JP2000299119A - Manufacture of catalyst layer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To directly form a uniform catalyst layer n an electrolyte film to permit high output by forming the catalyst layer containing a catalyst and an electrolyte, on one surface or both surfaces of the electrolyte film containing alcohol with a specific number of carbon or less. SOLUTION: An alcohol treatment for dipping an electrolyte film in alcohols to include alcohols is applied. The alcohols are to have the carbon number of four or less. The electrolyte film 1 subjected to the alcohol treatment is disposed on a plate 2, and excess water and alcohol existing between the plate 2 and the electrolyte film 1 subjected to a alcohol treatment are squeezed out using a squeegee blade or the like to bring the electrolyte film 1 subjected to alcohol treatment, into close contact with the plate 2. A frame-like sheet 3 with an opening is disposed at the electrolyte film 1 subjected to alcohol treatment, and the frame-like sheet 3 is brought into close contact with the electrolyte film 1. Catalyst-dispersed material is applied to the electrolyte film 1 in the fixed state from the opening, and dried to form a catalyst layer- electrolyte joint body.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrochemical device having an electrolyte membrane, for example, a fuel cell, and more particularly to a catalyst for an electrode of a solid polymer electrolyte fuel cell and a direct methanol fuel cell.

[0002]

2. Description of the Related Art Electrochemical devices provided with an electrolyte membrane include, for example, solid polymer electrolyte fuel cells, direct methanol fuel cells, water electrolyzers, salt electrolyzers, ozone generators, oxygen separators, hydrogen separators and oxygen separators. There are sensors and so on. These electrochemical devices have a structure in which a cathode is arranged on one side of an electrolyte membrane and an anode is arranged on the other side.

As the electrolyte membrane, an ion exchange membrane having an ion exchange group such as a sulfonic acid group or a carboxylic acid group is used. For example, a perfluorosulfonic acid resin membrane, a perfluorocarboxylic acid membrane, a vinylbenzenesulfonic acid resin membrane, or the like is used. and so on. These membranes show good proton conductivity in a state containing water and function as an electrolyte.

A solid polymer electrolyte fuel cell is an electrochemical device that supplies electric power, for example, hydrogen to the anode, and oxygen, for example, to the cathode as an oxidant, and reacts electrochemically to obtain electric power. The anode and the cathode are gas diffusion electrodes, and the anode is joined to one side of the electrolyte membrane and the cathode is joined to the other side to form a gas diffusion electrode-electrolyte membrane assembly.

The gas diffusion electrode comprises a gas diffusion layer and a catalyst layer. The catalyst layers of the anode and the cathode are provided with platinum group metal particles or carbon particles carrying these particles as catalysts. For example, porous carbon paper having water repellency is used.

The gas diffusion electrode-electrolyte membrane assembly is sandwiched between a pair of gas-impermeable separators having a gas supply passage formed therein to form a unit cell as a basic unit. A plurality of such unit cells are stacked to form a solid polymer electrolyte fuel cell.

[0007] Activating the solid polymer electrolyte fuel cell, the ^{_{anode, 2H 2 → 4H + + 4e}} - At the ^{_{cathode, O 2 + 4H + + 4e}} - → 2
The electrochemical reaction of H ₂ O proceeds.

A direct methanol fuel cell is an electrochemical device that supplies electric power by supplying, for example, oxygen as an oxidizing agent to a cathode and, for example, a mixture of methanol and water as a fuel to an anode to cause an electrochemical reaction. A cathode electrode is provided on one surface of the electrolyte membrane, and an anode electrode is provided on the other surface. The cathode electrode and the anode electrode have a catalyst layer provided with, for example, platinum group metal particles, alloy particles thereof, or carbon particles carrying these particles as a catalyst.

When a direct methanol fuel cell is operated, CH ₃ OH + H ₂ O → CO ₂ +6
At the H ⁺ + 6e ⁻ cathode, 3 / 2O ₂ + 6H ⁺ + 6e ⁻ → 3
The electrochemical reaction of H ₂ O proceeds.

The catalyst layer in which the electrochemical reaction proceeds is made from a paste or slurry catalyst dispersion containing at least an electrolyte solution and a catalyst. For example, USP
No. 5211984 proposes a method in which a catalyst layer is formed on a release paper from a catalyst dispersion, and then the catalyst layer is transferred to an electrolyte membrane by heating and pressing.

