JP2006309953A - Electrode, battery and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrode having a good dispersion state of catalyst carrying carbon powder and hydrogen ion conductive polymers, and excellent hydrogen ion conductivity, and also to provide a battery and its manufacturing method. <P>SOLUTION: The manufacturing method contains processes of: preparing catalyst ink by dissolving at least catalyst carrying carbon, a hydrogen ion conductive polymer electrolyte, and a polymer dispersant in a solvent; dispersing the catalyst ink; and laminating dispersed catalyst ink on a substrate, and the dispersed catalyst ink is manufactured by using a pressure nozzle type emulsifier. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

The present invention relates to a polymer electrolyte fuel cell electrode and a polymer electrolyte fuel cell.

A fuel cell using hydrogen and oxygen is attracting attention as a power generation system that has almost no adverse environmental impact because its reaction product is essentially only water.
In recent years, a polymer electrolyte fuel cell using an ion exchange membrane having hydrogen ion conductivity as an electrolyte among fuel cells has a low operating temperature, a high output density, and can be easily downsized. It is expected to be used for in-vehicle power supplies.

The polymer electrolyte fuel cell is characterized by a low operating temperature (50 to 120 ° C.) as described above. However, it is difficult for the exhaust heat to be effectively used for auxiliary power.
In order to supplement this, the polymer electrolyte fuel cell is required to have a performance capable of obtaining a high power generation efficiency and a high output density under an operating condition with a high utilization rate of hydrogen and oxygen.

A polymer electrolyte fuel cell is generally formed by laminating a large number of single cells.
A single cell has a structure in which a membrane / electrode assembly joined by sandwiching a solid polymer membrane between two electrodes (anode electrode and cathode electrode) is sandwiched by a separator having a gas flow path of fuel gas or oxidant gas. ing.

The gas diffusion layer and catalyst layer constituting the electrode of the fuel cell will be described.
The gas diffusion layer mainly has the following three functions.
The first is the function of diffusing the reaction gas for uniformly supplying the reaction gas to the catalyst in the catalyst layer from the gas flow path on the separator surface in contact with the gas diffusion layer.
The second function is to quickly discharge water produced by the reaction in the catalyst layer to the gas flow path.
The third is a function of conducting electrons necessary for the reaction or generated electrons.
That is, the gas diffusion layer is required to have excellent reaction gas permeability, water vapor permeability, and electronic conductivity.

As a conventional general technique, a porous substrate such as carbon paper and carbon cloth is used for the gas diffusion layer in order to ensure good gas permeability.
In order to ensure good water vapor permeability, a water repellent polymer typified by a fluororesin is dispersed in the gas diffusion layer.
Furthermore, in order to ensure good electron conductivity, a gas diffusion layer is made of an electron conductive material such as carbon fiber, metal fiber, and carbon powder.

Next, the catalyst layer mainly has the following four functions.
The first is a function of supplying a reaction gas such as fuel gas or oxidant gas supplied from the gas diffusion layer to the reaction site of the catalyst layer.
The second function is to quickly transfer hydrogen ions necessary for the reaction on the catalyst or generated hydrogen ions to the electrolyte membrane.
The third is a function of conducting electrons necessary for the reaction or generated electrons.
The fourth function is to promote the electrode reaction.
That is, the catalyst layer needs to have excellent reaction gas permeability, hydrogen ion conductivity, electron conductivity, catalyst performance, and a wide reaction area.

As a conventional general technique, in order to ensure good gas permeability, the catalyst layer is made porous by using carbon powder or a pore-forming material constituting a porous chain aggregate in the catalyst layer. It is done to structure.
In order to ensure good hydrogen ion conductivity, a polymer electrolyte is dispersed in the vicinity of the catalyst in the catalyst layer to form a hydrogen ion conduction network.
In order to ensure good electron conductivity, a catalyst carrier is made of an electron conductive material such as carbon powder or carbon fiber.
Furthermore, in order to ensure good catalyst performance, a highly reactive metal catalyst represented by platinum is supported on carbon powder as very fine particles with a particle size of several nanometers, and is highly dispersed in the catalyst layer. Has been done.

