JP2007095669A - Electrolyte film-electrode assembly - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrolyte film-electrode assembly with improved durability, restraining and preventing the electrolyte film from dry-up. <P>SOLUTION: The electrolyte film-electrode assembly 1 is composed of the electrolyte film 2, an anode catalyst layer 4a formed on one face of the electrolyte film, a cathode catalyst layer 4c formed on the other face of the electrolyte film, seals 3, 7a, 7c preventing gas leakage from side faces of the anode catalyst layer, the anode catalyst layer, and the electrolyte film, and gaskets 6a, 6c arranged on both faces of the seals. A part of the seal forms adhesion parts (adhesion layers) 7a, 7c adhering the electrolyte film 2 to the gaskets 6a, 6c. The adhesion parts (adhesion layers) 7a, 7c are arranged at outer peripheral part in planar direction of the anode catalyst layer 4a and the cathode catalyst layer 4c so as to prevent gas leakage from side faces of the anode catalyst layer 4a and the cathode catalyst layer 4c. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

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

  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 an electrode reaction is water in principle and has almost no adverse effect on the global environment. In particular, the polymer electrolyte fuel cell is expected as a power source for electric vehicles because it operates at a relatively low temperature. In general, the polymer electrolyte fuel cell has a structure in which an electrolyte membrane-electrode assembly is sandwiched between a gas diffusion layer and a separator. The electrolyte membrane-electrode assembly is obtained by sandwiching a polymer electrolyte membrane between a pair of electrode catalyst layers.

In the polymer electrolyte fuel cell having the 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 ₂ → 4H ⁺ + 4e ⁻ ). Next, the generated protons pass through the solid polymer electrolyte contained in the anode-side electrode catalyst layer and the polymer electrolyte membrane in contact with the anode-side electrode catalyst layer, and reach the cathode-side electrode catalyst layer. Further, the electrons generated in the anode side electrode catalyst layer include a conductive carrier constituting the anode side electrode catalyst layer, a gas diffusion layer in contact with a side different from the polymer electrolyte membrane of the anode side electrode catalyst layer, The cathode side electrode catalyst layer is reached through the separator and the external circuit. The protons and electrons that have reached the cathode-side electrode catalyst layer react with oxygen contained in the oxidant gas supplied to the cathode side to generate water (O ₂ + 4H ⁺ + 4e ⁻ → 2H ₂ O). In the fuel cell, electricity can be taken out through the above-described electrochemical reaction.

  Conventionally, various studies have been made on the structure of such an MEA.

  For example, in a solid polymer electrolyte fuel cell, conventionally, a gap is maintained around the electrode catalyst layer so that fuel gas and oxidant gas in the gas supply groove do not leak to the outside through the laminated surface of the MEA. The gas seal portion was provided in the shape of a frame, but such a gap portion is susceptible to mechanical stress due to the differential pressure of the reaction gas applied to the solid polymer electrolyte membrane and the creep of the membrane, and the solid polymer electrolyte membrane There was a problem of being damaged. In order to solve this problem, it has been reported that a reinforcing film / protective film is disposed in a gap between the electrode catalyst layer and the gas sealing material, which are easily damaged (Patent Documents 1 and 2).

In addition, in a conventional polymer electrolyte fuel cell, a gap is formed between the separator and the gasket layer, and fuel or oxidant gas leaks, resulting in a decrease in performance, and sufficient adhesion between the separator and the electrode is ensured. In some cases, desired power generation characteristics may not be exhibited. Therefore, in order to solve such a problem, in a single cell in which an electrolyte membrane-electrode assembly having a gasket layer is sandwiched between separators, the thickness of the gasket layer (gas seal) before sandwiching with the separator is set to the thickness of the electrode. A single cell having a thickness smaller than the thickness is disclosed (Patent Document 3). According to Patent Document 3, by optimizing the thickness of the electrode and the gasket layer, the adhesion between the separator and the gas diffusion electrode is improved, and the fuel flow path and the oxidant flow path are reliably formed. It is an object of the present invention to provide a polymer electrolyte fuel cell that can secure conductivity of a gas diffusion electrode and a separator and can exhibit excellent power generation characteristics.
JP-A-5-2442897 Japanese Patent Laid-Open No. 5-21077 JP 2002-324556 A

  However, in the MEA disclosed in Patent Documents 1 to 3, a reinforcing film / protective film (Patent Documents 1 and 2) and a gas seal (Patent Document 3) are provided on the surface around the electrolyte membrane in order to prevent gas leakage. However, the side surface of the electrolyte membrane is open and no gas seal structure is provided. For this reason, as described above, a part of the water generated on the cathode electrode catalyst layer side is discharged to the outside as a gas (water vapor) through the side surface of the electrolyte membrane, and due to the presence of the generated water on the cathode electrode catalyst layer side. The electrolyte membrane cannot be maintained in a moderately moist state. For this reason, in such a structure, the electrolyte membrane is dried and the strength is lowered, or the humidity of the external atmosphere is raised, and the durability and power generation performance of the MEA are lowered. There was a problem.

  Therefore, the present invention has been made in view of the above circumstances, and an object thereof is to provide an electrolyte membrane-electrode assembly in which drying of the electrolyte membrane is suppressed / prevented 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.

  As a result of diligent research to solve the above problems, the inventors of the present invention formed a gasket on the surface of the electrolyte membrane corresponding to the outer peripheral portion of the cathode catalyst layer and the anode catalyst layer, and at the same time the side surface portion of the electrolyte membrane (outer periphery). Gas) from the direction of the electrolyte membrane surface (oxygen, hydrogen and water vapor) by providing a seal that prevents gas leakage from the side surface of the catalyst layer and the side surface of the electrolyte membrane at any part located between the gasket and the gasket. It has been found that gas leakage prevention functions such as leakage, gas from the side surface of the catalyst layer and the side surface of the electrolyte membrane, in particular, transpiration (permeation) of water vapor, can be effectively prevented by the gasket and the seal. MEA having excellent durability because the electrolyte membrane does not dry and the humidity of the external atmosphere does not rise excessively. It has been found to become. In addition, the water vapor sealing member that prevents the gas from leaking from the side surface of the electrolyte membrane and the water vapor sealing member or the electrolyte layer and the gasket are adhered to the seal to prevent gas leakage from the side surface of the catalyst layer. A lip composed of an adhesive portion (adhesive layer) to prevent and compressing the water vapor seal member (part arranged to prevent gas leakage from the side surface of the electrolyte membrane) which is a part of the seal. By placing it underneath, it suppresses and prevents the electrolyte membrane from collapsing and breaking, thereby effectively suppressing deterioration of the electrolyte membrane over time due to the joining pressure of each MEA layer by hot pressing or when the battery is assembled.・ We also found that it can be prevented. Based on the above findings, the present invention has been completed.

That is, the purpose is to provide an electrolyte membrane,
An anode catalyst layer provided on one surface of the electrolyte membrane;
A cathode catalyst layer provided on the other surface of the electrolyte membrane;
Seals for preventing gas leakage from the side surfaces of the anode catalyst layer and the cathode catalyst layer, and the side surfaces of the electrolyte membrane;
A gasket provided on both sides of the seal,
A part of the seal forms an adhesive part that bonds the electrolyte membrane and the gasket,
The electrolyte membrane-electrode is disposed such that the adhesion portion can prevent gas leakage from a side surface of the anode catalyst layer and a side surface of the cathode catalyst layer at outer peripheral portions in the surface direction of the anode catalyst layer and the cathode catalyst layer. Achieved by the joined body.

  According to the present invention, water vapor permeation from the side surface of the catalyst layer and the side surface of the electrolyte membrane can be prevented, and drying of the membrane can be effectively suppressed / prevented. For this reason, the electrolyte membrane-electrode assembly having the structure according to the present invention is excellent in durability.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1A is a schematic cross-sectional view illustrating a lateral outer periphery and an outermost periphery of an electrolyte membrane in an MEA of the present invention. 1B to 1G are schematic cross-sectional views showing various exemplary embodiments of the arrangement of seals in the electrolyte membrane in the MEA of the present invention.

  1B-1G, the present invention includes an electrolyte membrane 2, an anode catalyst layer 4a provided on one surface of the electrolyte membrane 2, and a cathode catalyst provided on the other surface of the electrolyte membrane 2. Layer 4c, seals 3, 7a and 7c for preventing gas leakage from the side surfaces of anode catalyst layer 4a and cathode catalyst layer 4c, and side surfaces of electrolyte membrane 2, and both surfaces of seals 7a and 7a are provided. Gaskets 6a and 6c are provided, and a part of the seal forms adhesive portions 7a and 7c for adhering the electrolyte membrane 2 and the gaskets 6a and 6c, and the adhesive portions 7a and 7c are the anode catalyst layer. MEA1 is arranged at the outer peripheral portion in the surface direction of 4a and cathode catalyst layer 4c so as to prevent gas leakage from the side surface of anode catalyst layer 4a and the side surface of cathode catalyst layer 4c. It relates. In other words, the electrolyte membrane 2 and the gaskets 6a and 6c are bonded by the seal portions 7a and 7c, and the bonded portions (adhesive layers) 7a and 7c are connected to the anode catalyst layer 4a and the cathode catalyst layer 4c. It can also be said that it relates to the MEA 1 that is arranged on at least the same surface so as to prevent gas leakage from the side surfaces of the catalyst layers 4a, 4c.

  The electrolyte membrane 2 used in the MEA 1 of the present invention is not particularly limited, and a membrane made of a known polymer electrolyte can be used, but any member having at least high proton conductivity may be used. The polymer electrolyte that can be used in this case is roughly classified into a fluorine-based electrolyte that contains fluorine atoms in the whole or a part of the polymer skeleton and a hydrocarbon-based electrolyte that does not contain fluorine atoms in the polymer skeleton.

  Specific examples of the fluorine electrolyte include perfluorocarbon sulfonic acids such as Nafion (registered trademark, manufactured by DuPont), Aciplex (registered trademark, manufactured by Asahi Kasei Co., Ltd.), and Flemion (registered trademark, manufactured by Asahi Glass Co., Ltd.). Polymer, polytrifluorostyrene sulfonic acid polymer, perfluorocarbon phosphonic acid polymer, trifluorostyrene sulfonic acid polymer, ethylene tetrafluoroethylene-g-styrene sulfonic acid polymer, ethylene-tetrafluoroethylene copolymer, polyvinylidene A preferred example is a fluoride-perfluorocarbon sulfonic acid-based polymer.

  Specific examples of the hydrocarbon electrolyte include polysulfone, polysulfonic acid, polyaryl ether ketone sulfonic acid, polybenzimidazole alkyl sulfonic acid, polybenzimidazole alkylphosphonic acid, polystyrene sulfonic acid, polyether ether ketone sulfonic acid, poly A suitable example is phenylsulfonic acid.

