is applied to one side of the membrane electrode unit, and then bipolar plates are applied to both sides respectively.

[0035] The present invention also relates to an apparatus for manufacturing a membrane electrode unit as described above, the apparatus having, and arranged sequentially along the conveying direction and the material flow direction:

[0036] a) One supply unit for each type of material, which is used to supply each type of material as a sheet material.

[0037] The first layer comprises a gas-permeable layer (GDL) and a microporous layer (MPL).

[0038] The second layer sheet includes a film sheet coated with a catalyst, and

[0039] The third layer comprises a gas-permeable layer (GDL) and a microporous layer (MPL).

[0040] b) A lamination unit for combining the three layers together to form a 7-layer film electrode unit.

[0041] d) A unit for providing sheet-type carrier layers.

[0042] e) A supply unit for supplying carrier sheets to the 7-layer membrane electrode unit. The carrier sheets reinforce and support the 7-layer membrane electrode unit, and both are continued to be conveyed together to the subsequent stamping unit, and finally...

[0043] f) A stamping unit used to form a 7-layer membrane electrode unit by separating a specified contour.

[0044] In a further improvement to the equipment, a processing unit for winding 7 layers of MEA waste material is also provided: g) a processing unit for winding 7 layers of MEA waste material.

[0045] In a further improvement of the device, an additional processing unit is provided: h) for delaminating and winding the carrier layer.

[0046] The present invention described herein and its advantageous further improvements described herein may also be combined with each other to constitute advantageous further improvements of the present invention, provided that they are technically reasonable.

[0047] Other advantages of the invention, as well as advantageous designs in terms of construction and function, are described with reference to the dependent claims and the accompanying drawings. Detailed Implementation

[0048] Example

[0049] The invention is intended to be explained in more detail with the aid of the accompanying drawings. Corresponding elements and components are given the same reference numerals in the drawings. To make the drawings clearer, actual scale is omitted. Attached Figure Description

[0050] As shown in the diagram:

[0051] Figure 1 The equipment used to manufacture MEAs is shown.

[0052] Figure 2 The structure of a 7-layer MEA is shown.

[0053] Figure 1An apparatus 100 for manufacturing a membrane electrode assembly (MEA) 10 is shown. A first sheet 15, comprising a gas permeable layer (GDL) 14 and a microporous layer (MPL) 13, is supplied as a planar material by a supply unit 25. A second planar sheet 16, comprising a membrane sheet 11 coated with a catalyst 12 (here in a horizontal transport plane), is supplied by another supply unit 26. A third sheet 15, again comprising a gas permeable layer (GDL) 14 and a microporous layer (MPL) 13, is supplied by another supply unit 25, such that the second sheet is sandwiched between the first and third sheets. These three sheets 15, 16, and 15 together constitute the MEA 10, which is then bonded together in a lamination unit 20 to form a planar 7-layer membrane electrode assembly as a composite material consisting of interconnected layers.

[0054] As the 7-layer membrane electrode unit 10 is guided through the laminating rollers 20, it is rolled and compressed. Thus, the individual layers of the 7-layer membrane electrode unit 10 are laminated and connected to each other particularly well again before further processing, especially before forming. A carrier sheet 18 is then provided and supplied to the 7-layer membrane electrode unit 10 by means of a providing unit 28a, such that the MEA 10 is supported on one side by the carrier sheet 18. Both are then further conveyed along the conveying direction T to the next post-processing station, to a stamping unit 40 configured for continuous operation with a rotary die. The stamping unit is used to form the 7-layer membrane electrode unit 10 by separating a specified contour. Thus, during the forming of the 7-layer membrane electrode unit 10, individual arc-shaped 7-layer membrane electrode units 10 are separated, which may also be referred to as MEA usable material, while the remaining slab material may be referred to as MEA scrap 19 or stamping scrap or stamping residue. During molding, the carrier layer 18 is not completely cut off, and in most cases it is weakened in its cross-section. This ensures that the 7-layer membrane electrode unit 10 is completely cut off along the set separation profile.

[0055] Next, the equipment 100 includes a processing unit 29 for winding the 7-layer MEA waste web material 19 and a processing unit 28b for delaminating and winding the carrier layer 18. The processing of the MEA waste web material 19 and the delamination of the carrier layer 18 can be performed simultaneously as shown here. However, it is also conceivable that these post-processing stations are arranged sequentially along the conveying direction. The remaining single arc-shaped 7-layer membrane electrode unit 10 can be continued to be conveyed by means of a conveying device 50 (e.g., a vacuum belt) and thus supplied to further post-processing, such as setting up pads and bipolar plates, and then supplied, for example, to a device for stacking MEA 10 or alternatively, temporarily stored.

