JP6131669B2 - Membrane electrode assembly and manufacturing method thereof - Google Patents

Description

  The present invention relates to a membrane electrode assembly in a polymer electrolyte fuel cell and a method for producing the same.

In the movement toward building a decarbonized society, hydrogen is attracting attention as an intermediate energy carrier. Development of a fuel cell is underway as one form of utilization of hydrogen energy.
In particular, among various fuel cells, polymer electrolyte fuel cells are expected to be put to practical use as power sources for automobiles or households because of their high power density, low temperature operation, and compact battery body. Yes.

A fuel cell is a power generation system that extracts electric power by electrochemically reacting a fuel gas such as hydrogen and an oxidizing gas such as air. The membrane electrode assembly in the polymer electrolyte fuel cell is composed of, for example, an electrolyte membrane, a catalyst layer, a gas diffusion layer, and a gasket layer. The gasket layer constituting a part of the membrane electrode assembly is required to support the electrolyte and contribute to the suppression of oxygen and hydrogen leakage and the maintenance of the humidity of the electrolyte membrane.
From the viewpoint of manufacturing, a membrane electrode assembly structure with a small number of parts and easy assembly is desirable, and a membrane electrode assembly structure capable of a lamination process can be expected to shorten manufacturing time. In particular, those including a lamination process by printing are desirable in terms of mass production and continuous production.

Patent Document 1 proposes a method of sealing resin on the gasket end face with an injection mold. In this method, a large amount of material resin is required, and productivity is poor from the viewpoint of processing speed, resulting in high cost.
Further, in Patent Document 2, a lamination process is possible, and as a method capable of mass production, a gasket is used as a sheet composed of two layers of a barrier layer and a welding layer, and end faces are welded and sealed.

Registration No. 4742043 JP 2009-81115 A

However, polyolefin usually used as a gasket weld layer has an adhesion temperature of 130 ° C., which is close to the power generation temperature, and may be softened. In addition, there is a concern about the influence on the electrolyte membrane due to bleeding out of additives such as lubricants, antistatic agents, plasticizers and antioxidants used for improving processability.
In view of the above-described problems in the background art, an object of the present invention is to provide a membrane electrode assembly in a polymer electrolyte fuel cell having high sealing performance at a reduced cost.

  In order to solve the above problems, a membrane electrode assembly according to the first aspect of the present invention includes an electrolyte membrane, a cathode catalyst layer disposed on one surface side of the electrolyte membrane, and the other of the electrolyte membranes. And an anode catalyst layer disposed on the surface side of the catalyst electrode, and each of the gasket layers disposed on the electrolyte membrane at an outer periphery of the catalyst layer, and each gasket layer is on the electrolyte membrane side. And a second gasket laminated on the first gasket, and the second gasket on the cathode catalyst layer side and the second gasket on the anode catalyst layer side are made continuous. .

As a 2nd aspect, the thickness of each gasket layer which consists of the 1st gasket and the 2nd gasket arrange | positioned on the outer periphery of each catalyst layer with respect to a 1st aspect is each catalyst on the side each arrange | positioned It is characterized by being equal to the thickness of the layer.
As a third aspect, in contrast to the first or second aspect, the first gasket is made of a single layer thermoplastic resin film.

As a fourth aspect, in contrast to the first to third aspects, the second gasket is made of a thermoplastic resin film having an adhesive layer.
As a fifth aspect, in contrast to the first to fourth aspects, both the first and second gaskets are polyester resins.
As a sixth aspect, in contrast to the first to fifth aspects, both the first and second gaskets are biaxially stretched polyethylene naphthalate.

As a seventh aspect, the second gasket is characterized in that a base film is coated with a resin that melts at 100 ° C. or higher, or a heat-resistant adhesive layer.
The eighth aspect includes an electrolyte membrane, a cathode catalyst layer disposed on one surface side of the electrolyte membrane, an anode catalyst layer disposed on the other surface side of the electrolyte membrane, and an outer periphery of each catalyst layer. Each gasket layer disposed on the electrolyte membrane, and each gasket layer has a first gasket on the electrolyte membrane side and a second gasket laminated on the first gasket layer. The gasket is wider than the first gasket, and the end face of the first gasket and the end face of the electrolyte membrane are covered with the end of the second gasket.