  The polymer electrolyte preferably contains a fluorine atom because of its excellent heat resistance and chemical stability. Among them, Nafion (registered trademark, manufactured by DuPont), Aciplex (registered trademark, manufactured by Asahi Kasei Co., Ltd.) Fluorine electrolytes such as Flemion (registered trademark, manufactured by Asahi Glass Co., Ltd.) are preferred.

  In addition, various Nafion (registered trademark, manufactured by DuPont) manufactured by DuPont and perfluorosulfonic acid membranes represented by Flemion, ion exchange resins manufactured by Dow Chemical, ethylene-tetrafluoroethylene copolymer resin membranes, Fluoropolymer electrolytes such as resin membranes based on trifluorostyrene, and hydrocarbon polymer resin membranes with sulfonic acid groups, such as solid polymer electrolyte membranes that are generally commercially available, polymer microporous A membrane in which a membrane is impregnated with a liquid electrolyte, a membrane in which a porous body is filled with a polymer electrolyte, or the like may be used. Alternatively, the electrolyte membrane may be made of polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), or the like in addition to the above-described fluorine-based polymer electrolyte or a membrane made of a hydrocarbon resin having a sulfonic acid group. You may use what formed the porous thin film impregnated with electrolyte components, such as phosphoric acid and an ionic liquid.

  The thickness of the electrolyte membrane 2 may be appropriately determined in consideration of the characteristics of the obtained MEA 1, but is preferably 5 to 300 μm, more preferably 10 to 200 μm, and particularly preferably 15 to 100 μm. From the viewpoint of strength during film formation and durability during MEA operation, it is preferably 5 μm or more, and from the viewpoint of output characteristics during MEA operation, it is preferably 300 μm or less.

  In the embodiment of the present invention shown in FIG. 1B to FIG. 1G, the seal can prevent the leakage of gas from the side surface of the electrolyte membrane 2 (the leakage of gas from the side surface of the electrolyte membrane 2 can be prevented). 3), the water vapor seal member 3 or the electrolyte layer 2, and the gaskets 6a and 6c to prevent leakage of gas from the side surfaces of the catalyst layers 4a and 4c. (Parts arranged so as to prevent leakage of gas from the side surfaces of the catalyst layers 4a and 4c) 7a and 7c, and the steam seal member 3 as a part of the seal is interposed between the gaskets 6a and 6b. At least one part is formed. In other words, it can be said that at least a part of the water vapor seal member 3 is disposed on at least a part of the lateral outer periphery of the electrolyte membrane 2. Alternatively, it can be said that the water vapor seal member 3 is disposed so as to include at least a part of the lateral outer peripheral portion of the electrolyte membrane 2. In this case, the “lateral outer peripheral portion of the electrolyte membrane” means the entire electrolyte membrane portion (arrow portion in FIG. 1A) in contact with the gaskets 6a to 6b on at least one side of the anode catalyst layer 4a and the cathode catalyst layer 4b. . In the present invention, in addition to the water vapor seal member 3 formed in the electrolyte membrane 2 on the “electrolyte membrane portion (arrow portion in FIG. 1A)”, the water vapor seal member 3 formed separately from the electrolyte membrane 2 The gap 10, the electrolyte membrane 2 itself, and a reinforcing layer 3 ′ described later may be disposed (see FIGS. 1B to 1G, FIG. 5D, etc.). Therefore, at least one part of the water vapor seal member 3 only needs to be formed between the gaskets 6 a and 6 b on the side outer periphery of the electrolyte membrane 2. For example, (a) the water vapor seal member 3 may be formed on a part (inner side) of the electrolyte membrane 2. 1C and 1F described below correspond to this. Or (b) the water vapor sealing member separately from the electrolyte membrane 2 outside the end (outermost peripheral portion) of the electrolyte membrane 2 (in close contact with or away from the end (outermost peripheral portion) of the electrolyte membrane 2) 3 may be formed. This corresponds to FIG. 1G described below. 1B, 1D, and 1E may be formed so as to correspond to the former (a) or may be formed to correspond to the latter (b).

  For this reason, “at least a part of the water vapor seal member 3 is disposed on at least a part of the lateral outer periphery of the electrolyte membrane” means that the water vapor seal member 3 is a gasket in the lateral outer periphery of the electrolyte membrane 2. It means that it is provided so as to include at least a part of the part in contact with 6a to 6b (at least a part in the arrow part of FIG. 1A).

  In the present invention, when the anode catalyst layer 4a and the cathode catalyst layer 4c are formed at different positions, the water vapor seal member 3 has the gaskets 6a, 6a on the at least one side of the anode catalyst layer 4a and the cathode catalyst layer 4c. Although it should just be arrange | positioned in the electrolyte membrane 2 part which touches 6c, Preferably it arrange | positions in the electrolyte membrane 2 part which touches the gaskets 6a and 6c of both catalyst layers.

  That is, as the arrangement position of the water vapor seal member 3 according to the present invention, for example, as shown in FIG. 1B, when the water vapor seal member 3 is formed at the end (outermost peripheral portion) of the electrolyte membrane 2; When the water vapor seal member 3 is formed in the electrolyte membrane 2 at a position corresponding to the vicinity of the intermediate portion of the gaskets 6a and 6c as shown in FIG. 1D; the water vapor seal member 3 is formed from the end of the electrolyte membrane 2 to the center of the membrane as shown in FIG. When formed between the gaskets 6a and 6c toward the portion; as shown in FIG. 1E, the water vapor seal member 3 is joined from the end of the electrolyte membrane 2 to the joint surface 9a between the gaskets 6a and 6c and the gas diffusion layers 5a and 5c. 9c; and as shown in FIG. 1F, the steam seal member 3 is electrically connected so as to straddle the joint surfaces 9a, 9c between the gaskets 6a, 6c and the gas diffusion layers 5a, 5c. It encompasses cases such as when formed in Shitsumaku 2. 1E and 1F show an aspect in which the joining surfaces 9a and 9c of the anode-side and cathode-side gaskets 6a and 6c and the gas diffusion layers 5a and 5c are in the same position with respect to the thickness direction of the MEA 1. However, when these joining surfaces 9a and 9c are different from each other in the thickness direction of the MEA 1, they may be formed so as to straddle at least one of the joining surfaces 9a and 9c. It is preferable that the water vapor seal member 3 is formed so as to include the joint surface 9c between the layer 5c and the gasket 6c. This is because water is formed particularly on the cathode side. 1B to 1F show an example in which the end of the electrolyte membrane 2 and the end of the water vapor seal member 3 are closely bonded (including an example in which the water vapor seal member 3 is formed in the electrolyte membrane 2). However, as shown in FIG. 1G, there may be a gap 10 between the end of the electrolyte membrane 2 and the end of the water vapor seal member 3. That is, the water vapor seal member 3 may be formed separately from the electrolyte membrane 2. Even in such a case, the gas leakage (gas leak) in the vertical (surface) direction of the electrolyte membrane 2 and the gas leakage (gas leak) in the side surfaces of the catalyst layers 4a and 4c and the side surface of the electrolyte membrane 2 are as follows. This is because gas impermeable gaskets 6a and 6c and seals (water vapor seal member 3, adhesive layers 7a and 7c) can be suppressed and prevented.

  Among the above examples, the water vapor sealing member 3 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 suppress and prevent the permeation of water vapor from the side surface portion of the electrolyte membrane 2 and maintain the humidity of the electrolyte membrane 2 well. In addition, such a structure is, for example, as shown in FIGS. 1C and 1F, as compared with the case where the water vapor seal member 3 is formed in the middle of the lateral outer periphery of the electrolyte membrane 2 between the gaskets 6a and 6c. The formation process of the water vapor seal member 3 can be performed more easily. In the present specification, the “outermost peripheral portion of the electrolyte membrane” means a portion of the electrolyte membrane that is in contact with the gaskets 6a to 6c on the anode catalyst layer 4a side and / or the cathode catalyst layer 4c side, which is farthest from the catalyst layer. 1B, 1D, and 1E, the case where the water vapor seal member 3 is formed so as to include the end portion of the electrolyte membrane 2 is included.

  The seal is composed of the water vapor seal member 3 and the adhesive layers 7a and 7c, and the water vapor seal member 3 is at least in the thickness direction of the electrolyte membrane-electrode assembly 1 at least in the gasket 6a. , 6c is preferably disposed at a position corresponding to the portion where the reaction force is applied. Here, the “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 1. For example, a solid polymer fuel cell has a structure in which an electrolyte membrane-electrode assembly is sandwiched between separators as described in the above section of the prior art, and is disposed in each catalyst layer via a gas diffusion layer. Fuel gas and oxidant gas are supplied from the separator, but when the MEA is sandwiched between the separators so that the gas flows independently and does not leak to the outside, the sealing protrusion (lip) is placed on the gasket. Be placed. For this reason, a compression pressure is applied to the arrangement site of the projecting portion for sealing when the MEA is sandwiched by the separator. Here, if there is an electrolyte membrane at the location where the convex portion for sealing is located, the membrane is thin and low in strength, so the membrane collapses due to compressive stress and the anode catalyst layer and cathode catalyst layer come into contact with each other and short circuit May occur. In contrast, in the thickness direction of the electrolyte membrane-electrode assembly 1, the water vapor seal member 3 formed of an adhesive or a material having a high compression elastic modulus is applied to the gaskets 6 a and 6 c as described in detail below. Therefore, the electrolyte membrane is not crushed by compressive stress even when / after the MEA is held by the separator. In such a case, for example, in the case of a polymer electrolyte fuel cell, the arrangement position of the water vapor seal member 3 is at least part of the convex portion for sealing in the thickness direction of the electrolyte membrane-electrode assembly 1. There is no particular limitation as long as the position includes the position.

  2A to 2B are schematic cross-sectional views illustrating exemplary embodiments of the positional relationship between the water vapor sealing member and the sealing convex portion (lip) in the MEA of the present invention.

  As shown in FIG. 2A, the positional relationship between the water vapor seal member 3 and the sealing convex portions (lips) 8a and 8c is such that, in the thickness direction of the electrolyte membrane-electrode assembly 1, the sealing convex portions 8a, It is preferable that the water vapor sealing member 3 is disposed so as to completely include 8c. The positional relationship here refers to the relationship between the region (position) where the projections 8a and 8c for sealing are projected on the electrolyte membrane portion (arrow portion in FIG. 1A) and the position of the water vapor seal member 3 in the electrolyte membrane portion. (Hereinafter the same shall apply). When the anode-side sealing convex portion 8a and the cathode-side sealing convex portion 8c are arranged at different positions, as shown in FIG. 2B, both the sealing convex portions 8a. , 8c is preferably arranged so that the water vapor seal member 3 is completely included.

