DE102017010160A1 - Method for producing a framed membrane electrode assembly for a fuel cell - Google Patents

Abstract

The invention relates to a method for producing a framed membrane electrode assembly (1) for a fuel cell. According to the invention, at least one coating side (B) of a membrane (4) coated over its entire surface or at least substantially over its entire area with catalyst layers (5) is a catalyst layer material (M) provided frame connection region (V) of the membrane (4) and the catalyst-coated membrane (3) in this frame connection region (V) connected to a frame (2).

Description

The invention relates to a method for producing a framed membrane electrode assembly for a fuel cell according to the features of the preamble of claim 1.

From the prior art, as in the EP 1 037 295 B2 described a method for applying electrode layers on a band-shaped polymer electrolyte membrane for fuel cells. In the process, continuous, simultaneous or sequential printing of front and back surfaces of a belt-shaped polymer electrolyte membrane is performed with electrode layers in a desired pattern using an electrocatalyst-containing ink and drying the electrode layers at elevated temperature immediately after each printing operation. The printing takes place in compliance with a positionally accurate arrangement of the patterns of the electrode layers of front and back to each other.

The invention is based on the object to provide a comparison with the prior art improved method for producing a framed membrane electrode assembly for a fuel cell.

The object is achieved by a method for producing a framed membrane electrode assembly for a fuel cell having the features of claim 1.

Advantageous embodiments of the invention are the subject of the dependent claims.

In a method according to the invention for producing a framed membrane electrode arrangement for a fuel cell, in particular for a PEM fuel cell (also referred to as polymer electrolyte membrane fuel cell or proton exchange membrane fuel cell), in particular for a fuel cell of a vehicle, from at least one coating side of a full surface or at least substantially membrane over the entire surface coated with catalyst layers, also referred to as membrane-catalyst film, a catalyst layer material in a designated frame connection area of the membrane removed, in particular removed, and the catalyst-coated membrane is connected in this frame connection area with a formed example of plastic frame by the Frame is connected to the now uncoated in this frame connecting region membrane, thereby advantageously formed the framed membrane electrode assembly is or at least a precursor for further processing to the framed membrane electrode assembly. In the latter case, at least the intermediate product for the framed membrane electrode assembly is produced by the method according to the invention.

It may also be provided that the compound is produced with a partially removed region (residues of catalyst material on the surface).

The catalyst-coated membrane is, for example, a polymer and / or plastic film which is coated on at least one side, advantageously on both sides, with catalyst layer material.

It can also be provided that the catalyst layer material is removed in an intended frame connection region from both sides of the membrane, in particular if it is intended to connect the frame with both sides of the membrane, for example, in each case a frame member each having a coating side, said frame elements for example Frame are joined together.

The solution according to the invention makes it possible to use a catalyst-coated membrane in which the catalyst layers have been applied over a large area, in particular over the entire area or at least substantially over the entire area, and for example continuously. Separation into individual catalyst-coated membranes can take place before or after connection to the respective frame.

By means of the local or large-area removal according to the invention, in particular removal, of the catalyst layer material in the intended frame connection region, a surface is achieved which is suitable for a permanent bond between membrane and frame. In particular, different joining possibilities can be used for the production of this composite.

It may also be provided a structure with a direct connection to the surface of the bipolar plate.

This is the problem with another production variant of the framed membrane electrode assembly which is disadvantageous to the solution according to the invention, in which the removal of the catalyst layer material in the connection region is not carried out, but the frame is glued directly onto the catalyst layer by applying an adhesive between surfaces of the catalyst-coated membrane and of the frame and thus on the catalyst layer is arranged. In this disadvantageous variant takes the Catalyst layer on the membrane during operation of the fuel cell water and upon subsequent freezing, the water and / or ice formed in the catalyst layer expands and breaks up the catalyst layer in it. Since this catalyst layer is also present in the frame connection area in this disadvantageous variant, leaks between the catalyst-coated membrane and the frame thereby arise, as a result of which gases of the fuel cell, for example hydrogen and air, can mix.

The inventive method provides the solution to remedy or at least improve the leaks occurring here, because by the inventive solution, the described problems of the disadvantageous variant are avoided or at least reduced. By the solution according to the invention an increased tensile and peel load of the connection between, for example, formed as a membrane catalyst film catalyst-coated membrane and the example formed of plastic frame before and after repeated freeze-start procedures is achieved. Furthermore, increased safety of the framed membrane electrode assembly against leaks, particularly in repeated freeze-start procedures, is achieved, thereby achieving longer life of the fuel cell and / or fuel cell stack from a plurality of such fuel cells.

The method according to the invention therefore makes it possible to optimize the surface for a joint connection that is more robust to leaks in the operation of the fuel cell.

