WO2007026797A1

WO2007026797A1 - Electrolytic membrane-electrode assembly

Info

Publication number: WO2007026797A1
Application number: PCT/JP2006/317173
Authority: WO
Inventors: Yasuhiro Numao; Atsushi Ohma; Motoharu Obika
Original assignee: Nissan Motor Co., Ltd.
Priority date: 2005-08-31
Filing date: 2006-08-31
Publication date: 2007-03-08
Also published as: JP2007095669A

Abstract

Disclosed is an electrolytic membrane-electrode assembly, which comprises an electrolytic membrane (2), an anode catalyst layer (4a) provided on one surface of the electrolytic membrane (2), a cathode catalyst layer (4c) provided on the other surface of the electrolytic membrane (2), a seal (3) for preventing the leakage of a gas from a side face (4b) of the anode catalyst layer (4a), a side face (4d) of the cathode catalyst layer (4c) and a side face (2b) of the electrolytic membrane (2), and gaskets (6a, 6c) provided on the both surfaces of the seal (3). In the assembly, a part of the seal (3) forms bonding regions (7a, 7c) which bind the electrolytic membrane (2) and each of the gaskets (6a, 6c) together. The binding regions (7a, 7c) are provided on the outer peripheries in a plane-wise direction of the anode catalyst layer (4a) and the cathode catalyst layer (4c), respectively, so as to prevent the leakage of a gas from the side face (4b) of the anode catalyst layer (4a) and the side face (4d) of the cathode catalyst layer (4c). According to this configuration, the moisture permeation from the side face (2b) of the electrolyte membrane (2) can be prevented and the drying of the electrolyte membrane (2) can also be prevented effectively.

Description

Specification

Electrolyte membrane-one electrode assembly

Technical field

The present invention relates to an electrolyte membrane-electrode assembly (hereinafter also simply referred to as “MEA”) and a fuel cell using the electrolyte membrane-electrode assembly. In particular, the present invention relates to an electrolyte membrane / electrode assembly in which water vapor permeation from the electrolyte membrane is effectively prevented, and a fuel cell using the electrolyte membrane / electrode assembly.

Background art

[0002] In recent years, in response to social demands and trends against the background of energy and environmental problems, fuel cells that can operate at room temperature and obtain high output density have attracted attention as power sources for electric vehicles and stationary power sources. . A fuel cell is a clean power generation system in which the product of the electrode reaction is water in principle and has almost no adverse effect on the global environment. In particular, solid polymer electrolyte fuel cells are expected to serve as power sources for electric vehicles because they operate at relatively low temperatures. The structure of a solid polymer electrolyte fuel cell generally has a structure in which an electrolyte membrane-electrode assembly is sandwiched between separators. In the electrolyte membrane-electrode assembly, a high molecular electrolyte membrane is sandwiched between a pair of electrode catalyst layers, and a polymer electrolyte membrane and an electrode catalyst layer are sandwiched between a pair of gas diffusion layers.

[0003] In the polymer electrolyte fuel cell having MEA as described above, the following electrochemical reaction proceeds. First, hydrogen contained in the fuel gas supplied to the anode side is oxidized by the catalyst component to become protons and electrons (2H → 4H ++ 4e−). Next, raw

2

The formed protons pass through the polymer electrolyte membrane in contact with the solid polymer electrolyte contained in the anode side electrode catalyst layer and the anode side electrode catalyst layer, and reach the force sword side electrode catalyst layer. . In addition, the electrons generated in the anode side electrode catalyst layer are in contact with the conductive carrier constituting the anode side electrode catalyst layer !, and further on the side different from the polymer electrolyte membrane of the anode side electrode catalyst layer, Reaches the force sword side electrode catalyst layer through the gas diffusion layer, separator and external circuit. The protons and electrons that have reached the force sword side electrode catalyst layer react with oxygen contained in the oxidant gas supplied to the force sword side to generate water (O + 4H + + 4e "→ 2H 0). In a fuel cell, electricity is taken outside through the electrochemical reaction described above.

2

It becomes possible to put out.

[0004] Conventionally, various studies have been made on the structure of such an MEA. For example, in a solid polymer electrolyte fuel cell, conventionally, a fuel gas and an oxidant gas in a gas supply groove do not leak to the outside through a laminated surface of MEA, and a gap is provided around the electrode catalyst layer. A gas seal was placed. However, such a gap has a problem in that the solid polymer electrolyte membrane is damaged immediately upon receiving mechanical stress due to the differential pressure of the reaction gas applied to the solid polymer electrolyte membrane or the creep of the membrane. In order to solve this problem, it has been reported that a reinforcing film Z protective film is disposed in a gap portion between the electrode catalyst layer and the gas sealing material which are easily damaged (Japanese Patent Laid-Open No. 5-242897). No. 5, JP-A-5-21077).

[0005] In addition, in a conventional solid polymer electrolyte fuel cell, a gap is formed between the separator and the gasket, and fuel or oxidant gas leaks, resulting in a decrease in performance or adhesion between the separator and the electrode. However, the sufficient power generation characteristics may not be exhibited. Therefore, in order to solve such a problem, in the single cell in which the electrolyte membrane-electrode assembly having the gasket is sandwiched by the separator, the thickness of the gasket (gas seal) before being sandwiched by the separator is set to the electrode. A single cell having a thickness smaller than that of the above is disclosed (see JP 2002-324556 A).

Disclosure of the invention

However, in the MEA disclosed in the above document, a reinforcing film Z protective film (Japanese Patent Laid-Open No. 5-242897, Japanese Patent Laid-Open No. 5-21077) is provided on the surface around the electrolyte film to prevent gas leakage. No.) and a gas seal (Japanese Patent Laid-Open No. 2002-324556) are provided. Side surfaces of the electrolyte membrane are open, and no gas seal structure is provided. For this reason, as described above, a part of the water generated on the force sword electrode catalyst layer side is discharged to the outside through the side surface portion of the electrolyte membrane, and the presence of the generated water on the force sword electrode catalyst layer side causes the electrolyte to flow out. The membrane cannot be maintained in a moderately moist state. For this reason, in such a structure, the electrolyte membrane dries and the strength decreases, and the humidity of the external atmosphere increases, which decreases the durability and power generation performance of the MEA. There was a problem that. [0007] The present invention has been made in order to solve the above-described problems, and an object of the present invention is to provide an electrolyte membrane-electrode assembly in which drying of the electrolyte membrane is suppressed and durability is improved. Another object of the present invention is to provide an electrolyte membrane-electrode assembly having a structure in which the electrolyte membrane is an inexpensive material and is simply edge-sealed.

[0008] An electrolyte membrane electrode assembly according to an aspect of the present invention includes an electrolyte membrane, an anode catalyst layer provided on one surface of the electrolyte membrane, and a cathode provided on the other surface of the electrolyte membrane. A catalyst layer, a seal for preventing gas leakage from the side surface of the anode catalyst layer and the side surface of the force sword catalyst layer, and the side surface of the electrolyte membrane, and a gasket provided on both surfaces of the seal, A part of the seal forms an adhesion part for adhering the electrolyte membrane and the gasket, and the adhesion part is formed on the outer periphery of the anode catalyst layer and the force sword catalyst layer in the surface direction of the anode catalyst layer. Arranged to prevent gas leakage from the side and side of the force sword catalyst layer.

Brief Description of Drawings

FIG. 1A is a cross-sectional view showing an example of the arrangement of water vapor seal members in the MEA of the present invention.

FIG. 1B is a cross-sectional view showing an example of the arrangement of water vapor seal members in the MEA of the present invention.

FIG. 1C is a cross-sectional view showing an example of the arrangement of water vapor seal members in the MEA of the present invention.

FIG. 1D is a cross-sectional view showing an example of the arrangement of water vapor seal members in the MEA of the present invention.

FIG. 1E is a cross-sectional view showing an example of the arrangement of water vapor seal members in the MEA of the present invention.

FIG. 1F is a cross-sectional view showing an example of the arrangement of the water vapor seal members in the MEA of the present invention.

FIG. 2A is a cross-sectional view for explaining the positional relationship between a water vapor seal member and a sealing convex portion in the MEA of the present invention.

[FIG. 2B] FIG. 2B shows the positions of the water vapor seal member and the sealing convex portion in the MEA of the present invention. It is sectional drawing explaining arrangement | positioning relationship.

FIG. 3A is a plan view showing an example of the positional relationship of the water vapor seal member with respect to the electrolyte membrane.

FIG. 3B is a plan view showing an example of the positional relationship of the water vapor seal member with respect to the electrolyte membrane.

FIG. 3C is a plan view showing an example of a positional relationship of the water vapor seal member with respect to the electrolyte membrane.