However, it is very difficult to form a good hydrogen ion conduction network by dispersing the hydrogen ion conductive polymer electrolyte in the vicinity of the catalyst in the catalyst layer.
In general, when the specific surface area of carbon powder used in the catalyst layer is several 10 to several 1500 m ² / g, primary particles of several 10 nm are combined to form a chain aggregate.
The catalyst is supported in pores of several nm to several hundred nm formed inside the chain aggregate.
Therefore, it is difficult to uniformly disperse a hydrogen ion conductive polymer electrolyte having a particle size of several hundred nm in the vicinity of the catalyst.
For this reason, it is difficult to ensure a sufficient effective reaction area of the catalyst.

In addition, it is difficult to form a hydrogen ion conduction network by bonding hydrogen ion conductive polymer electrolytes, and there is a problem that sufficient hydrogen ion conductivity cannot be ensured.

Since the carbon powder used for the catalyst layer forms a chain aggregate, the catalyst powder prepared by mixing the catalyst-supporting carbon, the hydrogen ion conductive polymer electrolyte, and the solvent has a very high carbon powder. Easy to aggregate.
Therefore, in a normal stirring or dispersion method using a stirrer or an ultrasonic bath, the particles in the catalyst ink exhibit a particle size distribution having a median diameter of several tens of μm.
Therefore, when a catalyst ink is applied to an electrolyte membrane, a gas diffusion layer, or a base sheet, an agglomerated layer of powder having a particle size of several tens of μm is formed as a catalyst layer, and the catalyst is a dense and smooth catalyst thinner than several tens of μm. It was difficult to obtain a layer.

In the gas diffusion layer, various surfactants are used in order to obtain a good dispersion state of the water repellent polymer material.
Representative examples thereof are described in JP-A-11-335886, JP-A-11-269689, JP-A-11-050290, JP-A-10-09439, and JP-A-6-116774. .
These publications disclose the use of alkylphenol octylphenol ethoxylate (trade name: Triton X-100) as a dispersant for the water-repellent polymer material.
However, the techniques disclosed in these publications are not disclosures of techniques related to the dispersion of the polymer electrolyte and the carbon powder in the catalyst layer of the present invention.

On the other hand, JP-A-8-236123, JP-A-9-180727, and JP-A-10-284086 disclose the use of a surfactant in the catalyst layer.
In these publications, a surfactant is mixed with a raw material of the catalyst layer to form a catalyst layer, and then the obtained catalyst layer is impregnated with a polymer electrolyte, or a catalyst layer that has been formed is impregnated with a surfactant. Thereafter, a method of further impregnating or coating the polymer electrolyte is disclosed.
In this case, the surfactant has a role of making it easy for the hydrogen ion conductive polymer electrolyte to penetrate into the catalyst layer.

However, in these methods, since the hydrogen ion conductive polymer electrolyte is not present in the catalyst layer when the surfactant is used, the dispersion state of both the carbon powder and the hydrogen ion conductive polymer electrolyte is changed to the interface. It cannot be controlled simultaneously by the activator.
Therefore, it is impossible to simultaneously form carbon powder in the catalyst layer and to disperse the polymer electrolyte to form a good hydrogen ion conduction network, and a dense and smooth catalyst layer cannot be obtained.

Further, for example, when a surfactant having a molecular weight of 300 to 600 disclosed in JP-A-10-284086 is added to the catalyst ink, foaming is severe during preparation of the catalyst ink, and a good catalyst ink cannot be prepared.
For this reason, a stable catalyst layer cannot be formed.

As an effective method for dispersing the catalyst ink, Japanese Patent Application Laid-Open No. 2000-164224 discloses a method using a ball mill or a homogenizer.
Japanese Patent Application Laid-Open No. 2003-77479 discloses a method using a bead mill.

However, in the case of a general fluid stirrer such as a homogenizer, there is a problem that the ink does not share and the dispersion is completely insufficient.
The effect is improved by processing the zirconia beads together in the catalyst ink, but sufficient dispersion cannot be obtained.
Further, when using a ball mill, it is basically a batch type construction method, and a process for removing the balls is further added, resulting in an increase in process cost.
Furthermore, in a dispersion method using a medium such as a ball mill or a bead mill, contamination may be mixed and the electrical characteristics of the catalyst layer may be deteriorated.