Japanese Patent Publication No. 2-7398 proposes a method in which a sheet-like catalyst layer is formed from a catalyst dispersion and is heated and pressed integrally with an electrolyte membrane. In addition, a method in which a catalyst dispersion is applied to an electron conductive substrate to form a catalyst layer, and then heated and pressed integrally with the electrolyte membrane, or
Various methods have been proposed for forming a catalyst layer by applying a catalyst dispersion to an electrolyte membrane.

Other than the above, for example, Japanese Patent Publication No. 59-4207
No. 8 and Japanese Patent Publication No. 2-43830 propose a method of performing electroless plating of a platinum group metal on the surface of an electrolyte membrane.

[0013]

As described above, in the case of a method for manufacturing a catalyst layer-electrolyte assembly in which a catalyst layer is prepared in advance and then integrated with an electrolyte membrane by transfer or heat pressure welding, the electrolyte membrane and the electrolyte membrane are combined. It is often difficult to produce a good joined body with the catalyst layer.

One of the causes is that the electrolyte membrane changes its size depending on the water content. When joining the catalyst layer to the electrolyte membrane in a dry state, it is necessary to include water after joining. However, when water is included in the electrolyte membrane in a dry state, its size increases by 10 to 20%. As a result, the catalyst layer of the formed catalyst layer-electrolyte assembly is peeled, dropped, and cracked, and the uniformity is reduced. On the other hand, when the catalyst layer is bonded to the electrolyte membrane containing water, the electrolyte membrane is deformed due to a sudden change in the water content and the temperature of the electrolyte membrane during heating and pressing, and the catalyst layer and the electrolyte membrane are deformed. Uniformity decreases.

Further, these production methods include at least a step of forming a catalyst layer, a step of bonding with an electrolyte membrane, and a multi-step step, and various measures are required to avoid the above-mentioned reduction in uniformity. The manufacturing process becomes complicated.

As a method of bonding the catalyst layer to the electrolyte membrane as described above, there is a method of directly applying the catalyst dispersion to the electrolyte membrane. When the catalyst dispersion is directly applied to the electrolyte membrane in a dry state, water and alcohols contained in the catalyst dispersion are absorbed by the electrolyte membrane and the dimensions thereof are significantly changed. For this reason, it is difficult to form a uniform catalyst layer on the electrolyte membrane. On the other hand, when the catalyst dispersion is directly applied to the electrolyte membrane containing water, the influence on the dimensional change of the electrolyte membrane due to the absorption of water or alcohol contained in the above-described catalyst dispersion is relatively small, Nevertheless, countermeasures are required to form a uniform catalyst layer. Further, since the affinity between the electrolyte membrane and the catalyst dispersion is poor, the catalyst dispersion cannot be uniformly applied depending on the application method, and it is difficult to form a uniform catalyst layer.

An object of the present invention is to solve the above-mentioned problems, and an object of the present invention is to provide a simple method for producing a catalyst layer-electrolyte assembly in which a uniform catalyst layer is directly formed on an electrolyte membrane. The present invention provides a high-performance electrochemical device using the catalyst layer-electrolyte assembly having the uniform catalyst layer, and particularly provides a high-output solid polymer electrolyte fuel cell and a direct methanol fuel cell. Is what you do.

[0018]

In a simple method for producing a catalyst layer, in which a catalyst mixture containing at least a solution of a catalyst and an electrolyte is directly applied to the electrolyte membrane, the electrolyte membrane is impregnated with an alcohol by impregnating the electrolyte membrane with an alcohol. The affinity with the dispersion can be improved, and the dimensional change of the electrolyte membrane due to the change in the water content of the electrolyte membrane can be suppressed. Further, by fixing the electrolyte membrane to a flat plate and covering it with a frame-shaped sheet, it is possible to suppress a dimensional change due to a change in the water content of the electrolyte membrane, and to uniformly apply the catalyst dispersion, thereby enabling Catalyst layer with uniform catalyst layer
A method for manufacturing an electrolyte conjugate is provided.

According to a first aspect of the present invention, there is provided a method for producing a catalyst layer-electrolyte assembly, wherein a catalyst layer containing a catalyst and an electrolyte is formed on one or both sides of an electrolyte membrane containing an alcohol having 4 or less carbon atoms. It is.

According to a second aspect of the present invention, there is provided a frame-like sheet having an electrolyte membrane impregnated with an alcohol having 4 or less carbon atoms, then arranging the electrolyte membrane on a flat plate, and then having an opening on the upper surface of the electrolyte membrane. And then applying a catalyst dispersion containing a catalyst and an electrolyte to the electrolyte membrane from the opening of the frame-shaped sheet, thereby producing a catalyst layer-electrolyte assembly.