FIG. 4 is a cross-sectional view of the MEA of the present invention when the gasket and the water vapor seal member are formed as a single body.

FIG. 5A is a cross-sectional view of the MEA of the present invention when it has a reinforcing member.

FIG. 5B is a cross-sectional view of the MEA of the present invention when it has a reinforcing member.

[FIG. 5C] FIG. 5C is a cross-sectional view of the MEA of the present invention in the case of having a reinforcing member having adhesive ability.

FIG. 5D is a cross-sectional view of the MEA of the present invention when it has a reinforcing member and a reinforcing layer.

FIG. 6A is a cross-sectional view of the MEA of the present invention in the case where the adhesive layer is formed inside the electrolyte membrane beyond the gasket.

FIG. 6B is a cross-sectional view of the MEA of the present invention when the adhesive layer is formed inside the electrolyte membrane beyond the gasket.

[FIG. 7] FIG. 7 is a diagram for explaining one step of a method for producing an MEA of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the electrolyte membrane-electrode assembly of the present invention will be described in detail with reference to the drawings.

As shown in FIG. 1A, an electrolyte membrane electrode assembly 1 of the present invention includes an electrolyte membrane 2, an anode catalyst layer 4a disposed on one surface of the electrolyte membrane 2, and the electrolyte membrane. A force sword catalyst layer 4c disposed on the other surface. Furthermore, the electrolyte membrane-electrode assembly 1 includes a gas diffusion layer 5a formed on the anode catalyst layer 4a and a gas diffusion layer 5c formed on the force sword catalyst layer 4c in the thickness direction. Prepare. [0012] In addition, the electrolyte membrane-one electrode assembly 1 of the present invention includes an anode side gasket 6a provided on the outer peripheral portion in the surface direction of the anode catalyst layer 4a and the gas diffusion layer 5a, and preventing leakage of fuel gas. A force sword side gasket 6c is provided on the outer peripheral portion in the surface direction of the force sword catalyst layer 4c and the gas diffusion layer 5c, and prevents leakage of oxidant gas. The anode side gasket 6a and the force sword side gasket 6c are bonded to the electrolyte membrane 2 through adhesive layers (adhesive portions) 7a and 7c. The electrolyte membrane-one electrode assembly 1 and the anode side and cathode side gaskets 6a, 6c are sandwiched between a pair of separators 10a, 10c. The separator 10a is provided with a fuel gas channel 10b, and fuel gas (H or the like) is supplied to the gas diffusion layer 5a and the anode catalyst layer 4a through the fuel gas channel 10b. Also separator 1

2

Oc is provided with an oxidant gas flow path 10d, and oxidant gas (air, O, etc.) is supplied to the gas diffusion layer 5c and the force node catalyst layer 4c through the oxidant gas flow path 10d. In addition,

2

In FIG. 1B and later, the separators 10a and 10c are omitted.

[0013] Here, as described above, the anode side gasket 6a and the force sword side gasket 6c are bonded to the electrolyte membrane 2 via the bonding layers (bonding portions) 7a and 7c. In this case, the adhesive layers (adhesive portions) 7a and 7c are arranged on the outer peripheral portions in the surface direction of the anode catalyst layer 4a and the force sword catalyst layer 4c. In the figure, the anode catalyst layer 4a and the adhesive layer 7a are in contact, and the force sword catalyst layer 4c and the adhesive layer 7c are also in contact. However, the anode catalyst layer 4a and the adhesive layer 7a do not need to be in contact with each other, and the force sword catalyst layer 4c and the adhesive layer 7c do not need to be in contact with each other. Further, in the figure, the thicknesses of the adhesive layers 7a and 7c are described as being equivalent to the thicknesses of the catalyst layers 4a and 4c. However, the thickness of the adhesive layers 7a and 7c need not be equal to the thickness of the catalyst layers 4a and 4c.

The electrolyte membrane 2 used in the MEA of the present invention may be a member having at least high proton conductivity. The polymer electrolytes that can be used are broadly classified into fluorine-based electrolytes that contain fluorine atoms in all or part of the polymer skeleton, and hydrocarbon-based electrolytes that do not contain fluorine atoms in the polymer skeleton.

[0014] Specific examples of the fluorine-based electrolyte include perfluorocarbon sulfonic acid polymers such as naphthion (manufactured by DuPont), Aciplex (manufactured by Asahi Kasei Co., Ltd.), and Flemion (manufactured by Asahi Glass Co., Ltd.), poly Trifluorostyrene sulfonic acid polymer, perfluoro Carbon phosphonic acid polymer, trifluorostyrene sulfonic acid polymer, ethylene tetrafluoroethylene g-styrene sulfonic acid polymer, ethylene-tetrafluoroethylene copolymer, polyvinylidene fluoride perfluorocarbon A suitable example is a sulfonic acid polymer.

[0015] Specific examples of the hydrocarbon electrolyte include polysulfone, polysulfonic acid, polyaryl ether ketone sulfonic acid, polybenzimidazole alkylsulfonic acid, polybenzimidazolenorenorequinolephosphonic acid, and polystyrene sulphonone. Suitable examples include acid, polyetherol ketone sulfonic acid, and polysulfonic sulfonic acid.

[0016] Since the polymer electrolyte is excellent in heat resistance, chemical stability, etc., fluorine-based electrolytes such as naphthions, aciplexes, and flemions are preferred among those that preferably contain fluorine atoms.

[0017] Further, as the electrolyte membrane, perfluorosulfonic acid membranes represented by various naphthion ions Flemion manufactured by DuPont, ion-exchange resin manufactured by Dow Chemical Company, ethylene tetrafluoride styrene copolymer Fluoropolymer electrolytes such as resin membranes and resin membranes based on trifluorostyrene, and solid polymer types that are generally available on the market, such as hydrocarbon-based resin membranes with sulfonic acid groups An electrolyte membrane may be used. Further, as the electrolyte membrane, a membrane in which a polymer microporous membrane is impregnated with a liquid electrolyte, or a membrane in which a porous body is filled with a polymer electrolyte may be used. In addition, as an electrolyte membrane, an electrolyte component such as phosphoric acid or ionic liquid is applied to a porous thin film such as polytetrafluoroethylene (PTFE) or polyvinylidene fluoride (PVDF). Use impregnated ones.

[0018] The thickness of the electrolyte membrane may be appropriately determined in consideration of the properties of the obtained MEA, but is preferably 5 to 300 μm, more preferably 10 to 200 μm, and particularly preferably ί. 15 ~: LOO μm. It is preferably 5 m or more from the viewpoint of strength during film formation and durability during MEA operation. From the viewpoint of output characteristics during MEA operation, it is preferably 300 μm or less.

[0019] The electrolyte membrane-electrode assembly 1 of the present invention includes a gas, particularly water vapor, from the side surface 4b of the anode catalyst layer 4a, the side surface 4d of the force sword catalyst layer 4c, and the side surface 2b of the electrolyte membrane 2. Seal 3 is provided to prevent leakage. In the electrolyte membrane-electrode assembly 1 shown in FIG. 1A, the seal 3 includes a water vapor seal member 3a and adhesive layers 7a and 7c. By providing the seal 3 in this way, leakage of gas (oxygen, hydrogen, and water vapor) from the side surface 2b of the electrolyte membrane 2 can be effectively prevented by the water vapor seal member 3a. Further, leakage of gas from the side surface 4b of the anode catalyst layer 4a and the side surface 5b of the gas diffusion layer 5a can be effectively prevented by the adhesive layer 7a and the anode side gasket 6a. Further, gas leakage from the side surface 4d of the force sword catalyst layer 4c and the side surface 5d of the gas diffusion layer 5c can be effectively prevented by the adhesive layer 7c and the force sword side gasket 6c. In addition, leakage of gas in the thickness direction of the electrolyte membrane can be prevented by the adhesive layers 7a and 7c.

[0021] At least a part of the water vapor seal member 3a is formed between the anode side and force sword side gaskets 6a, 6c provided on the outer peripheral portions of the gas diffusion layers 5a, 5c. In other words, the water vapor seal member 3a is disposed on at least a part of the lateral outer periphery of the electrolyte membrane. Here, “the lateral outer periphery of the electrolyte membrane” means the entire electrolyte membrane portion (arrow A portion in FIG. 1A) in contact with one of the adhesive layers 7a and 7c. In the present invention, when the force sword catalyst layer and the anode catalyst layer are formed at different positions, the water vapor seal member is in contact with the adhesive layer on at least one side of the anode catalyst layer and the force sword catalyst layer. However, it is preferably arranged in the electrolyte membrane part in contact with the adhesive layer on both catalyst layers.

