JP6988544B2 - Manufacturing method of catalyst layer for fuel cell - Google Patents

Description

The present invention relates to a method for manufacturing a catalyst layer for a fuel cell.

A solid polymer fuel cell is attracting attention as an energy source as a fuel cell that generates electricity by an electrochemical reaction between a fuel gas and an oxidant gas. In a polymer electrolyte fuel cell, a membrane electrode assembly (“fuel electrode”) in which electrodes (air electrode and fuel electrode) made of a catalyst layer are bonded to both sides of a solid polymer electrolyte membrane, which is an electrolyte membrane, respectively. -Solid polymer electrolyte membrane-air electrode ") (also called MEA) is used.

Each electrode is formed from a catalyst layer, and the catalyst layer is a layer for causing an electrode reaction by an electrode catalyst contained in the catalyst layer. Since a three-phase interface in which three phases of an electrolyte, a catalyst, and a reaction gas coexist is required for advancing the electrode reaction, the catalyst layer is generally composed of a layer containing a catalyst and an electrolyte.

Various studies have been conducted on each component of such a polymer electrolyte fuel cell to improve the performance of the fuel cell.

For example, the electrolyte membrane for a polymer electrolyte fuel cell, Patent Document 1 is composed of a cation exchange membrane made of a polymer compound having a sulfonic acid group, -SO 3 in the cation exchange membrane _- 0 group. An electrolyte membrane containing one or more selected from the group consisting of 3 mol% or more of cerium ions and manganese ions and a sparingly soluble cerium compound is disclosed. In the electrolyte membrane, the electrolyte membrane is not deteriorated in power generation characteristics. By containing the sparingly soluble cerium compound in the electrolyte membrane in which a part of the sulfonic acid group of the above is ion-exchanged with cerium ion or manganese ion, the long-term durability of the electrolyte membrane can be realized.

Patent Document 2 is composed of an ion exchange membrane composed of a polymer compound having a CH bond of 10% or more with respect to the total number of chemical bonds and having an acidic group, and is selected from the group consisting of a cerium atom and a manganese atom. Disclosed is an electrolyte membrane for a solid polymer fuel cell containing one or more of the above, and in the electrolyte membrane, deterioration of the electrolyte membrane is caused by containing a cerium atom or a manganese atom in an inexpensive hydrocarbon-based electrolyte. It is said that it can suppress.

Further, regarding the catalyst layer constituting each electrode, Patent Document 3 describes on the surface a substituted electrolyte in which at least a part of the counter ion of the ionic conductive group is substituted with a metal ion, and a compound containing a six-membered heterocyclic portion on the surface. A catalyst layer containing adsorbed electrode catalyst particles is disclosed, and in the catalyst layer, an ionic conductive group ^{is substituted by replacing the proton (H +} ) of the ionic conductive group of the electrolyte with a metal ion. It is said that it is possible to prevent the bond between the compound and the compound containing the 6-membered heterocyclic moiety and suppress the amount of the compound containing the 6-membered heterocyclic moiety.

In the membrane electrode assembly of a polymer electrolyte fuel cell, each electrode (catalyst layer) is formed by applying catalyst ink to the surface of the film and drying it. The catalyst ink preferably exists in a stable state at the time of coating, but the catalyst ink has a problem of foaming.

To solve this problem, for example, Patent Document 4 describes a storage tank for accommodating a liquid to be agitated, a rotary drive device for rotationally driving a rotary shaft in the storage tank, and a U-shape provided at the lower end of the rotary shaft. The bottom wing is provided with a paddle wing provided on the rotation axis so as to be located inside the U-shaped bottom wing, and the paddle wing has a drain plate for forming a shear flow. The stirring device is disclosed, and in the stirring device, the bottom blade and the paddle blade can be rotated at a low speed by the shear flow formed by the liquid drain plate of the paddle blade, and the generation of turbulent flow and air bubbles can be suppressed. That is.

Patent Document 5 unifies an ink supply port into which ink flows, a manifold that allows ink to expand and contract in the width direction, and an ink passage that allows ink to pass through slits at predetermined intervals and coalesces ink bubbles. Disclosed is an ink defoaming device composed of a bubble collecting manifold that raises the collected bubbles by buoyancy, a bubble removing mechanism that raises and removes the collected bubbles, and an ink outlet that discharges ink. The ink defoaming device can efficiently and continuously remove air bubbles in the ink.

