WO2019224729A2

WO2019224729A2 - Catalyst layer ink and production method for fuel cell

Info

Publication number: WO2019224729A2
Application number: PCT/IB2019/054212
Authority: WO
Inventors: 高椋庄吾
Original assignee: ローベルトボッシュゲゼルシャフトミットベシュレンクテルハフツング
Priority date: 2018-05-25
Filing date: 2019-05-22
Publication date: 2019-11-28
Also published as: JP2019202287A; WO2019224729A3

Abstract

Provided is a catalyst layer ink that enables the formation of a catalyst layer in which ionomers are present within the pores of a carrier. This method for producing a catalyst layer ink that includes ionomers, a catalyst, a carrier having pores, and a solvent, comprises: a step in which the ionomers in the catalyst layer ink are a polymer comprising an acidic functional group or a precursor thereof, and the ionomer material is mixed with the solvent, the carrier and the catalyst to obtain a mixture; and a step in which the material is reacted in the mixture to produce ionomers, thereby providing the catalyst layer ink.

Description

〇 2019/224729 卩（： 17132019/054212

1

[Document Name] Statement

Patent application title: CATALYST LAYER INK AND FUEL CELL MANUFACTURING METHOD

【Technical field】

[0 0 0 1]

The present invention relates to a catalyst layer ink and a method for producing a fuel cell.

[Background]

[0 0 0 2]

A solid polymer electrolyte type fuel cell has an electrolyte membrane, which is an ion conductive solid polymer membrane, between two electrodes. In this fuel cell, at one electrode, which is an anode, a reaction occurs in which hydrogen gas supplied as fuel is separated into protons and electrons. Proton moves to the other electrode via the electrolyte membrane, and electrons move to the other electrode via the external circuit. This movement of electrons generates current in the external circuit. On the other hand, the other electrode, which is a cathode, is supplied with oxygen gas, and protons that have moved from the electrolyte membrane and electrons that have moved from the external circuit react with oxygen gas to produce water.

[0 0 0 3]

Each electrode is provided with a catalyst layer in which a reaction of hydrogen gas or oxygen gas occurs. In the catalyst layer, catalyst particles such as platinum are supported by a carrier having pores such as mesoporous carbon. In order to enhance the catalytic action, the catalyst particles are usually covered with an electrolyte similar to the electrolyte membrane. The electrolyte used in such a catalyst layer is hereinafter referred to as an ionomer.

[0 0 0 4]

In general, since the particle diameter of the catalyst particles is smaller than the inner diameter of the pores of the carrier, the catalyst particles are supported not only on the outer surface of the carrier but also inside the pores. Therefore, when the catalyst particles inside the pores are also coated with the ionomer, the catalyst utilization rate is improved (see, for example, Patent Document 1).

[Prior art documents]

[Patent Literature]

[0 0 0 5]

[Patent Document 1] Japanese Patent Application Laid-Open No. 2 0 1 7-1 2 6 5 1 4

Summary of the Invention

[Problems to be solved by the invention]

[0 0 0 6]

The ionomer generally has an acidic functional group with a polymer having a repeating structure as a main chain. For example, naphthion ^ 3 ^ 011 (registered trademark), which is one of typical ionomers, has a polytetrafluoroethylene unit as a main chain and a perfluoroethersulfonic acid unit as a side chain.

[0 0 0 7]

Ionomer is easy to crystallize because the polymer of the main chain has a repeating structure. When an ionomer, a catalyst and a carrier are mixed with a hydrophilic solvent such as water or alcohol to prepare an ink for a catalyst layer, molecules are aggregated around the crystallized portion in each ionomer, and an acidic functional group is formed. Colloids arranged on the outside tend to be formed. As a result, it becomes difficult for the ionomer to penetrate into the pores of the support. In the catalyst layer formed using such a catalyst layer ink, the catalyst particles in the pores are not easily covered with the ionomer, and the catalyst utilization rate is lowered.

[0 0 0 8]

An object of the present invention is to provide a catalyst layer ink capable of forming a catalyst layer in which an ionomer is present in the pores of a carrier.

