JP2025112401A - Catalyst layer for membrane electrode assembly, membrane electrode assembly, and method for manufacturing catalyst layer - Google Patents

Abstract

The present invention aims to improve the efficiency of electrochemical reactions in a catalyst layer.
[Solution] The catalyst layer 109 of the present disclosure comprises a carrier particle 11, a catalyst particle 12 supported on the carrier particle 11, conductive fibers 13 arranged in contact with the carrier particle 11, a first resin layer 15a containing a first resin material having proton conductivity and covering at least a portion of the surface of the conductive fibers 13, and a second resin layer 15b containing a second resin material having lower hydrophilicity than the first resin material and covering at least a portion of the outer surface of the first resin layer 15a.
[Selected Figure] Figure 3

Description

This disclosure relates to a catalyst layer for a membrane electrode assembly, a membrane electrode assembly, and a method for manufacturing a catalyst layer.

Electrochemical devices such as fuel cells use a membrane electrode assembly that has an anode, electrolyte membrane, and cathode. The anode and cathode of the membrane electrode assembly each have a catalyst layer. The catalyst layer uses carbon particles carrying catalyst particles as an electrode catalyst. In the catalyst layer, the electrode catalyst is covered with an ion-conductive polymer electrolyte.

Patent Document 1 describes an electrode catalyst layer for a polymer electrolyte fuel cell. The electrode catalyst layer includes a catalyst, carbon particles, a polymer electrolyte, and a fibrous material.

Japanese Patent Application Laid-Open No. 2022-162113 JP 2018-181838 A

In conventional technology, it is desirable to improve the efficiency of electrochemical reactions by achieving both proton conductivity and drainage in the catalyst layer.

The present disclosure provides:
Carrier particles;
catalyst particles supported on the support particles;
Conductive fibers arranged in contact with the carrier particles;
a first resin layer containing a first resin material having proton conductivity and covering at least a part of the surface of the conductive fiber;
a second resin layer including a second resin material having a lower hydrophilicity than the first resin material and covering at least a portion of an outer surface of the first resin layer;
The present invention provides a catalyst layer for a membrane electrode assembly, comprising:

In another aspect, the present disclosure provides a method for manufacturing a semiconductor device comprising:
A catalyst layer for a membrane electrode assembly, comprising:
Carrier particles;
catalyst particles supported on the support particles;
Conductive fibers arranged in contact with the carrier particles;
a resin material attached to the conductive fiber;
Equipped with
the resin material includes a first resin material having proton conductivity and a second resin material having lower hydrophilicity than the first resin material;
the proton conduction resistance of the catalyst layer measured when AC impedance of the membrane electrode assembly including the catalyst layer is measured under conditions of a temperature of 50°C and a relative humidity of 100% is 250 mΩ/ ^cm2 or less;
A catalyst layer for a membrane electrode assembly is provided.

In yet another aspect, the present disclosure provides a method for manufacturing a semiconductor device comprising:
preparing a preliminary solution by mixing carrier particles carrying catalyst particles, conductive fibers, a first resin material having proton conductivity, and a solvent;
preparing a catalyst ink by dispersing a second resin material having a lower hydrophilicity than the first resin material in the preliminary solution;
applying the catalyst ink to a substrate to form a catalyst layer;
The present invention provides a method for producing a catalyst layer for a membrane electrode assembly, comprising:

The technology disclosed herein can improve the efficiency of electrochemical reactions by achieving both proton conductivity and drainage in the catalyst layer.

1 is a schematic cross-sectional view of a fuel cell according to a first embodiment; Partially enlarged cross-sectional view of the cathode catalyst layer Partially enlarged view of Figure 2 Process diagram showing the manufacturing method of the cathode catalyst layer FIG. 1 is a diagram illustrating a method for calculating proton conduction resistance from a complex impedance plot obtained by AC impedance measurement.

(Findings that formed the basis of this disclosure)
At the time the present inventors conceived the present disclosure, catalyst layers containing fibrous materials such as carbon nanofibers were known (see Patent Document 1). It was believed that fibrous materials promote pore formation and improve drainage and gas diffusion. However, conventional catalyst layers use polymer electrolytes containing sulfonic acid groups, which are characterized by high hydrophilicity. Therefore, water generated during operation and water generated from humidified gases tend to accumulate in the pores of the catalyst layer. Water accumulation in the pores inhibits gas diffusion, resulting in a decrease in the performance of the electrochemical device. This phenomenon is often referred to as flooding.