Patent Document 6 is a method for producing an ink composition for forming a catalyst layer of a fuel cell, in which a gas mixed with alcohol is brought into contact with the ink and pressurized through the gas while being in the middle of the liquid state of the ink composition. It discloses a method for producing an ink composition, which comprises a step of filtering an article, in which the alcohol is concentrated at the interface between the gas and the ink inside the foam so that the foam can be made with a small amount of alcohol. It is said that the occurrence can be suppressed.

Japanese Unexamined Patent Publication No. 2006-260811 Japanese Unexamined Patent Publication No. 2007-188706 Japanese Unexamined Patent Publication No. 2008-47401 Japanese Unexamined Patent Publication No. 2015-213886 Japanese Unexamined Patent Publication No. 2016-140847 JP-A-2017-201583

The catalyst ink contains a catalyst powder, ^{an electrolyte having proton (H +} ) conductivity, and a solvent for dispersing the catalyst powder and the electrolyte. The physical characteristics of the catalyst ink greatly affect the subsequent transferability, structural defects, crackability, and the like. Therefore, the solvent of the catalyst ink that can affect the physical properties of the catalyst ink is determined in consideration of various factors. Since a mixed solvent of water and alcohol is usually used as the solvent of the catalyst ink, the mixing ratio of the mixed solvent of the catalyst ink (also referred to as “solvent ratio” in the present specification and the like) is important.

The foaming property of the catalyst ink, which is one of the physical properties of the catalyst ink, is also affected by the solvent ratio. The bubbles present in the catalyst ink may subsequently cause defects on the catalyst layer coated surface. Defects on the coated surface of the catalyst layer accelerate the deterioration of the catalyst layer. Therefore, foaming property is also a factor to be considered when determining the solvent ratio.

The foaming property of the catalyst ink is affected by the electrolyte, for example, ionomer, as well as the solvent ratio. The bubbles generated in the catalyst ink can be stabilized by the electrolyte. The electrolyte has a hydrophilic part and a hydrophobic part, and can form micelles centered on a gas to stabilize bubbles (air bubbles).

FIG. 4 shows a schematic diagram of an example of the molecular arrangement of the electrolyte when the bubbles are stabilized. According to FIG. 4, the bubble 3 rises near the interface between the liquid in which the electrolyte 1 is present and the air. The electrolyte 1 existing near the interface between the liquid and the air orients the hydrophobic portion toward the gas portion inside the foam 3 by coming into contact with the foam 3. The bubbles 3 are stabilized by stabilizing and orienting the molecules of the electrolyte 1 on the interface of the bubbles 3.

In order to remove the bubbles generated in this way, it is necessary to break the molecular arrangement of the ionomer forming the micelle.

However, in the mechanical defoaming method using an apparatus such as Patent Documents 4 and 5, it is difficult to change the apparatus configuration every time the conditions are changed.

Further, in Patent Document 6, alcohol is used as an antifoaming agent, and further addition of alcohol can significantly change the solvent ratio. Normally, the amount of alcohol required as an antifoaming agent is an amount that can affect the application of the catalyst ink and the transfer of the catalyst layer, so it is difficult to adjust the solvent ratio in consideration of the amount of the alcohol. Is.

Therefore, it is an object of the present invention to provide a method for preparing a catalyst ink that does not easily foam and producing a catalyst layer for a fuel cell with reduced defects from the catalyst ink.

As a result of various studies on means for solving the above-mentioned problems, the present inventor binds to the hydrophilic part of an ionomer molecule in a suspension containing a catalyst, an electrolyte, and a solvent in the production of a catalyst layer for a fuel cell. We have found that the generation of bubbles in the catalyst ink can be suppressed by adding metal ions that are easy to easily form, and as a result, the generation of defects on the coated surface of the catalyst layer can be suppressed, and the present invention has been completed.

That is, the gist of the present invention is as follows.
(1) (i) A step of mixing a catalyst, an electrolyte, and a solvent to prepare a suspension.
(Ii) A step of adding metal ions to the suspension prepared in the steps of (i) to prepare a catalyst ink, and a step of preparing the catalyst ink.
(Iii) A method for manufacturing a fuel cell catalyst layer, which comprises a step of preparing a fuel cell catalyst layer from the catalyst ink prepared in the steps (ii).

