JP2015050134A - Membrane electrode assembly for fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a membrane electrode assembly for a fuel cell in which peeling of a diffusion layer and decrease in a power generation amount can be suppressed.SOLUTION: A membrane electrode assembly 11 for a fuel cell comprises: a polymer electrolyte membrane 111; an anode catalyst layer 112 and a cathode catalyst layer 113; an anode gas diffusion layer 114 of which an external marginal is matched with an external marginal of the anode catalyst layer; a cathode gas diffusion layer 115 of which an external marginal is matched with an external marginal of the cathode catalyst layer; and frame-like reinforcement layers 116, 117 which are arranged so that an internal marginal part of the reinforcement layer overlaps at least one of an external marginal part on the anode gas diffusion layer and an external marginal part on the cathode gas diffusion layer. An area Soverlapping between the internal marginal part of the reinforcement layer and the external marginal part of the anode gas diffusion layer or the cathode gas diffusion layer is 3%-12% of the power generation area S.

Description

  The present invention relates to a membrane electrode assembly for a fuel cell.

  In a fuel cell including an electrolyte membrane and a membrane electrode assembly including a catalyst layer formed on both sides of the electrolyte membrane, and a gas diffusion layer formed on both sides of the membrane electrode assembly, a peripheral portion of the membrane electrode assembly is provided. In order to reinforce the mechanical strength, a frame-shaped reinforcing film is sandwiched between the periphery of the membrane electrode assembly and the gas diffusion layer, and the catalyst layer and the reinforcing film are bonded with an adhesive polymer. (Patent Document 1).

JP 2010-80112 A

  However, when the frame-shaped reinforcing film is sandwiched between the peripheral edge portion of the membrane electrode assembly and the gas diffusion layer as in the above-described prior art, a step of the reinforcing film is generated at the outer peripheral end portion of the gas diffusion layer. There is a risk that the outer peripheral edge may peel off.

  The problem to be solved by the present invention is to provide a membrane electrode assembly for a fuel cell that can suppress peeling of the diffusion layer and a decrease in the amount of power generation.

  The present invention provides a polymer electrolyte membrane, an anode catalyst layer and a cathode catalyst layer provided on each of the first main surface and the second main surface of the polymer electrolyte membrane, and the same outer edge shape as the anode catalyst layer An anode gas diffusion layer provided on the anode catalyst layer so that the outer edge is aligned, and a cathode gas formed in the same outer edge shape as the cathode catalyst layer and provided so that the outer edge is aligned on the cathode catalyst layer A fuel cell comprising: a diffusion layer; and a frame-shaped reinforcing layer provided so that the inner edge overlaps at least one of the outer edge on the anode gas diffusion layer or the outer edge on the cathode gas diffusion layer In the membrane electrode assembly, the overlapping area of the inner edge of the reinforcing layer and the outer edge of the anode gas diffusion layer or the cathode gas diffusion layer is 3% to 12% with respect to the power generation area. To solve the above problems by a fuel cell membrane electrode assembly.

  In the above invention, the thickness of the reinforcing layer is preferably 12.5 μm to 125 μm. The reinforcing layer is preferably provided on both the outer edge portion on the anode gas diffusion layer and the outer edge portion on the cathode gas diffusion layer.

  According to the present invention, since the overlapping area between the inner edge of the reinforcing layer and the outer edge of the gas diffusion layer is 3% or more with respect to the power generation area, the outer edge of the gas diffusion layer is sufficiently suppressed by the inner edge of the reinforcing layer. Thus, peeling from the outer edge portion of the gas diffusion layer can be suppressed. On the other hand, since the area where the inner edge of the reinforcing layer overlaps with the outer edge of the gas diffusion layer is 12% or less of the power generation area, even if the outer edge of the gas diffusion layer is covered by the inner edge of the reinforcing layer, the gas The fuel supplied in the vicinity of the outer edge portion of the diffusion layer sufficiently circulates toward the outer edge, thereby suppressing a decrease in power generation amount.

