CN112928296A

CN112928296A - Membrane electrode assembly and fuel cell stack

Info

Publication number: CN112928296A
Application number: CN201911236174.7A
Authority: CN
Inventors: 罗宾逊·C·约瑟; 段伟康
Original assignee: Weishi Energy Technology Co Ltd
Current assignee: Weishi Energy Technology Co Ltd
Priority date: 2019-12-05
Filing date: 2019-12-05
Publication date: 2021-06-08
Anticipated expiration: 2039-12-05
Also published as: CN112928296B

Abstract

The present disclosure relates to a membrane electrode assembly, a fuel cell bipolar plate, a stack, and a fuel cell vehicle. Wherein, a membrane electrode subassembly includes: an electrolyte membrane; gas diffusion layers located at both sides of the electrolyte membrane, including metal meshes and metal foams; wherein the shapes of the contact surfaces of the metal net and the metal foam are matched with each other; and an electrode layer positioned between the electrolyte membrane and the metal mesh. According to the membrane electrode assembly, the metal foam is arranged on the outer side of the metal net, and the shapes of the contact surfaces of the metal net and the metal foam are set to be matched with each other, so that the contact resistance and the uneven contact pressure transmitted from the cathode plate and the anode plate to the interior of the membrane electrode assembly can be effectively reduced, and the even pressure distribution can be ensured.

Description

Membrane electrode assembly and fuel cell stack

Technical Field

The present disclosure generally relates to the field of fuel cell vehicles, and more particularly, to a membrane electrode assembly and a fuel cell stack.

Background

In a pem fuel cell, an electrolyte membrane, which can transport protons, is located between two different electrodes. The gaseous or liquid fuel is oxidized at the anode to produce hydrogen ions that are transported through the electrolyte membrane to the cathode, where they combine with oxygen at the cathode and the electrons transferred from the anode to the cathode through an external circuit to produce water.

A complete Membrane Electrode Assembly (MEA) is made up of a number of key components. The electrolyte membrane is sandwiched between two electrode layers differing in polarity and function, and the microstructure of the electrode layers is substantially porous, so that the electrode layers can transmit the gas fuel and the water produced by the electrochemical reaction. In addition, two microporous layer structures, called Gas Diffusion Layers (GDLs), are present adjacent to the two electrode layers. The gas diffusion layer not only has good electrical conductivity, but also redistributes the gaseous fuel that reacts at the electrode layers.

Currently, the gas diffusion layer is mostly made of carbon paper, but the resistance generated when the fuel passes through the gas diffusion layer made of carbon paper is a main source of reactant transmission resistance of the fuel cell.

To reduce the transport resistance of the fuel cell reactants, other materials (e.g., metal mesh) may be used as the gas diffusion layer instead of, or in addition to, carbon paper.

Fig. 1 is a schematic structural diagram of a conventional fuel cell stack 100, which includes an anode plate 101, a cathode plate 102, two symmetrically disposed metal meshes 103, two symmetrically disposed electrode layers 104, and an electrolyte membrane 105. In the fuel cell bipolar plate shown in fig. 1, the metal mesh is used as a gas diffusion layer, and since the metal mesh has high hardness, as can be seen from fig. 1, the surface of the metal mesh contacting the cathode plate and the anode plate is uneven, so that uneven contact pressure is generated, and the force is directly transmitted to the inside of the membrane electrode assembly, which causes the catalyst on the membrane electrode assembly to fall off, thereby affecting the performance of the fuel cell. For carbon paper, the thinner the paper, the more difficult and costly the paper can be made.

The statements in this background section merely represent techniques known to the public and are not, of course, representative of the prior art.

Disclosure of Invention

In order to solve the uneven contact pressure generated in the membrane electrode assembly when the metal mesh gas diffusion layer and the metal foam are used as the flow field, the present disclosure provides the following technical solutions.

The present disclosure provides a membrane electrode assembly comprising:

an electrolyte membrane;

gas diffusion layers located at both sides of the electrolyte membrane, including a metal mesh and metal foam; wherein the shapes of the contact surfaces of the metal mesh and the metal foam are matched with each other;

an electrode layer located between the electrolyte membrane and the metal mesh.