The third invention is a method for manufacturing a catalyst layer-electrolyte assembly, wherein the thickness of the catalyst layer is controlled by the thickness of the frame-shaped sheet having the opening.

According to a fourth aspect of the present invention, there is provided an electrochemical device including the catalyst layer-electrolyte assembly manufactured by the above-described manufacturing method.

A fifth invention is characterized in that the electrochemical device is a solid polymer electrolyte fuel cell or a direct methanol fuel cell.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION A catalyst layer-electrolyte assembly according to the present invention is a method for preparing a catalyst dispersion containing at least a catalyst and an electrolyte solution to prepare an electrolyte membrane containing water, alcohols or a mixture thereof. It is formed by directly applying the catalyst dispersion to the catalyst. Further, an electrolyte membrane containing water, alcohols or a mixture thereof is arranged on a flat plate, and a frame-shaped sheet having an opening on the upper surface thereof is further arranged, and the catalyst dispersion is directly applied from the opening. It is formed by this.

As the catalyst, particles of a platinum group metal or an alloy thereof or carbon carrying them can be used.

As the electrolyte solution, for example, a solution prepared by dissolving a perfluorosulfonic acid resin, a perfluorocarboxylic acid resin, or a vinylbenzenesulfonic acid resin in a mixed solvent of water and an alcohol can be used. As a solution of the fluorosulfonic acid resin, a 5 wt% solution of Nafion can be used.

The solvent of the electrolyte solution is an alcohol having 4 or less carbon atoms, such as methanol, ethanol,
-Propanol, 2-propanol, 1-butanol, 2-butanol, a mixture thereof, or a mixture thereof with water can be used.

The catalyst dispersion contains at least a solution of a catalyst and an electrolyte, and at least a solution of the catalyst and the electrolyte is dispersed in a dispersion medium. The dispersion medium is an alcohol having 4 or less carbon atoms, such as methanol, ethanol,
-Propanol, 2-propanol, 1-butanol, 2-butanol, a mixture thereof, or a mixture thereof with water can be used. At least a solution of a catalyst and an electrolyte is added to the dispersion medium and stirred, and the viscosity of the dispersion medium is adjusted by returning the amount of the dispersion medium to prepare a slurry or paste catalyst dispersion.

As the electrolyte membrane, an ion exchange membrane having an ion exchange group such as a sulfonic acid group or a carboxylic acid group is used.
For example, there are a perfluorosulfonic acid resin film, a perfluorocarboxylic acid film, and a vinylbenzenesulfonic acid resin film.
These ion exchange membranes exhibit proton conductivity in a state containing water and function as an electrolyte membrane.

A catalyst dispersion is directly applied to these electrolyte membranes to form a catalyst layer-electrolyte assembly. At this time, after the electrolyte membrane is washed and protonated, the catalyst dispersion is applied by incorporating water and alcohols. For example, a commercially available electrolyte membrane is washed several times with purified water, boiled with an aqueous hydrogen peroxide solution to perform a degreasing treatment, and further washed several times with purified water. Next, after boiling with an acidic aqueous solution such as dilute sulfuric acid to replace the counter ion of the electrolyte membrane with a proton type, the electrolyte membrane is washed several times with purified water and subjected to a protonation treatment.

Further, the electrolyte membrane is immersed in alcohols and subjected to alcohol treatment for containing alcohols. The alcohols are alcohols having 4 or less carbon atoms,
For example, methanol, ethanol, 1-propanol,
2-propanol, 1-butanol, 2-butanol and the like can be used. The alcohol treatment may be performed by, for example, spraying alcohols on the electrolyte membrane in addition to immersion. In short, alcohol may be contained in the electrolyte membrane.

By including alcohols in the electrolyte membrane, the affinity for the catalyst dispersion containing alcohols is improved, and the shape change of the electrolyte membrane due to absorption of water or alcohols from the catalyst dispersion is suppressed. be able to. Note that an electrolyte membrane that has been subjected to only alcohol treatment without performing degreasing treatment or protonation treatment can also be used.

An electrolyte membrane subjected to alcohol treatment is arranged on a flat plate, preferably adhered to each other, and a frame-shaped sheet having an opening is further arranged so as to cover the electrolyte membrane.
Preferably, they are brought into close contact, and the catalyst dispersion is applied from the opening.

