CN113782752A

CN113782752A - Membrane electrode, fuel cell and vehicle

Info

Publication number: CN113782752A
Application number: CN202111121013.0A
Authority: CN
Inventors: 温翔龙; 张潇丹; 苗佩宇; 姜海林
Original assignee: Beijing Sinohytec Co Ltd
Current assignee: Beijing Sinohytec Co Ltd
Priority date: 2021-09-24
Filing date: 2021-09-24
Publication date: 2021-12-10

Abstract

The invention relates to the technical field of fuel cells, in particular to a membrane electrode, a fuel cell and a vehicle, wherein the membrane electrode comprises a gas diffusion layer and a catalyst layer, the gas diffusion layer comprises a microporous layer and a substrate layer, and the microporous layer is positioned between the catalyst layer and the substrate layer; the microporous layer comprises a hydrophilic part and a hydrophobic part, and the hydrophilic part is distributed according to a preset position; according to the invention, the hydrophilic part can absorb water from the catalyst layer more easily by additionally arranging the microporous layer of the hydrophilic part, and the diffusion layer still has considerable hydrophobicity due to hydrophobicity, so that the water cannot be accumulated in the diffusion layer; the gas diffusion layer is subjected to hydrophilic treatment on partial areas on the basis of guaranteeing the hydrophobic performance of the gas diffusion layer on the whole, the water management inside the membrane electrode is optimized, the membrane electrode is prevented from flooding, and the performance of the fuel cell is improved.

Description

Membrane electrode, fuel cell and vehicle

Technical Field

The invention relates to the technical field of fuel cells, in particular to a membrane electrode, a fuel cell and a vehicle.

Background

Proton Exchange Membrane Fuel Cells (PEMFCs) are high-efficiency energy conversion devices that can directly convert chemical energy stored in hydrogen fuel and oxygen into electrical energy by means of electrochemical reaction, have the characteristics of environmental protection, high specific energy, low-temperature rapid start and high smooth operation, and are considered as ideal power sources for replacing internal combustion engines. In recent years, various governments and companies have been working on the development of fuel cell vehicles, and as represented by japan, Mirai hydrogen fuel cell vehicles have been introduced, and domestic fuel cell companies have also successively introduced their own fuel cell products.

The Membrane Electrode (MEA) is the core component of the proton exchange membrane fuel cell, provides micro-channels for multi-phase substance transfer and electrochemical reaction sites for the PEMFC, and the performance of the PEMFC determines the performance of the PEMFC. The MEA mainly comprises an anode Gas Diffusion Layer (GDL), a cathode Catalyst Layer (CL) and a Proton Exchange Membrane (PEM), wherein the Gas Diffusion Layer (GDL) consists of a substrate layer and a microporous layer which is attached to the substrate layer and consists of carbon powder. In the working process of the fuel cell, anode hydrogen and cathode oxygen (air) react on a cathode catalyst layer to generate water, the water is gradually discharged out of a membrane electrode into a flow field through the concentration gradient of the water and the driving of gas diffusion, and finally the water is finally discharged out of the fuel cell through gas convection. However, when the fuel cell is operated under a high current density condition, the generated water cannot be discharged in time, so that the catalyst in the catalyst layer is flooded by water and cannot participate in the reaction, thereby affecting the performance of the fuel cell.

In order to facilitate the discharge of water, the common idea is to reduce the water retention capacity of the gas diffusion layer, i.e. to increase the hydrophobicity of the diffusion layer, so that water is not easy to stay in the diffusion layer and is easier to discharge; it has been found that it is not very effective to improve the hydrophobic capacity of the diffusion layer.

Referring to fig. 1, water generated by the fuel cell firstly enters the gas diffusion layer from the catalyst layer and finally enters the flow field to be finally discharged out of the fuel cell, and the water is prevented from entering the diffusion layer from the catalyst layer due to the fact that the hydrophobicity of the diffusion layer is improved, so that flooding caused in the first step is not facilitated; some of the ideas of hydrophilic treatment are to perform hydrophilic treatment on the microporous layer or the whole diffusion layer, which can improve the water retention capacity of the whole diffusion layer, and is not beneficial to the water flooding caused by the step two.

Disclosure of Invention

The technical problem to be solved by the invention is as follows: the membrane electrode, the fuel cell and the vehicle realize that water smoothly enters the gas diffusion layer from the catalyst layer, is finally discharged into the flow field and is finally discharged out of the fuel cell, prevent the membrane electrode from flooding and finally improve the performance of the fuel cell.