[Means for Solving the Problems]

[0 0 0 9]

The method for producing the ink for a catalyst layer according to the present invention is a method for producing an ink for a catalyst layer containing an ionomer, a catalyst, a carrier having pores, and a solvent, wherein the ionomer in the ink for the catalyst layer comprises A polymer having an acidic functional group or a precursor thereof, and the ionomer 〇 2019/224729 卩（： 17132019/054212

2

Mixing a material with the catalyst, the carrier and the solvent to obtain a mixture; and reacting the material in the mixture to produce the ionomer, thereby obtaining the catalyst layer ink; The manufacturing method of the ink for catalyst layers containing,.

[0 0 1 0]

The method for producing a fuel cell according to the present invention is a method for producing a fuel cell having catalyst layers on both sides of an electrolyte membrane, and the step of preparing an ink for a catalyst layer containing an ionomer, a catalyst, a carrier having pores, and a solvent And applying the catalyst layer ink to both surfaces of the electrolyte membrane to form the catalyst layer, wherein the ionomer in the catalyst layer ink has an acidic functional group or a precursor thereof. The step of preparing the ink for the catalyst layer is a step of mixing the ionomer material with the catalyst, the carrier and the solvent to obtain a mixture, and reacting the material in the mixture. Producing the ink for the catalyst layer by producing the ionomer.

【The invention's effect】

【0 0 1 1】

According to the present invention, it is possible to provide a catalyst layer ink capable of forming a catalyst layer in which an ionomer is present in the pores of the carrier.

[Brief description of the drawings]

[0 0 1 2]

FIG. 1 is a cross-sectional view showing a configuration of a fuel cell according to an embodiment.

FIG. 2 is a cross-sectional view showing an example of a carrier in which catalyst particles in the outer surface and pores are coated with an ionomer.

FIG. 3 is a cross-sectional view showing an example of a carrier in which only catalyst particles on the outer surface are coated with an ionomer.

BEST MODE FOR CARRYING OUT THE INVENTION

[0 0 1 3]

The production method of the present invention is a method for producing an ink for a catalyst layer and a fuel cell used for forming a catalyst layer of a fuel cell.

Hereinafter, embodiments of a catalyst layer ink and a fuel cell manufacturing method of the present invention will be described with reference to the drawings. The configuration described below is an example (representative example) as an embodiment of the present invention, and the present invention is not limited to the configuration described below.

[0 0 1 4]

(Fuel cell)

The fuel cell produced by the production method of the present invention may be a fuel cell having a single cell structure or a fuel cell having a stack structure.

Figure 1 shows an example of the configuration of a fuel cell, the basic unit of a fuel cell.

[0 0 1 5]

A fuel cell 10 shown in FIG. 1 is a solid polymer electrolyte fuel cell that generates electricity by receiving supply of hydrogen gas and oxygen gas. As shown in FIG. 1, the fuel cell 10 has two separators 3 and a membrane electrode assembly 4 provided between the two separators 3. The separator 3 has a flow path for flowing the gas supplied to the fuel cell 10 to the membrane electrode assembly 4. When the fuel battery cell 10 has a stack structure, the separator 3 electrically connects adjacent cells. As shown in FIG. 1, the membrane / electrode assembly 4 includes an electrolyte membrane 1 and two electrodes 2.

【0 0 1 6】

The electrolyte membrane 1 is a proton-donating solid polymer electrolyte membrane. For the electrolyte membrane 1, an electrolyte similar to the electrolyte that can be used in the electrode 2 described later can be used.

[0 0 1 7]

The two electrodes 2 are provided on both surfaces of the electrolyte membrane 1 respectively. One electrode 2 is an anode and is also called a fuel electrode. The other electrode 2 is a cathode and is also called an air electrode. In the electrode 2 which is an anode, a reaction occurs in which electrons (61) and protons (H ⁺ ) are generated from the hydrogen gas (H ₂ ) supplied via the separator 3. The electrons are sent to the cathode via an external circuit. 〇 2019/224729 卩（： 17132019/054212

Three

Move to a certain electrode 2. This movement of electrons generates a current in the external circuit. The proton moves through the electrolyte membrane 1 to the electrode 2 which is a cathode. In the electrode 2 which is a cathode, oxygen gas (0 ₂ ) is supplied via the separator 3, and oxygen ions (0 ² ) are generated by electrons moving from the external circuit. Oxygen ions combine with the proton (2 H +) that has migrated from the electrolyte membrane 1 to become water (H ₂ 0).