In light of this situation, the inventors investigated the configuration of a catalyst layer that could achieve both proton conductivity and drainage properties. As a result of their intensive investigations, they have completed the catalyst layer disclosed herein.

Embodiments will be described in detail below with reference to the drawings. However, more detailed explanations than necessary may be omitted. For example, detailed explanations of matters that are already well known or redundant explanations of substantially identical configurations may be omitted.

The accompanying drawings and the following description are provided to enable those skilled in the art to fully understand the present disclosure, and are not intended to limit the subject matter described in the claims.

(Embodiment 1)
Hereinafter, the first embodiment will be described with reference to FIGS. 1 to 4. FIG.

[1-1. Configuration]
1 is a schematic cross-sectional view of a fuel cell 101 according to Embodiment 1. The fuel cell 101 includes a membrane electrode assembly 113, an anode separator 106, and a cathode separator 111. The membrane electrode assembly 113 is disposed between the anode separator 106 and the cathode separator 111. The fuel cell 101 is, for example, a polymer electrolyte fuel cell.

The membrane electrode assembly 113 can also be used in other electrochemical devices, such as a hydrogen purification device that purifies hydrogen.

The membrane electrode assembly 113 has an anode 103, an electrolyte membrane 102, and a cathode 108. The anode 103 is bonded to one surface of the electrolyte membrane 102. The cathode 108 is bonded to the other surface of the electrolyte membrane 102.

The electrolyte membrane 102 is disposed between the anode 103 and the cathode 108. The electrolyte membrane 102 is made of a polymer material with proton conductivity. For example, the electrolyte membrane 102 is a membrane made of a perfluorocarbon sulfonic acid-based polymer material with sulfonic acid groups, or a hydrocarbon-based polymer material.

The anode 103 has an anode catalyst layer 104 and an anode gas diffusion layer 105. The anode catalyst layer 104 is disposed between the electrolyte membrane 102 and the anode gas diffusion layer 105. The cathode 108 has a cathode catalyst layer 109 and a cathode gas diffusion layer 110. The cathode catalyst layer 109 is disposed between the electrolyte membrane 102 and the cathode gas diffusion layer 110.

The anode catalyst layer 104 functions to promote the electrochemical reaction that dissociates hydrogen molecules into protons. The anode catalyst layer 104 includes an electrode catalyst and a polymer electrolyte. The anode catalyst layer 104 may also include carbon particles carrying catalyst particles and a polymer electrolyte.

The anode gas diffusion layer 105 has the function of supplying hydrogen-containing gas to the anode catalyst layer 104 and the function of receiving electrons from the anode catalyst layer 104. The anode gas diffusion layer 105 is made of a gas-permeable and electrically conductive material. The anode gas diffusion layer 105 has, as its main material, for example, a conductive porous body. Examples of porous bodies include carbon fiber aggregates such as carbon paper.

The cathode catalyst layer 109 functions to promote the electrochemical reaction that produces water from protons and oxygen. The detailed structure of the cathode catalyst layer 109 will be described later.

The cathode gas diffusion layer 110 has the function of supplying oxidant gas to the cathode catalyst layer 109 and the function of transferring electrons to the cathode catalyst layer 109. The cathode gas diffusion layer 110 is made of a gas-permeable and electrically conductive material. The cathode gas diffusion layer 110 primarily contains, for example, an electrically conductive porous body. Examples of the porous body include a carbon fiber aggregate such as carbon paper.

The anode separator 106 is provided with an anode gas flow path 107, which is a flow path for anode gas. The cathode separator 111 is provided with a cathode gas flow path 112, which is a flow path for cathode gas. The anode separator 106 and the cathode separator 111 are each made of a conductive material such as carbon or metal. To prevent corrosion, they may be provided with a corrosion-resistant coating such as resin or plating.