That is, as the arrangement position of the water vapor seal member 3a in the present invention, as shown in FIG. 1A, when the water vapor seal member 3a is formed at the end (outermost peripheral portion) of the electrolyte membrane 2, or FIG. As shown in FIG. 4, there is a case where the water vapor seal member 3a is formed in the electrolyte membrane 2 at a position corresponding to the middle of the gaskets 6a and 6c. In addition, as shown in FIG. 1C, when the water vapor seal member 3a is formed between the gaskets 6a and 6c by urging inward from the end of the electrolyte membrane 2, or as shown in FIG. There may be a case where the member 3a is formed toward the inside of the electrolyte membrane 2 beyond the joint surfaces 9a and 9c of the end force gaskets 6a and 6c of the electrolyte membrane 2 and the gas diffusion layers 5a and 5c. Further, as shown in FIG. 1E, the partial force bonding surface 9a, 9c of the water vapor seal member 3a is formed toward the inner side of the electrolyte membrane 2, but there may be a case where the end of the electrolyte membrane 2 is not included. In FIG. 1D and FIG. 1E, the joining surfaces 9a and 9c of the anode-side and force-sword-side gaskets 6a and 6c and the gas diffusion layers 5a and 5c are at the same position with respect to the MEA thickness direction. An embodiment was shown. Force and these When the joint surfaces 9a and 9c are at different positions with respect to the thickness direction of the MEA, the water vapor seal member 3a is formed from at least one of the joint surfaces 9a and 9c toward the inside of the electrolyte membrane 2. Just do it. However, it is preferable that the water vapor seal member 3a is formed at least on the inner side of the electrolyte membrane 2 from the joint surface 9c between the gas diffusion layer 5c on the force sword side and the gasket 6c. This is because water is generated particularly on the power sword side. 1A to E show an example in which the electrolyte membrane 2 and the water vapor seal member 3a are in close contact with each other, but there may be a gap 11 between them as shown in FIG. 1F. . Even in such a case, the gas leak in the thickness direction of the electrolyte membrane 2 is caused by the gas impermeable gaskets 6a and 6c, and the gas leak in the surface direction of the electrolyte membrane 2 is caused by the water vapor seal member 3a. They can also prevent each. In the present specification, “inside” means the center side of the electrolyte membrane / electrode assembly in the thickness direction or the surface direction.

[0023] Among the above examples, the water vapor sealing member 3a is preferably arranged so as to include at least a part of the outermost peripheral portion of the electrolyte membrane 2. This is because such a structure can effectively prevent the permeation of water vapor from the side surface 2b of the electrolyte membrane 2 and maintain the humidity of the electrolyte membrane 2 well. In addition, such a structure makes it easier to perform the process of forming the water vapor seal member 3a as compared with the case where it is formed in the middle of the lateral outer periphery of the electrolyte membrane 2 as shown in FIG. 1B, for example. Can do. In the present specification, the “outermost peripheral portion of the electrolyte membrane” means the portion of the electrolyte membrane 2 farthest from the catalyst layers 4a and 4c, that is, as shown in FIGS. 1A, 1C and ID, The case where the sealing member is formed so as to include the end portion of the electrolyte membrane is included.

[0024] Further, it is preferable that the water vapor seal member 3a is disposed at a position corresponding to at least a portion where a reaction force is applied to the gaskets 6a and 6c. Here, “part where reaction force is applied to the gasket” refers to a part where compression pressure is applied in the thickness direction of the MEA. For example, a solid polymer electrolyte fuel cell has a structure in which an electrolyte membrane-electrode assembly 1 is sandwiched between separators 10a and 10c, and fuel gas and oxidant gas are supplied from the separators 10a and 10c. In this case, as shown in FIG. 2A, when the MEA is sandwiched between the separators 10a and 10c so that the fuel gas and the oxidant gas flow independently and do not leak to the outside, the sealing protrusion (lip) 8a , 8c are arranged on the gaskets 6a, 6c. For this reason, in the arrangement part of convex parts 8a and 8c, Compression pressure is applied when the MEA is sandwiched between the separators 10a and 10c. Here, in the thickness direction, when the electrolyte membrane 2 is located at a position corresponding to the convex portion arrangement site, the electrolyte membrane 2 is thin and low in strength. 4a and force sword catalyst layer 4c may come into contact with each other to cause a short circuit. On the other hand, as described in detail below, the water vapor seal member 3a formed of an adhesive or a material having a high compression elastic modulus is disposed in a portion where a reaction force is applied to the gaskets 6a and 6c, thereby separating the separators 10a and 10c. Even when the MEA is clamped by the electrolyte membrane, the electrolyte membrane 2 will not be crushed by the compressive stress. In such a case, the arrangement position of the water vapor seal member 3a may be at least partially formed between the convex portions 8a and 8c in the case of the solid polymer electrolyte fuel cell. However, as shown in FIG. 2A, the water vapor seal member 3a is preferably formed completely between the convex portions 8a and 8c. In addition, as shown in FIG. 2B, when the convex portions 8a and 8c are arranged so as to be shifted from each other on the anode and force sword sides, they are within the range of the water vapor seal member 3a (arrow B in FIG. 2B). It is preferable that both the convex portions 8a and 8c are completely included in the portion). In FIGS. 2A and 2B, the cross-sectional shapes of the convex portions 8a and 8c are triangular. However, this shape is not particularly limited as long as the sealability of the electrolyte membrane-electrode assembly can be improved, and the cross-sectional shape is a triangle or more polygon, quadrilateral, rectangle, cylinder, truncated cone, Polygonal columns and polygonal frustums can also be used. The portions where the convex portions 8a and 8c are formed are not particularly limited as long as the sealability of the electrolyte membrane / electrode assembly can be improved, and is formed in contact with at least a part of the gaskets 6a and 6c. That's fine. Further, the outer periphery of the catalyst layers 4a and 4c on the electrolyte membrane 2 may be scattered so that the convex portions 8a and 8c may be scattered so as to fill the concave portions of the separator such as the fuel gas flow channel 10b and the oxidant gas flow channel 10d. The convex portions 8a and 8c may be formed in a frame shape so as to surround the frame. In addition, the convex portions 8a, 8c formed on the gaskets 6a, 6c are fitted between the convex portions 8a, 8c formed on the gaskets 6a, 6c. The protrusions 8a and 8c that may be formed may have an O-ring shape. Further, the material of the convex portions 8a and 8c is not particularly limited as long as the material can ensure the sealing property between the separators 10a and 10c and the electrolyte membrane-electrode assembly 1. For example, rubber materials such as fluorine rubber, silicon rubber, ethylene propylene rubber (EPDM), polyisobutylene rubber, polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), poly Preferable examples include fluorine-based polymer materials such as xafluoropropylene and tetrafluoroethylene-hexafluoropropylene copolymer (FEP), and thermoplastic resins such as polyolefin and polyester. If these materials are used, the electrolyte membrane-electrode assembly and the separator can be brought into close contact with each other by elastic deformation, and the gas sealability is improved. The thickness of the convex portions 8a and 8c may be about 2mm to 50m, preferably about lmm to 100m.

[0026] In the present invention, the water vapor seal member 3a is disposed at least at a part of the lateral outer peripheral portion of the electrolyte membrane 2, but as high as possible in the gas (especially water vapor) sealability in the electrolyte membrane 2. Since it is preferably maintained, the water vapor sealing member 3a is preferably formed so as not to be interrupted in the middle at the lateral outer periphery of the electrolyte membrane 2. At this time, the shape of the water vapor seal member 3a is not particularly limited as long as it is formed so as not to be interrupted halfway, but as shown in FIG. 3A (corresponding to FIG. 1A) and FIG. 3B (corresponding to FIG. 1B). It may be arranged concentrically with respect to the electrolyte membrane, or it may be arranged so that the lateral outer periphery of the electrolyte membrane 2 makes an uncircular round as shown in FIG. 3C. In consideration of the formation of the member 3a, it is preferable that the member 3a is disposed concentrically with respect to the electrolyte membrane 2. 3A to 3C show the case where the electrolyte membrane 2 has a rectangular shape, the electrolyte membrane 2 according to the present invention is not limited to the above shape, and may have a shifted shape. Further, the width of the water vapor seal member 3a is not necessarily required to be constant. For example, the width of a portion where water vapor permeates easily can be increased. In consideration of the formation of the material, it is preferable that the width of the water vapor seal member 3a is constant. Further, as shown in FIGS. 1A to 1F, various sizes can be applied as the size of the water vapor seal member 3a. However, it is preferable that the thickness of the water vapor seal member 3a is equal to the thickness of the electrolyte membrane 2 to be used. It is a force that can completely prevent permeation of water vapor from the electrolyte membrane 2.