【0 0 1 8】

As shown in FIG. 1, each electrode 2 has a catalyst layer 2 1 and a gas diffusion layer 2 2. The gas diffusion layer 22 can be provided as necessary for the purpose of uniformly diffusing the hydrogen gas or oxygen gas supplied to each electrode 2 to the electrode 2. As the gas diffusion layer 22, for example, a porous fiber sheet having conductivity, gas permeability and gas diffusibility such as carbon fiber, a porous metal plate such as foam metal, and expanded metal is used. be able to.

[0 0 1 9]

(Catalyst layer)

The catalyst layer 2 1 is provided adjacent to the electrolyte membrane 1. The catalyst layer 21 includes a catalyst, a support, and an ionomer, and promotes the above-described reaction of hydrogen gas and oxygen gas by the catalyst. In the catalyst layer 21, a particulate catalyst is supported on a carrier, and the carrier and the catalyst are covered with an ionomer. The support and catalyst should be at least partially coated with ionomer, but from the viewpoint of improving the catalyst utilization rate, the larger the coated region, the better. From the viewpoint of increasing the reactivity with the gas, it is preferable that the ionomer layer covering the catalyst is thin.

[0 0 2 0]

(Catalyst)

The catalyst is not particularly limited as long as it has a catalytic action of hydrogen gas or oxygen gas. For example, platinum (Pt), ruthenium (Ru), iridium (Ir), rhodium (Rh) , Palladium (P d), osmium (O s), tungsten (W), lead (P b), iron (F e), chromium (C r), cobalt (C o), nickel (N i) Metals such as manganese (Mn), vanadium (V), molybdenum (Mo), gallium (Ga) and aluminum (A1), mixtures of these metals, and alloys. Of these, platinum, platinum-containing mixtures or alloys are preferred from the viewpoint of improving catalytic activity, poisoning resistance to carbon monoxide, heat resistance, and the like. When the catalyst is made of an alloy, the composition of the alloy depends on the type of metal to be alloyed. For example, the platinum content is 30 to 90 atomic%, and the other metal content is 10 to It can be 70 atomic%.

[00 2 1]

The average particle diameter of the catalyst is not particularly limited, but is preferably 1 to 30 nm, and more preferably 1 to 2 nm, from the viewpoint of improving the catalyst utilization rate and the supportability on the carrier.

The average particle diameter of the catalyst can be determined as the crystallite diameter determined from the half-value width of the diffraction peak of the catalyst particles in X-ray diffraction. The average particle diameter of the catalyst is the average value of the particle diameters of n catalyst particles observed with a transmission electron microscope (TEM) or a scanning electron microscope (SEM). You can also ask for it. For example, n can be 2 00 to 3 0 0.

[0 0 2 2]

(Carrier)

As the carrier, a conductive porous metal compound having pores can be used. An example of the porous metal compound is mesoporous carbon. As mesoporous carbon, for example, carbon black such as Ketchen Black (registered trademark), acetylene black, Vulcan (registered trademark), etc., and multi-layer graph entite are laminated to create mesoporous. Examples thereof include carbon having a formed structure. Examples of porous metal compounds include Pt black, Pd black, Pt metal deposited in fractal form, Ti, Zr, Nb, Mo, Hf, Examples thereof include oxides such as Ta and W, nitrides, carbides, oxynitrides, and carbonitrides. Of these, mesoporosca-bon is preferred from the viewpoint of good dispersibility, a large surface area, and low particle growth at high temperatures even when the amount of catalyst supported is large. 〇 2019/224729 卩（： 17132019/054212

Four

[0 0 2 3]

The average particle size of the carrier is not particularly limited, but is preferably from 10 to 100 nm from the viewpoint of improving the supportability of the catalyst particles.

The average particle size of the support can be determined by TEM or SEM in the same manner as the average particle size of the catalyst.

[0 0 2 4]

The average pore diameter of the pores of the carrier is not particularly limited, but is preferably 2 to 20 nm from the viewpoint of supporting the catalyst particles in the pores.

