JP2023176353A - electrode catalyst layer - Google Patents

Abstract

To provide an electrode catalyst layer for a polymer fuel battery, in which drainage or a gas diffusion property can be improved, and a high output can be made.SOLUTION: An electrode catalyst layer bonded to a polymer fuel electrolyte membrane, includes: a catalysis 13; a conductive carrier 14 carrying the catalysis 13; a polymer electrolyte 15; and a fiber state material 16. In a first cross section as a cross section of a thickness direction, a distance between the adjacent first fiber state materials is 0.30 μm or more and 8 μm or less.SELECTED DRAWING: Figure 1

Description

The present invention relates to an electrode catalyst layer constituting a membrane electrode assembly for polymer fuel cells.

In recent years, fuel cells have attracted attention as an effective solution to environmental and energy problems. A fuel cell oxidizes a fuel such as hydrogen using an oxidizing agent such as oxygen, and converts the associated chemical energy into electrical energy.
Fuel cells are classified into alkaline type, phosphoric acid type, polymer type, molten carbonate type, solid oxide type, etc. depending on the type of electrolyte. Polymer fuel cells (PEFCs) operate at low temperatures, have high output density, and can be made smaller and lighter, so they are expected to be used as portable power sources, household power sources, and in-vehicle power sources. There is.

A polymer fuel cell (PEFC) is equipped with a membrane electrode assembly in which a polymer electrolyte membrane is sandwiched between a pair of electrodes consisting of a fuel electrode (anode) and an air electrode (cathode). By supplying fuel gas containing hydrogen and oxidant gas containing oxygen to the air electrode side, power is generated through the electrochemical reaction described below.

Anode: H ₂ → 2H ⁺ + 2e ^- (1)
Cathode: 1/2O ₂ + 2H ⁺ + 2e ^- → H ₂ O...(2)
The anode and cathode each have a laminated structure of an electrode catalyst layer and a gas diffusion layer. The fuel gas supplied to the anode side electrode catalyst layer is converted into protons and electrons by the electrode catalyst (reaction 1). Protons pass through the polymer electrolyte and polymer electrolyte membrane in the anode-side electrode catalyst layer and move to the cathode. Electrons travel through an external circuit to the cathode. In the electrode catalyst layer on the cathode side, protons, electrons, and an oxidant gas supplied from the outside react to generate water (reaction 2). In this way, electricity is generated by the electrons passing through the external circuit.

Currently, in order to reduce the cost of fuel cells, fuel cells that exhibit high output characteristics are desired. However, in a fuel cell, a large amount of generated water is generated during high-output operation, so water overflows into the electrode catalyst layer and the gas diffusion layer, resulting in footing that obstructs the supply of gas. When footing occurs, there is a problem in that the output of the fuel cell is significantly reduced.

To address the above problem, Patent Documents 1 and 2 propose catalyst layers containing carbon or carbon fibers of different particle sizes.

Japanese Patent Application Publication No. 10-241703 Patent No. 5537178

Patent Documents 1 and 2 describe that by including different carbon materials, pores are generated in the electrode catalyst layer, and improvement in drainage performance and gas diffusivity can be expected. However, increasing the porosity within the electrode catalyst layer increases the thickness of the electrode catalyst layer, increases the distance that electrons or protons travel, and increases resistance. This reduces power generation performance. Furthermore, although there is a description of the size, shape, and content of the carbon material, there is no description of the structure of the catalyst layer, and its effects have not been specifically verified.
The invention was made in view of the above circumstances, and an object of the invention is to provide an electrode catalyst layer for a polymer fuel cell that can improve drainage performance and gas diffusivity and can achieve high output. .

In order to solve the above problems, one embodiment of the present invention provides an electrode catalyst layer joined to a polymer electrolyte membrane, which includes a catalyst, a conductive carrier supporting the catalyst, a polymer electrolyte, and a fibrous electrolyte. The gist is that the distance between adjacent first fibrous substances is 0.30 μm or more and 8 μm or less in a first cross section that is a cross section in the thickness direction.

According to one aspect of the present invention, it is possible to provide a catalyst layer for a polymer fuel cell that can improve drainage performance and gas diffusivity and can provide high output without increasing the thickness more than necessary.