FIGS. 1, 2 and 3 show an example of this state. FIG. 3 shows components necessary for the method for applying a catalyst dispersion of the present invention. In FIG. 3, 1 is an electrolyte membrane subjected to alcohol treatment, 2 is a flat plate, 3 is a frame-shaped sheet having an opening, 4 is an opening of the frame-shaped sheet 3 having an opening, and 5 is an opening. Framed sheet 3 having
Shows the frame part. Each size increases in the order of the opening 4, the electrolyte membrane 1 subjected to alcohol treatment, the frame-shaped sheet 3 having the opening, and the flat plate 2.

FIG. 1 is a diagram showing a state in which an electrolyte membrane 1, a flat plate 2, and a frame-shaped sheet 3 having openings are disposed from the upper side when alcohol treatment is performed. The alcohol-treated electrolyte membrane 1 is arranged so as not to protrude from the flat plate 2 and at least a part of any side of the frame portion 5 overlaps the alcohol-treated electrolyte membrane 1.

FIG. 2 is a cross-sectional view showing a state in which an electrolyte membrane 1, a flat plate 2, and a frame-shaped sheet 3 having an opening are disposed after alcohol treatment. Electrolyte-treated electrolyte membrane 1 and flat plate 2, alcohol-treated electrolyte membrane 1
And the frame 5, and the flat plate 2 and the frame 5 are in close contact with each other.

The flat plate 1 has only to be larger than the electrolyte membrane subjected to the alcohol treatment and has a smoothness such that the electrolyte membrane containing water and alcohol adheres to each other. For example, any material such as glass, metal or plastic can be used. But it doesn't matter.

The shape of the opening 4 may be any shape such as a polygon such as a square or a rectangle, a circle, an ellipse, or the like, and is selected according to the required shape and size of the catalyst layer. It is preferable that the size of the outer peripheral portion of the frame portion is larger than the electrolyte membrane subjected to the alcohol treatment, and that the electrolyte membrane subjected to the alcohol treatment located outside the opening is covered with the frame portion 5. desirable.

The frame-shaped sheet 3 having the openings can be made of a material that hardly permeates water or alcohol and does not cause dimensional changes such as swelling by absorbing them. For example, polymers such as polyethylene, polyvinyl chloride and polytetrafluoroethylene, or metals such as aluminum foil and copper foil can be used.

Next, an example of a method for forming a state in which the electrolyte membrane 1, the flat plate 2, and the frame portion 5 which have been subjected to the above-described alcohol treatment are in close contact with each other will be described. The alcohol-treated electrolyte membrane was arranged on a flat plate, and excess water or alcohol existing between the flat plate and the alcohol-treated electrolyte membrane was handled using, for example, a squeegee blade, and the alcohol treatment was performed. The electrolyte membrane can be adhered to the flat plate.
In addition to a squeegee blade, it is also possible to use a roller or the like. In short, it is sufficient to remove the excess water or alcohol and bring the electrolyte membrane subjected to alcohol treatment into close contact with the flat plate.

Next, a frame-shaped sheet having an opening is disposed on the alcohol-treated electrolyte membrane, and excess water existing between the frame-shaped sheet and the electrolyte membrane is removed using, for example, a squeegee blade. Alcohol is taken out and the frame sheet is brought into close contact with the electrolyte membrane. In this way,
The electrolyte membrane treated with ethanol as shown in FIGS. 1 and 2 is arranged on a flat surface on one side and covered with a frame-shaped sheet having an opening on the other side to form a fixed electrolyte membrane.

Next, a catalyst dispersion is applied to the fixed electrolyte membrane from the opening and dried to form a catalyst layer-electrolyte assembly. In the application method, for example, the paste-like catalyst dispersion can be uniformly applied to the electrolyte membrane located at the opening by sweeping the squeegee blade.

One example of the application of the catalyst dispersion is shown in FIGS. FIG. 4 is a schematic diagram showing a state in which the catalyst dispersion is disposed in the method for applying a catalyst dispersion of the present invention.
In the electrolyte membrane 1 subjected to alcohol treatment, which is fixed by being sandwiched between the flat plate 2 and the frame-shaped sheet 3 having an opening, an appropriate amount of the catalyst dispersion 6 is disposed in the frame 5.

