JP2008146932A - Membrane-electrode assembly, and polymer electrolyte fuel cell equipped with this - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a membrane-electrode assembly preventing breakage of a polymer electrolyte membrane. <P>SOLUTION: The membrane-electrode assembly 10 has a plate-like first gas diffusion electrode 8 which contains a first gas diffusion layer 4 and a first catalyst layer 2 stacked with the first gas diffusion layer, having the main surface wider than that of the first gas diffusion layer and whose outer peripheral part is protruded than the main surface, and a plate-like second gas diffusion electrode 9 facing the first gas diffusion electrode 8. The membrane-electrode assembly 10 furthermore has a polymer electrolyte membrane 1 having the main surface wider than that of the first catalyst layer, a picture frame-like first frame extending along the outer periphery in the outer peripheral part of the main surface on the first catalyst layer side of the polymer electrolyte membrane and whose inner peripheral part is inserted between the polymer electrolyte membrane and the outer peripheral part of the first catalyst layer, and a picture frame-like first gas seal member 11 interposing the outer peripheral part of the first catalyst layer between the first frame and itself and arranged so as not to overlap with the first gas diffusion layer although it is present in the periphery of the first gas diffusion layer. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a membrane-electrode assembly including a polymer electrolyte membrane and a polymer electrolyte fuel cell including the membrane-electrode assembly used in a polymer electrolyte fuel cell, and in particular, can prevent damage to the polymer electrolyte membrane. The present invention relates to a membrane-electrode assembly.

Conventionally, membrane-electrode assemblies have been used in polymer electrolyte fuel cells. The membrane-electrode assembly includes a polymer electrolyte membrane and a pair of electrodes (gas diffusion electrodes) disposed on both sides of the polymer electrolyte membrane. Here, as a technique for preventing breakage of the polymer electrolyte membrane, as shown in Patent Document 1, a frame-shaped protective membrane that is arranged in close contact with the peripheral portion of the polymer electrolyte membrane and has an overlap with the electrode, A seal structure provided on at least one main surface side of a polymer electrolyte membrane is disclosed.
Japanese Patent Laid-Open No. 5-21077

  However, the configuration of Patent Document 1 has a problem that damage to the outer peripheral edge of the polymer electrolyte membrane cannot be sufficiently suppressed.

  The present invention has been made to solve the above-described problems, and a membrane-electrode assembly in which damage to the outer peripheral edge of the polymer electrolyte membrane is sufficiently suppressed, and a polymer electrolyte fuel provided with the membrane-electrode assembly An object is to provide a battery.

  The inventors of the present invention have intensively studied to solve the above problems.

  As a result, in the configuration of Patent Document 1, in the gas diffusion electrode, the progress of the damage due to the heat generation at the outer peripheral edge is larger than that at the center, and the protective film and the polymer electrolyte membrane near the outer peripheral edge are damaged. There was still room for improvement as it progressed easily.

  That is, when the protective film is disposed on the polymer electrolyte membrane so as to overlap the peripheral part of the gas diffusion electrode, the peripheral part of the gas diffusion electrode where the protective film exists is the central part where the protective film does not exist Compared to the above, the generated water generated by the battery reaction is less likely to be supplied. Therefore, the peripheral part of the gas diffusion electrode is easier to dry than the central part. As a result, at the periphery of the gas diffusion electrode, in addition to the electrochemical reaction of the reaction gas, a combustion reaction of the reaction gas on the catalyst (a fuel gas and an oxidant gas that cross over each other and cross over each other in the polymer electrolyte membrane) Combustion reaction), the heat of reaction due to the combustion reaction is more likely to be transferred to the polymer electrolyte membrane near the periphery of the gas diffusion electrode, compared to the center of the gas diffusion electrode where the produced water is sufficiently present, The polymer electrolyte membrane was easily damaged by heat.

  In particular, in the case of the membrane-electrode assembly of Patent Document 1, a gap is formed between the outer edge of the gas diffusion electrode and the inner edge of the gas seal member disposed around the gas diffusion electrode (Patent Document 1, gap 8 in FIG. 1). Therefore, it is considered that the reaction gas passing through the gap tends to make the influence of the combustion reaction at the peripheral edge of the gas diffusion electrode more prominent.

  Therefore, in order to solve the above-described problem, the membrane-electrode assembly of the present invention includes a first gas diffusion layer having gas diffusibility and the first gas diffusion layer which are laminated with each other. A first catalyst layer having a major surface with a larger area than the first major surface, and a first catalyst layer disposed so that an outer peripheral edge thereof protrudes outside the first gas diffusion layer. A diffusion electrode; a flat plate-like second gas diffusion electrode disposed opposite to the first gas diffusion electrode; and the first catalyst layer and the second gas diffusion electrode. A polymer electrolyte membrane having a principal surface with an area equal to or greater than the principal surface of the layer, and extending along the outer periphery to the outer peripheral edge of the principal surface of the polymer electrolyte membrane on the first catalyst layer side; The peripheral portion is disposed so as to be inserted between the polymer electrolyte membrane and the outer peripheral portion of the first catalyst layer. An outer peripheral edge of the first frame body having an edge shape and the first catalyst layer is sandwiched between the first frame body, and around the first gas diffusion layer and in the first gas diffusion layer. And a frame-shaped first gas seal member arranged so as not to overlap (Claim 1).

  As described above, when the first gas diffusion electrode is configured to include the first gas diffusion layer and the first catalyst layer, the entire outer peripheral edge of the first catalyst layer protrudes beyond the first gas diffusion layer. Unlike the configuration of Patent Document 1, the combustion reaction occurs exclusively in the entire outer peripheral edge portion of the first catalyst layer. For this reason, the fuel reaction described above is performed on the entire outer peripheral edge portion of the first catalyst layer protruding outside. Heat can be dispersed. Therefore, thermal damage of the polymer electrolyte membrane due to the influence of combustion reaction heat can be suppressed.

  Further, when the outer peripheral edge portion of the first catalyst layer is sandwiched between the first gas seal member and the first frame body, it becomes easy to laminate and manufacture the membrane-electrode assembly.

  In the membrane-electrode assembly according to the present invention, the back surface (surface on the polymer electrolyte membrane side) of the outer peripheral edge of the first catalyst layer that protrudes outside the first catalyst layer is covered with the first frame. The gas seal member is disposed on the outer peripheral edge of the first catalyst layer that protrudes outward from the first catalyst layer. Therefore, unlike the configuration of Patent Document 1, the membrane-electrode assembly of the present invention has no gap between the first gas diffusion electrode and the gas seal member. By disposing the first frame body between the outer peripheral edge of the polymer electrolyte membrane and the outer peripheral edge of the first catalyst layer as described above, the outer peripheral edge of the polymer electrolyte membrane is damaged by the heat of combustion reaction. It can be hard to happen.

  Furthermore, since the first frame and the first catalyst layer are interposed between the first gas diffusion layer and the first gas seal member and the polymer electrolyte membrane, the outer end of the first gas diffusion layer and the first 1 The inner end of the gas seal member is prevented from damaging the polymer electrolyte membrane. Thereby, when the membrane-electrode assembly is fastened together with the separator, breakage of the polymer electrolyte membrane due to mechanical stress is further suppressed.

  A frame-like second gas seal member may be further provided around the second gas diffusion electrode so as to face the first gas seal member.

  The second gas diffusion electrode is configured to include a second gas diffusion layer having gas diffusivity, and a second catalyst layer disposed between the second gas diffusion layer and the polymer electrolyte membrane. When viewed from the thickness direction of the second catalyst layer, the outer edge of the second catalyst layer may be located between the inner edge and the outer edge of the first frame (Claim 3).

  The second catalyst layer has a major surface larger than the major surface of the second gas diffusion layer, and the outer peripheral edge of the second catalyst layer may be disposed so as to protrude outward from the second gas diffusion layer. Good (Claim 4).

  The outer periphery of the main surface of the polymer electrolyte membrane on the second catalyst layer side extends along the outer periphery, and the inner periphery thereof is the outer periphery of the polymer electrolyte membrane and the second catalyst layer. A frame-shaped second frame disposed so as to be inserted between the second frame and an outer peripheral edge of the second catalyst layer between the second frame and the second gas diffusion layer And a frame-shaped second gas seal member arranged so as not to overlap the second gas diffusion layer (Claim 5).

  Preferably, the first gas diffusion electrode is an anode. As described above, by adopting the above-described configuration according to the present invention on the anode side, as a method of operating the polymer electrolyte fuel cell using the membrane-electrode assembly of the present invention, the power generation is stopped and started as in the so-called DSS operation. When the operation method is repeated, a part of the oxidant gas (for example, oxygen) at the cathode moves to the anode through the polymer electrolyte membrane between the stop of power generation and the next startup, and the above-mentioned on the catalyst at the anode. Even when the combustion reaction is possible, damage to the polymer electrolyte membrane can be sufficiently suppressed. In addition, even when the anode side is air bleeded and the combustion reaction on the catalyst is possible, the polymer electrolyte membrane is sufficiently damaged by adopting the above-described configuration of the present invention for the anode. Can be suppressed.

  An outer peripheral edge portion of the polymer electrolyte membrane may protrude outside the first catalyst layer and the second gas diffusion electrode (Claim 7).

  With such a configuration, the first frame and the first gas seal member are disposed on the outer peripheral edge of the polymer electrolyte membrane, so that the gas sealability when fastened with the separator is further improved. Moreover, since the second frame and the second seal member are disposed on the outer peripheral edge of the polymer electrolyte membrane, the gas sealability when fastened by the separator is further improved.

  A gap may be provided between an outer edge of the first gas diffusion layer and an inner edge of the first gas seal member (Claim 8).

  A gap may be provided between an outer edge of the second gas diffusion layer and an inner edge of the second gas seal member (claim 9).

  The outer edge of the first gas diffusion layer and the inner edge of the first gas seal member may be in contact with each other so as not to overlap each other (claim 10).

  The outer edge of the second gas diffusion layer and the inner edge of the second gas seal member may be in contact with each other so as not to overlap each other (claim 11).

  The polymer electrolyte fuel cell of the present invention is disposed so as to face any of the membrane-electrode assemblies and the membrane-electrode assembly so as to supply a reaction gas to the membrane-electrode assembly. And a pair of separators in which reaction gas flow paths are formed (claim 12).

  Since the membrane-electrode assembly and the polymer electrolyte fuel cell of the present invention are configured as described above, there is an effect that damage at the outer peripheral edge of the polymer electrolyte membrane is suppressed.

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

(First embodiment)
FIG. 1 is a cross-sectional view showing the configuration of a membrane-electrode assembly according to a first embodiment of the present invention and a polymer electrolyte fuel cell having the same, wherein (a) assembles a polymer electrolyte fuel cell. The previous cross-sectional view, (b) is a cross-sectional view after assembling the polymer electrolyte fuel cell. Hereinafter, the polymer electrolyte fuel cell and the membrane-electrode assembly of the present embodiment will be described with reference to FIG.

  As shown in FIGS. 1A and 1B, the polymer electrolyte fuel cell 100 of the present embodiment includes a first separator 15 and a second separator 17, a first gas seal member 11 and a second gas seal member. 13 and the membrane-electrode assembly 10.

  The 1st separator 15 and the 2nd separator 17 are arrange | positioned so that the membrane-electrode assembly 10 mentioned later may be pinched | interposed. The first separator 15 and the second separator 17 are formed in a flat plate shape. In the first separator 15 and the second separator 17, reaction gas flow paths 15 a and 17 a are formed on the main surface facing the membrane-electrode assembly 10. A cooling water channel (not shown) may be formed on the main surface of the first separator 15 and the second separator 17 opposite to the main surface where the reaction gas channels 15a and 17a are formed. The first separator 15 and the second separator 17 are made of a conductive material such as a graphite material or a metal material.

  The membrane-electrode assembly 10 is disposed between the first separator 15 and the second separator 17. The membrane-electrode assembly 10 includes a polymer electrolyte membrane 1, a first catalyst layer 2 and a second catalyst layer 3 disposed on both main surfaces of the polymer electrolyte membrane 1, a first catalyst layer 2, and The first gas diffusion layer 4 and the second gas diffusion layer 5 laminated on the second catalyst layer 3, respectively, between the polymer electrolyte membrane 1 and the first catalyst layer 2, and between the polymer electrolyte membrane 1 and the second catalyst layer The first frame body 6 and the second frame body 7 are respectively inserted between the first frame body 6 and the second frame body 7.

The polymer electrolyte membrane 1 is formed in a rectangular sheet shape. In the present embodiment, the polymer electrolyte membrane 1 is formed to have a thickness of 30 μm. The thickness of the polymer electrolyte membrane 1 is not particularly limited to 30 μm. The thickness of the polymer electrolyte membrane 1 is preferably 20 μm to 50 μm from the viewpoint of sufficiently reducing the ohmic loss and ensuring sufficient mechanical strength. The polymer electrolyte membrane 1 has proton conductivity. Preferred examples of the polymer electrolyte membrane 1 include those having sulfonic acid groups, carboxylic acid groups, phosphonic acid groups, and sulfonimide groups as cation exchange groups. From the viewpoint of proton conductivity, the polymer electrolyte membrane 1 preferably has a sulfonic acid group, and is represented by CF ₂ = CF— (OCF ₂ CFX) _m —O _p — (CF ₂ ) _n —SO ₃ H. A repeating unit based on a perfluorovinyl compound (m represents an integer of 0 to 3, n represents an integer of 1 to 12, p represents 0 or 1, and X represents a fluorine atom or a trifluoromethyl group) And a perfluorocarbon copolymer containing a repeating unit based on tetrafluoroethylene represented by CF ₂ = CF ₂ is particularly preferred as a polymer electrolyte as a constituent material. In this embodiment, a Nafion membrane (registered trademark; manufactured by DuPont, USA) is used as the polymer electrolyte membrane 1.

  A first catalyst layer 2 and a second catalyst layer 3 are formed on both main surfaces of the polymer electrolyte membrane 1. The first catalyst layer 2 and the second catalyst layer 3 are formed so that the area of the main surface is smaller than the area of the main surface of the polymer electrolyte membrane 1. Specifically, in a state where the first catalyst layer 2 and the second catalyst layer 3 are disposed on the polymer electrolyte membrane 1, the polymer electrolyte membrane 1 and the first catalyst layer 2 and the second catalyst layer 3 overlap each other. The outer peripheral edge of the polymer electrolyte membrane 1 which is not a part is formed in a rectangular ring shape (frame shape) in plan view. In other words, the outer peripheral edge of the first catalyst layer 2 protrudes outside the outer peripheral edge of the first gas diffusion layer 4 described later. Further, the outer peripheral edge of the second catalyst layer 3 protrudes outside the outer peripheral edge of the second gas diffusion layer 5 described later. The configuration of the first catalyst layer 2 and the configuration of the second catalyst layer 3 have a configuration including conductive carbon particles carrying an electrode catalyst and a polymer electrolyte having cation (hydrogen ion) conductivity. Furthermore, you may have the structure which further contains water-repellent materials, such as polytetrafluoroethylene. In addition, as a polymer electrolyte, the same kind as the constituent material of the polymer electrolyte membrane 1 mentioned above may be used, and a different kind may be used. As a polymer electrolyte, what was described as a constituent material of the polymer electrolyte membrane 1 can be used. The electrode catalyst is made of metal particles (for example, metal particles made of noble metal), and is used by being supported on conductive carbon particles (powder). The metal particles are not particularly limited, and various metals can be used. From the viewpoint of electrode reaction activity, platinum, gold, silver, ruthenium, rhodium, palladium, osmium, iridium, chromium, iron, titanium, manganese It is preferably at least one selected from the group consisting of cobalt, nickel, molybdenum, tungsten, aluminum, silicon, zinc and tin. Among these, platinum and an alloy of platinum are preferable, and an alloy of platinum and ruthenium is particularly preferable in the anode because the activity of the catalyst is stabilized.

  A first gas diffusion layer 4 is disposed on the main surface of the first catalyst layer 2 far from the polymer electrolyte membrane 1. A second gas diffusion layer 5 is disposed on the main surface of the second catalyst layer 3 far from the polymer electrolyte membrane 1. The area of the main surface of the first gas diffusion layer 4 is formed to be larger than the area of the inner peripheral edge of the first frame 6 described later and smaller than the area of the main surface of the first catalyst layer 2. Yes. The area of the main surface of the second gas diffusion layer 5 is formed so as to be larger than the area of the inner peripheral edge of the second frame 7 described later and smaller than the area of the main surface of the second catalyst layer 3. Yes.

  In the present embodiment, the first gas diffusion layer 4 and the second gas diffusion layer 5 are formed to have a thickness of 300 μm. The thicknesses of the first gas diffusion layer 4 and the second gas diffusion layer 5 are not particularly limited to 300 μm. The thicknesses of the first gas diffusion layer 4 and the second gas diffusion layer 5 are preferably 100 μm to 400 μm from the viewpoint of sufficiently reducing the ohmic loss and ensuring sufficient mechanical strength. The first gas diffusion layer 4 and the second gas diffusion layer 5 are composed of carbon woven fabric, carbon non-woven fabric, carbon paper, carbon powder sheet, or the like. The first catalyst layer 2 and the first gas diffusion layer 4 are laminated together to constitute a flat plate-like first gas diffusion electrode 8. Further, the second catalyst layer 3 and the second gas diffusion layer 5 are laminated together to constitute a flat plate-like second gas diffusion electrode 9. Thus, the first gas diffusion electrode 8 and the second gas diffusion electrode 9 are arranged so as to face each other with the polymer electrolyte membrane 1 interposed therebetween.

  A first frame 6 is disposed between the first catalyst layer 2 and the polymer electrolyte membrane 1. The first frame body 6 is formed in a rectangular ring shape (frame shape), extends along the outer periphery of the outer peripheral edge portion of the main surface of the polymer electrolyte membrane 1 on the first catalyst layer 2 side, and The inner peripheral edge is disposed so as to be inserted between the polymer electrolyte membrane 1 and the outer peripheral edge of the first catalyst layer 2. A second frame 7 is disposed between the second catalyst layer 3 and the polymer electrolyte membrane 1. The second frame 7 is formed in a rectangular ring shape (frame shape), extends along the outer periphery of the outer peripheral edge of the main surface of the polymer electrolyte membrane 1 on the second catalyst layer 3 side, and The inner peripheral edge portion is disposed so as to be inserted between the polymer electrolyte membrane 1 and the outer peripheral edge portion of the second catalyst layer 3. The first frame body 6 and the second frame body 7 are formed so as to protrude from the outer peripheries of the first catalyst layer 2 and the second catalyst layer 3, respectively.

  In the present embodiment, the first frame body 6 and the second frame body 7 are formed to have a thickness of 15 μm. The thickness of the first frame body 6 and the second frame body 7 is not particularly limited to 15 μm. It is preferable that the thickness of the 1st frame 6 and the 2nd frame 7 is 5 micrometers-50 micrometers from a viewpoint which acquires the effect of this invention more reliably. The materials constituting the first frame 6 and the second frame 7 are polyethylene naphthalate, polytetrafluoroethylene, polyethylene terephthalate, fluoroethylene-propylene copolymer, tetrafluoroethylene-perfluoroalkoxyethylene copolymer, polyethylene. , Polypropylene, polyetheramide, polyetherimide, polyetheretherketone, polyethersulfone, polyphenylene sulfide, polyarylate, polysulfide, polyimide, and at least one synthetic resin selected from the group consisting of polyimideamide Is preferred.

  A first gas seal member 11 and a second gas seal member 13 are disposed between the first separator 15 and the second separator 17 and the membrane-electrode assembly 10. The first gas seal member 11 sandwiches the outer peripheral edge portion of the first catalyst layer 2 with the first frame body 6, and surrounds the first gas diffusion layer 4 around the first gas diffusion layer 4. Arranged so as not to overlap. The second gas seal member 13 sandwiches the outer peripheral edge portion of the second catalyst layer 3 between the second frame body 7 and the second gas diffusion layer 5 around the second gas diffusion layer 5. Arranged so as not to overlap. The first gas seal member 11 and the second gas seal member 13 are formed in a frame shape, that is, in a rectangular ring shape. A gap 21 having a predetermined interval is provided between the inner peripheral edge of the first gas seal member 11 and the outer edge of the first gas diffusion layer 4. A gap 23 having a predetermined interval is provided between the inner peripheral edge of the second gas seal member 13 and the outer edge of the second gas diffusion layer 5. The first gas seal member 11 and the second gas seal member 13 are made of fluorine rubber, silicon rubber, natural rubber, ethylene-propylene rubber (EPDM), butyl rubber, butyl chloride rubber, butyl bromide rubber, butadiene rubber, and styrene-butadiene copolymer. , Ethylene-vinyl acetate rubber, acrylic rubber, polyisopropylene polymer, perfluorocarbon, thermoplastic elastomer (polystyrene elastomer, polyolefin elastomer, polyester elastomer, polyamide elastomer, etc.), latex (isoprene rubber, butadiene rubber, etc.) Adhesive, liquid adhesive (adhesive using polybutadiene, polyisoprene, polychloroprene, silicon rubber, fluorine rubber, acrylonitrile-butadiene rubber, etc.) etc. That.

  Next, the manufacturing method of the membrane-electrode assembly 10 of this embodiment and the polymer electrolyte fuel cell 100 including the same will be briefly described.

  The first frame body 6 is arranged along the outer periphery of the outer peripheral edge of one main surface of the polymer electrolyte membrane 1. Next, the first catalyst layer 2 is applied so as to overlap the inner peripheral edge of the first frame 6. The first catalyst layer 2 is applied such that the outer peripheral edge of the first frame 6 remains in a rectangular ring shape. The first gas diffusion layer 4 is arranged so as to overlap a part of the main surface of the first catalyst layer 2 and the outer peripheral edge of the first catalyst layer 2 remains in a rectangular annular shape.

  Next, in the same manner as described above, the second frame 7 is disposed on the other main surface of the polymer electrolyte membrane 1, the second catalyst layer 3 is applied, and the second gas diffusion layer 5 is disposed.

  That is, the second frame 7 is disposed along the outer periphery of the other main surface of the polymer electrolyte membrane 1 along the outer periphery thereof. Next, the second catalyst layer 3 is applied so as to overlap the inner peripheral edge of the second frame body 7. The second catalyst layer 3 is applied such that the outer peripheral edge of the second frame 7 remains in a rectangular ring shape. The second gas diffusion layer 5 is arranged so as to overlap a part of the main surface of the second catalyst layer 3 and the outer peripheral edge of the second catalyst layer 3 remains in a rectangular ring shape.

  The membrane-electrode assembly 10 is formed by hot-pressing the one arranged as described above.

  Next, the first gas seal member 11 is disposed so as to overlap the outer edge of the first catalyst layer 2 and the outer peripheral edge of the first frame body 6. In addition, the second gas seal member 13 is disposed so as to overlap the outer edge of the second catalyst layer 3 and the outer peripheral edge of the second frame body 7.

  Then, as shown in FIG. 1B, the membrane-electrode assembly 10, the first gas seal member 11 and the second gas seal member 13, the first separator 15 and the second separator 17 are laminated and fastened. By doing so, the polymer electrolyte fuel cell 100 is manufactured. Since one polymer electrolyte fuel cell (cell) has a small electromotive force, it is preferable that a plurality of polymer electrolyte fuel cells (cells) are stacked and fastened to form a cell stack.

  When the polymer electrolyte fuel cell 100 is fastened, the outer peripheral edge portions of the first catalyst layer 2 and the second catalyst layer 3 are respectively connected to the inner peripheral edge portions of the first frame body 6 and the second frame body 7. It is deformed along a step formed between the polymer electrolyte membrane 1 and a step on the inner peripheral side is formed. The steps on the inner peripheral side are absorbed by the first gas diffusion layer 4 and the second gas diffusion layer 5, respectively. Further, a step on the outer peripheral side is formed between the outer peripheral edge of the first catalyst layer 2 and the inner peripheral edge of the first frame 6, and this step is absorbed by the first seal member 11. A step on the outer peripheral side is formed between the outer peripheral edge of the second catalyst layer 3 and the inner peripheral edge of the second frame 7, and this step is absorbed by the second seal member 13.

  In the membrane-electrode assembly 10 and the polymer electrolyte fuel cell 100 of the present embodiment, the first gas diffusion electrode 8 is configured to include the first gas diffusion layer 4 and the first catalyst layer 2, and the first catalyst. Since the entire outer peripheral edge of the layer 2 protrudes beyond the first gas diffusion layer 4, the combustion reaction occurs exclusively at the entire outer peripheral edge of the first catalyst layer 2, unlike the configuration of Patent Document 1. For this reason, the fuel reaction heat described above can be dispersed over the entire outer peripheral edge of the first catalyst layer 2 protruding outside. Therefore, thermal damage of the polymer electrolyte membrane 1 due to the influence of combustion reaction heat can be suppressed. Furthermore, the configuration of the second gas diffusion electrode 9 includes the second gas diffusion layer 5 and the second catalyst layer 3, and the entire outer peripheral edge of the second catalyst layer 3 is located outside the second gas diffusion layer 5. Because of the protrusion, unlike the configuration of Patent Document 1, the combustion reaction occurs exclusively in the entire outer peripheral edge of the second catalyst layer 3. For this reason, the fuel reaction heat described above can be dispersed in the entire outer peripheral edge of the second catalyst layer 3 protruding outside. Therefore, thermal damage of the polymer electrolyte membrane 1 due to the influence of combustion reaction heat can be suppressed.

  Further, when the outer peripheral edge portion of the first catalyst layer 2 is sandwiched between the first gas seal member 11 and the first frame body 6, it becomes easy to manufacture the membrane-electrode assembly 10 by being laminated. Furthermore, when the outer peripheral edge portion of the second catalyst layer 3 is sandwiched between the second gas seal member 13 and the second frame body 7, it becomes easy to manufacture the membrane-electrode assembly 10 by being laminated.

  Further, in the membrane-electrode assembly 10 of the present embodiment, the back surface (the surface on the polymer electrolyte membrane 1 side) of the outer peripheral edge of the first catalyst layer 2 that protrudes outside the first catalyst layer 2 is the first frame. The first gas seal member 11 is disposed on the outer peripheral edge of the first catalyst layer 2 that is covered with the body 6 and protrudes outward from the first catalyst layer 2. Therefore, unlike the configuration of Patent Document 1, the membrane-electrode assembly 10 of the present embodiment has no gap between the first gas diffusion electrode 8 and the first gas seal member 11. By disposing the first frame 6 between the outer peripheral edge of the polymer electrolyte membrane 1 and the outer peripheral edge of the first catalyst layer 2 as described above, the outer peripheral edge of the polymer electrolyte membrane 1 due to the heat of combustion reaction. It is possible to prevent damage to the part.

  Similarly, in the membrane-electrode assembly 10 of the present embodiment, the back surface (surface on the polymer electrolyte membrane 1 side) of the outer peripheral edge of the second catalyst layer 3 protruding from the second catalyst layer 3 is the second. A second gas seal member 13 is disposed on the outer peripheral edge of the second catalyst layer 3 that is covered with the frame body 7 and protrudes outward from the second catalyst layer 3. Therefore, unlike the configuration of Patent Document 1, the membrane-electrode assembly 10 of this embodiment has no gap between the second gas diffusion electrode 9 and the second gas seal member 13. By disposing the second frame 7 between the outer peripheral edge of the polymer electrolyte membrane 1 and the outer peripheral edge of the second catalyst layer 3 as described above, the outer peripheral edge of the polymer electrolyte membrane 1 due to combustion reaction heat. It is possible to prevent damage to the part.

  Further, since the first frame 6 and the first catalyst layer 2 are interposed between the first gas diffusion layer 4 and the first gas seal member 11 and the polymer electrolyte membrane 1, the first gas diffusion layer The outer end of 4 and the inner end of the first gas seal member 11 are prevented from damaging the polymer electrolyte membrane 1. In addition, since the second frame 7 and the second catalyst layer 3 are interposed between the second gas diffusion layer 5 and the second gas seal member 13 and the polymer electrolyte membrane 1, the second gas diffusion layer The outer end of 5 and the inner end of the second gas seal member 13 are prevented from damaging the polymer electrolyte membrane 1. Thereby, when the membrane-electrode assembly 10 is fastened together with the separators 15 and 17, damage to the polymer electrolyte membrane 1 due to mechanical stress is further suppressed.

[First Modification] (Modification of the First Embodiment)
FIG. 2 is a cross-sectional view showing a configuration of a first modification of the membrane-electrode assembly of the present invention and a polymer electrolyte fuel cell including the membrane-electrode assembly, wherein (a) assembles the polymer electrolyte fuel cell. The previous cross-sectional view, (b) is a cross-sectional view after assembling the polymer electrolyte fuel cell.

  In the first embodiment, the frame is disposed on both the first gas diffusion electrode 8 side and the second gas diffusion electrode 9 side. However, in the present modification, the first gas diffusion electrode 8 side and the second gas diffusion electrode 8 side are arranged. The frame 6 is disposed on one side of the gas diffusion electrode 9 side. In this case, the gas diffusion electrode on which the frame body 6 is disposed is preferably an anode. That is, it is preferable that the frame 6 is disposed on the anode side. Other configurations are the same as those of the membrane-electrode assembly of the first embodiment. In addition, the manufacturing method of the membrane-electrode assembly 10 and the polymer electrolyte fuel cell 100 is the same as that in the first embodiment.

  With such a configuration, damage to the polymer electrolyte membrane 1 is further suppressed when the polymer electrolyte fuel cell 100 is stopped. Further, when the anode side is air-bleeded, damage to the polymer electrolyte membrane 1 is further suppressed. The reason will be described below.

  First, the case where the polymer electrolyte fuel cell 100 is stopped will be described.

  When the polymer electrolyte fuel cell 100 is stopped, when purging is not performed, the fuel gas is sealed on the anode side and the oxidant gas is sealed on the cathode side. In this case, even when the polymer electrolyte fuel cell 100 is stopped, the fuel gas and the oxidant gas that have permeated the polymer electrolyte membrane 1 cause a combustion reaction, and the inside of the polymer electrolyte fuel cell 100 has a negative pressure. become. On the other hand, when the polymer electrolyte fuel cell 100 is stopped, the anode side and the cathode side may be purged with a raw material gas (for example, city gas before being reformed into fuel gas). In this case, the inside of the polymer electrolyte fuel cell 100 becomes a negative pressure due to the temperature drop after the polymer electrolyte fuel cell 100 is stopped. Then, regardless of whether the polymer electrolyte fuel cell 100 is purged or not, when the polymer electrolyte fuel cell 100 is stopped, air enters the polymer electrolyte fuel cell 100 from the outside. When the polymer electrolyte fuel cell 100 is started in this state, the air that has entered the anode side and the supplied fuel gas cause a combustion reaction. Therefore, if it is set as the above structures, the damage of the polymer electrolyte membrane 1 by the combustion reaction of the air and fuel gas which invaded at the time of the stop of the polymer electrolyte fuel cell 100 can be suppressed.

  Next, the case where air bleeding is performed on the anode side will be described.

  Air bleeding refers to mixing a small amount of air or the like into the fuel gas supplied to the anode side. If it does in this way, the mixed air and fuel gas will raise | generate a combustion reaction. Therefore, if it is set as the above structures, the damage of the polymer electrolyte membrane 1 by the combustion reaction of the air and fuel gas by an air bleed can be suppressed.

(Second Embodiment)
FIG. 3 is a cross-sectional view showing a configuration of a membrane-electrode assembly according to a second embodiment of the present invention and a polymer electrolyte fuel cell having the same, wherein (a) assembles the polymer electrolyte fuel cell. The previous cross-sectional view, (b) is a cross-sectional view after assembling the polymer electrolyte fuel cell. Hereinafter, the membrane-electrode assembly and the polymer electrolyte fuel cell of the present embodiment will be described with reference to FIG.