1 is a diagram schematically showing the structure of an electrode catalyst layer included in a membrane electrode assembly according to an embodiment of the present invention. FIG. 2 is a cross-sectional view illustrating the structure of an electrode catalyst layer according to an embodiment of the present invention. FIG. 1 is a cross-sectional view illustrating the structure of a membrane electrode assembly according to an embodiment of the present invention. FIG. 1 is an exploded perspective view showing the internal structure of a single cell of a polymer electrolyte fuel cell according to an embodiment of the present invention.

Embodiments of the present invention will be described below with reference to the drawings.
Note that the present invention is not limited to the embodiments described below, and modifications such as changes in design can be made based on the knowledge of those skilled in the art. Other embodiments are also included within the scope of the present invention.

(electrode catalyst layer)
As shown in FIG. 1, the electrode catalyst layers 2 and 3 for a polymer fuel cell according to the present embodiment are made of a catalyst 13, a conductive carrier 14 supporting the catalyst 13, a polymer electrolyte 15, and a fibrous material 16. Become.
In addition, as shown in FIG. 2, the electrode catalyst layers 2 and 3 of this embodiment have an arbitrary fibrous material and are close to the fibrous material in the first cross section cut in the thickness direction of the electrode catalyst layer. The distance to other fibrous substances is set to 0.30 μm or more and 8 μm or less. That is, in the first cross section, the distance between adjacent fibrous substances is set to 0.30 μm or more and 8 μm or less.
Since the electrode catalyst layers 2 and 3 contain the fibrous material 16, cracks do not occur during formation of the electrode catalyst layers 2 and 3, and it becomes possible to increase the number of pores in the electrode catalyst layers 2 and 3. . Furthermore, by keeping the distance between the respective fibrous substances 16 within the above-mentioned predetermined range, the fibrous substances 16 can be used efficiently, and the thickness of the electrode catalyst layers 2 and 3 can be increased, and the electron or This can prevent protons from traveling over long distances.
Further, also in the second cross section perpendicular to the first cross section, the distance between adjacent fibrous substances 16 is preferably 0.30 μm or more and 8 μm or less. When set in this way, the effect of the fibrous material 16 can be obtained in all directions of the electrode catalyst layers 2 and 3.

The distance between the fibrous substances 16 is determined by the distance between each exposed fibrous substance when a cross section of the electrode catalyst layers 2 and 3 as shown in FIG. 2 is observed using a scanning electron microscope (SEM). It can be obtained by measuring the length between the centers of the exposed cross sections of No. 16. That is, in this embodiment, the distance between the fibrous substances 16 mentioned above refers to the distance between the centers of each cross section of the two fibrous substances 16.
Note that when the fibrous material 16 is cut obliquely in cross section, the exposed cross section may have an elliptical shape. In that case, the distance between the fibrous substances 16 can be obtained by measuring the center of a perfect circle fitted along the short axis. The observation magnification in a scanning electron microscope (SEM) is preferably set to 6000 times, and all the fibrous substances 16 are measured, since the distance between the fibrous substances 16 in the entire catalyst layer can be measured.

As a method for exposing the cross section of the electrode catalyst layers 2 and 3, for example, ion milling, ultramicrotome, etc. can be used. When processing to expose the cross section, processing is performed while cooling the membrane electrode assembly 12 in order to reduce damage to the polymer electrolyte 15 that constitutes the polymer electrolyte membrane 1 and the electrode catalyst layers 2 and 3. It is preferable to use cryo-ion milling, especially since a clear cross section can be obtained.

The thickness of the electrode catalyst layers 2 and 3 is preferably 30 μm or less, more preferably 10 μm. If the thickness is greater than 30 μm, the resistance of the electrode catalyst layers 2 and 3 will increase and the output will decrease. Moreover, cracks are likely to occur in the electrode catalyst layers 2 and 3, which is not preferable.
The thickness of the electrode catalyst layers 2 and 3 is preferably 1 μm or more. When the thickness is thinner than 1 μm, variations in layer thickness tend to occur, and the internal catalyst 13 and polymer electrolyte 15 tend to become non-uniform. Cracks on the surface of the electrode catalyst layers 2 and 3 and non-uniformity in thickness are undesirable because they are highly likely to have a negative effect on durability when used as a fuel cell and operated over a long period of time. Further, in the electrode catalyst layers 2 and 3, the concentration of water produced by power generation tends to increase, flooding tends to occur, and power generation performance deteriorates, which is not preferable.