Furthermore, as a method for dispersing the catalyst ink, Japanese Patent Application Laid-Open No. 2003-68309 discloses a technique in which a pressure nozzle type emulsifier and a grinding process such as a sand mill are used in combination.

However, it is difficult to stably produce an electrode with excellent performance due to the problem of storage stability of the catalyst ink because no dispersant is used in the above method and the problem of contamination of balls used in the sand mill. It is.
JP-A-11-335886 Japanese Patent Application Laid-Open No. 11-269689 Japanese Patent Laid-Open No. 11-050290 Japanese Patent Laid-Open No. 10-092439 JP-A-6-116774 JP-A-8-236123 JP-A-9-180727, Japanese Patent Laid-Open No. 10-284086 JP 2000-164224 A JP 2003-77479 A JP 2003-68309 A

An object of the present invention is to provide an electrode having excellent hydrogen ion conductivity, a battery, and a method for producing the same, in which a catalyst-supported carbon powder and a hydrogen ion conductive polymer are well dispersed.

The invention described in claim 1 includes a step of producing a catalyst ink obtained by dissolving at least catalyst-supporting carbon, a hydrogen ion conductive polymer electrolyte, and a polymer dispersant in a solvent, and a dispersion treatment of the catalyst ink. It is a manufacturing method of an electrode characterized by having a process and the process of laminating | stacking the catalyst ink by which the dispersion process was carried out on the base-material surface.

The invention according to claim 2 is the production of the electrode according to claim 1, wherein the polymer dispersant is at least one selected from the group consisting of carboxylic acid, carboxylate and amine. Is the method.

The invention according to claim 3 is characterized in that the polymer dispersant is 0.01% by mass or more and 20% by mass or less based on the total mass of the catalyst-supporting carbon and the hydrogen ion conductive polymer electrolyte. The method for producing an electrode according to claim 2, wherein the concentration of the solid content in the catalyst ink is 1% by mass or more and 20% by mass or less.

According to a fourth aspect of the present invention, in the electrode according to any one of the first to third aspects, the catalyst ink subjected to the dispersion treatment is produced using a pressure nozzle type emulsifier. It is a manufacturing method.

The invention according to claim 5 is the method for producing an electrode according to claim 4, wherein the pressure of the pressure nozzle type emulsifier is 100 MPa or more and 1500 MPa or less.

The invention according to claim 6 is characterized in that the catalyst ink has a viscosity of 0.5 cP (poise) or more and 2000 cP (poise) or less. It is.

A seventh aspect of the present invention is the electrode manufacturing method according to any one of the first to sixth aspects, wherein the solvent has a dielectric constant of 10 or more and 82 or less.

The invention according to claim 8 is the electrode according to any one of claims 1 to 7, wherein the base material is either a gas diffusion material or a hydrogen ion conductive polymer membrane. It is a manufacturing method.

The invention according to claim 9 is that the dispersion-treated catalyst ink is applied to a transfer substrate and then transferred to the base material, or the dispersion-treated catalyst ink is transferred to the substrate. The electrode manufacturing method according to any one of claims 1 to 8, wherein the dispersion-treated catalyst ink is laminated on the surface of the base material by coating the base material. .

A tenth aspect of the present invention is an electrode manufactured by the manufacturing method according to any one of the first to ninth aspects.

The invention described in claim 11 includes a step of laminating at least the electrode according to claim 10 on the front and back surfaces of the proton conductive membrane to form an electrode / membrane assembly, and the front and back surfaces of the electrode / membrane assembly. A method of manufacturing a battery, comprising: a step of laminating a separator; a step of laminating a current collector on a surface of the separator; and a step of disposing a heater around the current collector.

The invention according to claim 12 is a battery manufactured by the manufacturing method according to claim 11.

Since the electrode and battery of the present invention have a good dispersion state of the catalyst-supporting carbon powder and the hydrogen ion conductive polymer, it is possible to have excellent hydrogen ion conductivity.
In addition, the electrode and battery manufacturing method of the present invention can reduce the cost by varying the coating amount of the catalyst ink, obtaining coating film stability, and simplifying the manufacturing process.

An example of the embodiment of the present invention will be described with reference to FIGS. 1 and 2, but the present invention is not limited to this.