Figure 2 is a partially enlarged cross-sectional view of the cathode catalyst layer 109. The cathode catalyst layer 109 comprises an electrode catalyst 10, conductive fibers 13, and a resin material 15. The electrode catalyst 10, conductive fibers 13, and resin material 15 are in contact with each other. Pores 14 exist between the electrode catalysts 10, between the electrode catalysts 10 and the conductive fibers 13, and/or between the conductive fibers 13. The resin material 15 is sometimes called an ionomer.

The electrode catalyst 10 has a particle shape. The particles of the electrode catalyst 10 include a support particle 11 and a plurality of catalyst particles 12. The plurality of catalyst particles 12 are supported on the support particle 11.

The support particles 11 are electrically conductive. The support particles 11 are, for example, solid or porous carbon particles. Examples of solid carbon particles include carbon black particles such as ketjen black and acetylene black. In the case of solid carbon particles, catalyst particles 12 are supported on their surfaces. Examples of porous carbon particles include mesoporous carbon particles. In the case of porous carbon particles, catalyst particles 12 are disposed inside the pores (mesopores). By disposing the catalyst particles 12 inside the pores of the mesoporous carbon particles, poisoning of the catalyst particles 12 by the resin material 15 can be suppressed.

When the carrier particles 11 are solid carbon particles, their average particle size is, for example, 20 nm to 40 nm. When the carrier particles 11 are mesoporous carbon particles, their average particle size is, for example, 0.6 μm to 2.0 μm.

The average particle size of the carrier particles 11 is the average value of the diameters of multiple (e.g., 20 or more) carrier particles 11. The diameter of the carrier particles 11 can be measured using a scanning electron microscope or a transmission electron microscope (SEM or TEM). In an SEM image or TEM image of the carrier particles 11, the area of the carrier particles 11 is determined by image processing. The diameter of a circle having an area equal to the determined area can be considered to be the diameter of the carrier particle 11.

The technology of the present disclosure is particularly effective when the support particles 11 include mesoporous carbon particles. Mesoporous carbon particles tend to have larger dimensions than solid carbon particles. Therefore, using mesoporous carbon particles as the support particles 11 tends to increase the thickness of the cathode catalyst layer 109. As the thickness of the cathode catalyst layer 109 increases, the gas diffusion properties of the cathode catalyst layer 109 decrease. The technology of the present disclosure can compensate for the decrease in gas diffusion properties caused by the use of mesoporous carbon particles.

The catalyst particles 12 may be particles containing a precious metal such as platinum or a platinum alloy. Examples of platinum alloys include alloys of platinum with at least one metal selected from the group consisting of cobalt, nickel, ruthenium, and palladium.

The catalyst particles 12 may be nanoparticles. The catalyst particles 12 have an average particle size of, for example, 1 nm or more and 30 nm or less.

The average particle size of the catalyst particles 12 is the average value of the diameters of multiple (e.g., 100 or more) catalyst particles 12. The diameter of the catalyst particles 12 can be measured using a transmission electron microscope. In a TEM image of the electrode catalyst 10, the area of the catalyst particles 12 is determined by image processing. The diameter of a circle having an area equal to the determined area can be considered to be the diameter of the catalyst particle 12.

The conductive fibers 13 promote the formation of pores 14, improving drainage and gas diffusion in the cathode catalyst layer 109. In the cathode catalyst layer 109, the conductive fibers 13 are arranged so as to be in contact with the support particles 11 of the electrode catalyst 10. The particles of the electrode catalyst 10 are connected to each other by the conductive fibers 13. This promotes electron conduction in the cathode catalyst layer 109. A resin material 15 is attached to the conductive fibers 13. The conductive fibers 13 with the resin material 15 attached promote proton conduction in the cathode catalyst layer 109.

The conductive fibers 13 are, for example, carbon fibers. Examples of carbon fibers include carbon nanotubes, carbon nanofibers, and vapor-grown carbon fibers.

The average length of the conductive fibers 13 is, for example, 2 μm or more and 10 μm or less. The average fiber diameter of the conductive fibers 13 is, for example, 0.15 nm or more and 0.30 nm or less.

