JP6120674B2 - Solid polymer fuel cell and manufacturing method thereof - Google Patents

Description

  The present invention relates to an electrolyte membrane-catalyst layer assembly with a reinforcing sheet, an electrolyte membrane-electrode assembly with a reinforcing sheet, and a solid polymer fuel cell using the same.

  A fuel cell is a cell in which electrodes are arranged on both sides of an electrolyte membrane and generates electricity by an electrochemical reaction between hydrogen and oxygen, and only water is generated during power generation. Thus, unlike the conventional internal combustion engine, it is expected to spread as a next-generation clean energy system because it does not generate environmental load gas such as carbon dioxide. In particular, the polymer electrolyte fuel cell has a low operating temperature and a low resistance of the electrolyte membrane. In addition, since it uses a highly active catalyst, it can obtain a high output even in a small size, as a home cogeneration system, etc. Early commercialization is expected.

  This polymer electrolyte fuel cell uses a solid polymer electrolyte membrane having proton conductivity, and a catalyst layer and a gas diffusion layer are sequentially laminated on both surfaces of the electrolyte membrane. And it has the structure which has arrange | positioned the gasket so that the circumference | surroundings of the electrode which consists of this catalyst layer and a gas diffusion layer may be enclosed, and also this was pinched | interposed with the separator (for example, refer FIG. 2 of patent document 1). Further, since the gasket is installed so as to surround the outer side of the electrode from the viewpoint of positional accuracy, a gap is formed between the gasket and the electrode, and the electrolyte membrane corresponding to this gap portion is an electrode. It is in a state where it is not pressed by either of the gaskets. Here, when power generation / non-power generation is repeated in the polymer electrolyte fuel cell, the electrolyte membrane repeats a wet state and a dry state, but the electrolyte membrane corresponding to the gap is pressed by an electrode or a gasket. Therefore, expansion and contraction are repeated. As a result, there is a problem that stress is generated in the electrolyte membrane and fatigues, and the electrolyte membrane is damaged.

  In order to solve this problem, for example, the polymer electrolyte fuel cell disclosed in Patent Document 1 further includes a reinforcing film in a gap between the electrode and the gasket. This reinforcing membrane is formed in a frame shape having an opening at the center portion, like the gasket, and its outer peripheral edge is sandwiched between the gasket and the electrolyte membrane, and its inner peripheral edge is separated from the separator. It is sandwiched between the gas diffusion layers. As described above, the polymer electrolyte fuel cell of Patent Document 1 restrains the expansion / contraction of the electrolyte membrane by restraining the gap between the gasket and the electrode by the reinforcing membrane.

Japanese Patent No. 3052536

  However, in the polymer electrolyte fuel cell using the reinforcing membrane, the inner peripheral edge of the reinforcing membrane is arranged on the gas diffusion layer, so that a step is formed on the gas diffusion layer by the thickness of the reinforcing membrane. End up. For this reason, the separator installed on the gas diffusion layer becomes non-uniform in contact with the gas diffusion layer, resulting in a problem that current collection efficiency from the gas diffusion layer is reduced.

Therefore, the present invention provides a polymer electrolyte fuel cell that does not cause a problem that current collection efficiency decreases due to uneven contact between the separator and the gas diffusion layer due to a step corresponding to the thickness of the reinforcing film on the gas diffusion layer. The issue is to provide.

A solid polymer fuel cell according to the present invention is made to solve the above-described problems, and includes a solid polymer electrolyte membrane, catalyst layers formed on both surfaces of the electrolyte membrane, the electrolyte membrane, A frame-shaped reinforcing sheet having an opening in the center, which is installed on both surfaces of an electrolyte membrane-catalyst layer assembly comprising a catalyst layer, and the catalyst layer is exposed from the opening except for the outer peripheral edge. The reinforcing sheet welded on the outer peripheral edge of the catalyst layer, and the thickness of the portion of the reinforcing sheet on the outer peripheral edge only in the opening of the reinforcing sheet. thick, said each catalyst layer gas diffusion layer formed on a gasket disposed respectively on each reinforcing sheet so as to surround the periphery of each electrode with the catalyst layer and the gas diffusion layer, wherein each of the electrodes and On gasket Comprising a separator disposed respectively, and each reinforcing sheet is composed of at least two layers.

Thus, a polymer electrolyte fuel cell is configured, the gas diffusion layer is formed in the opening of the reinforcing sheet, the reinforcing sheet is on the gas diffusion layer is not placed. Therefore, a flat surface without a step is formed on the gas diffusion layer, and the separator installed on the gas diffusion layer is in uniform contact with the gas diffusion layer, resulting in a problem that the current collection efficiency is lowered. There is no.

According to the present invention, there is provided a solid polymer fuel cell that does not cause a problem that current collection efficiency is reduced due to uneven contact between the separator and the gas diffusion layer due to a step corresponding to the thickness of the reinforcing film on the gas diffusion layer. Can be provided.

