JP5463624B2 - Method for producing membrane / electrode assembly for polymer electrolyte fuel cell - Google Patents

Description

  The present invention relates to a method for producing a membrane / electrode assembly for a polymer electrolyte fuel cell.

  Of the membrane / electrode assembly for a polymer electrolyte fuel cell constituting the polymer electrolyte fuel cell (hereinafter, also simply referred to as “membrane / electrode assembly”), it is disposed on both main surfaces of the electrolyte membrane. A catalyst layer (that is, a catalyst layer / electrolyte membrane / catalyst layer structure) is called a three-layer MEA, and electrode substrates are provided on both main surface sides of the three-layer MEA. An arrangement (that is, a layer structure of electrode substrate / catalyst layer / electrolyte membrane / catalyst layer / electrode substrate) is referred to as a five-layer MEA.

In order to improve the performance of a polymer electrolyte fuel cell, optimization of the structure of the membrane / electrode assembly is the key. Examples of the method for producing a membrane / electrode assembly include the following methods (1) to (3).
(1) A method for forming a catalyst layer on an electrode substrate, also called a gas diffusion layer (GDL), by coating (2) A decal method (a method for transferring a catalyst layer formed on a film to an electrolyte membrane)
(3) Method of directly applying catalyst-containing paste to the electrolyte membrane

  In the method (1), since the catalyst-containing paste is applied to the porous GDL, there are problems such as waste of the catalyst due to the penetration of the catalyst into the GDL and a decrease in the gas permeability of the GDL. In method (2), a catalyst layer is formed on a film having a stable shape by coating, and then the catalyst layer is transferred to the electrolyte membrane by hot pressing, so that a catalyst layer having a uniform pore structure can be formed. The electrolyte membrane may be damaged by the press, and the long-term durability of the cell may not be ensured. In addition, depending on the type of catalyst, there are some which are difficult to transfer, and in that case, the problem is that the yield during mass production is low. In the method (3), since the catalyst-containing paste is directly applied to the electrolyte membrane, the number of steps can be reduced as compared with other methods. Moreover, since the electrolyte membrane does not dent due to pressing, it is considered that the long-term durability of the cell can be secured. However, when a perfluorosulfonic acid electrolyte membrane such as a Nafion (registered trademark) membrane generally used as an electrolyte membrane is used, the electrolyte membrane swells significantly due to the solvent in the catalyst-containing paste, and a good electrolyte There is a problem that a membrane-electrode assembly provided with a membrane cannot be obtained.

  Further, Patent Documents 1 to 3 disclose other methods for producing a membrane / electrode assembly.

In Patent Document 1, in order to avoid the swelling of the electrolyte membrane, a normal proton type electrolyte membrane is converted into a Na ⁺ type that is stable with respect to the solvent contained in the catalyst-containing paste, and then the catalyst-containing paste is used. A method of coating the electrolyte membrane is disclosed. Patent Document 2 discloses a method of forming a catalyst layer by directly applying an electrocatalyst coating composition to an electrolyte membrane supported by a dimensionally stable substrate. Patent Document 3 discloses the following method. First, a mask film partially cut out corresponding to the electrode shape is applied to one surface of the electrolyte membrane, and a mask film provided with a weakened line corresponding to the electrode shape is applied to the other surface of the electrolyte membrane. Affix by thermocompression bonding. Next, the first catalyst layer is formed by applying a cathode paste using a mask film, a part of which is cut out corresponding to the electrode shape, as a mask. Next, the mask film surrounded by the weakening line is peeled off, and an anode paste is applied on the exposed electrolyte membrane to form a second catalyst layer.
Registration No. 3554321 JP-T-2006-507623 JP 2006-120433 A

However, in the method described in Patent Document 1, the electrolyte membrane converted to the Na ⁺ type must be returned to the proton type by treatment with a strong acid solution before use of the membrane-electrode assembly.

  In the method described in Patent Document 2, there is no problem in forming the first catalyst layer by directly applying the electrocatalyst coating composition to the first surface of the electrolyte membrane disposed on the first temporary substrate. . However, the formation of the second catalyst layer is performed after first pressing the second temporary substrate against the first catalyst layer using a low-pressure laminator including a pair of rolls, and then peeling the first temporary substrate from the electrolyte membrane. Therefore, the electrolyte membrane may be damaged. In addition, the second surface of the electrolyte membrane (opposite of the first surface) in a state where a gap exists between the periphery of the portion of the surface of the second temporary substrate in contact with the first catalyst layer and the first surface of the electrolyte membrane. Since the second catalyst layer is formed by directly applying the electrocatalyst coating composition to the surface), there is a possibility that the portion in the vicinity of the void in the electrolyte membrane swells.

  In the method described in Patent Document 3, a mask film partially cut out corresponding to the electrode shape is attached to one surface of the electrolyte membrane by thermocompression bonding. Therefore, the mask film on one surface of the electrolyte membrane There is a possibility that the portion in contact with the dent will dent and damage the electrolyte membrane. In addition, a battery such as long-term durability, which is contained in the tack resin layer constituting the mask film and has a part of the styrene-ethylene-butadiene copolymer having low heat resistance and low acid resistance, is transferred to the second catalyst layer. May adversely affect properties.

  The present invention provides a membrane / electrode assembly for a polymer electrolyte fuel cell that can form a catalyst layer having a homogeneous pore structure while suppressing damage due to mechanical load applied to the electrolyte membrane and swelling of the electrolyte membrane. A manufacturing method is provided. In addition, the present invention provides a membrane / electrode assembly for a polymer electrolyte fuel cell that has high uniformity in the thickness of the electrolyte membrane, good performance, and long-term stability.

The method for producing a membrane / electrode assembly for a polymer electrolyte fuel cell according to the present invention comprises:
A first catalyst-containing paste is applied to the surface of the electrolyte membrane fixed on the first substrate opposite to the surface on the first substrate side, and then the first catalyst-containing paste applied to the electrolyte membrane is dried. A first catalyst layer forming step,
The first catalyst layer and the second substrate having rubber-like elasticity are in contact with each other, and a gap is formed between the second substrate and the laminate including the first catalyst layer, the electrolyte membrane, and the first substrate. Without causing the laminate to be fixed to the second substrate, a second catalyst-containing paste is applied to the surface of the electrolyte membrane opposite to the surface on which the first catalyst layer is formed, And a second catalyst layer forming step of drying the second catalyst-containing paste applied to the electrolyte membrane.

The membrane / electrode assembly for a polymer electrolyte fuel cell of the present invention is a membrane / electrode assembly for a polymer electrolyte fuel cell formed by the method for producing a membrane / electrode assembly for a polymer electrolyte fuel cell of the present invention. Body,
The electrolyte membrane;
A first catalyst layer disposed in contact with one main surface of the electrolyte membrane;
A second catalyst layer disposed in contact with the other main surface of the electrolyte membrane,
Of the electrolyte membrane, at least one and contact portions of said first catalyst layer and the second catalyst layer, the thickness of the thickest portion and T _1, when the thickness of the thinnest portion and T _2,
T ₂ is 80% or more of T ₁ .

  According to the present invention, a membrane / electrode joint for a polymer electrolyte fuel cell that can form a catalyst layer having a homogeneous pore structure while suppressing damage due to a mechanical load applied to the electrolyte membrane and swelling of the electrolyte membrane. A method of manufacturing a body can be provided. Further, according to the present invention, it is possible to provide a membrane / electrode assembly for a polymer electrolyte fuel cell having high uniformity in the thickness of the electrolyte membrane, good performance, and long-term stability.

  FIG. 1 is a schematic cross-sectional view of an example of a membrane / electrode assembly produced by the method for producing a membrane / electrode assembly of the present invention, and FIG. 2 constitutes the membrane / electrode assembly shown in FIG. It is a schematic cross section of 3 layer MEA. An example of the membrane / electrode assembly of the present invention described with reference to FIG. 1 is a five-layer MEA, but the membrane / electrode assembly of the present invention also includes a three-layer MEA.

  As shown in FIGS. 1 and 2, a fuel electrode 6 composed of a first catalyst layer 4 and a first electrode substrate 5 is disposed on one main surface of the electrolyte membrane 1, and the other main surface of the electrolyte membrane 1. An air electrode 8 composed of the second catalyst layer 4 ′ and the second electrode base material 7 is disposed thereon. By disposing a ribbed separator and a current collector plate (not shown) in this order on both principal surface sides of the laminate comprising the electrolyte membrane 1, the fuel electrode 6 and the air electrode 8, a single cell (fuel cell) ) Is configured. Protons flow from the fuel electrode 6 through the electrolyte membrane 1 to the air electrode 8. Further, electrons flow from the fuel electrode 6 to the air electrode 8 through an external circuit. As a result, electricity flows between the fuel electrode 6 and the air electrode 8. Hereinafter, the first catalyst layer 4 and the second catalyst layer 4 ′ may be collectively referred to as “catalyst layer”.

  Next, a method for manufacturing the membrane-electrode assembly shown in FIG. 1 will be described with reference to FIG.

  As shown in FIG. 3A, first, a laminate in which the electrolyte membrane 1 is directly fixed on the first substrate 2 is prepared. Next, as shown in FIG. 3B, the first catalyst-containing paste is applied to the surface opposite to the surface on the first substrate 2 side of the electrolyte membrane 1, and then the first catalyst-containing material applied to the electrolyte membrane 1 is applied. The paste is dried to obtain the first catalyst layer 4 (first catalyst layer forming step).

  Next, as shown in FIG. 3C, the first catalyst layer 4 and the second substrate 3 having rubber-like elasticity are in contact with each other, and the first catalyst layer 4, the electrolyte membrane 1, and the first substrate 2 are stacked. The laminated body 10 is fixed to the second substrate 3 without generating a gap between the body 10 and the second substrate 3. That is, by elastically deforming the second substrate 3, the surface of the stacked body 10 facing the second substrate 3 and the surface of the second substrate 3 facing the stacked body 10 are brought into close contact with each other without generating a gap. When the first substrate 3 and the electrolyte membrane 1 are long belt-like sheets and a plurality of first catalyst layers are formed on the electrolyte membrane 1 at predetermined intervals, the adjacent first catalyst layers are elastically deformed. The stacked body 10 is brought into close contact with the second substrate 3 so as to be filled with a part of the second substrate 3.

  Next, the first substrate 2 is peeled from the electrolyte membrane 1 (see FIG. 3D). Next, as shown in FIG. 3E, the second catalyst-containing paste is applied to the surface opposite to the surface on which the first catalyst layer 4 of the electrolyte membrane 1 is formed, and then the second coating applied to the electrolyte membrane 1 is performed. The 2 catalyst-containing paste is dried to form the second catalyst layer 4 ′ (second catalyst layer forming step). Next, the 2nd board | substrate 3 is peeled from the 1st catalyst layer 4, and 3 layer MEA is obtained. Subsequently, the membrane electrode assembly (5-layer MEA) is obtained by bonding the first electrode base material 5 and the second electrode base material 7 to both main surface sides of the 3-layer MEA by a known method.

  Both the first catalyst layer 4 and the second catalyst layer 4 ′ contain carbon particles carrying catalyst particles (catalyst-carrying carbon particles) and a hydrogen ion conductive polymer electrolyte. Examples of the catalyst particles include platinum and platinum compounds. Examples of the platinum compound include an alloy of platinum and at least one metal selected from the group consisting of ruthenium, palladium, nickel, molybdenum, iridium, iron, cobalt, and the like. The catalysts contained in the first catalyst layer 4 and the second catalyst layer 4 'may be the same or different.

  Examples of the hydrogen ion conductive polymer electrolyte include perfluorosulfonic acid-based fluorine ion exchange resins. The mixing ratio of the catalyst-supporting carbon particles and the hydrogen ion conductive polymer electrolyte is preferably 1: 0.1 to 1: 1 by weight ratio of the solid content, and is preferably 1: 0.2 to 1: 0.5. More preferably.

  To form the first catalyst layer 4 or the second catalyst layer 4 ′, the first catalyst-containing paste obtained by mixing and dispersing the catalyst-supporting carbon particles and the hydrogen ion conductive polymer electrolyte in an appropriate solvent, or A second catalyst-containing paste is used.

  Examples of the solvent include various alcohols, various ethers, various dialkyl sulfoxides, water, or a mixture thereof.

  The application of the first catalyst-containing paste and the second catalyst-containing paste is not particularly limited. For example, knife coater, bar coater, spray, dip coater, spin coater, roll coater, die coater, curtain coater, screen A general method such as printing can be applied.

  The thicknesses of the first catalyst layer 4 and the second catalyst layer 4 ′ are usually preferably 10 to 50 μm and more preferably 15 to 30 μm.

  As the electrolyte membrane 1, known ones can be used. For example, perfluorosulfonic acid-based fluorine ion exchange resin membranes, more specifically, C—H bonds of hydrocarbon-based ion exchange membranes with fluorine are used. Examples include membranes made of proton conductive polymer electrolytes such as substituted perfluorocarbon sulfonic acid polymers (PFS polymers). By introducing a fluorine atom having high electronegativity, it is chemically very stable, the dissociation degree of the sulfonic acid group is high, and high ion conductivity can be realized. Specific examples of such a proton conductive polymer electrolyte membrane include, for example, “Nafion” (registered trademark) manufactured by DuPont, “Flemion” (registered trademark) manufactured by Asahi Glass Co., Ltd., and manufactured by Asahi Kasei Corporation. “Aciplex” (registered trademark), “Gore Select” (registered trademark) manufactured by Gore, and the like.

  The thickness of the electrolyte membrane used for the production of the membrane / electrode assembly is usually preferably 20 to 250 μm and more preferably 20 to 80 μm.

  The first substrate 2 that supports the electrolyte membrane 1 is not particularly limited as long as the first catalyst layer 4 can be formed without causing deformation due to a mechanical load or the like to the electrolyte membrane 1, but for example, polyethylene terephthalate , Polyethylene, polypropylene, nylon, polyimide, polytetrafluoroethylene (PTFE), resin sheets containing a resin such as tetrafluoroethylene / hexafluoropropylene copolymer (FEP), or a sheet-like rubber-like elastic body. Can be mentioned. In particular, when the electrolyte membrane 1 is formed on the first substrate 2 by cast molding, among the above resins, polyethylene terephthalate, polyimide, etc. excellent in chemical stability, chemical resistance, and heat resistance are used. desirable. When fixing the already formed electrolyte membrane to the first substrate 2, a rubber-like elastic body is desirable in addition to the resin sheet. Examples of the material for the rubber-like elastic body include the same materials as those for the second substrate described later.

  Although there is no restriction | limiting in particular about the thickness of the 1st board | substrate 2, Usually 10 micrometers-100 micrometers are preferable, and 20 micrometers-60 micrometers are more preferable, since a handleability is favorable and the adaptation to a Roll to Roll corresponding | compatible winding apparatus is favorable.

  As the 2nd board | substrate 3, what contains a rubber-like elastic body is used. Examples of the rubber-like elastic material include natural rubber, styrene rubber, butyl rubber, chloroprene rubber, silicon rubber, urethane rubber, fluorine rubber, acrylic rubber, nitrile rubber, and styrene butadiene rubber. In particular, it does not generate degradation products even when in contact with a chemically active catalyst layer, and does not degrade battery performance and durability due to migration of degradation products to the catalyst layer. Silicon rubber or fluorine rubber is more preferable. The second substrate 3 may be entirely made of a rubber-like elastic body, but may be a laminate of a sheet-like rubber-like elastic body and a film. Further, when the second substrate 3 includes silicon rubber or fluororubber, the whole may be formed of silicon rubber or fluororubber, but at least the first catalyst layer 4 of the laminate 10 of the second substrate 3 and It is only necessary that the contacting surface contains silicon rubber or fluorine rubber.

  20-80 are preferable and, as for the rubber hardness measured based on JISK6253 of the 2nd board | substrate 3, it is more preferable in it being 40-60. When the hardness of the second substrate 3 is 20 to 80, the second substrate 3 has an appropriate tack property that allows the electrolyte membrane 1 to be fixed to the second substrate 3 and good for the uneven surface that the second substrate 3 is in contact with. It is possible to combine the following ability. Further, when the hardness of the second substrate 3 is 20 to 80, the electrolyte membrane 1 is peeled off from the second substrate 3 even if tension is generated in the electrolyte membrane coated with the second catalyst-containing paste. And generation of wrinkles can be prevented.

  A well-known thing can be used as a 1st electrode base material and a 2nd electrode base material. For example, a porous conductive substrate that can efficiently supply fuel gas or the like as fuel to the first catalyst layer 4 and the second catalyst layer 4 ′, more specifically, carbon paper or carbon cloth is used. be able to.

  The thickness of the second substrate 3 is preferably 20 μm to 1000 μm, preferably 50 μm to 300 μm, because it is easy to handle and adapts well to a roll-to-roll winding device and has a high cushioning property. More preferred.

  The electrolyte membrane 1 may be fixed to the first substrate 2 by forming the electrolyte membrane 1 on the first substrate 2 by casting, or the first substrate 2 may be a rubber-like elastic body, for example. In some cases, it may be performed by the tackiness of the rubber-like elastic body. The electrolyte membrane 1 can be cast by applying a solution containing the proton conductive polymer electrolyte on the first substrate 2 and drying the applied solution containing the proton conductive polymer electrolyte. The concentration of the proton conductive polymer electrolyte contained in the solution is usually preferably 5 to 60% by weight and more preferably 20 to 40% by weight.

  The electrolyte membrane 1 is fixed to the second substrate 3 by the tackiness of the second substrate 3 having rubber-like elasticity. For example, when hot pressing is performed, wrinkles are generated in the electrolyte membrane around the catalyst layer due to the difference in thermal contraction rate between the catalyst layer and the electrolyte membrane. It causes poor contact and causes a reduction in durability. If the laminated body 10 is fixed to the second substrate 3 by pressure bonding without applying heat using the tack property, the occurrence of the above-described problem due to the difference in thermal shrinkage rate can be prevented.

The electrolyte membrane 1 can be fixed to the first substrate 2 by, for example, a roll press or a plane press. Further, the laminate 10 can be fixed to the second substrate 3 by a roll press or a plane press. The pressure applied to the electrolyte membrane 1 during these fixations is preferably 0.01 to 5 kgf / cm ² .

  In the method for producing a membrane / electrode assembly according to the present invention, the laminate 10 is formed without causing a gap between the laminate 10 and the second substrate 3 composed of the first catalyst layer, the electrolyte membrane, and the first substrate. After fixing to the second substrate 3, the second catalyst-containing paste is applied to the surface opposite to the surface on which the first catalyst layer 4 of the electrolyte membrane 1 is formed. Swelling of the resulting electrolyte membrane is suppressed. Moreover, since the 2nd board | substrate 3 has rubber-like elasticity, the damage by the mechanical load which the electrolyte membrane 1 receives is also suppressed. Therefore, the thickness uniformity of the electrolyte membrane constituting the membrane / electrode assembly produced by the method for producing a membrane / electrode assembly of the present invention is high.

Specifically, for example, as shown in FIG. 4, the thickness of the thickest portion of the electrolyte membrane 1 in contact with at least one of the first catalyst layer 4 and the second catalyst layer 4 is T _When the thickness of the thinnest portion is T ₂ , T ₂ is 80% or more of T ₁ , preferably 90% or more, and more preferably 95% or more. Since the penetration of the catalyst layer into the electrolyte membrane 1 is likely to occur at the peripheral portion of the catalyst layer, in general, T ₂ is often the thickness of the portion of the electrolyte membrane 1 in contact with the peripheral portion of the catalyst layer. In the portion of the electrolyte membrane 1 that is in contact with the catalyst layer, if there is an extremely thin portion, the deterioration reaction concentrates on the thin portion when long-term operation is performed, and the deterioration of the cell is promoted. there is a possibility.

In an example of the membrane / electrode assembly of the present invention, T ₂ is 80% or more of T ₁ , and the thickness of the electrolyte membrane is highly uniform. And a long-term stable polymer electrolyte fuel cell can be provided.

  EXAMPLES The present invention will be described in more detail with reference to examples below, but the present invention is not limited to these examples.

[Example 1]
An electrolyte membrane cast on a PET substrate (NAFION212CS, manufactured by DuPont) is overlaid with a tencil mask partially cut out corresponding to the planar shape of the first catalyst layer, and the following composition is formed on the exposed portion of the electrolyte membrane. After applying the catalyst-containing paste by spraying, the applied catalyst-containing paste was air-dried (room temperature) to form a first catalyst layer (thickness 32 μm). The catalyst-containing paste was applied so that the amount of Pt supported was 0.5 mg / cm ² .
[Composition of catalyst-containing paste]
Catalyst (TEC10E70TPM, Tanaka Kikinzoku Co., Ltd.) 1 part by weight electrolyte (nafionDE2020 CS) 0.25 part by weight water 2 parts by weight n-butanol 6 parts by weight

Next, a silicon rubber substrate (thickness: 200 μm, rubber hardness: 55 (JIS K 6253), manufactured by Mitsubishi Plastics Co., Ltd.) is placed on a laminate composed of a first catalyst layer, an electrolyte membrane and a PET substrate (<0 0.1 kgf / cm ² ), the PET substrate was peeled from the electrolyte membrane after being pressure-bonded at room temperature. Next, on the surface opposite to the surface on which the first catalyst layer of the electrolyte membrane is formed, a part thereof is cut out corresponding to the planar shape of the second catalyst layer, and a tencil mask is disposed. After coating by spraying, the coated catalyst-containing paste was air-dried to form a second catalyst layer (thickness 32 μm). The catalyst-containing paste was applied so that the amount of Pt supported was 0.5 mg / cm ² . In this way, a three-layer MEA was obtained. The thickness of the silicon rubber substrate was measured using a digital meter M-30 (manufactured by Sony Corporation).

[Comparative Example 1]
Instead of pressure bonding the silicon rubber substrate to the laminate, a PET substrate (Lumirror X-S10, thickness 200 μm, manufactured by Toray Industries, Inc.) is thermocompression bonded (100 ° C., 30 kgf / cm ² ) to the laminate. A three-layer MEA was obtained in the same manner as in Example 1 except that.

[Comparative Example 2]
After spraying the catalyst-containing paste used in Example 1 on a PET film (Lumirror X43, thickness 50 μm, manufactured by Toray Industries, Inc.), the applied catalyst-containing paste was air-dried (room temperature), One catalyst layer (thickness 30 μm) was formed. The catalyst-containing paste was applied so that the amount of Pt supported was 0.5 mg / cm ² . In addition, the catalyst-containing paste applied after spraying the catalyst-containing paste used in Example 1 on a PET film (Lumirror X43, thickness 50 μm, manufactured by Toray Industries, Inc.) different from the above PET film. Was air-dried (room temperature) to form a second catalyst layer (thickness 30 μm). The catalyst-containing paste was applied so that the amount of Pt supported was 0.5 mg / cm ² . Next, a first catalyst layer is arranged on one main surface of the electrolyte membrane (NAFION212CS, manufactured by DuPont), and a second catalyst layer is arranged on the other main surface, respectively, and a press machine (press plate temperature: 130 ° C.). To obtain a three-layer MEA.

Conceptual images of SEM (scanning electron microscope) photographs of cross sections of the three-layer MEA of Examples and Comparative Examples are shown in FIGS. In FIGS. 4 to 6, hatching is omitted for easy understanding of the drawings. Samples were prepared as follows, and SEM observation conditions were as follows.
[Sample preparation]
The three-layer MEAs of Examples and Comparative Examples were resin-sealed with an epoxy resin, and the cross-section was formed by polishing the sealing resin and the three-layer MEA so that the cross-section of the three-layer MEA could be observed.
[SEM observation conditions]
The cross section was observed at a magnification of 100 using an electron microscope JIB-4500 (manufactured by JEOL Ltd.).

[Measurement of electrolyte membrane thickness]
As shown in FIGS. 4 to 6, the thickness of the portion in contact with the peripheral portion of the first catalyst layer or the second catalyst layer (at least one of the first catalyst layer and the second catalyst layer in the electrolyte membrane) in the portion in contact with, the thinnest portion of the thickness) T _2, of the first catalyst layer and the second central portion and contact portion of the thickness of the catalyst layer (the electrolyte membrane, the first catalyst layer and the second catalyst The thickness (thickness of the thickest portion) T ₁ in a portion in contact with at least one of the layers was obtained by conversion from a value measured from a cross-sectional SEM photograph (100 times). In addition, five samples were prepared for each of Example 1, Comparative Example 1, and Comparative Example 2. T ₁ and T ₂ are average values of 5 samples. T ₁ and T ₂ are shown in Table 1.

As shown in Table 1, in the three-layer MEA of Example 1, T ₂ and T ₁ were hardly changed, and T ₂ was 80% or more of T ₁ . On the other hand, in the three-layer MEA of Comparative Example 1 and Comparative Example 2, T ₂ was much smaller than T ₁ and T ₂ was less than 80% of T ₁ .

  According to the method for producing a membrane / electrode assembly of the present invention, a catalyst layer having a uniform pore structure can be formed while suppressing damage due to mechanical load applied to the electrolyte membrane and swelling of the electrolyte membrane. A method for producing a membrane / electrode assembly is useful. In addition, since the membrane / electrode assembly of the present invention produced by the method of manufacturing a membrane / electrode assembly of the present invention has good uniformity in the thickness of the electrolyte membrane, the membrane / electrode assembly of the present invention can be used. Thus, it is possible to provide a polymer electrolyte fuel cell with good performance and long-term stability.

FIG. 1 is a schematic cross-sectional view of an example of the membrane / electrode assembly of the present invention. 2 is a schematic cross-sectional view of a three-layer MEA constituting the membrane-electrode assembly shown in FIG. 3A to 3F are process schematic cross-sectional views illustrating an example of a method for producing a membrane / electrode assembly of the present invention. 4 is a conceptual diagram of a SEM photograph of a cross section of the membrane / catalyst layer assembly of Example 1. FIG. FIG. 5 is a conceptual diagram of an SEM photograph of a cross section of the membrane / catalyst layer assembly of Comparative Example 1. 6 is a conceptual diagram of an SEM photograph of a cross section of the membrane / catalyst layer assembly of Comparative Example 2. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electrolyte membrane 4 1st catalyst layer 4 '2nd catalyst layer 5 1st electrode base material 7 2nd electrode base material 8 Fuel electrode 6 Air electrode 2 1st board | substrate 3 2nd board | substrate 10 laminated body

Claims (7)

A first catalyst-containing paste is applied to the surface of the electrolyte membrane fixed on the first substrate opposite to the surface on the first substrate side, and then the first catalyst-containing paste applied to the electrolyte membrane is dried. A first catalyst layer forming step,
The first catalyst layer and the second substrate having rubber-like elasticity are in contact with each other, and a gap is formed between the second substrate and the laminate including the first catalyst layer, the electrolyte membrane, and the first substrate. Without causing the stack to be fixed to the second substrate, the first substrate is peeled from the electrolyte membrane, and the surface of the electrolyte membrane opposite to the surface on which the first catalyst layer is formed, Applying a second catalyst-containing paste, and then drying the second catalyst-containing paste applied to the electrolyte membrane, and forming a second catalyst layer, and a membrane / electrode for a polymer electrolyte fuel cell Manufacturing method of joined body.   The method for producing a membrane / electrode assembly for a polymer electrolyte fuel cell according to claim 1, wherein the rubber hardness of the second substrate measured in accordance with JIS K 6253 is 20-80.   3. The method for producing a membrane / electrode assembly for a polymer electrolyte fuel cell according to claim 1, wherein a surface of the second substrate in contact with the laminate includes silicon rubber or fluorine rubber.   4. The method for producing a membrane / electrode assembly for a polymer electrolyte fuel cell according to claim 1, wherein the thickness of the second substrate is 20 μm to 1000 μm.   The membrane / electrode joint for a polymer electrolyte fuel cell according to any one of claims 1 to 4, wherein in the second catalyst layer forming step, the laminate is fixed to the second substrate by pressure bonding without applying heat. Body manufacturing method.   The method for producing a membrane-electrode assembly for a polymer electrolyte fuel cell according to any one of claims 1 to 5, wherein the first substrate is a rubber-like elastic body. A membrane / electrode assembly for a polymer electrolyte fuel cell formed by the method for producing a membrane / electrode assembly for a polymer electrolyte fuel cell according to any one of claims 1 to 6,
The electrolyte membrane;
A first catalyst layer disposed in contact with one main surface of the electrolyte membrane;
A second catalyst layer disposed in contact with the other main surface of the electrolyte membrane,
Of the electrolyte membrane, at least one and contact portions of said first catalyst layer and the second catalyst layer, the thickness of the thickest portion and T _1, when the thickness of the thinnest portion and T _2, A membrane / electrode assembly for a polymer electrolyte fuel cell, wherein T ₂ is 80% or more of T ₁ .

Images