[0 0 2 5]

BET specific surface area of the support, from the viewpoint of carrying many catalyst particles, 5 0 m ² / g or more is good Mashiku, 5 0 0 m ² / g or more Ri preferably yo, is 7 0 0 m ² / g or more It is even better. Hand, BET specific surface area of the support, from the viewpoint of uniformly support the catalyst particles is preferably 1 5 0 0 m ² / g hereinafter, 1 3 0 0m ² / g is Ri preferably yo less, 1 0 0 0 m ² / g or less is even more preferable. Therefore, BET specific surface area of the support is preferably ^{5 0~ 1 5 0 0 m 2} / g, 5 0 0~ 1 3 0 0 m 2 / g Gayo Ri preferred lay, 7 0 0~ 1 0 0 0 m ² / g is more preferable. The BET specific surface area of the carrier is measured by a nitrogen adsorption method.

[0 0 2 6]

The mass of the catalyst supported on the carrier can be usually 1 to 99% by mass with respect to the total mass (100% by mass) of the catalyst and the carrier, which improves the catalytic activity and the supportability. From the viewpoint, 10 to 90% by mass is preferable, and 20 to 80% by mass is more preferable.

[0 0 2 7]

(Ionomer)

The ionomer is a proton-donating solid polymer electrolyte used in the catalyst layer 21. The ionomer has an acidic functional group with a polymer having a repeating structure as a main chain. The acidic functional group is not particularly limited as long as it is an acidic functional group, and examples thereof include a sulfonic acid group, a phosphoric acid group, and a carboxylic acid group. Among them, from the viewpoint of proton conductivity, Sulfonic acid groups are preferred. The mechanism of proton conduction by ionomers is that a hydrophilic core is formed by an acidic functional group, and a network of clusters in which water molecules are localized is formed in the core. Proton moving model has been proposed

[0 0 2 8]

Examples of the ionomer that can be used in the catalyst layer 21 include ion-exchangeable polymers such as a fluorine-based polymer and a hydrocarbon-based polymer having an acidic functional group. The ionomer used in the catalyst layer 21 may be the same type as the electrolyte used in the electrolyte membrane 1 or may be a different type.

[0 0 2 9]

Examples of the fluorine-based polymer having an acidic functional group include perfluorosulfonic acid polymer. The perfluorosulfonic acid polymer has a polytetrafluoroethylene (PTFE) unit and a perfluorosulfonic acid unit. A commercially available product can also be used as the perfluorosulfonic acid polymer. Examples of commercial products that can be used include Nafion (registered trademark, manufactured by DuPont), Aquivion (registered trademark, manufactured by Solvay), Flemion (FIemion: registered trademark, manufactured by Asahi Glass), Ash Plex (Aciplex: registered trademark, manufactured by Asahi Kasei Corporation).

[0 0 3 0]

The following are exemplary compounds (1) to (3) of the perfluorosulfonic acid polymer, but are not limited thereto. Exemplary compounds (1) and (2) are naphthion (registered trademark) and aqua ion (registered trademark), respectively. Illustrative compound (3) is an ionomer proposed by 3M Company.

【0 0 3 1】

[Chemical 1] 〇 2019/224729 卩（： 17132019/054212

Five

⑴

⑵

[0 0 3 2]

Examples of the hydrocarbon polymer having an acidic functional group include an aromatic polymer and an aliphatic polymer having an acidic functional group.

[0 0 3 3]

Aromatic polymers with acidic functional groups include, for example, sulfonated polyetheretherketones (£££! <;), Sulfonated polyethersulfones (3 £ 3), sulfonated polyphenylsulfones.

Sulfonated polyimide, sulfonated polyetherimide, sulfonated polysulfone, sulfonated polystyrene and the like.

[0 0 3 4]

The following are exemplary compounds (11) to (13) of an aromatic polymer having an acidic functional group, but are not limited thereto. Exemplary Compound (11) is £££ X, Exemplary Compound (12) is £££, Exemplary Compound (13) is a sulfonated polyetherimide.

[Chemical 2]

〇 2019/224729 卩 (： 17132019/054212

6

(11)

[0 0 3 5]

Examples of the aliphatic polymer having an acidic functional group include polyvinyl sulfonic acid and polyvinyl phosphonic acid.