In order to solve the above technical problems, a first technical solution adopted by the present invention is:

a membrane electrode comprising a gas diffusion layer and a catalytic layer, the gas diffusion layer comprising a microporous layer and a substrate layer, the microporous layer being located between the catalytic layer and the substrate layer;

the microporous layer includes hydrophilic portions and hydrophobic portions, and the hydrophilic portions are distributed according to a predetermined position.

Preferably, the hydrophilic portion forms a plurality of continuous serpentine traces, and the other portion of the microporous layer is a hydrophobic portion.

Preferably, the hydrophilic portion forms two continuous serpentine traces.

Preferably, the hydrophilic part of the microporous layer is obtained by treating the microporous layer with a surfactant at predetermined positions.

Preferably, the surfactant is a Nafion membrane solution.

Preferably, the hydrophobic portion of the microporous layer is obtained by treating one of dodecyl mercaptan, a PTFE solution, or a PVDF solution.

Preferably, the microporous layer is prepared by respectively preparing hydrophilic carbon powder slurry and hydrophobic carbon powder slurry, the hydrophobic carbon powder slurry is formed into a hydrophobic part, a preset position is reserved on the hydrophobic part, and the hydrophilic carbon powder slurry is distributed according to a preset setting to form a hydrophilic part.

In order to solve the above technical problem, the second technical solution adopted by the present invention is:

a fuel cell comprises a bipolar plate and the membrane electrode, wherein the bipolar plate, a gas diffusion layer and a catalyst layer are sequentially arranged, a flow field is arranged on one surface of the bipolar plate facing the gas diffusion layer, and the projection of the flow field on a microporous layer is overlapped with or larger than a hydrophilic part of the microporous layer.

Preferably, the projection of the flow field on the microporous layer is a plurality of continuous serpentine tracks.

In order to solve the above technical problems, the third technical solution adopted by the present invention is:

a vehicle comprising the membrane electrode described above and/or the fuel cell described above.

The invention has the beneficial effects that: by adding the microporous layer with the hydrophilic part, the hydrophilic part can absorb water from the catalytic layer more easily, and the hydrophobic part enables the diffusion layer to still have considerable hydrophobicity without causing water accumulation on the diffusion layer; the gas diffusion layer is subjected to hydrophilic treatment on partial areas on the basis of guaranteeing the hydrophobic performance of the gas diffusion layer on the whole, the water management inside the membrane electrode is optimized, the membrane electrode is prevented from flooding, and the performance of the fuel cell is improved. The projection of the flow field on the microporous layer is overlapped with or larger than the hydrophilic part of the microporous layer, the flow field is actually a groove for accommodating gas flow, the flow field is overlapped with the hydrophilic part, so that the reaction gas is most sufficient, and the water generated by the chemical reaction is most dense, and the treatment has the advantages that the product water can more easily enter a Gas Diffusion Layer (GDL) from the catalytic layer (the hydrophilic part causes the water to be rapidly taken out from the catalytic layer), the drainage of the final liquid water is convenient, and the optimal management of the reaction water is realized.

Drawings

FIG. 1 is an explanatory diagram of the prior art;

fig. 2 is a schematic diagram of a membrane electrode and a sectional diagram of a middle portion (for convenience of illustration, the sectional diagram portion shows a bipolar plate and a proton exchange membrane together, and a projection line and a hydrophilic portion are marked by black frames);

FIG. 3 is a schematic view of a gas diffusion layer of a membrane electrode according to an embodiment of the present invention;

FIG. 4 is a schematic view of a bipolar plate of a fuel cell in accordance with an embodiment of the present invention;

description of reference numerals: 1. a membrane electrode; 11. a gas diffusion layer; 111. a microporous layer; 112. a base layer; 113. a hydrophilic moiety; 114. a hydrophobic moiety; 12. a catalytic layer; 13. a proton exchange membrane; 2. a bipolar plate; 21. a flow field; 3. and (4) projecting the line.

Detailed Description

In order to explain technical contents, achieved objects, and effects of the present invention in detail, the following description is made with reference to the accompanying drawings in combination with the embodiments.