1 is a front sectional view showing an embodiment of a polymer electrolyte fuel cell according to the present invention. 1 is a plan view showing an embodiment of a polymer electrolyte fuel cell according to the present invention. It is an expanded front sectional view showing details of an outer periphery part of an electrolyte membrane-electrode assembly with a reinforcing sheet concerning this embodiment. It is explanatory drawing which shows the manufacturing method of the polymer electrolyte fuel cell which concerns on this embodiment. It is explanatory drawing which shows the manufacturing method of the electrolyte membrane-catalyst layer assembly | attachment with a reinforcement sheet which concerns on this embodiment.

  Hereinafter, embodiments of an electrolyte membrane-catalyst layer assembly with a reinforcing sheet, an electrolyte membrane-electrode assembly with a reinforcing sheet, and a polymer electrolyte fuel cell according to the present invention will be described with reference to the drawings. FIG. 1 is a front sectional view of a polymer electrolyte fuel cell according to this embodiment, FIG. 2 is a plan view of the polymer electrolyte fuel cell according to this embodiment, and FIG. 3 is an electrolyte membrane-electrode assembly with a reinforcing sheet. It is an expanded front sectional view which shows the detail of the outer periphery part. In FIG. 2, the description of the separator and the gasket is omitted for easy understanding.

  As shown in FIGS. 1 and 2, the polymer electrolyte fuel cell 1 includes an electrolyte membrane 2 having a rectangular shape in plan view, and a plan view that is slightly smaller than the electrolyte membrane 2 on the upper and lower surfaces of the electrolyte membrane 2. A rectangular catalyst layer 3 is formed. A structure in which the catalyst layer 3 is formed on both surfaces of the electrolyte membrane 2 is referred to as an electrolyte membrane-catalyst layer assembly 10. Thus, since the catalyst layer 3 is formed slightly smaller than the electrolyte membrane 2, the catalyst layer 3 is not formed on the outer peripheral edge 21 of the electrolyte membrane 2. In addition, it is preferable that the distance C (refer FIG. 3) from the outer periphery of the electrolyte membrane 2 to the outer periphery of the catalyst layer 3 is 0.1-5 mm.

  And the frame-shaped reinforcement sheet 4 which has the opening part 41 in the center is welded to the upper surface and lower surface of this electrolyte membrane-catalyst layer assembly 10, respectively. The reinforcing sheet 4 includes a gas barrier layer 42 that prevents permeation of fuel gas and oxidant gas used for power generation of the fuel cell, and a weld layer 43 that is welded to the electrolyte membrane-catalyst layer assembly 10. The layer 43 is directed to the electrolyte membrane-catalyst layer assembly 10 side. The thickness of the gas barrier layer 42 is preferably 5 to 50 μm, and the thickness of the welding layer 43 is preferably 1 to 50 μm. In a state where the reinforcing sheet 4 is welded to the electrolyte membrane-catalyst layer assembly 10, the catalyst layer 3 is exposed from the opening 41 of the reinforcing sheet 4 except for the outer peripheral edge portion 31, and the outside of the catalyst layer 3. The reinforcing sheet 4 is welded on the peripheral edge 31 and the outer peripheral edge 21 of the electrolyte membrane 2. In addition, it is preferable that the distance B (refer FIG. 3) from the outer periphery of the catalyst layer 3 to the inner periphery of the reinforcement sheet 4 shall be 1-10 mm. Further, since the reinforcing sheet 4 is formed to be slightly larger than the electrolyte membrane 2, the outer peripheral edge portions 45 of the reinforcing sheets 4 protruding from the electrolyte membrane 2 are welded to the outside of the electrolyte membrane 2. The distance D (see FIG. 3) from the outer peripheral edge of the reinforcing sheet 4 to the outer peripheral edge of the electrolyte membrane 2 is preferably 1 to 100 mm. As described above, the electrolyte membrane-catalyst layer assembly 10 having the reinforcing sheet 4 welded thereto corresponds to the electrolyte membrane-catalyst layer assembly with a reinforcing sheet of the present invention.

  A gas diffusion layer 5 having a rectangular shape in plan view is formed on the catalyst layer 3 exposed from the opening 41 of the reinforcing sheet 4. The distance A (see FIG. 3) from the outer peripheral edge of the gas diffusion layer 5 to the inner peripheral edge of the reinforcing sheet 4 is preferably 0 to 5 mm. Thus, the gas diffusion layer 5 is formed on the catalyst layer 3 to constitute the electrode E, and the electrode E formed on both surfaces of the electrolyte membrane 2 is called an electrolyte membrane-electrode assembly 20. In addition, like this embodiment, what the reinforcing sheet 4 is installed in the electrolyte membrane-electrode assembly 20 corresponds to the electrolyte membrane-electrode assembly with a reinforcing sheet of the present invention.

  A frame-shaped gasket 6 is installed so as to surround the periphery of the electrode E, and a separator 7 is installed on the electrode E and the gasket 6. In the separator 7, a gas flow path 71 is formed in a region facing the gas diffusion layer 5.

  Next, the material of each component of the polymer electrolyte fuel cell 1 configured as described above will be described.

