WO2012163383A1

WO2012163383A1 - Electrolyte membrane assembly for a fuel cell and method for the production thereof

Info

Publication number: WO2012163383A1
Application number: PCT/EP2011/006268
Authority: WO
Inventors: Dirk Lindenau; Matteo Scolari
Original assignee: Daimler Ag
Priority date: 2011-06-01
Filing date: 2011-12-13
Publication date: 2012-12-06
Also published as: DE102011106767B3

Abstract

The invention relates to a multi-layer electrolyte membrane assembly (1) for a fuel cell, comprising a reinforcing layer (2) having a perforated sub-region (2.1) and an unperforated edge region (2.2) surrounding the perforated region (2.1) at the edge of the perforated region. The perforated sub-region (2.1) is coated with an ion-conductive material such as to form a semipermeable membrane layer (3).

Description

Electrolyte membrane assembly for a fuel cell and method for its production

The invention relates to a multilayer electrolyte membrane arrangement with an amplifier layer. The invention further relates to a method for producing an electrolyte membrane arrangement for a fuel cell, in particular a

Polymer electrolyte fuel cell.

From the prior art, fuel cells are known which a solid

Polyelectrolyte membrane of, for example, a sulfonated tetrafluoroethylene polymer. The polyelectrolyte membrane separates an anode side of the fuel cell from a cathode side. Typically, hydrogen is catalytically oxidized to protons at the anode side by the emission of electrons. The protons diffuse through the polymer electrolyte membrane to the cathode where they react with oxygen to form water. Thus, in the reaction, chemical energy is converted into electrical energy which is used, one between anode and cathode

operated electrical consumers.

The prior art further includes fuel cells in which methanol, formic acid, methane, a coal gas, carbon or magnesium is used as fuel on the anode side. As the polymer electrolyte membrane diffusing ion, according to the type of fuel cell also hydroxide, oxonium, or radical dioxide ions can be used.

US 2005/0227132 A1 discloses a multilayer electrolyte membrane arrangement which has a porous amplifier layer with an aperture ratio between 50% and 90%. The amplifier layer is completely in one

Polymer electrolyte membrane introduced. In particular, the overlap

Amplifier layer and arranged thereon polymer electrolyte membrane completely. The polyelectrolyte membrane is coated on both sides with a catalyst layer, which is a Having carbon powder, which serves as a support material for a catalytic metal such as platinum.

The invention is based on the object, an improved over the prior art electrolyte membrane assembly and an improved method for

Specify preparation of the electrolyte membrane assembly.

The object is achieved by an electrolyte membrane assembly having the features of claim 1 and by a method for producing the electrolyte membrane assembly with the characterizing features of

Patent claim 6.

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

A multilayered electrolyte membrane assembly for a fuel cell has an amplifier layer with a perforated portion and a perforated portion

Partial area surrounding, imperforate edge area on. The perforated portion is coated with an ion-conductive material, so that a

semipermeable membrane layer is formed. The semipermeable membrane layer is particularly permeable only to molecules, ions or particles below a predeterminable size.

Typically, prior art polymer electrolyte membranes formed from the ion-conductive material are very thin (10-30 μιη) and mechanically sensitive. Therefore, such polymer electrolyte membrane can be laboriously glued or welded, which also with the risk of damaging the

Polymer electrolyte membrane is accompanied. The amplifier layer is preferably formed from a mechanically, thermally and / or chemically resistant material. The arrangement of the ionic conductive material on the support material of the amplifier layer increases the mechanical robustness and thus helps to avoid damage during production. In particular, so waste can be reduced during production. The protruding edge region of the amplifier layer allows a simplified handling of the electrolyte membrane assembly during manufacture, whereby contact with the sensitive region of the semipermeable membrane layer is avoided. Furthermore, the protruding edge region provides an enlarged joining surface, which in particular is quick and easy with other components the fuel cell can be glued and / or welded. Preferably, the amplifier layer is formed from a low cost material to reduce manufacturing costs.

Preferably, the ionic conductive material is an ionomer, such as a sulfonated tetrafluoroethylene polymer, such that the semipermeable membrane layer of the electrolyte membrane assembly is permeable, at least for protons. Alternatively, the ionically conductive material may have a permeability such that the semipermeable membrane layer formed by the ionically conductive material is permeable to at least one of a hydroxide ion, an oxonium ion, and a free radical dioxide ion.

Preferably, the amplifier layer is of a low cost

Plastic material, such as in particular a polymer formed, which has an increased mechanical, thermal and / or chemical robustness compared to the ion-conductive material. This advantageously reduces material costs and production costs.

According to a preferred embodiment of the invention, at least one reinforcing frame element is materially connected to the edge region of the amplifier layer such that the frame element surrounds the edge of the semipermeable membrane layer. The cohesive connection between the frame region and the edge region takes place in particular by means of a bond or a weld. In this case, the edge region projecting beyond the semipermeable membrane layer ensures a flat connection surface, so that in particular the connection between frame element and edge region can be made fluid-tight.