[0 0 3 6]

The ion exchange capacity (IEC) of the ionomer is preferably 0.6 meq / g or more, more preferably 0.9 meq / g or more from the viewpoint of improving the proton conductivity. 1.2 meq / g or more is more preferable. The ion exchange capacity of the ionomer is preferably 3 meq / g or less, more preferably 2.5 meq / g or less, and 2 meq / g or less from the viewpoint of dimensional stability during water supply. Further preferred. Therefore, the ion exchange capacity of the ionomer is preferably 0.6 to 3 meq / g, more preferably 0.9 to 2.5 meq / g,

More preferred is 1-2 to 2 meq / g.

[0 0 3 7]

When the support is mesoporous carbon, the mass ratio (I / C) of the support (C) to the ionomer (I) is preferably 0.1 or more from the viewpoint of increasing ionic conductivity. Preferably it is 0.2 or more, more preferably 0.3 or more. Meanwhile, mass ratio (1 /

C) is preferably 2 or less, more preferably 1.5 or less, and even more preferably 1.1 or less, from the viewpoint of increasing the catalytic activity by suppressing the thickness of the ionomer covering the catalyst. It is. Accordingly, the mass ratio is preferably 0.1 to 2, more preferably 0.2 to 1.5, and still more preferably 0.3 to 1.1.

[0 0 3 8]

The thickness of the catalyst layer 21 is not particularly limited. However, from the viewpoint of the catalyst performance of the catalyst layer 21 and the formability of the catalyst layer 21, the thickness is preferably 0.1 _/ im or more. or more preferable towards good, in terms of gas diffusibility, the catalyst layer 2 1 of the thickness is preferably the this or less _{5 0 / i m, 2 0} "m preferably Ri in which this Togayo less. Therefore, the thickness of the catalyst layer 21 is preferably 0.1 to 50 _/ im, more preferably 1 to 20 "m.

[0 0 3 9] 〇 2019/224729 卩（： 17132019/054212

7

The catalyst layer 21 of the fuel cell 10 described above includes a step of preparing catalyst layer ink and a step of forming the catalyst layer 21 by applying the prepared catalyst layer ink on both surfaces of the electrolyte membrane 1. And can be formed through

[0 0 4 0]

(Method for producing ink for catalyst layer)

In the step of preparing the catalyst layer ink, an ionomer is formed in the catalyst layer ink including a carrier having a pore, a catalyst, and a solvent. In this embodiment, the step of preparing the ink for the catalyst layer includes the step of mixing the ionomer material with the catalyst, the carrier and the solvent to obtain a mixture, and reacting the material in the mixture to produce the ionomer. And obtaining a catalyst layer ink.

[0 0 4 1]

(Step of obtaining a mixture)

As the solvent for the catalyst layer ink, a polar proton solvent such as water or alcohol can be usually used. For example, when mesoporous carbon is used as a carrier and platinum is used as a catalyst, mesoporous carbon is dispersed in pure water, and nitric acid is added to this dispersion. Furthermore, after adding an aqueous dinitrodiamine platinum salt solution, it is reduced by adding ethanol and heating. As a result, a dispersion of mesoporous carbon carrying platinum particles on the outer surface and inside the pores can be obtained. The mixture is obtained by mixing the ionomer material with the obtained dispersion.

[0 0 4 2]

(Step of generating ionomer)

In the resulting mixture, the ionomer material is reacted to form an ionomer. The ionomer material may be mixed and reacted several times.

In ionomers, polymers are hydrophobic and acidic functional groups are hydrophilic. Therefore, ionomer molecules aggregate in a hydrophilic solvent such as water, alcohol, etc., and the hydrophilic portion is arranged around the hydrophobic portion in which the polymer of each ionomer molecule is oriented and crystallized, for example, the diameter 10 11 1X1 A relatively large colloid tends to be formed. Due to the large size of the colloid, it is difficult for the ionomer to penetrate into the pores of the support in a solvent, and it tends to cover only the outer surface of the support.

[0 0 4 3]

In contrast, the ionomer material is not a polymer but a monomer and is smaller in size than the inner diameter of the pores. Therefore, an ionomer can be produced inside the pores of the carrier by allowing the material to react after the material has entered the pores of the carrier in the catalyst layer ink. That is, the ionomer in the ink for the catalyst layer exists not only on the outer surface of the carrier but also inside the pores. In the catalyst layer formed using such a catalyst layer ink, not only the outer surface of the carrier but also the catalyst supported in the pores are covered with the ionomer. In addition to the catalyst supported on the outer surface of the carrier, the catalytic action of the catalyst inside the pores can be obtained, so the catalyst utilization rate is improved.

[0 0 4 4]

The ionomer in the catalyst layer ink may be a polymer having an acidic functional group that can be used as an electrolyte, or may be a polymer having a precursor of an acidic functional group. Examples of precursors include halogenated acidic functional groups such as 1 £ 0 ₂ F and 1 £ 0 ₂ 0 1, and acidic functional groups such as 1 £ 0 3 X 3 and-£ 0 3 (NH ₄ ). Examples thereof include a protecting group in which the group is protected with a metal or the like. When the ionomer is a polymer having a precursor of an acidic functional group, the ionomer can be used as an electrolyte by performing a protonation such as saponification to convert it into an acidic functional group. Is possible.

[0 0 4 5]

When the ionomer is a perfluorosulfonic acid polymer, for example, a polymer having a repeating structure derived from tetrafluoroethylene, that is, polytetrafluoroethylene, is obtained by polymerization reaction using tetrafluoroethylene as a monomer. Produce ethylene 〇 2019/224729 卩（： 17132019/054212

8

To do. Further, a perfluorosulfonic acid precursor is mixed and reacted with this polytetrafluoroethylene to produce a perfluorosulfonic acid polymer having a polytetrafluoroethylene unit and a unit of perfluorosulfonic acid precursor. To do. Note that the reaction process of the perfluorosulfonic acid polymer is not limited to this, and it may be generated by an optimal reaction process for the target perfluorosulfonic acid polymer.

[0 0 4 6]

When the ionomer is an aromatic polymer having an acidic functional group, it has a polymerization reaction of an aromatic vinyl monomer having an acidic functional group or a precursor thereof, and has an aromatic vinyl monomer and an acidic functional group or a precursor thereof. Aromatic polymer with acidic functional group or precursor is generated in the ink for catalyst layer by polymerization reaction of vinyl monomer, polymerization reaction of vinyl monomer and acidic functional group or precursor with aromatic vinyl monomer. To do. The aromatic vinyl monomer that can be used can be appropriately selected according to the design of the target aromatic polymer. For example, styrene, methylstyrene, benzophenone, 4, 4'-difluorobenzophenone, 4

, 4 ^/ —dichlorodiphenyl sulfone, hydroquinone and the like. The reaction process is not limited to the above. For example, is a polymerization reaction of 4,4'-difluorobenzophenone and hydroquinone in the presence of potassium carbonate? , And then mixed with sulfuric acid and stirred at a predetermined temperature for a predetermined time to cause a sulfonation reaction of X.

£ X can be generated.

[0 0 4 7]

When the ionomer is an aliphatic polymer having an acidic functional group, a polymerization reaction of an aliphatic vinyl monomer having an acidic functional group or a precursor thereof, an aliphatic vinyl monomer having an acidic functional group or a precursor thereof, and An aliphatic polymer having an acidic functional group or a precursor thereof is generated in the catalyst layer ink by a polymerization reaction with an aliphatic vinyl monomer. The aliphatic vinyl monomer that can be used can be appropriately selected according to the design of the target aliphatic polymer. Examples thereof include acrylic vinyl monomers such as acrylonitrile and olefins such as ethylene and propylene. It is done.

[0 0 4 8]

A polymerization initiator can be used for the polymerization reaction. Examples of usable polymerization initiators include persulfates such as potassium persulfate and ammonium persulfate, 4,4'-azobis 4-cyanovaleric acid and its salts, 2,2'-azobis (2-amidinopropane) salts, and the like. And azo compounds and peroxide compounds.