Example one

Referring to fig. 2 and fig. 3, a membrane electrode 1 includes a gas diffusion layer 11 and a catalytic layer 12, the gas diffusion layer 11 includes a microporous layer 111 and a substrate layer 112, the microporous layer 111 is located between the catalytic layer 12 and the substrate layer 112;

the microporous layer 111 includes hydrophilic portions 113 and hydrophobic portions 114, and the hydrophilic portions 113 are distributed according to a predetermined position.

The hydrophilic portions 113 form two continuous serpentine traces and the other portions of the microporous layer 111 are hydrophobic portions 114.

The hydrophilic portion 113 of the microporous layer 111 is obtained by treating the microporous layer 111 with a surfactant at predetermined positions. The surfactant is Nafion membrane solution.

The hydrophobic portion 114 of the microporous layer 111 is obtained by treating one of dodecyl mercaptan, a PTFE solution, or a PVDF solution.

When the microporous layer 111 is prepared, hydrophilic carbon powder slurry and hydrophobic carbon powder slurry are respectively prepared, the hydrophobic carbon powder slurry is formed into a hydrophobic part 114, a preset position is reserved on the hydrophobic part, and the hydrophilic carbon powder slurry is distributed according to a preset setting to form a hydrophilic part 113.

Example two

A membrane electrode 1 comprises a gas diffusion layer 11 and a catalytic layer 12, wherein the gas diffusion layer 11 comprises a microporous layer 111 and a substrate layer 112, and the microporous layer 111 is positioned between the catalytic layer 12 and the substrate layer 112;

The hydrophilic portion 113 forms three continuous traces, and the other portion of the microporous layer 111 is a hydrophobic portion 114.

EXAMPLE III

Referring to fig. 4, a fuel cell includes a bipolar plate 2 and a membrane electrode 1 according to the first embodiment or the second embodiment, the bipolar plate 2, a gas diffusion layer 11, a catalyst layer 12, and a proton exchange membrane 3 are sequentially disposed, a flow field 21 is disposed on a surface of the bipolar plate 2 facing the gas diffusion layer 11, and a projection of the flow field 21 on a microporous layer 111 overlaps with a hydrophilic portion 113 of the microporous layer 111.

Example four

A vehicle comprising the membrane electrode 1 according to embodiment one or embodiment two and/or the fuel cell according to embodiment three.

The above description is only an embodiment of the present invention, and not intended to limit the scope of the present invention, and all equivalent changes made by using the contents of the present specification and the drawings, or applied directly or indirectly to the related technical fields, are included in the scope of the present invention.

Claims

1. A membrane electrode comprising a gas diffusion layer and a catalytic layer, wherein the gas diffusion layer comprises a microporous layer and a substrate layer, the microporous layer being located between the catalytic layer and the substrate layer;

2. The membrane electrode of claim 1, wherein said hydrophilic portion forms a plurality of continuous serpentine traces and the other portion of said microporous layer is a hydrophobic portion.

3. The membrane electrode of claim 2, wherein said hydrophilic portion forms two continuous serpentine runs.

4. The membrane electrode according to claim 1, wherein the hydrophilic portion of the microporous layer is obtained by treating the microporous layer with a surfactant at a predetermined position.

5. The membrane electrode assembly of claim 4, wherein the surfactant is a Nafion membrane solution.

6. The membrane electrode of claim 4, wherein the hydrophobic portion of the microporous layer is treated with one of dodecyl mercaptan, PTFE solution, or PVDF solution.

7. The membrane electrode of claim 1, wherein the microporous layer is prepared by separately preparing hydrophilic carbon powder slurry and hydrophobic carbon powder slurry, the hydrophobic carbon powder slurry is formed into a hydrophobic part, a preset position is reserved on the hydrophobic part, and the hydrophilic carbon powder slurry is distributed according to a preset arrangement to form a hydrophilic part.

8. A fuel cell comprising a bipolar plate and the membrane electrode of any one of claims 1 to 7, wherein the bipolar plate, the gas diffusion layer and the catalytic layer are arranged in this order, a flow field is provided on a side of the bipolar plate facing the gas diffusion layer, and a projection of the flow field on the microporous layer overlaps with or is larger than a hydrophilic portion of the microporous layer.

9. The fuel cell of claim 8, wherein the projection of the flow field onto the microporous layer is a number of continuous serpentine traces.

10. A vehicle comprising a membrane electrode according to any one of claims 1 to 7 and/or a fuel cell according to any one of claims 8 to 9.