  The electrolyte membrane 2 is formed, for example, by applying a solution containing a hydrogen ion conductive polymer electrolyte on a substrate and drying it. Examples of the hydrogen ion conductive polymer electrolyte membrane include perfluorosulfonic acid-based fluorine ion exchange resins, more specifically, perfluorocarbon sulfonic acid in which the C—H bond of the hydrocarbon-based ion exchange membrane is substituted with fluorine. -Based polymer (PFS-based polymer) and the like. 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 hydrogen ion conductive polymer electrolyte 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. The concentration of the hydrogen ion conductive polymer electrolyte contained in the hydrogen ion conductive polymer electrolyte-containing solution is usually about 5 to 60% by weight, preferably about 20 to 40% by weight. In addition, the film thickness of the electrolyte membrane 2 is about 20-250 micrometers normally, Preferably it is about 20-80 micrometers. In addition to the hydrogen ion conductive polymer electrolyte membrane, an anion conductive solid polymer electrolyte membrane and a liquid substance-impregnated membrane are also included. Examples of the anion conductive electrolyte membrane include a hydrocarbon resin or a fluorine resin, and specific examples of the hydrocarbon resin include Aciplex (registered trademark) A201, 2111, 221 manufactured by Asahi Kasei Corporation, and Tokuyama. Neocepta (registered trademark) AM-1, AHA, etc. manufactured by Co., Ltd. may be mentioned, and examples of the fluorine-based resin may include Tosflex (registered trademark) IE-SF34 manufactured by Tosoh Corporation. Examples of the liquid substance-impregnated film include polybenzimidazole (PBI).

  The catalyst layer 3 is a known platinum-containing catalyst layer (cathode catalyst and anode catalyst). Specifically, the catalyst layer 3 contains carbon particles supporting catalyst 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 and the like. In general, the catalyst particles contained in the cathode catalyst layer are platinum, and the catalyst particles contained in the anode catalyst layer are an alloy of the metal and platinum. Moreover, as a hydrogen ion conductive polymer electrolyte, the same material as what is used for the electrolyte membrane 2 mentioned above can be used.

  The reinforcing sheet 4 includes a gas barrier layer 42 and a welded layer 43. The gas barrier layer 42 is made of polyester, polyamide, polyimide, polymethyl pentene, polyphenylene having barrier properties against water vapor, water, fuel gas, and oxidant gas. Oxide, polysulfone, polyether ether ketone, polyphenylene sulfide, and the like can be preferably used. Specific examples of the polyester include polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, and polybutylene naphthalate.

  The material of the weld layer 43 is preferably a polyolefin resin, for example, medium density polyethylene, high density polyethylene, linear low density polyethylene, ethylene-α-olefin copolymer, polypropylene, polybutene, polyisobutene, poisobutylene, Copolymer of ethylene and unsaturated carboxylic acid such as polybutadiene, polyisoprene, ethylene-methacrylic acid copolymer, or ethylene-acrylic acid copolymer, ethylene-ethyl acrylate copolymer, ionomer resin, ethylene-acetic acid Vinyl copolymers and the like can be used. In addition, acid-modified polyolefin resins and silane-modified polyolefin resins modified with them can be used. Among them, it is insulating to use polypropylene modified with unsaturated carboxylic acid or polyethylene modified with unsaturated carboxylic acid. Or it is preferable in terms of heat resistance.

  As the gas diffusion layer 5, various types of gas diffusion layers constituting a fuel electrode and an air electrode can be used. In order to efficiently supply fuel gas and oxidant gas as fuel to the catalyst layer 3, the gas diffusion layer 5 is porous. It is made of a conductive substrate. Examples of the porous conductive substrate include carbon paper and carbon cloth.

  As the gasket 6, it is possible to use a gasket that has a strength sufficient to withstand heat pressing and has a gas barrier property that does not leak fuel and oxidant to the outside. For example, a polyethylene terephthalate sheet or Teflon ( (Registered trademark) sheet, silicon rubber sheet, and the like.

  The separator 7 may be any known conductive plate that is known and stable even in the environment within the fuel cell. In general, a carbon plate in which a gas flow path 71 is formed is used. In addition, the separator 7 is made of a metal such as stainless steel, and the surface of the metal is formed with a coating made of a conductive material such as chromium, a platinum group metal or oxide thereof, or a conductive polymer. It is also possible to use a metal having a metal surface plated with a material such as silver, a platinum group composite oxide, or chromium nitride.

  Next, a method for producing the above-described polymer electrolyte fuel cell 1 will be described with reference to the drawings. FIG. 4 is an explanatory view showing a method for producing the polymer electrolyte fuel cell 1 according to this embodiment.