<Polymer electrolyte>
The polymer electrolyte 15 may be any material that has ion conductivity, but considering the adhesion between the electrode catalyst layers 2 and 3 and the polymer electrolyte membrane, it is recommended to select a material that is the same as the polymer electrolyte membrane. preferable. The polymer electrolyte 15 can be made of, for example, a fluororesin or a hydrocarbon resin. For example, examples of the fluororesin include Nafion (manufactured by Chemours, registered trademark), and examples of the hydrocarbon resin include engineering plastics or copolymers thereof with sulfonic acid groups introduced therein.

<Catalyst>
As the catalyst 13, platinum group elements, metals, alloys thereof, oxides, double oxides, etc. can be used. Platinum group elements include platinum, palladium, ruthenium, iridium, rhodium, and osmium. Examples of metals include iron, lead, copper, chromium, cobalt, nickel, manganese, vanadium, molybdenum, gallium, and aluminum. Among these, platinum or a platinum alloy is preferable as the catalyst 13. Furthermore, if the particle size of these catalysts 13 is too large, the activity of the catalyst 13 will be reduced, and if it is too small, the stability of the catalyst 13 will be reduced, so it is preferably 0.5 to 20 nm. More preferably, the thickness is 1 to 5 nm.

<Conductive carrier>
As the conductive carrier 14, any carrier may be used as long as it is in the form of fine particles, has conductivity, and is not affected by the catalyst 13. An example of the conductive carrier 14 is carbon particles. If the particle size of the conductive carrier 14 is too small, it will be difficult to form an electron conduction path, and if it is too large, the electrode catalyst layers 2 and 3 will become thicker and the resistance will increase, resulting in a decrease in output characteristics. The thickness is preferably about 10 to 1000 nm. More preferably, the thickness is 10 to 100 nm. Further, by supporting the catalyst 13 on the conductive carrier 14 having a high surface area, the catalyst 13 can be supported at high density, and the catalytic activity can be improved.

<Fibrous substance>
The fibrous material 16 may be any material as long as it can maintain its fibrous shape without being attacked by the catalyst 13 and the polymer electrolyte 15. In order to lower the resistance of the electrode catalyst layers 2 and 3, the fibrous material 16 preferably exhibits electron conductivity or proton conductivity.
As the fibrous material 16 exhibiting electron conductivity, carbon fibers, carbon nanofibers, and carbon nanotubes can be used. Preferable examples include carbon nanofibers and carbon nanotubes.
Examples of the fibrous material 16 exhibiting proton conductivity include fibers obtained by processing a polymer electrolyte into a fibrous form. As the polymer electrolyte, fluorine-based resins and hydrocarbon-based resins can be used. For example, the fluorine-based resin is Nafion (manufactured by Chemours, registered trademark), and the hydrocarbon-based resin is engineering plastics or their co-resins. Examples include polymers with sulfonic acid groups introduced therein. Furthermore, acid-doped polybenzazoles that exhibit proton conductivity by doping with acid can also be suitably used.

Further, examples of the fibrous material 16 include resin fibers having basic functional groups capable of interacting with acidic substances in the main chain skeleton or side chain functional groups. By interacting with the acidic substance contained in the polymer electrolyte 15, the surface of the resin fiber is coated with the polymer electrolyte, making it possible to exhibit proton conductivity. Examples of basic functional groups that can interact with acidic substances include =N- group, -NH2 group, >NH group, >N- group, ammonium group, amine derivative, pyridine derivative, imidazole derivative, imidazolium group, etc. be able to. Specific resin fibers include polybenzimidazole (PBI), polybenzoxazole, polybenzthioazole, polyvinylimidazole, polyallylamine, etc. In particular, from the viewpoint of proton conductivity and processing, azole structures are preferred. Preferred is polybenzimidazole (PBI) with

The fiber diameter of the fibrous substance 16 is preferably 0.5 to 500 nm, more preferably 10 to 300 nm. By setting it within the above range, the number of pores in the electrode catalyst layers 2 and 3 can be increased, and high output can be achieved.

The fiber length of the fibrous substance 16 is preferably 1 to 200 μm, more preferably 1 to 50 μm. By setting it within the above range, the strength of the electrode catalyst layers 2 and 3 can be increased, and cracks can be suppressed from occurring during formation. In addition, the number of pores in the electrode catalyst layers 2 and 3 can be increased, making it possible to increase the output.