An embodiment of the method provides that the catalyst layer material is removed by means of a laser. The use of the laser and thus the removal of the catalyst layer material in the intended frame connection region, locally or over a large area, by laser irradiation, enables this removal of the catalyst layer material in a particularly simple, fast and efficient manner. In particular, this also high accuracy in the removal of the catalyst layer material can be achieved, so as to ensure that the catalyst layer material is removed only in the intended area, and is completely removed in this area provided. Furthermore, this pre-processing of the membrane in the frame connection region by means of the laser enables a multiplicity of joining methods for connecting the frame to the membrane.

The frame connection region, in which the catalyst layer material is removed, may, for example, be circumferential around the membrane at the edge or be provided only in regions at the edge. For example, it may extend to a membrane edge and / or towards a center of the coating side a predetermined width, d. H. Expansion, have, d. H. it starts, for example, from the edge of the membrane and extends over the predetermined width in the direction of the center of the coating side. The removal of the catalyst layer material can be carried out in the entire intended frame connection area, d. H. in this frame connection area over the entire area or at least substantially over the entire area, or only in a subarea or several subregions of the frame connection area, then for example over a large area or only locally. For example, the catalyst layer material is removed in response to an intended joining process for bonding the frame to the membrane.

For example, the catalyst-coated membrane in the framing area is adhesively bonded and / or by a thermal joining process, i. H. Connection method connected to the frame by connecting the frame to the uncoated membrane in the frame connection area. For example, hot caulking and / or welding, in particular heating element welding, high-frequency welding, laser transmission welding, friction welding, in particular friction stir welding, ultrasonic welding, vibration welding and / or hot gas welding, injection-molding of the component by injection molding and / or transfer molding can be used in particular as the thermal joining method. The use of these and possible further joining methods is made possible by the removal of the catalyst layer material according to the invention, since thereby the membrane uncoated in the frame connection region is connected directly to the frame and thus the frame is not connected directly to the catalyst layer.

In one embodiment of the method, before the removal of the catalyst layer material, the catalyst-coated membrane is produced by applying the catalyst layer material on both sides of the membrane over the entire surface or at least substantially over the entire surface to form the catalyst layers. Ie. In this embodiment, the method also comprises the preparation of the catalyst-coated membrane, which takes place for example in the manner described above, in particular by a continuous coating of the membrane with the catalyst layer material.

For this purpose, for example, a membrane roll material is continuously coated on both sides simultaneously or first on one side of the coating and then on the other side of the coating with the catalyst layer material. Then you can For example, the separation into individual catalyst-coated membranes, which are then further processed in the manner described above for framed membrane electrode assembly, or it can be done first removing the catalyst layer material from the respective frame connection area and then singulating or singulation takes place only after the connection with the respective Frame.

Embodiments of the invention are explained in more detail below with reference to drawings.

• 1 schematisch einen Rahmen für eine gerahmte Membranelektrodenanordnung einer Brennstoffzelle in einer Draufsicht,
• 2 schematisch eine katalysatorbeschichtete Membran für eine gerahmte Membranelektrodenanordnung einer Brennstoffzelle in einer Draufsicht,
• 3 schematisch eine Ausführungsform einer gerahmten Membranelektrodenanordnung für eine Brennstoffzelle in einer Draufsicht,
• 4 schematisch eine Querschnittdarstellung der katalysatorbeschichteten Membran im Bereich der Schnittebene V-V in 3,
• 5 schematisch eine Querschnittdarstellung der gerahmten Membranelektrodenanordnung gemäß der Schnittebene V-V in 3,
• 6 schematisch eine Querschnittdarstellung der gerahmten Membranelektrodenanordnung gemäß der Schnittebene V-V in 3 nach wiederholten Gefrierstartprozeduren einer die gerahmte Membranelektrodenanordnung umfassenden Brennstoffzelle,
• 7 schematisch ein Bearbeitungsschritt in einem Verfahren zur Herstellung einer gegenüber 3 verbesserten Ausführungsform einer gerahmten Membranelektrodenanordnung für eine Brennstoffzelle, und
• 8 schematisch eine Querschnittdarstellung der mittels des Verfahrens hergestellten verbesserten Ausführungsform der gerahmten Membranelektrodenanordnung für eine Brennstoffzelle.

Showing:

• 1 schematically a frame for a framed membrane electrode assembly of a fuel cell in a plan view,
• 2 schematically a catalyst-coated membrane for a framed membrane electrode assembly of a fuel cell in a plan view,
• 3 1 schematically shows an embodiment of a framed membrane electrode arrangement for a fuel cell in a plan view,
• 4 schematically a cross-sectional view of the catalyst-coated membrane in the region of the sectional plane V - V in 3 .
• 5 schematically a cross-sectional view of the framed membrane electrode assembly according to the sectional plane V - V in 3 .
• 6 schematically a cross-sectional view of the framed membrane electrode assembly according to the sectional plane V - V in 3 after repeated freeze-start procedures of a fuel cell comprising the framed membrane electrode assembly,
• 7 schematically a processing step in a method for producing a opposite 3 improved embodiment of a framed membrane electrode assembly for a fuel cell, and
• 8th schematically a cross-sectional view of the produced by the method improved embodiment of the framed membrane electrode assembly for a fuel cell.