First, the catalyst ink layer 2 is formed on the base material 1 (FIG. 1A).

As a material for the substrate 1, a gas diffusion material such as carbon paper or a hydrogen ion conductive polymer electrolyte can be used.

The catalyst ink layer 2 is composed of at least a catalyst-supporting carbon, a hydrogen ion conductive polymer electrolyte, a polymer dispersant, and a solvent.

As a catalyst material of the catalyst-supporting carbon, noble metals such as platinum, palladium, gold, ruthenium and iridium can be used.
The noble metal catalyst may contain two or more kinds of elements such as alloys and mixtures.

As the carbon of the catalyst-supporting carbon, artificial graphite or carbon obtained from organic compounds such as natural graphite, pitch, coke, polyacrylonitrile, and phenol resin can be used.
Carbon blacks such as oil pherbs black, channel black, lamp black, thermal black, acetylene black and ketjen black are preferred from the viewpoints of electron conductivity and specific surface area.
As the form of carbon, in addition to particulates, fibrous carbon can also be used.

As the hydrogen ion conductive polymer electrolyte, a polymer having a hydrogen ion exchange group can be used in order to improve the hydrogen ion conductivity in the catalyst layer.
As the hydrogen ion exchange group, a sulfonic acid group, a carboxylic acid group, a phosphoric acid group and the like can be used, but are not particularly limited.
Examples of such a polymer having a hydrogen ion (proton) exchange group include the above-mentioned fluorine atom-containing polymer having a proton exchange group, other polymers obtained from ethylene and styrene, copolymers and blends thereof. However, a polymer having a proton exchange group composed of a fluoroalkyl ether side chain and a fluoroalkyl main chain or a sulfonated polyarylene is preferably used, and is not particularly limited.

Examples of the polymer dispersant include the following.
Examples of the polymer dispersant composed of carboxylic acid or carboxylate include styrene-maleic anhydride copolymer, olefin-maleic anhydride copolymer, sodium polyacrylate, polyacrylamide partial hydrolyzate, acrylamide-acrylic acid A sodium copolymer, sodium alginate, etc. can be used.
As the polymer dispersant composed of amine, polyethyleneimine, polyvinylimidazoline, aminoacryl methacrylate-acrylamide copolymer, polyacrylamide, polyacrylamide Mannich modified product, chitosan and the like can be used.
Polyvinyl alcohol, a formaldehyde condensate of naphthalene sulfonate, a copolymer of polyoxyethylene ether ester, starch and the like can also be used as the polymer dispersant.

Commercially available polymer dispersants include Disperbyk 191 (produced by Big Chemie), Disparon DA-703-50 (produced by Enomoto Kasei Co., Ltd.), Politi N-100K (produced by Lion Corporation), Dimor N (produced by Kao Corporation) ) Etc. can be used.

The polymer dispersant is desirably blended in an amount of 0.01% by mass or more and 30% by mass or less with respect to the total mass of the catalyst-supported carbon and the hydrogen ion conductive polymer electrolyte. It is more preferable that the amount is not more than mass%.
When this content is less than 0.01% by mass, dispersion stability may not be obtained.
On the other hand, if the content exceeds 30% by mass, the dispersion tends to aggregate and the dispersion stability may deteriorate.

The polymer dispersant will be described with reference to “Pigment Dispersion Technology” (published by Technical Information Association).
The polymer dispersant is included in the category of surfactant in a broad sense, usually having a molecular weight of several thousand or more, consisting of a hydrophilic group and a hydrophobic group, and having both the function of the surfactant and the characteristics of the polymer. Defined as amphiphilic polymer.

A surfactant that does not correspond to a polymer dispersant has a molecular weight as small as 200 or more and less than 2000, and thus foaming easily occurs.
In addition, since the effect of its own steric hindrance is small, when a surfactant is mixed in the catalyst ink, the effect of suppressing the aggregation of the carbon powder in the catalyst ink and dispersing the polymer electrolyte is small.

On the other hand, since the molecular weight of the polymer dispersant is as large as, for example, 2000 to 200000, foaming hardly occurs.
In addition, since the effect due to its own steric hindrance is great, when a polymer dispersant is mixed in the catalyst ink, the effect of suppressing the aggregation of the carbon powder in the catalyst ink and dispersing the polymer electrolyte is great.