(Membrane electrode assembly)
The membrane electrode assembly 12 for a polymer fuel cell according to this embodiment has a structure as shown in the cross-sectional view shown in FIG. 3, for example. This membrane electrode assembly 12 includes a polymer electrolyte membrane 1, a cathode electrode catalyst layer 2 formed on one surface of the polymer electrolyte membrane 1, and an anode formed on the other surface of the polymer electrolyte membrane 1. It has a structure including a side electrode catalyst layer 3.
One or both of the cathode side electrode catalyst layer 2 and the anode side electrode catalyst layer 3 consists of the electrode catalyst layer of this embodiment described above.

(Polymer electrolyte fuel cell)
As shown in FIG. 4, in the polymer electrolyte fuel cell of this embodiment, the air electrode side is opposite to the cathode side electrode catalyst layer 2 and the anode side electrode catalyst layer 3 of the membrane electrode assembly 12 of this embodiment. A gas diffusion layer 4 and a fuel electrode side gas diffusion layer 5 are respectively arranged. As a result, the cathode side electrode catalyst layer 2 and the air electrode side gas diffusion layer 4 constitute the air electrode 6, and the anode side electrode catalyst layer 3 and the fuel electrode side gas diffusion layer 5 constitute the fuel electrode 7. Ru. Then, by sandwiching the air electrode 6 and the fuel electrode 7 between a set of separators 10, a single cell polymer electrolyte fuel cell 11 is constructed. A set of separators 10 is made of an electrically conductive and gas impermeable material, and is a gas flow path for reactant gas distribution arranged facing the air electrode side gas diffusion layer 4 or the fuel electrode side gas diffusion layer 5. 8, and a cooling water flow path 9 for circulating cooling water disposed on the main surface facing the gas flow path 8.

In this polymer electrolyte fuel cell 11, an oxidizing agent such as air or oxygen is supplied to the air electrode 6 through the gas passage 8 of one separator 10, and hydrogen is supplied through the gas passage 8 of the other separator 10. Power is generated by supplying fuel gas or organic fuel containing fuel to the fuel electrode 7.

(Method for manufacturing electrode catalyst layer)
The electrode catalyst layer can be manufactured by preparing a catalyst layer slurry, applying the prepared catalyst layer slurry to a base material, etc., and drying it.

The catalyst layer slurry includes a catalyst 13, a conductive carrier 14, a polymer electrolyte 15, a fibrous material 16, and a solvent. An example of the fibrous material 16 is carbon fiber.
The solvent is not particularly limited, but a solvent that can disperse or dissolve the polymer electrolyte 15 is preferable. Commonly used solvents include water, alcohols such as methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, isobutyl alcohol, and tert-butyl alcohol, acetone, methyl ethyl ketone, and methyl propyl ketone. Ketones such as , methyl butyl ketone, methyl isobutyl ketone, methyl amyl ketone, pentanone, heptanone, cyclohexanone, methyl cyclohexanone, acetonylacetone, diethyl ketone, dipropyl ketone, diisobutyl ketone, tetrahydrofuran, tetrahydropyran, dioxane, diethylene glycol Ethers such as dimethyl ether, anisole, methoxytoluene, diethyl ether, dipropyl ether, dibutyl ether, amines such as isopropylamine, butylamine, isobutylamine, cyclohexylamine, diethylamine, aniline, propyl formate, isobutyl formate, amyl formate, acetic acid Esters such as methyl, ethyl acetate, propyl acetate, butyl acetate, isobutyl acetate, pentyl acetate, isopentyl acetate, methyl propionate, ethyl propionate, butyl propionate, other acetic acid, propionic acid, dimethylformamide, dimethylacetamide, N- Methylpyrrolidone or the like may also be used. In addition, as glycol and glycol ether solvents, ethylene glycol, diethylene glycol, propylene glycol, ethylene glycol monomethyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diacetone alcohol, 1-methoxy-2-propanol, 1-ethoxy-2 - Examples include propanol.

Examples of the method for applying the slurry for the catalyst layer include a doctor blade method, a die coating method, a dipping method, a screen printing method, a laminator roll coating method, and a spray method, but the method is not particularly limited.

Examples of methods for drying the catalyst layer slurry include hot air drying and IR drying. The drying temperature is about 40 to 200°C, preferably about 40 to 120°C. The drying time is about 0.5 minutes to 1 hour, preferably about 1 minute to 30 minutes.

Here, in order to set the distance between the fibrous substances in the electrode catalyst layer to 0.30 μm or more and 8 μm or less, the amount of carbon fiber added, the fiber length, the heating temperature for drying, the temperature gradient, and the electrode catalyst layer must be adjusted. This can be achieved by adjusting conditions such as pressure applied in the film thickness direction until drying.