In the present invention, the water vapor seal member 3a may be formed of a misaligned material. However, in consideration of water vapor permeability and resistance to compressive stress, the adhesive or the electrolyte membrane 2 is used. It is preferable to be made of a material with a high compression modulus. As a method of forming the water vapor seal member 3a in the former case, an adhesive is impregnated in a predetermined position of the electrolyte membrane 2. And a method of arranging an adhesive member at a predetermined position of the electrolyte membrane 2 can be used. By using such a method, the water vapor seal member 3a can be easily and simply formed, and the formation position of the water vapor seal member 3a can be accurately controlled. The adhesive that can be used at this time is not particularly limited as long as it does not transmit water vapor. However, hot melt adhesives such as polyolefin, polypropylene, and thermoplastic elastomers, acrylic adhesives, polyesters, Olefin adhesives such as polyolefin can be used. Of these, hot melt adhesives are preferably used in consideration of adhesion, precise bonding position, and long-time adhesion. When using a hot melt adhesive, the melting temperature of the hot melt adhesive is the handleability (the impregnation of the electrolyte membrane, the ease of forming an adhesive member), the deterioration temperature of the electrolyte membrane 2, the fuel Considering durability at the use temperature as a battery, it is preferably 25 to 150 ° C, more preferably 70 to 120 ° C.

[0028] As a specific method for forming the water vapor seal member 3a by impregnating an adhesive at a predetermined position of the electrolyte membrane 2, a predetermined portion of the electrolyte membrane 2 is preliminarily set at 100 to 180 ° C. A method of dipping in a hot-melt adhesive that has been melted can be used. In addition, a hot melt adhesive melted in the same manner as described above can be applied to a predetermined portion of the electrolyte membrane 2 by a method such as a screen printing method, a deposition method, or a spray method.

[0029] A specific method for forming the water vapor seal member 3a by disposing an adhesive member at a predetermined position of the electrolyte membrane 2 is previously melted at 100 to 180 ° C! It is possible to use a method in which an adhesive member is formed by applying and curing a hot-melt adhesive on a transfer mount to a predetermined thickness to form an adhesive member, which is then bonded to the end of the electrolyte membrane 2.

[0030] Further, first, the gas diffusion layers 5a, 5c and the gaskets 6a, 6c are formed on the transfer mount, and further the catalyst layers 4a, 4c are formed on the gas diffusion layers 5a, 5c, and the gaskets 6a, 6c are formed. Adhesive layers 7a and 7c are formed on the substrate to form a laminate. Thereafter, the electrolyte membrane 2 can be placed at a predetermined position of the laminate, and an adhesive melted at the same temperature as described above can be applied to the remaining positions to form an adhesive member. When the adhesive layers 7a and 7c and the adhesive used for the adhesive member are the same, the gas diffusion layers 5a and 5c and the gaskets 6a and 6c are formed on the transfer mount, and further After the catalyst layers 4a and 4c are formed on the gas diffusion layers 5a and 5c, and the adhesive layers 7a and 7c and the adhesive member are simultaneously formed on the gaskets 6a and 6c, the electrolyte membrane 2 is placed on the remaining portion. Good.

[0031] As described above, the water vapor sealing member 3a has a higher compression elastic modulus than the electrolyte membrane 2.

It is preferably formed of a material (that is, not easily crushed). If such a water vapor seal member 3a is disposed at a position corresponding to the portion where the reaction force is applied to the gaskets 6a and 6c, the electrolyte membrane 2 can be used even when the MEA is sandwiched between the separators 10a and 10c and when each layer of MEA is joined. This prevents the occurrence of short circuits. As a material having a high compression elastic modulus that can be used at this time, it does not transmit water vapor, and can be resisted from the reaction force applied to the gasket when sandwiched or joined by a general separator. Any material can be used. Specific examples include hard resins such as polyethylene naphthalate (PEN), polyethylene terephthalate (PET), polytetrafluoroethylene (PTFE), and polyvinylidene fluoride (PVDF). At this time, it is preferable to use the same material as that constituting the gasket. This has the advantage that there is no need to select an adhesive, although it is economically advantageous because there is no need to prepare many types of materials. That is, as shown in FIGS. 1A to 1F, the MEA of the present invention is formed with gaskets 6a and 6c and a water vapor seal member 3a through adhesive layers 7a and 7c. In this case, if the gaskets 6a, 6c and the water vapor seal member 3a are the same, the same adhesive can provide the same adhesive strength, so the layers that make up the MEA are closely bonded with one adhesive. However, this is because a MEA with high adhesion can be obtained. When the water vapor seal member 3a is formed of the same material as that constituting the gaskets 6a and 6c, as shown in FIG. 4, any one of the gaskets 6a and 6c on the anode Z-force sword side and the water vapor seal member is used. 3a is formed integrally.

The water vapor sealing member 3a according to the present invention may be a reinforcing member 3b having higher strength than the electrolyte membrane 2. At this time, a part of the reinforcing member 3b is disposed on the outer periphery of the side of the electrolyte membrane 2 so as to be formed inside the electrolyte membrane 2 rather than either one of the joint surfaces 9a and 9c. Is disposed on the outer periphery of the side of the electrolyte membrane 2 so as to be formed inside the electrolyte membrane 2 with respect to both the joining surfaces 9a and 9c. Due to the presence of the reinforcing member 3b, the MEA is sandwiched between the separators 10a and 10c and the MEA is the same as described for the material having a higher compression modulus than that of the electrolyte membrane 2. It is possible to prevent the occurrence of a short circuit by suppressing the collapse of the film during hot pressing of each constituent layer.

[0033] In addition, when MEA is sandwiched between separators 10a and 10c and each MEA component layer is hot-pressed, stress is particularly concentrated on joint surfaces 9a and 9c. Therefore, as shown in FIG. 5A, the reinforcing member 3b is disposed from the end of the electrolyte membrane 2 to the inside of the joint surfaces 9a and 9c where the stress is concentrated, so that the electrolyte membrane 2 Crushing can be effectively prevented. In the present invention, as shown in FIG. 5B, the thickness of the joining surface 9a between the gas diffusion layer 5a on the anode side and the gasket 6a, and the joining surface 9c between the gas diffusion layer 5c on the force sword side and the gasket 6c. It is preferable that the position in the direction is shifted mutually. This is because the stress applied to the joint surfaces 9a and 9c is dispersed when the MEA is sandwiched between the separators and the MEA constituent layers are hot-pressed, and the breakage of the electrolyte membrane 2 can be more effectively prevented. In such a case, as shown in FIG. 5B, it is preferable to dispose the reinforcing member 3b on the inner side of the joining surfaces 9a and 9c of the end portion force of the electrolyte membrane 2 as well.

In the present invention, as the material constituting the reinforcing member 3b, a material having higher strength than the electrolyte membrane 2 can be used as appropriate. For example, the reinforcing member 3b is made of polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), which may be composed of a material force different from that of the constituent material of the electrolyte membrane 2. ) And Kapton. Among these, kabuton can be preferably used from the viewpoint of cost. In the present application, “high strength” means high mechanical strength such as compressive strength and tensile strength.