  As shown in FIG. 4, an electrolyte membrane 2 made of the above-described material is prepared, and a catalyst layer forming transfer sheet 8 is placed on both surfaces of the electrolyte membrane 2 in an overlapping manner. Here, the transfer sheet 8 for forming a catalyst layer is one in which the transferred catalyst layer 3 is formed on a transfer substrate 81. The production method of the catalyst layer forming transfer sheet 8 will be described. First, the above-described carbon particles supporting the catalyst particles and the hydrogen ion conductive polymer electrolyte are mixed and dispersed in an appropriate solvent to prepare a catalyst paste. . Then, the catalyst paste is applied onto the transfer substrate 81 through a release layer as necessary in accordance with a known method so that the formed catalyst layer 3 has a desired film thickness. At this time, the catalyst paste is applied to the transfer substrate 81 so that the catalyst layer 3 has a shape slightly smaller than the electrolyte membrane 2. Examples of the method for applying the catalyst paste include known coating methods such as screen printing, spray coating, die coating, and knife coating. Examples of the solvent include various alcohols, various ethers, various dialkyl sulfoxides, water, or a mixture thereof. Of these, alcohols are preferable. Examples of alcohols include monohydric alcohols having 1 to 4 carbon atoms such as methanol, ethanol, n-propanol, isopropanol, n-butanol, and tert-butanol, and various polyhydric alcohols. Examples of the transfer base 81 include polyimide, polyethylene terephthalate, polyparvanic acid aramid, polyamide (nylon), polysulfone, polyethersulfone, polyphenylene sulfide, polyetheretherketone, polyetherimide, polyarylate, polyethylene naphthalate, and the like. Can be mentioned. Further, heat resistance of ethylene tetrafluoroethylene copolymer (ETFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), tetrafluoroperfluoroalkyl vinyl ether copolymer (PFA), polytetrafluoroethylene (PTFE), etc. Fluorine resin can also be used. Further, the transfer substrate 81 may be coated paper such as art paper, coated paper, lightweight coated paper, non-coated paper such as notebook paper, copy paper, etc. in addition to the polymer film. The thickness of the transfer substrate 81 is usually about 6 to 100 μm, preferably about 10 to 30 μm, from the viewpoints of handleability and economy. Therefore, the transfer substrate 81 is preferably a polymer film that is inexpensive and easily available, and more preferably polyethylene terephthalate.

  Then, after applying the catalyst paste, the catalyst layer 3 is formed on the transfer substrate 81 by drying at a predetermined temperature and time. A drying temperature is about 40-100 degreeC normally, Preferably it is about 60-80 degreeC. Although depending on the drying temperature, the drying time is usually about 5 minutes to 2 hours, preferably about 10 minutes to 1 hour.

  Returning to FIG. 4, the description of the method for producing the polymer electrolyte fuel cell will be continued. The transfer sheet 8 for forming a catalyst layer produced as described above is disposed so that the catalyst layer 3 faces the electrolyte membrane 1 (FIG. 4A), and a heat press is applied from the back side of the transfer sheet 8 to apply the catalyst layer. 3 is transferred to the electrolyte membrane 2, and the transfer substrate 81 of the transfer sheet 8 is peeled off (FIG. 4B). In consideration of workability, it is preferable to simultaneously laminate the catalyst layer 3 on both surfaces of the electrolyte membrane 2, but the catalyst layer 3 can also be formed on each side. The pressure level of the heating press is usually about 0.5 to 20 MPa, preferably about 1 to 10 MPa in order to avoid transfer failure. Further, it is preferable to heat the pressing surface during this pressing operation in order to avoid transfer failure. The heating temperature is usually 200 ° C. or lower, preferably 150 ° C. or lower, in order to avoid damage or deformation of the electrolyte membrane 2. Thus, the electrolyte membrane-catalyst layer assembly 10 is formed by forming the catalyst layers 3 on both surfaces of the electrolyte membrane 2. At this time, since the catalyst layer 3 is slightly smaller than the electrolyte membrane 2, the outer peripheral edge 21 of the electrolyte membrane 2 is exposed.

  Next, the reinforcing sheet 4 is attached to the electrolyte membrane-catalyst layer assembly 10 thus formed (FIG. 4C). This process will be described in detail with reference to FIG. FIG. 5 is a plan view showing a process of attaching the reinforcing sheet 4 to the electrolyte membrane-catalyst layer assembly 10. As shown in FIG. 5, the two reinforcing sheets 4 made of the above-described materials are overlapped, and the remaining three sides are left welded together. As a result, the two reinforcing sheets 4 are formed into a bag body in which a welded portion is formed in a U-shape and the left side is open (FIG. 5A). As this welding method, various known methods can be adopted. For example, high-frequency welding, hot air welding, hot plate welding, impulse welding, trowel welding, ultrasonic welding, etc. can be adopted. .

  When the bag body is formed by the reinforcing sheet 4, next, an easily removable region 44 that is slightly smaller than the catalyst layer 3 of the electrolyte membrane-catalyst layer assembly 10 is formed at the center of each reinforcing sheet 4 constituting the bag body. (FIG. 5B). The easy removal region 44 refers to a region that can be easily removed. For example, the easy removal region 44 can be formed by making a perforation in the outer peripheral edge or making a cut while leaving only a part. The electrolyte membrane-catalyst layer assembly 10 is inserted into the bag body in which the easy-removal region 44 is formed in this manner from the unwelded left side and moved to a predetermined position (FIG. 5C). The predetermined position refers to a position where the catalyst layer 3 of the electrolyte membrane-catalyst layer assembly 10 faces the easy removal region 44 except for the outer peripheral edge 31.