Preferably, the semipermeable membrane layer is coated with a catalyst layer. In particular, the semipermeable membrane layer with the

Catalyst layer to be printed. The catalyst layer may for example consist of a carbon support and a catalytically active material such as platinum. The catalyst layer serves at least as part of an electrode of the

Brennstofffzelle. The semipermeable membrane layer is in particular with a

Catalyst layer coated to form an anode or a cathode. Furthermore, one or more gas diffusion layers can be arranged on the catalyst layers, which are correspondingly permeable to gases such as hydrogen or oxygen. In a method of manufacturing the electrolyte membrane assembly is

According to the invention, in a first method step, at least one subregion of an amplifier layer is perforated in such a way that an imperforate edge region surrounding the subregion is formed on the edge. In a second method step, the perforated portion is coated with an ion-conductive material to form a semipermeable membrane layer of the electrolyte membrane assembly. The electrolyte membrane arrangement thus formed has an increased mechanical, thermal and / or chemical robustness. The manufacturing method allows an economical production of the electrolyte membrane arrangement, as a direct bonding or welding of the mechanically sensitive ion-conductive material of the semipermeable membrane layer is avoided. This reduces the risk of

Damage and thus rejects during production. Furthermore, a low-cost plastic material can be used for the amplifier layer, so that material costs are saved. In particular, an ionomer can be used as the ion-conductive material.

Preferably, in a subsequent third process step, at least the semipermeable membrane layer is printed or coated with a catalyst layer. The catalyst layer comprises at least one catalytically active material such as platinum or a platinum alloy and forms an electrode of the fuel cell. Preferably, the semipermeable membrane layer is coated on both opposite sides to form the anode and the cathode of the fuel cell with the catalyst layer. As the catalytically active platinum alloy, for example, platinum-ruthenium, platinum-nickel or platinum-cobalt alloys are suitable.

In a preferred exemplary embodiment, in a fourth method step, at least one reinforcing frame element with the edge region of the

Amplifier layer bonded cohesively. The frame element completely surrounds the semipermeable region of the amplifier layer at the edge, so that the semipermeable membrane layer and / or the catalyst layer arranged thereon are completely covered by an inner cutout surface of the frame element.

Preferably, the edge region of the amplifier layer on both sides with two

glued or welded to the opposite frame members to the mechanical Robustness of the electrolyte membrane assembly to increase advantageous.

According to a preferred embodiment, the amplifier layer is made

Roll material made of a plastic film. For the production of

Electrolyte membrane assembly takes place either before the first process step or after the third process step, a separating step in which the roll goods are cut. Process technology is particularly advantageous if the

Perforation of the portion, the application of the ion-conductive material and the subsequent coating with the catalyst layer already done on the roll of the plastic film. The perforated and coated plastic film will

then cut and in particular welded or glued to the frame member to form the electrolyte membrane assembly. The processing of

Rolled goods enable a continuous production process, which can be integrated particularly advantageously into a correspondingly automated production line.

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

FIGS. 1A to 1 D schematically illustrate method steps for producing a

Electrolyte membrane assembly.

Fig. 2 shows a roll of a plastic film having portions which are perforated to produce the electrolyte membrane assembly and then coated with a catalyst layer.

Fig. 3 shows the electrolyte membrane assembly in a sectional view.

4 shows a sectional view of the electrolyte membrane arrangement with enclosing frame elements.

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

FIGS. 1A to 1 D schematically illustrate individual method steps for producing an electrolyte membrane arrangement 1. FIG. 1A shows an amplifier layer 2 for a multilayer

Electrolytic Membrane Arrangement 1. An inner portion 2.1 of the amplifier layer 2 is perforated in a first method step by means of suitable punching or perforating tools. The amplifier layer 2 has a circumferential edge region 2.2, which is imperforate and the peripheral portion of the perforated portion 2.1 rotates.

The amplifier layer 2 is produced, for example, from individual sheets of a plastic film K or from rolls of the plastic film K, as shown in FIG. In the production of rolled goods, individual sections A1 to An of the plastic film K are preferably first perforated in such a way that each inner partial area 2.1 of the section A1 to An is surrounded correspondingly by the imperforate edge area 2.2.

The plastic film K consists of a cost-effective material which has sufficient mechanical, thermal and chemical robustness. Suitable plastic films may for example consist of a polymer, polyethylene or a polypropylene.

In a second method step, as shown in FIG. 1B, the subregion 2.1 is coated with an ion-conductive material, such as, for example, a sulfonated tetrafluoroethylene polymer. In this case, a semipermeable membrane layer 3, which is permeable to particles or ions below a predeterminable size, is formed.

Subsequently, as shown in FIG. 1C, the semipermeable membrane layer 3 is coated or printed with a catalyst layer 4. For example, precious metal-containing inks are used.

