DE102011106767B3 - Multilayer electrolyte membrane arrangement for fuel cell, has strengthening layer including perforated subregion, which is coated with ion-conductive material so that semipermeable membrane layer is formed - Google Patents

Abstract

A multilayer electrolyte membrane arrangement (1) for a fuel cell has a reinforcing layer (2) with a perforated sub-area (2.1) and an imperforate edge area (2.2) surrounding the perforated sub-area (2.1). The perforated sub-area (2.1) is coated with an ion-conductive material so that a semipermeable membrane layer (3) is formed.

Description

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.

Fuel cells are known from the prior art, which have 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 to operate an electrical load connected between the anode and the cathode.

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.

From the US 2005/0227132 A1 For example, a multilayered electrolyte membrane assembly is known which has a porous enhancer layer with an aperture ratio between 50% and 90%. The amplifier layer is completely incorporated in a polymer electrolyte membrane. In particular, the amplifier layer and the polymer electrolyte membrane arranged thereon completely overlap. The polyelectrolyte membrane is coated on both sides with a catalyst layer which has a carbon powder which serves as a carrier material for a catalytic metal such as platinum.

The invention is based on the object to provide an improved over the prior art electrolyte membrane assembly and an improved method for producing the electrolyte membrane assembly.

The object is achieved by an electrolyte membrane assembly with the features of claim 1 and by a method for producing the electrolyte membrane assembly with the characterizing features of claim 6.

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

A multilayer electrolyte membrane arrangement for a fuel cell has an amplifier layer with a perforated subregion and an imperforate edge region surrounding the perforated subregion at the edge. The perforated portion is coated with an ion-conductive material, so that a semi-permeable 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 of the ionic conductive material are very thin (10-30 μm) and mechanically sensitive. Therefore, such polymer electrolyte membrane can only be laboriously glued or welded, which is also associated with the risk of damaging the polymer electrolyte membrane. 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 can be glued and / or welded quickly and easily to other components of the fuel cell. Preferably, the amplifier layer is formed from a low cost material to reduce manufacturing costs.

Preferably, the ionically 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 to 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 formed of a low-cost plastic material, such as in particular a polymer, which in comparison to the ion-conductive material has an increased mechanical, thermal and / or chemical Robustness. 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 can be printed with the catalyst layer. 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 fuel cell. The semipermeable membrane layer is in particular coated with a catalyst layer for forming 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 for producing the electrolyte membrane arrangement, according to the invention, in a first method step, at least one subregion of an amplifier layer is perforated such 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 a 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 is materially connected to the edge region of the amplifier layer. 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 is adhesively bonded or welded on both sides with two opposite frame elements in order to advantageously increase the mechanical robustness of the electrolyte membrane arrangement.

According to a preferred embodiment, the reinforcing layer is made of roll material of a plastic film. In order to produce the electrolyte membrane arrangement, either before the first method step or after the third method step, a separating step takes place in which the rolled goods are cut. It is particularly advantageous from a procedural point of view if the perforation of the subregion, the application of the ion-conductive material and the subsequent coating with the catalyst layer are already carried out on the roll material of the plastic film. The perforated and coated plastic film is then cut to size and in particular welded or glued to the frame member to form the electrolyte membrane assembly. The processing of roll goods enables 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.

1A to 1D schematically illustrate process steps for producing an electrolyte membrane assembly.

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

3 shows the electrolyte membrane assembly in a sectional view.

4 shows a sectional view of the electrolyte membrane assembly with bordering frame elements.

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

1A to 1D schematically illustrate individual process steps for producing an electrolyte membrane assembly 1 ,

1A shows an amplifier layer 2 for a multilayered electrolyte membrane assembly 1 , An inner subarea 2.1 the amplifier layer 2 is perforated in a first process step by means of suitable punching or perforating tools. The amplifier layer 2 has a peripheral edge area 2.2 on, which is unperforated and the perforated portion 2.1 rotates at the edge.

The amplifier layer 2 For example, from single sheets of a plastic film K or roll of the plastic film K, as in 2 represented, manufactured. 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 corresponding to the unperforated edge area 2.2 is surrounded.

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 process step, as in 1B shown, the subarea 2.1 coated with an ionic conductive material, such as a sulfonated tetrafluoroethylene polymer. This is a semi-permeable membrane layer 3 , which is permeable to particles or ions below a predeterminable size, formed.

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

In the production of roll goods are corresponding to the sub-areas 2.1 the individual sections A1 to An first coated in the second process step with the ion-conductive material. Subsequently, in the third process step, the membrane layers thus formed 3 with the catalyst layer 4 Mistake. In a subsequent separating step, the roll of plastic film K is cut and fed to the further manufacturing process.

In an in 1D shown fourth process step is the protruding edge region 2.2 the amplifier layer 2 with oppositely arranged frame elements 5 cohesively connected. The frame element 5 has an inner cut surface 5.1 , which deals with the catalyst layer 4 covered up. For example, the amplifier layer 2 with the frame element 5 glued or welded. It represents the border area 2.2 the surface contact with the respective frame element 5 for sure.

3 shows the electrolyte membrane assembly 1 in a sectional view. The amplifier layer 2 has an inner perforated portion 2.1 on. The subarea 2.1 the amplifier layer 2 is bilateral with the semipermeable membrane layer 3 coated so that an ion exchange between the oppositely arranged catalyst layers 4 is possible. Depending on the choice of ion-conductive material is the semipermeable membrane layer 3 permeable only to ions of a predefinable size. According to various embodiments of the invention, the semipermeable membrane layer 3 according to the cell chemistry of the fuel cell for proton, hydroxide, oxonium, or radical dioxide ions permeable.

The border area 2.2 the amplifier layer 2 is uncoated and protrudes on the edge over the coated area of the membrane layer 3 and the catalyst layer 4 out. This allows for simplified handling and processing of the electrolyte membrane assembly 1 during manufacture, causing damage to the delicate membrane layer 3 can be avoided.

4 shows the electrolyte membrane assembly 1 with the frame elements 5 , which with the protruding edge areas 2.2 the amplifier layer 2 are connected cohesively. The two oppositely arranged frame elements 5 provide the mechanical stability of the electrolyte membrane assembly 1 for sure. The inner cut-out area 5.1 of the frame element 5 overlaps with the area of the membrane layer 3 and the catalyst layer 4 so that this from the amplifier layer 2 raised region of the membrane and catalyst layer 3 . 4 positively on the frame element 5 is applied.

In 3 and 4 each is a catalyst layer 4 on opposite sides of the amplifier layer 2 arranged. The two opposite catalyst layers 4 serve as electrodes of the fuel cell. At the catalyst layers 4 can be arranged in a manner not shown gas diffusion layers, 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

promoting layer

2.1

subregion

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 (10)

Multilayer electrolyte membrane assembly ( 1 ) for a fuel cell which has an amplifier layer ( 2 ) with a perforated portion ( 2.1 ) and a perforated portion ( 2.1 ) edge area surrounding ( 2.2 ), wherein the perforated portion ( 2.1 ) is coated with an ion-conductive material, so that a semipermeable membrane layer ( 3 ) is formed. Multilayer electrolyte membrane assembly ( 1 ) according to claim 1, characterized in that the ion-conductive material is an ionomer. Multilayer electrolyte membrane assembly ( 1 ) according to claim 1 or 2, characterized in that the amplifier layer ( 2 ) is formed of a plastic material. Multilayer electrolyte membrane assembly ( 1 ) according to one of the preceding claims, characterized in that at least one reinforcing frame element ( 5 ) with the edge area ( 2.2 ) of the amplifier layer ( 2 ) is materially connected such that the frame element ( 5 ) the semipermeable membrane layer ( 3 ) rotates. Multilayer electrolyte membrane assembly ( 1 ) according to one of the preceding claims, characterized in that the semipermeable membrane layer ( 3 ) with a catalyst layer ( 4 ) is coated. Method for producing an electrolyte membrane arrangement ( 1 ) according to one of the preceding claims, characterized in that in a first method step at least one subregion ( 2.1 ) an amplifier layer ( 2 ) is perforated such that the subregion ( 2.1 ) at the edge surrounding, unperforated border area ( 2.2 ) is formed and in a second process step, the perforated portion ( 2.1 ) with an ion-conductive material for forming a semipermeable membrane layer ( 3 ) is coated. A method according to claim 6, characterized in that in a third method step, the semipermeable membrane layer ( 3 ) with a catalyst layer ( 4 ) is printed or coated. 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 area ( 2.2 ) of the amplifier layer ( 2 ) is materially connected, so that the frame element ( 5 ) the semipermeable membrane layer ( 3 ) at the edge, Method according to claim 8, characterized in that the edge region ( 2.2 ) of the amplifier layer ( 2 ) on both sides with two opposing frame elements ( 5 ) is glued or welded. 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 singulation step takes place in which the roll goods are cut.

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