CN113964356A

CN113964356A - Fuel cell membrane electrode, membrane electrode preparation method, fuel cell system and vehicle

Info

Publication number: CN113964356A
Application number: CN202111142692.XA
Authority: CN
Inventors: 龙鹏; 李玉鹏; 王江林
Original assignee: Sany Automobile Manufacturing Co Ltd
Current assignee: Sany Automobile Manufacturing Co Ltd
Priority date: 2021-09-28
Filing date: 2021-09-28
Publication date: 2022-01-21

Abstract

The invention relates to the technical field of fuel cells and provides a fuel cell membrane electrode, a membrane electrode preparation method, a fuel cell system and a vehicle, wherein the fuel cell membrane electrode comprises: a catalyst layer; a gas diffusion layer provided on at least one side of the catalyst layer; the polar plate is located the one side that gas diffusion layer deviates from the catalyst layer, and gas diffusion layer's material is elastic material, polar plate, gas diffusion layer and catalyst layer formula structure as an organic whole. In the technical scheme of the invention, the gas diffusion layer is made of elastic materials, so that the gas diffusion layer has better air permeability and telescopic performance, greatly reduces the possibility of separation, ensures that the galvanic pile keeps stable in different operating environments and working conditions, and is beneficial to improving the stability and durability of the fuel cell. In addition, the polar plate, the gas diffusion layer and the catalyst layer are of an integrated structure, so that gaps between the polar plate and the gas diffusion layer and gaps between the gas diffusion layer and the catalyst layer can be reduced, and the stability and the durability of the fuel cell can be further improved.

Description

Fuel cell membrane electrode, membrane electrode preparation method, fuel cell system and vehicle

Technical Field

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

Background

During operation of the fuel cell membrane electrode, the proton exchange membrane expands and contracts with changes in humidity and temperature. Due to the expansion and contraction of the proton exchange membrane, the expansion coefficients are different, and the position of the two polar plates is limited, the in-plane compression and stretching of damp and hot can generate pressure. As shown in fig. 1, the conventional gas diffusion layer 130' is brittle and easily separated from the electrode plate or catalyst layer by internal stress such as compressive stress, freezing, thawing or swelling, thereby causing mechanical degradation, and particularly after several thermal-humidity cycles, the thermal-humidity stress affects the life and performance of the fuel cell.

Disclosure of Invention

In order to solve or improve the technical problem that a gas diffusion layer is easy to separate from a polar plate or a catalyst layer, the invention aims to provide a fuel cell membrane electrode.

Another object of the present invention is to provide a membrane electrode preparation method.

It is another object of the present invention to provide a fuel cell system.

It is another object of the present invention to provide a vehicle.

To achieve the above object, a first aspect of the present invention provides a fuel cell membrane electrode comprising: a catalyst layer; a gas diffusion layer provided on at least one side of the catalyst layer; the polar plate is located the one side that gas diffusion layer deviates from the catalyst layer, and gas diffusion layer's material is elastic material, and polar plate, gas diffusion layer and catalyst layer produce formula structure as an organic whole through chemical vapor deposition's mode.

According to the embodiment of the fuel cell membrane electrode provided by the invention, the gas diffusion layer is made of elastic materials, so that the air permeability and the telescopic performance are better, and when the internal stress of a galvanic pile is enhanced, the gas diffusion layer is effectively contracted; when the stress is weakened, the gas diffusion layer relaxes, so that the stress in the electric pile can be in a proper range, the possibility of separation between the gas diffusion layer and the catalyst layer or between the gas diffusion layer and the polar plate is greatly reduced, the electric pile is ensured to be stable under different operating environments and working conditions, and the stability and the durability of the fuel cell are improved. In addition, the polar plate, the gas diffusion layer and the catalyst layer are of an integrated structure, so that gaps between the polar plate and the gas diffusion layer and gaps between the gas diffusion layer and the catalyst layer can be reduced, and the stability and the durability of the fuel cell can be further improved.

A fuel cell is a chemical device that directly converts chemical energy of fuel into electrical energy, and is also called an electrochemical generator. Fuel cells are the fourth power generation technology following hydroelectric, thermal, and nuclear power generation. The fuel cell converts the Gibbs free energy in the chemical energy of the fuel into electric energy through electrochemical reaction, and is not limited by Carnot cycle effect, so the efficiency is higher, and the fuel cell uses the fuel and oxygen as raw materials, has no mechanical transmission part, discharges extremely little harmful gas and has long service life. A fuel cell membrane electrode, i.e. a membrane electrode assembly, also called membrane electrode, can be understood as an electrode equipped with a membrane assembly in its structure, which is a key core component of fuel cell power generation. Specifically, the fuel cell membrane electrode includes a catalyst layer, a gas diffusion layer, and a plate. Wherein, further, gas diffusion layer locates at least one side of catalyst layer, and the polar plate is located gas diffusion layer and is kept away from one side of catalyst layer. The gas diffusion layer plays a role in supporting the catalyst layer and stabilizing the electrode structure in the fuel cell membrane electrode, and can also provide a gas channel, an electronic channel and a drainage channel for electrode reaction. The material of the gas diffusion layer satisfies the following conditions: uniform porous structure and good air permeability; the resistivity is low, and the electron conductivity is strong; the structure is compact and the surface is smooth, so that the contact resistance is reduced, and the conductivity is improved; has certain mechanical strength; proper hydrophilic and hydrophobic balance; has chemical stability and thermal stability; the manufacturing cost is low, and the cost performance is high.