  After the electrolyte membrane-catalyst layer assembly 10 is moved to a predetermined position, the perforation at the outer peripheral edge of the easy-removal region 44 is cut and the easy-removal region 44 is removed from each reinforcing sheet 4, thereby An opening 41 is formed at the center (FIG. 5D). When the easy removal regions 44 are thus removed from the reinforcing sheets 4 to form the openings 41, the catalyst layer 3 of the electrolyte membrane-catalyst layer assembly 10 is removed from the openings 41 except for the outer peripheral edge 31. It will be exposed. And the reinforcement sheet 4 is welded by a well-known method in the state which the reinforcement sheet 4 was not welded in this state, and the reinforcement sheet 4 is the outer peripheral edge part 31 of the catalyst layer 3 of the electrolyte membrane-catalyst layer assembly 10 or While being welded to the outer peripheral edge 21 of the electrolyte membrane 2, the reinforcing sheets 4 are also welded together. Through the above steps, the electrolyte membrane-catalyst layer assembly with a reinforcing sheet is completed (FIGS. 5E and 4C).

  Returning to FIG. 4, the description of the method for producing the polymer electrolyte fuel cell 1 will be continued. On the catalyst layer 3 exposed from the opening 41 of the electrolyte membrane-catalyst layer assembly with reinforcing sheet described above, the gas diffusion layer 5 is laminated by thermocompression bonding, so that the electrolyte membrane-electrode assembly with reinforcing sheet is formed. Completed (FIG. 4D). And the gasket 6 is arrange | positioned on the reinforcement sheet 4 so that the circumference | surroundings of the electrode E which consists of the catalyst layer 3 and the gas diffusion layer 5 may be enclosed. The separator 7 is disposed on the gas diffusion layer 5 and the gasket 6 so that the gas flow path 71 faces the gas diffusion layer 5 so that the gas diffusion layer 5 and the separator 7 are electrically connected. By sandwiching the electrolyte membrane-electrode assembly with the separator 7, the solid polymer fuel cell 1 is completed (FIG. 4E).

  As described above, in the present embodiment, the outer peripheral edge 21 of the electrolyte membrane 2 is restrained by the welded reinforcing sheet 4, so that the expansion / contraction of the electrolyte membrane 2 can be suppressed. Breakage of the electrolyte membrane 2 can be prevented. The reinforcing sheet 4 is welded on the outer peripheral edge 21 of the electrolyte membrane 2 and the outer peripheral edge 31 of the catalyst layer 3, but is not placed on the gas diffusion layer 5. For this reason, a flat surface is formed on the gas diffusion layer 5, and the separator 7 installed on the gas diffusion layer 5 is in uniform contact with the gas diffusion layer 5. Therefore, the problem that the current collection efficiency of the separator 7 is reduced does not occur.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to these, A various change is possible unless it deviates from the meaning of this invention. For example, in the above-described embodiment, the manufacturing method in which the reinforcing sheet 4 is once made into a bag and the electrolyte membrane-catalyst layer assembly 10 is inserted is adopted, but the present invention is not particularly limited thereto. For example, the reinforcing sheets 4 in which the opening portions 41 are formed in advance on both surfaces of the electrolyte membrane-catalyst layer assembly 10 are arranged so that the welding layer 43 faces the electrolyte membrane-catalyst layer assembly 10, respectively. The reinforcing sheet 4 can be welded to both surfaces of the electrolyte membrane-catalyst layer assembly 10 by a method or the like to produce an electrolyte membrane-catalyst layer assembly with a reinforcing sheet.

  Moreover, in the said embodiment, although the reinforcement sheet 4 is comprised from two layers, the gas barrier layer 42 and the welding layer 43, three or more layers may be sufficient.