  2A and 2B, the cross-sectional shape of the sealing projections 8a and 8c is a triangle. This shape is particularly suitable if the sealing property of the electrolyte membrane-electrode assembly 1 can be improved. The shape of the cross section is not limited, and may be a polygon having a triangular shape or more (for example, a quadrilateral such as a square quadrilateral, a rectangle, a pentagon, a hexagon, etc.), a cylinder, a truncated cone, a polygonal column, and a polygonal frustum. Moreover, the site | part in which the convex parts 8a and 8c for a seal | sticker are formed will not be restrict | limited especially if the sealing performance of the electrolyte membrane-electrode assembly 1 can be improved, and with at least one part of gasket 6a, 6c. What is necessary is just to form in contact. Further, sealing convex portions 8a and 8c may be dotted so as to fill the concave portion of the separator formed by a flow path such as a gas or a cooling medium, and the electrode (catalyst layer) on the electrolyte membrane 2 may be dotted. The convex portions 8a and 8c for sealing may be formed in a frame shape so as to surround the peripheral portion. In addition, the gaskets 6a, 6c are formed so that the sealing protrusions 8a, 8c formed on the gaskets 6a, 6c are fitted between the sealing protrusions (not shown) formed also on the separator. The convex portions 8a and 8c for sealing may be formed on 6c, and the convex portions (seal members) 8a and 8c for sealing may take an independent form in an O-ring shape.

  The material of the projecting portions 8a and 8c for sealing is not particularly limited as long as the material can ensure the sealing property between the separator and the electrolyte membrane-electrode assembly 1, but for example, fluorine rubber, silicon rubber, ethylene propylene rubber (EPDM), rubber materials such as polyisobutylene rubber, fluorine-based materials such as polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), polyhexafluoropropylene, and tetrafluoroethylene-hexafluoropropylene copolymer (FEP) Preferred examples include polymer materials 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.

  In the present invention, as shown in FIGS. 1B to 1G and FIGS. 2A and 2B, the water vapor seal member 3 may be formed at least one part between the gaskets 6a and 6b. It is preferable that the gas (especially water vapor) sealability is kept as high as possible. Therefore, it is preferable that the water vapor seal member 3 is formed in the lateral outer peripheral portion of the electrolyte membrane 2 so as not to be interrupted in the middle as in one stroke. At this time, the shape of the water vapor seal member 3 is not particularly limited as long as it is formed so as not to be interrupted.

  3A to 3C are schematic plan views illustrating exemplary embodiments of the positional relationship in which the electrolyte membrane and the water vapor seal member are formed in the MEA of the present invention.

  The positional relationship in which the electrolyte membrane 2 and the water vapor seal member 3 are formed is, for example, concentric with the electrolyte membrane 2 as shown in FIG. 3A (corresponding to the case of FIG. 1B) and FIG. 3B (corresponding to the case of FIG. 1C). It may be arranged in a shape. Alternatively, as shown in FIG. 3C, the outer peripheral portion of the side of the electrolyte membrane 2 may be arranged so as to make a round with an indefinite shape. Considering the ease of forming the water vapor seal member 3 and the like, it is preferable that the water vapor seal member 3 is disposed concentrically with respect to the electrolyte membrane 2. 3A to 3C show the case where the electrolyte membrane 2 is rectangular, the electrolyte membrane 2 according to the present invention is not limited to the above shape, and may be any shape. Also, the width of the water vapor seal member 3 need not be constant, and can be selected as appropriate, for example, by increasing the width of a portion where water vapor permeates easily. Considering the ease of formation and the like, the width of the water vapor seal member 3 is preferably constant. Moreover, as shown in FIGS. 1B to 1G (further, see FIGS. 2A and B, FIGS. 3A to C, FIGS. 4, 5A to D, and FIGS. 6A and B), the size of the water vapor seal member 3 varies. Various sizes can be applied and are not particularly limited. However, the thickness of the water vapor seal member 3 is preferably equal to the thickness of the electrolyte membrane 2 used. This is because the permeation of water vapor from the electrolyte membrane 2 can be completely prevented.

  In the present invention, the water vapor seal member 3 may be formed of any material. However, in consideration of water vapor permeability and resistance to compressive stress, the water vapor seal member 3 is formed of an adhesive or has a compressive elastic modulus higher than that of the electrolyte membrane 2. It is preferable to be formed of a material having a high value. The method for forming the water vapor seal member 3 in the former case is not particularly limited. For example, a method of impregnating an adhesive in a predetermined position of the electrolyte membrane 2 (for example, a lateral outer peripheral portion of the electrolyte membrane 2) (FIGS. 1B to 1B) 1F, etc.), a method of arranging an adhesive member at a predetermined position between the gaskets 6a, 6c on the outer periphery of the electrolyte membrane 2 or the side of the electrolyte membrane 2 (see FIG. 1G, etc.) and the like. By using such a method, the water vapor seal member 3 can be formed easily and simply, and the above method can accurately control the formation position of the water vapor seal member 3. The adhesive that can be used in this case is not particularly limited as long as it does not transmit water vapor. However, hot-melt adhesives such as polyolefin, polypropylene, and thermoplastic elastomers, olefin adhesives such as acrylic adhesives, polyesters, and polyolefins. Agents can be used. Of these, hot melt adhesives are preferably used in consideration of ease of bonding, accurate bonding position, and long-time bonding force. The melting temperature of the hot-melt adhesive when using the hot-melt adhesive is easy to handle (easiness of impregnation into the electrolyte membrane, easy to form an adhesive member), deterioration temperature of the electrolyte membrane, fuel cell In view of durability at the use temperature, the temperature is preferably 25 to 150 ° C, more preferably 70 to 120 ° C.

  A specific method in the case where the water vapor seal member 3 is formed by impregnating an adhesive in a predetermined position of the electrolyte membrane 2 (for example, a lateral outer peripheral portion of the electrolyte membrane 2) (see FIGS. 1B to 1F) There is no particular limitation. For example, a method of immersing a predetermined part of the electrolyte membrane 2 in a hot melt adhesive previously melted at 100 to 180 ° C .; a hot melt adhesive melted in the same manner as described above is used as an electrolyte A method such as application to a predetermined portion of the film 2 by a known method such as a screen printing method, a deposition method, or a spray method can be used.

  Further, the gasket at a predetermined position between the gaskets 6a and 6c on the electrolyte membrane 2 or the side outer peripheral portion of the electrolyte membrane 2, for example, the gasket on the outer side (side outer peripheral portion) outside the end (outermost peripheral portion) of the electrolyte membrane. When the water vapor seal member 3 is formed by disposing an adhesive member between 6a and 6c at a position in close contact with the end of the electrolyte membrane 2 or at a position away from the end of the electrolyte membrane 2 (see FIG. 1G). A specific method is not particularly limited. For example, a hot melt adhesive previously melted at 100 to 180 ° C. is applied to a transfer sheet to a predetermined thickness and cured to form an adhesive member (water vapor seal member 3) separately from the electrolyte membrane 2, This is adhered to the end of the electrolyte membrane 2 or separated so that a gap 10 is formed; a gas diffusion layer 5 and a gasket 6 are formed on the transfer mount separately from the anode and the cathode, Further, the catalyst layer 4 is formed on the gas diffusion layer 5 and the adhesive layer (adhesive portion) 7 is sequentially formed on the gasket 6 to form a laminate, and then either the anode laminate or the cathode laminate is formed. A method of forming the water vapor seal member 3 by placing the electrolyte membrane 2 at a predetermined position, applying an adhesive melted at the same temperature as described above, and arranging the adhesive member at the remaining position can be used. So After, by attaching the other of the laminate can be formed MEA1 having a gas diffusion layer 5.). When the adhesive used for the adhesive layers (adhesive portions) 7a, 7c and the adhesive member (water vapor seal member 3) is the same, the gas diffusion layer 5 and the gasket 6 are formed on the transfer mount, Further, the catalyst layer 4 is formed on the gas diffusion layer 5, the adhesive layer (adhesive portion) 7 and the adhesive member (water vapor seal member 3) are simultaneously formed on the gasket 6, and the electrolyte membrane 2 is then applied to the remaining portion. May be. The adhesive layers (adhesive portions) 7a and 7c have the same thickness as the catalyst layers 4a and 4c as shown in FIGS. 1B to 1G (= the outer peripheral portions in the surface direction of the anode catalyst layer 4a and the cathode catalyst layer 4b; In other words, it may be disposed on the same surface as the catalyst layers 4a and 4c) and may be thicker than the catalyst layers 4a and 4c. "..."

  Or as above-mentioned, the water vapor | steam sealing member 3 may be comprised with the material whose compression elastic modulus is higher than the electrolyte membrane 2. FIG. The water vapor seal member 3 formed of a material having a higher compressive modulus than the electrolyte membrane 2 (that is, not easily crushed) is applied to a portion where the reaction force is applied to the gaskets 6a and 6c in the thickness direction of the electrolyte membrane-electrode assembly. If it arrange | positions, since the electrolyte membrane 2 is not crushed at the time of / after the MEA sandwiched by the separator or at the time of joining / after each layer of the MEA, a short circuit can be prevented, which is preferable.

  The material having a high compressive elastic modulus that can be used at this time is not particularly limited, does not transmit water vapor, and can resist the reaction force applied to the gaskets 6a and 6c at the time of sandwiching or joining with a general separator. As such, the material is not particularly limited as long as it is a material that is more difficult to sag than the electrolyte membrane 2. 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 gaskets 6a and 6c. This is advantageous in that it is not necessary to prepare many kinds of materials and is economically advantageous, and in addition, it is not necessary to select an adhesive. That is, as shown in FIGS. 1B to 1G, the MEA 1 of the present invention is formed with the gaskets 6a and 6c and the water vapor seal member 3 through one adhesive layer (adhesive portion) 7a and 7c. If the material of the water vapor seal member 3 is the same, an equivalent adhesive force is exhibited with the same adhesive. Therefore, the layers constituting the MEA are closely bonded with one adhesive, and an MEA with high adhesion can be obtained.

  When the water vapor seal member 3 is formed of the same material as that constituting the gaskets 6a and 6c, the water vapor seal member 3 and the gasket 6 are integrally formed as shown in FIG. May be. In other words, the gasket 6a or 6c on either the anode / cathode side and the water vapor seal member 3 may be integrated. FIG. 4 shows an example in which the anode-side gasket 6 a and the water vapor seal member 3, which are separated by a virtual line k in the figure, are integrally formed (integrated). In the figure, the integrally formed one is denoted as 3 / 6a. Even when the water vapor seal member 3 and the gasket 6a are integrally formed (integrated), the function of preventing gas leakage (gas leakage) from the side surface of the electrolyte membrane 2 can be exhibited. Also regarding the configuration formed in a general manner, it belongs to the technical scope (scope of rights) of the present invention. Similarly, the cathode side gasket 6c and the water vapor sealing member 3 that are integrally formed belong to the technical scope (right range) of the present invention. Gas leakage (gas leakage) from the side surfaces of the catalyst layers 4a and 4c can be prevented by adhesive layers (adhesive portions) 7a and 7c as shown in FIG.