Corresponding parts are provided in all figures with the same reference numerals.

Based on 1 to 8th Hereinafter, a method of manufacturing a framed membrane electrode assembly will be described 1 for a fuel cell not shown here, in particular for a PEM fuel cell (also referred to as polymer electrolyte membrane fuel cell or proton exchange membrane fuel cell), in particular for a fuel cell of a vehicle. This framed membrane electrode assembly 1 includes an in 1 illustrated frame 2 , in particular plastic frames, and an in 2 represented catalyst coated membrane 3 , also referred to as membrane catalyst film. The catalyst-coated membrane 3 includes a membrane 4 , For example, a membrane film, and on both sides of the coating B this membrane 4 one catalyst layer each 5

The preparation of this catalyst-coated membrane 3 may also be a part of the process for producing the framed membrane electrode assembly 1 his. The catalyst-coated membrane 3 is made by applying to both sides of the coating B the uncoated membrane 4 by applying a catalyst layer material M the respective catalyst layer 5 is trained. This can be done on both sides of the coating B take place simultaneously or first on one side of the coating B and then on the other side of the coating B ,

Advantageously, this coating is carried out continuously, for example by using a membrane material as roll material, which is unrolled and coated continuously. As a result, a multiplicity of catalyst-coated membranes can be produced in a simple and rapid manner and thus at correspondingly lower production costs 3 getting produced. Separating the catalyst-coated membranes 3 by separating the roll material may then be, for example, after coating or after one or more processing operations described below for the preparation of the framed membrane electrode assembly 1 respectively.

In this preparation of the catalyst-coated membrane 3 or a plurality of them, for example in the manner described above, the coating is carried out with the catalyst layer material M over a large area, in particular over the whole area or at least substantially over the entire area, since a specific coating of individual membrane areas would be associated with a considerably higher outlay and resulting higher costs.

Based on 3 to 6 Now, first, an adverse embodiment of the preparation of the framed membrane electrode assembly 1 described, then the other hand, much more advantageous embodiment of the preparation of the framed membrane electrode assembly 1 and the resulting benefits based on the 7 and 8th to explain.

According to the in the 3 to 6 illustrated embodiment, the frame 2 with the catalyst coated membrane 3 connected by gluing, whereby the in 3 illustrated framed membrane electrode assembly 1 is trained. 4 shows a cross section of the catalyst-coated membrane 3 without the frame 2 , To connect to the frame 2 becomes an adhesive K between surfaces of the frame 2 and the catalyst coated membrane 3 arranged, ie directly on a surface of one of the catalyst layers 5 , This will be the frame 2 by means of the adhesive K directly with this catalyst layer 5 and only indirectly, namely via this catalyst layer 5 , with the membrane 4 connected, as in 5 based on a cross-sectional view according to the sectional plane V - V in 3 shown.

The disadvantage of this embodiment is, as in 6 shown in a cracking R in the catalyst layer 5 on which the adhesive K is arranged, due to repeated execution of freeze-start procedures of this framed membrane electrode assembly 1 comprehensive fuel cell and / or a fuel cell stack and / or a fuel cell system of a plurality of such fuel cells, in particular in vehicle applications. The catalyst layer 5 on the membrane 4 During operation of the fuel cell, water absorbs and upon subsequent freezing, the water and / or ice formed by freezing expands in the catalyst layer 5 and breaks the catalyst layer 5 in itself. Because this catalyst layer 5 also under a junction of frames 2 and catalyst coated membrane 3 ie in a frame connection area V , is present, there are leaks between the catalyst-coated membrane 3 and frame 2 , whereby gases of the fuel cell, for example hydrogen and air, can mix. This may, for example, lead to a loss of power or failure of the fuel cell.

At the in 7 and 8th the embodiment shown is connecting the frame 2 with the catalyst coated membrane 3 preceded by a removal step, ie it is first the catalyst layer material M in the intended framework connection area V from the membrane 4 removed, as in 7 and then the catalyst-coated membrane 3 in this framework connection area V in which the catalyst layer material M was removed with the frame 2 connected by the frame 2 with the in this connection area V uncoated membrane 4 is connected as in 8th shown.

The removal of the catalyst layer material M takes place in this example only on one of the two sides of the coating B the membrane 4 , In other examples, this may also be on both sides of the coating B in the respective frame connection area V especially if the frame 2 with both sides of the coating B the membrane 4 is to be connected, for example, by two frame elements, each with one of the coating pages B be connected and then connected to each other, for example.