The average length of the conductive fibers 13 can be measured, for example, by the following method. The cathode catalyst layer 109 is dispersed in a solvent such as a water-ethanol mixture to prepare a dispersion, and the dispersion is then thinly applied to a substrate such as a glass plate to form a coating film. After the coating film is dried, the coating film is observed in one or more fields of view using an SEM or TEM. The lengths of multiple conductive fibers 13 are measured from the SEM or TEM image. For example, the average value of the measurements of 20 or more longest fibers can be considered to be the average length of the conductive fibers 13. The average fiber diameter can also be determined in the same way. The average length of the conductive fibers 13 may also be measured by directly observing the cathode catalyst layer 109 using an electron microscope.

In this embodiment, the conductive fibers 13 may be made of a material that does not support catalyst particles 12. This configuration prevents the catalyst particles 12 from being poisoned by the resin material 15. However, catalyst particles 12 that have fallen off the electrode catalyst 10 may be attached to the conductive fibers 13. In other words, "the conductive fibers 13 do not support catalyst particles 12" means that no treatment has been performed to support the catalyst particles 12 on the conductive fibers 13.

The resin material 15 contains a proton-conductive electrolyte and connects the electrode catalysts 10 together in a proton-conductive state. The resin material 15 is attached to both the carrier particles 11 and the conductive fibers 13. Only a portion of the surface of the carrier particles 11 may be coated with the resin material 15, or the entire surface of the carrier particles 11 may be coated with the resin material 15. Only a portion of the surface of the conductive fibers 13 may be coated with the resin material 15, or the entire surface of the conductive fibers 13 may be coated with the resin material 15.

In this embodiment, the resin material 15 includes a first resin material having proton conductivity and a second resin material having lower hydrophilicity than the first resin material. When AC impedance measurement is performed on the membrane electrode assembly 113 including the cathode catalyst layer 109 under conditions of a temperature of 50°C and a relative humidity of 100%, the proton conduction resistance measured is 250 mΩ/ ^cm² or less. This configuration makes it possible to achieve both proton conductivity and drainage properties in the cathode catalyst layer 109. As a result, flooding can be suppressed, improving the efficiency of the electrochemical reaction in the cathode catalyst layer 109 and ultimately improving the efficiency of the fuel cell 101.

According to the findings of the present inventors, when cathode catalyst layers were prepared with various compositions, the proton conduction resistance capable of exhibiting the desired performance was 220 mΩ/cm ² or less. Therefore, it can be said that a fuel cell can exhibit the desired performance when the proton conduction resistance is 250 mΩ/cm ² or less.

The lower limit of the proton conduction resistance is not particularly limited, and the proton conduction resistance may be 100 mΩ/cm ² or more.

The proton conduction resistance is measured for the entire anode catalyst layer 104 and cathode catalyst layer 109. The proton conduction resistance can be measured by the following method. A fuel cell 101 is prepared, including a single membrane electrode assembly 113 to be measured. Hydrogen gas with a relative humidity of 100% is supplied to the anode 103 at an appropriate flow rate. Nitrogen gas with a relative humidity of 100% is supplied to the cathode 108 at an appropriate flow rate. The ambient temperature is adjusted so that the temperatures of the anode 103 and cathode 108 are 50°C. The flow rates of the hydrogen gas and nitrogen gas are adjusted so that variations in the moisture content and gas leakage rate within the membrane electrode assembly 113 are sufficiently suppressed. After stabilizing the atmosphere around the anode 103 and cathode 108, an impedance analyzer is connected to the power output terminals, and AC impedance measurements are performed. Measurements are performed, for example, at a set voltage of 0.2 V, an amplitude of 0.01 V, and a frequency range of 0.1 Hz to 10 kHz. This gives a complex impedance plot.

FIG. 5 is a diagram illustrating a method for calculating the proton conduction resistance from a complex impedance plot obtained by AC impedance measurement. In the complex impedance plot, a line A is drawn to extrapolate the linear portion on the high frequency side onto the real axis. The value at the intersection of line A and the real axis is regarded as the proton conduction resistance R _pem of the electrolyte membrane. Next, a line B is drawn to extrapolate the linear portion on the low frequency side onto the real axis. The value R on the real axis corresponding to the intersection C of line A and line B is identified. The difference (R - R _pem ) between the value R and the proton conduction resistance R _pem of the electrolyte membrane is calculated. The overall proton conduction resistance R _cl of the anode catalyst layer 104 and the cathode catalyst layer 109 can be calculated using the formula (R - R _pem ) = R _cl /3.