FIG. 5 is a schematic view showing a state in which the catalyst dispersion is stretched by a squeegee blade in the method of applying the catalyst dispersion of the present invention. Reference numeral 7 denotes a squeegee blade, 8 denotes a coated catalyst dispersion, and 9 denotes a direction in which the squeegee blade is swept. The catalyst dispersion 6 is applied to the alcohol-treated electrolyte membrane 1 located at the opening 4 according to the thickness of the frame-shaped sheet 3 having the opening.

FIG. 6 is a schematic diagram showing a state where the catalyst dispersion is applied by sweeping with a squeegee blade in the method of applying the catalyst dispersion of the present invention. After applying the catalyst dispersion,
Dry at room temperature. Then, the applied catalyst dispersion is fixed to the electrolyte membrane, and this portion becomes a catalyst layer. During this drying process, the electrolyte membrane does not directly contact the outside air,
The dimensional change of the electrolyte membrane due to drying can be minimized.

After drying, a frame-shaped sheet 3 having an opening
Is removed, a catalyst layer-electrolyte assembly having the catalyst layer 10 formed on the surface of the electrolyte membrane 1 is obtained. This catalyst layer 10
Is uniform without being affected by peeling, falling off, or formation of cracks due to dimensional change of the electrolyte membrane.

In addition to the squeegee blade, a rod-shaped or plate-shaped metal, plastic, or glass material can be used for coating the catalyst dispersion. I just want to be able.

At this time, by adjusting the thickness of the frame-shaped sheet having openings, and adjusting the amount of the solvent of the catalyst dispersion, a catalyst layer having an arbitrary thickness can be formed.
Typically 3 to 50 μm, preferably 5 to 15 μm
Can be formed.

Alternatively, in addition to the method of spreading and applying the catalyst dispersion, it is also possible to apply the catalyst dispersion by, for example, a spray coating or screen coating method.

The applied catalyst dispersion is left to dry at room temperature for several minutes. However, since the electrolyte membrane is adhered to a flat plate and covered with a frame-shaped sheet, it does not dry excessively. No dimensional change in the surface direction of the electrolyte membrane is observed.

After the applied catalyst dispersion was dried to form a catalyst layer, the frame-shaped sheet was removed and the catalyst layer was removed from the flat plate.
Take the electrolyte conjugate and store it immersed in purified water. Even when immersed in purified water, there is no dimensional change of the electrolyte membrane such that the formed catalyst layer falls off or cracks occur. The electrolyte membrane on which the catalyst layer is formed contains alcohol, but the alcohol contained is removed from the electrolyte membrane by immersion in purified water.

[0052]

[Example 1] An example of a method for manufacturing a solid polymer electrolyte fuel cell using the catalyst layer of the present invention will be specifically described.

First, a catalyst dispersion comprising a solution of a catalyst and an electrolyte was prepared. The catalyst used was a carbon powder carrying 30 wt% of platinum, and the electrolyte solution used was a commercially available 5 wt% Nafion solution. 1.5 g of the catalyst was added to 13 ml of a 5 wt% Nafion solution and stirred for 30 minutes to disperse the catalyst, and then heated to 60 ° C. with stirring, so that the weight of the solid content of Nafion was 15 wt% with respect to the dispersion medium. And concentrated to. This was designated as catalyst dispersion A.

Next, the electrolyte membrane was washed, protonated, and immersed in alcohol. As the electrolyte membrane, a commercially available Nafion 115 membrane was used. After washing the Nafion 115 membrane three times with purified water, 3 g
Boiling for 1 hour in water, washed several times with purified water, and further treated with 0.5 M sulfuric acid for protonation.
The mixture was boiled for an hour, washed several times with purified water, and stored in purified water. Subsequently, the Nafion 115 membrane was immersed in ethanol for 10 minutes as a process for including ethanol in the electrolyte membrane.

Next, 52.5 μm thick tetrafluoroethylene-hexafluoropropylene copolymer sheet was added
A frame-shaped sheet having an opening of cm × 5 cm was prepared. The Nafion 115 film subjected to the protonation treatment and the alcohol treatment is placed on a glass plate, and a frame-shaped sheet having an opening is placed. Then, using a squeegee blade, the Nafion 115 film is placed between the glass plate and the Nafion 115 film. Excess water and ethanol between the sheet and the frame-like sheet were taken, and the Nafion 115 film was brought into close contact with the glass plate, and the frame-like sheet was brought into close contact with the Nafion 115 film. At this time, excess water and ethanol on the surface of the Nafion 115 film located at the opening of the frame-shaped sheet were also removed.