The removal of the catalyst layer material M takes place in the frame connection area V for example, locally or over a large area. The catalyst layer material M can, for example, in the entire frame connection area V or only in one or more subregions of the frame connection area V from the membrane 4 be removed. The frame connection area V may be around the edge of the membrane 4 extend completely around or only over one or more partial perimeter areas. It extends for example from a membrane edge over a predetermined width in the direction of the center of the coating side B , The catalyst layer material can also be removed on both sides.

The removal of the catalyst layer material M takes place in the illustrated advantageous embodiment by means of laser L , d. h by means of irradiation by a laser L and thus by laser irradiation, shown schematically in FIG 7 as a laser beam. By means of the laser L becomes the catalyst layer material M from the membrane 4 ablated. The removal of the catalyst layer material M , in particular by the laser ablation, now offers a surface, ie that of the catalyst layer material M freed surface of the membrane 4 for a permanent bond with the frame 2 is suitable by means of different joining methods.

In addition, the fact that the catalyst layer material M was removed, a subsequent construction of the framed membrane electrode assembly 1 allows at which the frame 2 now directly with the membrane 4 connected, whereby the penetration of water into water-absorbing layers at the Verbundort of frames 2 and membrane 4 is avoided.

The removal of the catalyst layer material M In particular, by the laser pre-processing, it also allows all possible joining methods for this composite of frames 2 and membrane 4 apply. In the example shown here becomes the frame 2 with the membrane 4 directly glued, as in 8th shown. For this is the glue K between the frame 2 and the membrane 4 arranged and thereby on a surface of the frame 2 and the membrane 4 so the frame 2 by means of the adhesive K directly with the membrane 4 and thus with the entire catalyst-coated membrane 3 connected is.

For gluing frames 2 and membrane 4 For example, the adhesive K is applied to the frame 2 and / or on the frame connection area V the membrane 4 applied and then frame 2 and membrane 4 glued together. By removing the catalyst layer material M in the frame connection area V from the membrane 4 , in particular by means of laser L Furthermore, other joining methods are also possible, for example gluing and / or thermal joining methods such as hot caulking and / or welding.

The removal of the catalyst layer material M in the frame connection area V from the membrane 4 in particular by the laser ablation method, provides the solution to remedy or at least improve the above-described leaks. In addition, this results in an increased tensile and peel stress of the bond between the catalyst-coated membrane 3 and frame 2 increased safety and robustness of the framed membrane electrode assembly 1 achieved against leaks and thus a longer life of the fuel cell and / or the fuel cell stack of a plurality of such fuel cells.

Furthermore, by removing the catalyst layer material M in the frame connection area V , in particular by means of laser L , before connecting to the frame 2 the use of a large area, continuously applied catalyst layer 5 on the membrane 4 allowing, as described above, the preparation of the catalyst-coated membrane 3 is significantly simplified because no targeted order of the catalyst layer material M only on parts of the membrane 4 is required.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• EP 1037295 B2 [0002]

Claims (8)

Method for producing a framed membrane electrode assembly (1) for a fuel cell, characterized in that from at least one coating side (B) of a membrane (4) coated over its entire area or at least substantially over its entire area with catalyst layers (5), a catalyst layer material (M) is provided in an intended frame connection area (V) is removed from the membrane (4) and the catalyst-coated membrane (3) in this frame connection region (V) is connected to a frame (2). Method according to Claim 1 , characterized in that the catalyst layer material (M) by means of a laser (L) is removed. Method according to one of the preceding claims, characterized in that the catalyst layer material (M) in the edge around the membrane (4) circulating frame connection region (V) is removed. Method according to one of the preceding claims, characterized in that the frame connection region (V), in which the catalyst layer material (M) is removed, extends to a membrane edge. Method according to one of the preceding claims, characterized in that the frame connection region (V), in which the catalyst layer material (M) is removed, in the direction of a center of the coating side (B) has a predetermined width. Method according to one of the preceding claims, characterized in that the catalyst-coated membrane (3) in the frame connection region (V) by gluing and / or by a thermal joining method with the frame (2) is connected. Method according to one of the preceding claims, characterized in that the catalyst-coated membrane (3) in the frame connection region (V) by welding, by hot caulking, by Heizelementschweißen, by high frequency welding, by laser transmission welding, by friction welding, in particular friction stir welding, by ultrasonic welding, by vibration welding and / or by hot gas welding, by encapsulation of the component, in particular by injection molding and / or transfer molding with the frame (2) is connected. Method according to one of the preceding claims, characterized in that before the removal of the catalyst layer material (M), the catalyst-coated membrane (3) is prepared by the catalyst layer material (M) on both coating sides (B) of the membrane (5) for forming the catalyst layers (5). 4) over the entire surface or at least substantially over the entire surface is applied.

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