Moreover, since the polymer dispersant has many adsorption sites, the dispersed particles can be stabilized.
Therefore, by including the polymer dispersant in the catalyst layer, the polymer electrolyte and the carbon powder supporting the catalyst can be uniformly dispersed, and the effective reaction area of the catalyst can be sufficiently ensured.

As described above, since the dispersed particles of the carbon powder supporting the polymer electrolyte and the catalyst are stably present, the stability of the catalyst ink containing them is increased.
For this reason, in the manufacturing process such as application and printing of the catalyst ink, clogging of the catalyst ink in a pipe or a pump or a change in the concentration of the catalyst ink during storage can be suppressed.
Furthermore, variations in coating amount during coating and poor coating are reduced, and adhesion to the polymer electrolyte membrane and the gas diffusion layer is improved.

As the solvent, alcohol and water can be used.
In particular, the mixed solution is preferable.
The type of alcohol is preferably a compound having 1 to 6 carbon atoms.
Furthermore, among these compounds, compounds having a boiling point of 40 to 160 ° C are preferable, and compounds having a boiling point of 60 to 120 ° C are more preferable.
Specific examples of preferable solvents satisfying the above conditions include alcohols such as methanol, ethanol, n-propanol, 2-propanol, 1-butanol, and 2-butanol.

The solvent preferably has a dielectric constant of 10 or more and 82 or less.
If the dielectric constant is less than 10, the hydrogen ion conductive polymer electrolyte contained in the catalyst ink is colloidal and therefore difficult to enter into the pores of carbon black, which may be disadvantageous in forming a three-phase interface. Because.
Further, if the dielectric constant exceeds 82, it is difficult to evaporate.

The concentration of the solid content in the catalyst ink is preferably 1% by mass or more and 20% by mass or less.
If the solid content is less than 1% by mass, a sufficient coating thickness of the catalyst layer may not be obtained. If the solid content exceeds 20% by mass, the dispersion stability tends to deteriorate.

The viscosity of the catalyst ink is preferably 0.5 cP or more and 2000 cP or less.
If it is less than 0.5 cP, a sufficient coating thickness of the catalyst layer may not be obtained, and if it is 2000 cP or more, the nozzle of the pressurized nozzle type emulsifier may be clogged.

By using a pressure nozzle type emulsifier for the dispersion treatment of the catalyst ink, the particle size of the particles in the catalyst ink can be reduced to the submicron level, and the ink preparation is continuously performed including the dispersion treatment. Therefore, the cost can be reduced in terms of process.
Furthermore, since it is medialess, there is an advantage that there is no fear that contamination and the like are mixed and the electrical characteristics of the catalyst layer are deteriorated.

As the pressure nozzle type emulsifier, for example, Nanomizer manufactured by Yoshida Kikai Kogyo Co., Ltd. can be used.
In the nanomizer, high pressure is applied to the generator portion and ink is dispersed using a shock wave to be discharged from the nozzle.
Further, any apparatus that generates a shock wave due to cavitation or turbulent flow generated in a liquid by collision between high-speed liquids such as a microfluidizer, genus, or an optimizer can be used.

The pressure of the pressure nozzle type emulsifier is preferably 100 MPa or more and 1500 MPa or less.
This is because if it is less than 100 MPa, sufficient dispersibility of the catalyst ink cannot be secured, and if it exceeds 1500 MPa, the catalyst ink is heated.

As a coating method of the catalyst ink prepared by the pressure nozzle type emulsifier, existing methods such as brush coating, brush coating, bar coater coating, knife coater coating, die coater coating, screen printing, and spray coating are used. The catalyst layer can be coated on the gas diffusion layer or hydrogen ion conductive polymer membrane, or coated on the transfer substrate and then transferred to the gas diffusion layer or hydrogen ion conductive polymer membrane Can be formed.

From the viewpoint of obtaining good gas diffusibility of the catalyst layer, the thickness of the catalyst layer is desirably 1 μm or more and 50 μm or less.