INDUSTRIAL APPLICABILITY According to the present invention, a catalyst ink that does not easily foam can be prepared, and a catalyst layer for a fuel cell with reduced defects can be produced from the catalyst ink.

An example of the defoaming mechanism according to the present invention is schematically shown. The flow which compared an example of the conventional method and the method by this invention in the preparation of a catalyst ink is shown. Shows the metal ion and the substitution ratio of the counter ion of the sulfonic acid groups of the electrolyte (H ⁺⁾ (sulfonic acid group replacement ratio), a relation between the O ₂ gas diffusion resistance R _tot and froth height. A schematic diagram of an example of the molecular arrangement of the electrolyte when the foam is stabilized is shown.

Hereinafter, preferred embodiments of the present invention will be described in detail.
In the present specification, the features of the present invention will be described with reference to the drawings as appropriate. The drawings exaggerate the dimensions and shapes of each part for clarity and do not accurately depict the actual dimensions and shapes. Therefore, the technical scope of the present invention is not limited to the dimensions and shapes of the parts shown in these drawings. The method for manufacturing the catalyst layer for a fuel cell of the present invention is not limited to the following embodiment, and various changes and improvements that can be made by those skilled in the art are made without departing from the gist of the present invention. It can be carried out in the form.

The present invention includes (i) a step of mixing a catalyst, an electrolyte, and a solvent, (ii) a step of adding metal ions to the suspension prepared in steps (i), and (iii) (ii). ) The present invention relates to a method for manufacturing a fuel cell catalyst layer, which includes a step of preparing a fuel cell catalyst layer from the catalyst ink prepared in the step of).

Each step (i) to (iii) will be described below.

(I) Step of mixing the catalyst, the electrolyte and the solvent In the step of (i) of the present invention, the catalyst, the electrolyte and the solvent are mixed to prepare a suspension.

Here, as the catalyst, a catalyst known in the art can be used, and for example, a metal-supported catalyst can be used, without limitation. In the metal-supported catalyst, the metal catalyst is supported on the carrier.

As the carrier, a carrier known in the art can be used, and for example, carbon black, carbon nanotubes, carbon materials such as carbon nanofibers, carbon compounds such as silicon carbide, and the like can be used. can.

The metal catalyst supported on the carrier reacts at the electrode of MEA. Air electrode (cathode): O ₂ + 4H ⁺ + 4e ⁻ → 2H ₂ O
Fuel electrode (anode): 2H ₂ → 4H ⁺ + 4e ⁻
The above is not limited as long as it exhibits a catalytic action, and a metal catalyst known in the art can be used. As the metal catalyst, for example, but not limited to, platinum, platinum alloys, palladium, rhodium, gold, silver, osmium, iridium and the like can be used. Examples of the platinum alloy include platinum and aluminum, chromium, manganese, iron, cobalt, nickel, gallium, zirconium, molybdenum, ruthenium, rhodium, palladium, vanadium, tungsten, renium, osmium, iridium, titanium and lead. There are alloys with at least one of them.

The amount of the metal catalyst is not limited, but is usually 10% by weight to 80% by weight based on the total weight of the metal-supported catalyst.

The amount of the metal-supported catalyst is not limited, but is usually 1% by weight to 40% by weight based on the total weight of the catalyst ink.

As the electrolyte, an electrolyte material known in the art can be used, for example, but not limited to, an ionomer, for example, a perfluorosulfonic acid resin material which is an ionomer known in the art, such as Nafion, or the like. Sulfated plastic electrolytes such as sulfonated polyether ketones, sulfonated polyether sulfones, sulfonated polyether ether sulfones, sulfonated polysulfones, sulfonated polysulfides, sulfonated polyphenylenes, sulfoalkylated polyether ether ketones, sulfoalkylated polys. Sulfonylated plastic electrolytes such as ether sulfone, sulfoalkylated polyether ether sulfone, sulfoalkylated polysulfone, sulfoalkylated polysulfide, and sulfoalkylated polyphenylene can be used.

The amount of electrolyte is not limited, but is usually 0.1% by weight to 50% by weight based on the total weight of the catalyst ink.

As the solvent, a catalyst known in the art can be used, and water, alcohols such as fatty alcohols such as methanol, ethanol, 1-propanol and 2-propanol, polyhydric alcohols such as propylene glycol and the like can be used. And their mixed solvent can be mentioned.