The catalyst dispersion A was applied to the Nafion 115 film located at the opening. An appropriate amount of the catalyst dispersion A was taken in the frame near the opening, and was applied to the Nafion 115 film located in the opening by sweeping with a squeegee blade. afterwards,
The catalyst dispersion A was dried by leaving it at room temperature to dry Nafion 11
A catalyst layer having a thickness of about 8 μm was formed on the five membranes and stored in purified water.

Nafion 115 having a catalyst layer formed on one side
The membrane is taken out of the purified water, installed so that the surface on which the catalyst layer is formed faces the glass plate, and is present between the glass plate and the Nafion 115 film having the catalyst layer formed on one surface using a squeegee blade. The water was taken and they were brought into close contact.

Next, after spraying ethanol on the other surface of the Nafion 115 film, a frame-shaped sheet having an opening similar to that described above is arranged, and a catalyst layer is formed on one surface using a squeegee blade. Handle the ethanol present between the Nafion 115 membrane and the framed sheet,
They adhered. At this time, excess alcohol on the surface of the Nafion 115 film located at the opening of the frame-shaped sheet was also removed. The catalyst layer formed on one side and the opening of the frame-shaped sheet disposed on the other side were arranged so as to overlap with each other via a membrane.

Next, an appropriate amount of the catalyst dispersion A was taken in the frame near the opening in the same manner as described above, and the squeegee blade was swept to apply the catalyst dispersion A to the Nafion 115 film in the opening.
Thereafter, the catalyst dispersion A was dried at room temperature to prepare a catalyst layer-electrolyte assembly having a catalyst layer having a thickness of about 8 μm also formed on the other surface of the Nafion 115 membrane, and stored in purified water.

Each of the catalyst layers formed on the above-mentioned Nafion 115 film has a thickness of 0.2 mm and a size of 5 cm × 5c.
120 kg / c of carbon paper having water repellency of
The electrode-electrolyte membrane assembly was produced by bonding by heating and pressing for 5 minutes at 130 ° C. for 5 minutes. This is the electrode
An electrolyte membrane assembly A was obtained.

The polymer electrolyte fuel cell A was constituted by sandwiching the electrode-electrolyte membrane assembly A between a pair of metal separators having gas channels formed therein.

Comparative Example For comparison, a solid polymer electrolyte fuel cell was manufactured using a catalyst layer by a conventional transfer method. First, the catalyst dispersion A prepared in Example 1 was applied to an aluminum foil by screen printing using 300 mesh, and then dried to form a catalyst layer having a thickness of about 8 μm.
It was cut into a size of 5 cm.

Next, cleaning and cleaning were performed in the same manner as in Example 1.
On both sides of the tonified Nafion 115 membrane,
The catalyst layer formed on the aluminum foil was installed, and 120 kg /
cm ^Two90 ° C, 90 seconds for heating and pressure contact to nap the catalyst layer
To a catalyst layer-electrolyte assembly
Was. At this time, the catalyst layer formed into a thin aluminum layer is Nafion 1
15 catalyst on one side facing the membrane and through the membrane
The layers were arranged such that the positions of the layers and the catalyst layer on the other side coincided with each other.

As in the first embodiment, the above-mentioned Nafion 11
Each of the catalyst layers formed in the five films has a thickness of 0.2 mm,
A 5 cm × 5 cm water-repellent carbon paper was heated and pressed at 120 kg / cm ² at 130 ° C. for 5 minutes to form an electrode-electrolyte membrane assembly. This was designated as electrode-electrolyte membrane assembly B.

The polymer electrolyte fuel cell B was constituted by sandwiching the electrode-electrolyte membrane assembly B between a pair of metal separators having gas channels formed therein.

The current-voltage characteristics of the solid polymer electrolyte fuel cell A manufactured in Example 1 and the solid polymer electrolyte fuel cell B manufactured in Comparative Example were measured. These solid polymer electrolyte fuel cells were operated under the same conditions. That is, pure hydrogen was used as the fuel gas, and the fuel gas was humidified by a bubbler humidifier set at 60 ° C., and then supplied to the battery at a flow rate at which the utilization factor became 70%. Using pure oxygen as the oxidizing gas, 60
After humidification with a bubbler humidifier set to ° C., the battery was supplied to the battery at a flow rate at which the utilization factor became 50%. The reaction gases were each supplied at atmospheric pressure. Coolant at 65 ° C. was circulated through the battery to keep the battery temperature constant.