If the thickness of the catalyst layer is less than 1 μm, sufficient catalyst performance cannot be obtained.
On the other hand, if the thickness of the catalyst layer exceeds 50 μm, platinum exceeds the required amount, and platinum is used wastefully.

As a material for the transfer substrate, a TFE (tetrafluoroethylene) sheet or the like can be used.

According to the present invention, the particles in the prepared catalyst ink can control the median diameter in the range of 0.1 μm or more and 1.0 μm or less, and can maintain the highly dispersed state of the catalyst in the catalyst layer over a long period of time. .

Next, the front and back surfaces of the proton conductive membrane 3 (Nafion (trademark) (manufactured by DuPont)) having a thickness of 50 μm are sandwiched between the electrodes, and the pot is placed at a pressure of 40 kg / cm ² under 140 ° C. for 10 minutes. An electrode / membrane assembly was produced by press molding (FIG. 1B).

Next, two carbon separators 4 were laminated on the front and back surfaces of the electrode / membrane assembly (FIG. 1 (c)).

Next, two titanium current collectors 5 were laminated on the front and back surfaces of the carbon separator 4 (FIG. 1D).

Next, a heater 6 was arranged outside the titanium current collector 5 to assemble a fuel cell having an effective area of 5 cm ² (FIG. 1 (e)).

(Example 1)
(Manufacture of gas diffusion layer)
Carbon powder acetylene black (Denka Black, particle size 35 nm) manufactured by Denki Kagaku Kogyo Co., Ltd. and polytetrafluoroethylene (PTFE) aqueous dispersion (Daikin Kogyo Co., Ltd., D1) are mixed and dried. A water-repellent ink containing 20% by mass of PTFE and 80% by mass of acetylene black was prepared.
This water-repellent ink is coated on carbon paper (TGP060H, manufactured by Toray Industries, Inc.) as a base material for the gas diffusion layer, impregnated, and then heat treated at 300 ° C. using a hot air dryer to obtain a gas diffusion layer. It was.

(Manufacture of catalyst ink)
Platinum-supported carbon (Pt: 45% by mass supported) 10.2 g, distilled water 40.3 g, Nafion (trade name, manufactured by Dupont) 20.6% by weight water-alcohol solution (water: alcohol (weight ratio) = 20 : 60) 20.45 g, 140.53 g of n-propyl alcohol, and 0.40 g of a polymer dispersant (trade name: DA234, manufactured by Enomoto Kasei Co., Ltd.) were added, and the mixture was stirred at 1000 rpm for 60 minutes using a homogenizer.
Next, using a nanomizer manufactured by Yoshida Kikai Kogyo Co., Ltd., a 3-pass treatment was performed at a pressure of 1000 MPa to obtain catalyst ink A having a viscosity of 700 cP (25 ° C.).

(Catalyst layer formation-fuel cell production)
On the gas diffusion layer, the catalyst ink A was applied using a doctor blade so that the platinum coating amount was 0.50 mg.
This was heated and dried at 70 ° C. for 5 minutes to form an electrode.
Next, a Nafion ™ film having a thickness of 50 μm is sandwiched between two electrode layers, and is subjected to pot press molding at a pressure of 40 kg / cm ² at 140 ° C. for 10 minutes to produce an electrode / membrane assembly. did.
Next, the produced electrode / membrane assembly was sandwiched between two carbon separators and two titanium current collectors, and a heater was disposed on the outside thereof to assemble a fuel cell having an effective area of 5 cm ² .

The temperature of the fuel cell was kept at 50 ° C., hydrogen and oxygen were supplied at a humidity of 100% RH, and the voltage between terminals was measured at current densities of 0.5 A / cm ² and 1.0 A / cm ² .

Further, the temperature of the fuel cell was kept at 80 ° C., hydrogen and oxygen were supplied at a humidity of 100% RH, and the voltage across the terminals at current densities of 0.5 A / cm ² and 1.0 A / cm ² was measured.

The catalyst ink composition was filled in a 20 cc glass bottle and allowed to stand at room temperature for 1 week.
Then, 0.5 cc of each of the upper and lower liquids of the catalyst ink was sampled and dried on a hot plate at 95 ° C. for 10 minutes, and the presence or absence of particle sedimentation was determined by the change in the solid content concentration of the upper and lower liquids. confirmed.