  Further, by integrally forming the water vapor seal member 3 and the gasket 6a or 6c on either the anode / cathode side, the number of parts and the number of manufacturing steps can be reduced. That is, it is possible to provide the MEA 1 having an edge seal with a simple structure with few parts and improved durability. Specifically, there are fewer parts than the provision of the water vapor seal member 3 and the gasket 6a or 6c separately (for example, the number of parts such as the water vapor seal member 3 and the adhesive layers (adhesive portions) 7a and 7c, reduction in the amount of use, expensive film) It is possible to provide an MEA having an edge seal (gas impermeability) that is inexpensive and has a simple structure with a reduced area. In addition to providing MEA with excellent durability (prevention of catalyst corrosion, suppression of electrolyte membrane decomposition, and prevention of creep), alignment of the water vapor seal member 3 and the gasket 6a or 6c can be performed. The assembly process becomes easy, such as being unnecessary. Further, by forming them integrally, there is no adhesive portion at the phantom line k in the figure, so that the mechanical strength can be improved.

  Alternatively, the water vapor sealing member 3 according to the present invention (part disposed so as to prevent gas leakage from the side surface of the electrolyte membrane 2 that is a part of the seal) 3 prevents gas leakage from the side surface of the electrolyte membrane 2. In addition to the function to perform, it may be a reinforcing member (hereinafter simply referred to as “reinforcing member”) having higher strength than the electrolyte membrane 2 so as to have a reinforcing function. At this time, the reinforcing member 3 includes gas diffusion layers 5a and 5c and gaskets 6a and 6c further formed on the anode catalyst layer 4a and / or the cathode catalyst layer 4c with respect to the thickness direction of the electrolyte membrane-electrode assembly 1. It is desirable that it is disposed on at least a part of the lateral outer periphery of the electrolyte membrane 2 so as to include the joint surfaces 9a and 9c.

  More preferably, the reinforcing member 3 includes the joining surfaces 9a and 9c of the gas diffusion layers 5a and 5c on both sides of the anode catalyst layer 4a and the cathode catalyst layer 4c and the gaskets 6a and 6c. It is arrange | positioned in at least one part of a side outer peripheral part. Specifically, with respect to the thickness direction of the electrolyte membrane-electrode assembly 1, a first gas diffusion layer 5a further formed on the anode catalyst layer 4a and a first gas diffusion layer further formed on the cathode catalyst layer 4c. And a two-gas diffusion layer 5c, wherein the seal prevents leakage of gas from the side surface of the electrolyte membrane 2 and has a strength higher than that of the electrolyte membrane 2 (preferably suitable for the water vapor seal member). 3) and adhesive layers 7a and 7c for bonding the reinforcing member 3 or the electrolyte membrane 2 and the gaskets 6a and 6c, and the reinforcing member 3 includes the first gas diffusion layer 5a. And the anode side gasket 6a or the junction surface 9c between the second gas diffusion layer 5c and the cathode side gasket 6c. It is intended.

  FIGS. 5A to 5B show typical embodiments in the case where the reinforcing member is used as a water vapor sealing member (portion arranged to prevent leakage of gas from the side surface of the electrolyte membrane which is a part of the seal). It is the cross-sectional schematic of MEA of this invention showing this. In order to distinguish the reinforcing member 3 from other water vapor sealing members, the cross section of the other water vapor sealing member 3 is indicated by hatching representing a resin material (FIGS. 1B to 1G, FIG. 2A to FIG. 2). 2B, the cross section of the reinforcing member 3 is indicated by hatching (refer to reference numeral 3 in FIGS. 5A to 5D and FIGS. 6A to 6B). See hatching).

  Due to the presence of the reinforcing member 3, the collapse of the membrane after holding / after the MEA by the separator and hot pressing / after each constituent layer of the MEA is suppressed in the same manner as described for the material having a higher compression modulus than that of the electrolyte membrane 2.・ Prevents the occurrence of short circuit. Further, stress is particularly concentrated on the joint surfaces 9a and 9c between the first and second gas diffusion layers 5a and 5c and the gaskets 6a and 6c during the sandwiching of the MEA by the separator and the hot pressing of each constituent layer of the MEA. For this reason, as shown in FIG. 5A, the water vapor seal member 3 constituted by the reinforcing member 3 is bonded to the first and second gas diffusion layers 5a, 5c and gaskets 6a, 6c where stress is concentrated, By disposing so as to include 9c, the collapse of the electrolyte membrane 2 can be effectively suppressed / prevented. In the present invention, as shown in FIG. 5B, the joint surface 9c between the second gas diffusion layer 5c and the gasket 6c on the cathode side and the joint surface between the first gas diffusion layer 5a and the gasket 6a on the anode side. The position of 9a is preferably different. During sandwiching of the MEA by the separator and hot pressing of each constituent layer of the MEA, stress applied to the joint surfaces 9a and 9c of the gas diffusion layers 5a and 5c and the gaskets 6a and 6c is dispersed, and the electrolyte membrane 2 is more ruptured. This is because it can be effectively suppressed and prevented. In such a case, as shown in FIG. 5B, it is preferable that the water vapor seal member constituted by the reinforcing member 3 is disposed so as to completely include both the joint surfaces 9a and 9c.

  In the present invention, the material constituting the reinforcing member 3 is not particularly limited, and a material having higher strength than the electrolyte membrane 2 can be appropriately used. For example, the reinforcing member 3 may be made of a material different from the constituent material of the polymer electrolyte membrane 2. Examples of such a material include polytetrafluoroethylene (PTFE), polyvinylidene fluoride ( PVDF) and Kapton. Among these, Kapton 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. Alternatively, the reinforcing member 3 may include a polymer electrolyte similar to the electrolyte membrane 2 described in detail above. For example, the reinforcing member 3 may be manufactured by filling a porous body with an electrolyte. The form of the porous body that can be used in this case is not particularly limited, and can be appropriately selected from conventionally known polymer materials such as polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), polyimide, polyolefin, polysulfone and the like. Among these, fluorine-based polymer materials such as polytetrafluoroethylene (PTFE) and polyvinylidene fluoride (PVDF) are preferably used, and in particular from the viewpoint of chemical resistance and quality stability, it is made of polytetrafluoroethylene (PTFE). A porous body is more preferably used. The porosity of the porous body constituting the reinforcing member 3 is not particularly limited and may be appropriately set in consideration of ease of manufacture, desired strength, etc., but is preferably 20 to 80%.

  FIG. 5C shows a typical embodiment when a reinforcing member having adhesive ability is used as the seal (the water vapor seal member 3 and the adhesive layers (adhesive portions) 7a and 7c are integrally formed). It is the cross-sectional schematic of MEA of this invention which was made.

The reinforcing member may be formed of a material having adhesive ability, particularly heat fusion ability. When a reinforcing member formed of such a material is used as the water vapor seal member 3 or the entire seal (see reference numeral 3 / 7a / 7c in FIG. 5C), particularly when the MEA 1 is assembled by a transfer method, a hot press is used. Since the reinforcing member sometimes exhibits adhesive ability, the adhesion between the reinforcing member and the electrolyte membrane 2, the catalyst layers 4a and 4c, and the gaskets 6a and 6c can be further improved. Such a reinforcing member is preferably such that the reinforcing member exhibits adhesive ability at the time of hot pressing. For example, the reinforcing member preferably exhibits adhesive ability at 100 to 200 ° C. Such a reinforcing member is not particularly limited, and specifically, a desired shape such as a sheet knitted by combining fibers made of a low melting point resin such as an olefin resin can be used. . More specifically, as the reinforcing member, low melting point resin fibers such as polypropylene (PP) fibers, polyethylene (PE) fibers, and modified olefin fibers, polytetrafluoroethylene (PTFE) fibers, glass fibers (GF), etc. And other fibers, and polytetrafluoroethylene (PTFE) fibers, glass fibers (GF), and polypropylene (PP) fibers are appropriately used (for example, PTFE: GF: PP = 20: 30: 50). (Mass ratio)) Particularly preferred are those knitted in combination, knitted by appropriately combining glass fibers (GF) and polypropylene (PP) fibers (for example, GF: PP = 50: 50 (mass ratio)), and the like. Can be used. In such a case, the seal formed by the reinforcing member (the water vapor seal member 3 and the adhesive layers (adhesive portions) 7a and 7c are integrally formed) is directly connected as shown in FIG. 5C. The gaskets 6a and 6c may be joined. Even in such a case, a seal (a steam seal member 3 and adhesive layers (adhesive portions) 7a and 7c are integrally formed) and gaskets 6a and 6c that are sufficiently formed by a hot press to form a reinforcing member. Furthermore, the electrolyte membrane 2 and the catalyst layers 4a and 4c can be joined. A seal (entire) formed by integrally forming the water vapor seal member 3 and the adhesive layers (adhesive portions) 7a and 7c, which is divided by virtual lines k ₁ and k ₂ in the figure, is denoted by reference numeral 3 / 7a / 7c. write.