[0035] Further, the reinforcing member 3b may include a polymer electrolyte similar to the electrolyte membrane 2 described above. For example, the reinforcing member 3b may be manufactured by filling a porous body with an electrolyte. The porous material that can be used in this case can be appropriately selected from polymer materials such as polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), polyimide, polyolefin, and polysulfone. Of these, a porous material having a fluorine-based polymer material such as polytetrafluoroethylene (PTFE) or poly (vinylidene fluoride) (PVDF) is preferably used. In particular, from the viewpoint of chemical resistance and quality stability, a porous body having a polytetrafluoroethylene (PT FE) force is more preferably used, and the porosity of the porous body constituting the reinforcing member 3b is easy to manufacture. It can be appropriately set in consideration of the desired strength and the like, but is preferably 20 to 80%. [0036] The reinforcing member 3b may be formed of a material having an adhesive ability, particularly a heat-sealing ability! That is, in the present invention, the reinforcing member 3b (water vapor seal member 3a) and the adhesive layers 7a and 7c may be integrally formed, and the adhesive portions 7a and 7c may be formed in the reinforcing member 3b. By using the reinforcing member 3b formed of such a material, particularly when the MEA is assembled by the transfer method, the reinforcing member 3b exhibits the adhesive ability during hot pressing, and therefore the reinforcing member 3b and the electrolyte membrane 2 are used. Thus, the adhesion between the catalyst layers 4a and 4c and the gaskets 6a and 6c can be further improved. Such a reinforcing member 3b is preferably such that the reinforcing member 3b exhibits adhesive ability at the time of hot pressing. For example, the reinforcing member 3b preferably exhibits adhesive ability at 100 to 200 ° C. . As such a reinforcing member 3b, specifically, a fiber knitted into a desired shape, for example, a sheet shape by appropriately combining fibers of low melting point resin such as olefin-based resin can be used. More specifically, as the reinforcing member 3b, low melting point resin fibers such as polypropylene (P) fiber, polyethylene (PE) fiber, modified polyolefin fiber, polytetrafluoroethylene (PTFE) fiber, glass, etc. Examples include those combined with other fibers such as fiber (GF). Further, as the reinforcing member 3b, a material knitted by appropriately combining polytetrafluoroethylene (PTFE) fiber, glass fiber (GF) and polypropylene (PP) fiber, for example, PTFE: GF: PP = 20: 30 : Especially preferred is a braided material with a mass ratio of 50. Further, the reinforcing member 3b is particularly preferably one knitted by appropriately combining glass fibers (GF) and polypropylene (PP) fibers, for example, one knitted at a mass ratio of GF: PP = 50: 50. In such a case, the reinforcing member 3b may be directly joined to the gaskets 6a and 6c as shown in FIG. 5C. Even in such a case, the reinforcing member 3b and the gaskets 6a and 6c can be sufficiently joined by hot pressing.

[0037] Also, in the present invention, as shown in FIG. 5D, the anode catalyst layers 4a and Z or force are strengthened with respect to the thickness direction of the reinforcing layer 3c force electrolyte membrane electrode assembly as compared with the electrolyte membrane 2. It is preferably disposed in the middle of the electrolyte membrane 2 so as to overlap at least part of the sword catalyst layer 4c. Thereby, the strength of the electrolyte membrane 2 itself can be improved. The material constituting the reinforcing layer 3c is not particularly limited as long as it has proton conductivity and can improve the strength of the electrolyte membrane 2, but is manufactured by filling an electrolyte in a porous body, etc. The porous body and the electrolyte are described in the reinforcing member 3b. You can use the same ones. The thickness of the reinforcing layer 3c varies depending on the thickness and type of the electrolyte membrane, desired strength, etc., and is not particularly limited, but is preferably about 10 to 50% of the thickness of the electrolyte membrane. Further, considering the strength of the electrolyte membrane and the like, the position of the reinforcing layer 3c is preferably located substantially at the center in the thickness direction of the electrolyte membrane as shown in FIG. 5D. In FIG. 5D, the reinforcing layer 3c has a form in which the end portions of the water vapor seal member 3a are joined to each other, but the end of the water vapor seal member and the reinforcing layer 3c are not limited to such a form. There may be a gap between the two ends. Further, the reinforcing layer 3c may be intermittently disposed in the middle of the electrolyte membrane 2. Further, it may be arranged only at the center in the surface direction of the electrolyte membrane 2. However, considering the strength improvement of the electrolyte membrane 2, the reinforcing layer 3c is provided on the entire electrolyte membrane 2 and arranged so as to be joined to the end of the water vapor seal member 3a as shown in FIG. Is particularly preferred. In FIG. 5B, the force shown in the case where the reinforcing layer 3c and the reinforcing member 3b are combined is also applicable to the combination with the other water vapor sealing member 3a described above in the present invention.

In FIGS. 1A to 2B and FIGS. 4 to 5A, the joining surface 9a and the joining surface 9c are arranged at the same position in the thickness direction of the MEA. These joining surfaces are shown in FIGS. 5B to 5D. As shown, they may be located at different locations. As described above, if the joint surfaces 9a and 9c are arranged at different positions with respect to the thickness direction of the MEA, the joint surfaces 9a and 9c are sandwiched between the separators 10a and 10c and when MEA components are hot pressed. , 9c can be dispersed to alleviate the concentration of stress. For this reason, breakage due to stress of the electrolyte membrane 2 can be more effectively prevented. As a method of disposing the joining surfaces 9a and 9c at different positions with respect to the thickness direction of the MEA, it is preferable to dispose so that the area of the anode catalyst layer 4a is larger than the area of the force sword catalyst layer 4c. As a result, the area of the cathode catalyst layer 4c region facing the air existing portion downstream of the anode can be reduced, that is, the portion where the difference between the force sword potential and the electrolyte potential is large can be significantly reduced. Therefore, carbon corrosion of the force sword catalyst layer 4c can be effectively suppressed. In such a case, a structure in which almost no oxygen cross-leak from the force sword to the anode at the end of the force sword catalyst layer can occur can be obtained. The deterioration of 2 can also be effectively suppressed. Therefore, a fuel cell using an MEA having such a structure cannot be started or stopped. The performance at the time of turning and ocv can be maintained for a long time, and the fuel consumption can be improved.

[0039] In FIGS. 1A to 2B and FIGS. 4 to 5A, the adhesive layer 7a and the adhesive layer 7c are completely overlapped with the gasket 6a and the gasket 6c, respectively, in the thickness direction of the MEA. As shown in FIG. 6, the adhesive layer and the gasket may be arranged so as not to overlap each other. Even in such a case, as shown in FIG. 6A, the adhesive layers 7a and 7c are preferably arranged so that the area of the anode catalyst layer 4a is larger than the area of the force sword catalyst layer 4c. Further, in this case, as shown in FIG. 6A, the adhesive layers 7a and 7c are preferably formed so as to contact the gas diffusion layers 5a and 5c beyond the joint surfaces 9a and 9c, respectively. In this case, the adhesive layer 7c is in contact with all of the gas diffusion layer 5c, the gasket 6c, the water vapor seal member 3a, and the electrolyte membrane 2, and the adhesive layer 7a is the gas diffusion layer 5a, the gasket 6a, and the water vapor seal member 3a. As a result, the components of the MEA can be joined together with higher bondability. In addition, although the said aspect demonstrated using the example of the reinforcement member 3b, it is applicable similarly to the other water vapor | steam sealing member 3a. In addition, when the adhesive layers 7a and 7c are formed to extend over the joint surfaces 9a and 9c and below the gas diffusion layers 5a and 5c, as shown in FIG. 7B, the gasket 6a and the gas diffusion layer 5a There may be a gap between the Z and the gasket 6c and the gas diffusion layer 5c. Even in such a case, the permeation of gas can be sufficiently suppressed by the adhesive layers 7a and 7c and the water vapor seal member 3a. Note that the above description applies similarly only to the force anode side performed only on the force sword side or to both the force sword and the anode side.

[0040] In the electrolyte membrane-electrode assembly of the present invention, an anode catalyst layer 4a, a force sword catalyst layer 4c, gaskets 6a and 6c, and gas diffusion layers 5a and 5c are sequentially formed on the electrolyte membrane 2 in an appropriate arrangement. Manufactured by a method. Examples of the method for producing the electrolyte membrane / electrode assembly according to the present invention by the transfer method include the following (i) to (V).

[0041] (i) The catalyst ink is applied on the transfer mount to form the catalyst layer on the anode side and the force sword side, respectively, and the side outer peripheral portion thereof is a water vapor seal member. After sandwiching the electrolyte membrane sealed with, perform hot pressing, and then peel off the transfer mount to obtain a stack of anode catalyst layer and electrolyte membrane first sword catalyst layer, and gas on each catalyst layer After disposing the diffusion layer, an adhesive layer and a gasket are formed on the electrolyte membrane, respectively. Method for obtaining the MEA of the invention.

(Ii) A catalyst ink is formed on the gas diffusion layer by forming a catalyst layer on each of the anode side and the force sword side. After sandwiching the electrolyte membrane sealed with, hot pressing is performed to obtain a laminate of the gas diffusion layer, catalyst layer and electrolyte membrane, and then an adhesive layer and a gasket are formed on the electrolyte membrane, respectively. How to get Ming MEA.

(Iii) After forming the gas diffusion layer and the gasket on the transfer mount, the catalyst ink is applied on the gas diffusion layer to form the catalyst layer, and the adhesive layer is formed on the gasket to form a laminate. The anode laminate and the force sword laminate obtained in this way were sandwiched between the electrolyte membranes whose lateral outer peripheral portions were sealed with a water vapor seal member, and then hot-pressed, Thereafter, the transfer mount is peeled off to obtain the MEA of the present invention.

[0044] (iv) After forming the gas diffusion layer on the transfer mount, the catalyst ink is applied on the gas diffusion layer to form the catalyst layer, and then the gasket and the remaining portion of the transfer mount are formed. Adhesive layers are sequentially formed to obtain a laminate, and the anode laminate and the cathode laminate obtained in this manner sandwich an electrolyte membrane whose lateral outer periphery is sealed with a water vapor seal member. Then, hot pressing is performed, and then the transfer mount is peeled off to obtain the MEA of the present invention.