In the above embodiment, the electrolyte membrane 2, the catalyst layer 3, and the gas diffusion layer 5 constituting the solid polymer fuel cell 1 are all described as a rectangular shape in plan view, but the shape is not particularly limited, For example, it can be a circular shape in plan view. An electrolyte membrane-catalyst layer assembly with a reinforcing sheet according to the present invention includes a solid polymer electrolyte membrane, a catalyst layer formed on each surface except for an outer peripheral edge of the electrolyte membrane, and the electrolyte membrane and the catalyst layer. A frame-shaped reinforcing sheet having an opening in the center, which is respectively installed on both surfaces of the electrolyte membrane-catalyst layer assembly, and each reinforcing sheet has an outer peripheral edge from the opening. It is welded on the outer peripheral edge of the catalyst layer and the outer peripheral edge of the electrolyte membrane so as to be exposed, and each reinforcing sheet is composed of at least two layers. The electrolyte membrane-catalyst layer assembly with a reinforcing sheet thus configured is usually used as a polymer electrolyte fuel cell. In this case, the electrode which consists of a catalyst layer and a gas diffusion layer is comprised by forming a gas diffusion layer on the catalyst layer exposed from the opening part of the reinforcement sheet. And a gasket is arrange | positioned on a reinforcement sheet so that the circumference | surroundings of an electrode may be enclosed. In this polymer electrolyte fuel cell, first, since the reinforcing sheet is welded on the outer peripheral edge of the electrolyte membrane where the catalyst layer is not formed, the gap between the gasket and the catalyst layer is formed by the reinforcing sheet. The electrolyte membrane corresponding to can be restrained. As a result, the expansion / contraction of the electrolyte membrane can be suppressed, and the electrolyte membrane can be prevented from being damaged. Further, the reinforcing sheet is welded not on the gas diffusion layer but on the outer peripheral edge of the catalyst layer. For this reason, the upper surface of the gas diffusion layer forms a flat surface without a step, and the separator installed on the gas diffusion layer has a problem in that the current collection efficiency is lowered due to uniform contact with the gas diffusion layer. It does not occur. The reinforcing sheet has a frame shape, and the “frame shape” is a concept including a rectangular frame in plan view, a circular frame in plan view, and the like. The electrolyte membrane-catalyst layer assembly with the reinforcing sheet can take various configurations. For example, the reinforcing sheet includes a welded layer welded to the electrolyte membrane-catalyst layer assembly, and a fuel gas and an oxidant gas. And a gas barrier layer that prevents permeation, and the weld layer is preferably arranged so as to face the electrolyte membrane-catalyst layer assembly side. Thus, the gas leakage to the outside can be more reliably prevented by providing the reinforcing sheet with a two-layer structure of the gas barrier layer and the welding layer. In addition, it is preferable that the said reinforcement sheet is formed one size larger than an electrolyte membrane, and the outer periphery edge parts located outside the electrolyte membrane are welded. Conventionally, in order to install the gasket, an electrolyte membrane that is somewhat larger than the electrode is used, and the gasket is installed on the outer peripheral edge of the electrolyte membrane where no electrode is formed. On the other hand, a gasket can be installed in this reinforcing sheet by using a reinforcing sheet that is slightly larger than the electrolyte membrane. As a result, the electrolyte membrane in which an expensive material is used can be reduced, and the cost can be reduced. The electrolyte membrane-electrode assembly with a reinforcing sheet according to the present invention is any one of the above electrolyte membrane-catalyst layer assembly with a reinforcing sheet and the opening of the reinforcing sheet, and is more than the thickness of the reinforcing sheet. And a gas diffusion layer formed on each catalyst layer thickly. In the electrolyte membrane-electrode assembly with the reinforcing sheet configured as described above, the reinforcing sheet is first disposed on the outer peripheral edge of the electrolyte membrane where the catalyst layer is not formed. The peripheral edge is constrained, expansion / contraction is suppressed, and as a result, damage to the electrolyte membrane caused by repeated expansion / contraction can be prevented. The gas diffusion layer is formed in the opening of the reinforcing sheet, and no reinforcing sheet is placed on the gas diffusion layer. Therefore, the gas diffusion layer has a flat surface without a step, and when the separator is installed on the gas diffusion layer, the gas diffusion layer and the separator are in uniform contact with each other, and the current collection efficiency decreases. Will not occur. Further, the polymer electrolyte fuel cell according to the present invention is provided on each of the reinforcing sheets so as to surround the electrolyte membrane-electrode assembly with the reinforcing sheet, and the respective electrodes including the catalyst layer and the gas diffusion layer. And a separator installed on each of the electrodes and the gasket. Thus, in the thus configured polymer electrolyte fuel cell, first, the reinforcing sheet is disposed on the outer peripheral edge of the electrolyte membrane in which the catalyst layer is not formed. Therefore, the outer peripheral edge of the electrolyte membrane is formed by the reinforcing sheet. Is restrained, expansion and contraction are suppressed, and damage to the electrolyte membrane caused by repeated expansion and contraction can be prevented. The gas diffusion layer is formed in the opening of the reinforcing sheet, and no reinforcing sheet is placed on the gas diffusion layer. Therefore, a flat surface without a step is formed on the gas diffusion layer, and the separator installed on the gas diffusion layer is in uniform contact with the gas diffusion layer, resulting in a problem that the current collection efficiency is lowered. There is no.

  The present invention will be described more specifically with reference to the following examples and comparative examples. In addition, this invention is not limited to the following Example.

Example 1
As the electrolyte membrane 2, NRE212CS (manufactured by Dupont) having a film thickness of 53 μm cut to a size of 63 × 63 mm was used.

Next, a transfer sheet 8 for forming a catalyst layer was produced in the following manner. First, 2 g of platinum catalyst-supported carbon (platinum support amount: 45.7 wt%, manufactured by Tanaka Kikinzoku Co., Ltd., TEC10E50E), 1-butanol 10 g, 3-butanol 10 g, fluororesin (5 wt% Nafion binder, manufactured by DuPont) 20 g and 6 g of water was added, and these were stirred and mixed with a disperser to prepare an ink composition for forming a catalyst. Next, the ink was coated on a polyester film (Toray, X44, film thickness 25 μm) so that the weight of platinum after drying the catalyst layer was 0.4 mg / cm ² to prepare a transfer sheet 8 for forming a catalyst layer. did.