  In the present invention, the role of the function of preventing gas leakage (gas leakage or gas leakage), in particular, the function of preventing gas leakage from the side surfaces of the anode catalyst layer 4a and the cathode catalyst layer 4c and the side surfaces of the electrolyte membrane 2, It is effectively expressed by the combination of both the seal and gasket components. Therefore, (i) These structural members may be a structure (composite body) in which a part or all (the whole) of each structural member is integrally formed. For example, as shown in FIG. 4, a structure (reference numeral 3 / 6a) in which a water vapor seal member 3 as a part of the seal and a gasket 6a on the anode side are integrally formed can be exemplified, but the structure is not limited to these. It is not a thing. For example, a structure in which an anode side adhesive layer (adhesive part) 7a and an anode side or cathode side gasket 6a or 6c are integrally formed, the entire seal (reference numeral 3 / 7a / 7b; FIG. 5C) and an anode- or cathode-side gasket 6a or 6c integrally formed, the entire seal (reference numeral 3 / 7a / 7b; see FIG. 5C) and the entire anode- and cathode-side gasket (6a). And 6c) can be exemplified. (Ii) Alternatively, each of these constituent members may be a structure (aggregate) composed of a plurality of members (parts). For example, in the seal, three members (parts) of the water vapor seal member 3, the anode-side adhesive layer (adhesive portion) 7a, and the cathode-side adhesive layer (adhesive portion) 7c are joined (adhered) to prevent gas leakage. Although the structure formed by thru | or close_contact | adherence can be illustrated, it does not restrict | limit at all to these. For example, as the water vapor seal member 3, a laminate in which a plurality of water vapor seal members having different physical properties are laminated and bonded in the thickness direction, or as the water vapor seal member 3, a plurality of water vapor seal members having different physical properties are bonded in the surface direction. The connection body etc. can be illustrated. In the gasket, there is exemplified a structure in which two members (parts) of the anode side gasket 6a and the cathode side gasket 6c are arranged so as to prevent gas leakage through the electrolyte membrane 2 or the water vapor seal member 3 of the seal. Yes, but you are not limited to these. For example, a laminate in which a plurality of gasket members having different physical properties are laminated in the thickness direction and bonded to the gasket 6a or 6c on the anode side or the cathode side, or a plurality of gaskets 6a or 6c on the anode side or cathode side having a plurality of physical properties different from each other. Examples include a joined body in which gasket members are bonded in the surface direction. (Iii) or a structure (composite) in which these individual components are integrated. For example, in the seal, a structure (reference numeral 3/3) in which three members (parts) of the water vapor seal member 3, the anode-side adhesive layer 7a, and the cathode-side adhesive layer 7c are formed so as to prevent gas leakage. 7a / 7b; see FIG. 5C), but is not limited thereto. For example, a structure in which the water vapor seal member 3 and two members (parts) of the anode side or cathode side adhesive layer (adhesive portion) 7a or 7c are integrally formed so as to prevent gas leakage can be exemplified. (Iv) Or, a function of a function layer for preventing gas leakage (gas leakage or gas leakage), in particular, a function of preventing gas leakage from the side surfaces of the anode catalyst layers and the cathode catalyst layers 4a and 4c and the side surfaces of the electrolyte membrane 2. As long as it can express the above, the above embodiments (i) to (iii) may be appropriately combined.

  Moreover, FIG. 5D is sectional drawing of MEA of this invention in case it has the reinforcement member 3 as a water vapor | steam sealing member, and a reinforcement layer.

  In the present invention, as shown in FIG. 5D, the reinforcing layer 3 ′ having a higher strength than the electrolyte membrane 2 has an anode catalyst layer 4 a and / or a cathode catalyst layer in the thickness direction of the electrolyte membrane-electrode assembly 1. It is preferable to be disposed at an intermediate portion of the electrolyte membrane 2 so as to overlap at least a part of 4c. Thereby, the strength of the electrolyte membrane 2 itself can also be improved.

  The material constituting the reinforcing layer 3 ′ that can be used in this case 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. As the porous body and the electrolyte, the same materials as described in the reinforcing member can be used. The thickness of the reinforcing layer 3 ′ varies depending on the thickness and type of the electrolyte membrane 2 and the desired strength, and is not particularly limited, but is preferably about 10 to 50% of the thickness of the electrolyte membrane 2. Further, the position of the reinforcing layer 3 ′ is not particularly limited. However, in consideration of the strength of the electrolyte membrane 2 and the like, it is preferable that the reinforcing layer 3 ′ is located at a substantially central portion in the thickness direction of the electrolyte membrane 2 as shown in FIG. 5D. In FIG. 5D, the reinforcing layer 3 ′ has a form in which the reinforcing member 3 as the water vapor sealing member and the ends are joined to each other, but is not limited to such a form. For example, even if there is a gap between the end of the reinforcing member 3 as a water vapor seal member and the end of the reinforcing layer 3 ′, or the reinforcing layer 3 ′ is intermittently disposed in the center of the electrolyte membrane 2. Alternatively, any arrangement may be employed, such as arrangement only at the center in the surface direction of the electrolyte membrane 2. Considering the strength improvement of the electrolyte membrane 2, the reinforcing layer 3 ′ is disposed at the center of the entire electrolyte membrane 2 so as to be joined to the end of the reinforcing member 3 as a water vapor seal member, as shown in FIG. 5D. It is particularly preferable. In the above description, the reinforcing layer 3 ′ has been used in combination with the reinforcing member 3 as a water vapor seal member. However, in the present invention, the same applies to the combination with the other water vapor seal portion 3 described above. Can be applied.

  1-4 and FIG. 5A, the joining surface 9a of the gasket 6a on the anode side and the first gas diffusion layer 5a, and the joining surface 9c of the gasket 6c on the cathode side and the second gas diffusion layer 5c are the thickness of the MEA 1. Although arranged at the same position with respect to the direction, these joint surfaces 9a and 9c may be arranged at different positions as shown in FIGS. As described above, when the joining surfaces 9a and 9c are arranged at different positions with respect to the thickness direction of the MEA 1, the gas diffusion layer and the MEA are sandwiched between / after and when the MEA constituent layers are hot-pressed / after. The compressive stress applied to the joint surfaces 9a and 9c with the gasket can be dispersed to reduce the stress concentration. For this reason, the fracture | rupture by the stress of an electrolyte membrane can be suppressed and prevented more effectively, and it is preferable. When the bonding surfaces 9a and 9c are arranged at different positions with respect to the thickness direction of the MEA 1, the bonding surfaces 9a and 9c are arranged so that the area of the anode catalyst layer 4a is larger than the area of the cathode catalyst layer 4c. Preferably they are arranged. 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, a portion where the difference between the cathode potential and the electrolyte potential is large can be significantly reduced. This is because corrosion of the conductive carrier) can be effectively prevented / suppressed. In such a case, there is little or no peripheral portion where only the cathode catalyst layer 4c exists, and little or no oxygen cross-leak from the cathode to the anode at the end of the cathode catalyst layer 4c occurs. Therefore, it is possible to effectively prevent / suppress deterioration of the electrolyte membrane 2 which has been a serious problem in the past. Therefore, the fuel cell using the MEA having such a structure can maintain the performance during start / stop / continuous operation and OCV for a long period of time, and the fuel consumption can be improved.

  6A to 6B are cross-sectional schematic views of the MEA of the present invention showing a typical embodiment in the case where the adhesive layer (adhesive portion) is formed inside the electrolyte membrane beyond the gasket.

  1-4 and FIG. 5A, the anode-side adhesive layer (adhesive portion) 7a and the cathode-side adhesive layer (adhesive portion) 7c are respectively in the thickness direction of the gasket 6a, the gasket 6c, and the MEA 1. However, as shown in FIGS. 6A and 6B, the end points of the adhesive layers (adhesive portions) 7a and 7c and the gaskets 6a and 6c may be arranged at different positions. Even in such a case, as described above, as shown in FIGS. 6A and 6B, the adhesive layers (adhesive portions) 7a and 7c are formed so that the area of the anode catalyst layer 4a is larger than the area of the cathode catalyst layer 4c. Is preferably arranged. When the end portions of the adhesive layers (adhesive portions) 7a and 7c end at different positions from the end portions 1 of the gaskets 6a and 6c and the thickness direction of the MEA, as shown in FIG. 6A, the adhesive layers (Adhesive portions) 7a and 7c may be formed so as to be under the gas diffusion layers 5a and 5c beyond the joint surfaces 9a and 9c between the gas diffusion layers 5a and 5c and the gaskets 6a and 6c, respectively. preferable. In such a case, the adhesive layer (adhesive portion) 7c is in contact with all of the gas diffusion layer 5c, the gasket 6c, the water vapor seal member 3, and the electrolyte membrane 2, and the adhesive layer (adhesive portion) 7a is the gas diffusion layer. Since it is in contact with 5a, gasket 6a, and water vapor seal member 3, each constituent member of MEA can be united with higher joining nature, and is preferred. 6A and 6B has been described (illustrated) by taking the example of the reinforcing member 3 as a water vapor seal member, it can be similarly applied to other water vapor seal members 3. Further, when the adhesive layers (adhesive portions) 7a and 7c are formed beyond the bonding surfaces 9a and 9c and under the gas diffusion layers 5a and 5c, as shown in FIG. 6B, the gasket 6a and the gas diffusion layer are formed. There may be a gap 11 between 5a and / or between the gasket 6c and the gas diffusion layer 5c. Even in such a case, gas permeation / leakage can be sufficiently suppressed / prevented by the seal (water vapor seal member 3 and adhesive layers (adhesive portions) 7a, 7c) and gaskets 6a, 6c. Although the above description has been made only on the cathode side, the same application can be made only on the anode side or on both the cathode and anode sides.

  The electrolyte membrane-electrode assembly 1 of the present invention can be produced in the same manner as a known method or by using an appropriately modified method. Specifically, for example, catalyst layers 4a and 4c, adhesive layers (adhesive portions) 7a and 7c that are the remainder of the seal, gaskets 6a and 6c on both surfaces of the electrolyte membrane 2 and the water vapor seal member 3 that is a part of the seal. A method of sequentially forming 6c and gas diffusion layers 5a and 5c in an appropriate arrangement can be used.

  Hereinafter, a preferred method for producing the electrolyte membrane-electrode assembly 1 according to the present invention by a transfer method will be described in detail. That is, (i) for the anode side and the cathode side, the catalyst ink is applied on the transfer mount to form the catalyst layers 4a and 4c, respectively, and the lateral outer peripheral portions thereof are sealed with the water vapor seal member 3. After sandwiching the electrolyte membrane 2, hot pressing is performed, and then the transfer mount is removed to obtain a laminate of the anode catalyst layer 4 a and the electrolyte membrane 2 -cathode catalyst layer 4 c sealed with the water vapor seal member 3. After the gas diffusion layers 5a and 5c are arranged on the catalyst layers 4a and 4c, the adhesive layers (adhesive portions) 7a and 7c and the gasket 6a are placed at predetermined positions on the electrolyte membrane 2 sealed with the water vapor seal member 3, respectively. 6c, respectively, to obtain MEA 1 of the present invention; (ii) catalyst ink is applied on the gas diffusion layers 5a and 5c for the anode side and the cathode side, respectively. After forming the catalyst layers 4a and 4c and sandwiching the electrolyte membrane 2 whose side outer peripheral portions are sealed with the water vapor sealing member 3, hot pressing is performed to form the gas diffusion layers 5a and 5c and the catalyst layers 4a and 4c. Then, after obtaining a laminate of the electrolyte membrane 2 sealed with the water vapor seal member 3, adhesive layers (adhesive portions) 7a and 7c and a gasket 6a are formed at predetermined positions on the electrolyte membrane 2 sealed with the water vapor seal member 3. 6c, respectively, to obtain the MEA 1 of the present invention; (iii) After forming the gas diffusion layers 5a and 5c and the gaskets 6a and 6c on the transfer mount, the catalyst ink is formed on the gas diffusion layers 5a and 5c. Is applied to form catalyst layers 4a and 4c and adhesive layers (adhesive portions) 7a and 7c are formed on the gaskets 6a and 6c to obtain a laminate. The anode laminate thus obtained and Caso A method for obtaining MEA 1 of the present invention by sandwiching the electrolyte membrane 2 having two side laminates sealed with the water vapor sealing member 3 and then performing hot pressing, and then peeling off the transfer mount. (Iv) After forming the gas diffusion layers 5a and 5c on the transfer mount, the catalyst ink is applied onto the gas diffusion layers 5a and 5c to form the catalyst layers 4a and 4c, and then the transfer mount Gaskets 6a and 6c and adhesive layers (adhesive portions) 7a and 7c are sequentially formed on the remaining portions to obtain a laminate, and two anode laminates and two cathode laminates thus obtained are used. A method of obtaining MEA 1 of the present invention by performing hot pressing after sandwiching the electrolyte membrane 2 whose outer periphery is sealed with the water vapor sealing member 3, and then peeling off the transfer mount; (v) on the transfer mount Gasket 6a, 6c and adhesion After sequentially forming the layers (adhesive portions) 7a and 7c, the gas diffusion layers 5a and 5c are formed on the remaining portions of the transfer mount, and a catalyst ink is applied on the gas diffusion layers 5a and 5c. Then, the catalyst layers 4a and 4c are formed to obtain a laminate, and the electrolyte membrane in which the lateral outer peripheral portion is sealed with the water vapor seal member 3 in the two laminates for anode and cathode thus obtained. A method of obtaining MEA 1 of the present invention by performing hot pressing after sandwiching 2 and then peeling off the transfer mount can be used.