1 is a partially exploded sectional view showing a fuel cell to which a membrane electrode assembly according to an embodiment of the present invention is applied. It is an expanded sectional view and a top view which show the membrane electrode assembly of FIG. It is sectional drawing which shows an example of the manufacturing method of the membrane electrode assembly of FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. A fuel cell 1 according to an embodiment of the present invention is a direct methanol fuel cell (DMFC) that generates electricity using methanol as a fuel, and includes a membrane-electrode assembly (MEA) 11 and The plate-like anode separator 14 and cathode separator 15 sandwiching the membrane electrode assembly 11, the anode current collector 12 provided on the outer surface of the anode separator 14, and the cathode current collector provided on the outer surface of the cathode separator 15 An electric body 13 and a gasket 18 provided inside the anode separator 14 and a gasket 19 provided inside the cathode separator 15 are provided. FIG. 1 shows the anode separator 14 and the cathode separator 15 in a state before being assembled with the membrane electrode assembly 11 interposed therebetween. From this state, the anode separator 14 and the cathode separator 15 sandwich the membrane electrode assembly 11. Assembled. 1 shows the configuration of the unit cell, a fuel cell in which a plurality of unit cells are stacked may be configured in accordance with the required electromotive force.

  The membrane electrode assembly 11 of this example includes a polymer electrolyte membrane 111 having hydrogen ion (cation) conductivity, an anode catalyst layer 112, a cathode catalyst layer 113, an anode gas diffusion layer 114, and a cathode gas diffusion layer. 115. The anode catalyst layer 112 and the anode gas diffusion layer 114 constitute an anode (fuel electrode), and the cathode catalyst layer 113 and the cathode gas diffusion layer 115 constitute a cathode (air electrode).

  The polymer electrolyte membrane 111 has an appropriate shape according to the outer shape of the fuel cell, such as a rectangle, a circle, an ellipse, or a polygon. The anode catalyst layer 112 and the cathode catalyst layer 113 are formed from the outer edge of the polymer electrolyte membrane 111. It has an appropriate shape such as a rectangle, a circle, an ellipse, or a polygon having a small outer edge. In addition, the anode gas diffusion layer 114 and the cathode gas diffusion layer 115 of this example have the same outer edge shape as the outer edge shapes of the anode catalyst layer 112 and the cathode catalyst layer 113, respectively, as shown in FIGS. 112 and the anode gas diffusion layer 114 are stacked so that their outer edges are aligned, and similarly, the cathode catalyst layer 113 and the cathode gas diffusion layer 115 are stacked so that their outer edges are aligned.

  The polymer electrolyte membrane 111 is not particularly limited, and a polymer electrolyte membrane mounted on a normal polymer electrolyte fuel cell can be used. For example, a polymer electrolyte membrane made of perfluorocarbon sulfonic acid, for example, Nafion (trade name, registered trademark) manufactured by DuPont, USA, Aciplex (trade name, registered trademark) manufactured by Asahi Kasei Corporation, manufactured by Asahi Glass Flemion (trade name, registered trademark) or the like can be used. The thickness of the polymer electrolyte membrane 111 is not particularly limited, but is usually 25 to 250 μm.

  The anode catalyst layer 112 and the cathode catalyst layer 113 are made of, for example, an electrode catalyst such as a platinum-based metal catalyst, conductive carbon particles (carbon powder) carrying the electrode catalyst, and a polymer electrolyte having hydrogen ion conductivity. It is configured. The thicknesses of the anode catalyst layer 112 and the cathode catalyst layer 113 are not particularly limited, but are usually 5 to 50 μm.

  As the conductive carbon particles which are carriers in the anode catalyst layer 112 and the cathode catalyst layer 113, it is preferable to use a carbon material having conductive pores, such as carbon black, activated carbon, carbon fiber and carbon tube. Can be used. Examples of carbon black include channel black, furnace black, thermal black, and acetylene black. Activated carbon can be obtained by carbonizing and activating materials containing various carbon atoms.

  As an electrode catalyst in the anode catalyst layer 112 and the cathode catalyst layer 113, it is preferable to use platinum or a platinum alloy. Platinum alloys include platinum group metals other than platinum (ruthenium, rhodium, palladium, osmium, iridium), iron, titanium, gold, silver, chromium, manganese, molybdenum, tungsten, aluminum, silicon, rhenium, zinc, and tin. An alloy of platinum and one or more metals selected from the group is preferably used. In particular, in the anode catalyst layer 112, there is a problem that carbon monoxide as an intermediate product poisons the platinum catalyst. Therefore, it is preferable that the anode catalyst layer 112 contains ruthenium or the like having carbon monoxide resistance. The platinum alloy may contain an intermetallic compound of platinum and the metal. Furthermore, an electrode catalyst mixture obtained by mixing an electrode catalyst made of platinum and an electrode catalyst made of a platinum alloy may be used, or the same electrode catalyst may be used on the anode side and the cathode side, or different electrode catalysts may be used. .