[0056] Figure 2The structure of a 7-layer membrane electrode assembly (MEA) 10 is shown, as it can be manufactured on the aforementioned device 100. Only a fragment showing a cross-sectional view of the MEA 10 is shown. 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 are arranged sequentially and placed on top of each other, resulting in a structure symmetrical to the proton exchange membrane (PEM) 11. The gas permeable layer (GDL) 14 and the microporous layer (MPL) 13 together form a first layer 15, the proton exchange membrane (PEM) 11 forms a second layer 16, the catalyst layer (CL) 12 is applied to both sides of the proton exchange membrane, and the third layer 15 is again formed by the gas permeable layer (GDL) 14 and the microporous layer (MPL) 13. As described above, these three layers are laminated together to form a composite material.

[0057] Only a brief illustration shows the location of the temporary auxiliary MEA 10, i.e., the carrier layer 18 during the stamping process for forming a single arc MEA 10.

[0058] List of reference numerals

[0059] 10 7-layer MEA

[0060] 11. Proton exchange membrane (PEM)

[0061] 12. Catalyst Layers (CL)

[0062] 13. Microporous Laminates (MPLs)

[0063] 14. Gas-permeable layer (GDL)

[0064] 15. Sheet material composed of GDL and MPL

[0065] 16. Sheet material composed of laminated CL, PEM and CL

[0066] 18 carrier layers

[0067] 19 7-layer MEA waste material sheet

[0068] 20 Calendering unit with calender roll pairs twenty one

[0070] 25. Supply unit for providing gas-permeable sheets (GDL) and microporous sheets (MPL)

[0071] 28a A providing unit for providing carrier layers

[0072] 28b Processing unit for winding carrier sheets

[0073] 29. Disposal unit for winding 7-layer MEA waste fabric.

[0074] 40 stamping units

[0075] 50 Conveying device

[0076] 100 Equipment for manufacturing membrane electrode units

Claims

1. A method for manufacturing a membrane electrode assembly (MEA) (10) for use in electrochemical cells, particularly fuel cells, comprising the following steps: a) Provided as sheet materials respectively The first layer (15) includes a breathable layer (GDL) (14) and a microporous layer (MPL) (13); The second layer (16), which is a catalyst-coated membrane layer comprising a proton exchange membrane (PEM) (11), on both sides of which catalyst layers (CL) (12) are applied; and The third layer (15) comprises a breathable layer (GDL) (14) and a microporous layer (MPL) (13). b) The three layers (15, 16, 15) are combined together to form a 7-layer film electrode unit (10) of a wide area. c) Laminating the aforementioned 7-layer membrane electrode unit. d) Provide a sheet-like carrier layer (18), e) The carrier sheet (18) is supplied to the 7-layer membrane electrode unit (10) so that the 7-layer membrane electrode unit (10) is placed on the carrier sheet (18). f) The 7-layer membrane electrode unit (10) sheets are formed by separating a specified contour to produce a single arc-shaped 7-layer membrane electrode unit (10).

2. The method according to claim 1, wherein the method has an additional step: g) removing the waste (19) such that a single arc-shaped 7-layer membrane electrode unit (10) is left.

3. The method according to any one of the preceding claims, wherein the method comprises the additional step of: h) removing the carrier sheet (18), in particular by delaminating the carrier sheet (18).

4. The method according to any one of the preceding claims, characterized in that, The 7-layer membrane electrode unit formed in step b) has the following structure: 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).

5. The method according to any one of the preceding claims, characterized in that, The carrier layer (18) is a carrier film made of plastic material.

6. The method according to any one of the preceding claims, wherein in step f), forming is performed by stamping, in particular by continuous rotary stamping or quasi-continuous platform stamping.

7. A method for manufacturing a fuel cell, wherein a membrane electrode unit (10) is manufactured according to the method of any one of the preceding claims, a sealing structure is then applied to one side of the membrane electrode unit, and bipolar plates are then applied to both sides respectively.

8. An apparatus (100) for manufacturing a membrane electrode unit (10) according to the method of claim 1, the apparatus comprising: a) One supply unit (21, 25) for each of the following purposes: supplying sheet material. The first layer (15) comprises a gas-permeable layer (GDL) (14) and a microporous layer (MPL) (13). The second layer (16), which serves as a film layer (11) coated with catalyst (12), and The third layer (15) comprises a breathable layer (GDL) (14) and a microporous layer (MPL) (13). b) A lamination unit (20) for combining the three layers together to form a 7-layer film electrode unit. d) A supply unit (28a) for providing the sheet material (18) of the carrier layer, e) A supply unit for supplying the carrier sheet (18) to the 7-layer membrane electrode unit (10) of the web surface. f) A stamping unit (40) for forming the 7-layer film electrode unit (10) by separating a specified contour.

9. The apparatus for manufacturing a membrane electrode unit according to claim 8, wherein the apparatus comprises: g) a treatment unit (29) for winding 7 layers of MEA waste web material (19).

10. The apparatus for manufacturing a membrane electrode unit according to claim 8 or 9, wherein the apparatus comprises: h) a treatment unit (28b) for delaminating and winding the carrier sheet (18).

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