WO2003088397A1

WO2003088397A1 - Fuel cell, electrode for fuel cell, and method for preparing the same

Info

Publication number: WO2003088397A1
Application number: PCT/JP2003/004819
Authority: WO
Inventors: Shin Nakamura; Yoshimi Kubo; Yuichi Shimakawa; Takashi Manako; Hidekazu Kimura; Hideto Imai; Sadanori Kuroshima; Tsutomu Yoshitake; Takeshi Obata
Original assignee: Nec Corporation
Priority date: 2002-04-17
Filing date: 2003-04-16
Publication date: 2003-10-23
Also published as: CN1643719A; TWI231620B; CN1324744C; TW200404382A

Abstract

A fuel cell, which comprises a solid polymer electrolyte film, a fuel electrode and/or an oxidizing agent electrode comprising a first solid polymer electrolyte and a catalytic substance and, provided between the electrolyte film and the electrode, an adhesive layer comprising a second polymer electrolyte; and the above fuel cell, wherein the solid polymer electrolyte film and the adhesive layer comprise the same solid polymer electrolyte. The fuel cell exhibits enhanced adhesion between the surface of the electrode and the solid polymer electrolyte film, which results in the improvement of cell characteristics and the improvement of the reliability thereof.

Description

TECHNICAL FIELD The present invention relates to a fuel cell, an electrode for a fuel cell, and a method for producing the same.

The present invention relates to a fuel cell, an electrode for a fuel cell, and a method for producing the same. Background art

A polymer electrolyte fuel cell is configured by using a solid polymer electrolyte membrane such as a perfluorosulfonate membrane as an electrolyte, and joining a fuel electrode and a catalyst electrode to both sides of the membrane. This is a device that supplies oxygen to the hydrogen and oxidizer electrodes and generates power by an electrochemical reaction.

The following electrochemical reaction occurs in each electrode.

Fuel _{^{electrode: H 2 → 2 H + +}} 2 e - oxidant _{electrode: l / 2 0 2 + 2} H + + 2 e- → H 2 0

By this reaction, the polymer electrolyte fuel cell can obtain a high output of 1 A / cm ² or more at normal temperature and normal pressure.

The fuel electrode and the oxidant electrode are provided with a mixture of carbon particles carrying a catalyst metal and a solid polymer electrolyte. In general, the mixture is applied to an electrode substrate such as a force pump to be a fuel gas diffusion layer. A fuel cell is constructed by sandwiching a solid polymer electrolyte membrane between these two electrodes and thermocompression bonding.

In the fuel cell having this configuration, the hydrogen gas supplied to the fuel electrode passes through the pores in the electrode and reaches the catalyst, and emits electrons to become hydrogen ions. The emitted electrons are led to the external circuit through the carbon particles and the solid electrolyte in the fuel electrode, and flow into the oxidizer electrode from the external circuit. On the other hand, hydrogen ions generated at the fuel electrode pass through the solid polymer electrolyte in the fuel electrode and the solid polymer electrolyte membrane disposed between the two electrodes, reach the oxidizer electrode, and are supplied to the oxidizer electrode. The element reacts with the electrons flowing from the external circuit to produce water as shown in the above reaction formula. As a result, in the external circuit, electrons flow from the fuel electrode to the oxidizer electrode, and power is extracted.

In order to improve the characteristics of the fuel cell configured as described above, it is important that the adhesion between the electrode and the solid polymer electrolyte membrane be good. That is, it is required that the conductivity of hydrogen ions generated by the electrode reaction be high at the interface between the two. Poor interfacial adhesion reduces the conductivity of hydrogen ions and increases electrical resistance, causing a reduction in battery efficiency.

The fuel cell using hydrogen as a fuel has been described above. In recent years, research and development of a fuel cell using an organic liquid fuel such as methanol has been actively conducted.

Fuel cells that use organic liquid fuel include those that reform organic liquid fuel into hydrogen gas and use it as fuel, and those that do not reform organic liquid fuel, such as direct methanol fuel cells. A fuel supply system directly to a fuel electrode is known.

Above all, a fuel cell that supplies organic liquid fuel directly to the anode without reforming it does not require a device such as a reformer because it has a structure that supplies organic liquid fuel directly to the anode. Therefore, there is an advantage that the configuration of the battery can be simplified and the entire device can be reduced in size. In addition, compared with gaseous fuels such as hydrogen gas and hydrocarbon gas, organic liquid fuels have the feature that they can be transported easily and safely.

Generally, in a fuel cell using an organic liquid fuel, a solid polymer electrolyte membrane made of a solid polymer ion exchange resin is used as an electrolyte. Here, in order for the fuel cell to function, it is necessary for hydrogen ions to move from the fuel electrode to the oxidant electrode in the membrane, but it is known that the movement of the hydrogen ions is accompanied by the movement of water. The membrane must contain a certain amount of water.

However, when an organic liquid fuel such as methanol having a high affinity for water is used, the organic liquid fuel diffuses into the solid polymer electrolyte membrane containing water and further reaches the oxidant electrode ( Crossover). This crossover is originally The organic liquid fuel, which should provide electrons at the fuel electrode, is oxidized on the oxidant electrode side and is not used effectively as fuel, causing a decrease in voltage, output, and fuel efficiency. From the viewpoint of solving such a crossover problem, a polymer having a low water content should be selected as the material of the solid polymer electrolyte membrane to suppress the diffusion of organic liquid fuel such as methanol with water. desired. However, for the catalyst layer on the electrode surface in contact with the electrolyte membrane, it is important to efficiently move the organic liquid fuel as fuel from the electrode layer and supply a large amount of hydrogen ions. That is, it is desirable that the catalyst layer on the electrode surface is permeable to the organic liquid fuel, and the electrolyte membrane is permeable to the organic liquid fuel. In order to achieve this, the polymer constituting the catalyst layer on the electrode surface should be a polymer having a high water content and high permeability to organic liquid fuel, and the polymer constituting the solid polymer electrolyte membrane should be used. It is considered to be preferable to use a material having a low water content and a property of low permeability of organic liquid fuel.

Japanese Patent Application Laid-Open No. 2001-167775 discloses a technique relating to an ion-conductive film which makes it possible to suppress the crossover of methanol while maintaining the ion conductivity. Here, the surface layer of an ion conductive film having a basic structure of a fluororesin such as Nafion (registered trademark) is modified by electron beam irradiation or the like so that the conductivity becomes lower than the internal conductivity. ing.

However, when the material of the electrode surface catalyst layer and the material of the solid polymer electrolyte membrane are made of different materials as described above, generally, sufficient adhesion cannot be obtained, and the interface between the electrode surface and the solid polymer electrolyte membrane is generally not obtained. May cause peeling. When such peeling occurs, the electrical resistance at the interface increases, causing a decrease in the reliability of the battery performance. Also, as described in JP-A-2001-1677755, when the surface layer of the ion conductive film is modified, the surface of the ion conductive film at the time of swelling is also improved. There is a problem that the strength is increased and the adhesion to the electrode surface catalyst layer is deteriorated.

In view of the above circumstances, an object of the present invention is to improve the adhesion at the interface between the electrode surface and the solid polymer electrolyte membrane, thereby improving battery characteristics and battery reliability. Another object of the present invention is to suppress the crossover of the organic liquid fuel while maintaining good hydrogen ion conductivity and permeability of the organic liquid fuel on the electrode surface. Disclosure of the invention

As a solid polymer electrolyte of a fuel cell, a solid polymer electrolyte having high hydrogen ion conductivity represented by Naphion (registered trademark) is generally used. The high hydrogen ion conductivity of the solid polymer electrolyte is caused by the polymer electrolyte containing a large amount of water. On the other hand, the large amount of water contains an organic liquid such as methanol. The body fuel will be easily dissolved in water to promote crossover.

In order to suppress crossover, the present inventor has proposed a polymer material having a lower organic liquid fuel permeability than naphion or the like as a fuel electrode, an oxidizer electrode, and a solid polymer electrolyte constituting a solid polymer electrolyte membrane. A direct methanol fuel cell was fabricated using the method described above and evaluated. However, the characteristics of this fuel cell were lower than those of a conventional cell using naphion. This is thought to be due to a decrease in methanol permeability and hydrogen ion conductivity at the fuel electrode. The fuel electrode of the fuel cell has a structure in which carbon particles carrying a catalyst and a solid polymer electrolyte as a binder are provided in a mixed form, and a solid polymer electrolyte is interposed between the catalysts. It has become. For this reason, in order for methanol, hydrogen, and electrons to move smoothly on the electrode surface, the solid polymer electrolyte serving as these transmission paths has high liquid fuel permeability such as methanol and excellent hydrogen ion conductivity. It is necessary to be. In the battery with the above structure, it is considered that good battery characteristics could not be obtained because the solid polymer electrolyte did not sufficiently satisfy these performances.

Next, in order to increase the efficiency of the catalytic reaction at the fuel electrode, the present inventors used naphthion as a solid polymer electrolyte on the electrode surface, and used a solid polymer electrolyte membrane as an organic liquid fuel permeation rather than naphthion or the like. An attempt was made to fabricate a direct methanol fuel cell using a low polymer material. However, the bonding between the fuel electrode and the solid polymer electrolyte membrane was insufficient, and a battery that could withstand the evaluation was obtained. I couldn't do it.