(V) After sequentially forming a gasket and an adhesive layer on the transfer mount, a gas diffusion layer is formed on the remaining portion of the transfer mount, and a catalyst ink is applied onto the gas diffusion layer. Thus, a catalyst layer is formed to obtain a laminate, and an electrolyte membrane having two anode laminates and cathode laminates obtained in this manner and having a lateral outer periphery sealed with a water vapor seal member is formed. A method of obtaining the MEA of the present invention by performing hot pressing after nipping and then peeling off the transfer mount.

Hereinafter, the method (i) will be described in detail. In the method (i), (a) for the anode side and the cathode side, a catalyst ink is applied on a transfer mount to form a catalyst layer, whereby anode and force sword transfer sheets are obtained. (B) The anode and force sword transfer sheet formed in (a) is sandwiched between the electrolyte membranes whose outer periphery is sealed with a water vapor seal member, and then hot-pressed, and then a transfer mount By stripping the anode Catalyst layer After obtaining a laminate of electrolyte sword catalyst layer (c) Disposing a gas diffusion layer (GDL) on each catalyst layer to obtain a laminate of gas diffusion layer, catalyst layer and electrolyte membrane (D) An adhesive layer and a gasket are respectively formed on the electrolyte membrane to obtain the MEA of the present invention.

[0047] First, in step (a), a catalyst ink is prepared, and this catalyst ink is coated on a transfer mount and dried to obtain a transfer sheet having a catalyst layer formed on the transfer mount. In this case, a PTFE (polytetrafluoroethylene) sheet, a PET (polyethylene terephthalate) sheet, a polyester sheet, or the like can be used as a transfer mount. The transfer mount is appropriately selected according to the type of catalyst ink to be used (particularly, a conductive carrier such as carbon in the ink).

[0048] The catalyst ink used in the above method includes a solvent, an electrolyte, and a catalyst component. The catalyst component used in the force sword catalyst layer is not particularly limited as long as it has a catalytic action in the oxygen reduction reaction. Further, the catalyst component used in the anode catalyst layer is not particularly limited as long as it has a catalytic action for the oxidation reaction of hydrogen. Specifically, metals such as platinum, ruthenium, iridium, rhodium, palladium, osmium, tungsten, lead, iron, chromium, cobalt, nickel, manganese, vanadium, molybdenum, gallium, aluminum, and alloys thereof Etc. are selected. Of these, those containing at least platinum are preferred in order to improve catalyst activity, poisoning resistance to carbon monoxide, and the like, and heat resistance. The composition of the alloy is such that the force depending on the type of metal to be alloyed is 30 to 90 atomic% for platinum and 10 to 70 atomic% for the metal to be alloyed. When an alloy is used in a force sword catalyst, the composition of the alloy varies depending on the type of metal to be alloyed, etc., and can be appropriately selected by those skilled in the art. 70 atomic% is preferable. In general, an alloy is a generic term for a metal element having one or more kinds of other metal elements or non-metal elements and having metallic properties. The alloy structure includes eutectic alloys, which are so-called mixtures in which the constituent elements become separate crystals, those in which the constituent elements are completely melted into a solid solution, and the constituent elements are intermetallic compounds or compounds of metals and nonmetals. In the present application, any of them may be used. At this time, the catalyst component used for the force sword catalyst layer and the catalyst component used for the anode catalyst layer can be appropriately selected from the above. In the following description, unless otherwise noted The descriptions of the catalyst components for the sword catalyst layer and the anode catalyst layer are the same for both, and are collectively referred to as “catalyst components”. However, the catalyst components for the force sword catalyst layer and the anode catalyst layer do not need to be the same, and are appropriately selected so as to exhibit the desired action as described above.

[0049] The shape of the catalyst component is preferably granular. At this time, the smaller the average particle diameter of the catalyst particles used in the catalyst ink, the higher the effective electrode area where the electrochemical reaction proceeds, which is preferable because the oxygen reduction activity increases. On the other hand, there is a phenomenon that the oxygen reduction activity decreases. Therefore, the average particle diameter of the catalyst particles contained in the catalyst ink is preferably 1 to 30 nm, more preferably 1.5 to 20 nm, even more preferably 2 to: LOnm, particularly preferably 2 to 5 nm. . From the viewpoint of easy loading, it is preferably 1 nm or more, and from the viewpoint of catalyst utilization, it is preferably 30 nm or less. The “average particle diameter of the catalyst particles” in the present invention is the average value of the particle diameter of the catalyst component determined from the crystallite diameter or transmission electron microscopic image obtained from the half width of the diffraction peak of the catalyst component in X-ray diffraction. Can be measured.

[0050] In the present invention, the catalyst particles described above are supported on a conductive carrier and are included in the catalyst ink as an electrode catalyst.

[0051] The conductive carrier is not particularly limited as long as it has a specific surface area for supporting the catalyst particles in a desired dispersed state and has sufficient electronic conductivity as a current collector. The component is preferably carbon. Specific examples include powerful carbon particles such as carbon black, activated carbon, coatus, natural graphite, and artificial graphite. In the present invention, “the main component is carbon” refers to containing a carbon atom as a main component, and is a concept including both a carbon atom and substantially a carbon atom. In some cases, elements other than carbon atoms may be included to improve the characteristics of the fuel cell. Note that “substantially carbon nuclear power” means that the inclusion of impurities of about 2 to 3% by mass or less is allowed.

[0052] The BET specific surface area of the conductive carrier may be a specific surface area sufficient to carry the catalyst component in a highly dispersed state, but is preferably 20 to 1600 m ² Zg, more preferably 80 to 1200 m ² Zg. . When the specific surface area is 20 m ² Zg or more, the catalyst component in the conductive support is formed. Therefore, sufficient power generation performance can be obtained without lowering the dispersibility of the electrolyte component and the electrolyte component described later, and if it is 1600 m ² Zg or less, the effective utilization rate of the catalyst component and the electrolyte component can be avoided from decreasing.

[0053] In addition, the size of the conductive carrier is preferably 5 to 200 nm in average particle diameter from the viewpoint of easy loading, catalyst utilization, and catalyst layer thickness control within an appropriate range. Should be around 10 ~ lOOnm! /.

[0054] In the electrode catalyst in which the catalyst component is supported on the conductive support, the supported amount of the catalyst component is preferably 10 to 80% by mass, more preferably 30 to 30%, based on the total amount of the electrode catalyst. 70% by mass is recommended. When the loading amount is 80% by mass or less, the degree of dispersion of the catalyst component on the conductive carrier does not decrease, and when the loading amount increases, the power generation performance is greatly improved and the economic advantage does not decrease. . In addition, when the supported amount is 10% by mass or more, a large amount of electrode catalyst is not required to obtain a desired power generation performance without lowering the catalytic activity per unit mass. The amount of catalyst component supported can be measured by inductively coupled plasma emission spectroscopy (ICP).

[0055] In addition, catalyst components supported on a conductive carrier include impregnation method, liquid phase reduction support method, evaporation to dryness method, colloid adsorption method, spray pyrolysis method, reverse micelle (microemulsion method), etc. The method can be used.

[0056] The force sword catalyst layer and the anode catalyst layer of the present invention may contain a polymer electrolyte in addition to the electrode catalyst. As the polymer electrolyte, the same polymer electrolyte as that used for the electrolyte membrane can be used. The polymer electrolyte used for the electrolyte membrane and the polymer electrolyte used for each catalyst layer may be the same or different, but from the viewpoint of improving the adhesion between each catalyst layer and the electrolyte membrane. It is preferable to use the same one. In other words, the polymer electrolyte may be a member having at least high proton conductivity. The polymer electrolyte that can be used in this case is roughly classified into a fluorine-based electrolyte containing fluorine atoms in all or part of the polymer skeleton and a hydrocarbon-based electrolyte containing no fluorine atoms in the polymer skeleton.

[0057] Specific examples of the fluorine-based electrolyte include perfluorocarbons such as naphthion (manufactured by DuPont), Aciplex (manufactured by Asahi Kasei Co., Ltd.), and Flemion (manufactured by Asahi Glass Co., Ltd.). Sulfonic acid polymer, polytrifluorostyrene sulfonic acid polymer, perfluorocarbon phosphonic acid polymer, trifluorostyrene sulfonic acid polymer, ethylene tetrafluoroethylene g-styrene sulfonic acid polymer, ethylene tetrafluoro Preferable examples include an ethylene copolymer and a polyvinylidene fluoride perfluorocarbon sulfonic acid polymer.