When a mixed solvent is used as the solvent, the solvent ratio does not need to consider the foaming property of the catalyst ink as described below, and therefore cannot be used in consideration of the foaming property of the catalyst ink in the past. But it may be usable. For example, in the case of a mixed solvent of water and ethanol, the solvent ratio (water: ethanol) is not limited, but is usually 1: 0.1 to 1:10.

In step (i) of the present invention, by preparing a suspension containing a catalyst, an electrolyte, and a solvent before adding the metal ion, the electrolyte can be blended into the catalyst in a soft state.

If the counterion of the electrolyte is replaced with a metal ion before the electrolyte is blended with the catalyst, the rigidity of the electrolyte replaced with the metal ion increases. Therefore, in the catalyst ink prepared by adding the solvent and the catalyst thereafter, the electrolyte substituted with the metal ion is hard to loosen and is hard to be familiar with the catalyst.

In the step (i) of the present invention, the addition order, addition temperature, mixing method, mixing time, etc. of each material are not limited, and the catalyst and the electrolyte are blended into the solvent and mixed so as to be homogeneous. For example, in step (i) of the present invention, the solvent is added to the reaction vessel at 5 ° C to 80 ° C, and then the catalyst and the electrolyte are added in order while stirring with a stirrer, and the electrolyte is dissolved in the solvent. , For example, may be mixed for 1 to 120 minutes until the suspension becomes homogeneous.

(Ii) Step of adding metal ions to the suspension prepared in step (i) In step (ii) of the present invention, metal ions are added to the suspension prepared in step (i). To prepare the catalyst ink.

The metal ion is water-soluble, does not interfere with its function as a contamination in the catalyst layer, and is exposed to an acidic environment having a pH of 0 to 5 and a low potential of about 0 to 1.0 V during power generation. However, it does not precipitate as a metal and does not damage the electrolyte membrane, and can exist as a metal ion.

The metal ion is not limited as long as it has the above-mentioned properties, but is, for example, an alkali metal such as sodium (Na), potassium (K), rubidium (Rb), magnesium (Mg), calcium (Ca), strontium (Sr). ), Alkaline earth metals such as barium (Ba), and ions such as lanthanoids such as strontium (Ce) and lanthanum (La). As the metal ion, cerium ion is preferable.

The addition of the metal ion is carried out by adding a metal, a metal salt, or a solution containing the metal ion, which will be present as a metal ion in the suspension prepared in step (i).

The metal is not limited as long as the metal ions generated in the suspension have the above-mentioned properties, but for example, alkali metals such as Na, K and Rb, and alkaline earth metals such as Mg, Ca, Sr and Ba. , Ce, La and other lanthanoids, and when they do not dissolve in the suspension, an oxidizing agent or a reducing agent can be added at the same time as long as the properties of the catalyst ink are not affected.

The metal salt is not limited as long as the metal ions generated in the suspension have the above-mentioned properties, but for example, alkali metals such as Na, K and Rb, and alkaline earths such as Mg, Ca, Sr and Ba. Salts such as metals, lanthanoids such as Ce and La, such as inorganic salts such as hydrochlorides, sulfates, nitrates, phosphates and the like, organic salts such as carboxylates and sulfonates and the like can be mentioned.

The solution containing the metal ion is not limited as long as the metal ion has the above-mentioned properties, and examples thereof include those prepared by dissolving the metal and the metal salt in a solvent of a suspension in advance, for example, in water. ..

The addition amount of the metal ions have low height of foaming in the catalyst ink, and is preferably set to O ₂ gas diffusion resistance is small in the catalyst layer, a pair of sulfonic acid groups of the metal ions and the electrolyte ions ( The replacement ratio with H ⁺ ) is usually adjusted to be 0.3% to 10%. The substitution ratio of the metal ion and the counterion (H ⁺ ) of the sulfonic acid group is almost proportional to the amount of the metal ion added.

^{The substitution ratio between the metal ion and the counterion (H +} ) of the sulfonic acid group of the electrolyte can be calculated, for example, as follows.