In the production of rolled goods, the subregions 2.1 of the individual sections A1 to An are first of all in the second method step with the

ion-conductive material coated. Subsequently, in the third method step, the membrane layers 3 thus formed are provided with the catalyst layer 4. In a subsequent separating step, the roll of plastic film K is cut and fed to the further manufacturing process.

In a fourth method step shown in FIG. 1D, the protruding edge region 2.2 of the amplifier layer 2 is arranged opposite one another

Frame elements 5 materially connected. The frame element 5 has an inner cutout surface 5.1, which overlaps with the catalyst layer 4. For example, the amplifier layer 2 is glued or welded to the frame element 5. In this case, the edge region 2.2 ensures surface contact with the respective frame element 5.

FIG. 3 shows the electrolyte membrane arrangement 1 in a sectional view. The

Amplifier layer 2 has an inner perforated portion 2.1. Of the

Part 2.1 of the amplifier layer 2 is on both sides with the semipermeable

Membrane layer 3 coated so that an ion exchange between the

opposite arranged catalyst layers 4 is made possible. Depending on the choice of the ion-conducting material, the semipermeable membrane layer 3 is permeable only to ions of a predeterminable size. According to various embodiments of the invention, the semipermeable membrane layer 3 according to the cell chemistry of

Fuel cell permeable to protons, hydroxide, oxonium, or radical dioxide ions.

The edge region 2.2 of the amplifier layer 2 is uncoated and protrudes beyond the edge of the coated region of the membrane layer 3 and the catalyst layer 4. This allows a simplified handling and processing of

Electrolyte membrane assembly 1 during manufacture, so that damage to the sensitive membrane layer 3 can be avoided.

FIG. 4 shows the electrolyte membrane arrangement 1 with the frame elements 5, which are materially connected to the protruding edge regions 2.2 of the amplifier layer 2. The two oppositely arranged frame elements 5 ensure the mechanical stability of the electrolyte membrane assembly 1. The inner one

Cut-out surface 5.1 of the frame member 5 overlaps with the region of the membrane layer 3 and the catalyst layer 4, so that this of the

Amplifying layer 2 raised portion of the membrane and catalyst layer 3, 4 rests positively on the frame member 5.

In each of FIGS. 3 and 4, a catalyst layer 4 is arranged on opposite sides of the amplifier layer 2. The two opposing catalyst layers 4 serve as electrodes of the fuel cell. At the catalyst layers 4 gas diffusion layers may be arranged in a manner not shown, so that the cell chemistry of the fuel cell corresponding gases of the anode and the cathode can be fed. LIST OF REFERENCE NUMBERS

1 electrolyte membrane assembly

2 amplifier layer

2.1 subarea

2.2 border area

3 membrane layer

4 catalyst layer

5 frame element

5.1 inner cut-out area

A1 to An section

K plastic film

Claims

claims

1. A multilayer electrolyte membrane arrangement (1) for a fuel cell, which has an amplifier layer (2) with a perforated subregion (2.1) and an edge region (2.2) surrounding the perforated subregion (2.1) at the edge, the perforated subregion (2.1) having an ion-conducting Material is coated so that a semi-permeable membrane layer (3) is formed.

2. A multilayer electrolyte membrane assembly (1) according to claim 1,

characterized in that the ionic conductive material is an ionomer.

3. A multilayer electrolyte membrane assembly (1) according to claim 1 or 2,

characterized in that the amplifier layer (2) consists of a

Plastic material is formed.

4. Multilayer electrolyte membrane arrangement (1) according to one of the preceding claims,

characterized in that at least one reinforcing frame element (5) is materially connected to the edge region (2.2) of the amplifier layer (2) in such a way that the frame element (5) is semipermeable

Membrane layer (3) rotates.

5. Multilayer electrolyte membrane arrangement (1) according to one of the preceding claims,

characterized in that the semipermeable membrane layer (3) is coated with a catalyst layer (4).

6. A method for producing an electrolyte membrane assembly (1) according to one of the preceding claims,

characterized in that in a first method step at least a partial region (2.1) of an amplifier layer (2) is perforated in such a way that an imperforate edge region (2.2) surrounding the partial region (2.1) is formed on the edge side and in a second process step the perforated partial region (2.1 ) is coated with an ion-conductive material to form a semipermeable membrane layer (3).

7. The method according to claim 6,

characterized in that in a third process step the

semipermeable membrane layer (3) is printed or coated with a catalyst layer (4).

8. The method according to claim 6 or 7,

characterized in that in a fourth method step at least one reinforcing frame element (5) with the edge region (2.2) of

Amplifier layer (2) is materially connected, so that the

Frame element (5), the semipermeable membrane layer (3) rotates edge.

9. The method according to claim 8,

characterized in that the edge region (2.2) of the amplifier layer (2) is glued or welded on both sides with two opposite frame elements (5). 0. Method according to one of claims 6 to 9,

characterized in that the amplifier layer (2) is made of roll material of a plastic film (K), wherein prior to the first process step or after the third process step, a separating step takes place, in which the roll goods are cut.