  The catalyst layer-forming transfer sheet 8 produced as described above was cut into a size of 60 × 60 mm, and placed on both sides of the electrolyte membrane 2 so that the catalyst layer 3 faced the electrolyte membrane 2 side. The catalyst layer 3 was formed on both surfaces of the electrolyte membrane 2 by hot pressing under conditions of 135 ° C., 5.0 MPa, 150 seconds, and the electrolyte membrane-catalyst layer assembly 10 was produced. The catalyst layer 3 has a thickness of 20 μm.

  Subsequently, a reinforcing sheet 4 was produced. As the gas barrier layer 42 of the reinforcing sheet 4, biaxially stretched polyethylene naphthalate (manufactured by Teijin Limited, Teonex, film thickness: 12 μm) was used. On this polyethylene naphthalate, an unsaturated carboxylic acid graft-modified polypropylene was extruded at a thickness of 30 μm by a melt extrusion method to form a weld layer 43. The reinforcing sheet 4 was cut to a size of 80 × 80 mm, and an opening 41 having a size of 50 × 50 mm was formed at the center. And the reinforcement sheet 4 is arrange | positioned centering on both surfaces of the electrolyte membrane-catalyst layer assembly | attachment 10, and the reinforcement sheet 4 is electrolyte-membrane-catalyst layer by heat-pressing on conditions of 130 degreeC, 1.0 Mpa, and 30 second. It welded to the conjugate | zygote 10 and the electrolyte membrane-catalyst layer conjugate | bonded_body with a reinforcement sheet was produced.

  Subsequently, on the catalyst layer 3 exposed from the opening 41, a carbon paper (TGP-H-090, manufactured by Toray Industries, Inc., thickness 280 μm) cut into a size of 49 × 49 mm as the gas diffusion layer 5 is used. ) To form an electrolyte membrane-electrode assembly with a reinforcing sheet.

(Example 2)
In the polymer electrolyte fuel cell of Example 2, the material of the reinforcing sheet 4 is different, the conditions of the hot press in producing the electrolyte membrane-catalyst layer assembly 10 are different, and the reinforcing sheet 4 is used as the electrolyte membrane. An electrolyte membrane-electrode assembly with a reinforcing sheet was produced using the same materials, dimensions, and manufacturing method as in Example 1 except that the conditions of hot pressing at the time of welding to the catalyst layer assembly 10 were different.

  The material of the reinforcing sheet 4 was a biaxially stretched polyethylene terephthalate (manufactured by Teijin Ltd., Teflex, film thickness 20 μm) as the gas barrier layer 42. On this polyethylene terephthalate, an unsaturated carboxylic acid graft-modified polyethylene was extruded at a thickness of 30 μm by melt extrusion to form a weld layer 43.

  Further, the hot press conditions for producing the electrolyte membrane-catalyst layer assembly 10 are 130 ° C., 3.0 MPa, 120 seconds, and the hot press for welding the reinforcing sheet 4 to the electrolyte membrane-catalyst layer assembly 10. The conditions were 110 ° C., 1.0 MPa, and 10 seconds.

(Example 3)
As described above, except that the conditions of the hot press at the time of producing the electrolyte membrane-catalyst layer assembly 10 are different and the conditions of the hot press at the time of welding the reinforcing sheet to the electrolyte membrane-catalyst layer assembly 10 are different. An electrolyte membrane-electrode assembly with a reinforcing sheet was produced using the same materials, dimensions, and production method as in Example 1. In addition, the conditions of the hot press at the time of producing the electrolyte membrane-catalyst layer assembly 10 are 130 ° C., 3.0 MPa, 120 seconds, and the hot press at the time of welding the reinforcing sheet 4 to the electrolyte membrane-catalyst layer assembly 10. The conditions were 120 ° C., 1.0 MPa, and 10 seconds.

Example 4
An electrolyte membrane-electrode assembly with a reinforcing sheet was produced using the same material, dimensions, and manufacturing method as in Example 1 except that the transfer sheet 8 for forming a catalyst layer was cut to a size of 54 × 54 mm.

(Comparative Example 1)
An electrolyte membrane-electrode assembly was produced using the same material, dimensions, and manufacturing method as in Example 1 except that the reinforcing sheet 4 was not installed.

(Comparative Example 2)
The point that the transfer sheet 8 for forming the catalyst layer is cut to a size of 50 × 50 mm, that is, the reinforcing sheet 4 is not placed on the outer peripheral edge 31 of the catalyst layer 3 but on the outer peripheral edge 21 of the electrolyte membrane 2. An electrolyte membrane-electrode assembly with a reinforcing sheet was produced using the same material, dimensions, and production method as in Example 1 except that only the surface was mounted.

(Evaluation method)
For the electrolyte membrane-electrode assembly with reinforcing sheet of Examples 1 to 4, the electrolyte membrane-electrode assembly of Comparative Example 1, and the electrolyte membrane-electrode assembly with reinforcing sheet of Comparative Example 2, a gasket 6 and a separator 7 were installed. Each polymer electrolyte fuel cell was fabricated and subjected to a load fluctuation cycle test. The results are shown in Table 1. In Comparative Example 1, the gasket 6 was installed on the outer peripheral edge 21 of the electrolyte membrane 2. The measurement conditions at this time were a cell temperature of 80 ° C., a fuel utilization rate of 70%, an oxidant utilization rate of 40%, and a humidification temperature of 50 ° C. In the load fluctuation cycle test, a cycle in which power was generated at a current density of 0.3 A / cm ^{2 for} 1 minute and then generated at a current density of 0.01 A / cm ^{2 for} 1 minute was repeated. As a result of this load fluctuation cycle test, the voltage of the fuel cell of Example 1 drops after 1600 hours, the fuel cell of Example 2 reaches 2000 hours, and the fuel cell of Examples 3 and 4 drops even after 1000 hours. In addition, when the electrolyte membrane was confirmed after this load fluctuation cycle test, the electrolyte membrane was not damaged. On the other hand, a drop in voltage was confirmed at 300 hours for the fuel cell of Comparative Example 1 and 200 hours for the fuel cell of Comparative Example 2, and after performing this load fluctuation cycle test, Comparative Examples 1 and 2 were Damage to the electrolyte membrane 2 was confirmed visually. Furthermore, as a result of measuring the amount of leakage current after the load fluctuation cycle test, the amount of leakage current of the fuel cells of Examples 1 to 4 was 1 mA / cm ² or less, whereas the fuel cells of Comparative Examples 1 and 2 The amount of leakage current of the cell was 20 mA / cm ² or more, and gas leakage due to breakage of the electrolyte membrane was observed.

  As described above, in the polymer electrolyte fuel cell of Example 1, since the durability time is increased, the problem of the electrolyte membrane breakage was solved by using the polymer electrolyte fuel cell of the present invention. Recognize.

1 a solid polymer fuel cell 2 electrolyte membrane 21 electrolyte peripheral edge portion 3 catalyst layer 31 the outer peripheral edge 5 Gas diffusion of the outer peripheral edge portion 4 reinforcement sheet 41 opening 42 gas barrier layer 43 deposited layers 45 reinforcing sheet of the catalyst layer of the membrane Layer 6 Gasket 7 Separator 10 Electrolyte membrane-catalyst layer assembly 20 Electrolyte membrane-electrode assembly

Claims (6)

A solid polymer electrolyte membrane;
Catalyst layers respectively formed on both surfaces of the electrolyte membrane;
A frame-shaped reinforcing sheet having an opening in the center, installed on both surfaces of the electrolyte membrane-catalyst layer assembly comprising the electrolyte membrane and the catalyst layer, wherein the catalyst layer extends from the opening to the outer peripheral edge. A reinforcing sheet welded on the outer peripheral edge of the catalyst layer so as to be exposed ,
Said be only the opening of the reinforcing sheet, larger than the thickness of the portion on the outer periphery of the catalyst layer of the reinforcing sheet, a gas diffusion layer formed on the catalyst layers,
Gaskets respectively installed on the respective reinforcing sheets so as to surround each electrode having the catalyst layer and the gas diffusion layer;
A separator installed on each of the electrodes and the gasket, and
Wherein the reinforcing sheet is composed of at least two layers, a polymer electrolyte fuel cell.   The reinforcing sheet includes a weld layer welded to the electrolyte membrane-catalyst layer assembly and a gas barrier layer that prevents permeation of fuel gas and oxidant gas, and the weld layer is joined to the electrolyte membrane-catalyst layer. The polymer electrolyte fuel cell according to claim 1, which is disposed so as to face the body side.   The polymer electrolyte fuel cell according to claim 1, wherein the gas diffusion layer includes carbon paper or carbon cloth. A step of preparing a solid polymer electrolyte membrane;
Forming a catalyst layer on both surfaces of the electrolyte membrane;
A frame-shaped reinforcing sheet having an opening in the center on both surfaces of an electrolyte membrane-catalyst layer assembly comprising the electrolyte membrane and a catalyst layer, wherein the catalyst layer is exposed from the opening except for an outer peripheral edge portion. Installing a reinforcing sheet so as to be welded onto the outer peripheral edge of the catalyst layer ;
Forming a gas diffusion layer on each catalyst layer , which is thicker than the thickness of the portion on the outer peripheral edge of the catalyst layer of the reinforcement sheet only in the opening of the reinforcement sheet;
Providing a gasket on each reinforcing sheet so as to surround each electrode having the catalyst layer and the gas diffusion layer, and
Each of the reinforcing sheets is a method for producing a polymer electrolyte fuel cell , comprising at least two layers.   The method for producing a polymer electrolyte fuel cell according to claim 4, wherein the gas diffusion layer is formed by thermocompression bonding. 6. The method for producing a polymer electrolyte fuel cell according to claim 4, wherein the gas diffusion layer includes carbon paper or carbon cloth.

Images