  As the polymer electrolyte contained in the anode catalyst layer 112 and the cathode catalyst layer 113 and attached to the catalyst-supporting particles, a polymer electrolyte constituting the polymer electrolyte membrane 111 can be used. The polymer electrolyte constituting the anode catalyst layer 112, the cathode catalyst layer 113, and the polymer electrolyte membrane 111 may be of the same type or different types. For example, Nafion (trade name, registered trademark) manufactured by DuPont, Inc., Aciplex (trade name, registered trademark) manufactured by Asahi Kasei Co., Ltd., Flemion (trade name, registered trademark) manufactured by Asahi Glass Co., Ltd., etc. Can be used.

  The polymer electrolyte in the anode catalyst layer 112 and the cathode catalyst layer 113 covers the catalyst-supported particles, and the catalyst-supported particles constituting the anode catalyst layer 112 and the cathode catalyst layer 113 in order to secure a three-dimensional hydrogen ion conduction path. The anode catalyst layer 112 and the cathode catalyst layer 113 are preferably contained in an amount proportional to the mass of the catalyst. Specifically, the mass of the polymer electrolyte contained in the anode catalyst layer 112 and the cathode catalyst layer 113 is desirably 0.2 times or more and 2.0 times or less with respect to the mass of the catalyst-carrying particles. Within this range, high battery output can be obtained. As described above, if the mass of the polymer electrolyte is 0.2 times or more, sufficient hydrogen ion conductivity can be ensured, and if it is 2.0 times or less, flooding can be avoided, resulting in higher battery output. Can be realized.

  The anode gas diffusion layer 114 and the cathode gas diffusion layer 115 are disposed above the anode catalyst layer 112 and the cathode catalyst layer 113, respectively, and methanol flowing in from the anode channel 16 and the cathode channel 17 of the anode separator 14 and the cathode separator 15 The anode catalyst layer 112 and the cathode catalyst layer 113 and the cathode catalyst layer 113 are not particularly limited as long as they have a function and conductivity that efficiently guide them, and various gas diffusion layers known in the art can be used. As the base material constituting these gas diffusion layers 114 and 115, in order to provide gas permeability, carbon fine powder having a developed structure structure, pore former, carbon paper, carbon cloth, or the like is used. In addition, a conductive porous substrate can be used. In order to improve drainage, for example, polytetrafluoroethylene (PTFE), tetrafluoroethylene / hexafluoropropylene copolymer (FEP), tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer (PFA), tetra A water repellent material (polymer) typified by a fluororesin such as fluoroethylene / ethylene copolymer (ETFE) may be dispersed inside the base material, and the base material may be subjected to a water repellent treatment. Furthermore, in order to give electronic conductivity, you may comprise the said base material with electronic conductive materials, such as a carbon fiber, a metal fiber, or a carbon fine powder. The same gas diffusion layer or different gas diffusion layers may be used on the cathode side and the anode side. The thickness of the anode gas diffusion layer 114 and the cathode gas diffusion layer 115 is not particularly limited, but is usually 100 to 500 μm.

  The pair of anode separator 14 and cathode separator 15 has an appropriate outer shape corresponding to the outer shape of the membrane electrode assembly 11, and is disposed outside the membrane electrode assembly 11 to mechanically connect the membrane electrode assembly 11. It is a member having conductivity for fixing. The surface of the anode separator 14 that is in contact with the membrane electrode assembly 11 is supplied with methanol as a fuel to the anode to carry away the electrode reaction product and the substance containing unreacted methanol from the reaction field to the outside. Similarly, the anode channel 16 is formed, and the surface of the cathode separator 15 in contact with the membrane electrode assembly 11 is supplied with oxygen (air) to the cathode, and contains an electrode reaction product and unreacted methanol. A cathode channel 17 is formed to carry the substance from the reaction field to the outside.

  Although not shown, the anode channel 16 and the cathode channel 17 are formed by providing grooves on the surfaces of the anode separator 14 and the cathode separator 15, respectively, by a conventional method. Although not particularly limited, the anode flow channel 16 and the cathode flow channel 17 are constituted by, for example, a plurality of linear groove portions and a plurality of turn-shaped groove portions that connect adjacent linear groove portions from upstream to downstream. It has a serpentine shape.

  The gaskets 18 and 19 have a shape corresponding to the outer shape of the anode separator 14 and the cathode separator 15 and have a frame shape (frame shape) or an annular shape. The fuel gas and the oxidant gas supplied to the unit cell are connected to the outside. In order to prevent leakage and mixing, they are arranged around the anode and the cathode (in particular, the anode gas diffusion layer 114 and the cathode gas diffusion layer 115), respectively. As shown in FIG. 1, the inner edge of the gasket 18 is sized outside the outer edge of the anode catalyst layer 112 and the outer edge of the anode gas diffusion layer 114 and inside the outer edge of the polymer electrolyte membrane 111. . Similarly, the inner edge of the gasket 19 is sized outside the outer edge of the cathode catalyst layer 113 and the outer edge of the cathode gas diffusion layer 115 and inside the outer edge of the polymer electrolyte membrane 111. This is because if the inner edge portions of the gaskets 18 and 19 overlap with the gas diffusion layers 114 and 115, only those portions become excessively thick and cause fuel leakage. Further, if the inner edges of the gaskets 18 and 19 are outside the polymer electrolyte membrane 111, the thickness is insufficient and fuel leakage occurs. As such gaskets 18 and 19, those known in the art such as rubber can be used.

  As the anode current collector 12 and the cathode current collector 13, a conductive metal plate having a thickness of 1 to 3 mm, for example, a metal plate (such as a copper plate) coated with 3 to 4 μm of gold can be used. The anode current collector 12 is provided on the outer surface of the conductive anode separator 14, and the cathode current collector 13 is provided on the outer surface of the conductive cathode separator 15. In the assembled state of the fuel cell 1, the anode current collector 12 is connected to the cathode (minus) of the power load, and the cathode current collector 13 is connected to the anode (plus) of the power load. Power is supplied to the power load.

In the fuel cell 1 configured as described above, when methanol is supplied to the inlet of the anode channel 16 of the anode separator 14 and air is supplied to the inlet of the cathode channel 17 of the cathode separator 15,
[Equation 1]
CH ₃ OH + H ₂ O → CO ₂ + 6H ⁺ + 6e ⁻
Oxidation reaction occurs, and at the cathode,
[Equation 2]
1 / 2O ₂ + 6H ⁺ + 6e ⁻ → 3H ₂ O
The reduction reaction occurs. As a result, a current flows between the anode and the cathode.

  Now, in order to increase the mechanical strength of the membrane electrode assembly 11, the membrane electrode assembly 11 of this example has a frame shape provided so that the inner edge portion overlaps the outer edge portion of the upper surface of the anode gas diffusion layer 114. The frame-shaped second reinforcing layer 117 is provided on the outer edge portion of the upper surface of the cathode gas diffusion layer 115 so as to overlap the inner edge portion. In order to increase the mechanical strength of the membrane electrode assembly 11, it is preferable to provide both the first reinforcing layer 116 and the second reinforcing layer 117, but at least one of the membrane electrode assemblies of the present invention is provided. You should prepare.

  The first reinforcing layer 116 and the second reinforcing layer 117 in this example are not particularly limited as long as they have a desired rigidity. For example, a film made of polyethylene terephthalate PET, polyethylene naphthalate PEN, polytetrafluoroethylene PTFE, etc. can be used. More preferably, it is used.

  An adhesive is applied to one main surface (the main surfaces opposite to each other in FIGS. 1 and 2) of the first reinforcing layer 116 and the second reinforcing layer 117 of this example. As this adhesive, it is possible to bond between the polymer electrolyte membrane 111 and the gas diffusion layers 114 and 115 by heating and pressing using a hot press machine or the like, and in the operating temperature range of the fuel cell 1. There is no particular limitation as long as the property can be secured. For example, an adhesive mainly composed of an acrylic resin or a urethane resin can be used. As will be described later, since the first reinforcing layer 116 and the second reinforcing layer 117 are bonded by hot pressing at the reaction temperature of the adhesive, it is necessary to be a material having a melting point higher than the reaction temperature of the adhesive. It is said.

In particular the frame-shaped first reinforcing layer 116 of the present embodiment, the inner edge 116A are stacked so as to overlap the outer edge portion 114A of the anode gas diffusion layer 114, these overlapped area _{S 1} is, 3 to the generator area _{S 0} % To 12% (= S ₁ / S ₀ ). Similarly, a frame shape second reinforcing layer 117 has its inner edge 117A are stacked so as to overlap the outer edge portion 115A of the cathode gas diffusion layer 115, these overlapped area _{S 1} is 3% with respect to the power generation area _{S 0} It is provided to be ˜12% (= S ₁ / S ₀ ). Since the overlapping condition between the first reinforcing layer 116 and the anode gas diffusion layer 114 and the overlapping condition between the second reinforcing layer 117 and the cathode gas diffusion layer 115 are the same, the first reinforcing layer 116 and the anode gas diffusion layer 114 The relationship will be described with reference to FIG.

The power generation area referred to in this example is an area where the oxidation reaction at the anode and the reduction reaction at the cathode described above can occur effectively, and are the areas of the anode catalyst layer 112 and the cathode catalyst layer 113, respectively. In contrast, the area _{S 1} of the outer edge portion 114A are overlapped inner edge 116A and the anode gas diffusion layer 114 of the first reinforcing layer 116, as shown in the lower part of FIG. 2 (plan view), an anode gas diffusion This is an area (S ₁ = S ₂ −S ₃ ) obtained by subtracting the area S ₃ of the rectangular opening formed by the inner edge of the first reinforcing layer 116 from the area S _{2 of the} layer 114.

As in the membrane electrode assembly 11 of this example, when the first reinforcing layer 116 is overlaid on the upper surface of the anode gas diffusion layer 114, peeling from the outer edge of the anode gas diffusion layer 114 is suppressed, while the anode gas diffusion layer 114. upper surface of the outer edge portion 114A is that the power generation area S ₀ of the apparent order to be covered with the first reinforcing layer 116 is reduced in. However, since the methanol and oxygen introduced into the outer edge portion 114A of the anode gas diffusion layer 114 reach and reach the outer edge of the anode catalyst layer 112 by the diffusion action of the anode gas diffusion layer 114, the present inventors have made this overlap. It has been found that by setting the area to an appropriate value, it is possible to achieve both prevention of peeling of the anode gas diffusion layer 114 and prevention of reduction in power generation amount.

That is, if the area S ₁ where the inner edge portion 116A of the first reinforcing layer 116 and the outer edge portion 114A of the anode gas diffusion layer 114 overlap is set to 3% or more of the power generation area S ₀ , the anode gas diffusion layer 114 will not peel off. While it can be effectively prevented, if the area S ₁ where the inner edge portion 116A of the first reinforcing layer 116 and the outer edge portion 114A of the anode gas diffusion layer 114 overlap is set to 12% or less of the power generation area S ₀ , the first reinforcing layer A power generation amount equivalent to that without 116 is obtained, and a decrease in the power generation amount due to the provision of the first reinforcing layer 116 can be prevented. The same applies to the overlapping condition between the second reinforcing layer 117 and the cathode gas diffusion layer 115.

  It is preferable that the thickness of the 1st reinforcement layer 116 and the 2nd reinforcement layer 117 is 12.5-125 micrometers including an adhesive agent. Even if the thickness of the first reinforcing layer 116 and the second reinforcing layer 117 is less than 12.5 μm, the purpose of improving the mechanical strength of the membrane electrode assembly 11 can be achieved. Is damaged. If the thickness exceeds 125 μm, the steps generated at the inner edges of the first reinforcing layer 116 and the second reinforcing layer 117 become large, so that the end portions of the anode catalyst layer 112 and the anode gas diffusion layer 114 are present in the first reinforcing layer 116. In the second reinforcing layer 117, cavities are generated at the ends of the cathode catalyst layer 113 and the cathode gas diffusion layer 115, and the electromotive force may be reduced.

  The outer edge portions of the first reinforcing layer 116 and the second reinforcing layer 117 in this example extend so as to cover the end portion of the polymer electrolyte membrane 111, and both the reinforcing layers 116 and 117 are bonded together. Thereby, the mechanical strength of the membrane electrode assembly 11 including the polymer electrolyte membrane 111, the catalyst layers 113 and 114, and the gas diffusion layers 115 and 116 is improved. In the membrane electrode assembly of the present invention, if at least one of the first reinforcing layer 116 and the second reinforcing layer 117 is provided, the purpose of improving the mechanical strength can be achieved, but the reinforcing layers 116, 117 and the gas Since the bonding between the diffusion layers 115 and 116 and the polymer electrolyte membrane 111 is basically a bonding of different materials, there is a possibility of warping depending on the operating temperature. Therefore, as in this example Most preferably, both the first reinforcing layer 116 and the second reinforcing layer 117 are provided.

  Next, the manufacturing method of the membrane electrode assembly 11 of this example is demonstrated. FIG. 3 is a cross-sectional view for explaining a process of manufacturing the membrane electrode assembly 11 of this example using a hot press machine. The hot press machine 5 includes a first hot platen 51 whose position is fixed, and a second hot platen 52 that moves up and down by a pressure cylinder 55 with respect to the first hot platen 51, The second heating plates 52 are each connected to a heat source and configured to be heated to a desired temperature.

  After the membrane electrode assembly 11 of this example is set on the jig 53, the jig 53 is set on the hot press machine 5. The jig 53 is provided with positioning and fixing pins 54 at the four corners. On the other hand, positions corresponding to the positioning and fixing pins 54 at the four corners of the polymer electrolyte membrane 111, the first reinforcing layer 116 and the second reinforcing layer 117. The positioning and fixing holes 111h, 116h, and 117h are formed.

  When manufacturing the membrane electrode assembly 11 of this example, the anode catalyst layer 112 and the cathode catalyst layer 113 are formed in advance at predetermined positions on both main surfaces of the polymer electrolyte membrane 111. This can be performed by spray-coating the material constituting the anode catalyst layer 112 and the cathode catalyst layer 113 on both main surfaces of the polymer electrolyte membrane 111 and drying. Alternatively, the anode catalyst layer 112 and the cathode catalyst layer 113 may be thermally transferred to both main surfaces of the polymer electrolyte membrane 111.

  The jig 53 of the hot press machine 5 is set in the stacking order of the layers constituting the membrane electrode assembly 11. That is, the four positioning fixing holes 117h of the second reinforcing layer 117 are placed on the jig 53 while being inserted into the four positioning fixing pins 54 of the jig 53, and then the opening of the inner edge of the second reinforcing layer 117 The cathode gas diffusion layer 115 is placed on the second reinforcing layer 117 with reference to the positioning reference.

  The same applies to the following, but cathode gas diffusion is not performed using the positioning fixing pins 54 and the positioning fixing holes 111h, 116h, and 117h, and the opening at the inner edge of the second reinforcing layer 117 is used as a positioning reference. In order to place the layer 115 on the second reinforcing layer 117, the second reinforcing layer 117 placed on the jig 53 and the cathode gas diffusion layer 115 to be set next are photographed by a fixed camera, The robot is controlled while analyzing the image position of the cathode gas diffusion layer 115 based on the image position of the opening of the second reinforcement layer 117, and the cathode gas diffusion layer 115 is placed in the second reinforcement layer 117 so as to be at a predetermined position. Just place it on top.

  Next, the jig is inserted into the four positioning fixing pins 54 of the jig 53 while the four positioning fixing holes 111h of the polymer electrolyte membrane 111 provided with the anode catalyst layer 112 and the cathode catalyst layer 113 on both main surfaces are inserted. 53. Next, the anode gas diffusion layer 114 is placed on the anode catalyst layer 112 using the anode catalyst layer 112 as a positioning reference. This set can be performed by image analysis using a fixed camera. Next, the four positioning fixing holes 116 of the first reinforcing layer 116 are placed on the jig 53 while being inserted into the four positioning fixing pins 54 of the jig 53.

  Note that the anode current collector 12 and the cathode current collector 13 may be integrally formed as necessary. In this case, the cathode current collector 13 is set between the second reinforcing layer 117 and the cathode gas diffusion layer 115 described above, and the anode current collector 12 is interposed between the anode gas diffusion layer 114 and the first reinforcement layer 116. Should be set.

  After each layer constituting the membrane electrode assembly 11 is set in the jig 53 as described above, this is set in the hot press machine 5 and the first hot platen 51 and the second hot platen 52 are heated to a predetermined temperature. The pressure cylinder 55 is driven to lower the second hot platen 52, and a predetermined pressure is applied for a predetermined time. Thereby, the adhesive agent formed in the 1st reinforcement layer 116 and the 2nd reinforcement layer 117 reacts, and both reinforcement layers 116 and 117 adhere | attach firmly. As a result, the polymer electrolyte membrane 111 provided with the anode catalyst layer 112 and the cathode catalyst layer 113 on both main surfaces and the gas diffusion layers 114 and 115 are also firmly bonded.

  Hereinafter, the present invention will be described with reference to examples that further embody the present invention and comparative examples for the examples. However, various conditions such as numerical values and materials in the following examples are merely examples of the present invention and do not limit the present invention.

Example 1
As the polymer electrolyte membrane 111, a polymer electrolyte membrane made of perfluorocarbon sulfonic acid having a length of 200 mm, a width of 200 mm, and a thickness of 125 μm (Nafion (trade name, registered trademark) manufactured by DuPont, USA) is used.
As the anode catalyst layer 112, a platinum / ruthenium catalyst having a length of 146 mm, a width of 128 mm, and a thickness of 40 μm (TEC66E50 manufactured by Tanaka Kikinzoku Co., Ltd., platinum / ruthenium loading amount of 50% by weight) was used.
As the cathode catalyst 113, a platinum catalyst having a length of 146 mm, a width of 128 mm, and a thickness of 20 μm (TEC10E70TPM manufactured by Tanaka Kikinzoku Co., Ltd., platinum loading 70 wt%) was used.
As the anode gas diffusion layer 114 and the cathode gas diffusion layer 115, a graphite fiber nonwoven fabric (carbon fiber paper SIGRACET GDL25BC manufactured by MFC Technology) having a length of 146 mm, a width of 128 mm, and a thickness of 235 μm is used.
As the first reinforcing layer 116 and the second reinforcing layer 117, a polyethylene naphthalate film (Teonex manufactured by Teijin DuPont Films) having an outer edge length of 210 mm, an outer edge width of 210 mm, an inner edge length of 140 mm, an inner edge width of 123 mm, and a thickness of 25 μm is used. Using. The power generation area in this example is 146 mm long × 128 mm wide = 18688 mm ² , the inner edge portion of the first reinforcing layer 116 (or the second reinforcing layer 117) and the outer edge portion of the anode gas diffusion layer 114 (or the cathode gas diffusion layer 115). The overlapping area was 1468 mm ² , and the area ratio was 8%.

  First, the anode catalyst layer 112 and the cathode catalyst layer 113 were spray-coated on both main surfaces of the polymer electrolyte membrane 111 and dried. As shown in FIG. 3, the polymer electrolyte membrane 111, the anode gas diffusion layer 114, and the first reinforcement layer 116 on which the second reinforcing layer 117, the cathode gas diffusion layer 115, the anode catalyst layer 112, and the cathode catalyst layer 113 are formed. Then, using the hot press machine 5, a heat and pressure treatment was performed at a temperature of 130 ° C. and a pressure of 3 MPa for 5 minutes.

  The membrane / electrode assembly 11 thus obtained was visually observed to confirm whether the gas diffusion layers 114 and 115 were peeled off. Moreover, the fuel cell 1 was assembled using the obtained membrane electrode assembly 11, and it was confirmed whether or not the membrane electrode assembly 11 would break when grasped as workability at that time. Further, methanol and air were supplied to the assembled fuel cell to perform an operation test, and the electromotive force of the unit cell was measured. The results are shown in Table 1.

<< Examples 2 to 5 >>
By changing the vertical and horizontal dimensions of the inner edges of the first reinforcing layer 116 and the second reinforcing layer 117 in the first embodiment, the inner edges of the first reinforcing layer 116 and the second reinforcing layer 117, the anode gas diffusion layer 114, and A membrane / electrode assembly 11 was produced under the same conditions as in Example 1 except that the area ratio of the overlapping area with the outer edge of the cathode gas diffusion layer 115 was 3%, 5%, 10%, and 12%. The same evaluation was performed. These results are shown in Table 1.

<< Comparative Example 1 >>
As a comparative example of Examples 1 to 5, a membrane electrode assembly 11 was produced under the same conditions as in Example 1 except that the first reinforcing layer 116 and the second reinforcing layer 117 of Example 1 were omitted, and the same evaluation was performed. went. The results are shown in Table 1.

<< Comparative Examples 2-4 >>
As a comparative example of Examples 1 to 5, the first reinforcing layer 116 and the second reinforcing layer 117 are changed by changing the vertical dimension and the horizontal dimension of the inner edges of the first reinforcing layer 116 and the second reinforcing layer 117 in Example 1. A membrane electrode under the same conditions as in Example 1 except that the area ratio of the overlapping area of the inner edge portion of the anode and the outer edge portion of the anode gas diffusion layer 114 and the cathode gas diffusion layer 115 was 1%, 2%, and 15%. A joined body 11 was prepared and subjected to the same evaluation. These results are shown in Table 1.

<Discussion 1>
From the results of Examples 1 to 5 and Comparative Examples 1 to 4, in Comparative Example 1 in which the reinforcing layers 116 and 117 are omitted, the gas diffusion layers 114 and 115 are peeled almost over the entire circumference, and the reinforcing layers 116 and 117 are removed. Also in Comparative Examples 2 and 3 in which the area ratio where the gas diffusion layers 114 and 115 overlap was 2% or less, the gas diffusion layers 114 and 115 were partly peeled off. Further, in Comparative Example 4 in which the area ratio was 15% or more, no peeling failure occurred, but the electromotive force of the single cell was reduced to 88% compared to that of Comparative Example 1 without the reinforcing layers 116 and 117. .

  On the other hand, in the membrane electrode assembly 11 of Examples 1 to 5 in which the area ratio of the reinforcing layers 116 and 117 and the gas diffusion layers 114 and 115 is 3% to 12%, the gas diffusion layer 114 is used. 115 was not observed at all. The electromotive force also decreased to 96% even in the minimum Example 5 as compared with Comparative Example 1 without the reinforcing layers 116 and 117.

<< Examples 6 to 10 >>
The membrane electrode assembly 11 under the same conditions as in Example 1 except that the thickness dimensions of the first reinforcing layer 116 and the second reinforcing layer 117 in Example 1 were changed to 12.5 μm, 50 μm, 75 μm, 100 μm, and 125 μm, respectively. The same evaluation was performed. These results are shown in Table 2 together with Example 1.

<< Comparative Examples 5-7 >>
As a comparative example of Examples 1 and 6 to 10, the same conditions as in Example 1 except that the thickness dimensions of the first reinforcing layer 116 and the second reinforcing layer 117 in Example 1 were changed to 10 μm, 188 μm, and 250, respectively. Membrane / electrode assembly 11 was prepared and subjected to the same evaluation. These results are shown in Table 2 together with Example 1.

<Discussion 2>
From the results of Examples 1, 6 to 10 and Comparative Examples 5 to 7, in Comparative Example 5 where the thickness of the reinforcing layers 116 and 117 is as thin as 10 μm, when the membrane electrode assembly 11 is gripped, it is bent and the shape is stabilized. The subsequent assembly workability was remarkably bad. When the thickness of the reinforcing layers 116 and 117 is 188 μm or more, the workability of the membrane electrode assembly 11 is good, but the electromotive force of the unit cell is higher than that of the comparative example 1 without the reinforcing layers 116 and 117. In Comparative Example 6, it decreased to 90% and in Comparative Example 7 to 76%.

  On the other hand, in the membrane electrode assemblies 11 of Examples 1 and 6 to 10 in which the thickness dimensions of the reinforcing layers 116 and 117 are 12.5 μm to 125 μm, the workability of the membrane electrode assembly 11 is good. Moreover, the electromotive force of the single cell was reduced to 99% even in the minimum Example 10 as compared with Comparative Example 1 without the reinforcing layers 116 and 117.

DESCRIPTION OF SYMBOLS 1 ... Fuel cell 11 ... Membrane electrode assembly 111 ... Polymer electrolyte membrane 112 ... Anode catalyst layer (fuel electrode)
113 ... Cathode catalyst layer (air electrode)
DESCRIPTION OF SYMBOLS 114 ... Anode gas diffusion layer 115 ... Cathode gas diffusion layer 116 ... 1st reinforcement layer 117 ... 2nd reinforcement layer 12 ... Anode collector 13 ... Cathode collector 14 ... Anode separator 15 ... Cathode separator 16 ... Anode flow path 17 ... Cathode channel 18, 19 ... Gasket 5 ... Hot press machine 51 ... First hot plate 52 ... Second hot plate 53 ... Jig 54 ... Pin for positioning and fixing 55 ... Pressure cylinder

Claims (2)

A polymer electrolyte membrane;
An anode catalyst layer and a cathode catalyst layer provided on each of the first main surface and the second main surface of the polymer electrolyte membrane;
An anode gas diffusion layer formed in the same outer edge shape as the anode catalyst layer and provided so that the outer edge is aligned on the anode catalyst layer;
A cathode gas diffusion layer formed in the same outer edge shape as the cathode catalyst layer and provided so that the outer edge is aligned on the cathode catalyst layer;
A fuel cell membrane electrode assembly comprising: a frame-shaped reinforcing layer provided on at least one of an outer edge portion on the anode gas diffusion layer and an outer edge portion on the cathode gas diffusion layer so that the inner edge portion overlaps the outer edge portion. In
A membrane electrode assembly for a fuel cell, wherein an overlapping area between an inner edge portion of the reinforcing layer and an outer edge portion on the anode gas diffusion layer or the cathode gas diffusion layer is 3% to 12% with respect to a power generation area.   The membrane electrode assembly for a fuel cell according to claim 1, wherein the reinforcing layer has a thickness of 12.5 μm to 125 μm.

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