In the storage stability evaluation, a state where there was no difference in the solid content concentration between the upper liquid and the lower liquid was evaluated as ◯.
Moreover, the state whose solid content concentration of a lower liquid is higher than the solid content concentration of an upper liquid was set as x.

(Example 2)
As a polymer dispersant, a catalyst having a viscosity of 730 cP (25 ° C.) was used in the same manner as in Example 1 except that DA234 (manufactured by Enomoto Kasei Co., Ltd.) was changed from 0.40 g to 0.50 g of Dimor N (manufactured by Kao Corporation). Ink B was prepared, and an electrode and a fuel cell were manufactured and evaluated.

(Example 3)
Except not performing stirring using a homogenizer, a catalyst ink C having a viscosity of 800 cP (25 ° C.) was prepared in the same manner as in Example 1, and an electrode and a fuel cell were manufactured and evaluated.

(Comparative Example 1)
A catalyst ink D having a viscosity of 850 cP (25 ° C.) was prepared in the same manner as in Example 1 except that the treatment with the nanomizer was not performed, and an electrode and a fuel cell were manufactured and evaluated.

(Comparative Example 2)
(The planetary ball mill was used without using the homogenizer and nanomizer.)
Platinum-supported carbon (Pt: 45% by mass supported) 10.2 g, distilled water 40.3 g, Nafion (trade name, manufactured by Dupont) 20.6% by weight water-alcohol solution (water: alcohol (weight ratio) = 20 : 60) 20.45 g, n-propyl alcohol 140.53 g, and polymer dispersing agent (trade name: DA234, manufactured by Enomoto Kasei Co., Ltd.) 0.40 g together with 150 g of 1 mm diameter zirconia balls for 300 cc zirconia cup And stirred at 250 rpm for 1 hour to prepare catalyst ink E having a viscosity of 710 cP (25 ° C.).
Otherwise, an electrode and a fuel cell were produced in the same manner as in Example 1 and evaluated.

(Comparative Example 3)
Platinum-supported carbon (Pt: 45% by mass supported) 10.2 g, distilled water 40.3 g, Nafion (trade name, manufactured by Dupont) 20.6% by weight water-alcohol solution (water: alcohol (weight ratio) = 20 : 60) 20.45 g, n-butyl acetate 135.24 g, and a polymer dispersant (trade name: DA234, manufactured by Enomoto Kasei Co., Ltd.) 0.40 g were added.
Otherwise, a catalyst ink F having a viscosity of 1000 cP (25 ° C.) was prepared in the same manner as in Example 1, and an electrode and a fuel cell were produced and evaluated.

(Comparative Example 4)
Platinum-supported carbon (Pt: 45% by mass supported) 10.2 g, distilled water 40.3 g, Nafion (trade name, manufactured by Dupont) 20.6% by weight water-alcohol solution (water: alcohol (weight ratio) = 20 : 60) 20.45 g and 140.53 g of n-propyl alcohol were added, and the mixture was stirred with a homogenizer at 1000 rpm for 60 minutes.
Next, three-pass treatment was performed with a pressure of 1000 MPa using a nanomizer manufactured by Yoshida Kikai Kogyo Co., Ltd.
Other than that was carried out similarly to Example 1, and prepared the catalyst ink G with a viscosity of 800 cP (25 degreeC), manufactured the electrode and the fuel cell, and evaluated.

Table 1 shows the storage stability of catalyst inks A to G prepared by various dispersion methods.
Only Comparative Example 4 in which no dispersant was added had insufficient storage stability.
Therefore, it was found that the storage stability of the catalyst ink was insufficient unless a polymer dispersant was added.

Table 2 shows the battery characteristics of batteries prepared using MEAs (membrane electrode assemblies) prepared using catalyst inks A to G prepared by various dispersion methods.

Examples 1 to 3 were confirmed to have sufficient battery characteristics under the temperature and humidity conditions of 50 ° C. and 100% RH and 80 ° C. and 100% RH.
However, in Example 3, since it was not processed with a homogenizer, the particle size of the catalyst ink before processing with the pressurized nozzle type emulsifier was coarse, and the nozzle of the pressurized nozzle type emulsifier was clogged.
Accordingly, it was more preferable to perform the treatment with a pressure nozzle type emulsifier after carrying out the homogenizer.