The fuel cell catalyst layer prepared in step (iii) is immersed in an acidic solution such as sulfuric acid, hydrochloric acid, nitric acid, etc. at 20 ° C to 30 ° C for 1 to 2 hours. By immersing in an acidic solution, the metal ion bonded to the sulfonic acid group of the electrolyte in the catalyst layer for the fuel cell ^{is replaced with H +} and dissolved in the acidic solution. Next, the metal ions dissolved in the acidic solution are analyzed and quantified by, for example, an ICP emission analyzer to calculate the substitution ratio between the ^{metal ions and the counter ion (H +) of the sulfonic acid group of the electrolyte.}

In step (ii), by adding metal ions to the suspension prepared in step (i), the metal ions are ^{replaced with the hydrophilic part of the electrolyte, that is, the counterion (H +} ) of the sulfonic acid group. Then, the molecular arrangement of the electrolyte in the micelle centered on the gas can be disrupted, and the bubbles in the catalyst ink can be removed. Therefore, since the catalyst ink does not generate bubbles, it is not necessary to prepare a device for defoaming.

FIG. 1 schematically shows an example of the defoaming mechanism according to the present invention. In FIG. 1, when the bubbles 3 generated in the suspension or the catalyst ink rise near the interface between the liquid and the air, the metal ion 2 added in the step (ii) causes the electrolyte for stabilization. Micelle formation by 1 is suppressed and disappears.

When the counterion of the electrolyte was replaced with a metal ion to uniformly disperse the metal ion before preparing the suspension in the step (i), the preparation was made by adding a solvent and a catalyst. With the catalytic ink, the molecular arrangement of the electrolyte in the micelle is stabilized. Therefore, the defoaming effect is small. Since the defoaming mechanism involves destabilizing micelles, it is preferable that the metal ions are present in the suspension to some extent non-uniformly. That is, by adding metal ions after preparing the suspension, the metal ions present to some extent in the suspension are ^{replaced with the hydrophilic part of the electrolyte, that is, the counterion (H +} ) of the sulfonic acid group. As a result, the molecular arrangement of the electrolyte in the micelle is destabilized and the defoaming effect is enhanced.

FIG. 2 shows a flow comparing an example of the conventional method and the method according to the present invention in the preparation of the catalyst ink. From FIG. 2, in the conventional method, the catalyst ink is prepared by mixing the catalyst, the electrolyte, and the solvent, but in the method according to the present invention, the catalyst, the electrolyte, and the solvent are first mixed and suspended. A liquid is prepared, and then metal ions are added to prepare a catalytic ink.

The defoaming effect according to the present invention is exhibited by adding metal ions to the suspension, and is not affected by the solvent ratio. In other words, the solvent ratio in the catalyst ink can be determined without considering the foaming property of the catalyst ink, which should be considered conventionally. Therefore, according to the present invention, the design map of the solvent ratio can be expanded.

(Iii) Step of preparing a fuel cell catalyst layer from the catalyst ink prepared in the steps (ii) In the step (iii) of the present invention, the fuel cell catalyst layer is prepared from the catalyst ink prepared in the step (ii). Prepare.

Here, the preparation of the catalyst layer for a fuel cell from the catalyst ink can be carried out by a method known in the art.

The step (iii) of the present invention can be carried out, for example, as follows.

The catalytic ink prepared in step (ii) can be peeled off by using a known spraying / adhering / coating method, for example, a method utilizing gravity, spraying force, or electrostatic force, for example, an applicator, for example, Teflon. It is applied on a sheet or the like to form a catalyst layer precursor for a fuel cell. The catalyst layer precursor for a fuel cell on a substrate is dried at room temperature to 80 ° C. for 30 minutes to 24 hours using a known drying method, for example, a blower dryer to remove volatile substances such as a solvent. It is removed to prepare a fuel cell catalyst layer, and the fuel cell catalyst layer is peeled off from the substrate to obtain a fuel cell catalyst layer.

Here, in the above, the catalyst layer for the fuel cell is obtained by spraying, adhering, and applying the catalyst ink for the fuel cell electrode on the substrate, and then drying and peeling off. However, the catalyst ink is a solid polymer electrolyte. It is also possible to prepare a state in which the catalyst layer for a fuel cell and the solid polymer electrolyte membrane are bonded by directly spraying / adhering / coating on the surface of a film such as a Nafion film and then drying.

The catalyst layer for a fuel cell is not limited, but usually has a layer thickness of 1 μm to 100 μm.

The catalyst layer for a fuel cell of the present invention can be used as an air electrode and / or a fuel electrode contained in the MEA of various electrochemical devices such as a polymer electrolyte fuel cell.

Further, using the catalyst layer for a fuel cell of the present invention, MEA can be prepared, for example, as follows.

The catalyst layer for a fuel cell of the present invention is used as an air electrode and a fuel electrode, and an air electrode is arranged on one surface and a fuel electrode is arranged on the other surface centering on a solid polymer electrolyte membrane. Get an aggregate. Here, the air electrode and the fuel electrode are prepared to be adapted to each electrode by changing the metal catalyst or the like used. The layer aggregates arranged like the air electrode-solid polyelectrolyte membrane-fuel electrode are crimped by hot pressing to obtain MEA.

The fuel cell finally manufactured using the catalyst layer for a fuel cell of the present invention can be used as various electrochemical devices such as a polymer electrolyte fuel cell.

Hereinafter, some examples of the present invention will be described, but the present invention is not intended to be limited to those shown in such examples.

1. 1. Production of catalyst layer In the following production method, the amount of metal ions added was changed to produce catalyst layers with different amounts of metal ions.

(I) Step to prepare a suspension by mixing a catalyst, an electrolyte and a solvent The catalyst, ionomer as an electrolyte and a solvent are mixed at 25 ° C. for 1 to 120 minutes to prepare a suspension. Prepared.

(Ii) Cerium ion (first nitrate) as a metal ion is added to the suspension prepared in step (i) to prepare the catalyst ink by adding metal ions to the suspension prepared in step (i). A cerium solution (manufactured by Taiyo Koko Co., Ltd.) was added and mixed at 25 ° C. for 1 to 120 minutes to prepare a catalyst ink. At that time, the foaming height at room temperature was measured.

(Iii) The catalyst ink prepared in the step (ii) of preparing the catalyst layer for a fuel cell from the catalyst ink prepared in the steps of (ii) is applied onto the PTFE as a base material at 25 ° C. , A catalyst layer precursor was formed. The catalyst layer precursor on the PTFE is dried at 80 ° C. for 60 minutes using an air furnace to remove volatile substances such as a solvent, prepare a catalyst layer, and peel the catalyst layer from the PTFE. By doing so, a catalyst layer was manufactured.

2. 2. Measurement of the substitution ratio of the metal ion in the catalyst layer and the counterion (H ^{+) of the sulfonic acid group of the electrolyte.} For each catalyst layer produced in the production of the catalyst layer, the substitution ratio (also referred to as "sulfonic acid group substitution ratio") between the ^{metal ion and the sulfonic acid group pair ion (H +) of the electrolyte was calculated by the following method.} ..

The catalyst layer was directly heated and incinerated, and the residue was dissolved in a strong acid to carry out ICP-MS. The number of sulfonic acid groups was quantified by the ion substitution method.

3. 3. Measurement of O ₂ gas diffusion resistance value R _tot of catalyst layer 1. For each catalyst layer produced in the production of the catalyst layer, the O ₂ gas diffusion resistance value R _tot was measured by the following method.

A catalyst layer, the relative humidity (RH): 30%, O 2 concentration: at 1% of conditions, using a potentiostat, the current - carried out voltage measurements, gas diffusion from the following equation from the obtained limiting current values The resistance value was calculated.
R _tot = 4 × F × P _O2 / (R × T × I _lim )
(In the formula, R _tot : gas diffusion resistance value, F: Faraday constant, _PO2 : oxygen partial pressure, R: gas constant, T: absolute temperature of cell temperature, _Ilim : limit current value.)

4. From the results obtained in Results 1 to 3, FIG. 3 _{shows the relationship between the sulfonic acid group substitution ratio of the metal ion, the O 2} gas diffusion resistance value R _tot, and the foaming height.

From FIG. 3, it was found that when the sulfonic acid group substitution ratio of the metal ion was 0.3% to 10% _{, both the O 2} gas diffusion resistance value R _tot and the foaming height became small.
By using a catalyst ink whose foaming height is lowered by adding metal ions, _{a catalyst layer having a small O 2} gas diffusion resistance value R _tot, that is, a catalyst layer in which the generation of defects is suppressed is manufactured. Was made.

1. 1. Electrolyte, 2. Metal ion, 3. foam

Claims (1)

(I) A step of mixing a catalyst, an electrolyte, and a solvent to prepare a suspension.
(Ii) the suspension prepared in step (i), the steps of preparing the catalyst ink by adding an inorganic salt to generate a metal ion in the suspension,
(Iii) A method for manufacturing a fuel cell catalyst layer, which comprises a step of preparing a fuel cell catalyst layer from the catalyst ink prepared in the steps (ii).

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