Figure 3 is a partially enlarged view of Figure 2. As shown in Figure 3, the resin material 15 forms multiple (two) layers 15a and 15b on the surface of the conductive fiber 13. The multiple layers 15a and 15b include a first resin layer 15a and a second resin layer 15b. The first resin layer 15a is a layer containing a first resin material with proton conductivity and covers at least a portion of the surface of the conductive fiber 13. The entire surface of the conductive fiber 13 may be covered by the first resin layer 15a. The second resin layer 15b is a layer containing a second resin material that has lower hydrophilicity than the first resin material contained in the first resin layer 15a. The second resin layer 15b covers at least a portion of the outer surface of the first resin layer 15a. The entire outer surface of the first resin layer 15a may be covered by the second resin layer 15b.

With the above-described configuration, the first resin layer 15a imparts proton conductivity to the conductive fibers 13, and the second resin layer 15b imparts drainage properties to the conductive fibers 13. This makes it possible to improve the drainage properties of the pores 14 while maintaining proton conductivity. In other words, it is possible to achieve both proton conductivity and drainage properties in the cathode catalyst layer 109. As a result, flooding can be suppressed, improving the efficiency of the electrochemical reaction in the cathode catalyst layer 109, and ultimately improving the efficiency of the fuel cell 101.

The first resin layer 15a may be a proton-conducting layer responsible for proton conduction. The first resin layer 15a may be a layer made of the first resin material. In other words, the first resin layer 15a may contain only the first resin material, excluding inevitable impurities.

The first resin material may contain a polymer electrolyte, or may be a polymer electrolyte itself. This configuration can impart high proton conductivity to the conductive fibers 13.

Examples of the first resin material include polymer materials having proton-conducting groups such as sulfonic acid groups, phosphate groups, and carboxy groups. Specific examples of the first resin material include perfluorocarbon sulfonic acid-based polymer materials and hydrocarbon-based polymer materials.

Examples of polymeric materials having sulfonic acid groups include polymeric materials represented by the following formula (1). In formula (1), m and x each independently represent a positive integer.

The second resin layer 15b may be a hydrophobic layer that improves the drainage properties of the pores 14. The second resin layer 15b may be a layer made of the second resin material. In other words, the second resin layer 15b may contain only the second resin material, excluding inevitable impurities.

The second resin material may contain a polymer material that does not have proton-conductive functional groups, or may be such a polymer material itself. This configuration allows the pores 14 to have high hydrophobicity, further improving the drainage properties of the cathode catalyst layer 109. Here, proton-conductive functional groups refer to sulfonic acid groups, phosphate groups, carboxy groups, amino groups, etc.

An example of the second resin material is a fluororesin. It is preferable that the fluororesin is a resin that does not have a proton-conducting functional group. Specifically, examples of the second resin material include polytetrafluoroethylene (PTFE) and perfluoroalkoxyalkane (PFA). One or a mixture of two or more selected from these can be used as the second resin material.

In this embodiment, the degree of hydrophilicity and hydrophobicity of a resin material can be determined by the equivalent weight (EW) of the resin material. The equivalent weight is a value indicating the amount of ion exchange groups in the resin material, and represents the number of grams of dry resin material containing 1 mole of proton-conducting groups (unit: g/mol). The larger the equivalent weight, the lower the hydrophilicity of the resin material. The smaller the equivalent weight, the higher the hydrophilicity of the resin material. The equivalent weight can be determined by ¹ H-NMR measurement. The presence of the first resin material and the second resin material in the cathode catalyst layer 109 can be determined by ¹ H-NMR measurement.

The equivalent mass of the first resin material may be smaller than the equivalent mass of the second resin material. This configuration allows the pores 14 to be highly hydrophobic while maintaining proton conductivity. This further improves the drainage properties of the cathode catalyst layer 109.