In the comparative example 1, the process by a pressurized nozzle type emulsifier is not performed.
Therefore, if the treatment by the pressure nozzle type emulsifier is not performed, the dispersibility of the catalyst ink is not sufficient and the battery characteristics are also deteriorated.

The battery of Comparative Example 2 has lower battery characteristics than the batteries of Examples 1 to 3.
Therefore, it was found that when the catalyst ink was prepared using a planetary ball mill, battery characteristics could not be obtained as compared with the case where a pressure nozzle type emulsifier was used.
In addition, when a planetary ball mill was used, all of the ink could not be used up.
In addition, the manufacturing process is lengthened, the productivity is lowered, and the cost is increased.

In Comparative Example 3, n-butyl acetate having a dielectric constant of 5.01 was used as a solvent instead of n-propyl alcohol having a dielectric constant of 20.1, but battery characteristics were not obtained.
When n-propyl alcohol was used, Nafion existing in the catalyst ink was in a uniform state and dissolved, but when butyl acetate was used, Nafion in the catalyst ink was in a colloidal state.
For this reason, it is considered that it is disadvantageous to form a three-phase interface at the interface between the fine platinum particles finely supported on the carbon particles and Nafion, and the battery characteristics are deteriorated.

In Comparative Example 4, compared with Examples 1 to 3, since the polymer dispersant was not added, the dispersibility of the catalyst ink was lowered and the battery characteristics were also lowered.

The catalyst ink of the battery electrode of the present invention exhibits excellent storage stability, and the catalyst electrode produced using the catalyst ink has excellent power generation characteristics, so that it can be used in the field of polymer electrolyte fuel cells. Available to:

It is sectional drawing which shows an example of the manufacturing method of the electrode of this invention, and a battery.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Base material 2 ... Catalyst ink layer 3 ... Proton conductive membrane 4 ... Separator 5 ... Current collector 6 ... Heater

Claims (12)

A step of producing a catalyst ink comprising at least a catalyst-supporting carbon, a hydrogen ion conductive polymer electrolyte, and a polymer dispersant dissolved in a solvent; a step of dispersing the catalyst ink; and a catalyst ink subjected to the dispersion treatment A method for producing an electrode, comprising a step of laminating a material on a substrate surface. The method for producing an electrode according to claim 1, wherein the polymer dispersant comprises at least one selected from the group consisting of a carboxylic acid, a carboxylate, and an amine. The polymer dispersant is 0.01% by mass or more and 20% by mass or less based on the total mass of the catalyst-supporting carbon and the hydrogen ion conductive polymer electrolyte, and the catalyst ink. The method for producing an electrode according to claim 2, wherein the concentration of the solid content therein is 1% by mass or more and 20% by mass or less. 4. The method for producing an electrode according to claim 1, wherein the dispersion-treated catalyst ink is produced using a pressure nozzle type emulsifier. The method for producing an electrode according to claim 4, wherein the pressure of the pressure nozzle type emulsifier is 100 MPa or more and 1500 MPa or less. The method for producing an electrode according to claim 1, wherein the catalyst ink has a viscosity of 0.5 cP (poise) or more and 2000 cP (poise) or less. The method for producing an electrode according to claim 1, wherein the solvent has a dielectric constant of 10 or more and 82 or less. 8. The method for manufacturing an electrode according to claim 1, wherein the base material is either a gas diffusion material or a hydrogen ion conductive polymer film. By applying the dispersion-treated catalyst ink on the transfer substrate and then transferring it to the base material, or by applying the dispersion-treated catalyst ink to the base material, The electrode manufacturing method according to claim 1, wherein the dispersion-treated catalyst ink is laminated on the surface of the substrate. An electrode manufactured by the manufacturing method according to claim 1. Laminating at least the electrode according to claim 10 on the front and back surfaces of the proton conducting membrane to form an electrode / membrane assembly, laminating a separator on the front and back surfaces of the electrode / membrane assembly, A method for producing a battery, comprising: a step of laminating a current collector on a separator surface; and a step of disposing a heater around the current collector. A battery manufactured by the manufacturing method according to claim 11.