FIG. 7 shows the current-voltage characteristics of the solid polymer electrolyte fuel cell A manufactured in Example 1 and the solid polymer electrolyte fuel cell B manufactured in the comparative example. As is clear from FIG. 7, the catalyst layer formed by the method of directly applying the catalyst dispersion to the electrolyte membrane (the Nafion 115 membrane in the example) has a small decrease in the battery voltage at a high current density and has excellent characteristics. Indicated. It has been shown that the catalyst layer of the present invention is effective in increasing the output of a solid polymer electrolyte fuel cell in addition to the simple manufacturing method.

Example 2 An example of a method for manufacturing a direct methanol fuel cell using the catalyst layer-electrolyte assembly of the present invention will be specifically described.

In the same manner as in Example 1, a catalyst dispersion comprising a solution of a catalyst and an electrolyte was prepared. The catalyst is platinum 20w
Using a carbon powder carrying 20% by weight of t% and ruthenium, a commercially available 5% by weight Nafion solution was used as the electrolyte solution. After adding 1.5 g of the catalyst to 11.2 ml of a 5 wt% Nafion solution and stirring for 30 minutes to disperse the catalyst, the mixture was heated to 60 ° C. with stirring, and the weight of the solid content of Nafion with respect to the dispersion medium was reduced. It was concentrated to 15 wt%. This was designated as catalyst dispersion C.

In the same manner as in Example 1, a Nafion 115 membrane subjected to washing, protonation, and ethanol treatment was arranged in a glass plate shape, and a frame-shaped sheet having an opening was arranged. Then, using a squeegee blade, Excess water and ethanol were handled, and the Nafion 115 film, the glass plate, and the frame-shaped sheet were brought into close contact with each other. This frame-shaped sheet was 12.5 μm in the same manner as used in Example 1.
m having a 5 cm × 5 cm opening in a tetrafluoroethylene-hexafluoropropylene copolymer sheet was used. At this time, excess water and ethanol on the surface of the Nafion 115 film located at the opening of the frame-shaped sheet were also removed.

In the same manner as in Example 1, Nafion 11
Catalyst dispersion C was applied to five films to form a catalyst layer. That is, an appropriate amount of the catalyst dispersion C was taken in a frame portion near the opening, and was applied to the Nafion 115 film in the opening by sweeping with a squeegee blade. Thereafter, the catalyst dispersion C was dried at room temperature to form a catalyst layer having a thickness of about 8 μm on a Nafion 115 membrane, and stored in purified water. Next, the Nafion 115 film having the catalyst layer formed on one side is taken out of the purified water, and placed so that the surface on which the catalyst layer is formed faces the glass plate, and the catalyst layer is formed on one side using a squeegee blade. The water present between the Nafion 115 film and the glass plate was removed and brought into close contact.

Next, after spraying ethanol on the other surface of the Nafion 115 film, a frame-like sheet having the same opening as that described above was arranged, and a catalyst layer was formed on one surface using a squeegee blade. Ethanol existing between the Nafion 115 film and the frame-shaped sheet was handled and brought into close contact. At this time, excess ethanol on the surface of the Nafion 115 film located at the opening of the frame-shaped sheet was also removed. The catalyst layer formed on one side and the opening of the frame-shaped sheet disposed on the other side were arranged so as to overlap with each other via a membrane.

Next, in the same manner as described above, an appropriate amount of the catalyst dispersion A was taken in the frame near the opening, and the squeegee blade was swept to apply it to the Nafion 115 film in the opening.
After that, the catalyst dispersion A was dried at room temperature to form a catalyst layer having a thickness of about 8 μm on the other surface of the Nafion 115 membrane, and a catalyst layer-electrolyte assembly was prepared and stored in purified water. .

The catalyst layer composed of the catalyst dispersion C formed on one surface of the above-mentioned Nafion 115 membrane was added with a thickness of 0.2 m.
m, a carbon paper having a size of 5 cm × 5 cm, and a water-repellent carbon paper in a catalyst layer made of the catalyst dispersion A formed on the other surface were applied at 120 kg / cm 2, 130
Each was joined by heating and pressure welding at a temperature of 5 ° C. for 5 minutes to produce an electrode-electrolyte membrane assembly. This is the electrode
An electrolyte membrane assembly C was obtained.