According to one aspect of the present disclosure, an upper coated microporous layer is disposed between the metal mesh and the catalyst of the electrode layer.

According to one aspect of the present disclosure, the contact surface of the metal mesh and the metal foam is wave-shaped.

According to one aspect of the present disclosure, the shapes of the contact surfaces of the metal mesh and the metal foam are fitted to each other by pressing the metal foam and the metal mesh together.

According to one aspect of the disclosure, the contact surfaces of the metal mesh and the metal foam are made to match in shape with each other using an etchant.

According to one aspect of the disclosure, the metal foam is selected from a nickel-based alloy or a titanium-based alloy.

The present disclosure also relates to a fuel cell stack comprising the membrane electrode assembly described above.

According to the membrane electrode assembly, the metal foam is arranged on the outer side of the metal net, and the shapes of the contact surfaces of the metal net and the metal foam are set to be matched with each other, so that the contact resistance and the uneven contact pressure transmitted from the cathode plate and the anode plate to the interior of the membrane electrode assembly can be effectively reduced, and the even pressure distribution can be ensured.

Drawings

The accompanying drawings, which are included to provide a further understanding of the disclosure, illustrate embodiments of the disclosure and together with the description serve to explain the disclosure and are not to limit the disclosure. In the drawings:

FIG. 1 is a schematic diagram of a prior art fuel cell stack;

FIG. 2 is a schematic structural view of a membrane electrode assembly according to an embodiment of the present disclosure;

fig. 3 is a schematic structural diagram of a fuel cell stack according to an embodiment of the present disclosure.

List of reference numerals:

100 fuel cell stack, 101 anode plate, 102 cathode plate, 103 metal mesh, 104 electrode layer, 105 electrolyte membrane;

200 membrane electrode assembly, 201 electrolyte membrane, 202 first electrode layer, 203 second electrode layer, 204 first metal mesh, 205 second metal mesh, 206 first metal foam, 207 second metal foam;

300 fuel cell stack, 301 electrolyte membrane, 302 first electrode layer, 303 second electrode layer, 304 first metal mesh, 305 second metal mesh, 306 first metal foam, 307 second metal foam, 308 cathode plate, 309 anode plate.

Detailed Description

In the following, only certain exemplary embodiments are briefly described. As those skilled in the art can appreciate, the described embodiments can be modified in various different ways, without departing from the spirit or scope of the present disclosure. Accordingly, the drawings and description are to be regarded as illustrative in nature, and not as restrictive.

In the description of the present disclosure, it is to be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "straight", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", and the like, indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed in a particular orientation, and be operated, and therefore should not be considered as limiting the present disclosure. Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first", "second", may explicitly or implicitly include one or more of the described features. In the description of the present disclosure, "a plurality" means two or more unless specifically limited otherwise.

Throughout the description of the present disclosure, it is to be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection, either mechanically, electrically, or otherwise in communication with one another; either directly or indirectly through intervening media, either internally or in any other relationship. The specific meaning of the above terms in the present disclosure can be understood by those of ordinary skill in the art as appropriate.

In the present disclosure, unless expressly stated or limited otherwise, the first feature "on" or "under" the second feature may comprise the first and second features being in direct contact, or may comprise the first and second features being in contact, not directly, but via another feature in between. Also, the first feature being "on," "above" and "over" the second feature includes the first feature being directly on and obliquely above the second feature, or merely indicating that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature includes the first feature being directly above and obliquely above the second feature, or simply meaning that the first feature is at a lesser level than the second feature.

The following disclosure provides many different embodiments or examples for implementing different features of the disclosure. To simplify the disclosure of the present disclosure, specific example components and arrangements are described below. Of course, they are merely examples and are not intended to limit the present disclosure. Moreover, the present disclosure may repeat reference numerals and/or reference letters in the various examples, which have been repeated for purposes of simplicity and clarity and do not in themselves dictate a relationship between the various embodiments and/or arrangements discussed. In addition, the present disclosure provides examples of various specific processes and materials, but one of ordinary skill in the art may recognize applications of other processes and/or use of other materials.

The preferred embodiments of the present disclosure will be described below with reference to the accompanying drawings, and it should be understood that the preferred embodiments described herein are merely for purposes of illustrating and explaining the present disclosure and are not intended to limit the present disclosure.

First embodiment

A first aspect of the present disclosure relates to a membrane electrode assembly, including: an electrolyte membrane; gas diffusion layers located at both sides of the electrolyte membrane, including metal meshes and metal foams; wherein the shapes of the contact surfaces of the metal net and the metal foam are matched with each other; and an electrode layer positioned between the electrolyte membrane and the metal foam.

According to the membrane electrode assembly, the metal foam is arranged on the outer side of the metal net, and the shapes of the contact surfaces of the metal net and the metal foam are set to be matched with each other, so that the contact resistance and the uneven contact pressure transmitted from the cathode plate and the anode plate to the interior of the membrane electrode assembly can be effectively reduced, and the even pressure distribution can be ensured. Preferred embodiments are described in detail below.

Fig. 2 is a schematic structural view illustrating a membrane electrode assembly 200 according to a preferred embodiment of the present disclosure, which includes: electrolyte membrane 201, first electrode layer 202, second electrode layer 203, first metal mesh 204, second metal mesh 205, first metal foam 206, and second metal foam 207. The first electrode layer 202 and the second electrode layer 203 are symmetrically arranged on the outer side of the electrolyte membrane 201, the first metal mesh 204 and the second metal mesh 205 are respectively arranged on the outer sides of the first electrode layer 202 and the second electrode layer 203, and the first metal foam 206 and the second metal foam 207 are respectively arranged on the outer sides of the first metal mesh 204 and the second metal mesh 205. The first expanded metal 204 and the first metal foam 206 form a first gas diffusion layer, and the second expanded metal 205 and the second metal foam 207 form a second gas diffusion layer. The contact surfaces of the first expanded metal 204 and the first metal foam 206 are shaped to match each other, and the contact surfaces of the second expanded metal 205 and the second metal foam 207 are shaped to match each other. In fig. 2, the shape of the contact surface of the first expanded metal 204 and the first metal foam 206, and the shape of the contact surface of the second expanded metal 205 and the second metal foam 207 are wavy. In the present disclosure, specific shapes of the metal mesh and the metal foam are not limited, as long as shapes of contact surfaces thereof are matched with each other, and the metal mesh and the metal foam can be designed according to actual conditions.

Because the metal foam with the mutually matched contact surface shapes is added, the contact pressure between the metal foam and the metal net can be more uniform, so that the metal net avoids generating uneven contact pressure between the metal net and the cathode plate and the anode plate under the action of external force, and the pressure acting on the catalyst layer can become more uniform.

The membrane electrode assembly design method is suitable for high current density conditions, can effectively eliminate mechanical failure caused by uneven contact pressure, and therefore helps to improve the durability and the service life of the membrane electrode assembly.

In a further preferred embodiment of the present disclosure, a microporous layer may be provided in the membrane electrode assembly, the microporous layer being located between the metal mesh and the catalyst of the electrode layer. The microporous layer preferably comprises carbon powder and a binder, more preferably comprises carbon powder and polytetrafluoroethylene. The pore diameter of the microporous layer is small, and the micropores on the microporous layer can thin the gas flow entering the catalytic layer and enable the gas flow to be more uniformly contacted with the catalyst. In the pore distribution of the microporous layer, micropores account for a large proportion, and water produced by the cell reaction is rapidly drawn into the microporous layer due to capillary action. Because the microporous layer has hydrophobicity, the entered water is discharged quickly, the possibility of flooding the electrode is reduced, and the performance and the service life of the fuel cell are improved.

The membrane electrode assembly shown in figure 2 may be constructed by pressing a metal foam and a metal mesh together or by using an etchant to form the interface of the metal mesh and the metal foam with a shape that matches each other, although other techniques may be used in the industry. The detailed description of the method is omitted here.

The metal foam may be made of a nickel-based alloy or a titanium-based alloy, but of course, other materials may be used so long as the requirements of the present disclosure are met and the performance of the fuel cell is ensured.