  Hereinafter, the method (i) will be described in detail. That is, in the above method (i), (a) for the anode side and the cathode side, the catalyst ink is applied on the transfer mount to form the catalyst layers 4a and 4c, respectively. A sheet was obtained, and after sandwiching the electrolyte membrane 2 whose side outer peripheral portion was sealed with the water vapor sealing member 3 between the anode and cathode transfer sheets formed in (a) and (a), hot pressing was performed, and thereafter Then, a laminate of the anode catalyst layer 4a and the electrolyte membrane 2-cathode catalyst layer 4c sealed with the water vapor seal member 3 is obtained by peeling off the transfer mount, and (c) a gas diffusion layer on each of the catalyst layers 4a and 4c. (GDL) 5a, 5c are arranged, and after obtaining a laminate of the electrolyte membrane 2 sealed with the gas diffusion layers 5a, 5c, the catalyst layers 4a, 4c and the water vapor seal member 3, (D) the water vapor seal member In a predetermined position of the sealed on the electrolyte membrane 2, and the adhesive layer (adhesive portion) 7a, 7c and gaskets 6a, 6c were respectively formed, obtain MEA1 of the present invention.

  First, in step (A), a catalyst ink is prepared, and this catalyst ink is applied and dried on a transfer mount to obtain a transfer sheet on which the catalyst layers 4a and 4c are formed on the transfer mount. In this case, the transfer mount is not particularly limited, and a known sheet such as a polyester sheet such as a PTFE (polytetrafluoroethylene) sheet or a PET (polyethylene terephthalate) sheet can be used. 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).

  The catalyst ink used in the above method includes a solvent, an electrolyte, and a catalyst component. The catalyst component used for the cathode catalyst layer 4c is not particularly limited as long as it has a catalytic action for the oxygen reduction reaction, and a known catalyst can be used in the same manner. Further, the catalyst component used in the anode catalyst layer 4a is not particularly limited as long as it has a catalytic action for the oxidation reaction of hydrogen, and a known catalyst can be used in the same manner. Specifically, it is selected from platinum, ruthenium, iridium, rhodium, palladium, osmium, tungsten, lead, iron, chromium, cobalt, nickel, manganese, vanadium, molybdenum, gallium, aluminum and the like, and alloys thereof. Is done. Among these, those containing at least platinum are preferably used in order to improve catalyst activity, poisoning resistance to carbon monoxide and the like, heat resistance, and the like. The composition of the alloy is preferably 30 to 90 atomic% for platinum and 10 to 70 atomic% for the metal to be alloyed, depending on the type of metal to be alloyed. The composition of the alloy when the alloy is used as the cathode catalyst varies depending on the type of metal to be alloyed and can be appropriately selected by those skilled in the art, but platinum is 30 to 90 atomic%, and other metals to be alloyed are 10 to 70. It is preferable to use atomic%. In general, an alloy is a generic term for an element obtained by adding one or more metal elements or non-metal elements to a metal element and having metallic properties. The alloy structure consists of a eutectic alloy, which is a mixture of the component elements as separate crystals, a component element completely melted into a solid solution, and a component element composed of an intermetallic compound or a compound of a metal and a nonmetal. In the present invention, any of them may be used. At this time, the catalyst component used for the anode catalyst layer 4a and the catalyst component used for the cathode catalyst layer 4c can be appropriately selected from the above. In the following description, unless otherwise specified, the descriptions of the catalyst components for the anode catalyst layer 4a and the cathode catalyst layer 4c have the same definition for both, and are collectively referred to as “catalyst components”. However, the catalyst components for the anode catalyst layer 4a and the cathode catalyst layer 4c do not have to be the same, and are appropriately selected so as to exhibit the desired action as described above.

  The shape and size of the catalyst component are not particularly limited, and the same shape and size as known catalyst components can be used, but 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 is also high, but in practice the average particle diameter is too small. On the other hand, a phenomenon in which the oxygen reduction activity decreases is observed. 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, still more preferably 2 to 10 nm, and particularly preferably 2 to 5 nm. It is preferably 1 nm or more from the viewpoint of easy loading, and preferably 30 nm or less from the viewpoint of catalyst utilization. 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 microscope image obtained from the half-value width of the diffraction peak of the catalyst component in X-ray diffraction. Can be measured.

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

  The conductive carrier may have any specific surface area for supporting the catalyst particles in a desired dispersed state and has sufficient electronic conductivity as a current collector. The main component is carbon. Preferably there is. Specific examples include carbon particles made of carbon black, activated carbon, coke, natural graphite, artificial graphite and the like. 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 only and a substantially carbon atom. In some cases, elements other than carbon atoms may be included in order to improve the characteristics of the fuel cell. In addition, being substantially composed of carbon atoms means that mixing of impurities of about 2 to 3% by mass or less is allowed.

Although the BET specific surface area of the said electroconductive support | carrier should just be a specific surface area sufficient to carry | support a catalyst component highly dispersed, Preferably it is 20-1600m < ² > / g, More preferably, it is 80-1200m < ² > / g. The specific surface area of 20 m 2 / ^g or more it is sufficient power generation performance dispersibility of the electrolyte component does not lower the catalytic component and later in the conductive support obtained, catalyst component and is not more than 1600 m 2 / ^g It is avoided that the effective utilization rate of the electrolyte component is reduced.

  Further, the size of the conductive carrier is not particularly limited, but from the viewpoint of controlling the ease of loading, the catalyst utilization, and the thickness of the catalyst layer within an appropriate range, the average particle size is 5 to 200 nm, The thickness is preferably about 10 to 100 nm.

  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 70% by mass with respect to the total amount of the electrode catalyst. Good. 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. . Further, 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 supported amount of the catalyst component can be measured by inductively coupled plasma emission spectroscopy (ICP).

  The catalyst component can be supported on the conductive carrier by a known method. For example, known methods such as impregnation method, liquid phase reduction support method, evaporation to dryness method, colloid adsorption method, spray pyrolysis method, reverse micelle (microemulsion method) can be used. Alternatively, a commercially available electrode catalyst may be used.

  The anode catalyst layer 4a / cathode catalyst layer 4c (hereinafter also simply referred to as “catalyst layer”) of the present invention contains a polymer electrolyte in addition to the electrode catalyst. The polymer electrolyte is not particularly limited, and the same polymer electrolyte as that used for the electrolyte membrane 2 can be used. The polymer electrolyte used for the electrolyte membrane 2 and the polymer electrolyte used for the catalyst layers 4a and 4c may be the same or different, but the catalyst layers 4a and 4c and the electrolyte membrane 2 From the viewpoint of improving the adhesiveness, it is preferable to use the same one. That is, the polymer electrolyte is not particularly limited and a known one can be used, but any member having at least high proton conductivity may be used. The polymer electrolyte that can be used in this case is roughly classified into a fluorine-based electrolyte that contains fluorine atoms in the whole or a part of the polymer skeleton and a hydrocarbon-based electrolyte that does not contain fluorine atoms in the polymer skeleton.

  Specific examples of the fluorine electrolyte include perfluorocarbon sulfonic acids such as Nafion (registered trademark, manufactured by DuPont), Aciplex (registered trademark, manufactured by Asahi Kasei Co., Ltd.), and Flemion (registered trademark, manufactured by Asahi Glass Co., Ltd.). Polymer, polytrifluorostyrene sulfonic acid polymer, perfluorocarbon phosphonic acid polymer, trifluorostyrene sulfonic acid polymer, ethylene tetrafluoroethylene-g-styrene sulfonic acid polymer, ethylene-tetrafluoroethylene copolymer, polyvinylidene A preferred example is a fluoride-perfluorocarbon sulfonic acid-based polymer.

  Specific examples of the hydrocarbon electrolyte include polysulfone sulfonic acid, polyaryl ether ketone sulfonic acid, polybenzimidazole alkyl sulfonic acid, polybenzimidazole alkyl phosphonic acid, polystyrene sulfonic acid, polyether ether ketone sulfonic acid, polyphenyl. A suitable example is sulfonic acid.

  The polymer electrolyte preferably contains a fluorine atom because of its excellent heat resistance and chemical stability. Among them, Nafion (registered trademark, manufactured by DuPont), Aciplex (registered trademark, manufactured by Asahi Kasei Co., Ltd.) Fluorine electrolytes such as Flemion (registered trademark, manufactured by Asahi Glass Co., Ltd.) are preferred.

  In the method of the present invention, the catalyst layers 4a and 4c are formed by applying the catalyst ink comprising the electrode catalyst, the polymer electrolyte and the solvent as described above to the gas diffusion layers 5a and 5c. In this case, the solvent is not particularly limited, and ordinary solvents used for forming the catalyst layers 4a and 4c can be used in the same manner. Specifically, water, lower alcohols such as cyclohexanol, ethanol and 2-propanol can be used. Also, the amount of solvent used is not particularly limited, and the same amount as known can be used. In the catalyst ink, the electrode catalyst has a desired action, that is, hydrogen oxidation reaction (anode side) and oxygen reduction reaction. Any amount may be used as long as it can sufficiently exert the action of catalyzing (cathode side). It is preferable that the electrode catalyst is present in the catalyst ink in an amount of 5 to 30% by mass, more preferably 9 to 20% by mass.