  The method for producing a membrane electrode assembly according to the ninth aspect includes an electrolyte membrane, a cathode catalyst layer disposed on one surface side of the electrolyte membrane, and an anode catalyst disposed on the other surface side of the electrolyte membrane. Each gasket layer disposed on the electrolyte membrane at the outer periphery of each catalyst layer, and each gasket layer includes a first gasket on the electrolyte membrane side and a second layer laminated thereon. A second gasket is set wider than the first gasket, and an end face of the first gasmet and an end face of the electrolyte membrane are covered with an end portion of the second gasket. To do.

  According to one embodiment of the present invention, it is possible to cover the end face of the electrolyte membrane only by continuing the second gasket on the cathode catalyst layer side and the second gasket on the anode catalyst layer side, and has high sealing performance. A membrane electrode assembly in a polymer electrolyte fuel cell can be provided. That is, by covering the end surface with the second gasket, it is possible to ensure gas barrier properties, and since there are few contact surfaces to the electrolyte membrane, it is possible to suppress the influence of the adhesive layer such as bleed out.

Here, by constituting the gasket from a thermoplastic resin film, it is possible to prevent the permeation of the fuel gas and the oxidizing gas, and to give the gasket a function capable of withstanding heat generation during power generation.
Further, by using a biaxially stretched polyester naphthalate single layer, which is a heat resistant film, as the first gasket, the heat resistance during power generation is improved, and the possibility of bleeding out of the additive in the weld layer is eliminated.

It is a schematic sectional drawing of the membrane electrode assembly in the polymer electrolyte fuel cell concerning embodiment of this invention. It is a figure of each lamination | stacking part of the membrane electrode assembly in the polymer electrolyte fuel cell concerning embodiment of this invention. It is a manufacturing process of the membrane electrode assembly in the polymer electrolyte fuel cell concerning embodiment of this invention.

Hereinafter, the membrane electrode assembly in the polymer electrolyte fuel cell according to the embodiment of the present invention will be described.
FIG. 1 is a cross-sectional view of a membrane electrode assembly 10 in a polymer electrolyte fuel cell according to an embodiment of the present invention.
As shown in FIGS. 1 and 2, a membrane electrode assembly 10 according to an embodiment of the present invention includes an electrolyte membrane 1, a cathode catalyst layer 2 disposed on one surface side of the electrolyte membrane 1, and the electrolyte. An anode catalyst layer 3 disposed on the other surface side of the membrane 1. The area of the electrolyte membrane 1 is slightly larger than the interview of the catalyst layers 2 and 3, and gasket layers are disposed around the catalyst layers 2 and 3, respectively. Each gasket layer includes first gaskets 4 and 5 and a second gasket 6 which are laminated. The outer circumference of the second gasket 6 is larger than the first gaskets 4 and 5.

And in FIG. 1, the edge parts of the 2nd gasket 6 which makes a pair up and down connect. Thus, the end face of the first gasket 4 and 5 and the end face of the electrolyte membrane are covered with the end portion of the second gasket 6. The coating is performed all around the periphery.
The electrolyte membrane 1 may be one generally used for a polymer electrolyte fuel cell. For example, a fluorine-based electrolyte membrane or a hydrocarbon electrolyte membrane can be suitably used, and a fluorine-based electrolyte membrane is particularly desirable.

  Similarly, the catalyst layers 2 and 3 may be those generally used for polymer electrolyte fuel cells. For example, a conductive material such as carbon black in which fine particles of platinum or an alloy of platinum and another metal (for example, Ru, Rh, Mo, Cr, Co, Fe, etc.) (the average particle diameter is preferably 10 nm or less) is supported on the surface. A catalyst layer formed from an ink in which carbonaceous fine particles (average particle size: about 20 to 100 nm) and a polymer solution such as a perfluorosulfonic acid resin solution are uniformly mixed in a suitable solvent (such as ethanol) Can be used.

The first gaskets 4 and 5 are made of biaxially stretched polyethylene naphthalate. Thus, the first gaskets 4 and 5 are made of a thermoplastic resin film. The thermoplastic resin film is biaxially stretched so that the molecular orientation is uniform, and the strength, chemical resistance, and heat resistance are excellent. Polyethylene naphthalate is a general-purpose film excellent in gas barrier properties, mechanical strength, and chemical resistance.
For the second gasket 6, a silicone-based or epoxy-based adhesive, or polyethylene naphthalate laminated with a thermoplastic resin such as polyethylene or polypropylene can be used.

Next, the manufacturing method of the membrane electrode assembly in the polymer electrolyte fuel cell according to the embodiment of the present invention will be described.
First, the catalyst layers 2 and 3 are formed on the electrolyte membrane 1. In forming the catalyst layers 2 and 3, an ink containing the polymer electrolyte membrane 1, a catalyst material, a carbon carrier supporting the catalyst, and a dispersion medium is prepared. The prepared catalyst ink is applied onto the electrolyte membrane 1 by using a doctor blade method, a dipping method, a screen printing method, a roll coating method, a spraying method or the like, or a spray method, and a catalyst layer is formed on the electrolyte membrane 1 2 and 3 are formed. Alternatively, a transfer substrate may be used, a catalyst ink may be applied on the transfer substrate, a catalyst layer may be formed on the transfer substrate, and then the catalyst layers 2 and 3 may be formed on the electrolyte membrane 1 by a transfer method. good.

Next, the first gaskets 4 and 5 are disposed on both surfaces of the electrolyte membrane 1 around the formed catalyst layers 2 and 3. The electrolyte membrane 1 is sandwiched between biaxially stretched polyester naphthalates that form the first gaskets 4 and 5 of the present embodiment.
Furthermore, it is arranged on the outer peripheral side. Specifically, the electrolyte membrane 1, the catalyst layers 2 and 3, and the upper and lower first gaskets 4 and 5 are accommodated in between, so that one second The gasket 6 is folded back. Thus, the second gasket 6 is laminated on the upper and lower first gaskets 4 and 5 respectively. Further, the upper and lower second gaskets 6 are pressed against and bonded to the first gaskets 4 and 5. Adhesion may be performed by using an adhesive or by melting and melting a molten resin. Further, the end portions of the second gaskets 6 stacked on the upper and lower sides are also bonded and connected to each other, and the entire outer periphery of the unconnected end portions of the upper and lower second gaskets 6 are also connected.

  For example, referring to FIG. 3, the strip-shaped gasket 7 is folded and placed on a CCM 8 before cutting, which is a catalyst coated membrane (CCM) on which the first gasket is laminated, and pressed with a roller. Glue. At this time, when the welding resin is used as the adhesive layer, it is heated with a heater. Thereafter, the pre-cut CCM 8 is cut, and the obtained post-cut CCM 9 conveyance direction is changed. Next, the folded strip-like gasket 7 is disposed on the remaining side portion of the CCM 9 after cutting, and the second gasket 6 is laminated on the CCM on which the first gasket is laminated by pressing and bonding with a roller. When the strip-shaped gasket 7 is disposed on the CCM 9 after cutting, the strip-shaped gasket 7 is cut as necessary according to the size of the CCM 9 after cutting, and the size is adjusted.

Hereinafter, the membrane electrode assembly 10 and the manufacturing method thereof in the polymer electrolyte fuel cell of the present invention will be described with specific examples, but the present invention is not limited to the examples.
A platinum-supported carbon catalyst having a platinum loading of 60% and Nafion (registered trademark, manufactured by DuPont), which is a 20% by mass polymer electrolyte solution, were mixed with a water / ethanol mixed solvent having a mixing ratio of 1: 2. Subsequently, a dispersion treatment was performed with a planetary ball mill to prepare a catalyst ink.

The transfer sheet was fixed on the plate, and the catalyst ink was applied onto the transfer sheet with a doctor blade. The transfer sheet on which a coating film made of catalyst ink is formed is placed in an oven (hot air circulating constant temperature dryer 41-S5H / Satake Chemical Machinery Co., Ltd.), and the oven temperature is set to 50 ° C. and dried for 5 minutes. A catalyst layer was produced on the sheet. At this time, the platinum loading was adjusted so that the cathode catalyst layer 2 was about 0.5 mg / cm ² and the anode catalyst layer 3 was about 0.3 mg / cm ² .

^Two transfer sheets on which the catalyst layer was formed were cut into 25 cm ² squares, and placed on both surfaces of the electrolyte membrane 1 so that the catalyst layers faced each other. As the electrolyte membrane 1, Nafion 211 (manufactured by DuPont) was used. Subsequently, hot pressing was performed under the conditions of 130 ° C. and 6.0 MPa, and only the transfer substrate was peeled off.
As the first gaskets 4 and 5, 25 cm ² windows are cut out from ^two 35 μm square polyethylene naphthalates, and arranged in accordance with the shapes of the catalyst layers 2 and 3 on the electrolyte membrane 1 so as to face each other. Subsequently, the second gasket 6 in which a silicone-based adhesive was applied to polyethylene naphthalate was folded, and the end surfaces of the electrolyte membrane 1 and the first gaskets 4 and 5 were covered with the end portions of the second gasket 6.

  The fuel cell is sandwiched between MPL-treated carbon paper (manufactured by Toray Industries, Inc.), a gas diffusion layer having a larger area than both catalyst layers, a PEN film having a thickness of 150 μm, and a separator having a gas flow path on both surfaces of the membrane assembly. A single cell was created. When hydrogen gas was supplied from the anode side of the single cell and nitrogen gas was supplied from the cathode side and a leak check was performed, no gas leak was confirmed.

  INDUSTRIAL APPLICABILITY The present invention can be suitably used for a polymer electrolyte fuel cell single cell or a stack in a polymer electrolyte fuel cell, particularly a fuel cell automobile or a household fuel cell.

DESCRIPTION OF SYMBOLS 1 ... Electrolyte membrane 2 ... Cathode catalyst layer 3 ... Anode catalyst layer 4, 5 ... 1st gasket 6 ... 2nd gasket 7 ... Strip-shaped gasket 8 ... CCM before cutting
9 ... CCM after cutting
10 ... Membrane electrode assembly

Claims (8)

In a membrane electrode assembly having an electrolyte membrane, a cathode catalyst layer disposed on one surface side of the electrolyte membrane, and an anode catalyst layer disposed on the other surface side of the electrolyte membrane,
Each gasket layer disposed on the electrolyte membrane at the outer periphery of each catalyst layer,
Each gasket layer has a first gasket on the electrolyte membrane side and a second gasket laminated thereon,
The second gasket on the cathode catalyst layer side and the second gasket on the anode catalyst layer side are made continuous ,
A membrane electrode assembly , wherein the thickness of each gasket layer comprising the first gasket and the second gasket is equal to the thickness of each catalyst layer on the side where the gasket is disposed . The membrane electrode assembly according to claim 1, wherein the first gasket is made of a single layer thermoplastic resin film. Said second gasket, membrane electrode assembly according to claim 1 or claim 2, characterized in that a thermoplastic resin film having an adhesive layer. The membrane electrode assembly according to any one of claims 1 to 3 , wherein both the first and second gaskets are polyester resins. The membrane electrode assembly according to any one of claims 1 to 4 , wherein both the first and second gaskets are biaxially stretched polyethylene naphthalate. The membrane electrode according to any one of claims 1 to 5 , wherein the second gasket has a base film coated with a resin that melts at 100 ° C or higher, or a heat-resistant adhesive layer. Joined body. An electrolyte membrane, a cathode catalyst layer disposed on one surface side of the electrolyte membrane, an anode catalyst layer disposed on the other surface side of the electrolyte membrane, and an outer periphery of each catalyst layer on the electrolyte membrane Each gasket layer to be disposed,
Each gasket layer has a first gasket on the electrolyte membrane side and a second gasket laminated thereon,
A second gasket made wider than the first gasket at the end of the second gasket is covered with the end face of the first gas Ke Tsu DOO end face and the electrolyte membrane,
A membrane electrode assembly , wherein the thickness of each gasket layer comprising the first gasket and the second gasket is equal to the thickness of each catalyst layer on the side where the gasket is disposed . An electrolyte membrane, a cathode catalyst layer disposed on one surface side of the electrolyte membrane, an anode catalyst layer disposed on the other surface side of the electrolyte membrane, and an outer periphery of each catalyst layer on the electrolyte membrane Each gasket layer to be disposed,
Each gasket layer has a first gasket on the electrolyte membrane side and a second gasket laminated thereon,
The second gasket is set wider than the first gasket, in the end of the second gasket is covered with the end face of the first gas Ke Tsu DOO end face and the electrolyte membrane,
It said first gasket and the second method for manufacturing a the thickness of each gasket layer made of the gasket, characterized by equal to Rukoto the thickness of each catalyst layer on the side which is arranged a membrane electrode assembly.

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