Second embodiment

A second aspect of the present disclosure relates to a fuel cell stack including a plurality of the above membrane electrode assemblies.

As the durability and life of the membrane electrode assembly described above is improved, the performance of a fuel cell stack made therefrom is correspondingly improved, and will not be described further herein.

Fig. 3 is a schematic diagram of a preferred fuel cell stack according to the present disclosure. In fig. 3, a fuel cell stack 300 includes: electrolyte membrane 301, first electrode layer 302, second electrode layer 303, first metal mesh 304, second metal mesh 305, first metal foam 306, second metal foam 307, cathode plate 308, anode plate 309. The first electrode layer 302 and the second electrode layer 303 are symmetrically arranged on the outer side of the electrolyte membrane 301, the first metal mesh 304 and the second metal mesh 305 are respectively arranged on the outer sides of the first electrode layer 302 and the second electrode layer 303, and the first metal foam 306 and the second metal foam 307 are respectively arranged on the outer sides of the first metal mesh 304 and the second metal mesh 305. The cathode plate 308 and the anode plate 309 are disposed outside the first metal foam 306 and the second metal foam 307, respectively.

The first expanded metal 304 and the first metal foam 306 form a first gas diffusion layer, and the second expanded metal 305 and the second metal foam 307 form a second gas diffusion layer. The contact surfaces of the first expanded metal 304 and the first metal foam 306 are shaped to match each other, and the contact surfaces of the second expanded metal 305 and the second metal foam 307 are shaped to match each other. In fig. 3, the shape of the contact surface of the first expanded metal 304 and the first metal foam 306, and the shape of the contact surface of the second expanded metal 305 and the second metal foam 307 are wavy. In fig. 3, the cathode plate 308 and the anode plate 309 are formed in a parallel plate-like structure, but may have other shapes, such as a wave shape in fig. 1.

In a further preferred embodiment of the present disclosure, when the anode plate and the cathode plate are in a parallel plate shape and no flow channel is provided, the flow channel defined by the anode plate and/or the cathode plate and the membrane electrode assembly may be a parallel flow channel, a serpentine flow channel, an interdigitated flow channel, a needle-shaped flow channel or a bionic flow channel.

Since the contact pressure between the metal foam and the metal mesh is uniform, the shape of the flow channels in the fuel cell bipolar plate is not limited any more, and of course, the shape of the fuel cell bipolar plate in the present disclosure is not limited to the above-mentioned shape and may be determined according to actual needs.

The above description is only exemplary of the present disclosure and should not be taken as limiting the disclosure, as any modification, equivalent replacement, or improvement made within the spirit and principle of the present disclosure should be included in the scope of protection of the present disclosure.

Finally, it should be noted that: although the present disclosure has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that changes may be made in the embodiments and/or equivalents thereof without departing from the spirit and scope of the disclosure. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present disclosure should be included in the protection scope of the present disclosure.

Claims

1. A membrane electrode assembly, comprising:

an electrolyte membrane;

the gas diffusion layers are positioned on two sides of the electrolyte membrane and comprise metal meshes and metal foams, wherein the shapes of contact surfaces of the metal meshes and the metal foams are matched with each other;

an electrode layer located between the electrolyte membrane and the metal mesh.

2. A membrane electrode assembly according to claim 1, wherein a microporous layer is provided between the metal mesh and the catalyst of the electrode layer.

3. A membrane electrode assembly according to claim 1, wherein the contact surfaces of the metal mesh and the metal foam are undulated in shape.

4. A membrane electrode assembly according to claim 1, wherein the shapes of the contact surfaces of the metal mesh and the metal foam are adapted to each other by pressing the metal foam and the metal mesh together.

5. A membrane electrode assembly according to claim 1, wherein the contact surfaces of the metal mesh and the metal foam are shaped to fit each other using an etchant.

6. The membrane electrode assembly of claim 1, wherein the metal foam is selected from a nickel-based alloy or a titanium-based alloy.

7. A fuel cell stack comprising the membrane electrode assembly according to any one of claims 1 to 6.