Typically, the number of catalyst layers is two, and the two catalyst layers are located on both sides of the proton exchange membrane. The two catalyst layers are divided into an anode catalyst layer and a cathode catalyst layer. In addition, the number of the polar plate and the gas diffusion layers is also two, the two polar plates are divided into an anode polar plate and a cathode polar plate, one gas diffusion layer is positioned between the anode polar plate and the anode catalyst layer, and the other gas diffusion layer is positioned between the cathode polar plate and the cathode catalyst layer. The hydrogen gas reaches the anode through a gas flow field on the anode plate, through a gas diffusion layer, and to an anode catalyst layer. The hydrogen gas is adsorbed on the catalyst layer and is decomposed into two hydrogen ions, namely protons H under the action of the catalyst platinum⁺And two electrons are released, this process is called the anodic oxidation process of hydrogen, and the reactions taking place at the anode are: h₂＝2H⁺+2 e. At the other end of the cell, oxygen or air passes through the gas flow field on the cathode plate to the cathode, through the diffusion layer on the electrode to the cathode catalyst layer where it is adsorbed, while hydrogen ions pass through the electrolyte to the cathode, and electrons also pass through an external circuit to the cathode. Under the action of the cathode catalyst, oxygen, hydrogen ions and electrons react to generate water, and the process is called as the cathode reduction process of oxygen. The reactions occurring at the anode were: 1/2O₂+2H⁺+2e＝H₂And O. The overall chemical reaction formula is: h₂+1/2O₂＝H₂And O, meanwhile, the electrons form current under the connection of an external circuit, electric energy can be output to a load through proper connection, and generated water is discharged along with reaction tail gas.

Furthermore, the gas diffusion layer is made of elastic materials, on one hand, the gas diffusion layer is of a porous structure and has better air permeability, and a gas channel, an electronic channel and a drainage channel can be provided for electrode reaction; on the other hand, the gas diffusion layer is made of elastic materials, so that the expansion and contraction performance is better; furthermore, the gas diffusion layer is made of a carbon material, so that the material performance is ensured, the gas diffusion layer has enough mechanical strength, and the gas diffusion layer plays a role in supporting the catalyst layer and stabilizing the electrode structure.

During operation of the fuel cell membrane electrode, the proton exchange membrane expands and contracts with changes in humidity and temperature. Due to the expansion and contraction of the proton exchange membrane, the expansion coefficients are different, and the position of the two polar plates is limited, the in-plane compression and stretching of damp and hot can generate pressure. The traditional gas diffusion layer has strong brittleness and is easy to separate from a polar plate or a catalyst layer under the action of internal stress such as compression stress, freezing, melting or swelling and the like, so that mechanical attenuation is caused, and particularly after a plurality of damp-heat cycles, the damp-heat stress can influence the service life and the performance of a fuel cell.

In the technical scheme defined by the application, the gas diffusion layer is made of an elastic material, so that the air permeability and the telescopic performance are better, and when the internal stress of the galvanic pile is enhanced, the gas diffusion layer is effectively contracted; when the stress is weakened, the gas diffusion layer relaxes, so that the stress in the electric pile can be in a proper range, the possibility of separation between the gas diffusion layer and the catalyst layer or between the gas diffusion layer and the polar plate is greatly reduced, the electric pile is ensured to be stable under different operating environments and working conditions, and the stability and the durability of the fuel cell are improved.

Further, the polar plate, the gas diffusion layer and the catalyst layer are of an integrated structure. The polar plate, the gas diffusion layer and the catalyst layer are produced by chemical vapor deposition, on one hand, the connection strength between the polar plate and the gas diffusion layer and between the gas diffusion layer and the catalyst layer is favorably improved, and the gaps between the polar plate and the gas diffusion layer and between the gas diffusion layer and the catalyst layer are reduced as much as possible; on the other hand, the number of parts is reduced, and the assembly efficiency of workers can be improved. Chemical vapor deposition is a chemical technology, which is a method for generating a film by performing a chemical reaction on the surface of a substrate by using one or more gas-phase compounds or simple substances containing film elements.

In addition, the technical scheme provided by the invention can also have the following additional technical characteristics:

in the above technical solution, the gas diffusion layer is any one of an elastic carbon nanotube porous membrane, an elastic graphene porous membrane, an elastic carbon fiber porous membrane, an elastic carbon felt, or an elastic carbon paper.

In this embodiment, the gas diffusion layer is formed as an elastic carbon nanotube porous membrane, so that the gas diffusion layer has a uniform porous thin-layer structure and is excellent in stretchability, electrical conductivity, chemical stability, and thermal stability. In addition, the carbon nano tube is made of nano material and has the advantages of light weight and the like.

Alternatively, the gas diffusion layer is an elastic graphene porous membrane, and thus has a uniform porous thin-layer structure and is excellent in stretchability, electrical conductivity, chemical stability, and thermal stability. In addition, graphene is sp²The hybridized and connected carbon atoms are tightly packed into a material with a single-layer two-dimensional honeycomb lattice structure, and the material has more excellent electrical and mechanical properties.