The first resin material may contain, for example, a polymer material having an equivalent mass of 500 g/mol or more and 1100 g/mol or less. This configuration can impart high proton conductivity to the conductive fibers 13.

The second resin material may contain, for example, a polymer material with an equivalent mass of 1200 g/mol or more and 2000 g/mol or less. This configuration can impart high hydrophobicity to the pores 14. This can further improve the drainage properties of the cathode catalyst layer 109.

The contact angle θ2 of the thin film made of the second resin material with water may be at least 20 degrees greater than the contact angle θ1 of the thin film made of the first resin material with water. This configuration can impart proton conductivity and drainage properties to the conductive fiber 13. There is no particular upper limit to the difference between the contact angle θ2 and the contact angle θ1 (θ2 - θ1), and it can be, for example, 120 degrees. The contact angle (static contact angle) can be measured in accordance with the provisions of Japanese Industrial Standards (JIS) R3257:1999.

In this embodiment, the ratio of the total mass of the first resin material and the second resin material to the total mass of the carrier particles 11 and the conductive fibers 13 is, for example, in the range of 0.80 to 1.50. With this configuration, the resin material 15 can be uniformly adhered to the surface of the conductive fibers 13. As a result, the proton conduction pathway within the cathode catalyst layer 109 is less likely to be interrupted. As a result, a cathode catalyst layer 109 with high proton conductivity is obtained.

The average length of the conductive fibers 13 may be greater than the average particle size of the support particles 11. With this configuration, pores 14 are more likely to form between the particles of the electrode catalyst 10 connected by the conductive fibers 13.

In the cathode catalyst layer 109, the ratio of the mass of the conductive fibers 13 to the total mass of the support particles 11, catalyst particles 12, and conductive fibers is, for example, in the range of 0.20 to 0.50. This configuration improves the proton conductivity and drainage performance of the cathode catalyst layer 109. The conductive fibers 13 can be separated from the electrode catalyst 10 by centrifugation.

Figure 4 is a process diagram showing the manufacturing method of the cathode catalyst layer 109.

In step S1, a preliminary solution is prepared by mixing carrier particles 11 carrying catalyst particles 12, conductive fibers 13, a first resin material having proton conductivity, and a solvent. The carrier particles 11 carrying catalyst particles 12 can be prepared by a known method (Patent Document 2). Examples of the solvent include water, ethanol, and mixtures thereof. The preliminary solution is obtained by uniformly dispersing the carrier particles 11 carrying catalyst particles 12, the conductive fibers 13, and the first resin material in the solvent. In the preliminary solution, the first resin material adheres to the surfaces of the conductive fibers 13, forming a first resin layer 15a.

In step S2, the second resin material is dispersed in the preliminary solution to prepare the catalyst ink. The second resin material can be uniformly dispersed in the catalyst ink.

In step S3, the catalyst ink is applied to a substrate to form a catalyst layer. The substrate is the electrolyte membrane 102, the cathode gas diffusion layer 110, or a transfer film. An example of a catalyst layer is the cathode catalyst layer 109. When the catalyst ink is applied to the substrate and the solvent is removed from the applied film by heating or the like, the second resin material adheres to the outer surface of the first resin layer 15a. This forms the second resin layer 15b. According to the manufacturing method of this embodiment, a catalyst layer having the structure described with reference to Figures 2 and 3 can be efficiently manufactured.

Before proceeding to step S2, the preliminary solution may be held for a predetermined time. The predetermined time may be, for example, 1 to 10 hours. This allows the first resin material to be sufficiently adsorbed onto the surface of the conductive fibers 13. Holding the preliminary solution may also mean allowing the preliminary solution to stand.

[1-2. Operation]
The operation and function of the fuel cell 101 configured as above will be explained below with reference to FIG.

A hydrogen-containing gas is supplied to the anode gas flow channel 107. An oxidant gas is supplied to the cathode gas flow channel 112. The oxidant gas is typically air. At the anode 103, hydrogen (H ₂ ) splits into protons (H ⁺ ) and electrons (e ⁻ ) in an electrochemical reaction represented by the following formula (1). The protons travel through the electrolyte membrane 102 from the anode 103 to the cathode 108. The electrons travel from the anode 103 to the cathode 108 through an external circuit. At the cathode 108, water (H ₂ O) is produced by an electrochemical reaction of protons, oxygen (O ₂ ), and electrons in the following formula (2):

H ₂ →2H ⁺ +2e ^- (1)
4H ⁺ +O ₂ +2e ^- →2H ₂ O(2)

[1-3. Supplementary notes]
The above description of the embodiments discloses the following techniques.