[0058] Specific examples of the hydrocarbon electrolyte include polysulfone sulfonic acid, polyaryl ether ketone sulfonic acid, poly benzimidazole alkyl sulfonic acid, poly benzimidazole alkyl phosphonic acid, polystyrene sulfonic acid, polyether ether ketone. Examples of suitable examples include sulfonic acid and polyphenyl sulfonic acid.

[0059] Since the polymer electrolyte is excellent in heat resistance, chemical stability and the like, it is preferable to include a fluorine atom, among which fluorine-based electrolytes such as naphthion, aciplex, and flemion are preferable.

[0060] In the method of the present invention, a catalyst layer is formed by applying a catalyst ink comprising the above-described electrode catalyst, polymer electrolyte and solvent to the gas diffusion layer. In this case, as the solvent, a normal solvent used for forming the catalyst layer can be used in the same manner. Specifically, water, lower alcohols such as cyclohexanol, ethanol and 2-propanol can be used. The amount of the solvent used is any amount in the catalyst ink as long as the electrode catalyst can sufficiently exhibit the desired catalytic action for the hydrogenation reaction (anode side) and the oxygen reduction reaction (power sword side). But you can. Specifically, it is preferable that the electrode catalyst is present in an amount such that it is 5 to 30% by mass, more preferably 9 to 20% by mass in the catalyst ink.

[0061] The catalyst ink of the present invention may contain a thickener. The use of a thickener is effective in cases where the catalyst ink cannot be successfully applied onto the gas diffusion layer! Examples of the thickener that can be used in this case include glycerin, ethylene glycol (EG), polybulal alcohol (PVA), and propylene glycol (PG). The addition amount of the thickener is preferably 5 to 20% by mass with respect to the total mass of the catalyst ink as long as it is an amount that does not hinder the above effect of the present invention.

[0062] The catalyst ink of the present invention comprises an electrode catalyst, an electrolyte and a solvent, and water repellent if necessary. The preparation method is not particularly limited as long as a functional polymer and z or a thickener are appropriately mixed. For example, a catalyst ink can be prepared by adding an electrolyte to a polar solvent, heating and stirring the mixture, dissolving the electrolyte in the polar solvent, and then adding an electrode catalyst thereto. Alternatively, after the electrolyte is once dispersed and suspended in a solvent, the dispersion Z suspension may be mixed with an electrode catalyst to prepare a catalyst ink. In addition, a commercially available electrolyte solution (for example, a DuPont Nafion solution: Nafion dispersed and suspended at a concentration of 5 wt% in 1 propanol) is prepared in advance in the above-mentioned other solvent. You may use for the said method as it is.

[0063] The catalyst ink as described above is applied onto a transfer mount to form each catalyst layer. At this time, as a condition for forming the force sword Z anode catalyst layer on the transfer mount, the catalyst ink was applied on the transfer mount so that the thickness after drying was 5 to 20 / ζ πι, Dry in a vacuum dryer or under reduced pressure. At this time, the drying temperature is preferably 25 to 150 ° C, preferably 60 to 120 ° C, and the drying time is preferably 5 to 30 minutes, preferably 10 to 20 minutes. In the above step, if the thickness of the catalyst layer is not sufficient, the coating / drying step is repeated until the desired thickness is reached.

[0064] Next, in the step (b), the anode and force sword transfer sheet formed in the above (a) is sandwiched between the electrolyte membranes whose lateral outer peripheral portions are sealed with a water vapor seal member, Then, the transfer mount is peeled off to obtain an anode catalyst layer-electrolyte membrane-forced sword catalyst layer laminate. At this time, the hot press conditions are not particularly limited as long as the catalyst layer, the adhesive layer, and the electrolyte membrane can be joined sufficiently closely, but 100-200. C, more preferably 110 to 170 ° C., and preferably 1 to 5 MPa with respect to the electrode surface. Thereby, the bondability between the polymer electrolyte membrane and the catalyst layer can be enhanced. After performing the hot press, a laminate of the catalyst layer and the electrolyte membrane can be obtained by removing the transfer mount.

[0065] In step (c), a gas diffusion layer (GDL) is disposed on each of the anode and the force sword catalyst layer to obtain a laminate of the gas diffusion layer, the catalyst layer, and the electrolyte membrane. Specifically, the laminate (b) is further sandwiched between gas diffusion layers, and if necessary, sandwiched and joined by hot pressing. At this time, as the gas diffusion layer, carbon fabric, paper-like paper, felt, etc. Non-woven fabrics, and materials based on sheet-like materials having electrical conductivity and porosity are exemplified. The thickness of the substrate may be appropriately determined in consideration of the characteristics of the gas diffusion layer to be obtained, but is preferably 30 to 500 μm in view of mechanical strength and gas and water permeability. More preferably, it is 50-300 micrometers.

[0066] The gas diffusion layer preferably contains a water repellent in the base material for the purpose of further improving water repellency and preventing a flooding phenomenon or the like. Examples of the water repellent include fluorine such as polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), polyhexafluoropropylene, and tetrafluoroethylene monohexafluoropropylene copolymer (FEP). Polymer materials such as polypropylene, polypropylene, and polyethylene.

[0067] Further, in order to further improve the water repellency, the gas diffusion layer may have a carbon particle layer having an aggregate strength of carbon particles containing a water repellent on the substrate.

[0068] As the carbon particles, carbon black, graphite, expanded graphite and the like can be used.

Of these, carbon blacks such as oil furnace black, channel black, lamp black, thermal black, and acetylene black are preferred because of their excellent electron conductivity and large specific surface area. The particle size of the carbon particles is preferably about 10 to: LOOnm. As a result, high drainage by capillary force is obtained, and contact with the catalyst layer can be improved.

[0069] Examples of the water repellent used in the carbon particle layer include the same water repellents as those used in the substrate. Of these, fluorine-based polymer materials are preferably used because of their excellent water repellency and corrosion resistance during electrode reaction.

[0070] In the carbon particle layer, the mixing ratio of the carbon particles to the water repellent may not provide water repellency as expected if there are too many carbon particles. Conductivity may not be obtained. Considering these, the mixing ratio of the carbon particles and the water repellent in the carbon particle layer is preferably about 90:10 to 40:60 in terms of mass ratio.

[0071] The thickness of the carbon particle layer may be appropriately determined in consideration of the water repellency of the obtained gas diffusion layer.

[0072] As a method of adding a water repellent to the gas diffusion layer, the base material used for the gas diffusion layer is repellent. For example, a method of heating and drying in an oven or the like after dipping in a liquid dispersion of a liquid medicine.

[0073] In the case of forming a carbon particle layer on a transfer mount in the gas diffusion layer, first, a bonbon particle, a water repellent, etc. are added to water, perfluorobenzene, dichloropentafluoropropan, A slurry is prepared by dispersing in an alcohol solvent such as methanol or ethanol. Then, the slurry is applied on a transfer mount and dried, or the slurry is dried and pulverized to form a powder, which is coated on the gas diffusion layer. Thereafter, heat treatment is preferably performed at about 250 to 400 ° C. using a pine furnace or a baking furnace.

Subsequently, in step (d), an adhesive layer and a gasket are respectively formed at predetermined positions of the electrolyte membrane. In this case, the material that can be used for the adhesive layer is not particularly limited as long as the electrolyte membrane and the gasket can be adhered closely, but hot melt adhesives such as polyolefin, polypropylene, and thermoplastic elastomer, acrylic adhesives, and the like. Agents, olefin-based adhesives such as polyester and polyolefin can be used. When the water vapor seal member is formed of an adhesive, the water vapor seal member and the adhesive used for the adhesive layer may be the same or different. When the adhesive used for the water vapor seal member and the adhesive layer is the same, as shown in FIG. 7, in the above (c), an electrolyte membrane having no water vapor seal member is used. In step d), a step of forming a water vapor sealing member at a predetermined portion of the electrolyte membrane and a step of forming an adhesive layer may be performed. The thickness of the adhesive layer is not particularly limited as long as sufficient adhesion with the electrolyte membrane and the gasket can be achieved, but it is 5 to 30 μm, more preferably 10 to 25 μm. That is preferable