Based on the results of the preliminary experiments described above, as a result of further studies, the present inventors have found that by effectively utilizing a plurality of types of solid polymer electrolytes, the adhesion at the interface between the electrode surface and the solid polymer electrolyte membrane is improved. The inventors have found that the properties can be effectively improved, and have completed the present invention. According to the present invention, a first solid polymer electrolyte and a catalyst electrode containing a catalyst substance, a solid polymer electrolyte membrane, and a second polymer provided between the catalyst electrode and the solid polymer electrolyte membrane And a bonding layer containing an electrolyte.

Here, the adhesive layer and the solid polymer electrolyte membrane may be in contact with or separated from each other. If a configuration in which these are in contact with each other is employed, the adhesion at the interface between the adhesive layer and the solid polymer electrolyte membrane can be reliably improved.

Further, the adhesive layer and the catalyst electrode may be in contact with or separated from each other. If a configuration in which these are in contact with each other is adopted, the adhesion at the interface between the adhesive layer and the catalyst electrode can be reliably improved. The “catalyst electrode” in the present invention is an electrode containing a catalyst, and is used as a generic term including a fuel electrode and an oxidant electrode. The first solid polymer electrolyte on the catalyst electrode surface serves to electrically connect the catalyst-supporting carbon particles and the solid polymer electrolyte membrane on the electrode surface and to allow the organic liquid fuel to reach the catalyst surface. Hydrogen ion conductivity and water mobility are required. Further, the fuel electrode is required to be permeable to organic liquid fuel such as methanol, and the oxidant electrode is required to be permeable to oxygen. The first solid polymer electrolyte satisfies these requirements, and materials having excellent hydrogen ion conductivity and organic liquid fuel permeability such as methanol are preferably used.

On the other hand, the solid polymer electrolyte membrane separates the fuel electrode and the oxidizer electrode, and has a role of moving hydrogen ions between the two.In addition, the liquid fuel moves from the fuel electrode to the oxidizer electrode. That is, it is desired to have the property of suppressing the crossover of the organic liquid fuel. As described above, the fuel electrode, the agent electrode, and the solid polymer electrolyte membrane have different properties required from each other, and therefore, it is desirable that they be made of different materials. However, It is generally difficult to ensure sufficient adhesion at the interface between different materials. Therefore, the present invention provides an adhesive layer between the catalyst electrode and the solid polymer electrolyte membrane to ensure sufficient adhesion between the electrode and the solid polymer electrolyte membrane even when a material suitable for the electrode and the solid polymer electrolyte membrane is selected. It can be.

That is, the catalyst electrode according to the present invention has a configuration in which the electrode surface includes the first solid polymer electrolyte, the adhesive layer includes the second solid polymer electrolyte, and the first solid polymer electrolyte causes hydrogen on the electrode surface. In addition to ensuring smooth movement of ions and liquid fuel, the second solid polymer electrolyte makes the interface between the catalyst electrode and the solid polymer electrolyte membrane tightly adhered. According to the present invention, by adopting such a configuration, it is possible to stably achieve good battery efficiency over a long period of time while suppressing an increase in electrical resistance at the interface between the catalyst electrode and the solid polymer electrolyte membrane. can do.

The adhesive layer in the present invention does not need to be formed over the entire surface between the solid polymer electrolyte membrane and the catalyst electrode, but may be formed at least partially between them. Further, the adhesive layer may include the first solid polymer electrolyte. In this case, the content of the first solid polymer electrolyte in the adhesive layer may have a distribution along the direction from the catalyst electrode to the solid polymer electrolyte membrane. For example, a configuration in which the adhesive layer includes the first solid polymer electrolyte on the side in contact with the catalyst electrode and does not include the first solid polymer electrolyte on the side in contact with the solid polymer electrolyte membrane can be employed. At the same time, the adhesive layer does not include the second solid polymer electrolyte on the side in contact with the catalyst electrode, and includes the second solid polymer electrolyte on the side in contact with the solid polymer electrolyte membrane. it can. This can improve the adhesion between the adhesive layer and the catalyst electrode, and between the adhesive layer and the solid polymer electrolyte membrane.

Further, the adhesive layer may include a catalytic material. In this case, the content of the catalyst substance in the adhesive layer may have a distribution along the direction from the catalyst electrode to the solid polymer electrolyte membrane. For example, it is possible to adopt a configuration in which the adhesive layer contains a catalytic substance on the side in contact with the catalyst electrode and does not contain a catalytic substance on the side in contact with the solid polymer electrolyte membrane. Adhesive layer contains catalytic material With such a configuration, the electron conductivity can be improved even in the adhesive layer. Here, the second solid polymer electrolyte can have higher adhesion to the solid polymer electrolyte membrane than the first solid polymer electrolyte. Further, the second solid polymer electrolyte can be made of a solid polymer electrolyte constituting a solid polymer electrolyte membrane or a derivative thereof. By doing so, good adhesion is developed between the first solid polymer electrolyte and the solid polymer electrolyte membrane via the second solid polymer electrolyte constituting the adhesive layer.

In the fuel cell according to the present invention, an organic liquid fuel may be supplied to the catalyst electrode. That is, a so-called direct type fuel cell can be obtained. Here, the organic liquid fuel can be, for example, methanol. Direct-type fuel cells have the advantages of high cell efficiency, space savings because no reformer is required, and other advantages.On the other hand, crossover of organic liquid fuels such as methanol is a problem. . According to the present invention, it is possible to stably achieve good battery efficiency over a long period of time by suppressing an increase in electrical resistance at the interface between the catalyst electrode and the solid polymer electrolyte membrane while solving such a problem of crossover. can do.

Further, according to the present invention, there is provided an electrode layer containing a catalyst substance and a first solid polymer electrolyte, and an adhesive layer containing a second solid polymer electrolyte formed on the electrode layer. An electrode for a fuel cell is provided.

According to the present invention, the hydrogen ion conductivity and the liquid fuel permeability on the surface of the catalyst electrode are improved by the first solid polymer electrolyte, and the catalyst electrode and the solid polymer electrolyte membrane are formed by the second solid polymer electrolyte. Can be firmly joined. In the conventional catalyst electrode, the solid electrolyte constituting the electrode surface had to satisfy both electrode performance and interfacial adhesion at the same time. In the present invention, however, the first solid height The molecular electrolyte may improve the electrode performance, and the second solid polymer electrolyte may improve the interfacial adhesion. Therefore, it is possible to stably realize both electrode performance and interfacial adhesion, which are difficult to achieve with a single type of solid polymer electrolyte. Furthermore, according to the present invention, there is provided a method for producing an electrode for a fuel cell in which a catalyst layer and an adhesive layer are formed on a substrate in this order, comprising: conductive particles carrying a catalyst metal; and a first solid polymer electrolyte. Forming a catalyst layer by applying a first coating solution containing particles containing the first solid polymer electrolyte to a substrate; and a second solid polymer electrolyte comprising a polymer different from the first solid polymer electrolyte. A step of applying a second coating solution containing particles containing the above on a catalyst layer to form the adhesive layer, the method for producing an electrode for a fuel cell provided.

According to this production method, the first coating solution containing particles containing the first solid polymer electrolyte is applied to the substrate to form a catalyst layer, and then different from the first solid polymer electrolyte. A second coating solution containing particles containing a second solid polymer electrolyte made of a polymer is applied on the catalyst layer to form an adhesive layer. Therefore, a layer of particles containing the second solid polymer electrolyte is formed on the layer of particles containing the first solid polymer electrolyte, and excellent adhesion between the two is exhibited. The reason why good adhesion is obtained by adopting such a method is not always clear, but since the catalyst layer is composed of a layer of particles, moderate irregularities are generated on the surface thereof, and the adhesive layer is formed. This is presumed to be due to the fact that the contact area between the particles increases and adsorption or binding easily occurs. Here, if the solid polymer electrolyte membrane is configured to include the second solid polymer electrolyte, the adhesion between the adhesive layer and the solid polymer electrolyte membrane can also be improved.

The coating solution may have a structure in which particles containing the first solid polymer electrolyte or particles containing the second solid polymer electrolyte are dispersed in the coating solution. By doing so, workability during coating and production stability can be improved.

Further, according to the present invention, after the fuel cell electrode is obtained by the above-described method for producing a fuel cell electrode, the fuel cell electrode and the solid polymer electrolyte are contacted with the adhesive layer and the solid polymer electrolyte membrane in contact with each other. A method for manufacturing a fuel cell, the method including a step of thermocompression bonding with a porous membrane.

According to this production method, the adhesive layer can be stably formed in a simple step, and a fuel cell having good adhesion between the catalyst electrode and the solid polymer electrolyte membrane can be stably obtained.

According to the present invention, a solid polymer electrolyte membrane, and the solid polymer electrolyte membrane sandwiched between the A method for manufacturing a fuel cell having a pair of electrodes having a medium layer formed thereon, comprising: applying a first coating liquid containing a catalyst substance and particles containing a first solid polymer electrolyte to a substrate. Forming a catalyst layer by applying a second coating solution containing particles containing a second solid polymer electrolyte composed of a polymer different from the first solid polymer electrolyte to a solid polymer electrolyte membrane. A fuel cell comprising: a step of forming an adhesive layer by coating; and a step of thermocompression bonding the electrode and the solid polymer electrolyte membrane in a state where the catalyst layer and the adhesive layer are in contact with each other. A method is provided.

In the present invention, the second solid polymer electrolyte preferably has a lower permeability of the organic liquid fuel than the first solid polymer electrolyte. By doing so, it becomes possible to obtain the adhesion to the solid polymer electrolyte membrane while securing the organic liquid fuel permeability and the hydrogen ion conductivity in the catalyst electrode. To achieve this, for example, the following configuration may be used.

(i) The second solid polymer electrolyte has a lower water content than the first solid polymer electrolyte.

(11) The first solid polymer electrolyte and the second solid polymer electrolyte each include a proton acid group, and the second solid polymer electrolyte includes a first solid polymer electrolyte. The proton acid group content density is lower than the molecular electrolyte. Here, the protonic acid group is, for example, one or more polar groups selected from the group consisting of a sulfone group, a carbonyl group, a phosphoric acid group, a phosphonic acid group and a phosphinic acid group.

Further, in the present invention, the first solid polymer electrolyte may be constituted by a polymer containing fluorine. Further, in the present invention, the second solid polymer electrolyte may be formed of a polymer containing no fluorine. Further, in the present invention, the second solid polymer electrolyte described above may be constituted by a polymer containing an aromatic. The measurement of the resin content and the catalyst content in the present invention is performed by, for example, performing secondary ion mass spectrometry (SIMS) while sputtering the layer structure to be measured from the surface. Can be. As described above, according to the present invention, since the adhesive layer is provided between the catalyst electrode and the solid polymer electrolyte membrane, good adhesion between the solid polymer electrolyte membrane and the electrode can be obtained. Therefore, the adhesion at the interface between the electrode surface and the solid polymer electrolyte membrane can be increased, and the battery characteristics can be improved and the reliability of the battery can be improved. Further, crossover of the organic liquid fuel can be suppressed while maintaining good hydrogen ion conductivity and organic liquid fuel permeability on the electrode surface.

The above and other objects, aspects and advantages of the present invention will become more apparent from the following description. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a sectional view schematically showing the structure of an example of the fuel cell of the present invention.

FIG. 2 is a cross-sectional view schematically showing a fuel electrode, an oxidant electrode, and a solid polymer electrolyte membrane in an example of the fuel cell of the present invention.

FIG. 3 is a diagram schematically showing a fuel electrode and a solid polymer electrolyte membrane in a fuel cell according to an example of the present invention.

FIG. 4 is a cross-sectional view showing the adhesive layer in the embodiment of the present invention in detail.

FIG. 5 is a diagram schematically showing a fuel electrode and a solid polymer electrolyte membrane of a fuel cell according to an example of the present invention, and an adhesive layer interposed therebetween. .

FIG. 6 is a diagram schematically showing a fuel electrode and a solid polymer electrolyte membrane of a fuel cell according to an example of the present invention, and an adhesive layer interposed therebetween.

FIG. 7 is a diagram schematically showing a fuel electrode and a solid polymer electrolyte membrane of a fuel cell according to an example of the present invention, and an adhesive layer interposed therebetween. BEST MODE FOR CARRYING OUT THE INVENTION

A fuel cell according to the present invention includes: a catalyst electrode including a first solid polymer electrolyte and a catalyst substance; An adhesive layer containing the second polymer electrolyte is provided between the solid polymer electrolyte membrane. In the manufacturing process, the adhesive layer may be formed on the surface of the catalyst electrode or the solid polymer electrolyte membrane and then bonded to the catalyst electrode and the solid polymer electrolyte membrane, or the catalyst electrode and the solid polymer electrolyte membrane may be used. In a state where a sheet made of the second solid polymer electrolyte is disposed between the membrane and the membrane, these may be joined by thermocompression bonding or the like.

The catalyst electrode of the present invention contains a catalyst substance and a first solid polymer electrolyte. Specifically, for example, a configuration in which a catalyst layer containing a catalyst substance and a first solid polymer electrolyte is formed on a substrate such as a force pump or the like can be used. Here, the catalyst material includes a catalyst metal and conductive particles carrying the catalyst metal. Here, carbon particles or the like are used as the conductive particles. The first solid polymer electrolyte has a role of immobilizing the conductive particles on the base and electrically connecting the conductive particles to the solid polymer electrolyte membrane.

The adhesive layer in the present invention contains the second solid polymer electrolyte. As a component other than the second solid polymer electrolyte, conductive particles such as a catalyst metal and carbon particles carrying the catalyst metal may be included. Since the adhesive layer contains the catalytic metal and the conductive particles as described above, the organic liquid fuel is consumed in the adhesive layer, and an electrode reaction occurs, so that the electron conductivity of the adhesive layer can be improved. The adhesive layer in the present invention may include a solid polymer electrolyte other than the second solid polymer electrolyte, such as the first solid polymer electrolyte.

[Embodiment]

Hereinafter, the first to third embodiments of the present invention will be described in detail.

(First embodiment)

As shown in FIG. 1, in the fuel cell of this embodiment, the electrode-electrolyte assembly 101 is composed of a fuel electrode 102, an oxidant electrode 108, and a solid polymer electrolyte membrane 114. . The fuel electrode 102 includes a substrate 104 and a catalyst layer 106. The oxidant electrode 108 is composed of a base 110 and a catalyst layer 112. In addition, between the solid polymer electrolyte membrane 114 and the fuel electrode 102, An adhesive layer 161 is provided between the polymer electrolyte membrane 114 and the oxidant electrode 108, respectively. The plurality of electrode-electrolyte assemblies 101 are electrically connected via the fuel electrode side separator 120 and the oxidizer electrode side separator 122 to manufacture the fuel cell 100. .

The fuel electrode 102 and the oxidant electrode 108 have a configuration including a catalyst layer 106 and a catalyst layer 112 each containing a catalyst and a first solid polymer electrolyte. The solid polymer electrolyte membrane 114 is made of a second solid polymer electrolyte. The adhesive layer 161 contains the second solid polymer electrolyte. Specific materials constituting the first and second solid polymer electrolytes will be described later. In the fuel cell 100 configured as described above, the fuel electrode 102 of the electrode-electrolyte assembly 101 is supplied with the fuel 124 through the fuel electrode side separator 120. Is done. The oxidizer electrode 108 of each electrode-electrolyte assembly 101 is supplied with an oxidizer 126 such as air or oxygen through the oxidizer electrode side separator 122. .

The solid polymer electrolyte membrane 114 has a role of separating the fuel electrode 102 from the oxidant electrode 108 and also has a role of transferring hydrogen ions and water molecules between the two. For this reason, it is preferable that the solid polymer electrolyte membrane 114 be a membrane having high conductivity of hydrogen ions. It is also preferable that the material is chemically stable and has high mechanical strength. Examples of the material constituting the solid polymer electrolyte membrane 114 include an organic polymer having a polar group such as a strong acid group such as a sulfone group, a phosphate group, a phosphone group, or a phosphine group, or a weak acid group such as a lipoxyl group. It is preferably used. Examples of such organic polymers include aromatic-containing polymers such as sulfonated poly (4-phenoxybenzoyl_1,4-phenylene) and alkyl sulfonated polybenzoimidazole; polystyrene sulfonate copolymer Copolymers such as polyvinyl sulfonic acid copolymers, cross-linked alkyl sulfonic acid derivatives, fluorine resin skeletons and fluorine-containing polymers composed of sulfonic acid; acrylamides such as acrylamide 2-methylpropane sulfonic acid; A copolymer obtained by copolymerizing an acrylate such as butyl methacrylate; a sulfone group-containing perfluorocarbon (Naphion (registered trademark, manufactured by Dupont), aciplex (manufactured by Asahi Kasei Corporation)); a lipoxyl group-containing Perfluorocarbon (Flemion (registered trademark) S film (Asahi Glass Co., Ltd.) )); And the like. Of these, when aromatic-containing polymers such as sulfonated poly (4-phenoxybenzoyl-1,4-phenylene) and alkylsulfonated polybenzoimidazole are selected, organic liquid fuel Transmission can be suppressed, and a decrease in battery efficiency due to crossover can be suppressed.

In addition, a crosslinkable substituent, for example, a bier group, an epoxy group, an acrylic group, a methacryl group, a cinnamoyl group, a methylol group, an azide group, or a naphthoquinone diazide group is appropriately introduced into the above-described polymer. A polymer that has been crosslinked by irradiating it with radiation in a molten state can also be used.

FIG. 2 is a cross-sectional view schematically showing the structure of the fuel electrode 102, the oxidizer electrode 108, the solid polymer electrolyte membrane 114, and the adhesive layer 161. As shown in the figure, the fuel electrode 102 and the oxidizer electrode 108 in the present embodiment have a catalyst layer 106, which is a membrane containing carbon particles carrying a catalyst and fine particles of a solid polymer electrolyte, and a catalyst. The structure is such that the layer 112 is formed on the substrate 104 and the substrate 110. The substrate surface may be subjected to a water-repellent treatment.

As the substrate 104 and the substrate 110, a porous substrate such as carbon paper, molded carbon fiber, sintered carbon, sintered metal, or foamed metal can be used. In addition, a water repellent such as polytetrafluoroethylene can be used for the water repellent treatment of the substrate.