(Technology 1)
Carrier particles;
catalyst particles supported on the support particles;
Conductive fibers arranged in contact with the carrier particles;
a first resin layer containing a first resin material having proton conductivity and covering at least a part of the surface of the conductive fiber;
a second resin layer including a second resin material having a lower hydrophilicity than the first resin material and covering at least a portion of an outer surface of the first resin layer;
A catalyst layer for a membrane electrode assembly, comprising:

(Technology 2)
A catalyst layer for a membrane electrode assembly, comprising:
Carrier particles;
catalyst particles supported on the support particles;
Conductive fibers arranged in contact with the carrier particles;
a resin material attached to the conductive fiber;
Equipped with
the resin material includes a first resin material having proton conductivity and a second resin material having lower hydrophilicity than the first resin material;
the proton conduction resistance of the catalyst layer measured when AC impedance of the membrane electrode assembly including the catalyst layer is measured under conditions of a temperature of 50°C and a relative humidity of 100% is 250 mΩ/ ^cm2 or less;
Catalyst layer for membrane electrode assembly.

Technologies 1 and 2 enable the catalyst layer to achieve both proton conductivity and drainage, improving the efficiency of the electrochemical reaction.

(Technology 3)
3. The catalyst layer for a membrane electrode assembly according to claim 1, wherein the first resin material contains a polymer electrolyte. With this configuration, high proton conductivity can be imparted to the conductive fiber.

(Technology 4)
The catalyst layer for a membrane electrode assembly according to any one of techniques 1 to 3, wherein the second resin material includes a polymer material having no proton-conducting functional groups. With this configuration, the pores can have high hydrophobicity.

(Technology 5)
5. The catalyst layer for a membrane electrode assembly according to any one of claims 1 to 4, wherein the equivalent mass of the first resin material is smaller than the equivalent mass of the second resin material. With this configuration, it is possible to impart high hydrophobicity to the pores while maintaining proton conductivity.

(Technology 6)
6. The catalyst layer for a membrane electrode assembly according to any one of claims 1 to 5, wherein the second resin material includes a polymer material having an equivalent mass of 1200 g/mol or more and 2000 g/mol or less. With this configuration, high hydrophobicity can be imparted to the pores.

(Technology 7)
7. The catalyst layer for a membrane electrode assembly according to any one of claims 1 to 6, wherein a contact angle of the thin film made of the second resin material with water is 20 degrees or more larger than a contact angle of the thin film made of the first resin material with water. With this configuration, proton conductivity and drainage property can be imparted to the conductive fiber.

(Technology 8)
8. The catalyst layer for a membrane electrode assembly according to claim 1, wherein a ratio of a total mass of the first resin material and the second resin material to a total mass of the carrier particles and the conductive fibers is in a range of 0.80 to 1.50. With this configuration, the resin material 15 can be uniformly adhered to the surface of the conductive fibers.

(Technology 9)
The catalyst layer for a membrane electrode assembly according to any one of techniques 1 to 8, wherein the conductive fibers have an average length greater than an average particle size of the support particles. With this configuration, pores are likely to be formed between the electrode catalyst particles connected by the conductive fibers.

(Technology 10)
10. The catalyst layer for a membrane electrode assembly according to any one of claims 1 to 9, wherein a ratio of the mass of the conductive fibers to the total mass of the support particles, the catalyst particles, and the conductive fibers is in the range of 0.20 to 0.50. With this configuration, it is possible to improve proton conductivity and drainage property in the catalyst layer.

(Technology 11)
an anode;
a cathode;
an electrolyte membrane disposed between the anode and the cathode;
Equipped with
The cathode comprises a catalyst layer according to any one of techniques 1 to 10;
Membrane electrode assembly.

Technology 11 can improve the efficiency of electrochemical reactions.