[0 0 4 9]

In the ink for the catalyst layer produced as described above, since the ionomer in the ink for the catalyst layer is generated inside the pores of the support, the ionomer is present not only on the outer surface of the carrier but also inside the pores. be able to. By forming a catalyst layer using such a catalyst layer ink, a catalyst layer in which not only the outer surface of the carrier but also catalyst particles located in the pores are coated with an ionomer can be obtained.

[0 0 5 0]

FIG. 2 shows an example of a carrier in which an ionomer has penetrated into the pores.

As shown in FIG. 2, the catalyst 11 is supported on the outer surface and pores of the support 12. The ionomer 13 is present not only on the outer surface of the support 12 but also inside the pores, and covers the support 12 and the catalyst 11. The ionomer 13 can conduct ions to the catalyst 11 supported not only on the outer surface but also in the pores, thereby improving the catalyst utilization rate.

【0 0 5 1】

FIG. 3 shows an example of a carrier in which only the outer surface is coated with an ionomer.

As shown in FIG. 3, the ionomer 13 whose size is larger than the pores of the carrier 12 cannot penetrate into the pores of the carrier 12 and ion conduction to the catalyst 11 supported in the pores. The rate goes down. The catalytic action is due to the catalyst 1 1 existing on the outer surface of the carrier 12 coated with the ionomer 13, and the catalyst utilization rate is reduced compared to the example shown in FIG.

[0 0 5 2] 〇 2019/224729 卩（： 17132019/054212

9

(Fuel cell manufacturing method)

The fuel cell 10 described above can be manufactured through the steps of preparing a catalyst layer ink and applying the catalyst layer ink to both surfaces of the electrolyte membrane 1 to form the catalyst layer 21. In the step of preparing the catalyst layer ink, as described above, an ionomer is generated in the catalyst layer ink.

[0 0 5 3]

Next, the gas diffusion layer 22 is formed by sandwiching the formed catalyst layer 21 between carbon fiber sheets or the like and thermocompression bonding. Thereby, the membrane electrode assembly 4 of the electrolyte membrane 1 and the electrode 2 is obtained. By sandwiching the surface of each membrane electrode assembly 4 on the side of each electrode 2 between two separators 3, a fuel cell 10 can be obtained.

[0 0 5 4]

As mentioned above, although preferable embodiment of this invention was described, this invention is not limited to these embodiment, A various deformation | transformation and change are possible within the scope of this invention.

[Explanation of symbols]

[0 0 5 5]

1... Fuel cell, 4 .. Membrane electrode assembly, 1... Electrolyte membrane, 2... Electrode, 2

1 catalyst layer, 2 2 gas diffusion layer, 3 separator

Claims

〇 2019/224729 卩（： 17132019/054212 10 [Document Name] Claim

[Claim 1]

A method for producing an ink for a catalyst layer comprising an ionomer, a catalyst, a carrier having pores, and a solvent, comprising:

The ionomer in the ink for the catalyst layer is a polymer having an acidic functional group or a precursor thereof;

Mixing the ionomer material with the catalyst, the support and the solvent to obtain a mixture;

Reacting the material in the mixture to produce the ionomer, thereby obtaining the catalyst layer ink;

The manufacturing method of the ink for catalyst layers containing this.

[Claim 2]

The ionomer in the catalyst layer ink is a perfluorosulfonic acid polymer having a polymer unit having a repeating structure derived from tetrafluoroethylene, and a unit of perfluorosulfonic acid or a precursor thereof. ,

The method for producing the ink for a catalyst layer according to claim 1.

[Claim 3]

The ionomer in the ink for the catalyst layer is a hydrocarbon-based polymer having an acidic functional group or a precursor thereof.

The method for producing the ink for a catalyst layer according to claim 1.

[Claim 4]

The method for producing an ink for a catalyst layer according to any one of claims 1 to 3, wherein the ionomer in the ink for the catalyst layer is present in pores of the carrier.

[Claim 5]

A method for producing a fuel cell having a catalyst layer (2 1) on both sides of an electrolyte membrane (1), comprising the steps of preparing an ink for a catalyst layer comprising an ionomer, a catalyst, a carrier having pores, and a solvent;

Applying the catalyst layer ink on both surfaces of the electrolyte membrane to form the catalyst layer; and

The step of preparing the ink for the catalyst layer includes:

A method for producing a fuel cell comprising: