JP5825241B2 - Fuel cell and fuel cell manufacturing method - Google Patents

Description

  The present invention relates to a fuel cell and a method for manufacturing the fuel cell.

  A fuel cell includes a pair of electrode layers sandwiching an electrolyte membrane. A fuel gas channel for use in an electrochemical reaction is formed on one electrode layer, and an electric electrode is formed on the other electrode layer. An oxidizing gas flow path is provided for chemical reaction. In such a fuel cell, in general, a gas seal member (gasket) is provided on the outer periphery of the electrolyte membrane in order to suppress cross leak between the fuel gas and the oxidizing gas. In general, the fuel cell further includes a gas diffusion layer on the electrode layer. As one of such fuel cells, a fuel cell is known in which a gas diffusion layer disposed on one electrode is formed smaller than a gas diffusion layer and an electrolyte membrane disposed on the other electrode layer. In this way, even if the sizes of the pair of gas diffusion layers are different from each other, by providing a gasket in contact with the outer periphery of the electrolyte membrane and the outer periphery of each gas diffusion layer, cross-leakage of fuel gas and oxidizing gas can be suppressed. (For example, refer to Patent Document 1).

Japanese Patent Laid-Open No. 2007-066766

  When providing gaskets in contact with the outer periphery of both gas diffusion layers having different sizes as described above, the portion of the gasket that contacts the smaller gas diffusion layer is on the outer surface of the larger gasket and the electrolyte membrane. Will be provided. When such a gasket is provided so as to be in contact with the outer periphery of the smaller gas diffusion layer, actually, for example, due to the accuracy of formation of the gas diffusion layer or gasket, the smaller gas diffusion layer There may be a gap between the outer periphery and the gasket.

  Thus, when a gap exists between the outer periphery of the gas diffusion layer and the gasket, the electrolyte membrane or the electrode layer formed on the electrolyte membrane is exposed in this gap. In a polymer electrolyte fuel cell, for example, when the fuel cell repeats power generation and stoppage, the state of the electrolyte membrane changes between a wet state and a dry state. As a result, the electrolyte membrane may be deformed in the plane direction, and the electrolyte membrane may buckle and be damaged in the gap where the electrolyte membrane is exposed. Such damage to the electrolyte membrane is undesirable because it can cause cross leakage of fuel gas and oxidant gas. Therefore, it has been desired to suppress damage to the electrolyte membrane even when the electrolyte membrane changes between a wet state and a dry state. In addition, in a fuel cell, it has been desired to reduce the number of parts and simplify the manufacturing process, including a structure for gas sealing.

SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples (1) to (4) .
[Form 1]
A membrane-electrode assembly in which electrodes are formed on both sides of an electrolyte membrane composed of a polymer electrolyte that swells by absorbing moisture and contracts by drying, and contacts each surface of the membrane-electrode assembly A fuel cell comprising: a first gas diffusion layer and a first gas diffusion layer disposed on the membrane-electrode assembly and configured by a conductive porous body; and an outer periphery of the first gas diffusion layer. At least a portion and the outer periphery of the second gas diffusion layer and the membrane-electrode assembly do not overlap in the stacking direction of the first and second gas diffusion layers. The at least part of the outer periphery is disposed closer to the center of the first and second gas diffusion layers than the outer periphery of the second gas diffusion layer and the membrane-electrode assembly, and the fuel cell Is provided with the first gas diffusion layer in the membrane-electrode assembly. And in contact with the surface of the membrane-electrode assembly on which the first gas diffusion layer is provided in the vicinity of at least a part of the outer periphery of the first gas diffusion layer. A part of the wall surface is constituted by a seal member provided apart from the outer periphery of the gas diffusion layer, the at least part of the outer periphery of the first gas diffusion layer, the seal member, and the membrane-electrode assembly. And a protective layer containing a polymer electrolyte that is provided so as to close at least a part of the gap, swells by absorbing moisture, and shrinks by drying.
According to the fuel cell of this aspect, since the protective layer is formed in the gap between at least a part of the outer periphery of the first gas diffusion layer and the seal member, the electrolyte membrane swells during power generation of the fuel cell. Even in this case, the electrolyte membrane can be prevented from buckling in the gap. Since the buckling of the electrolyte membrane can be suppressed, the electrolyte membrane can be prevented from being damaged, and the cross leak between the fuel gas and the oxidizing gas caused by the damage to the electrolyte membrane can be suppressed.

(1) According to one aspect of the present invention, a membrane-electrode assembly in which electrodes are formed on both surfaces of an electrolyte membrane, and the membrane-electrode assembly on the membrane-electrode assembly so as to contact each surface of the membrane-electrode assembly There is provided a fuel cell comprising first and second gas diffusion layers disposed on the surface and configured by a conductive porous body. In this fuel cell, at least a part of the outer periphery of the first gas diffusion layer and the outer periphery of the second gas diffusion layer and the membrane-electrode assembly are the same as those of the first and second gas diffusion layers. The at least part of the outer periphery of the first gas diffusion layer does not overlap in the stacking direction, and the first and second gases are more than the outer periphery of the second gas diffusion layer and the membrane-electrode assembly. It is arranged near the center of the diffusion layer. In the fuel cell, a sealing member provided on the surface of the membrane-electrode assembly on which the first gas diffusion layer is provided, and in the vicinity of at least a part of the outer periphery of the first gas diffusion layer And a protective layer that closes at least a part of the gap between the at least part of the outer periphery of the first gas diffusion layer and the seal member. According to the fuel cell of this aspect, since the protective layer is formed in the gap between at least a part of the outer periphery of the first gas diffusion layer and the seal member, the electrolyte membrane swells during power generation of the fuel cell. Even in this case, the electrolyte membrane can be prevented from buckling in the gap. Since the buckling of the electrolyte membrane can be suppressed, the electrolyte membrane can be prevented from being damaged, and the cross leak between the fuel gas and the oxidizing gas caused by the damage to the electrolyte membrane can be suppressed.

(2) In the fuel cell of the above aspect, the protective layer may be formed of a thermoplastic resin or a thermosetting resin. According to the fuel cell of this aspect, the protective layer formed of the thermoplastic resin or the thermosetting resin increases the thickness of the portion exposed in the gap, thereby enhancing the effect of suppressing the buckling of the electrolyte membrane. be able to.

(3) In the fuel cell of the above aspect, the protective layer may contain a polymer electrolyte. According to this type of fuel cell, the protective layer can swell or contract as the electrolyte membrane swells or contracts. Therefore, generation | occurrence | production of the stress in the interface of a membrane-electrode assembly and a protective layer can be suppressed, and durability of the laminated body of a membrane-electrode assembly and a protective layer can be improved.

(4) According to another embodiment of the present invention, a membrane-electrode assembly in which electrodes are formed on both surfaces of an electrolyte membrane, and the membrane-electrode assembly so as to contact each surface of the membrane-electrode assembly Provided is a method for manufacturing a fuel cell, comprising first and second gas diffusion layers disposed on and composed of a conductive porous body. The fuel cell manufacturing method includes: a first step of preparing the membrane-electrode assembly; at least a part of an outer periphery of the first gas diffusion layer; the second gas diffusion layer; and the membrane-electrode. The outer periphery of the joined body does not overlap in the stacking direction of the first and second gas diffusion layers, and the at least part of the outer periphery of the first gas diffusion layer is the second gas diffusion layer and the The membrane-electrode assembly is sandwiched between the first and second gas diffusion layers so as to be disposed closer to the center of the first and second gas diffusion layers than the outer periphery of the membrane-electrode assembly. A sealing member on the surface of the membrane-electrode assembly on which the first gas diffusion layer is provided, in the vicinity of the at least part of the outer periphery of the first gas diffusion layer; A third step of disposing; and providing the first gas diffusion layer in the membrane-electrode assembly And a fourth step of applying a softened material to at least a part of the gap between the at least part of the outer periphery of the first gas diffusion layer and the seal member; And a fifth step of curing the softened material to form a protective layer. According to the method for manufacturing a fuel cell of this aspect, the above-described fuel cell as one aspect of the present invention can be easily manufactured and the above-described effects can be obtained.

  The present invention can be realized in various forms other than those described above. For example, the present invention can be realized in a form such as a method for suppressing a gas leak in a fuel cell or a method for forming a seal structure of a gas flow path in a cell in a fuel cell. It is.

It is a cross-sectional schematic diagram showing schematic structure of a fuel cell. It is a top view which shows typically arrangement | positioning of a gas diffusion layer. It is process drawing showing the manufacturing method of a fuel cell. It is explanatory drawing showing the mode of formation of a protective layer. It is a figure for demonstrating a mode that electrolyte membrane swells and buckles. Is an explanatory view showing the relationship between the thickness t and the swelling strain ε and the minimum slit width 2a ₀ of the electrolyte membrane. It is explanatory drawing showing a part of process in the manufacturing method of a fuel cell. It is a top view which shows typically arrangement | positioning of a gas diffusion layer.

A. First embodiment:
A-1. Fuel cell configuration:
FIG. 1 is a schematic cross-sectional view showing a schematic configuration of a fuel cell as a first embodiment of the present invention. Although FIG. 1 shows the structure of a single cell 10 that is a power generation module, the fuel cell has a stack structure in which a plurality of single cells 10 shown in FIG. 1 are stacked.

  The unit cell 10 includes an electrolyte membrane 20, an anode 21 and a cathode 22 that are electrodes formed on each surface of the electrolyte membrane 20, and a gas diffusion layer 23 that sandwiches the electrolyte membrane 20 on which the electrode is formed from both sides, 24, gas separators 25 and 26 disposed further outside the gas diffusion layers 23 and 24, a seal member 30 disposed near the outer periphery of the gas diffusion layer 24, and a protective layer 32. FIG. 1 shows a state of an area close to the outer periphery of a single cell 10 in which the above-described members are stacked.

  The fuel cell according to this embodiment is a solid polymer fuel cell, and the electrolyte membrane 20 includes a proton conductive ion exchange membrane formed of a solid polymer material, for example, a fluororesin having perfluorocarbon sulfonic acid. And exhibits good electrical conductivity in the wet state. The anode 21 and the cathode 22 include, for example, platinum or a platinum alloy as a catalyst. More specifically, the anode 21 and the cathode 22 include carbon particles carrying the catalyst and an electrolyte similar to the polymer electrolyte that constitutes the electrolyte membrane 20. In order to form the anode 21 and the cathode 22, for example, carbon particles carrying platinum or an alloy made of platinum and other metals are produced, and the carbon particles carrying the catalyst are dispersed in a suitable organic solvent, and the electrolyte is then prepared. An appropriate amount of solution may be added to prepare a catalyst ink. By applying this catalyst ink onto the electrolyte membrane 20 by a method such as screen printing, the anode 21 and the cathode 22 can be formed. The electrolyte membrane 20, the anode 21, and the cathode 22 constitute an MEA (membrane-electrode assembly) 29.

  The gas diffusion layers 23 and 24 can be formed of a conductive member having gas permeability, such as carbon paper or carbon cloth, metal mesh, or foam metal. The gas diffusion layers 23 and 24 are both formed as flat plate members. By providing the gas diffusion layers 23 and 24, the gas supply efficiency to the electrodes can be improved, the current collection between the gas separators 25 and 26 and the electrodes can be improved, and the electrolyte membrane 20 can be protected. it can.

  In the present embodiment, in each of the gas diffusion layers 23 and 24, water repellent layers 27 and 28 are provided on the surface in contact with the MEA 29. The water repellent layers 27 and 28 include carbon particles and a water repellent material such as a fluororesin. Such water-repellent layers 27 and 28 are formed by applying water-repellent ink, which is a mixed solution containing carbon particles and a water-repellent substance, to the surfaces of the conductive members constituting the gas diffusion layers 23 and 24, and drying and It is formed by firing. The water-repellent layers 27 and 28 provided between the electrode and the gas diffusion layers 23 and 24 have a function of repelling liquid water and pushing it back to the electrode side. Thus, the electrolyte membrane 20 is pushed back by pushing the liquid water back. Suppressing moisture shortage. Further, by repelling the liquid water, the pores of the gas diffusion layers 23 and 24 are suppressed from being blocked by the liquid water, and the inhibition of the gas flow due to the blockage of the pores is suppressed.

  In this embodiment, the water-repellent ink is applied on the gas diffusion layers 23 and 24 to form the water-repellent layers 27 and 28. However, the water-repellent ink is applied on the MEA 29 to form the water-repellent layers 27 and 28. It may be formed. Further, the water-repellent ink is not applied only to one side of the gas diffusion layers 23 and 24, but the entire gas diffusion layers 23 and 24 are impregnated with the water-repellent ink so that the entire gas diffusion layers 23 and 24 are covered with the water-repellent layer. 27 and 28 may be used. Alternatively, the water-repellent layers 27 and 28 may be formed by applying water-repellent ink that does not contain carbon particles on the gas diffusion layers 23 and 24. Instead of water-repellent ink containing carbon particles and water-repellent substance, water-repellent powder prepared by mixing a mixture of carbon particles and water-repellent substance into powder, or a mixture of carbon particles and water-repellent substance in sheet form You may use the water-repellent sheet | seat shape | molded in. That is, the water repellent powder 27 and the water repellent sheet may be disposed on the gas diffusion layers 23 and 24 or the MEA 29 to form the water repellent layers 27 and 28. Alternatively, the water repellent layers 27 and 28 may not be provided.

  FIG. 2 is a plan view schematically showing the arrangement of the gas diffusion layers 23 and 24. In the present embodiment, the gas diffusion layer 23 and the gas diffusion layer 24 have different sizes, and the gas diffusion layer 24 is formed smaller. Specifically, the gas diffusion layer 24 is formed smaller than the gas diffusion layer 23 and the electrolyte membrane 20 (MEA 29), and the outer periphery of the gas diffusion layer 24 is larger than the outer periphery of the gas diffusion layer 23 and the electrolyte membrane 20. The gas diffusion layers 23 and 24 are disposed near the center. In the present embodiment, the gas diffusion layer 24 corresponds to a “first gas diffusion layer” in the claims, and the gas diffusion layer 23 corresponds to a “second gas diffusion layer” in the claims. .

  The gas separators 25 and 26 are formed of a gas-impermeable conductive member, for example, a carbon-made member such as dense carbon that has been made to be gas-impermeable by compressing carbon, or a metal member such as press-molded stainless steel. ing. In the gas separators 25 and 26, the surface facing the catalyst electrode layer (the anode 21 or the cathode 22) is formed with an uneven shape that forms a plurality of parallel flow channel grooves 41 and 42 through which the reaction gas flows. The channel groove 41 forms an in-cell fuel gas channel through which the fuel gas flows, between the channel groove 41 and the gas diffusion layer 23. The channel groove 42 forms an in-cell oxidizing gas channel through which the oxidizing gas flows, between the channel groove 42 and the gas diffusion layer 24. The gas separators 25 and 26 are in contact with the gas diffusion layers 23 and 24 at the tops of the protrusions protruding toward the gas diffusion layer in the uneven shape. The channel grooves 41 and 42 of the gas separators 25 and 26 are formed over the entire region overlapping the gas diffusion layer 24 in the stacking direction. Although the electrochemical reaction can proceed at the anode 21 and the cathode 22, the electrochemical reaction substantially proceeds in a region where the fuel gas is supplied to the anode 21 and a region where the oxidizing gas is supplied to the cathode 22. Is a region where and overlap. Therefore, on the electrode surface, it can be considered that the electrochemical reaction substantially proceeds in a region overlapping with the gas diffusion layer 24 formed smaller in the stacking direction. Hereinafter, the region overlapping the gas diffusion layer 24 in the stacking direction is also referred to as a power generation region (see FIG. 1). In the present embodiment, the cathode 22 includes a power generation region and is provided over a region slightly larger than the power generation region. The anode 21 includes a power generation region and is provided over a region wider than the cathode 22 (see FIG. 1). However, the anode 21 and the cathode 22 may be provided in a region overlapping with the power generation region.

  The seal member 30 is a thin plate-like member disposed in the vicinity of the outer periphery of the gas diffusion layer 24 on the surface of the MEA 29 on which the gas diffusion layer 24 is provided. The sealing member 30 can be formed of an insulating material, for example, a resin having a melting point higher than the operating temperature of the fuel cell and stable in the internal environment of the fuel cell. The gas separators 25 and 26 described above have flat portions without unevenness closer to the outer periphery than the region overlapping the power generation region in the stacking direction. The seal member 30 is in contact with the flat portion of the gas separator 26 and seals the in-cell oxidizing gas flow path (see FIG. 1). The seal member 30 of this embodiment has substantially the same thickness as the gas diffusion layer 24 as shown in FIG. 1, but the thickness of the seal member 30 depends on the constituent material of the seal member 30 and the shape of the gas separator 26. Or, it may be appropriately set according to the magnitude of the fastening pressure in the stacking direction applied to the stack of single cells 10 when the fuel cell is assembled. That is, the thickness of the seal member 30 may be set so that the surface pressure applied to the power generation region becomes a desired pressure when the fuel cell is assembled and the entire laminate is fastened.

  The protective layer 32 is provided on the MEA 29 exposed through the gap so as to close the gap between the outer periphery of the gas diffusion layer 24 and the seal member 30. The protective layer 32 of the present embodiment is composed of the same type of polymer electrolyte as the polymer electrolyte that constitutes the electrolyte membrane 20.

  As will be described later, the protective layer 32 is formed by applying a softened resin material on the MEA 29. As the resin material in the softened state, for example, a resin-containing liquid in which a resin for forming the protective layer 32 is dissolved or dispersed in a solvent such as water or alcohol can be used. When using a resin-containing liquid, the solvent is vaporized and removed during the manufacturing process, as will be described later. Therefore, a solvent that is easy to remove by heating and does not react with other members constituting the fuel cell is used. The resin-containing liquid may be adjusted. A method for forming the protective layer 32 with application of the softened resin material will be described in detail later.

  An inter-cell refrigerant flow path is further formed inside the fuel cell (not shown). FIG. 1 shows a single cell 10. When a fuel cell is formed by stacking such single cells 10, for example, an inter-cell refrigerant flow is provided between gas separators provided in adjacent single cells 10. What is necessary is just to form a path.

  Furthermore, a plurality of flow paths that penetrate the fuel cell in the stacking direction are formed inside the fuel cell. Specifically, a gas manifold for supplying / discharging the reaction gas to / from each cell and a refrigerant manifold for supplying / discharging the refrigerant to / from the refrigerant flow path described above are formed. In the present embodiment, the manifolds described above are formed by the holes provided in the gas separators 25 and 26 at positions closer to the outer periphery than the region shown in FIG.

  As described above, the seal member 30 is disposed in the vicinity of the outer periphery of the gas diffusion layer 24, but the outer periphery of the gas diffusion layer 23 formed larger than the gas diffusion layer 24, the outer periphery of the MEA 29, and the seal member 30. An adhesive is applied to the outer periphery of the substrate. Thereby, the sealing property of the in-cell fuel gas channel is ensured together with the in-cell oxidizing gas channel. As the adhesive, for example, an epoxy adhesive, a silicone adhesive, or a silicone RTV rubber can be used.

  The range in which the adhesive is applied and the range in which the seal member 30 is disposed are appropriately set according to the positions of the holes provided in the gas separators 25 and 26 in order to form the manifold described above. For example, when the sealing member 30 is provided so as to surround the power generation region along the outer periphery of the gas diffusion layer 24, the region that connects the power generation region and the hole that forms the gas manifold for supplying and discharging the oxidizing gas The shape of the seal member 30 may be determined so that the seal member 30 is not disposed. The shape of the region to which the adhesive is applied and the shape of the seal member 30 are such that the sealing property of the in-cell oxidizing gas passage and the in-cell fuel gas passage is ensured, and the gas manifold corresponding to the in-cell gas passage. Any shape is acceptable as long as the gas flow between the two is not hindered.

A-2. Method for forming protective layer:
Below, the manufacturing method of the fuel cell of this embodiment is demonstrated centering on the formation method of the protective layer 32. FIG. FIG. 3 is a process diagram showing the method of manufacturing the fuel cell of the present embodiment. FIG. 4 is an explanatory diagram showing a state in which the protective layer 32 is formed during the manufacturing process of the fuel cell.

  When manufacturing a fuel cell, first, the MEA 29 is prepared (step S100). Thereafter, the gas diffusion layers 23 and 24 are disposed and stacked on each surface of the MEA 29 (step S110). In the present embodiment, the water-repellent layers 27 and 28 are formed on the gas diffusion layers 23 and 24 before the gas diffusion layers 23 and 24 are stacked. When laminating the gas diffusion layers 23 and 24 and the MEA 29, the whole may be integrated by, for example, hot pressing.

  Thereafter, the seal member 30 is disposed on the MEA 29 and in the vicinity of the outer peripheral portion of the gas diffusion layer 24 (step S120). When the sealing member 30 is disposed, the sealing member 30 and the MEA 29 may be bonded using an adhesive. Alternatively, the seal member 30 may be fixed to the MEA 29 by pressurization or pressurization with heating.

  The shape of the gas diffusion layer 24 is set in advance as a shape corresponding to the power generation region, and the shape of the seal member 30 is also set in advance so as to be disposed at a position very close to the outer periphery of the gas diffusion layer 24. Yes. However, the accuracy in producing the gas diffusion layer 24 and the seal member 30 is limited. Further, there is a limit to the accuracy of the operation of disposing the seal member 30 near the outer periphery of the gas diffusion layer 24. Here, when the seal member 30 is disposed, if the end portion of the seal member 30 overlaps the outer peripheral portion of the gas diffusion layer 24, the thickness of the overlapped portion increases. It is difficult to ensure a good sealing performance. Therefore, the shapes of the gas diffusion layer 24 and the seal member 30 are set so that the seal member 30 does not overlap the gas diffusion layer 24 in consideration of the accuracy of the operation of disposing the seal member 30. As a result, after step S120, a gap of about several hundred μm is generated between the outer periphery of the gas diffusion layer 24 and the seal member 30.

  Thereafter, in step S130 and step S140, the protective layer 32 is formed in the gap. First, as shown in FIG. 4A, a softened resin material is applied to the gap 35 between the gas diffusion layer 24 and the seal member 30 (step S130). As described above, in the present embodiment, the protective layer 32 is composed of a polymer electrolyte of the same type as the polymer electrolyte constituting the electrolyte membrane 20. FIG. 4 shows a state where a resin-containing liquid 52 in which such a polymer electrolyte is dissolved or dispersed in a solvent such as water or alcohol is applied.

  In this embodiment, in order to apply the resin-containing liquid 52, a discharge device having a nozzle 50 provided with a heater is used. The diameter of the nozzle 50 is desirably smaller than the width of the gap 35, and can be, for example, about 100 μm. By heating the tip of the nozzle 50 using a heater, the resin-containing liquid 52 having a sufficiently reduced viscosity can be applied to the gap 35. The degree of heating of the resin-containing liquid 52 is not limited as long as the viscosity of the resin-containing liquid 52 can be sufficiently suppressed, and can be, for example, 50 ° C. or higher. Any temperature range that does not cause decomposition or damage is acceptable. By sufficiently suppressing the viscosity of the resin-containing liquid 52, the resin-containing liquid 52 discharged from the nozzle 50 can spread quickly in the gap 35.

  By applying the resin-containing liquid 52 as described above, the resin-containing liquid 52 spreads in the gap 35 and closes the gap 35. It is desirable that the amount of the resin-containing liquid 52 applied is larger as long as the resin-containing liquid 52 does not overflow from the gap 35. FIG. 4B shows a state in which the resin-containing liquid 52 fills the gap 35 and forms the resin-containing liquid layer 54 when the gas diffusion layer 24 and the sealing member 30 have the same thickness.

  When applying the resin-containing liquid 52, a position sensor may be provided in the discharge device having the nozzle 50. The position sensor detects the end of the seal member 30 and / or the position of the outer periphery of the gas diffusion layer 24 while detecting the position of the end of the seal member 30 or the outer periphery of the gas diffusion layer 24. May be applied. Thereby, the precision of the operation | movement which apply | coats the resin containing liquid 52 in the clearance gap 35 is securable. The position sensor can employ various configurations. For example, an imaging device such as a CCD camera may be provided, and the position of the end of the seal member 30 and / or the outer periphery of the gas diffusion layer 24 may be detected by image processing using image data. Or you may comprise the said position sensor by the infrared sensor which detects a position using reflection of infrared rays.

  Next, the protective layer 32 is formed from the resin-containing liquid layer 54 (step S140). In the present embodiment, the protective layer 32 made of a polymer electrolyte is formed by heating the resin-containing liquid layer 54 to vaporize and remove the solvent. The resin-containing liquid layer 54 can be heated, for example, by placing the entire structure shown in FIG. 4B on a hot plate heated to about 120 to 150 ° C. Alternatively, if the resin-containing liquid 52 is heated to about 50 to 120 ° C. by heating the nozzle 50 during the application in step S130, the solvent can be vaporized simultaneously with the application by the heat applied to the resin-containing liquid 52. . In this case, it is not necessary to separately perform a heating process using a special heating device or the like in order to vaporize the solvent, and the protective layer 32 is formed by leaving the resin-containing liquid layer 54 to dry for a while after the application. Can be formed.

  FIG. 4C shows a state in which the solvent is evaporated in step S140 to form the protective layer 32. FIG. When the solvent is volatilized and removed, the thickness of the resin-containing liquid layer 54 is reduced. For example, when the resin-containing liquid layer 54 is formed using the resin-containing liquid 52 with a volume concentration of the polymer electrolyte of 50%, the solvent is volatilized from the resin-containing liquid layer 54, thereby A protective layer 32 having a thickness about half the thickness is formed.

  After the formation of the protective layer 32, the laminated body on which the protective layer 32 is formed and the gas separators 25 and 26 are laminated, and at least a predetermined separator on the outer periphery of the laminated body on the gas separator. The single cell 10 is completed by applying an adhesive to the position (step S150).

A-3. About film thickness and buckling caused by gaps:
In this embodiment, by providing the protective layer 32, the electrolyte membrane 20 (MEA 29) exposed in the gap 35 is prevented from buckling in the gap 35. That is, the electrolyte membrane 20 composed of the polymer electrolyte repeats moisture absorption and drying as the fuel cell repeatedly generates and stops power and the power generation state changes. The electrolyte membrane 20 swells by absorbing moisture and contracts by drying. Therefore, when the electrolyte membrane 20 swells to some extent, the electrolyte membrane 20 buckles (causes undulation) in the gap 35.

FIG. 5 is a diagram for explaining how the electrolyte membrane swells and buckles. FIG. 5A shows an initial state (state before swelling) of an electrolyte membrane similar to the electrolyte membrane 20 of the present embodiment. FIG. 5A shows that the thickness of the electrolyte membrane in the initial state is t, and the length in a specific direction parallel to the surface direction of the electrolyte membrane is l ₀ . FIG. 5B shows a state where the electrolyte membrane is swollen. FIG. 5B shows that the length in the specific direction of the electrolyte membrane is l _{1 due} to swelling. Assuming that the swelling strain when the electrolyte membrane swells is ε, ε can be expressed by the following equation (1).

  FIG. 5B shows a state in which the electrolyte membrane freely swells, but both ends of the portion exposed by the gap 35 in the electrolyte membrane 20 of the present embodiment are constrained by the gas diffusion layer 24 and the seal member 30. Is in a fixed state (fixed state). FIG. 5C shows how the electrolyte membrane with both ends restrained in this way swells. As shown in FIG. 5C, when the electrolyte membrane whose both ends are constrained swells to some extent, the electrolyte membrane buckles (causes undulation). In FIG. 5C, the distance between the undulation peaks generated in the buckled electrolyte membrane (hereinafter referred to as the buckling width) is 2a.

_Assuming that σ _mem is the swelling stress generated in the electrolyte membrane when the electrolyte membrane swells in a state where both ends are constrained as shown in FIG. 5C, σ _mem can be expressed by the following equation (2). .

（ただし、Ｅはヤング率を表わし、νはポアソン比を表わし、εは膨潤歪みを表わす。）

(Where E represents Young's modulus, ν represents Poisson's ratio, and ε represents swelling strain.)

Further, as shown in FIG. 5C, when the electrolyte membrane swells in a state where both ends are constrained, the critical stress at which the electrolyte membrane starts to buckle (when the electrolyte membrane starts to buckle, _Assuming that σ _cr is the minimum stress generated in the buckling electrolyte membrane, σ _cr can be expressed by the following equation (3) based on Euler's equation.

（ただし、Ｅはヤング率を表わし、νはポアソン比を表わし、ｔは膜厚を表わし、ａは座屈幅の半分の長さを表わす。）

(Where E represents Young's modulus, ν represents Poisson's ratio, t represents film thickness, and a represents half the buckling width.)

When the water content of the electrolyte membrane is very small, the swelling stress σ _mem of the electrolyte membrane shown in the equation (2) is smaller than the critical stress σ _{cr at} which the electrolyte membrane shown in the equation (3) starts buckling. In such a state, the electrolyte membrane does not buckle. When the water content of the electrolyte membrane increases and the degree of swelling increases with both ends of the electrolyte membrane being constrained, the swelling stress σ _mem of the electrolyte membrane gradually approaches the critical stress σ _cr . When the swelling stress σ _mem reaches the critical stress σ _cr , buckling starts to occur in the electrolyte membrane. Therefore, the electrolyte membrane in which both ends are constrained is considered to buckle when the condition shown in the following equation (4) is satisfied.

  Here, when the formulas (2) and (3) are substituted into the formula (4), the following formula (5) is derived.

（ただし、νはポアソン比を表わし、ｔは膜厚を表わし、εは膨潤歪みを表わす。）

(Where ν represents Poisson's ratio, t represents film thickness, and ε represents swelling strain.)

That is, it can be said that the buckling width 2a when the electrolyte membrane buckles is equal to or larger than the value on the right side of the equation (5). Therefore, if the minimum value of the buckling width when the electrolyte membrane buckles is 2a ₀ , the minimum value 2a ₀ of the buckling width is expressed by the following equation (6).

（ただし、νはポアソン比を表わし、ｔは膜厚を表わし、εは膨潤歪みを表わす。）

(Where ν represents Poisson's ratio, t represents film thickness, and ε represents swelling strain.)

Therefore, when both ends of the electrolyte membrane are constrained as in the fuel cell of this embodiment, the length between the constrained both ends (the width of the gap 35, the gas diffusion layer 24 and the seal member 30). ) Is considered to be buckled when the buckling width is not less than the minimum value 2a _{0 of the} buckling width. Hereinafter, the minimum value 2a ₀ of the buckling width is also referred to as a minimum slit width at which buckling of the electrolyte membrane occurs. FIG. 5D shows a state where the width of the gap 35 is 2a ₀ in the fuel cell of the present embodiment. As shown in the above equation (6), the minimum slit width 2a ₀ can be considered as a value determined by the thickness t of the electrolyte membrane and the swelling strain by ε. The thickness t of the electrolyte membrane may vary depending on the wet state of the electrolyte membrane, but in the above formula (6), the film thickness t is the thickness of the electrolyte membrane in the dry state.

FIG. 6 is an explanatory diagram showing the relationship among the thickness t of the electrolyte membrane, the swelling strain ε, and the minimum slit width 2a ₀ where buckling occurs based on the above-described equation (6). Here, the swelling strain ε is a value that varies depending on the moisture absorption state of the electrolyte membrane. The electrolyte membrane differs in the value of the swelling strain ε with respect to the amount of water absorption depending on the composition, but regardless of the composition of the electrolyte membrane, the thickness t of the electrolyte membrane, the swelling strain ε, and the minimum slit width at which buckling occurs 2a ₀ indicates the relationship shown in FIG. In the electrolyte membrane, the maximum water absorption and the maximum value of the swelling strain ε are determined according to the composition. Therefore, depending on the composition of the electrolyte membrane, unlike FIG. 6, the maximum value of the swelling strain ε may not reach 0.2.

As shown in FIG. 6, when the composition of the electrolyte membrane is constant, if the swelling strain ε is the same value, that is, if the wet state of the electrolyte membrane is the same, the greater the thickness t of the electrolyte membrane, the more buckling occurs. the value of the minimum slit width 2a ₀ occurring increases. That is, according to the fuel cell of the present embodiment, if the width of the gap 35 (distance between the gas diffusion layer 24 and the seal member 30) is constant, the electrolyte membrane 20 is seated as the thickness of the electrolyte membrane 20 increases. It can be said that it is hard to yield. Further, if the thickness of the electrolyte membrane 20 is constant, it can be said that the electrolyte membrane is more easily buckled as the width of the gap 35 (distance between the gas diffusion layer 24 and the seal member 30) is larger. In addition, as shown in FIG. 6, if the thickness t of the electrolyte membrane 20 is constant, the minimum slit width 20a decreases as the swelling strain ε increases, that is, the moisture content of the electrolyte membrane 20 increases. It can be said that bending tends to occur. In the fuel cell according to the present embodiment, as described above, the electrolyte membrane 20 is formed with electrodes on the surface to constitute the MEA 29. However, in the description based on FIG. Yes. However, in the MEA 29 including the electrodes, the same relationship as described above is established between the overall thickness, the magnitude of the swelling strain, and the minimum slit width at which buckling occurs.

  According to the fuel cell manufactured by the fuel cell manufacturing method of the present embodiment configured as described above, since the protective layer 32 is formed in the gap 35, the electrolyte membrane 20 swells during power generation of the fuel cell. Even if it does, it can suppress that the electrolyte membrane 20 buckles in the clearance gap 35. FIG. Since the buckling of the electrolyte membrane 20 can be suppressed, the damage to the electrolyte membrane 20 can be suppressed, and the cross leak between the fuel gas and the oxidizing gas due to the damage to the electrolyte membrane 20 can be suppressed.

The above-described effect of suppressing buckling of the electrolyte membrane in the present embodiment can be understood as follows. That is, by providing the protective layer 32 made of the polymer electrolyte, the thickness of the electrolyte membrane in the region where the gap 35 is formed can be substantially increased. By increasing the thickness of the electrolyte membrane in this manner, as described above, the minimum slit width 2a _{0 at} which the electrolyte membrane buckles becomes larger. As a result, the distance between the gas diffusion layer 24 and the seal member 30 is sufficiently smaller than the minimum slit width 2a ₀ in the electrolyte membrane whose thickness is increased by the protective layer 32, thereby suppressing the buckling of the electrolyte membrane. Can do.

  Here, the single cell having the configuration shown in FIG. 1 was actually assembled to generate power, and the effect of the protective layer 32 was confirmed. Specifically, an electrolyte membrane 20 (film thickness: 20 μm, swelling rate in a planar direction in a swollen state to be described later: 10%) formed of a fluororesin containing perfluorocarbon sulfonic acid, and gas diffusion with a thickness of 200 μm A single cell including the layer 24 and the seal member 30 and having a distance of 2 mm between the outer periphery of the gas diffusion layer 24 and the seal member 30 was assembled. Then, a resin-containing liquid 52 (the solvent is water and the nozzle tip temperature is 50 ° C.) containing a polymer electrolyte of the same type as the electrolyte membrane 20 at a volume concentration of 50% is applied to the gap 35 and dried to obtain a thickness. A single cell of the example in which a protective layer 32 of 100 μm was formed was produced. Therefore, in the single cell of the example, the thickness of the electrolyte in the gap 35 was 120 μm as a whole. In addition, a single cell of a comparative example in which the MEA 29 was exposed through the gap 35 without having the protective layer 32 without forming the protective layer 32 was manufactured. A treatment (dry cycle) for repeating the wet state and the dry state was added 10 times to the single cells of these examples and comparative examples. The dry / wet cycle refers to a treatment under a temperature condition of 80 ° C. for 5 minutes with 100% RH as a wet state and 5 minutes with 5% RH as a dry state. After such processing, when the gap 35 was observed using a digital microscope, no buckling occurred in the single cell of the example, but buckling occurred in the single cell of the comparative example (data Not shown).

  Moreover, according to the fuel cell of this embodiment, since the protective layer 32 is formed of the same polymer electrolyte as the electrolyte membrane 20, the protective layer 32 is separated from the electrolyte membrane 20 according to the surrounding wet state. Similarly, swelling and shrinking are repeated. Therefore, stress is unlikely to occur at the interface between the protective layer 32 and the electrolyte membrane 20, and even when the electrolyte membrane 20 repeats swelling and shrinkage, damage such as peeling at the interface between the protective layer 32 and the electrolyte membrane 20 occurs. Can be suppressed. Therefore, a decrease in the durability of the fuel cell due to the provision of the protective layer 32 can be suppressed.

  Furthermore, according to this embodiment, since the protective layer 32 is formed by applying the resin-containing liquid 52 to the gap 35, it is necessary to prepare a special member in advance for providing the protective layer 32. Absent. Therefore, an increase in the number of parts can be suppressed and the manufacturing process can be simplified.

  Further, according to the fuel cell of the present embodiment, the gas diffusion layer 24 is formed smaller than the gas diffusion layer 23, and the outer periphery of the gas diffusion layer 24 is more gas diffusion than the outer periphery of the gas diffusion layer 23 and the electrolyte membrane 20. The layers 23 and 24 are disposed near the center. That is, the outer periphery of the gas diffusion layer 23 and the outer periphery of the gas diffusion layer 24 do not overlap in the stacking direction of the gas diffusion layers 23, 24, and the outer periphery of the gas diffusion layer 23 and the gas diffusion via the outer periphery of the electrolyte membrane 20. A longer distance from the outer periphery of the layer 24 is ensured. Therefore, in order for the oxidizing gas in the in-cell oxidizing gas channel and the fuel gas in the in-cell fuel gas channel to cross-leak beyond the outer periphery of the electrolyte membrane 20, each gas has a longer distance. It is necessary to leak around. Therefore, according to the present embodiment, it is possible to enhance the effect of suppressing gas cross-leakage through the outer periphery of the electrolyte membrane 20 between the in-cell oxidizing gas channel and the in-cell fuel gas channel.

  Furthermore, according to this embodiment, since the distance between the outer periphery of the gas diffusion layer 23 and the outer periphery of the gas diffusion layer 24 is ensured longer, a short circuit between the gas diffusion layer 23 and the gas diffusion layer 24 is suppressed. The effect can be enhanced. That is, it can suppress that the conductive fibers which comprise both gas diffusion layers contact over the outer periphery of the electrolyte membrane 20, and can suppress a short circuit.

  As described above, the protective layer 32 covers the entire electrolyte membrane 20 (MEA 29) exposed in the gap 35 to prevent buckling of the electrolyte membrane 20, but the protective layer 32 is exposed in the gap 35. It is not always necessary to cover the electrolyte membrane 20 to be completely covered. That is, even if the gap 35 is not completely covered by the protective layer 32, if at least a part of the MEA 29 exposed in the gap 35 is covered by the protective layer 32, the electrolyte membrane 20 is not covered by the protective layer 32. The film thickness becomes thicker. Further, the width of the electrolyte membrane 20 exposed in the gap 35 without being covered by the protective layer 32 is reduced. Therefore, an effect of suppressing buckling of the electrolyte membrane 20 can be obtained.

B. Second embodiment:
FIG. 7 is an explanatory diagram showing a part of the steps in the method of manufacturing the fuel cell according to the second embodiment. The second embodiment differs from the first embodiment only in the manufacturing process of the protective layer in the fuel cell manufacturing method. For this reason, in the fuel cell of the second embodiment, the same reference numerals are assigned to the portions common to the fuel cell of the first embodiment, and detailed description thereof is omitted.

  In the fuel cell manufacturing method of the second embodiment, unlike the first embodiment, the operation of applying the resin-containing liquid 52 in step S130 of FIG. 3 is performed twice. As described in the first embodiment, for example, when the resin-containing liquid layer 54 is formed using the resin-containing liquid 52 having a volume concentration of the polymer electrolyte of 50%, the solvent is volatilized from the resin-containing liquid layer 54. By doing so, the protective layer 32 having a thickness about half the thickness of the resin-containing liquid layer 54 is formed (see (A) and (B) of FIG. 4). Specifically, for example, the thickness of the gas diffusion layer 24 and the seal member 30 is 100 μm, and the resin-containing liquid layer having a thickness of 100 μm is applied by the first application using the resin-containing liquid 52 whose volume concentration of the electrolyte is 50%. When 54 is formed, the protective layer 32 having a thickness of 50 μm is formed. In the present embodiment, after the protective layer 32 is formed in this manner, the resin-containing liquid 52 is applied for the second time on the formed protective layer 32.

  In FIG. 7, the first application of the resin-containing liquid 52 is performed along the outer peripheral portion of the seal member 30, and the MEA 29 exposed by the gap 35 is exposed to the protective layer 32 formed by the first application. It represents a state in which the gas diffusion layer 24 is not completely covered and a part close to the outer periphery of the gas diffusion layer 24 is not covered. FIG. 7A shows a state where the resin-containing liquid 52 is applied for the second time along the outer periphery of the gas diffusion layer 24 on such a protective layer 32. In this way, when the resin-containing liquid 52 is applied so as to block the entire gap 35, and then the applied resin-containing liquid 52 is dried, the protective layer is half as thick as the layer of the resin-containing liquid 52 applied for the second time. 132 is formed. A state in which the protective layer 132 is formed is shown in FIG. In FIG. 7, since the second coating is performed along the outer periphery of the gas diffusion layer 24, the gap between the protective layer 32 and the outer periphery of the gas diffusion layer 24 is blocked by the second coating, and the second coating is performed. As a result of the coating, the thickness of the entire protective layer is increased. As described above, when the thickness of the gas diffusion layer 24 and the seal member 30 is 100 μm and the protective layer 32 of 50 μm is formed by the first application, the second application is performed to obtain 25 μm. The protective layer 132 is formed, and the total thickness of the protective layer is 75 μm. When the resin-containing liquid 52 is applied along the outer periphery of the seal member 30 or the gas diffusion layer 24, as described above, a position sensor is provided in the discharge device having the nozzle 50, and the seal member 30 or the gas diffusion layer is provided. What is necessary is just to detect the position of the outer periphery of the layer 24.

  According to the second embodiment configured as described above, the same effects as those of the first embodiment can be obtained. In particular, when the resin-containing liquid 52 is applied twice, the combined thickness of the protective layer and the electrolyte membrane 20 is increased, so that the effect of suppressing buckling of the electrolyte membrane in the gap 35 can be enhanced. Furthermore, since the area | region which is not covered with a protective layer in the clearance gap 35 can be reduced, the effect which suppresses the said buckling can be heightened more. In the second embodiment, the resin-containing liquid 52 is applied twice, but may be applied three or more times. Thereby, the thickness of the whole protective layer can be increased and the effect which suppresses the said buckling can further be heightened.

C. Variation:
Modification 1 (deformation related to the material of the protective layer):
In the first and second embodiments, the protective layer is formed using a resin-containing liquid 52 in which a polymer electrolyte similar to the electrolyte membrane 20 is dissolved or dispersed in a solvent such as water or alcohol. Also good. For example, the protective layer may be formed using a resin solution further including a resin material other than the polymer electrolyte. Alternatively, the protective layer may be composed of an electrolyte different from the polymer electrolyte that constitutes the electrolyte membrane 20. If the protective layer contains a polymer electrolyte, the protective layer swells and shrinks in the same manner as the electrolyte membrane 20, so that it is difficult for stress to occur at the interface between the protective layer and the MEA 29. However, if the protective layer is formed of the same kind of electrolyte as the electrolyte membrane 20 as in each embodiment, the rate of swelling and shrinkage between the protective layer and the electrolyte membrane 20 becomes closer, and the protective layer and the electrolyte membrane 20 It is more desirable because of increased affinity.

  The protective layer may be formed of a thermoplastic resin different from the polymer electrolyte, a thermosetting resin, or rubber. Examples of the thermoplastic resin for constituting the protective layer include polyethylene, polypropylene, or polyisobutylene (PIB). Moreover, as a thermosetting resin which comprises a protective layer, a phenol resin and an epoxy resin can be mentioned, for example. Examples of the rubber constituting the protective layer 32 include ethylene-propylene-diene rubber (EPDM), silicone rubber, fluorine rubber, butyl rubber, and natural rubber.

Modification 2 (deformation related to the protective layer forming process):
When forming the protective layer using the various materials described above, as the softened material for forming the protective layer, a material-containing liquid in which a material such as a resin is dissolved or dispersed in a solvent is used. A material obtained by heating and softening a resin or the like for forming the film can be used. Therefore, the material constituting the protective layer can be in a softened state as described above at the time of forming the protective layer, can be cured thereafter, and has a melting point higher than the operating temperature of the fuel cell, What is necessary is just to be stable in the internal environment of a battery. Even when a material obtained by heating a resin or the like for forming a protective layer to a molten state is used as the softened material, the viscosity of the softened material is sufficiently lowered by providing a heater in the nozzle 50. be able to.

  When the above-described thermoplastic resin is softened by heating to form a protective layer, for example, in step S140, the softened resin material is applied and then cooled, so that the applied resin layer is cured and the protective layer is formed. Can be formed. Further, in the case of forming the protective layer by softening the thermosetting resin described above, the applied resin layer is cured by heating after applying the softened resin material to form the protective layer. be able to. Alternatively, when a softened rubber material is used, the protective layer can be formed by performing a necessary treatment such as vulcanization after application of the softened rubber material. As described above, when the solvent is not vaporized during the formation of the protective layer, the thickness of the resin layer applied during the formation of the protective layer hardly changes. In addition, since it takes a relatively long time to cure the thermosetting resin by heating, from the viewpoint of shortening the production time, the protective layer is formed using a resin-containing liquid containing a solvent or a thermoplastic resin melted by heating. It is desirable to form.

Modification 3 (deformation related to the shape of the gas diffusion layer):
In the first and second embodiments, the cathode-side gas diffusion layer 24 is formed to be smaller than the anode-side gas diffusion layer 23, but the opposite configuration may be employed. The gas diffusion layer 23 may be formed smaller than the gas diffusion layer 24, and the outer periphery of the gas diffusion layer 23 may be disposed closer to the center than the outer periphery of the gas diffusion layer 24 and the electrolyte membrane 20. Also in this case, the same effect of suppressing buckling of the electrolyte membrane 20 can be obtained by applying the present invention. Moreover, the same effect is obtained that suppresses the cross leak between the oxidizing gas and the fuel gas and suppresses a short circuit between the gas diffusion layers with the electrolyte membrane 20 interposed therebetween.

  FIG. 8 is a plan view schematically showing the arrangement of the gas diffusion layers 223 and 224 in the fuel cell as a modification of the present invention. In the fuel cell according to the present invention, as in the first and second embodiments, the entire outer periphery of one gas diffusion layer need not be disposed closer to the center than the outer periphery of the other gas diffusion layer. In FIG. 8, as an example, among the two opposing sides of the rectangular gas diffusion layers 223 and 224, the gas diffusion layer 224 is arranged closer to the center of one set of sides, One set of sides represents a state in which the gas diffusion layer 224 is disposed at a position away from the center. At least a part of the outer periphery of one gas diffusion layer does not overlap with the other gas diffusion layer and the outer periphery of MEA 29 in the stacking direction of the gas diffusion layer, and a pair of outer periphery of the other gas diffusion layer and MEA 29 It suffices if it is arranged near the center of the gas diffusion layer. On the surface of the MEA 29 on which the one gas diffusion layer is provided, a seal member 30 is provided in the vicinity of the at least part of the outer periphery of the one gas diffusion layer, and the outer periphery of the one gas diffusion layer is The protective layer should just be provided so that at least one part of the clearance gap between at least one part and a sealing member may be block | closed. Thereby, the effect which suppresses the buckling of the electrolyte membrane (MEA29) in the said clearance gap can be acquired similarly to each embodiment.

Modification 4 (deformation related to the configuration of the gas flow path):
Although the embodiment has been described as a groove channel, it may have a different configuration. For example, by using a separator on a flat plate that does not have unevenness for forming the flow channel, a conductive porous member (for example, foam metal or extension metal) is disposed between the separator and the gas diffusion layer, and the above The in-cell gas flow path may be formed by pores in the porous member. Even in this case, a pair of gas diffusion layers whose outer periphery does not overlap in the stacking direction are used, and the outer periphery of one gas diffusion layer in which the outer periphery is disposed closer to the center of the gas diffusion layer than the other gas diffusion layer If the present invention is applied by providing a seal member in the vicinity and providing a protective layer in the gap between the outer periphery of the one gas diffusion layer and the seal member, the same effects as those of the embodiments can be obtained.

  The present invention is not limited to the above-described embodiments, examples, and modifications, and can be realized with various configurations without departing from the spirit thereof. For example, the technical features in the embodiments, examples, and modifications corresponding to the technical features in each embodiment described in the summary section of the invention are to solve some or all of the above-described problems, or In order to achieve part or all of the above effects, replacement or combination can be performed as appropriate. Further, if the technical feature is not described as essential in the present specification, it can be deleted as appropriate.

DESCRIPTION OF SYMBOLS 10 ... Single cell 20 ... Electrolyte membrane 21 ... Anode 22 ... Cathode 23, 24, 223, 224 ... Gas diffusion layer 25, 26 ... Gas separator 27, 28 ... Water-repellent layer 29 ... MEA
DESCRIPTION OF SYMBOLS 30 ... Seal member 32, 132 ... Protective layer 35 ... Gap 41, 42 ... Channel groove 50 ... Nozzle 52 ... Resin containing liquid 54 ... Resin containing liquid layer

Claims (3)

A membrane-electrode assembly in which electrodes are formed on both sides of an electrolyte membrane composed of a polymer electrolyte that swells by absorbing moisture and contracts by drying, and contacts each surface of the membrane-electrode assembly A first and a second gas diffusion layer disposed on the membrane-electrode assembly and configured by a conductive porous body,
At least a part of the outer periphery of the first gas diffusion layer and the outer periphery of the second gas diffusion layer and the membrane-electrode assembly overlap in the stacking direction of the first and second gas diffusion layers. The at least part of the outer periphery of the first gas diffusion layer is more central than the outer periphery of the second gas diffusion layer and the membrane-electrode assembly. It is located close to
In the fuel cell, on the surface of the membrane-electrode assembly on which the first gas diffusion layer is provided,
Oite in the vicinity of at least part of the outer periphery of the first gas diffusion layer, the membrane - in contact with the surface of the in the electrode assembly first gas diffusion layer is provided, of the first gas diffusion layer A seal member provided apart from the outer periphery ;
Moisture absorption is provided so as to close at least a part of a gap formed by a part of the wall surface by the at least part of the outer periphery of the first gas diffusion layer, the seal member, and the membrane-electrode assembly. A protective layer containing a polyelectrolyte that swells and shrinks when dried ,
A fuel cell comprising: A membrane-electrode assembly in which electrodes are formed on both sides of an electrolyte membrane composed of a polymer electrolyte that swells by absorbing moisture and contracts by drying, and contacts each surface of the membrane-electrode assembly A first and second gas diffusion layer disposed on the membrane-electrode assembly and configured by a conductive porous body,
A first step of preparing the membrane-electrode assembly;
If at least a part of the outer periphery of the first gas diffusion layer overlaps the outer periphery of the second gas diffusion layer and the membrane-electrode assembly in the stacking direction of the first and second gas diffusion layers. The at least part of the outer periphery of the first gas diffusion layer is more central than the outer periphery of the second gas diffusion layer and the membrane-electrode assembly than the central portion of the first and second gas diffusion layers. A second step of sandwiching the membrane-electrode assembly between the first and second gas diffusion layers so as to be disposed closer to each other;
The film - in contact with the surface of the in the electrode assembly first gas diffusion layer is provided, in the vicinity of at least part of the outer periphery of the first gas diffusion layer, from the outer periphery of the first gas diffusion layer A third step of disposing a separating seal member;
The film - on the plane of the in the electrode assembly first gas diffusion layer is provided, said first and said at least a portion of the outer periphery of the gas diffusion layer and the seal member and the film - by the electrode assembly wall of A fourth step of applying a softened material containing a polyelectrolyte to at least a part of a gap formed by a part;
A fifth step of curing the applied softened material to form a protective layer;
A method for manufacturing a fuel cell comprising: A method of manufacturing a fuel cell according to claim 2 ,
The fourth step is a step of applying a solution containing an electrolyte,
The fifth step is a method of manufacturing a fuel cell, wherein the protective layer containing the polymer electrolyte is formed by vaporizing a solvent in the solution.

Images