Examples of the catalyst for the anode 102 include platinum, platinum t-ruthenium, gold, rhenium, and the like, rhodium, palladium, iridium, osmium, ruthenium, rhenium, gold, silver, nickel, cobalt, lithium, lanthanum, and the like. Examples include strontium and yttrium. On the other hand, as the catalyst for the oxidant electrode 108, the same catalyst as the catalyst for the fuel electrode 102 can be used, and the above-mentioned exemplified substances can be used. The catalysts for the fuel electrode 102 and the oxidant electrode 108 may be the same or different.

The carbon particles supporting the catalyst include acetylene black (Denka Black (registered trademark, manufactured by Denki Kagaku Kogyo), XC72 (Vu1can), etc.), Ketjen Black, carbon nanotubes, and carbon nanohorns. And the like. The size of the carbon particles is For example, it is set to 0.01 to 0.1 μπι, preferably to 0.02 to 0.06 m.

The solid polymer electrolyte constituting the fuel electrode 102 or the oxidizer electrode 108 is configured to include at least the first solid polymer electrolyte. In addition, the solid polymer electrolyte constituting the fuel electrode 102 or the oxidizer electrode 108 may include a second solid polymer electrolyte. Here, both the fuel electrode 102 and the oxidizer electrode 108 may be configured to include the first and second solid polymer electrolytes, or the fuel electrode 102 and the oxidizer electrode 108 Either one of them may be configured to include the first and second solid polymer electrolytes.

The first solid polymer electrolyte constituting the fuel electrode 102 and the oxidant electrode 108 electrically connects the carbon particles carrying the catalyst and the solid polymer electrolyte membrane 114 on the electrode surface. It is required to have good hydrogen ion conductivity and water mobility.

In 102, permeability of organic liquid fuel such as methanol is required, and in oxidant electrode 108, oxygen permeability is required. The first solid polymer electrolyte satisfies such demands, and materials excellent in hydrogen ion conductivity and organic liquid fuel permeability such as methanol are preferably used. Specifically, an organic polymer having a polar group such as a strong acid group such as a sulfone group or a phosphoric acid group or a weak acid group such as a carbonyl group is preferably used. Examples of such organic polymers include sulfone group-containing perfluorocarbon (Nafion (registered trademark, manufactured by Dupont), aciplex (manufactured by Asahi Kasei Corporation), etc.); S film (manufactured by Asahi Glass Co., Ltd.); polystyrene sulfonic acid copolymer, polypinyl sulfonic acid copolymer, cross-linked alkyl sulfonic acid derivative, fluorine resin skeleton and fluorine-containing polymer composed of sulfonic acid And copolymers obtained by copolymerizing acrylamides such as acrylamide-12-methylpropanesulfonic acid and acrylates such as n-butyl methacrylate; and the like. Examples of the polymer to which the polar group is bonded include amines such as a polybenzimidazole derivative, a polybenzoxazole derivative, a crosslinked polyethyleneimine, a polysilamine derivative, and a polyethylaminoethyl polystyrene. Substituted polystyrene, getylaminoethyl polymer Resins having nitrogen or hydroxyl groups such as nitrogen-substituted polyacrylates such as phenols; hydroxyl-containing polyacryl resins represented by silanol-containing polysiloxanes and hydroxyethyl polymethyl acrylate; hydroxyl-containing polystyrenes represented by para-hydroxypolystyrene Resins; etc. can also be used. Of these, from the viewpoint of ion conductivity and the like, sulfone group-containing perfluorocarbons (Nafion (registered trademark, manufactured by DuPont), acylplex (Asahi Kasei Corporation), etc.), and carboxyl group-containing perfluorocarbon Carbon (such as Flemion (registered trademark) S film (manufactured by Asahi Glass Co., Ltd.)) is preferably used.

In addition, a crosslinkable substituent, for example, a vinyl group, an epoxy group, an acrylic group, a methyl group, a cinnamoyl group, a methylol group, an azide group, or a naphthoquinone diazide group may be appropriately introduced into the above-described polymer. Is also good.

The second solid polymer electrolyte constituting the adhesive layer 161 in FIG. 1 plays a role in improving the adhesion between the electrode surface and the solid polymer electrolyte membrane 114. It is preferable to use a material having good adhesion to the film 114. For example, when the solid polymer electrolyte membrane 114 is composed of an organic polymer, as the second solid polymer electrolyte, a polymer having a structure similar to that of the organic polymer, polarity, wettability, SP value, etc. By selecting a polymer having similar physical properties, the adhesion between the electrode and the solid polymer electrolyte membrane 114 can be improved. For example, when a polymer containing no fluorine is used as the material of the solid polymer electrolyte membrane 114, it is preferable to select a polymer containing no fluorine as the second solid polymer electrolyte. When an aromatic polymer is used as the material of the solid polymer electrolyte membrane 114, it is preferable to select an aromatic polymer as the second solid polymer electrolyte. Further, the adhesive layer 161 can also be composed of a polymer in which a polymer having a crosslinkable substituent introduced therein is crosslinked by, for example, irradiating radiation in a molten state.

Here, from the viewpoint of suppressing crossover, it is preferable that both the solid polymer electrolyte membrane 114 and the second solid polymer electrolyte be made of a material having low permeability to organic liquid fuel. For example, sulfonated poly (4-phenoxybenzoyl _1,4-phenylene), alk It is preferable to use an aromatic condensed polymer such as rusulfonated polybenzoimidazole. Further, the solid polymer electrolyte membrane 114 and the second solid polymer electrolyte should have, for example, a swelling property with methanol of 50% or less, more preferably 20% or less (swelling property with respect to 70 vol% MeOH solution). Good. By doing so, particularly good interfacial adhesion and proton conductivity can be obtained.

The first solid polymer electrolyte in the fuel electrode 102 and the oxidant electrode 108 may be the same or different.

As the fuel of the fuel cell according to the present embodiment, a liquid organic fuel or a hydrogen-containing gas can be used. Among them, when the liquid organic fuel is used, the cell efficiency can be improved while suppressing the crossover of the liquid fuel, and the effect of the present invention is more remarkably exhibited. The method for producing the electrode-electrolyte assembly in the present embodiment is not particularly limited, and for example, it can be produced as follows.

First, a catalyst is supported on carbon particles. This step can be performed by a commonly used impregnation method. Next, the catalyst-supported carbon particles and the first solid polymer electrolyte particles are dispersed in a solvent to form a paste, which is then applied to a substrate and dried to form the catalyst layer 106 or the catalyst layer 112. The formed fuel electrode 102 and oxidant electrode 108 can be produced. Here, the particle size of the carbon particles is, for example, 0.001 to 0.1m. The particle size of the catalyst particles is, for example, 0.1 ηπ! 〜100 nm. The particle size of the first and second solid polymer electrolyte particles is, for example, 0.05 to 100 iirn. The carbon particles and the solid polymer electrolyte particles are used, for example, in a weight ratio of 1: 5 to 40: 1. Also, ぺ

— The weight ratio of water to solute in the strike is, for example, about 1: 2 to 10: 1. The method of applying the paste to the substrate is not particularly limited, and for example, methods such as brush coating, spray coating, and screen printing can be used. The cost is about ΐμπ! It is applied with a thickness of ~ 2mm. After applying the paste, the paste is dried by heating at a heating temperature and heating time according to the first solid polymer electrolyte to be used. The heating temperature and heating time depend on the material used. For example, the heating temperature may be 100 ° C. to 250 ° C., and the heating time may be 30 seconds to 30 minutes.

The solid polymer electrolyte membrane 114 in the present invention can be manufactured by using an appropriate method according to the material to be used. For example, it can be obtained by casting and drying a liquid in which an organic polymer material is dissolved or dispersed in a solvent, on a peelable sheet of polytetrafluoroethylene or the like.

Next, an adhesive layer 16 1 is formed. The adhesive layer 161 is formed by coating the coating solution in which the second solid polymer electrolyte is dissolved or dispersed on the catalyst layer 106 or the catalyst layer 112, and / or the solid polymer electrolyte membrane 111. It can be formed by coating and drying on the surface of 4. When the coating liquid is applied onto the solid polymer electrolyte membrane 114, this step is performed on both the front and back surfaces of the solid polymer electrolyte membrane 114. In this case, for example, after applying the above coating solution to one surface of the solid polymer electrolyte membrane 114, the surface is urged with a peelable sheet of polytetrafluoroethylene or the like to obtain a solid polymer electrolyte membrane. A method of applying the above-mentioned coating liquid to the other surface of 114 can be adopted. Thus, a solid polymer electrolyte membrane 114 having the adhesive layers 161 formed on both surfaces can be obtained.

In the present embodiment, the adhesive layer 16 1 is formed between the solid electrolyte membrane 114 and the fuel electrode 102 and between the solid and solid electrolyte membrane 114 and the oxidant electrode 108. , But may be provided in any one of them. Further, the adhesive layer 161 does not need to be formed over the entire surface of these regions, but may be formed only partially on the above-described region. For example, the adhesive layer 161 may be formed in an island shape. The thickness of the adhesive layer 161 is appropriately selected, for example, from the range of 0.1] ^ to 20111.