  The catalyst ink of the present invention may contain a thickener. The use of a thickener is effective when the catalyst ink cannot be successfully applied onto the gas diffusion layer. The thickener that can be used in this case is not particularly limited, and a known thickener can be used. Examples thereof include glycerin, ethylene glycol (EG), polyvinyl alcohol (PVA), and propylene glycol (PG). The amount of the thickener added when the thickener is used is not particularly limited as long as it does not interfere with the above effect of the present invention, but is preferably 5 to 20 with respect to the total mass of the catalyst ink. % By mass.

  The catalyst ink of the present invention is not particularly limited in its preparation method as long as an electrode catalyst, an electrolyte and a solvent, and if necessary, a water-repellent polymer and / 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 mixed solution to dissolve the electrolyte in the polar solvent, and then adding an electrode catalyst thereto. Alternatively, after the electrolyte is once dispersed / suspended in a solvent, the dispersion / suspension may be mixed with an electrode catalyst to prepare a catalyst ink. In addition, a commercially available electrolyte solution (for example, a Nafion solution manufactured by DuPont: Nafion dispersed / suspended at a concentration of 5 wt% in 1-propanol) is prepared as it is. You may use for the said method.

  The catalyst ink as described above is applied onto the transfer mount to form the catalyst layers 4a and 4c. At this time, the formation conditions of the anode catalyst layer 4a / cathode catalyst layer 4c on the transfer mount are not particularly limited, and can be used in the same manner or with appropriate modifications. For example, the catalyst ink is applied onto a transfer mount so that the thickness after drying is 5 to 20 μm, and is 25 to 150 ° C., more preferably 60 to 120 ° C. in a vacuum dryer or under reduced pressure. For 5 to 30 minutes, more preferably 10 to 20 minutes. In addition, in the said process, when the thickness of the catalyst layers 4a and 4c is not enough, the said application | coating and drying process is repeated until it becomes desired thickness.

  Next, in step (a), the anode and cathode transfer sheet formed in (a) above is used to sandwich the electrolyte membrane 2 whose lateral outer peripheral portion is sealed with the water vapor seal member 3, and then hot pressing is performed. Thereafter, the transfer mount is peeled off to obtain a laminate of the anode catalyst layer 4a and the electrolyte membrane 2-cathode catalyst layer 4c sealed with the water vapor seal member 3. At this time, the hot press conditions are not particularly limited as long as the catalyst layers 4a and 4c, the water vapor seal member 3 and the electrolyte membrane 2 can be joined sufficiently closely, but are 100 to 200 ° C, more preferably 110 to 170 ° C. It is preferable to carry out at a pressing pressure of 1 to 5 MPa against the surface of the electrodes (catalyst layers 4a and 4c). As a result, the bonding property between the polymer electrolyte membrane 2 (further including a part of the water vapor seal member 3 in some embodiments such as FIGS. 1E to 1F and 5A to 5) and the catalyst layers 4a and 4c is improved. Can be increased. After performing the hot press, the laminate of the electrolyte membrane 2 sealed by the catalyst layers 4a and 4c and the water vapor seal member 3 can be obtained by peeling off the transfer mount and peeling off the transfer mount.

  Further, in step (c), gas diffusion layers (GDL) 5c and 5a are disposed on the anode catalyst layer 4a and the cathode catalyst layer 4c, respectively, so that the gas diffusion layers 5c and 5a, the catalyst layers 4c and 4a, and the water vapor seal member are disposed. A laminate of the electrolyte membrane 2 sealed with 3 is obtained. Specifically, the laminate (a) is further sandwiched between the gas diffusion layers 5c and 5a, and if necessary, sandwiched and bonded by hot pressing. At this time, the gas diffusion layers 5c and 5a are not particularly limited, and known ones can be used in the same manner. For example, the gas diffusion layers 5c and 5a have conductivity and porosity such as carbon woven fabric, paper-like paper body, felt, and non-woven fabric. The thing which uses a sheet-like material as a base material etc. are mentioned. 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, more preferably in consideration of mechanical strength and gas and water permeability. Is 50-300 μm.

  The gas diffusion layers 5c and 5a preferably contain a water repellent in the base material for the purpose of further improving water repellency and preventing a flooding phenomenon. Although it does not specifically limit as said water repellent, Fluorine-type, such as polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), polyhexafluoropropylene, tetrafluoroethylene-hexafluoropropylene copolymer (FEP), etc. Examples thereof include polymer materials, polypropylene, and polyethylene.

  In order to further improve water repellency, the gas diffusion layers 5c and 5a may have a carbon particle layer made of an aggregate of carbon particles containing a water repellent on the substrate.

  The carbon particles are not particularly limited, and may be conventional ones such as carbon black, graphite, and expanded graphite. 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 100 nm. Thereby, while being able to obtain the high drainage property by capillary force, it becomes possible to also improve the contact property with catalyst layer 4a, 4c.

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

  In the carbon particle layer, the mixing ratio of the carbon particles to the water repellent may be insufficient to obtain water repellency as expected when there are too many carbon particles. If there are too many water repellents, sufficient electron conductivity may be obtained. There is a risk that it will 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.

  The thickness of the carbon particle layer may be appropriately determined in consideration of the water repellency of the obtained gas diffusion layers 5c and 5a.

  When the gas diffusion layers 5c and 5a contain a water repellent, a general water repellent treatment method may be used. For example, after immersing the base material used for gas diffusion layers 5c and 5a in the dispersion liquid of a water repellent, the method of heat-drying in oven etc. is mentioned.

  In the case of forming a carbon particle layer on the transfer mount in the gas diffusion layers 5c and 5a, carbon particles, a water repellent, etc. are used as alcohol solvents such as water, perfluorobenzene, dichloropentafluoropropane, methanol and ethanol. A slurry is prepared by dispersing in a solvent such as the above, and the slurry is applied on a transfer mount and dried, or the slurry is once dried and pulverized to form a powder, which is converted into the gas diffusion layer 5c, What is necessary is just to use the method of apply | coating on 5a. Then, it is preferable to heat-process at about 250-400 degreeC using a muffle furnace or a baking furnace.

  Subsequently, in step (d), adhesive layers (adhesive portions) 7a and 7c and gaskets 6a and 6c are formed at predetermined positions of the electrolyte membrane 2 sealed by the water vapor seal member 3, respectively.

  At this time, the material that can be used for the adhesive layers (adhesive portions) 7a, 7c is the water vapor seal member 3 (as shown in FIGS. 1B to 1D, 1F to 1G, 2A to 2B, and 6A to 6B). In some embodiments, a part of the electrolyte membrane 2 is included, and the gaskets 6a, 6c (similarly, in some embodiments as described above, part of the gas diffusion layers 5c, 5a) can be closely bonded. Although it will not restrict | limit especially if it is a thing, Hot melt type adhesives, such as polyolefin, a polypropylene, a thermoplastic elastomer, Acrylic adhesives, Olefin type adhesives, such as polyester and polyolefin, etc. can be used. When the water vapor seal member 3 is formed of an adhesive, the adhesive used for the water vapor seal member 3 and the adhesive layers (adhesive portions) 7a and 7c may be the same or different. .

  7A to 7C are diagrams for explaining one step of the method for producing the MEA of the present invention. In FIG. 7A, the configuration on the anode side is paired with the configuration on the cathode side (the target shape) and is not shown (see FIG. 1B for details). The same applies to FIGS. 7B and 7C described later.

  When the adhesive used for the water vapor seal member 3 and the adhesive layers (adhesive portions) 7a and 7c is the same, as shown in FIG. 7A, the electrolyte that does not have the water vapor seal member 3 in the above step (c). Using the membrane 2, in this step (D), as shown in FIG. 7B, a step of forming a water vapor seal member 3 at a predetermined portion of the electrolyte membrane 2 and an adhesive layer (adhesive portion) 7c (7a; not shown) ) May be performed. The thicknesses of the adhesive layers (adhesive portions) 7a and 7c are the same as the catalyst layers 4a and 4c as shown in FIGS. 1B to 1G (= the outer peripheral portions in the surface direction of the anode catalyst layer 4a and the cathode catalyst layer 4b; In other words, it may be disposed on the same surface as the catalyst layers 4a and 4c), but may be thicker than the catalyst layers 4a and 4c, so as defined in the present invention, the anode catalyst layer 4a and The cathode catalyst layer 4b is not particularly limited as long as it is arranged on at least the outer peripheral portion in the surface direction, in other words, at least on the same surface as the catalyst layers 4a and 4c so as to prevent gas leakage from the side surface of the catalyst layer. . Furthermore, the water vapor sealing member 3 (including a part of the electrolyte membrane 2 in some embodiments) and the gaskets 6a and 6c (also including a part of the gas diffusion layers 5c and 5a in some embodiments). The thickness is desirably such that sufficient adhesion can be achieved, and is preferably 5 to 30 μm, more preferably 10 to 25 μm.

  Thereafter, as shown in FIG. 7C, a gasket 6c (6a; not shown) is formed on the adhesive layer (adhesive portion) 7c (7a; not shown) of the gas diffusion layer 5c (5a; not shown). It is formed so as to be in contact with the end portion (in some cases, with a gap 11 as shown in FIGS. 6A to 6B).

  At this time, the gaskets 6a and 6c are made of a material that is impermeable to gas, particularly oxygen gas, hydrogen gas, and water vapor. The gas impermeable material that can be used in this case is not particularly limited as long as it is impermeable to oxygen and hydrogen gas when formed into a film. Specific examples include polyethylene naphthalate (PEN), polyethylene terephthalate (PET), polytetrafluoroethylene (PTFE), and polyvinylidene fluoride (PVDF). Moreover, the formation method in particular of a gasket is not restrict | limited, A well-known method can be used. For example, the gas-impermeable material as described above is applied on the adhesive layers (adhesive portions) 7a and 7c of the seal so as to have a predetermined thickness, and this is heated at 25 to 150 ° C. for 10 seconds to 10 minutes. The curing method can be used. Alternatively, after the gas-impermeable material is formed into a sheet shape in advance, an electrolyte membrane 2 in which the impermeable film is bonded onto the adhesive layers (adhesive portions) 7a and 7c of the seal is sealed with the water vapor seal member 3. You may arrange on top. At this time, the thickness of the gaskets 6a and 6c is not particularly 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 projecting portions 8a and 8c for sealing are formed on the gaskets 6a and 6c, and are further sandwiched by the separator. Compressive stress is applied to 8a and 8c. Here, by setting the height of the gaskets 6a and 6c before being sandwiched by the separator to be lower than the height of the gas diffusion layers 5a and 5c, the adhesion between the separator and the gas diffusion layers 5a and 5c is improved, and the fuel The channel and the oxidant channel can be reliably formed, and the conductivity of the gas diffusion layers 5a and 5c and the separator can be secured. For this reason, the gaskets 6a and 6c are preferably formed to be lower than the height of the gas diffusion layers 5a and 5c. For this reason, the thickness of gasket 6a, 6c becomes like this. More preferably, it is 10-200 micrometers, Most preferably, it is 15-40 micrometers.