  In the membrane-electrode assembly 10 according to the first embodiment described above, the first gas seal member 11 and the first gas diffusion layer 4 and the second gas seal member 13 have the inner periphery and the first periphery. Between the two gas diffusion layers 5, gaps 21 and 23 having predetermined intervals were respectively provided. In the membrane-electrode assembly 10 of the present embodiment, the second gas diffusion is performed between the inner peripheral edge of the first gas seal member 11 and the first gas diffusion layer 4 and between the inner peripheral edge of the second gas seal member 13. There is no gap between the layer 5. That is, the inner peripheral edge portion of the first gas seal member 11 and the outer edge of the first gas diffusion layer 4 are in contact with each other. Further, the inner peripheral edge portion of the second gas seal member 13 and the outer edge of the second gas diffusion layer 5 are in contact with each other. Other configurations are the same as those of the membrane-electrode assembly of the first embodiment. The manufacturing method of the membrane-electrode assembly 10 and the polymer electrolyte fuel cell 100 is the same as in the case of the first embodiment.

    In addition, when manufacturing the membrane-electrode assembly 10 and the polymer electrolyte fuel cell 100 according to the present embodiment, the order in which the gas diffusion layer and the catalyst layer are disposed is changed in the manufacturing method according to the first embodiment. The second manufacturing method may be used.

  That is, the first frame 6 is disposed on one main surface of the polymer electrolyte membrane 1. On the other hand, the first gas diffusion layer 4 having a major surface wider than the inner peripheral edge of the first frame 6 is prepared separately. The first gas seal member 11 is disposed so as to be in contact with the outer periphery of the first gas diffusion layer 4. Next, the first catalyst layer 2 is applied to one main surface of the first gas diffusion layer 4 so as to overlap a part of the first gas seal member 11. Next, the main surface of the first frame 6 far from the polymer electrolyte membrane 1 and the main surface of the first catalyst layer 2 far from the first gas diffusion layer 4 are arranged to face each other.

  A second frame 7 is disposed on the other main surface of the polymer electrolyte membrane 1. On the other hand, the second gas diffusion layer 5 having a major surface wider than the inner peripheral edge of the second frame 7 is prepared separately. The second gas seal member 13 is disposed so as to be in contact with the outer periphery of the second gas diffusion layer 5. Next, the second catalyst layer 3 is applied to one main surface of the second gas diffusion layer 5 so as to overlap a part of the second gas seal member 13. Next, the main surface of the second frame 7 that is far from the polymer electrolyte membrane 1 and the main surface of the second catalyst layer 3 that is far from the second gas diffusion layer 5 are arranged to face each other.

  The membrane-electrode assembly 10 is formed by hot-pressing the one arranged as described above.

  Then, the membrane-electrode assembly 10, the first separator 15 and the second separator 17 are stacked and fastened to manufacture the polymer electrolyte fuel cell 100.

  Even with such a configuration, the same effects as those of the membrane-electrode assembly 10 and the polymer electrolyte fuel cell 100 of the first embodiment described above can be obtained.

  Furthermore, since the membrane-electrode assembly 10 and the polymer electrolyte fuel cell 100 of the present embodiment are configured as described above, the first gas diffusion layer 4 and the first gas seal member 11 and the second The reaction gas is prevented from entering from between the gas diffusion layer 5 and the second gas seal member 13. Thereby, it is suppressed that the reaction gas burns and reacts on the catalyst, and the thermal damage of the polymer electrolyte membrane 1 is further less likely to occur.

[Second Modification] (Modification of the Second Embodiment)
FIG. 4 is a cross-sectional view showing a configuration of a second modification of the membrane-electrode assembly of the present invention and a polymer electrolyte fuel cell including the membrane-electrode assembly, wherein (a) assembles the polymer electrolyte fuel cell. The previous cross-sectional view, (b) is a cross-sectional view after assembling the polymer electrolyte fuel cell.

  In the membrane-electrode assembly 10 of this modification, as in the membrane-electrode assembly of the second embodiment, between the inner peripheral edge of the first gas seal member 11 and the first gas diffusion layer 4, and the first No gap is provided between the inner peripheral edge of the two gas seal member 13 and the second gas diffusion layer 5. In the membrane-electrode assembly 10 of this modification, the frame body 6 is disposed on one side of the first gas diffusion electrode 8 side and the second gas diffusion electrode 9 side. In this case, the gas diffusion electrode on which the frame body 6 is disposed is preferably an anode. That is, it is preferable that the frame 6 is disposed on the anode side. Other configurations are the same as those of the membrane-electrode assembly of the second embodiment. The manufacturing method of the membrane-electrode assembly 10 and the polymer electrolyte fuel cell 100 is the same as in the case of the first embodiment. Furthermore, the second manufacturing method described in the second embodiment can also be used.

  With such a configuration, the polymer electrolyte membrane 1 is prevented from being damaged when the polymer electrolyte fuel cell 100 is stopped. Further, when the anode side is air-bleeded, damage to the polymer electrolyte membrane 1 is suppressed.

  Further, the reaction gas is prevented from entering between the first gas diffusion layer 4 and the first gas seal member 11 and between the second gas diffusion layer 5 and the second gas seal member 13. Thereby, it is suppressed that the reaction gas burns and reacts on the catalyst, and the thermal damage of the polymer electrolyte membrane 1 is further less likely to occur.

  The membrane-electrode assembly and the polymer electrolyte fuel cell of the present invention are useful as a membrane-electrode assembly and a polymer electrolyte fuel cell capable of suppressing damage at the outer peripheral edge of the polymer electrolyte membrane.