The solid polymer electrolyte membrane 114 produced as described above is sandwiched between the fuel electrode 102 and the oxidant electrode 108 and hot-pressed to obtain an electrode-electrolyte assembly. At this time, the surfaces of both electrodes where the catalyst is provided and the solid polymer electrolyte membrane 114 are opposed to each other with the adhesive layer 161 interposed therebetween. Hot pressing conditions are selected according to the material. For example, the first solid polymer electrolyte Or a temperature exceeding the softening temperature or the glass transition temperature of the second solid polymer electrolyte. Specifically, for example, the temperature is set to 100 to 250 ° C., the pressure is set to 5 to: L 0 kgf / cm ² , and the time is set to 10 to 300 seconds.

In FIG. 2, since the second solid polymer electrolyte constituting the adhesive layer 161 is common to the material of the solid polymer electrolyte membrane 114, the interface between the electrode and the solid polymer electrolyte membrane 114 is Strongly adheres. As a result, it is possible to prevent the transfer of hydrogen ions from being hindered due to the separation of the interface, thereby suppressing the deterioration of the battery performance. In addition, the physical strength of the battery is increased and the durability is improved.

Next, a preferred embodiment of the first and second solid polymer electrolytes in the present invention will be described.

From the viewpoint of effectively suppressing crossover, it is effective to select the first and second solid polymer electrolytes as follows.

(i) As the second solid polymer electrolyte, a material having a lower methanol permeability than the first solid polymer electrolyte is selected. '

(ii) As the second solid polymer electrolyte, a material having a lower moisture content than the first solid polymer electrolyte is selected.

(iiii) As the second solid polymer electrolyte, a material having a lower polar group-containing density than the first solid polymer electrolyte is selected.

(iv) As the second solid polymer electrolyte, a material having a lower fluorine content than the first solid polymer electrolyte is selected.

By adopting such a method, it is possible to suppress the permeation of the organic liquid fuel in the solid polymer electrolyte membrane 114, and to suppress a decrease in the battery performance due to the crossover. Hereinafter, methods for measuring the physical properties shown in the above G) to (iv) will be described.

Methanol permeability can be measured as follows. Inject 50 cc of 99.5% methanol on one side and 50 cc of pure water on the other side into a liquid container separated by the electrolyte membrane to be measured (film thickness 50 ΐη, area 1 cm ² ). Seal the liquid so that it does not evaporate. In pure water The time change of the concentration of methanol permeating the electrolyte membrane to be measured is measured by gas chromatography to determine the amount of methanol permeated. When the configuration (i) is adopted, the second solid polymer electrolyte has a membrane area of 50 μιη and a permeation amount of methanol per unit time of 300 mo 1 / cm ² / h or less is preferable. By selecting such a material, it is possible to prevent the methanol from reaching the oxidizing agent, and it is possible to overcome the crossover problem.

The water content is expressed as (B-A) ZA, where A is the weight of the test material dried at 100 for 2 hours and B is the weight of the test material after immersion in pure water for 24 hours. Value.

The content density of the polar group can be measured using a predetermined method according to the type of the functional group. In the case of a sulfone group, for example, it can be quantified by ion chromatography or titration after converting the sulfone group into sulfate ion by an oxygen combustion flask method or the like. The titration is performed using carboxy arsenazo as an indicator, and titration is performed with 0.01 M barium perchlorate, and the purple discoloration point is determined from the body.

The fluorine content can be quantified by X-ray fluorescence analysis or the like.

(Second embodiment)

This embodiment is different from the first embodiment in that the adhesive layer 161 also contains a catalyst and carbon particles supporting the catalyst.

The method for producing the electrode-electrolyte conjugate in the present embodiment is not particularly limited. For example, it can be produced as follows.

The catalyst layer 106 or the catalyst layer 112 can be manufactured in the same manner as in the first embodiment. The adhesive layer 161 is formed by dispersing a carbon particle supporting the second solid polymer electrolyte and the catalyst in a solvent, and forming a paste-like coating solution on the catalyst layer 106 or the catalyst layer 112, and It can be formed by coating and drying on the surface of the solid polymer electrolyte membrane 114. The carbon particles and the solid polymer electrolyte particles in the coating liquid are, for example, in a weight ratio of 1: 5 to 40: 1. Used in range. Thereby, an adhesive layer 161 containing carbon particles carrying a catalyst can be produced. In the adhesive layer 161, the content of the carbon particles supporting the catalyst is determined in the direction from the surface in contact with the catalyst layer 106 or the catalyst layer 112 to the surface in contact with the solid polymer electrolyte membrane 114. Along with a distribution. For example, the surface of the adhesive layer 161, which contacts the catalyst layer 106 or the catalyst layer 112, contains carbon particles, and the surface of the adhesive layer 161, which contacts the polymer electrolyte membrane 114, does not contain carbon particles. Can be configured.

In the present embodiment, since carbon particles carrying a catalyst are also contained in the adhesive layer 161, the electron conductivity can be improved also in the adhesive layer. (Third embodiment)

This embodiment is different from the first and second embodiments in that the adhesive layer 161 includes the first solid polymer electrolyte in addition to the second solid polymer electrolyte. By doing so, the adhesion between the adhesive layer 161 and the catalyst layer 106 or the catalyst layer 112 is more remarkably improved. In this case, the weight ratio of the second solid polymer electrolyte to the first solid polymer electrolyte in the adhesive layer 16 1 is preferably 10 to 1 to 10, more preferably 4 / :! ~ 1 Z4. Also, in the present embodiment, similarly to the second embodiment, the adhesive layer 161 may include carbon particles supporting a catalyst.

In the adhesive layer 161, the first and second solid polymer electrolytes may be distributed uniformly or non-uniformly. When the first and second solid polymer electrolytes are unevenly distributed, the content of the first solid polymer electrolyte on the surface of the adhesive layer 161 in contact with the catalyst layer 106 or the catalyst layer 112 However, it can be configured to be higher than the content of the second solid polymer electrolyte on the surface of the adhesive layer 161 in contact with the solid polymer electrolyte membrane 114. In the present embodiment, the adhesive layer 16 1 and the catalyst layer 106 contain the first solid polymer electrolyte, and the solid polymer electrolyte membrane 114 contains the second solid polymer electrolyte. In this way, the adhesion between the adhesive layer 161 and the catalyst layer 106 or the catalyst layer 112 can be improved. In addition, the adhesion between the adhesive layer 161 and the solid polymer electrolyte membrane 114 can be improved. Also in the present embodiment, the adhesive layer 161 can be formed by cross-linking by irradiating radiation in the molten state of a polymer into which a crosslinkable substituent has been introduced.

FIG. 4 is a cross-sectional view illustrating an example of the adhesive layer 161 in the present embodiment in detail. Here, the adhesive layer 16 1 can be composed of a plurality of adhesive layers 16 1 a, 16 1 b, 16 1 c, 16 1 d, and 16 e. The adhesive layer 16 1 a is a layer in contact with the catalyst layer 106 or the catalyst layer 112, and the adhesive layer 16 1 e is a layer in contact with the solid polymer electrolyte membrane 114. In such a configuration, each of the adhesive layers 161a to 161e includes both or at least one of the first solid polymer electrolyte and the second solid polymer electrolyte. In the adhesive layers 16 1 a to l 61 e, the content ratio of the second solid polymer electrolyte to the first solid polymer electrolyte is determined as follows: adhesive layer 16 1 e, adhesive layer 16 1 d, adhesive layer 1 The structure is such that the height is increased in the order of 6 1 c, the adhesive layer 16 1 b, and the adhesive layer 16 1 a. The adhesive layer 161a may be configured not to include the second solid polymer electrolyte. Further, the adhesive layer 161 e may be configured not to include the first solid polymer electrolyte. The method for producing the electrode-electrolyte conjugate in the present embodiment is not particularly limited. For example, it can be produced as follows.

The catalyst layer 106 or the catalyst layer 112 can be manufactured in the same manner as in the first embodiment. When the first and second solid polymer electrolytes are uniformly distributed in the adhesive layer 161, the first and second solid polymer electrolytes are dispersed in a solvent, and the paste-like coating liquid is applied to the catalyst layer 1. The adhesive layer 16 1 can be formed by coating and drying on 06 or the catalyst layer 112 and on the surface of Z or the solid polymer electrolyte membrane 114. The coating liquid may include carbon particles carrying a catalyst.

As described with reference to FIG. 4, when the content of the first solid polymer electrolyte in the second solid polymer electrolyte is changed in the adhesive layer 161, the adhesive layer 16 It can be made in this way. Hereinafter, description will be made with reference to FIG.

When applying the coating solution on the solid polymer electrolyte membrane 114, at least the second solid polymer electrolyte A coating solution e containing degraded particles is applied to the solid polymer electrolyte membrane 114 and dried to form an adhesive layer 161 e. Subsequently, the first and second solid polymer electrolytes are dispersed in a solvent such that the content of the first solid polymer electrolyte is higher than that of the coating solution e, and the paste-like coating solution d is bonded. Apply and dry on layer 16 1 e to form adhesive layer 16 1 d. By repeating the process of applying and drying a coating solution in which the content of the first solid polymer electrolyte is gradually increased, the first solid polymer is more distant from the solid polymer electrolyte membrane 114. An adhesive layer 161 configured to increase the content of the electrolyte can be formed. An electrode-electrolyte assembly is obtained by sandwiching the solid polymer electrolyte membrane 114 including the adhesive layer 161 formed in this manner between the fuel electrode 102 and the oxidant electrode 108 and hot pressing. be able to.

When applying the coating solution on the catalyst layer 106 or the catalyst layer 112, apply the coating solution a containing at least the first solid polymer electrolyte particles on the catalyst layer 106 or the catalyst layer 112. Application. Dry to form an adhesive layer 16a. Next, the first and second solid polymer electrolytes are dispersed in a solvent such that the content of the second solid polymer electrolyte is higher than that of the coating solution a, and the paste-like coating solution is formed. b is applied onto the adhesive layer 16 1 a and dried to form an adhesive layer 16 1 b. By repeating the process of applying and drying the coating liquid in which the content of the second solid polymer electrolyte is gradually increased, the second solid polymer electrolyte becomes more distant from the catalyst layer 106 or the catalyst layer 112. It is possible to form the adhesive layer 161 configured to increase the content of the polymer electrolyte. An electrode-electrolyte assembly is obtained by sandwiching the solid polymer electrolyte membrane 114 between the fuel electrode 102 and the oxidant electrode 108 containing the adhesive layer 161 thus formed, and hot pressing. Can be

After forming the adhesive layer 16 1 on the solid polymer electrolyte membrane 114 and the catalyst layer 106 or the catalyst layer 112 as described above, respectively, the fuel electrode 102 and the oxidation An electrode-electrolyte assembly can also be obtained by sandwiching the solid polymer electrolyte membrane 114 between the agent electrodes 108 and hot pressing.

The coating liquid is applied to the solid polymer electrolyte membrane 114 and the catalyst layer 106 or the catalyst. 04819

It is also possible to use both or any one of the 23 layers 112. However, when the coating solution contains the first and second solid polymer electrolytes, it is preferable to coat the solid polymer electrolyte membrane 114. A substrate such as a carbon paper has an uneven surface, whereas the solid polymer electrolyte membrane 114 has a relatively flat surface, and the coating liquid is applied to such a flat surface. This is because applying the adhesive improves the adhesive performance.

[Example〗

Hereinafter, the electrode for a polymer electrolyte fuel cell of the present invention and a fuel cell using the same will be specifically described with reference to Examples, but the present invention is not limited thereto.

(Example 1)

In this example, naphion was used as the first solid polymer electrolyte, and sulfonated poly (4-phenoxybenzoyl-1,1,4-phenylene) (hereinafter, referred to as “the second solid polymer electrolyte”). PPBP). The first solid polymer electrolyte forms a part of the catalyst layer on the electrode surface, and the second solid polymer electrolyte forms a part of the catalyst layer on the electrode surface and the solid polymer electrolyte membrane. In this example, platinum was used as a noble metal catalyst for both the fuel electrode and the oxidizer electrode. A method for manufacturing a fuel cell according to this example will be described with reference to FIG.

First, 100 g of acetylene black and 100 g of acetylene black (registered trademark) were added to 500 g of dinitrodiamine platinum nitrate solution containing 3% of platinum serving as a catalyst at the fuel electrode 102 and the oxidizer electrode 108. Was mixed and stirred, and then 98 ml of ethanol (60 ml) was added as a reducing agent. This solution was stirred and mixed at about 95 ° C. for 8 hours to support the catalyst on the acetylene black particles. Then, this solution was filtered and dried to obtain catalyst-carrying carbon particles. The supported amount of platinum was about 50% based on the weight of acetylene black.

By mixing 20 mg of the above-described catalyst-carrying carbon particles and 3.5 ml of a 5% naphion solution (alcohol solution, Aldrich Co., Ltd.), naphth ions were adsorbed on the surfaces of these catalysts and carbon particles. Was. The dispersion thus obtained is subjected to ultrasonic dispersion at 50 ° C for 3 hours. 04819

The mixture was dispersed in 24 to give a paste, and paste A was obtained. This paste A was applied to a base made of carbon paper (manufactured by Toray Industries, Inc .: TGP-H-120) by screen printing, and then heated and dried at 100 ° C. to obtain a fuel electrode 102 and an oxidizer electrode 108. . The amount of platinum on the surface of the obtained electrode was 0.1 to 0.4 mg / cm ² .

Next, 10 g of finely powdered poly (4-phenoxybenzoyl-1,4-phenylene)

The mixture was suspended in 100 ml of 95% sulfuric acid and stirred for 200 hours to perform a sulfonation treatment. The PP BP thus obtained was washed with sufficient distilled water, dried and powdered, and dissolved in a dimethylformamide solution. This is referred to as solution A.

This solution A was cast on a Teflon (registered trademark) sheet and dried to obtain a solid polymer electrolyte membrane 114 having a size of 10 cm × 10 cm and a thickness of 30.

On the other hand, the solution A was applied to the surfaces of the fuel electrode 102 and the oxidizer electrode 108. The coating method was a brush coating method. After the application, the coating was dried to form an adhesive layer 161 on the surface of each electrode.

A solid polymer electrolyte membrane 114 was sandwiched between these electrodes, and hot-pressed at a temperature of 150 ° C., a pressure of 10 kgf / cm ² and a condition of 10 seconds to produce an electrode-electrolyte assembly. Further, this electrode-electrolyte assembly was set in a single cell measuring device of a fuel cell to produce a single cell.

The current-voltage characteristics of the single cell were measured using a 10 wt% aqueous methanol solution and oxygen (1.1 atm, 25 ° C) as fuel. As a result, an open circuit voltage of 0.54 V and a short circuit current of 0.18 A / cm ² were continuously observed.

The above-mentioned electrode showed good bondability to the above-mentioned solid polymer electrolyte membrane, and it was confirmed that the above-mentioned electrode effectively functions as a direct methanol fuel cell using methanol as a fuel.

FIG. 3 is a diagram schematically showing the fuel electrode 102 and the solid polymer electrolyte membrane 114 of the fuel cell of the present embodiment, and the adhesive layer 161 interposed therebetween. As shown in the drawing, the catalyst layer of the fuel electrode 102 of the present embodiment includes a first solid polymer electrolyte 150 made of naphth ions and carbon particles 140 carrying a catalyst (not shown). Adhesive layer 161 is a second The main component is a solid polymer electrolyte 160. The solid polymer electrolyte membrane 114 is made of PP BP. Since the adhesive layer 161 and the solid polymer electrolyte membrane 114 both contain PPBP, the adhesion between them is good. On the other hand, the adhesion between the adhesive layer 161 and the fuel electrode 102 is also good because naphion and PP BP particles are entangled and bonded. From the above, the adhesive layer 161 functions as a binder between the solid polymer electrolyte membrane 114 and the fuel electrode 102, and the bondability between the solid polymer electrolyte membrane 114 and the fuel electrode 102 is improved. As a result, It is considered that this contributes to good operation of the fuel cell in this embodiment. Table 1 shows the values of the methanol permeability and water content of PPBP and naphion.

(table 1)

In the present embodiment, as the solid polymer electrolyte membrane 114 and the second solid polymer electrolyte 160, a material having a lower methanol permeability and a lower moisture content than the first solid polymer electrolyte 150 is selected. Thus, permeation of methanol in the solid polymer electrolyte membrane 114 is suppressed. This suggests that a decrease in cell performance due to crossover was suppressed, and that a fuel cell with good cell characteristics was obtained.

(Example 2)

Also in this example, naphion was used as the first solid polymer electrolyte, and PPBP was used as the second solid polymer electrolyte. Also in this example, platinum was used for the fuel electrode and the oxidant electrode as the catalyst. ,

The fuel electrode 102, the oxidizer electrode 108, and the solid polymer electrolyte membrane 114 were produced in the same manner as in Example 1. PPBP and catalyst-supporting carbon particles obtained in the same manner as in Example 1 were The residue was dissolved in a amide solution to obtain a first B. The paste B was applied to the surfaces of the fuel electrode 102 and the oxidizer electrode 108 by a brush coating method, and dried after application, to form an adhesive layer 161 on the surface of each electrode.

A solid polymer electrolyte membrane 114 was sandwiched between these electrodes, and hot-pressed at a temperature of 150 ° C., a pressure of 10 kg f / cm ² , and for 10 seconds, to produce an electrode-electrolyte assembly. Further, this electrode-electrolyte assembly was set in a single cell measuring device of a fuel cell to produce a single cell.

The current-voltage characteristics of the single cell were measured using 10 wt% methanol aqueous solution and oxygen (1.1 atm, 25 ° C) as fuel. As a result, an open-circuit voltage of 0.54 V and a short-circuit current of 0.19 A / cm ² were continuously observed.

FIG. 5 is a diagram schematically showing the fuel electrode 102 and the solid polymer electrolyte membrane 114 of the fuel cell of this embodiment, and the adhesive layer 161 interposed therebetween. As shown, the adhesive layer 161 includes P P BP and carbon particles 140. Since both the adhesive layer 161 and the solid polymer electrolyte membrane 114 contain PPBP, the adhesion between them is good. On the other hand, since the particles of the naphth ion and the PPBP are entangled with each other, the adhesion between the adhesive layer 161 and the fuel electrode 102 is also good. Here, since the conductive carbon particles 140 are also included in the adhesive layer 161, the electron conductivity of the adhesive layer can be improved. From the above, the bonding property between the solid polymer electrolyte membrane 114 and the fuel electrode 102 is improved due to the presence of the bonding layer 161, and the organic liquid fuel can be consumed also in the bonding layer. It is considered that the electron conductivity can be improved, which contributes to the favorable operation of the fuel cell in this embodiment.

(Example 3),

Also in this example, naphion was used as the first solid polymer electrolyte, and PP BP was used as the second solid polymer electrolyte. Also in this embodiment, as the catalyst, both the fuel electrode and the oxidizer electrode are used. PC picture 19

Platinum was used for 27.

The fuel electrode 102, the oxidizer electrode 108, and the solid polymer electrolyte membrane 114 were produced in the same manner as in Example 1. The solution A of PPPBP obtained in the same manner as in Example 1 was mixed with the naphion paste A obtained in the same manner as in Example 1 to obtain a paste C and a paste D. At this time, the naphion and the PPBP in the paste C are in a weight ratio of 1: 1. Naphion in PP D and PPBP are 4: 1 by weight.

First, paste C was applied to both sides of the solid polymer electrolyte membrane 114 by a brush coating method, and dried after application. Next, paste D was applied onto paste C by a brush coating method, and dried after application. As a result, an adhesive layer 161 composed of the paste C and the paste D was formed on both surfaces of the solid polymer electrolyte membrane 114. Using this, hot pressing was performed in the same manner as in Example 1 to produce an electrode-electrolyte assembly. This electrode-electrolyte assembly was set in a unit for measuring a single cell of a fuel cell to produce a single cell.

The current-voltage characteristics of the single cell were measured using a 1 Owt% methanol aqueous solution and oxygen (1.1 atm, 25 ° C) as fuel. As a result, an open circuit voltage of 0.54 V and a short circuit current of 0.19 A / cm ² were continuously observed.

FIG. 6 is a diagram schematically showing the fuel electrode 102 and the solid polymer electrolyte membrane 114 of the fuel cell of the present embodiment, and the adhesive layer 161 interposed therebetween. As shown in the figure, the adhesive layer 161 has a high content of the second solid polymer electrolyte 160 (PPBP) in a region near the solid polymer electrolyte membrane 114 and a first solid polymer polymer in a region near the catalyst layer 106. It is configured to increase the content of electrolyte 150 (Nafion). In the region of the adhesive layer 161 near the solid polymer electrolyte membrane 114, the PPBP content is high, so that the adhesion between the two is good. On the other hand, in a region of the adhesive layer 161 close to the catalyst layer 106, the content of naphtho ions is high, so that the adhesion between the adhesive layer 161 and the fuel electrode 102 is also good. From the above, it is considered that the presence of the adhesive layer 161 improves the bondability between the solid polymer electrolyte membrane 114 and the fuel electrode 102, and contributes to the good operation of the fuel cell in this embodiment. (Example 4)

Also in this example, naphion was used as the first solid polymer electrolyte, and PPBP was used as the second solid polymer electrolyte. Also in this example, platinum was used for the fuel electrode and the oxidant electrode as the catalyst.

The fuel electrode 102, the oxidizer electrode 108, and the solid polymer electrolyte membrane 114 were produced in the same manner as in Example 1. To the same paste C and paste D as in Example 3, 2 OOmg of the catalyst-supporting carbon particles were added, respectively, to obtain paste E and paste F.

First, paste E was applied to both sides of solid polymer electrolyte membrane 114 by a brush coating method, and dried after application. Next, paste F was applied on paste E by a brush coating method, and dried after application. Thus, an adhesive layer 161 composed of the paste E and the paste F was formed on both surfaces of the solid polymer electrolyte membrane 114. Using this, hot pressing was performed in the same manner as in Example 1 to produce an electrode-electrolyte assembly. This electrode-electrolyte assembly was set in a unit for measuring a single cell of a fuel cell to produce a single cell.

The current-voltage characteristics of the single cell were measured using 1 Owt% methanol aqueous solution and oxygen (1.1 atm, 25 ° C) as fuel. As a result, open circuit voltage 0.54V, short circuit current 0.2

OA / cm ² was continuously observed.

FIG. 7 is a diagram schematically showing the fuel electrode 102 and the solid polymer electrolyte membrane 114 of the fuel cell of the present embodiment, and the adhesive layer 161 interposed therebetween. As shown in the figure, the adhesive layer 161 has a high content of the second solid polymer electrolyte 160 (PPBP) in a region near the solid polymer electrolyte membrane 114 and a first solid polymer polymer in a region near the catalyst layer 106. It is configured to increase the content of electrolyte 150 (Nafion). Adhesive layer 161 also contains carbon particles 140. In the present embodiment, as in the third embodiment, the bonding property between the solid polymer electrolyte membrane 114 and the fuel electrode 102 is improved by the presence of the adhesive layer 161. In addition, since the adhesive layer 161 also contains conductive carbon particles 140, the electron conductivity of the adhesive layer can be improved. Accordingly, it is considered that the fuel cell in the present example shows good operation. (Comparative Example 1)

In this comparative example, the first solid polymer electrolyte constituting the fuel electrode 102 and the oxidant electrode 108, and the second solid polymer electrolyte constituting the solid polymer electrolyte membrane 114, In each case, Nafion was used, and no adhesive layer 16 1 was provided. Here, the first solid polymer electrolyte forms a part of the catalyst layer on the electrode surface, and the second solid polymer electrolyte forms a solid polymer electrolyte membrane. The solid polymer electrolyte membrane 114 was produced in the same manner as in the above example, except that PPBP was changed to naphion.

The fuel electrode 102 and the oxidant electrode 108 were produced in the same manner as in Example 1.

Subsequently, the solid polymer electrolyte membrane 114 is sandwiched between the fuel electrode 102 and the oxidizer electrode 108, and hot-pressed at a temperature of 150, a pressure of 10 kgf / cm ² , and 10 seconds. As a result, an electrode-electrolyte assembly was produced.

Further, these were set in an apparatus for measuring a single cell of a fuel cell to produce a single cell.

The current-voltage characteristics of the single cell were measured using a 10 wt% methanol aqueous solution and oxygen (1.1 atm, 25 ° C) as fuel. As a result, an open-circuit voltage of 0.45 V and a short-circuit current of 0.09 A / cm ² were observed.

In this comparative example, it is inferred that the battery efficiency was lowered due to crossover of methanol from the fuel electrode to the oxidant electrode.

(Comparative Example 2)

In this comparative example, PBPBP was used as the first solid polymer electrolyte and the second solid polymer electrolyte, and no adhesive layer 161 was provided. Here, the first solid polymer electrolyte forms a part of the catalyst layer on the electrode surface, and the second solid polymer electrolyte forms a solid polymer electrolyte membrane. The solid polymer electrolyte membrane 114 was produced using PBP in the same manner as in the above example.

The fuel electrode 102 and the oxidizer electrode 108 were prepared as follows. First, the embodiment The catalyst-supporting carbon particles obtained in the same manner as in Example 1 were added to Solution A (containing PPBP) of Example 1 to obtain a dispersion. The dispersion thus obtained was dispersed in an ultrasonic disperser at 50 ° C. for 3 hours to obtain a paste, and paste B was obtained. This paste B is applied by screen printing to the bases 104 and 110 made of carbon paper (manufactured by Toray: TGP-H-120), and then heated and dried at 100 to dry the fuel electrode 102 and the oxidizer electrode. 108 was obtained. The amount of platinum on the obtained electrode surface was 0.1 to 0.4 mg / cm ² .

Subsequently, the solid polymer electrolyte membrane 114 was sandwiched between the fuel electrode 102 and the oxidizer electrode 108, and hot-pressed at a temperature of 150 ° C., a pressure of 10 kg fZcm ² and a duration of 10 seconds to produce an electrode-electrolyte assembly. .

Further, these were set in an apparatus for measuring a single cell of a fuel cell to produce a single cell. A discharge test similar to that of the above example was performed, but no stable discharge could be confirmed.

This comparative example has a configuration in which the first solid polymer electrolyte 150 (naphion) in FIG. 3 is replaced by the second solid polymer electrolyte 160 (PPBP). As shown in Table 1, the second solid polymer electrolyte 160 (PPBP) is inferior in methanol permeability and water content to the first solid polymer electrolyte 150 (Naphion). Therefore, it is presumed that the movement of hydrogen ions from the fuel electrode to the oxidizer electrode was insufficient, and the battery did not function stably.

(Comparative Example 3)

In this comparative example, a configuration was adopted in which naphthion was used as the first solid polymer electrolyte, PPBP was used as the second solid polymer electrolyte, and the adhesive layer 161 was not provided. Here, the first solid polymer electrolyte constituted part of a catalyst layer on the electrode surface, and the second solid polymer electrolyte constituted a solid polymer electrolyte membrane.

After preparing the fuel electrode 102, the oxidant electrode 108, and the solid polymer electrolyte membrane 114 by the same method as in Example 1, the fuel electrode 102, the oxidant electrode 108, and the solid polymer electrolyte membrane 114 Although the two were thermocompression bonded, the two were not sufficiently joined, and a fuel cell that could withstand the evaluation could not be obtained.

In the above examples, when a platinum-ruthenium catalyst was used as the noble metal catalyst of the oxidant electrode 108, it was shown that each of the examples had more stable battery characteristics. The above embodiments and examples are described by way of example, and the present invention should not be limited to the above embodiments, and various modifications and variations may be made by those skilled in the art without departing from the scope of the present invention. Done.

Claims

The scope of the claims

1. a catalyst electrode including a first solid polymer electrolyte and a catalyst substance; a solid polymer electrolyte membrane; a second polymer electrolyte provided between the catalyst electrode and the solid polymer electrolyte membrane; A fuel cell, comprising: an adhesive layer;

2. The fuel cell according to claim 1, wherein the adhesive layer and the solid polymer electrolyte membrane are in contact with each other.

3. The fuel cell according to claim 1, wherein the adhesive layer and the catalyst electrode are in contact with each other.

4. The fuel cell according to claim 1, wherein the second solid polymer electrolyte has higher adhesion to the solid polymer electrolyte membrane than the first solid polymer electrolyte. .

5. The fuel cell according to claim 1, wherein the second solid polymer electrolyte comprises a solid polymer electrolyte constituting the solid polymer electrolyte membrane or a derivative thereof.

6. The fuel cell according to claim 1, wherein an organic liquid fuel is supplied to the catalyst electrode.

7. The fuel cell according to claim 6, wherein the organic liquid fuel is methanol.

8. The fuel cell according to claim 1, wherein the second solid polymer electrolyte has a lower permeability of the organic liquid fuel than the first solid polymer electrolyte. .

9. The fuel cell according to claim 1, wherein the second solid polymer electrolyte has a lower moisture content than the first solid polymer electrolyte.

10. The fuel cell according to claim 1, wherein each of the first solid polymer electrolyte and the second solid polymer electrolyte includes a proton acid group.

11. The fuel cell according to claim 1, wherein the first solid polymer electrolyte is made of a polymer containing fluorine.

12. The fuel cell according to claim 1, wherein the second solid polymer electrolyte is made of a polymer containing no fluorine.

13. The fuel cell according to claim 1, wherein the second solid polymer electrolyte is made of an aromatic-containing polymer.

14. The fuel cell according to claim 1, wherein the adhesive layer is composed mainly of the second polymer electrolyte.

15. The fuel cell according to claim 1, wherein the adhesive layer further includes the first polymer electrolyte.

16. The fuel cell according to claim 1, wherein the adhesive layer includes the catalyst electrode and the solid electrode. The second solid polymer electrolyte in a surface of the adhesive layer in contact with the catalyst electrode, wherein the content of the second solid polymer electrolyte in the surface of the adhesive layer in contact with the catalyst electrode is the same as that in the surface of the adhesive layer in contact with the solid polymer electrolyte membrane. A fuel cell, wherein the content is lower than the content of the second solid polymer.

17. The fuel cell according to claim 1, wherein the adhesive layer contains a catalytic substance.

18. The fuel cell according to claim 17, wherein the adhesive layer is provided in contact with the catalyst electrode and the solid polymer electrolyte membrane, and the catalyst substance on a surface of the adhesive layer in contact with the catalyst electrode. Wherein the content of the catalyst layer is higher than the content of the catalyst substance on the surface of the adhesive layer in contact with the solid polymer electrolyte membrane.

19. The fuel cell according to claim 1, wherein the catalyst material includes a catalyst metal and conductive particles carrying the catalyst metal.

20. A fuel cell comprising: an electrode layer containing a catalyst substance and a first solid polymer electrolyte; and an adhesive layer containing a second solid polymer electrolyte formed on the electrode layer. electrode.

21. The fuel cell electrode according to claim 20, wherein the second solid polymer electrolyte has a lower methanol permeability than the first solid polymer electrolyte.

22. The electrode for a fuel cell according to claim 20, wherein the second solid polymer electrolyte has a lower moisture content than the first solid polymer electrolyte.

23. The fuel cell electrode according to claim 20, wherein the first solid polymer electrolyte and the second solid polymer electrolyte both contain a protonic acid group. Electrodes for fuel cells.

24. The fuel cell electrode according to claim 20, wherein the first solid polymer electrolyte is made of a polymer containing fluorine.

25. The fuel cell electrode according to claim 20, wherein the second solid polymer electrolyte is made of a polymer containing no fluorine.

26. The fuel cell electrode according to claim 20, wherein the second solid polymer electrolyte is made of an aromatic-containing polymer.

27. The fuel cell electrode according to claim 20, wherein the contact layer includes the first solid polymer electrolyte.

28. The fuel cell electrode according to claim 20, wherein the adhesive layer is provided in contact with the catalyst layer, and the second solid polymer electrolyte is provided on a surface of the adhesive layer in contact with the catalyst layer. An electrode for a fuel cell, wherein the content is lower than the content of the second solid polymer electrolyte on a surface opposite to a surface in contact with the catalyst layer.

29. The fuel cell electrode according to claim 20, wherein the adhesive layer contains a catalytic substance.

30. The fuel cell electrode according to claim 29, wherein the adhesive layer is in contact with the catalyst layer. Wherein the content of the catalyst substance on the surface of the adhesive layer that is in contact with the catalyst layer is higher than the content of the catalyst substance on the surface opposite to the surface that is in contact with the catalyst layer. Electrodes for fuel cells.

31. The fuel cell electrode according to claim 20, wherein the catalyst substance comprises a catalyst metal and conductive particles carrying the catalyst metal.

32. A method for producing a fuel cell electrode in which a catalyst layer and an adhesive layer are formed in this order on a substrate, comprising: a conductive particle carrying a catalyst metal; and a particle containing a first solid polymer electrolyte. Applying the first coating solution to the substrate to form the catalyst layer; and forming particles containing a second solid polymer electrolyte made of a polymer different from the first solid polymer electrolyte. Coating the second coating solution contained on the catalyst layer to form the adhesive layer. A method for producing an electrode for a fuel cell, comprising:

33. The method for producing an electrode for a fuel cell according to claim 32, wherein the second solid polymer electrolyte has a lower methanol permeability than the first solid polymer electrolyte. A method for manufacturing a battery electrode.

34. The method for manufacturing a fuel cell electrode according to claim 32, wherein the second solid polymer electrolyte has a lower moisture content than the first solid polymer electrolyte. For manufacturing electrodes.

35. A method for manufacturing an electrode for a fuel cell according to claim 32! A method for producing an electrode for a fuel cell, wherein each of the first solid polymer electrolyte and the second solid polymer electrolyte contains a protonic acid group;

36. The method for manufacturing an electrode for a fuel cell according to claim 32, wherein the first solid polymer electrolyte is made of a polymer containing fluorine.

37. The method for producing a fuel cell electrode according to claim 32, wherein the second solid polymer electrolyte is made of a polymer containing no fluorine.

38. The method for manufacturing a fuel cell electrode according to claim 32, wherein the second solid polymer electrolyte is made of a polymer containing an aromatic compound. .

39. The method for producing an electrode for a fuel cell according to claim 32, wherein the second coating solution comprises a particle containing the first solid polymer electrolyte. Production method.

40. The method of manufacturing a fuel cell electrode according to claim 39, wherein the step of forming the adhesive layer comprises applying a plurality of coating liquids having different content rates of the particles including the first solid polymer electrolyte. A method for producing an electrode for a fuel cell, comprising:

41. The method for manufacturing a fuel cell electrode according to claim 32, wherein the second coating solution includes conductive particles carrying a catalyst metal.

42. The method for manufacturing an electrode for a fuel cell according to claim 41, wherein the step of forming the adhesive layer includes a step of applying a plurality of coating liquids having different contents of the conductive particles supporting the catalyst metal. A method for producing an electrode for a fuel cell, comprising:

43. After obtaining a fuel cell electrode by the method for producing a fuel cell electrode according to claim 32, A method for producing a fuel cell, comprising a step of thermocompression bonding the fuel cell electrode and the solid polymer electrolyte membrane in a state where the adhesive layer and the solid polymer electrolyte membrane are in contact with each other.

44. A method for producing a fuel cell, comprising: a solid polymer electrolyte membrane; and a pair of electrodes having the catalyst layer formed on a substrate by sandwiching the solid polymer electrolyte membrane. A step of applying a first coating solution containing particles containing one solid polymer electrolyte on a substrate to form the catalyst layer, and comprising a polymer different from the first solid polymer electrolyte. Applying a second coating solution containing particles containing a second solid polymer electrolyte to the solid polymer electrolyte membrane to form an adhesive layer; and contacting the catalyst layer with the adhesive layer. And a step of thermocompression bonding the electrode and the solid polymer electrolyte membrane in a folded state.

45. The method for manufacturing a fuel cell according to claim 44, wherein the second coating liquid contains particles containing the first solid polymer electrolyte.

46. The method for manufacturing a fuel cell according to claim 45, wherein the step of forming the adhesive layer includes a step of applying a plurality of coating liquids having different content rates of particles including the first solid polymer electrolyte. A method for manufacturing a fuel cell, comprising:

47. The method for manufacturing a fuel cell according to claim 44, wherein the second coating solution contains conductive particles carrying a catalyst metal.

48. The method of manufacturing a fuel cell according to claim 47, wherein the step of forming the adhesive layer includes a step of applying a plurality of coating solutions having different contents of the conductive particles supporting the catalyst metal. And a method of manufacturing a fuel cell.