[0075] Thereafter, a gasket is formed on the adhesive layer so as to be in contact with the end portion of the gas diffusion layer, possibly with a gap. At this time, the gasket is composed of a material cover which is impermeable to gas, particularly oxygen gas, hydrogen gas and water vapor. The gas-impermeable material that can be used is not particularly limited as long as it is impermeable to oxygen or hydrogen gas when formed into a film. Specific examples include polyethylene naphthalate (PEN), polyethylene terephthalate (PET), polytetrafluoroethylene (PTFE), and poly (vinylidene fluoride) (PVDF). As a method for forming the gasket, the gas as described above is formed on the adhesive layer. A method can be used in which an impermeable material is applied to a predetermined thickness and cured by heating at 25 to 150 ° C. for 10 seconds to 10 minutes. Alternatively, a gas impermeable material may be formed into a sheet shape in advance, and the sheet bonded to the adhesive layer may be disposed on the electrolyte membrane. At this time, the thickness of the gasket is not limited as long as it can exhibit a sufficient gas sealing property. However, for example, in the polymer electrolyte fuel cell, as described above, the convex portions 8a and 8c are formed on the gasket and further sandwiched by the separator. At this time, the convex portions 8a and 8c are subjected to compressive stress. . Here, by setting the height of the gasket before being sandwiched by the separator to be lower than the height of the gas diffusion layer, the adhesion between the separator and the gas diffusion layer is improved, and the fuel flow path and the oxidant flow path are ensured. In addition, the conductivity of the gas diffusion layer and the separator can be secured. For this reason, the gasket is preferably formed so as to be lower than the height of the gas diffusion layer. For this reason, the thickness of the gasket is more preferably 10 to 200 μm, particularly preferably 15 to 40 μm.

In the above description, the method for forming the anode catalyst layer and the force sword catalyst layer on the electrolyte membrane by the transfer method has been described. However, the MEA of the present invention directly prints the catalyst ink on the electrolyte membrane. It may be manufactured by other methods such as a coating method. That is, it is only necessary to form the catalyst layer, the gas diffusion layer, the adhesive layer, and the gasket on the surfaces of the anode and the force sword on the electrolyte membrane whose lateral outer peripheral portion is sealed with the water vapor seal member. The details of each step can be applied to the same method as described above, and thus the description thereof is omitted here.

[0077] As described above, the electrolyte membrane-electrode assembly of the present invention suppresses drying of the electrolyte membrane due to water vapor permeation, and effectively breaks the membrane due to compressive stress at the joint surface between the gas diffusion layer and the gasket. It is possible to suppress. Therefore, by using a strong electrolyte membrane-electrode assembly, it is possible to provide a highly reliable fuel cell that has a simple manufacturing process and excellent durability.

[0078] As the type of the fuel cell, the polymer electrolyte fuel cell has been described above as an example, but in addition to this, an acid electrolyte represented by an alkaline fuel cell and a phosphoric acid fuel cell is also used. Fuel cells, direct methanol fuel cells, micro fuel cells, and the like. Above all, the polymer electrolyte fuel is small, high density and high output is possible. A battery is preferable. Also, the fuel cell is a power source that is useful as a stationary power source in addition to a power source for moving vehicles such as vehicles with limited mounting space. Especially in automotive applications where system start-up and output fluctuations frequently occur. It can be particularly preferably used.

[0079] The polymer electrolyte fuel cell is useful as a power source for a mobile object such as an automobile in which a mounting space is limited in addition to a stationary power source. In particular, the movement of automobiles and the like that are susceptible to corrosion of the carbon support due to the high output voltage required after a relatively long shutdown, and the deterioration of the polymer electrolyte due to the high output voltage being taken out during operation. It is particularly preferred to be used as a body power source.

[0080] The fuel cell generally has a structure in which MEA is sandwiched between separators.

[0081] The separator can be used without limitation, such as those made of carbon such as dense carbon graphite and carbon plate, or made of metal such as stainless steel. The separator has a function of separating air and fuel gas, and a flow channel groove for securing such a gas flow channel may be formed. The thickness and size of the separator, the shape of the channel groove, etc. should be determined appropriately in consideration of the output characteristics of the resulting fuel cell.

[0082] Furthermore, a stack in which a plurality of MEAs are stacked and connected in series via a separator may be formed so that the fuel cell can obtain a desired voltage or the like. The shape of the fuel cell is not particularly limited, and may be determined as appropriate so that desired battery characteristics such as voltage can be obtained.

[0083] The entire contents of Japanese Patent Application No. 2005-252636 (Application No .: August 31, 2005) and Japanese Patent Application No. 2006-229496 (Application Date: Aug. 25, 2006) are incorporated herein by reference.

The contents of the present invention have been described above in accordance with the embodiments and examples. However, the present invention is not limited to these descriptions, and various modifications and improvements can be made. It is self-evident to the operator.

Industrial applicability

[0085] According to the present invention, water vapor permeation from the surface direction of the electrolyte membrane can be prevented, and drying of the electrolyte membrane can be effectively prevented. For this reason, the electrolyte membrane-electrode assembly having the structure according to the present invention is excellent in durability because it does not dry and the phenomenon that the humidity in the external atmosphere rises excessively does not occur. In addition, by disposing the water vapor seal member in the part where the compressive stress is easily applied, the electrolyte membrane is prevented from being crushed or broken, so that the electrolyte can be applied by joining the MEA layers by hot pressing or by the fastening pressure when assembling the battery. It is possible to effectively suppress the deterioration of the film over time.

Claims

The scope of the claims

[1] an electrolyte membrane;

An anode catalyst layer provided on one surface of the electrolyte membrane;

A force sword catalyst layer provided on the other surface of the electrolyte membrane;

A seal for preventing gas leakage from the side surface of the anode catalyst layer and the side surface of the force sword catalyst layer, and the side surface of the electrolyte membrane;

A gasket provided on both sides of the seal,

A part of the seal forms an adhesive part for adhering the electrolyte membrane and the gasket, and the adhesive part is formed on the outer periphery of the anode catalyst layer and the force sword catalyst layer in the surface direction of the anode catalyst layer. An electrolyte membrane-one-electrode assembly arranged so as to prevent gas leakage due to side force of the side surface and force sword catalyst layer.

[2] The seal is disposed so as to include at least a part of the outermost peripheral portion of the electrolyte membrane.

The electrolyte membrane electrode assembly according to claim 1.

[3] The seal includes a water vapor seal member that prevents leakage of gas due to side force of the electrolyte membrane, and an adhesive layer that adheres the water vapor seal member or the electrolyte layer and the gasket.

3. The electrolyte membrane electrode joint according to claim 1, wherein the water vapor seal member is disposed at a position corresponding to a portion where a reaction force is applied to the gasket in the thickness direction of the electrolyte membrane electrode assembly. body.

[4] The seal includes a water vapor seal member that prevents leakage of gas due to side force of the electrolyte membrane, and an adhesive layer that bonds the water vapor seal member or the electrolyte layer and the gasket,

The electrolyte membrane electrode according to any one of claims 1 to 3, wherein the water vapor seal member is formed by impregnating the electrolyte membrane with an adhesive, or formed by disposing an adhesive member between the gaskets. Joined body.

[5] The seal adheres the water vapor seal member for preventing leakage of gas due to side force of the electrolyte membrane, and the water vapor seal member or the electrolyte layer and the gasket. An adhesive layer,

5. The electrolyte membrane / electrode assembly according to claim 1, wherein the water vapor sealing member is made of a material having a higher compression elastic modulus than the electrolyte membrane.

6. The electrolyte membrane / electrode assembly according to claim 5, wherein the water vapor seal member is made of the same material as the material constituting the gasket.

7. The electrolyte membrane-electrode assembly according to claim 6, wherein the water vapor seal member and the gasket are integrally formed.

[8] A first gas diffusion layer further formed on the anode catalyst layer and a second gas diffusion further formed on the force sword catalyst layer with respect to the thickness direction of the electrolyte membrane electrode assembly. And further comprising a layer,

The seal prevents leakage of gas having a side force of the electrolyte membrane, and has a reinforcing member having higher strength than the electrolyte membrane, and an adhesive layer that bonds the water vapor seal member or the electrolyte layer and the gasket. Consists of

The reinforcing member is formed on the inner side of the electrolyte membrane than either the joint surface between the first gas diffusion layer and the gasket or the joint surface between the second gas diffusion layer and the gasket. The electrolyte membrane electrode assembly according to claim 1.

[9] The electrolyte membrane is arranged in the middle of the electrolyte membrane so as to overlap at least part of the anode catalyst layer or the sword catalyst layer with respect to the thickness direction of the electrode assembly, and more than the electrolyte membrane. The electrolyte membrane-electrode assembly according to claim 1, further comprising a high-strength reinforcing layer.

10. The electrolyte membrane / electrode assembly according to claim 1, wherein an area of the anode catalyst layer is larger than an area of the force sword catalyst layer.

[11] A fuel cell comprising the electrolyte membrane electrode assembly according to any one of claims 1 to 10.