[0075] The electrode-electrolyte membrane assembly C was sandwiched between a pair of metal separators in which gas channels were processed, to directly construct a methanol fuel cell C. The fuel layer (anode) of the direct methanol fuel cell C has a catalyst layer made of a catalyst dispersion C containing a carbon catalyst supporting platinum and ruthenium, and the air electrode (cathode) has a carbon catalyst supporting platinum. Each of the catalyst layers produced from the catalyst dispersion A containing

This direct methanol fuel cell was operated under the following conditions, and the current-voltage characteristics were measured. Oxygen pressurized to 3 atm was supplied to the cathode, and 1 M methanol / water pressurized to 2 atm was supplied to the anode. 1 for battery
A 10 ° C. coolant was circulated to keep the cell temperature constant.

FIG. 8 shows the current-voltage characteristics of the direct methanol fuel cell C manufactured in Example 2. It was confirmed that the method for producing a catalyst layer of the present invention is also effective for a direct methanol fuel cell.

[0078]

The present invention provides a method for producing a catalyst layer-electrolyte assembly in which a uniform catalyst layer is formed on an electrolyte membrane, and the catalyst layer of the catalyst layer-electrolyte assembly produced by the production method of the present invention comprises: An electrochemical device using a catalyst layer-electrolyte assembly having a uniform catalyst layer without being affected by peeling, falling off or cracking caused by a dimensional change of the electrolyte membrane,
In particular, the solid polymer electrolyte fuel cell and the direct methanol fuel cell can have high output.

[Brief description of the drawings]

FIG. 1 is a diagram showing a state in which an electrolyte membrane, a flat plate, and a frame-shaped sheet having an opening are disposed after alcohol treatment, as viewed from above.

FIG. 2 is a diagram showing a state in which an electrolyte membrane 1, a flat plate 2, and a frame-shaped sheet 3 having openings are arranged in an alcohol treatment, as viewed from a cross-sectional direction.

FIG. 3 shows components necessary for the method for applying a catalyst dispersion of the present invention.

FIG. 4 is a schematic diagram showing a state in which the catalyst dispersion is arranged in the method for applying the catalyst dispersion of the present invention.

FIG. 5 is a schematic view showing a state in which the catalyst dispersion is stretched by a squeegee blade in the method for applying the catalyst dispersion of the present invention.

FIG. 6 is a schematic view showing a state where the catalyst dispersion is applied by sweeping with a squeegee blade in the method for applying the catalyst dispersion of the present invention.

FIG. 7 shows a solid polymer electrolyte fuel cell A constructed using an electrode-electrolyte membrane assembly provided with a catalyst layer of the present invention and an electrode-electrolyte membrane assembly provided with a catalyst layer produced by a conventional method. FIG. 4 is a diagram showing current-voltage characteristics of a solid polymer electrolyte fuel cell B configured as described above.

FIG. 8 is a view showing current-voltage characteristics of a direct methanol fuel cell C constituted by using an electrode-electrolyte membrane assembly provided with a catalyst layer of the present invention.

[Brief description of reference numerals]

 Reference Signs List 1 electrolyte membrane subjected to alcohol treatment 2 flat plate 3 frame-shaped sheet having opening 4 opening of frame-shaped sheet 3 having opening 5 frame of frame-shaped sheet 3 having opening 6 catalyst dispersion 7 squeegee blade 8 Applied catalyst dispersion 9 sweep direction of squeegee blade 10 catalyst layer

Claims (5)

[Claims] 1. An electrolyte membrane impregnated with an alcohol having 4 or less carbon atoms, and then, on one or both sides of the electrolyte membrane,
A method for producing a catalyst layer-electrolyte assembly, comprising forming a catalyst layer containing a catalyst and an electrolyte. 2. An electrolyte membrane is impregnated with an alcohol having 4 or less carbon atoms, and then the electrolyte membrane is arranged on a flat plate.
2. A frame-shaped sheet having an opening on the upper surface of the electrolyte membrane, and a catalyst dispersion containing a catalyst and an electrolyte is applied to the electrolyte membrane from the opening of the frame-shaped sheet. The method for producing a catalyst layer-electrolyte assembly according to the above. 3. The method for producing a catalyst layer-electrolyte assembly according to claim 2, wherein the thickness of the catalyst layer is controlled by the thickness of the frame-shaped sheet having openings. 4. An electrochemical device comprising a catalyst layer-electrolyte assembly produced by the production method according to claim 1. Description: 5. The electrochemical device according to claim 4, wherein the electrochemical device is a solid polymer electrolyte fuel cell or a direct methanol fuel cell.