JP5338998B2 - Electrolyte membrane-electrode assembly and solid polymer fuel cell using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrolyte membrane-electrode assembly with a reinforcing sheet, which can maintain a sufficient gas barrier property and can prevent a damage of the electrolyte membrane, and to provide a solid polymer fuel cell using the assembly. <P>SOLUTION: The electrolyte membrane-electrode assembly includes a solid polymer electrolyte membrane 2, catalyst layers 3 formed on each of both sides of the electrolyte membrane 2 excluding its circumferential portion 21, a gas diffusion layer 4 formed on each of the catalyst layers 3, and reinforcing sheets 5 which are arranged on each of both surfaces of the electrolyte membrane electrode assembly 20 composed of the electrolyte membrane 2, the catalyst layers 3 and the gas diffusion layers 4 and which respectively include a gas barrier layer 52 for preventing a permeation of a fuel gas and an oxidant gas and a welding layer 53 which can be welded with the electrolyte membrane-electrode assembly 20. Each of the reinforcing sheets 5 is in a shape of a frame having an open portion 51 in a center and is arranged to cover an outer circumferential portion 41 of the gas diffusion layer 4 and an outer circumferential portion 21 of the electrolyte membrane 2 so that the gas diffusion layer 4 can be exposed out of the open portion 51 except its outer circumferential portion 41. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention relates to an electrolyte membrane-electrode assembly and a polymer electrolyte fuel cell using the same.

  A fuel cell is a cell in which electrodes are arranged on both sides of an electrolyte 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 low electrolyte resistance. In addition, it uses a highly active catalyst, so it can obtain high output even in a small size. Is expected to be put to practical use.

  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, since the reinforcing membrane of the polymer electrolyte fuel cell is composed of a single layer made of polyolefin resin such as polypropylene resin or polyethylene resin, there is a problem that gas barrier properties are not sufficient.

  Accordingly, the present invention provides an electrolyte membrane-electrode assembly with a reinforcing sheet and a solid polymer fuel cell using the same, which can prevent damage to the electrolyte membrane while having sufficient gas barrier properties. Is an issue.

  The electrolyte membrane-electrode assembly with a reinforcing sheet according to the present invention is made to solve the above-described problems, and is formed on both sides of the solid polymer electrolyte membrane and the outer peripheral edge of the electrolyte membrane. A catalyst layer, a gas diffusion layer formed on each of the catalyst layers, and an electrolyte membrane-electrode assembly comprising the electrolyte membrane, the catalyst layer, and the gas diffusion layer, respectively. A reinforcing sheet having a gas barrier layer for preventing gas permeation and a welding layer to be welded to the electrolyte membrane-electrode assembly, each reinforcing sheet having a frame shape having an opening in the center. The gas diffusion layer is welded onto the outer peripheral edge of the gas diffusion layer and the outer peripheral edge of the electrolyte membrane so that the gas diffusion layer is exposed from the opening except for the outer peripheral edge.

  The electrolyte membrane-catalyst layer assembly with a reinforcing sheet thus configured is usually used as a polymer electrolyte fuel cell. In this case, a polymer electrolyte fuel cell is configured by arranging a gasket on the reinforcing sheet so as to surround the periphery of the electrode composed of the catalyst layer and the gas diffusion layer, and arranging the separator on the electrode and the gasket. . In this polymer electrolyte fuel cell, a reinforcing sheet is welded to the outer peripheral edge of an electrolyte membrane in which a catalyst layer is not formed. For this reason, the electrolyte membrane corresponding to the gap portion between the catalyst layer and the gasket is restrained by the reinforcing sheet. Therefore, the electrolyte membrane can be prevented from being damaged by suppressing expansion and contraction. In addition, in order to generate power in this polymer electrolyte fuel cell, fuel gas is supplied from the gas flow path of one separator and oxidant gas is supplied from the gas flow path of the other separator. Since the reinforcing sheet partially welded to the part has a gas barrier layer on the upper surface thereof, that is, the separator side to which fuel gas or oxidant gas is supplied, the fuel gas and oxidant gas are reinforced. It is possible to solve the problem of leaking outside through the.