(Technology 12)
preparing a preliminary solution by mixing carrier particles carrying catalyst particles, conductive fibers, a first resin material having proton conductivity, and a solvent;
preparing a catalyst ink by dispersing a second resin material having a lower hydrophilicity than the first resin material in the preliminary solution;
applying the catalyst ink to a substrate to form a catalyst layer;
A method for producing a catalyst layer for a membrane electrode assembly, comprising:

The manufacturing method of the present disclosure allows for efficient production of the catalyst layer of the present disclosure.

The technology disclosed herein is useful for electrochemical devices such as secondary batteries, fuel cells, and hydrogen purification devices.

10 Electrode catalyst 11 Carrier particle 12 Catalyst particle 13 Conductive fiber 14 Pore 15 Resin material 15a First resin layer 15b Second resin layer 101 Fuel cell 102 Electrolyte membrane 103 Anode 104 Anode catalyst layer 105 Anode gas diffusion layer 106 Anode separator 107 Anode gas flow channel 108 Cathode 109 Cathode catalyst layer 110 Cathode gas diffusion layer 111 Cathode separator 112 Cathode gas flow channel 113 Membrane electrode assembly

Claims (12)

Carrier particles;
catalyst particles supported on the support particles;
Conductive fibers arranged in contact with the carrier particles;
a first resin layer containing a first resin material having proton conductivity and covering at least a part of the surface of the conductive fiber;
a second resin layer including a second resin material having a lower hydrophilicity than the first resin material and covering at least a portion of an outer surface of the first resin layer;
A catalyst layer for a membrane electrode assembly, comprising: A catalyst layer for a membrane electrode assembly, comprising:
Carrier particles;
catalyst particles supported on the support particles;
Conductive fibers arranged in contact with the carrier particles;
a resin material attached to the conductive fiber;
Equipped with
the resin material includes a first resin material having proton conductivity and a second resin material having lower hydrophilicity than the first resin material;
the proton conduction resistance of the catalyst layer measured when AC impedance of the membrane electrode assembly including the catalyst layer is measured under conditions of a temperature of 50°C and a relative humidity of 100% is 250 mΩ/ ^cm2 or less;
Catalyst layer for membrane electrode assembly. the first resin material contains a polymer electrolyte;
The catalyst layer for a membrane electrode assembly according to claim 1 or 2. the second resin material includes a polymer material having no proton-conductive functional group;
The catalyst layer for a membrane electrode assembly according to claim 1 or 2. the equivalent mass of the first resin material is smaller than the equivalent mass of the second resin material;
The catalyst layer for a membrane electrode assembly according to claim 1 or 2. the second resin material includes a polymer material having an equivalent mass of 1200 g/mol or more and 2000 g/mol or less;
The catalyst layer for a membrane electrode assembly according to claim 1 or 2. a contact angle of the thin film made of the second resin material with water that is 20 degrees or more larger than a contact angle of the thin film made of the first resin material with water;
The catalyst layer for a membrane electrode assembly according to claim 1 or 2. a ratio of the total mass of the first resin material and the second resin material to the total mass of the carrier particles and the conductive fibers is in the range of 0.80 to 1.50;
The catalyst layer for a membrane electrode assembly according to claim 1 or 2. The average length of the conductive fibers is greater than the average particle size of the carrier particles.
The catalyst layer for a membrane electrode assembly according to claim 1 or 2. a ratio of the mass of the conductive fibers to the total mass of the support particles, the catalyst particles, and the conductive fibers is in the range of 0.20 to 0.50;
The catalyst layer for a membrane electrode assembly according to claim 1 or 2. an anode;
a cathode;
an electrolyte membrane disposed between the anode and the cathode;
Equipped with
The cathode comprises the catalyst layer according to claim 1 or 2.
Membrane electrode assembly. preparing a preliminary solution by mixing carrier particles carrying catalyst particles, conductive fibers, a first resin material having proton conductivity, and a solvent;
preparing a catalyst ink by dispersing a second resin material having a lower hydrophilicity than the first resin material in the preliminary solution;
applying the catalyst ink to a substrate to form a catalyst layer;
A method for producing a catalyst layer for a membrane electrode assembly, comprising: