JP4810841B2 - Method and apparatus for producing electrolyte membrane-catalyst layer assembly for polymer electrolyte fuel cell - Google Patents

Description

  The present invention relates to a method and an apparatus for producing an electrolyte membrane-catalyst layer assembly for a polymer electrolyte fuel cell.

  A solid polymer electrolyte fuel cell is composed of a solid polymer membrane having proton conductivity as an electrolyte, and a fuel electrode and an air electrode joined to both sides of the membrane, supplying hydrogen to the fuel electrode and oxygen or air to the air electrode This is a system that generates electricity through an electrochemical reaction. The following reactions occur at each electrode.

The fuel ^{_{electrode: H 2 → 2H + + 2e}} -
Air _{electrode: (1/2) O 2 + 2H} + + 2e - → H 2 O
Total reaction: H ₂ + (1/2) O ₂ → H ₂ O
As can be seen from these reaction equations, only water is generated during power generation. Unlike conventional internal combustion engines, fuel cells are attracting attention as one of the next generation clean energy systems because they do not generate environmentally harmful gases such as carbon dioxide.
The solid polymer electrolyte fuel cell can generate electric power even when methanol is supplied as a fuel. In this case, the polymer electrolyte fuel cell is particularly called a methanol direct fuel cell. The following reactions occur at each electrode.

_{Anode: CH 3 OH + H 2 O} → 6H + + 6e - + CO 2
Air _{electrode: (3/2) O 2 + 6H} + + 6e - → 3H 2 O
All reactions: CH ₃ OH + (3/2) O ₂ → 2H ₂ O + CO ₂
A solid polymer electrolyte fuel cell uses a hydrogen ion (proton) conductive polymer electrolyte membrane as an electrolyte membrane, a catalyst layer is arranged on both sides, an electrode substrate is arranged on both sides, and this is further separated by a separator. It has a sandwiched structure.

  A catalyst layer disposed on both surfaces of an electrolyte membrane (that is, a catalyst layer / electrolyte membrane / catalyst layer structure) is called an electrolyte membrane-catalyst layer assembly, and both surfaces of the electrolyte membrane-catalyst layer assembly. An electrode base material arranged on the substrate (namely, electrode base material / catalyst layer / electrolyte membrane / catalyst layer / electrode base material layer structure) is called an electrolyte membrane-electrode assembly (MEA). Has been.

  In general, the following method is used as a method for producing the electrolyte membrane-electrode assembly.

  (a) A catalyst ink composed of an electrode catalyst and an electrolyte material is directly applied and dried on the electrolyte membrane, and an electrode base material is bonded thereon to produce an electrolyte membrane-electrode assembly.

  (b) An electrolyte membrane-electrode assembly is prepared by bonding the electrode substrate coated with catalyst ink and dried to the electrolyte membrane.

  In general, carbon materials such as carbon paper and carbon cloth are used as the electrode substrate, and methods such as screen printing, spray coating, and spin coating are used for applying the catalyst ink.

  In the case of the above method (a), deformation due to swelling of the electrolyte membrane by the solvent may occur in the direct application of the catalyst ink to the electrolyte membrane. In the case of the above method (b), voids exist on the surface and inside of the electrode base material, and the catalyst ink may permeate into the voids. In any method, it is not easy to produce a flat catalyst layer having a uniform thickness. Furthermore, in the case of the method (b), the clogging of the voids may occur due to the catalyst layer that has entered the inside of the electrode base material, and the supply and discharge of fuel and oxidant may be hindered.

  As a solution for these problems, a method for producing an electrolyte membrane-catalyst layer assembly by a transfer method has attracted attention. In the transfer method, a film for forming a catalyst layer in which a catalyst layer is formed on a base film is prepared, and this is placed on both sides of the electrolyte film so that the catalyst layers face each other, and is subjected to hot press to thereby form an electrolyte membrane. An electrolyte membrane-electrode assembly is produced by forming a catalyst layer thereon and disposing electrode bases on both sides thereof.

  Using such a transfer method, it is possible to mass-produce a homogeneous electrolyte membrane-electrode assembly with high productivity by producing an electrolyte membrane-electrode assembly in-line while producing a film for forming a catalyst layer. It has been proposed (see Patent Document 1).

However, in the catalyst layer transfer method using a pressure roll described in Patent Document 1, an electrolyte membrane-electrode assembly having a desired electrode shape cannot be produced at a desired position on the electrolyte.
Japanese Patent Laid-Open No. 10-64574

  The present invention provides a method and apparatus for producing an electrolyte membrane-catalyst layer assembly having an arbitrarily shaped catalyst layer.

The present inventor has intensively studied to solve the above problems. As a result, the electrolyte membrane and the catalyst layer forming film on which the catalyst layer is formed are opposed to each other through a mask film on which a desired opening is formed, and hot pressing is performed to form the catalyst layer on the catalyst layer forming film. An electrolyte membrane-catalyst layer having a catalyst layer of any shape by winding the joined body of the electrolyte membrane and the catalyst layer forming film without peeling off the mask film and the substrate film It was found that a joined body can be produced. The present invention has been completed based on such findings.

  The mask film preferably has a release layer on the surface in contact with the catalyst layer so that it can be reused.

  According to the method for producing an electrolyte membrane-catalyst layer assembly for a polymer electrolyte fuel cell according to the present invention, the catalyst layer is transferred onto the electrolyte membrane through the opening of the desired shape formed in the mask film, so that it has an arbitrary shape. An electrolyte membrane-catalyst layer assembly having the catalyst layer can be produced. By continuously supplying the electrolyte membrane, the mask film, and the catalyst layer forming film, a large amount can be manufactured continuously with good productivity and efficiency.

  Below, the manufacturing method of the electrolyte membrane-catalyst layer assembly for fuel cells which concerns on this invention is demonstrated with reference to drawings. Throughout the drawings, the same components are denoted by the same reference numerals, and redundant description may be omitted in the following description.

  FIG. 1 is a process diagram conceptually showing a method for producing an electrolyte membrane-catalyst layer assembly for a fuel cell according to the present invention with plan views of each element.

  As shown in FIG. 2, the catalyst layer forming film 1 has a catalyst layer 3 formed on a base film 2. The catalyst layer 3 includes catalyst particles including platinum fine particles and carbon particles, and a proton conductive electrolyte material. A known coating method such as screen printing, spray coating, die coating, and knife coating is applied to the base film 2. It is formed using.

  The base film 2 has heat resistance and strength that can withstand hot pressing, and preferably employs a flexible material. As shown in FIG. 3, a catalyst layer forming film 1 ′ in which a release layer 4 is formed on a base film 2 may be used. The release layer 4 is formed by a known method such as silicon coating, fluorine coating, or plasma treatment.

  The mask film 5 has a desired shape and an opening 6 formed in advance at a desired position. As the mask film 5, for example, a polyethylene terephthalate film, stainless steel, silicon rubber, or the like can be adopted. However, any metal, polymer, rubber, or paper can be used as long as the material has heat resistance and strength that can withstand heat press described later. Any material is acceptable. As shown in FIG. 4, the mask film 5 may have a release layer 7 formed on the surface of the mask film substrate 5 a in contact with the catalyst layer. The release layer 7 can be formed by a known processing method such as plasma processing, silicon coating, or fluorine coating.

  As the electrolyte membrane 8, a known proton conductive solid polymer electrolyte membrane can be used. For example, a perfluorosulfonic acid-based fluorine ion exchange resin, more specifically, a hydrocarbon ion-exchange membrane C Examples include perfluorocarbon sulfonic acid polymers (PFS polymers) in which the —H bond is substituted with fluorine. 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 proton conductive polymer electrolytes include “Nafion” (registered trademark) manufactured by DuPont, “Flemion” (registered trademark) manufactured by Asahi Glass Co., Ltd., and “Aciplex” manufactured by Asahi Kasei Corporation. (Registered trademark), “Gore Select” (registered trademark) manufactured by Gore, and the like.

  A pair of mask films 5 is placed on each of the predetermined positions on both surfaces of the electrolyte membrane 8 as described above, and the catalyst layer 3 faces the mask film 5 at each predetermined position on each mask film 5. The layer forming film 1 is placed in an overlapping manner.

  The catalyst layer 3 can be in contact with the surface of the electrolyte membrane 8 through the opening 6 of the mask film 5, and only in contact with the mask film 5 at a portion other than the opening 6, and cannot be in contact with the electrolyte membrane 8.

  In this way, the mask film 5 is sandwiched between the electrolyte membrane 8 and each catalyst layer forming film 1 and is subjected to hot pressing, whereby only the opening 6 of the mask film 5 is provided on both surfaces of the electrolyte membrane 8. Joining with the catalyst layer 3 occurs. The hot pressing performed when manufacturing such a strip-shaped electrolyte membrane-catalyst layer assembly can be performed using a known technique such as a pressure roll or a flat plate press.

  Next, the base film 2 and the mask film 5 are peeled off from the joined body of the electrolyte membrane 8 and the catalyst layer forming film 1, whereby the catalyst layer 3 is formed on both surfaces of the electrolyte membrane 8, and the electrolyte membrane-catalyst layer. A joined body is obtained.

  Furthermore, an electrolyte membrane-electrode assembly in which a catalyst layer is formed on the electrolyte membrane is obtained by disposing electrode substrates on both surfaces of the obtained electrolyte membrane-catalyst layer assembly (see FIGS. 15 and 16). ). In addition, conventionally well-known carbon materials, such as carbon paper and a carbon cloth, can be used for an electrode base material, and it can be joined on the catalyst layer of an electrolyte membrane-catalyst layer assembly | attachment by hot press etc. FIG.

  By manufacturing the electrolyte membrane-electrode assembly as described above, the catalyst layer 3 depending on the shape of the opening 6 can be formed on the electrolyte membrane 8. Therefore, if a mask film 5 having openings of various shapes is prepared in advance, a catalyst layer having a desired shape can be easily formed on the electrolyte membrane 8.

  If the release layer 4 is formed on the base film 2, the transfer of the catalyst layer 3 from the catalyst layer forming film 1 ′ to the electrolyte membrane 8 can be facilitated.

  Further, if the release layer 7 is provided on the mask film 5, the transfer of the catalyst layer 3 to the mask film is prevented, so that the mask film 5 can be reused repeatedly, and a large amount of electrolyte can be obtained from one mask film 5. A membrane-catalyst layer assembly can be produced, which has the advantage of improving productivity.

  Note that the number of openings 6 provided in the mask film 5 is not limited to one, and there may be two or more openings 6 as shown in FIG. In that case, a plurality of catalyst layers 3 are formed on the electrolyte membrane 8, but a plurality of electrolyte membrane-catalyst layers are formed by cutting the joined body of the electrolyte membrane 8 and the catalyst layer forming film 1 into a desired shape. The joined body can be manufactured at the same time.

  Furthermore, as shown in FIG. 6, the shapes of the plurality of openings formed in the mask film are not necessarily the same, and an arbitrary number of openings having an arbitrary shape may be formed.

  In order to produce a homogeneous electrolyte membrane-catalyst layer assembly in large quantities at low cost and with high productivity, it is desirable to use a roll-shaped electrolyte membrane, a catalyst layer forming film, and a mask film.

  For example, in the system shown in FIGS. 7 to 9, the roll-shaped electrolyte film 8 is overlaid with the roll-shaped mask film 5, and the catalyst layer forming film 1 is further in contact with the mask film 5. By stacking and configuring these continuous conveyance lines, and further continuously performing hot pressing with the hot roll 10, an electrolyte membrane-catalyst layer assembly can be continuously produced in large quantities.

  In the system shown in FIGS. 7 to 9, the mask film 5 and the base film 2 after transfer are wound up from the joined body 11 of the electrolyte membrane 8 and the catalyst layer forming film 1 without peeling off. In this case, the base film 2 can be used as a film for protecting the catalyst layer 3. For example, the base film 2 is provided with a gas barrier property and the periphery thereof is heat-sealed, whereby the catalyst layer 3 is It can be protected from contamination and deterioration due to contact with.

  On the other hand, as shown in FIGS. 10 to 12, the base film 2 can be peeled off from the joined body of the electrolyte membrane 8 and the catalyst layer forming film 1, and in this case, the wound mask film 5 can be reused immediately.

  Furthermore, as shown in FIG. 13 and FIG. 14, it is also possible to manufacture the electrolyte membrane-catalyst layer assembly 11 while manufacturing the catalyst layer forming film 1 in-line. There is an advantage that a space for storing the film 1 is not required and a risk that the catalyst layer is contaminated or deteriorated during storage can be reduced. The catalyst layer forming film 1 is manufactured by a known method as described above.

  Further, in the system shown in FIG. 13, the transferred mask film 5 and base film 2 are wound from the joined body of the electrolyte membrane 8 and the catalyst layer forming film 1 without being peeled off, and shown in FIG. In the system, the transferred mask film 5 and base film 2 are peeled off and wound up. The merit and demerit of the difference in the winding method of the electrolyte membrane-catalyst layer assembly are as described above. Whether the mask film 5 and the base film 2 are peeled off before the winding or not is the electrolyte membrane- An advantageous method for handling the catalyst layer assembly and the mask film 5 may be selected. Thus, by constructing a system for producing an electrolyte membrane-catalyst layer assembly while producing the catalyst layer forming film 1 in-line, an electrolyte membrane-catalyst layer assembly is produced in large quantities continuously with high productivity. Is possible.

  In the said embodiment, although only the heat roll was illustrated as a heat press, a flat plate press can also be used by making an electrolyte membrane, a mask film, a base film, and the film for catalyst layer formation into intermittent feed.

  Subsequent to the production line for the electrolyte membrane-catalyst layer assembly, a line for joining the electrode base material can be provided. FIG. 15 shows a first embodiment of a line for joining an electrode substrate to an electrolyte membrane-catalyst layer assembly.

  The electrode base material joining line includes a line 13 for transporting the electrolyte membrane-catalyst layer assembly 11, a first placement station 15 for placing one electrode base material 14 on the catalyst layer 3, and a placed electrode. A first hot press 16 for joining the base material 14 to the catalyst layer 3; a reversing station 17 for twisting and reversing the line 13; a second placement station 19 for placing the other electrode base material 18 on the catalyst layer 3; And a second hot press 20 for joining the placed electrode substrate 18 to the catalyst layer 3. The electrolyte membrane-electrode assembly produced in this electrode base material joining line is cut out for each unit.

  FIG. 16 shows a second embodiment of the electrode base material joining line. In the second embodiment, an electrode base material transport line 22 for transporting the electrode base material 18 at a predetermined interval is provided below the line 21 for transporting the electrolyte membrane-catalyst layer assembly 11. Moreover, the mounting station 15 which mounts one electrode base material 14 on the catalyst layer 3, and the hot press 23 which joins the electrode base materials 14 and 18 to each of the catalyst layers 3 and 3 on both upper and lower sides are provided. ing. The electrolyte membrane-electrode assembly manufactured in the electrode substrate bonding line is cut out for each unit.

  The present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and the present invention has substantially the same configuration as the technical idea described in the claims of the present invention, and any device that exhibits the same function and effect is the present invention. It is included in the technical scope of the invention.

FIG. 1 is a schematic view schematically showing an example of a method for producing an electrolyte membrane-catalyst layer assembly according to the present invention. FIG. 2 is a cross-sectional view schematically showing an example of a film for forming a catalyst layer used for producing the electrolyte membrane-catalyst layer assembly of the present invention. FIG. 3 is a cross-sectional view schematically showing an example of a film for forming a catalyst layer used for producing the electrolyte membrane-catalyst layer assembly of the present invention. FIG. 4 is a cross-sectional view schematically showing an example of a mask film used for producing the electrolyte membrane-catalyst layer assembly of the present invention. FIG. 5 is a schematic view schematically showing an example of a method for producing an electrolyte membrane-catalyst layer assembly according to the present invention. FIG. 6 is a schematic view schematically showing an example of a method for producing an electrolyte membrane-catalyst layer assembly according to the present invention. FIG. 7 is a side view schematically showing an example of an apparatus for producing an electrolyte membrane-catalyst layer assembly according to the present invention. FIG. 8 is a perspective view schematically showing an apparatus for manufacturing the electrolyte membrane-catalyst layer assembly shown in FIG. FIG. 9 is a side view schematically showing the manufacturing apparatus for the electrolyte membrane-catalyst layer assembly shown in FIG. FIG. 10 is a side view schematically showing another example of the apparatus for producing an electrolyte membrane-catalyst layer assembly according to the present invention. FIG. 11 is a perspective view schematically showing an apparatus for manufacturing the electrolyte membrane-catalyst layer assembly shown in FIG. FIG. 12 is a side view schematically showing the manufacturing apparatus for the electrolyte membrane-catalyst layer assembly shown in FIG. FIG. 13: is a side view which shows an outline regarding the further another example of the manufacturing apparatus of the electrolyte membrane-catalyst layer assembly based on this invention. FIG. 14 is a side view schematically showing still another example of the apparatus for manufacturing an electrolyte membrane-catalyst layer assembly according to the present invention. It is a side view which shows roughly 1st Embodiment of the manufacturing line which joins an electrode base material to the electrolyte membrane-catalyst layer assembly which concerns on this invention. It is a side view which shows roughly 2nd Embodiment of the manufacturing line which joins an electrode base material to the electrolyte membrane-catalyst layer assembly which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,1 'Catalyst layer formation film 2 Base film 3 Catalyst layer 4 Release layer 5 Mask film 6 Opening part 7 Release layer 8 Electrolyte film 10 Hot roll 11 Electrolyte film-catalyst layer assembly

Claims (6)

Arranging a catalyst layer forming film in which a catalyst layer is formed on a base film via a mask film in which desired openings are formed on both surfaces of the proton conductive electrolyte membrane;
Bonding the electrolyte membrane and the catalyst layer of the catalyst layer forming film through the opening of the mask film by hot pressing;
Winding up the joined body of the electrolyte membrane and the catalyst layer forming film without peeling off the mask film and the substrate film;
A method for producing an electrolyte membrane-catalyst layer assembly for a polymer electrolyte fuel cell, comprising: The method for producing an electrolyte membrane-catalyst layer assembly according to claim 1, further comprising a step of heat-sealing the periphery of the base film after winding the assembly.   The method for producing an electrolyte membrane-catalyst layer assembly according to claim 1 or 2, wherein the mask film has a release layer on a surface in contact with the catalyst layer forming film.   The electrolyte according to any one of claims 1 to 3, wherein the proton conductive electrolyte membrane, the mask film, and the catalyst layer forming film are continuously supplied and hot pressing is continuously performed. A method for producing a membrane-catalyst layer assembly. An electrolyte membrane conveyance line for conveying the polymer solid electrolyte membrane;
A catalyst layer forming film transport line for transporting a catalyst layer forming film in which a catalyst layer is formed on a base film;
A mask film transport line for transporting a mask film having a desired opening formed between the electrolyte membrane and the catalyst layer forming film;
A hot press for joining the electrolyte membrane and the catalyst layer of the catalyst layer forming film through the opening of the mask film;
Have a, the mask film and the base film, characterized in that winding the assembly of the electrolyte membrane and the catalyst layer forming film without peeling off the solid polymer electrolyte fuel cell electrolyte membrane - A device for producing a catalyst layer assembly.   The manufacturing apparatus according to claim 5, wherein the hot press is a pressure roll or a flat plate press.

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