(Method for manufacturing membrane electrode assembly)
Methods for manufacturing membrane electrode assemblies include forming an electrode catalyst layer on a transfer base material or gas diffusion layer, and forming an electrode catalyst layer on a polymer electrolyte membrane by thermocompression bonding, or directly forming a catalyst layer on a polymer electrolyte membrane. Examples include a method of forming. The method of forming the catalyst layer directly on the polymer electrolyte membrane is preferable because the adhesiveness between the polymer electrolyte membrane and the catalyst layer is high and there is no risk of the catalyst layer being crushed.

As explained above, the electrode catalyst layer of the present embodiment includes a catalyst, a conductive carrier supporting the catalyst, a polymer electrolyte, and a fibrous material, and the electrode catalyst layer includes a catalyst, a conductive carrier supporting the catalyst, a polymer electrolyte, and a fibrous material. In the cross section of No. 1, the distance between the fibrous substances is 0.30 μm or more and 8 μm or less.
According to this configuration, it is possible to improve drainage performance and gas diffusivity without increasing the thickness of the electrode catalyst layer more than necessary, and to provide an electrode catalyst layer for a polymer fuel cell capable of high output. can.
The electrode catalyst layer of this embodiment is extremely suitable for application to, for example, a polymer electrolyte fuel cell.

(others)
The present disclosure can also take the following configuration.
(1) An electrode catalyst layer bonded to a polymer electrolyte membrane,
comprising a catalyst, a conductive carrier supporting the catalyst, a polymer electrolyte, and a fibrous material,
An electrode catalyst layer in which a distance between adjacent first fibrous substances is 0.30 μm or more and 8 μm or less in a first cross section that is a cross section in the thickness direction.
(2) In the second cross section orthogonal to the first cross section, the distance between adjacent fibrous substances is 0.30 μm or more and 8 μm or less.
(3) The fibrous material exhibits at least one of electron conductivity and proton conductivity.
(4) The fibrous substance contains an azole structure.
(5) The content of the fibrous substance in the electrode catalyst layer is 1% by weight or more and 15% by weight or less.
(6) The thickness of the electrode catalyst layer is 1 μm or more and 30 μm or less.

Next, an example based on this embodiment will be described.
[Calculation of distance between fibrous substances]
A cross-section of the electrode catalyst layer was obtained using cryo-ion milling, and a cross-sectional image (6000 times) of the electrode catalyst layer was obtained using a scanning electron microscope (SEM). The distance between each fibrous substance was measured from the image. The distance was determined using the method described in the embodiment.
[Evaluation of power generation characteristics]
A gas diffusion layer (SIGRACET(R) 22BC, manufactured by SGL) was placed outside the electrode catalyst layer, and power generation characteristics were evaluated using a commercially available JARI standard cell. The cell temperature was 80° C., and hydrogen (100% RH) was supplied to the anode and air (100% RH) to the cathode.

[Example 1]
In Embodiment 1, 20 g of platinum-supported carbon (TEC10E50E, manufactured by Tanaka Kikinzoku Co., Ltd.) is placed in a container, water is added and mixed, and then 1-propanol, electrolyte (Nafion (registered trademark) dispersion liquid, Wako Pure Chemical Industries, Ltd.) and fibrous As a substance, 10 g of carbon nanofibers (manufactured by Showa Denko K.K., trade name "VGCF", fiber diameter approximately 150 nm, fiber length approximately 10 μm) were added and stirred to obtain a slurry for a catalyst layer. The obtained catalyst layer slurry was applied to a polymer electrolyte membrane (Nafion 212, manufactured by Chemours) using a die coating method, and dried in an oven to form the membrane electrode assembly having the electrode catalyst layer of Example 1. Obtained. The composition and drying temperature of the catalyst layer slurry were adjusted so that the distance between the fibrous substances was 0.30 μm or more and 8 μm or less.

[Example 2]
The electrode catalyst layer (cathode) of Example 2 was prepared in the same manner as in Example 1, except that resin fibers having an azole structure (fiber diameter of about 200 nm, fiber length of about 20 μm) were used as the fibrous material.
[Example 3]
A membrane electrode assembly having the electrode catalyst layer (cathode) of Example 3 was obtained in the same manner as in Example 1 except that the amount of fibrous material was increased.
[Comparative example 1]
A membrane electrode assembly having the electrode catalyst layer (cathode) of Comparative Example 1 was obtained in the same manner as in Example 3, except that the stirring time when preparing the catalyst layer slurry was shortened.
[Comparative example 2]
A membrane electrode assembly having the electrode catalyst layer (cathode) of Comparative Example 2 was obtained in the same manner as in Example 1, except that it was coated on a PET base material and transferred to an electrolyte membrane by thermocompression bonding.
[Comparative example 3]
The electrode catalyst layer (cathode) of Comparative Example 3 was prepared in the same manner as in Example 1, except that the composition and coating amount of the slurry were adjusted and applied so that the thickness of the electrode catalyst layer was less than 1 μm. A membrane electrode assembly was obtained.
[Comparative example 4]
The electrode catalyst layer (cathode) of Comparative Example 4 was prepared in the same manner as in Example 1, except that the slurry composition and coating amount were adjusted so that the thickness of the electrode catalyst layer exceeded 30 μm. A membrane electrode assembly was obtained.
[Comparative example 5]
A membrane electrode assembly having an electrode catalyst layer of Comparative Example 5 was obtained in the same manner as in Example 1 except that no fibrous material was added.

(evaluation)
Each of the electrode catalyst layers of Examples 1 to 3 and Comparative Examples 1 to 5 was observed with a microscope (magnification: 200 times) to evaluate the presence or absence of cracks of 10 μm or more.
The evaluation results are shown in Table 1.

As shown in Table 1, many cracks occurred when no fibrous material was added (Comparative Example 5). On the other hand, when fibrous substances were added as in Examples and Comparative Examples 1 to 4, the catalyst layer was free of cracks.

Furthermore, the thickness of the electrode catalyst layer, the distance between the fibrous materials, and the power generation characteristics of the electrode catalyst layers of Examples 1 to 3 and Comparative Examples 1 to 4 were evaluated. The evaluation results are shown in Table 2.
In Examples 1 and 2, even in the cross section (second cross section) perpendicular to the cross section (first cross section) in Table 2, the distance between the fibrous substances was 0.30 μm or more and 8 μm or less.
Here, in each electrode catalyst layer, the mass of the catalyst blended is adjusted to be the same, but since the other configurations are different, the thickness of each electrode catalyst layer is different.

From Tables 1 and 2, it can be seen that the catalyst includes a catalyst, a conductive carrier supporting the catalyst, a polymer electrolyte, and a fibrous material, and the distance between the fibrous materials is 0 in the first cross section in the thickness direction. By being 30 μm or more and 8 μm or less, cracks will not occur in the membrane electrode assembly, and even if the materials contained in the electrode catalyst layer are the same (Example 1, Comparative Example 2), drainage performance and gas diffusivity will be improved. It was found that an electrode catalyst layer for polymer fuel cells capable of high output can be provided.

1 Polymer electrolyte membrane 2 Cathode side electrode catalyst layer 3 Anode side electrode catalyst layer 4 Air electrode side gas diffusion layer 5 Fuel electrode side gas diffusion layer 6 Air electrode 7 Fuel electrode 8 Gas flow path 9 Cooling water flow path 10 Separator 11 Solid height Molecular fuel cell 12 Membrane electrode assembly 13 Catalyst 14 Conductive carrier 15 Polymer electrolyte 16 Fibrous material

Claims (6)

An electrode catalyst layer bonded to a polymer electrolyte membrane,
comprising a catalyst, a conductive carrier supporting the catalyst, a polymer electrolyte, and a fibrous material,
In the first cross section that is the cross section in the thickness direction, the distance between adjacent first fibrous substances is 0.30 μm or more and 8 μm or less,
An electrode catalyst layer characterized by: In a second cross section orthogonal to the first cross section, the distance between adjacent fibrous substances is 0.30 μm or more and 8 μm or less,
The electrode catalyst layer according to claim 1, characterized in that: The electrode catalyst layer according to claim 1, wherein the fibrous material exhibits at least one of electron conductivity and proton conductivity. The electrode catalyst layer according to claim 3, wherein the fibrous material contains an azole structure. The content of the fibrous substance in the electrode catalyst layer is 1% by weight or more and 15% by weight or less,
The electrode catalyst layer according to any one of claims 1 to 4, characterized in that: The electrode catalyst layer according to claim 1, wherein the thickness of the electrode catalyst layer is 1 μm or more and 30 μm or less.

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