  In the above description, the method for forming the anode / cathode catalyst layer on the electrolyte membrane by the transfer method has been described. However, the MEA 1 of the present invention can be applied to other methods such as a direct coating method in which the catalyst ink is directly printed on the electrolyte membrane 2. It may be manufactured by a method. That is, in the present invention, the catalyst layers 4a and 4c, the gas diffusion layers 5a and 5c, and the adhesive layer (adhesive part) of the seal are formed on a predetermined position of the electrolyte membrane 2 whose side outer peripheral part is sealed with the water vapor seal member 3. ) 7a and 7c and gaskets 6a and 6c may be formed on the surfaces of the respective anodes and cathodes, and the details of each step can be applied since the same method as described above can be applied.

  As described above, the electrolyte membrane-electrode assembly of the present invention suppresses / prevents drying of the electrolyte membrane due to water vapor permeation, and effectively suppresses membrane breakage due to compressive stress at the bonding surface between the gas diffusion layer and the gasket. It is possible to prevent. Therefore, by using such an electrolyte membrane-electrode assembly, it is possible to provide a highly reliable fuel cell that has a simple manufacturing process and excellent durability.

  The type of the fuel cell is not particularly limited. In the above description, the polymer electrolyte fuel cell has been described as an example, but in addition to this, a representative example is an alkaline fuel cell and a phosphoric acid fuel cell. Examples thereof include an acid electrolyte fuel cell, a direct methanol fuel cell, and a micro fuel cell. Among them, a polymer electrolyte fuel cell is preferable because it is small in size, and can achieve high density and high output. The fuel cell is useful as a stationary power source in addition to a power source for a moving body such as a vehicle in which a mounting space is limited. However, the fuel cell is particularly useful for an automobile application in which system start / stop and output fluctuation frequently occur. It can be particularly preferably used.

  The polymer electrolyte fuel cell is useful not only as a stationary power source but also as a power source for a moving body such as an automobile having a limited mounting space. In particular, moving bodies such as automobiles that are susceptible to corrosion of the carbon support due to the high output voltage required after a relatively long shutdown, and 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 power source.

  The configuration of the fuel cell is not particularly limited, and a conventionally known technique may be used as appropriate. Generally, the fuel cell has a structure in which an MEA is sandwiched between separators.

  The separator can be used without limitation as long as it is conventionally known, such as those made of carbon such as dense carbon graphite and a carbon plate, and those made of metal such as stainless steel. The separator has a function of separating air and fuel gas, and a channel groove for securing the channel may be formed. The thickness and size of the separator, the shape of the flow channel, and the like are not particularly limited, and may be appropriately determined in consideration of the output characteristics of the obtained fuel cell.

  Further, in order to prevent the gas supplied to the catalyst layers 4a and 4c from leaking to the outside, the portions where the catalyst layers 4a and 4c are not formed on the gaskets 6a and 6c (for example, the gaps 10 and 11). ) May further be provided with a gas seal (not shown). Examples of the material constituting the gas seal portion include rubber materials such as fluoro rubber, silicon rubber, ethylene propylene rubber (EPDM), polyisobutylene rubber, polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), polyhexafluoro. Fluorine polymer materials such as propylene, tetrafluoroethylene-hexafluoropropylene copolymer (FEP), and thermoplastic resins such as polyolefin and polyester. The thickness of the gas seal portion may be 2 mm to 50 μm, preferably about 1 mm to 100 μm.

  Furthermore, a stack in which a plurality of MEAs are stacked via a separator and connected in series 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.

  The electrolyte membrane-electrode assembly (MEA) of the present invention can be applied to a fuel cell having excellent durability and good fuel efficiency.

It is a figure explaining the side outer periphery part and outermost periphery part of the electrolyte membrane in MEA of this invention. It is a figure which shows an example of arrangement | positioning of the water vapor | steam sealing member in the electrolyte membrane in MEA of this invention. It is a figure which shows an example of arrangement | positioning of the water vapor | steam sealing member in the electrolyte membrane in MEA of this invention. It is a figure which shows an example of arrangement | positioning of the water vapor | steam sealing member in the electrolyte membrane in MEA of this invention. It is a figure which shows an example of arrangement | positioning of the water vapor | steam sealing member in the electrolyte membrane in MEA of this invention. It is a figure which shows an example of arrangement | positioning of the water vapor | steam sealing member in the electrolyte membrane in MEA of this invention. It is a figure which shows an example of arrangement | positioning of the water vapor | steam sealing member in the electrolyte membrane in MEA of this invention. It is a figure explaining the positional relationship of the water vapor | steam sealing member and the convex part (lip) for a seal | sticker in MEA of this invention. It is a figure explaining the water vapor | steam sealing member in MEA of this invention, and the convex part for a seal | sticker (lip positional relationship. It is a figure explaining the positional relationship in which the electrolyte membrane and water vapor | steam sealing member in MEA of this invention are formed. It is a figure explaining the positional relationship in which the electrolyte membrane and water vapor | steam sealing member in MEA of this invention are formed. It is a figure explaining the positional relationship in which the electrolyte membrane and water vapor | steam sealing member in MEA of this invention are formed. It is sectional drawing of MEA of this invention in case a gasket and a water vapor | steam sealing member are formed integrally. It is sectional drawing of MEA of this invention in case it has a reinforcement member as a water vapor | steam sealing member. It is sectional drawing of MEA of this invention in case it has a reinforcement member. It is sectional drawing of MEA of this invention in case it has the reinforcement member which has adhesiveness as a seal | sticker. It is sectional drawing of MEA of this invention in case it has a reinforcement member and a reinforcement layer. It is sectional drawing of MEA of this invention when the contact bonding layer (bonding part) of a seal | sticker is formed inside an electrolyte membrane beyond a gasket. It is sectional drawing of MEA of this invention when the contact bonding layer (bonding part) of a seal | sticker is formed inside an electrolyte membrane beyond a gasket. 7A to 7C are diagrams for explaining one step of the method for producing the MEA of the present invention.

Explanation of symbols

1 ... electrolyte membrane-electrode assembly (MEA),
2 ... electrolyte membrane,
3 ... water vapor seal member (or a reinforcing member as a water vapor seal member),
3 '... reinforcement layer,
3 / 6a in which a water vapor seal member and an anode side gasket are integrally formed,
3 / 7a / 7c seal (reinforcing member in which a water vapor seal member and an adhesive layer are integrally formed),
4a ... anode catalyst layer,
4c ... cathode catalyst layer,
5a ... first gas diffusion layer on the anode side,
5c ... the second gas diffusion layer on the cathode side,
6a ... Anode side gasket,
6c ... gasket on the cathode side,
7a ... Adhesive part or adhesive layer on the anode side,
7c ... Adhesive part or adhesive layer on the cathode side,
8a: A convex portion (lip) for sealing on the anode side,
8c: convex part (lip) for sealing on the cathode side,
9a ... anode side joining surface,
9c ... cathode side joint surface,
10, 11 ... Gap.

Claims (12)

An electrolyte membrane;
An anode catalyst layer provided on one surface of the electrolyte membrane;
A cathode catalyst layer provided on the other surface of the electrolyte membrane;
Seals for preventing gas leakage from the side surfaces of the anode catalyst layer and the cathode catalyst layer, and the side surfaces of the electrolyte membrane;
A gasket provided on both sides 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 a side surface of the anode catalyst layer on an outer peripheral part in a surface direction of the anode catalyst layer and the cathode catalyst layer. And an electrolyte membrane-electrode assembly disposed so as to prevent gas leakage from the side surface of the cathode catalyst layer.   The electrolyte membrane-electrode assembly according to claim 1, wherein the seal is disposed so as to include at least a part of an outermost peripheral portion of the electrolyte membrane. The seal comprises a water vapor seal member that prevents gas leakage from the side surface of the electrolyte membrane, and an adhesive layer that adheres the water vapor seal member or the electrolyte membrane 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 electrolyte membrane-electrode according to claim 1, 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 electrolyte membrane-electrode assembly according to claim 1, wherein the water vapor seal member is made of a material having a higher compressive elastic modulus than the electrolyte membrane.   The electrolyte membrane-electrode assembly according to claim 5, wherein the water vapor seal member is made of the same material as that of the gasket.   The electrolyte membrane-electrode assembly according to claim 1, wherein the water vapor seal member and the gasket are integrally formed. The portion arranged to prevent leakage of gas from the side surface of the electrolyte membrane that is a part of the seal is a reinforcing member having higher strength than the electrolyte membrane,
The reinforcing member includes an electrolyte so as to include a bonding surface between a gas diffusion layer and a gasket further formed on the anode catalyst layer and / or the cathode catalyst layer with respect to the thickness direction of the electrolyte membrane-electrode assembly. The electrolyte membrane-electrode assembly according to any one of claims 1 to 7, which is disposed on at least a part of a lateral outer peripheral portion of the membrane. A first gas diffusion layer further formed on the anode catalyst layer and a second gas diffusion layer further formed on the cathode catalyst layer with respect to the thickness direction of the electrolyte membrane-electrode assembly. In addition,
The seal includes a reinforcing member that prevents leakage of gas from the side surface of the electrolyte membrane and has a higher strength than the electrolyte membrane, and an adhesive layer that bonds the reinforcing member or the electrolyte membrane to the gasket. ,
The reinforcing member is formed on the inner side of the electrolyte membrane than any one of a joint surface between the first gas diffusion layer and the gasket or a joint surface between the second gas diffusion layer and the gasket. Item 9. The electrolyte membrane-electrode assembly according to any one of Items 1 to 8.   An intermediate layer of the electrolyte membrane is formed such that a reinforcing layer having a higher strength than the electrolyte membrane overlaps at least a part of the anode catalyst layer and / or the cathode catalyst layer in the thickness direction of the electrolyte membrane-electrode assembly. The electrolyte membrane-electrode assembly according to any one of claims 1 to 9, which is disposed in a portion.   The electrolyte membrane-electrode assembly according to any one of claims 1 to 10, wherein an area of the anode catalyst layer is larger than an area of the cathode catalyst layer.   A fuel cell using the electrolyte membrane-electrode assembly according to any one of claims 1 to 11.

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