Alternatively, the gas diffusion layer is an elastic carbon fiber porous membrane, and thus has a uniform porous thin-layer structure and is excellent in stretchability, electrical conductivity, chemical stability, and thermal stability. In addition, the carbon fiber is high-strength and high-modulus fiber with carbon content of more than 90%, and has the advantages of high temperature resistance, friction resistance, electric conduction, corrosion resistance and the like.

Or the gas diffusion layer is an elastic carbon felt, and the carbon felt is a felt made of carbon fibers, has enough mechanical strength, and can support the catalyst layer and stabilize the electrode structure. In addition, the gas diffusion layer has a uniform porous thin-layer structure and is excellent in stretchability, electrical conductivity, chemical stability, and thermal stability.

Alternatively, the gas diffusion layer is made of elastic carbon paper, and thus has a uniform porous thin-layer structure and is excellent in stretchability, electrical conductivity, chemical stability, and thermal stability.

In the above technical solution, the method further comprises: and the proton exchange membrane is arranged on one side of the catalyst layer, which is far away from the gas diffusion layer.

In the technical scheme, the fuel cell membrane electrode also comprises a proton exchange membrane. In particular, the proton exchange membrane is arranged on the side of the catalyst layer facing away from the gas diffusion layer. The Proton Exchange Membrane (PEM) provides a channel for the migration and transportation of protons, and has the functions of blocking and conducting protons. The proton passes through the proton exchange membrane from the anode to the cathode, and forms a loop with the electron transfer of an external circuit to provide current for the outside, so the performance of the proton exchange membrane plays a very important role in the performance of the membrane electrode of the fuel cell, and the service life of the cell is directly influenced. The material of the proton exchange membrane meets the following conditions: good proton conductivity; the electroosmosis of water molecules in the membrane is small; the permeability of the gas in the membrane is as small as possible; the electrochemical stability is good; the dry-wet conversion performance is good; has certain mechanical strength; the processability is good; the cost is low. The proton exchange membrane may be of the perfluorosulfonic acid type, a recast membrane, a non-fluoropolymer, or the like. The catalyst layer is disposed on at least one side of the proton exchange membrane. The catalyst layer serves as a catalyst and platinum or other materials may be used.

In the technical scheme, a hydrophobic layer is arranged on one side of the gas diffusion layer close to the catalyst layer.

In the technical scheme, the gas diffusion layer is provided with the hydrophobic layer on one side close to the catalyst layer, the hydrophobic layer is provided with the micropores, and the gas diffusion layer can provide a gas channel, an electronic channel and a drainage channel for electrode reaction.

In the above technical solution, the thickness of the hydrophobic layer is 50nm to 5000 nm.

In the technical scheme, the thickness of the hydrophobic layer is controlled to be 50nm to 5000nm, so that on one hand, the possibility that water molecules pass through places except micropores can be reduced; on the other hand, the manufacturing cost is favorably reduced, and the waste of materials is effectively avoided.

In the above technical solution, the hydrophobic layer is made of polytetrafluoroethylene and carbon nanoparticles.

In the technical scheme, the hydrophobic layer adopts polytetrafluoroethylene and carbon nano particles, the polytetrafluoroethylene is a high molecular polymer prepared by polymerizing tetrafluoroethylene serving as a monomer, the carbon nano particles are seamless and hollow tubes formed by rolling graphite sheets consisting of a layer of carbon atoms at a certain angle, and the polytetrafluoroethylene and the carbon nano particles are both good hydrophobic materials.

The second aspect of the present invention provides a membrane electrode preparation method for a fuel cell membrane electrode in any one of the above embodiments, including: preparing a proton exchange membrane, a catalyst layer and a polar plate; connecting the side wall of the catalyst layer with the side wall of the proton exchange membrane, and positioning the polar plate at one side of the catalyst layer, which is far away from the proton exchange membrane; selecting a gas diffusion layer with proper size and thickness according to the structure of the catalyst layer; coating a hydrophobic layer on one side of the gas diffusion layer; and the gas diffusion layer is arranged between the catalyst layer and the polar plate, and the hydrophobic layer is connected with the catalyst layer.

According to the embodiment of the membrane electrode preparation method of the invention, the membrane electrode preparation method is used for preparing a fuel cell membrane electrode, and the fuel cell membrane electrode, namely a membrane electrode assembly, also called a membrane electrode, can be understood as an electrode which is provided with a membrane combination on the structure and is a key core component for power generation of a fuel cell. The preparation method of the membrane electrode comprises the following specific steps:

the first step is as follows: a proton exchange membrane, a catalyst layer and a plate are prepared. The Proton Exchange Membrane (PEM) provides a channel for the migration and transportation of protons, and has the functions of blocking and conducting protons. The proton passes through the proton exchange membrane from the anode to the cathode, and forms a loop with the electron transfer of an external circuit to provide current for the outside, so the performance of the proton exchange membrane plays a very important role in the performance of the membrane electrode of the fuel cell, and the service life of the cell is directly influenced. The material of the proton exchange membrane meets the following conditions: good proton conductivity; the electroosmosis of water molecules in the membrane is small; the permeability of the gas in the membrane is as small as possible; the electrochemical stability is good; the dry-wet conversion performance is good; has certain mechanical strength; the processability is good; the cost is low. The proton exchange membrane may be of the perfluorosulfonic acid type, a recast membrane, a non-fluoropolymer, or the like. The catalyst layer serves as a catalyst and platinum or other materials may be used. The number of the catalyst layers is two, and the two catalyst layers are divided into an anode catalyst layer and a cathode catalyst layer. The number of the polar plates is also two, and the two polar plates are divided into an anode polar plate and a cathode polar plate;