BRIEF DESCRIPTION OF THE DRAWINGS It is sectional drawing which shows the structure of the membrane-electrode assembly of 1st Embodiment of this invention, and a polymer electrolyte fuel cell provided with the same, Comprising: (a) is sectional drawing before assembling a polymer electrolyte fuel cell. (B) is sectional drawing after assembling a polymer electrolyte fuel cell. It is sectional drawing which shows the structure of the 1st modification of the membrane-electrode assembly of this invention, and a polymer electrolyte fuel cell provided with the same, Comprising: (a) is sectional drawing before assembling a polymer electrolyte fuel cell. (B) is sectional drawing after assembling a polymer electrolyte fuel cell. It is sectional drawing which shows the structure of the membrane-electrode assembly of 2nd Embodiment of this invention, and a polymer electrolyte fuel cell provided with the same, Comprising: (a) is sectional drawing before assembling a polymer electrolyte fuel cell. (B) is sectional drawing after assembling a polymer electrolyte fuel cell. It is sectional drawing which shows the structure of the 2nd modification of the membrane-electrode assembly of this invention, and a polymer electrolyte fuel cell provided with the same, Comprising: (a) is sectional drawing before assembling a polymer electrolyte fuel cell. (B) is sectional drawing after assembling a polymer electrolyte fuel cell.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Polymer electrolyte membrane 2 1st catalyst layer 3 2nd catalyst layer 4 1st gas diffusion layer 5 2nd gas diffusion layer 6 1st frame 7 2nd frame 8 1st gas diffusion electrode 9 2nd gas diffusion electrode 10 Membrane-Electrode Assembly 11 First Gas Seal Member 13 Second Gas Seal Member 15 First Separator 15a Reaction Gas Channel 17 Second Separator 17a Reaction Gas Channels 21, 23 Gap 100 Polymer Electrolyte Fuel Cell

Claims (12)

The first gas diffusion layer having gas diffusivity and the first gas diffusion layer are laminated to each other and have a main surface having a larger area than the main surface of the first gas diffusion layer, A first gas diffusion electrode having a plate shape including a first catalyst layer disposed so as to protrude outward from the first gas diffusion layer;
A flat plate-like second gas diffusion electrode disposed opposite to the first gas diffusion electrode;
A polymer electrolyte membrane disposed between the first catalyst layer and the second gas diffusion electrode and having a principal surface with an area equal to or greater than the principal surface of the first catalyst layer;
The outer periphery of the main surface of the polymer electrolyte membrane on the first catalyst layer side extends along the outer periphery, and the inner periphery thereof is the outer periphery of the polymer electrolyte membrane and the first catalyst layer. A frame-shaped first frame disposed so as to be inserted between
A frame shape that is arranged so that the outer peripheral edge of the first catalyst layer is sandwiched between the first frame and the first gas diffusion layer so as not to overlap the first gas diffusion layer. A first gas seal member of
A membrane-electrode assembly. A frame-shaped second gas seal member further disposed around the second gas diffusion electrode so as to face the first gas seal member;
The membrane-electrode assembly according to claim 1. The second gas diffusion electrode is configured to include a second gas diffusion layer having gas diffusivity, and a second catalyst layer disposed between the second gas diffusion layer and the polymer electrolyte membrane. And
When viewed from the thickness direction of the second catalyst layer, the outer edge of the second catalyst layer is located between the inner edge and the outer edge of the first frame,
The membrane-electrode assembly according to claim 1.   The second catalyst layer has a major surface that is larger than the major surface of the second gas diffusion layer, and is arranged so that an outer peripheral edge thereof protrudes outside the second gas diffusion layer. The membrane-electrode assembly according to claim 3. The outer periphery of the main surface of the polymer electrolyte membrane on the second catalyst layer side extends along the outer periphery, and the inner periphery thereof is the outer periphery of the polymer electrolyte membrane and the second catalyst layer. A frame-shaped second frame arranged so as to be inserted between
A frame shape sandwiched between an outer peripheral edge portion of the second catalyst layer and the second frame body and arranged around the second gas diffusion layer so as not to overlap the second gas diffusion layer. A second gas seal member of
The membrane-electrode assembly according to claim 4, further comprising:   The membrane-electrode assembly according to claim 1, wherein the first gas diffusion electrode is an anode.   7. The membrane-electrode junction according to claim 1, wherein an outer peripheral edge of the polymer electrolyte membrane protrudes outside the first catalyst layer and the second gas diffusion electrode. body.   The membrane-electrode assembly according to any one of claims 1 to 7, wherein a gap is provided between an outer edge of the first gas diffusion layer and an inner edge of the first gas seal member.   The membrane-electrode assembly according to any one of claims 2 to 8, wherein a gap is provided between an outer edge of the second gas diffusion layer and an inner edge of the second gas seal member.   The membrane-electrode assembly according to any one of claims 1 to 7, wherein an outer edge of the first gas diffusion layer and an inner edge of the first gas seal member are in contact with each other so as not to overlap each other.   The membrane-electrode assembly according to any one of claims 2 to 8, wherein an outer edge of the second gas diffusion layer and an inner edge of the second gas seal member are in contact with each other so as not to overlap each other. The membrane-electrode assembly according to any one of claims 1 to 11,
A pair of separators disposed opposite to each other so as to sandwich the membrane-electrode assembly, and having a reaction gas flow path for supplying a reaction gas to the membrane-electrode assembly;
A polymer electrolyte fuel cell.

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