the second step is that: connecting the side wall of the catalyst layer with the side wall of the proton exchange membrane, and positioning the polar plate at one side of the catalyst layer, which is far away from the proton exchange membrane;

the third step: the gas diffusion layer of appropriate size and thickness is selected according to the structure of the catalyst layer. The gas diffusion layer plays a role in supporting the catalyst layer and stabilizing the electrode structure in the fuel cell membrane electrode, and can also provide a gas channel, an electronic channel and a drainage channel for electrode reaction. The material of the gas diffusion layer satisfies the following conditions: uniform porous structure and good air permeability; the resistivity is low, and the electron conductivity is strong; the structure is compact and the surface is smooth, so that the contact resistance is reduced, and the conductivity is improved; has certain mechanical strength; proper hydrophilic and hydrophobic balance; has chemical stability and thermal stability; the manufacturing cost is low, and the cost performance is high;

the fourth step: a hydrophobic layer is applied to one side of the gas diffusion layer. The gas diffusion layer is provided with the hydrophobic layer on one side close to the catalyst layer, and the hydrophobic layer is provided with the micropores, so that the gas diffusion layer can provide a gas channel, an electronic channel and a drainage channel for electrode reaction;

the fifth step: and the gas diffusion layer is arranged between the catalyst layer and the polar plate, and the hydrophobic layer is connected with the catalyst layer. The number of gas diffusion layers is also two, one gas diffusion layer being located between the anode plate and the anode catalyst layer, and the other gas diffusion layer being located between the cathode plate and the cathode catalyst layer. The hydrogen gas reaches the anode through a gas flow field on the anode plate, through a gas diffusion layer, and to an anode catalyst layer. The hydrogen gas is adsorbed on the catalyst layer and is decomposed into two hydrogen ions, namely protons H under the action of the catalyst platinum⁺And two electrons are released, this process is called the anodic oxidation process of hydrogen, and the reactions taking place at the anode are: h₂＝2H⁺+2 e. At the other end of the cell, oxygen or air passes throughThe gas flow field on the cathode plate reaches the cathode, and reaches the cathode catalyst layer through the diffusion layer on the electrode, oxygen is adsorbed on the cathode catalyst layer, meanwhile, hydrogen ions pass through the electrolyte to reach the cathode, and electrons also reach the cathode through an external circuit. Under the action of the cathode catalyst, oxygen, hydrogen ions and electrons react to generate water, and the process is called as the cathode reduction process of oxygen. The reactions occurring at the anode were: 1/2O₂+2H⁺+2e＝H₂And O. The overall chemical reaction formula is: h₂+1/2O₂＝H₂And O, meanwhile, the electrons form current under the connection of an external circuit, electric energy can be output to a load through proper connection, and generated water is discharged along with reaction tail gas.

A third aspect of the present invention provides a fuel cell system comprising: a housing; the fuel cell membrane electrode in any of the above embodiments is disposed in a housing.

According to an embodiment of the membrane electrode preparation method of the present invention, a fuel cell system includes a housing and a fuel cell membrane electrode, the fuel cell membrane electrode being provided in the housing. The fuel cell converts the Gibbs free energy in the chemical energy of the fuel into electric energy through electrochemical reaction, and is not limited by Carnot cycle effect, so the efficiency is higher, and the fuel cell uses the fuel and oxygen as raw materials, has no mechanical transmission part, discharges extremely little harmful gas and has long service life. A fuel cell membrane electrode, i.e. a membrane electrode assembly, also called membrane electrode, can be understood as an electrode equipped with a membrane assembly in its structure, which is a key core component of fuel cell power generation.

A fourth aspect of the invention provides a vehicle comprising: a frame body; the fuel cell membrane electrode in any one of the above embodiments is arranged on the frame body; or the fuel cell system in the above embodiment, is provided in the frame body.

According to an embodiment of a vehicle of the present invention, the vehicle includes a frame body and a fuel cell membrane electrode provided on the frame body. Alternatively, the vehicle includes a frame and a fuel cell system provided on the frame. The frame body is understood to be a chassis of a vehicle, and the fuel cell membrane electrode or the fuel cell system can provide energy for the vehicle.

Additional aspects and advantages of embodiments of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.

Drawings

Fig. 1 shows a schematic view of a gas diffusion layer in the related art;

FIG. 2 shows a first schematic view of a fuel cell membrane electrode assembly according to one embodiment of the invention;

FIG. 3 shows a second schematic view of a fuel cell membrane electrode assembly according to an embodiment of the invention;

FIG. 4 shows a schematic flow diagram of a membrane electrode fabrication method according to one embodiment of the present invention;

FIG. 5 shows a schematic diagram of a fuel cell system according to an embodiment of the invention;

FIG. 6 shows a first schematic view of a vehicle according to an embodiment of the invention;

FIG. 7 shows a second schematic view of a vehicle according to an embodiment of the invention.

Wherein, the corresponding relation between the reference numbers and the part names in fig. 1 is as follows:

130': a gas diffusion layer.

The correspondence between the reference numerals and the names of the components in fig. 2 to 7 is:

100: a fuel cell membrane electrode; 110: a proton exchange membrane; 120: a catalyst layer; 130: a gas diffusion layer; 140: a polar plate; 150: a hydrophobic layer; 300: a fuel cell system; 310: a housing; 400: a vehicle; 410: a shelf body.

Detailed Description

In order that the above objects, features and advantages of the embodiments of the present invention can be more clearly understood, embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and detailed description. It should be noted that the embodiments and features of the embodiments of the present application may be combined with each other without conflict.

In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application, however, embodiments of the present invention may be practiced in other ways than those described herein, and therefore the scope of the present application is not limited to the specific embodiments disclosed below.

A fuel cell membrane electrode 100, a membrane electrode preparation method, a fuel cell system 300, and a vehicle 400 provided according to some embodiments of the present invention are described below with reference to fig. 1 to 7.

Example one

A fuel cell is a chemical device that directly converts chemical energy of fuel into electrical energy, and is also called an electrochemical generator. Fuel cells are the fourth power generation technology following hydroelectric, thermal, and nuclear power generation. The fuel cell converts the Gibbs free energy in the chemical energy of the fuel into electric energy through electrochemical reaction, and is not limited by Carnot cycle effect, so the efficiency is higher, and the fuel cell uses the fuel and oxygen as raw materials, has no mechanical transmission part, discharges extremely little harmful gas and has long service life. The fuel cell membrane electrode 100, i.e., a membrane electrode assembly, also called a membrane electrode, can be understood as an electrode equipped with a membrane assembly in its structure, which is a key core component of fuel cell power generation.

As shown in fig. 2 and 3, a fuel cell membrane electrode 100 according to an embodiment of the present invention includes a catalyst layer 120, a gas diffusion layer 130, and a plate 140. The gas diffusion layer 130 is disposed on at least one side of the catalyst layer 120, and the plate 140 is disposed on a side of the gas diffusion layer 130 facing away from the catalyst layer 120. The gas diffusion layer 130 plays a role of not only supporting the catalyst layer 120 and stabilizing the electrode structure in the fuel cell membrane electrode 100, but also providing a gas channel, an electron channel, and a water discharge channel for the electrode reaction. The material of the gas diffusion layer 130 satisfies the following conditions: uniform porous structure and good air permeability; the resistivity is low, and the electron conductivity is strong; the structure is compact and the surface is smooth, so that the contact resistance is reduced, and the conductivity is improved; has certain mechanical strength; proper hydrophilic and hydrophobic balance; has chemical stability and thermal stability; the manufacturing cost is low, and the cost performance is high.

General conditionsIn this case, the number of the catalyst layers 120 is two, and the two catalyst layers 120 are respectively located on two sides of the proton exchange membrane 110. The two catalyst layers 120 are divided into an anode catalyst layer 120 and a cathode catalyst layer 120. In addition, the number of the plates 140 and the gas diffusion layers 130 is also two, and the two plates 140 are divided into an anode plate 140 and a cathode plate 140, wherein one gas diffusion layer 130 is located between the anode plate 140 and the anode catalyst layer 120, and the other gas diffusion layer 130 is located between the cathode plate 140 and the cathode catalyst layer 120. The hydrogen gas reaches the anode through the gas flow field on the anode plate 140, and reaches the anode catalyst layer 120 through the gas diffusion layer 130. The hydrogen gas is adsorbed on the catalyst layer 120 and is decomposed into two hydrogen ions, i.e., protons H, by the action of the catalyst platinum⁺And two electrons are released, this process is called the anodic oxidation process of hydrogen, and the reactions taking place at the anode are: h₂＝2H⁺+2 e. At the other end of the cell, oxygen or air passes through the gas flow field on the cathode plate 140 to the cathode, passes through the diffusion layer on the electrode to the cathode catalyst layer 120, oxygen is adsorbed on the cathode catalyst layer 120, and at the same time, hydrogen ions pass through the electrolyte to the cathode, and electrons also pass through an external circuit to the cathode. Under the action of the cathode catalyst, oxygen, hydrogen ions and electrons react to generate water, and the process is called as the cathode reduction process of oxygen. The reactions occurring at the anode were: 1/2O₂+2H⁺+2e＝H₂And O. The overall chemical reaction formula is: h₂+1/2O₂＝H₂And O, meanwhile, the electrons form current under the connection of an external circuit, electric energy can be output to a load through proper connection, and generated water is discharged along with reaction tail gas.

Furthermore, the material of the gas diffusion layer 130 is an elastic material, on one hand, the gas diffusion layer 130 is a porous structure, has better air permeability, and can provide a gas channel, an electronic channel and a drainage channel for electrode reaction; on the other hand, the gas diffusion layer 130 is made of an elastic material, so that the expansion and contraction performance is better; further, the gas diffusion layer 130 is made of a carbon material, ensures material properties thereof, has sufficient mechanical strength, and functions to support the catalyst layer 120 and stabilize the electrode structure.

During operation of the fuel cell membrane electrode 100, the proton exchange membrane 110 expands and contracts with changes in humidity and temperature. Due to the expansion and contraction of the pem 110 and the difference in expansion coefficients, combined with the restriction in the position of the two plates 140, the in-plane compression and extension of the damp heat will generate pressure. As shown in fig. 1, the conventional gas diffusion layer 130' is brittle and easily separated from the plate 140 or the catalyst layer 120 by internal stress such as compressive stress, freezing, thawing or swelling, thereby causing mechanical degradation, and particularly after several thermal-humidity cycles, the thermal-humidity stress affects the life and performance of the fuel cell.

In the technical scheme defined by the application, the gas diffusion layer 130 is made of an elastic material, so that the air permeability and the telescopic performance are better, and when the internal stress of the stack is enhanced, the gas diffusion layer 130 is effectively contracted; when the stress is weakened, the gas diffusion layer 130 is relaxed, so that the stress inside the stack can be in a proper range, the possibility of separation between the gas diffusion layer 130 and the catalyst layer 120 or between the gas diffusion layer 130 and the polar plate 140 is greatly reduced, the stability of the stack under different operating environments and working conditions is ensured, and the stability and the durability of the fuel cell are improved.

Further, the plate 140, the gas diffusion layer 130, and the catalyst layer 120 are an integrated structure. The polar plate 140, the gas diffusion layer 130 and the catalyst layer 120 are produced by chemical vapor deposition, on one hand, the connection strength between the polar plate 140 and the gas diffusion layer 130 and between the gas diffusion layer 130 and the catalyst layer 120 are favorably improved, and the gaps between the polar plate 140 and the gas diffusion layer 130 and between the gas diffusion layer 130 and the catalyst layer 120 are reduced as much as possible, so that the possibility of separation between the catalyst layer 120 and the proton exchange membrane 110, between the catalyst layer 120 and the gas diffusion layer 130 and between the gas diffusion layer 130 and the polar plate 140 is greatly reduced, and when the fuel cell operates under different working conditions, the internal stress can be always kept in a stable range, thereby ensuring that the stack is kept stable under different operating environments and working conditions, and further improving the stability and the durability of the fuel cell; on the other hand, the number of parts is reduced, and the assembly efficiency of workers can be improved. Chemical vapor deposition is a chemical technology, which is a method for generating a film by performing a chemical reaction on the surface of a substrate by using one or more gas-phase compounds or simple substances containing film elements.

Example two

The fuel cell membrane electrode 100 also includes a proton exchange membrane 110. In particular, the proton exchange membrane 110(PEM) provides a passage for migration and transport of protons, and has a function of not only blocking but also conducting protons. The proton passes through the proton exchange membrane 110 from the anode to the cathode, and forms a loop with the electron transfer of an external circuit to provide current to the outside, so the performance of the proton exchange membrane 110 plays an important role in the performance of the fuel cell membrane electrode 100, and directly affects the service life of the cell. The material of the proton exchange membrane 110 satisfies the following conditions: good proton conductivity; the electroosmosis of water molecules in the membrane is small; the permeability of the gas in the membrane is as small as possible; the electrochemical stability is good; the dry-wet conversion performance is good; has certain mechanical strength; the processability is good; the cost is low. The proton exchange membrane 110 may be of the perfluorosulfonic acid type, a recast membrane, a non-fluoropolymer, or the like. The catalyst layer 120 is disposed on at least one side of the proton exchange membrane 110. The catalyst layer 120 serves as a catalyst and platinum or other materials may be used.

EXAMPLE III

The gas diffusion layer 130 is an elastic carbon nanotube porous membrane. By providing the gas diffusion layer 130 as an elastic carbon nanotube porous membrane, the gas diffusion layer 130 has a uniform porous thin-layer structure and is excellent in stretchability, electrical conductivity, chemical stability, and thermal stability. In addition, the carbon nano tube is made of nano material and has the advantages of light weight and the like.

In another embodiment, the gas diffusion layer 130 is an elastic graphene porous membrane. By providing the gas diffusion layer 130 as an elastic graphene porous membrane, the gas diffusion layer 130 has a uniform porous thin-layer structure and is excellent in stretchability, electrical conductivity, chemical stability, and thermal stability. In addition, graphene is sp²Hybrid linked carbon atomThe material with a single-layer two-dimensional honeycomb lattice structure is formed by closely packing the particles, and has more excellent electrical and mechanical properties.

In another embodiment, gas diffusion layer 130 is an elastic carbon fiber porous membrane. By providing the gas diffusion layer 130 as an elastic carbon fiber porous membrane, the gas diffusion layer 130 has a uniform porous thin-layer structure and is excellent in stretchability, electrical conductivity, chemical stability, and thermal stability. In addition, the carbon fiber is high-strength and high-modulus fiber with carbon content of more than 90%, and has the advantages of high temperature resistance, friction resistance, electric conduction, corrosion resistance and the like.

In another embodiment, gas diffusion layer 130 is an elastic carbon felt. By providing the gas diffusion layer 130 as an elastic carbon felt, which is a felt made of carbon fibers, it has sufficient mechanical strength to support the catalyst layer 120 and stabilize the electrode structure. The gas diffusion layer 130 has a uniform porous thin-layer structure and is excellent in stretchability, electrical conductivity, chemical stability, and thermal stability.

In another embodiment, the gas diffusion layer 130 is an elastic carbon paper. By providing the gas diffusion layer 130 as an elastic carbon paper, the gas diffusion layer 130 has a uniform porous thin-layer structure, and has excellent stretchability, electrical conductivity, chemical stability, and thermal stability.

Example four

As shown in fig. 3, a hydrophobic layer 150 is disposed on a side of the gas diffusion layer 130 close to the catalyst layer 120, and micropores are disposed on the hydrophobic layer 150, so that the gas diffusion layer 130 can provide a gas channel, an electron channel, and a water drainage channel for electrode reaction. Further, the thickness of the hydrophobic layer 150 is 50nm to 5000nm, and by controlling the thickness of the hydrophobic layer 150, on one hand, the possibility that water molecules pass through places other than micropores can be reduced; on the other hand, the manufacturing cost is favorably reduced, and the waste of materials is effectively avoided.

Further, the hydrophobic layer 150 is made of polytetrafluoroethylene and carbon nanoparticles, the polytetrafluoroethylene is a high molecular polymer prepared by polymerizing tetrafluoroethylene as a monomer, the carbon nanoparticles are seamless hollow tubes formed by rolling graphite sheets composed of a layer of carbon atoms at a certain angle, and the graphite sheets and the carbon nanoparticles are both good hydrophobic materials.

EXAMPLE five

As shown in fig. 4, the membrane electrode preparation method provided by an embodiment of the present invention is used for preparing a fuel cell membrane electrode, which is a membrane electrode assembly, also called a membrane electrode, and can be understood as an electrode equipped with a membrane assembly on its structure, and is a key core component for power generation of a fuel cell. The preparation method of the membrane electrode comprises the following specific steps:

step S502, a proton exchange membrane, a catalyst layer, and a polar plate are prepared. The Proton Exchange Membrane (PEM) provides a channel for the migration and transportation of protons, and has the functions of blocking and conducting protons. The proton passes through the proton exchange membrane from the anode to the cathode, and forms a loop with the electron transfer of an external circuit to provide current for the outside, so the performance of the proton exchange membrane plays a very important role in the performance of the membrane electrode of the fuel cell, and the service life of the cell is directly influenced. The material of the proton exchange membrane meets the following conditions: good proton conductivity; the electroosmosis of water molecules in the membrane is small; the permeability of the gas in the membrane is as small as possible; the electrochemical stability is good; the dry-wet conversion performance is good; has certain mechanical strength; the processability is good; the cost is low. The proton exchange membrane may be of the perfluorosulfonic acid type, a recast membrane, a non-fluoropolymer, or the like. The catalyst layer serves as a catalyst and platinum or other materials may be used. The number of the catalyst layers is two, and the two catalyst layers are divided into an anode catalyst layer and a cathode catalyst layer. The number of the polar plates is also two, and the two polar plates are divided into an anode polar plate and a cathode polar plate;

step S504, connecting the side wall of the catalyst layer with the side wall of the proton exchange membrane, and positioning the polar plate at one side of the catalyst layer, which is far away from the proton exchange membrane;

step S506, a gas diffusion layer with a suitable size and thickness is selected according to the structure of the catalyst layer. The gas diffusion layer plays a role in supporting the catalyst layer and stabilizing the electrode structure in the fuel cell membrane electrode, and can also provide a gas channel, an electronic channel and a drainage channel for electrode reaction. The material of the gas diffusion layer satisfies the following conditions: uniform porous structure and good air permeability; the resistivity is low, and the electron conductivity is strong; the structure is compact and the surface is smooth, so that the contact resistance is reduced, and the conductivity is improved; has certain mechanical strength; proper hydrophilic and hydrophobic balance; has chemical stability and thermal stability; the manufacturing cost is low, and the cost performance is high;

step S508, a hydrophobic layer is coated on one side of the gas diffusion layer. The gas diffusion layer is provided with the hydrophobic layer on one side close to the catalyst layer, and the hydrophobic layer is provided with the micropores, so that the gas diffusion layer can provide a gas channel, an electronic channel and a drainage channel for electrode reaction;

step S510, a gas diffusion layer is disposed between the catalyst layer and the electrode plate, and the hydrophobic layer is connected to the catalyst layer. The number of gas diffusion layers is also two, one gas diffusion layer being located between the anode plate and the anode catalyst layer, and the other gas diffusion layer being located between the cathode plate and the cathode catalyst layer. The hydrogen gas reaches the anode through a gas flow field on the anode plate, through a gas diffusion layer, and to an anode catalyst layer. The hydrogen gas is adsorbed on the catalyst layer and is decomposed into two hydrogen ions, namely protons H under the action of the catalyst platinum⁺And two electrons are released, this process is called the anodic oxidation process of hydrogen, and the reactions taking place at the anode are: h₂＝2H⁺+2 e. At the other end of the cell, oxygen or air passes through the gas flow field on the cathode plate to the cathode, through the diffusion layer on the electrode to the cathode catalyst layer where it is adsorbed, while hydrogen ions pass through the electrolyte to the cathode, and electrons also pass through an external circuit to the cathode. Under the action of the cathode catalyst, oxygen, hydrogen ions and electrons react to generate water, and the process is called as the cathode reduction process of oxygen. The reactions occurring at the anode were: 1/2O₂+2H⁺+2e＝H₂And O. The overall chemical reaction formula is: h₂+1/2O₂＝H₂And O, meanwhile, the electrons form current under the connection of an external circuit, electric energy can be output to a load through proper connection, and generated water is discharged along with reaction tail gas.

EXAMPLE six

As shown in fig. 5, a fuel cell system 300 according to an embodiment of the present invention includes a housing 310 and the fuel cell membrane electrode 100 of any of the above embodiments, wherein the fuel cell membrane electrode 100 is disposed in the housing 310. The fuel cell converts the Gibbs free energy in the chemical energy of the fuel into electric energy through electrochemical reaction, and is not limited by Carnot cycle effect, so the efficiency is higher, and the fuel cell uses the fuel and oxygen as raw materials, has no mechanical transmission part, discharges extremely little harmful gas and has long service life. The fuel cell membrane electrode 100, i.e., a membrane electrode assembly, also called a membrane electrode, can be understood as an electrode equipped with a membrane assembly in its structure, which is a key core component of fuel cell power generation.

EXAMPLE seven

As shown in fig. 6, a vehicle 400 according to an embodiment of the present invention includes a frame 410 and the fuel cell membrane electrode 100 of any of the above embodiments, where the fuel cell membrane electrode 100 is disposed on the frame 410. Alternatively, as shown in fig. 7, the vehicle 400 includes a frame 410 and the fuel cell system 300 in the above embodiment, and the fuel cell system 300 is provided on the frame 410. The frame 410 may be understood as a chassis of the vehicle 400, and the fuel cell membrane electrode 100 or the fuel cell system 300 may be capable of supplying power to the vehicle 400.

According to the embodiments of the fuel cell membrane electrode, the membrane electrode preparation method, the fuel cell system and the vehicle, the gas diffusion layer is made of the porous elastic carbon material, so that the air permeability and the telescopic performance are better, and when the internal stress of a stack is enhanced, the gas diffusion layer is effectively contracted; when the stress is weakened, the gas diffusion layer relaxes, so that the stress in the electric pile can be in a proper range, the possibility of separation between the gas diffusion layer and the catalyst layer or between the gas diffusion layer and the polar plate is greatly reduced, the electric pile is ensured to be stable under different operating environments and working conditions, and the stability and the durability of the fuel cell are improved. In addition, the polar plate, the gas diffusion layer and the catalyst layer are of an integrated structure, so that gaps between the polar plate and the gas diffusion layer and gaps between the gas diffusion layer and the catalyst layer can be reduced, and the stability and the durability of the fuel cell can be further improved.

In the present invention, the terms "first", "second", and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance; the term "plurality" means two or more unless expressly limited otherwise. The terms "mounted," "connected," "fixed," and the like are to be construed broadly, and for example, "connected" may be a fixed connection, a removable connection, or an integral connection; "coupled" may be direct or indirect through an intermediary. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

In the description of the present invention, it is to be understood that the terms "upper", "lower", "left", "right", "front", "rear", and the like indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience of description and simplification of description, but do not indicate or imply that the referred device or unit must have a specific direction, be constructed in a specific orientation, and be operated, and thus, should not be construed as limiting the present invention.

In the description herein, the description of the terms "one embodiment," "some embodiments," "specific embodiments," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

The above is only a preferred embodiment of the present invention, and is not intended to limit the present invention, and various modifications and changes will occur to those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A fuel cell membrane electrode assembly comprising:

a catalyst layer (120);

a gas diffusion layer (130) provided on at least one side of the catalyst layer (120);

a plate (140) arranged on the side of the gas diffusion layer (130) facing away from the catalyst layer (120),

the material of the gas diffusion layer (130) is an elastic material, and the polar plate (140), the gas diffusion layer (130) and the catalyst layer (120) are produced into an integrated structure in a chemical vapor deposition mode.

2. The fuel cell membrane electrode assembly according to claim 1, wherein the gas diffusion layer (130) is any one of an elastic carbon nanotube porous membrane, an elastic graphene porous membrane, an elastic carbon fiber porous membrane, an elastic carbon felt, or an elastic carbon paper.

3. The fuel cell membrane electrode assembly according to claim 1 further comprising:

a proton exchange membrane (110) provided on a side of the catalyst layer (120) facing away from the gas diffusion layer (130).

4. The fuel cell membrane electrode according to claim 1, characterised in that the side of the gas diffusion layer (130) close to the catalyst layer (120) is provided with a hydrophobic layer (150).

5. The fuel cell membrane electrode assembly according to claim 4, wherein the thickness of the hydrophobic layer (150) is 50nm to 5000 nm.

6. The fuel cell membrane electrode assembly according to claim 4 or 5, wherein the material of the hydrophobic layer (150) comprises polytetrafluoroethylene and carbon nanoparticles.

7. A membrane electrode preparation method for a fuel cell membrane electrode according to any one of claims 1 to 6, comprising:

preparing a proton exchange membrane, a catalyst layer and a polar plate;

connecting the side wall of the catalyst layer with the side wall of the proton exchange membrane, and positioning the polar plate at one side of the catalyst layer, which is far away from the proton exchange membrane;

selecting a gas diffusion layer with proper size and thickness according to the structure of the catalyst layer;

coating a hydrophobic layer on one side of the gas diffusion layer;

and the gas diffusion layer is arranged between the catalyst layer and the polar plate, and the hydrophobic layer is connected with the catalyst layer.

8. A fuel cell system, characterized by comprising:

a housing (310);

the fuel cell membrane electrode (100) according to any one of claims 1 to 6, provided within the housing (310).

9. A vehicle, characterized by comprising:

a frame body (410);

the fuel cell membrane electrode (100) according to any one of claims 1 to 6, provided to the frame body (410); or

The fuel cell system (300) of claim 8, being disposed on the frame (410).