  The electrolyte membrane-electrode assembly with a reinforcing sheet can have various configurations. For example, the gas barrier layer is preferably a polyester resin from the viewpoint of gas barrier properties.

  The weld layer is preferably a polyolefin resin from the viewpoint of weldability, and among them, an acid-modified polyolefin resin is more preferable from the viewpoint of insulation. Further, among the acid-modified polyolefin resins, it is preferable to use polyethylene graft-modified with an unsaturated carboxylic acid because the insulating property is improved.

  In addition, it is also preferable from the viewpoint of heat resistance and insulation that the weld layer is polypropylene graft-modified with an unsaturated carboxylic acid.

  Further, the reinforcing sheet is preferably formed so as to be slightly larger than the electrolyte membrane, and the outer peripheral edge portions located outside the electrolyte membrane are welded to each other. By comprising in this way, the gasket conventionally installed on the electrolyte membrane can be installed on a reinforcement sheet. For this reason, it becomes possible to make small the electrolyte membrane in which an expensive material is used, and cost can be reduced.

  A polymer electrolyte fuel cell according to the present invention is made to solve the above-described problems, and includes any one of the above electrolyte membrane-electrode assembly with a reinforcing sheet, the catalyst layer, and the gas diffusion layer. Gaskets installed on the reinforcing sheet so as to surround each electrode, and separators installed on the electrodes and the gasket, respectively.

  By being configured in this way, the following effects can be obtained. That is, since the electrolyte membrane corresponding to the gap portion between the catalyst layer and the gasket is constrained by the reinforcing sheet, expansion / contraction can be suppressed, and as a result, damage to the electrolyte membrane can be prevented. . In addition, the reinforcing sheet is composed of two layers, a gas barrier layer and a welding layer, and the gas barrier layer is disposed on the separator side, so that the fuel gas supplied from the gas flow path of each separator to each gas diffusion layer and Oxidant gas can be prevented from permeating through the reinforcing sheet, and fuel gas and oxidant gas can be prevented from leaking outside through the reinforcing sheet.

  According to the present invention, there are provided an electrolyte membrane-electrode assembly with a reinforcing sheet and a solid polymer fuel cell using the same, which can prevent damage to the electrolyte membrane while having sufficient gas barrier properties. Is an issue.

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-electrode assembly with a reinforcement sheet which concerns on this embodiment.

  Hereinafter, embodiments of 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 catalyst layer 3 having a rectangular shape in plan view is provided on the upper and lower surfaces of the electrolyte membrane 2 as an electrolyte. It is formed slightly smaller than the film 2. 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.

  A rectangular gas diffusion layer 4 in plan view is formed on each catalyst layer 3 of the electrolyte membrane-catalyst layer assembly 10. The catalyst layer 3 and the gas diffusion layer 4 constitute an electrode E. The gas diffusion layer 4 is substantially the same size as the catalyst layer 3 or is slightly smaller than the catalyst layer 3. The distance B (see FIG. 3) from the outer peripheral edge of the gas diffusion layer 4 to the outer peripheral edge of the catalyst layer 3 is preferably 0 to 5 mm. In addition, what formed the gas diffusion layer 4 on each catalyst layer 3 of the electrolyte membrane-catalyst layer assembly 10 in this way is called an electrolyte membrane-electrode assembly 20.

  A frame-shaped reinforcing sheet 5 having an opening 51 at the center is welded to the upper and lower surfaces of the electrolyte membrane-electrode assembly 20. Each reinforcing sheet 5 includes a gas barrier layer 52 that prevents permeation of fuel gas and oxidant gas used for power generation of the fuel cell, and a weld layer 53 that is welded to the electrolyte membrane-catalyst layer assembly 10. The weld layer 53 is disposed so as to face the electrolyte membrane-electrode assembly 20 side. The thickness of the gas barrier layer 52 is preferably 5 to 50 μm, and the thickness of the weld layer 53 is preferably 1 to 50 μm. In a state where the reinforcing sheet 5 is welded to the electrolyte membrane-electrode assembly 20, the gas diffusion layer 4 is exposed from the opening 51 of the reinforcing sheet 5 except for the outer peripheral edge portion 41, and the gas diffusion layer 4 The reinforcing sheet 5 is welded on the outer peripheral edge 41 and the outer peripheral edge 21 of the electrolyte membrane 2, or on the outer peripheral edge 31 of the catalyst layer 3 when the catalyst layer 3 is larger than the gas diffusion layer 4. In addition, it is preferable that the distance A (refer FIG. 3) from the outer periphery of the gas diffusion layer 4 to the inner periphery of the reinforcement sheet 5 shall be 1-10 mm. The reinforcing sheet 5 is formed to be slightly larger than the electrolyte membrane 2, and the outer peripheral edge portions 55 of the reinforcing sheets 5 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 5 to the outer peripheral edge of the electrolyte membrane 2 is preferably 1 to 100 mm. As described above, the electrolyte membrane-electrode assembly 20 to which the reinforcing sheet 5 is welded 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 each 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 4.

  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 include a perfluorosulfonic acid-based fluorine ion exchange resin, more specifically, a perfluorocarbonsulfonic acid-based resin in which the C—H bond of a hydrocarbon ion-exchange membrane is substituted with fluorine. Examples include 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 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 5 is composed of a gas barrier layer 52 and a welded layer 53. The gas barrier layer 52 is made of polyester, polyamide, polyimide, polymethyl tempene, 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 53 is preferably a polyolefin-based 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 4, various gas diffusion layers constituting a fuel electrode and an air electrode can be used, and a porous fuel gas and an oxidant gas are efficiently supplied to the catalyst layer 3. It is made of a conductive substrate. Examples of the porous conductive substrate include carbon paper and carbon cloth.

  Gasket 6 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, polyethylene terephthalate sheet, Teflon (registered trademark) sheet, silicon rubber sheet, etc. Can be illustrated.

  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 material 81 include polyimide, polyethylene terephthalate, polyparvanic acid aramid, polyamide (nylon), polysulfone, polyethersulfone, polyphenylene sulfide, polyether ether ketone, polyetherimide, polyarylate, and polyethylene naphthalate. And the like. In addition, 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 prepared as described above is arranged so that the catalyst layer 3 faces the electrolyte membrane 2 (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. 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 (FIG. 4B). Since the catalyst layer 3 is 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.

  Then, the gas diffusion layer 4 is laminated on the catalyst layer 3 of the electrolyte membrane-catalyst layer assembly 10 by thermocompression bonding, thereby completing the electrolyte membrane-electrode assembly 20 (FIG. 4C).

  Next, the reinforcing sheet 5 is attached to the electrolyte membrane-electrode assembly 20 thus formed (FIG. 4D). This process will be described with reference to FIG. FIG. 5 is a plan view showing a process of attaching the reinforcing sheet 5 to the electrolyte membrane-electrode assembly 20. As shown in FIG. 5, the two reinforcing sheets 5 made of the above-described materials are overlapped, and the remaining three sides are left welded together. As a result, the two reinforcing sheets 5 form 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, iron welding, ultrasonic welding, etc. it can.

  When the bag body is formed by the reinforcing sheet 5, an easily removable region 54 that is slightly smaller than the catalyst layer 3 of the electrolyte membrane-electrode assembly 20 is then formed in the central portion of each reinforcing sheet 5 constituting the bag body ( FIG. 5B). The easy-removal region 54 refers to a region that can be easily removed. For example, the easy-removal region 54 can be formed by making a perforation in the outer peripheral edge or making a cut while leaving only a part. The electrolyte membrane-electrode assembly 20 is inserted into the bag body in which the easy-removable region 54 is formed in this way from the left side which is not welded and moved to a predetermined position (FIG. 5C). The predetermined position refers to a position where the gas diffusion layer 4 of the electrolyte membrane-electrode assembly 20 is opposed to the easy removal region 54 except for the outer peripheral edge portion 41.

  After the electrolyte membrane-electrode assembly 20 is inserted into the bag body and moved to a predetermined position, the perforation at the outer peripheral edge of the easy-removal region 54 is cut and the easy-removal region 54 is removed from each reinforcing sheet 5, An opening 51 is formed at the center of each reinforcing sheet 5 (FIG. 5D). When the easy removal regions 54 are thus removed from the reinforcing sheets 5 and the openings 51 are formed, the gas diffusion layer 4 of the electrolyte membrane-electrode assembly 20 is removed from the openings 51 except for the outer peripheral edge 41. It will be exposed. In this state, the reinforcing sheet 5 is welded by a known method so that the reinforcing sheet 5 is not welded, so that the reinforcing sheet 5 has the outer peripheral edge 41 of the gas diffusion layer 4 of the electrolyte membrane-electrode assembly 20 or the like. While being welded to the outer peripheral edge portion 21 of the electrolyte membrane 2, the outer peripheral edge portions 55 of the reinforcing sheet 5 are welded to each other outside the electrolyte membrane 2. Through the above steps, the electrolyte membrane-electrode assembly with the reinforcing sheet is completed (FIGS. 5E and 4D).

  Returning to FIG. 4, the description of the method for producing the polymer electrolyte fuel cell 1 will be continued. A gasket 6 is disposed on the reinforcing sheet 5 so as to surround the electrode E including the catalyst layer 3 and the gas diffusion layer 4 of the electrolyte membrane-electrode assembly with the reinforcing sheet. The separator 7 is disposed on the electrode E and the gasket 6 so that the gas flow path 71 faces the gas diffusion layer 4, and is sandwiched by the separator 7 so that the electrode E and the separator 7 are electrically connected. Thus, the polymer electrolyte fuel cell 1 is completed (FIG. 4E). 1 and 4, it is described that the gas diffusion layer 4 and the separator 7 are not in contact with each other. However, since the reinforcing sheet 5 is actually a very thin film, the gas diffusion is performed to such an extent that current can be collected. Layer 4 and separator 7 are in contact.

  As described above, in this embodiment, the reinforcing sheet 5 is installed on the outer peripheral edge 21 of the electrolyte membrane 2 where the catalyst layer 3 is not formed. For this reason, the electrolyte membrane 2 corresponding to the gap between the catalyst layer 3 and the gasket 6 is restrained by the reinforcing sheet 5. Therefore, the electrolyte membrane 2 is prevented from expanding and contracting due to repeated wet and dry states, and as a result, damage to the electrolyte membrane 2 can be prevented. In addition, in order to generate power in this polymer electrolyte fuel cell, fuel gas is supplied from the gas flow path 71 of one separator 7 and oxidant gas is supplied from the gas flow path 71 of the other separator 7. Since the reinforcing sheet 5 partially resting on the outer peripheral edge portion 41 of the layer 4 has the gas barrier layer 52 on the separator 7 side to which the fuel gas or the oxidant gas is supplied, the fuel gas and the oxidant gas Can be eliminated through the reinforcing sheet 5.

  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 said embodiment, although the manufacturing method of once using the reinforcing sheet 5 as a bag body and inserting the electrolyte membrane electrode assembly 20 is employ | adopted, it is not specifically limited to this. For example, by arranging and welding the reinforcing sheets 5 in which the openings 51 are formed in advance on both surfaces of the electrolyte membrane-electrode assembly 20 so that the welding layer 53 faces the electrolyte membrane-electrode assembly 20, respectively. You may produce the electrolyte membrane electrode assembly 20 with a reinforcement sheet.

  Moreover, in the said embodiment, although the reinforcement sheet 5 is comprised from 2 layers of the gas barrier layer 52 and the welding layer 53, it can also be set as the structure of 3 or more layers. For example, in order to improve the adhesion between the gas barrier layer 52 and the welding layer 53, an adhesion promoting layer (not shown) made of isocyanate, polyethyleneimine, polyurethane, polybutadiene or the like is provided between the gas barrier layer 52 and the welding layer 53. ) Can also be formed.

  Moreover, in the said embodiment, although the electrolyte membrane 2, the catalyst layer 3, the gas diffusion layer 4, etc. which comprise the polymer electrolyte fuel cell 1 are all formed in the planar view rectangular shape, especially a shape is limited. Instead, for example, it can be formed in a circular shape in plan view.

  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
An electrode E composed of the catalyst layer 3 and the gas diffusion layer 4 was produced as follows. First, platinum catalyst-supported carbon (platinum supported amount: 45.7 wt%, TEC10E50E manufactured by Tanaka Kikinzoku), 1-butanol 10 g, 3-butanol 10 g, fluororesin (5 wt% Nafion binder, manufactured by DuPont) 20 g and water 6 g Then, these were stirred and mixed with a disperser to prepare an ink composition for forming a catalyst. Next, the prepared ink was applied to carbon paper (Toray, TGP-H-090, thickness 280 μm) as the gas diffusion layer 4 so that the platinum weight after drying the catalyst layer was 0.4 mg / cm ^2. Then, a gas diffusion electrode was produced.

  Next, NRE212CS (manufactured by Dupont) having a thickness of 53 μm cut to a size of 63 × 63 mm is prepared as the electrolyte membrane 2, and the catalyst layer 3 has the electrode E cut to 60 × 60 mm on each side. An electrode E is formed on both surfaces of the electrolyte membrane 2 by placing the centers so as to face the electrolyte membrane 2 and hot pressing under conditions of 135 ° C., 5.0 MPa, 150 seconds, and the electrolyte membrane-electrode assembly 20 was produced. The thickness of the electrode E was 300 μm. The layer structure at this time is gas diffusion layer 4 / catalyst layer 3 / electrolyte membrane 2 / catalyst layer 3 / gas diffusion layer 4.

  Subsequently, a reinforcing sheet 5 was produced. As the gas barrier layer 52 of the reinforcing sheet 5, biaxially stretched polyethylene naphthalate (manufactured by Teijin Limited, Teonex, 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 melt extrusion to form a weld layer 53. The reinforcing sheet 5 was cut to a size of 80 × 80 mm, and an opening 51 having a size of 50 × 50 mm was formed at the center. Then, the reinforcing sheet 5 is placed centering on both surfaces of the electrolyte membrane-electrode assembly 20 and hot pressed under the conditions of 130 ° C., 1.0 MPa, 30 seconds, so that the reinforcing sheet 5 is electrolyte membrane-electrode assembly. 20 to prepare an electrolyte membrane-electrode assembly with a reinforcing sheet.

(Example 2)
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 applied to a polyester film (Toray, X44, 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. .

  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, carbon paper (TGP-H-090, manufactured by Toray Industries, Inc., thickness 280 μm) cut to a size of 60 × 60 mm is prepared as the gas diffusion layer 4, and each catalyst layer of the electrolyte membrane-catalyst layer assembly 10 is prepared. 3 was laminated. Thereby, an electrolyte membrane-electrode assembly 20 having a layer configuration of gas diffusion layer 4 / catalyst layer 3 / electrolyte membrane 2 / catalyst layer 3 / gas diffusion layer 4 was produced.

  Subsequently, a reinforcing sheet 5 was produced. As the gas barrier layer 52 of the reinforcing sheet 5, biaxially stretched polyethylene naphthalate (manufactured by Teijin Limited, Teonex, 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 melt extrusion to form a weld layer 53. The reinforcing sheet 5 was cut to a size of 80 × 80 mm, and an opening 51 having a size of 50 × 50 mm was formed at the center. Then, the reinforcing sheet 5 is placed centering on both surfaces of the electrolyte membrane-electrode assembly 20 and hot pressed under the conditions of 130 ° C., 1.0 MPa, 30 seconds, so that the reinforcing sheet 5 is electrolyte membrane-electrode assembly. 20 to prepare an electrolyte membrane-electrode assembly with a reinforcing sheet.

(Example 3)
The same material, dimensions, and manufacturing method as in Example 1 described above, except that the material of the reinforcing sheet 5 is different and the conditions of hot pressing when the reinforcing sheet 5 is welded to the electrolyte membrane-electrode assembly 20 are different. Thus, an electrolyte membrane-electrode assembly with a reinforcing sheet was produced.

  The reinforcing sheet 5 of Example 3 will be described. First, as the gas barrier layer 52, biaxially stretched polyethylene terephthalate (manufactured by Teijin Ltd., Teflex, thickness 20 μm) was used. An unsaturated carboxylic acid graft-modified polyethylene was extruded to a thickness of 30 μm on this polyethylene terephthalate by a melt extrusion method to form a weld layer 53. The reinforcing sheet 5 is placed centering on both surfaces of the electrolyte membrane-electrode assembly 20 and hot pressed under the conditions of 100 ° C., 1.0 MPa, and 30 seconds, whereby the reinforcing sheet 5 is electrolyte membrane-electrode assembly 20. To prepare an electrolyte membrane-electrode assembly with a reinforcing sheet.

Example 4
Except for the point that the material of the reinforcing sheet 5 is different and the condition of hot press when the reinforcing sheet 5 is welded to the electrolyte membrane-electrode assembly 20 are different, the same material, dimensions, and manufacturing method as those of the above-described Example 2. Then, an electrolyte membrane-electrode assembly with a reinforcing sheet was produced.

  The reinforcing sheet 5 of Example 4 will be described. First, as the gas barrier layer 52, biaxially stretched polyethylene terephthalate (manufactured by Teijin Ltd., Teflex, thickness 20 μm) was used. An unsaturated carboxylic acid graft-modified polyethylene was extruded to a thickness of 30 μm on this polyethylene terephthalate by a melt extrusion method to form a weld layer 53. Then, the reinforcing sheet 5 is placed centering on both surfaces of the electrolyte membrane-electrode assembly 20 and hot pressed under the conditions of 100 ° C., 1.0 MPa, 30 seconds, so that the reinforcing sheet 5 is electrolyte membrane-electrode assembly. 20 to prepare an electrolyte membrane-electrode assembly with a reinforcing sheet.

(Example 5)
The electrolyte membrane with a reinforcing sheet is the same material, dimensions, and manufacturing method as in Example 1 except that polyimide (manufactured by Toray DuPont, Kapton, thickness 13 μm) is used as the gas barrier layer 52 of the reinforcing sheet 5. -An electrode assembly was prepared.

(Example 6)
The electrolyte membrane with a reinforcing sheet is the same material, dimensions, and manufacturing method as in Example 2 except that polyimide (manufactured by Toray DuPont, Kapton, thickness 13 μm) is used as the gas barrier layer 52 of the reinforcing sheet 5. -An electrode assembly was prepared.

(Comparative Example 1)
An electrolyte membrane-electrode assembly was produced using the same materials, dimensions, and manufacturing method as in Example 1 except that the reinforcing sheet 5 was not installed and the size of the electrode E was 50 × 50 mm.

(Comparative Example 2)
An electrolyte membrane-electrode assembly with a reinforcing sheet is the same material, dimensions, and manufacturing method as in Example 1 except that the reinforcing sheet 5 is composed only of the welded layer 53 and does not have the gas barrier layer 52. Was made. In addition, the reinforcement sheet 5 of this comparative example 2 comprised the reinforcement sheet 5 only by the welding layer 53 which consists of a polypropylene (Toray Industries, Treffan, thickness 30 micrometers).

(Comparative Example 3)
Except for the point that the reinforcing sheet 5 is composed only of the gas barrier layer 52 and does not have the welded layer 53, and the point that the reinforcing sheet 5 is laminated without being welded to the electrolyte membrane-electrode assembly, the above-described implementation is performed. An electrolyte membrane-electrode assembly with a reinforcing sheet was produced using the same material and production method as in Example 1. The reinforcing sheet 5 of Comparative Example 3 was composed of only a gas barrier layer 52 of biaxially stretched polyethylene naphthalate (manufactured by Teijin Ltd., Teonex, thickness: 12 μm).

(Evaluation method)
Regarding the electrolyte membrane-electrode assembly with reinforcing sheet of Examples 1 to 6, the electrolyte membrane-electrode assembly of Comparative Example 1, and the electrolyte membrane-electrode assembly with reinforcing sheet of Comparative Examples 2 and 3, gasket 6 and separator 7 The polymer electrolyte fuel cells were respectively prepared and subjected to a load fluctuation cycle test. The results are shown in Table 1. For the electrolyte membrane-electrode assembly of Comparative Example 1, a gasket was placed 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 shown in Table 1, as a result of the load fluctuation cycle test, the voltage of the fuel cells of Example 1 and Example 2 decreases even after 1600 hours and the fuel cells of Examples 3 to 6 even after 1000 hours. In addition, when the electrolyte membrane of each fuel cell was confirmed after this load fluctuation cycle test, no damage was found in any electrolyte membrane 2. On the other hand, the fuel cell of Comparative Example 1 was confirmed to have a voltage drop after 300 hours and the fuel cell of Comparative Example 2 had passed 400 hours, and both Comparative Example 1 and Comparative Example 2 were tested after the load fluctuation cycle test. Damage to the electrolyte membrane 2 was confirmed visually. In Comparative Example 3, since the gas leak was large, measurement by the load fluctuation cycle test was impossible, and the durability time was 0 hour. Moreover, 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 6 was 1 mA / cm ² or less, whereas that of the fuel cells of Comparative Examples 1 to 3 was The amount of leakage current was 20 mA / cm ² or more, and gas leakage due to breakage of the electrolyte membrane or poor sealing performance of the reinforcing sheet 5 was observed.

  As described above, in the polymer electrolyte fuel cells of Examples 1 to 6, since the endurance time is increased, the problem of electrolyte membrane breakage was solved by using the polymer electrolyte fuel cell of the present invention. I understand that.

DESCRIPTION OF SYMBOLS 1 Polymer electrolyte fuel cell 2 Electrolyte membrane 3 Catalyst layer 4 Gas diffusion layer 5 Reinforcement sheet 51 Opening 52 Gas barrier layer 53 Welding layer 6 Gasket 7 Separator E Electrode

Claims (8)

A solid polymer electrolyte membrane;
Catalyst layers respectively formed on both surfaces excluding the outer peripheral edge of the electrolyte membrane;
A gas diffusion layer formed on each catalyst layer excluding each outer peripheral edge, and
A gas barrier layer for preventing permeation of a fuel gas and an oxidant gas and a weld for welding to the electrolyte membrane-electrode assembly, which are welded to both surfaces of the electrolyte membrane-electrode assembly comprising the electrolyte membrane, the catalyst layer, and the gas diffusion layer, respectively. A reinforcing sheet having a layer,
Each of the reinforcing sheets has a frame shape having an opening in the center, and the outer peripheral edge of the gas diffusion layer and the catalyst layer are exposed from the opening except for the outer peripheral edge. An electrolyte membrane-electrode assembly with a reinforcing sheet, which is welded onto the outer peripheral edge and the outer peripheral edge of the electrolyte membrane. The electrolyte membrane-electrode assembly with a reinforcing sheet according to claim 1, wherein the distance from the outer peripheral edge of the gas diffusion layer to the outer peripheral edge of the catalyst layer is greater than 0 mm and 5 mm or less.   The electrolyte membrane-electrode assembly according to claim 1 or 2, wherein the gas barrier layer is a polyester resin.   The electrolyte membrane-electrode assembly with a reinforcing sheet according to any one of claims 1 to 3, wherein the welding layer is a polyolefin-based resin.   The electrolyte membrane-electrode assembly with a reinforcing sheet according to claim 4, wherein the polyolefin resin is an acid-modified polyolefin resin.   The electrolyte membrane-electrode assembly with a reinforcing sheet according to claim 5, wherein the acid-modified polyolefin resin is polyethylene graft-modified with an unsaturated carboxylic acid.   The electrolyte membrane-electrode assembly with a reinforcing sheet according to claim 5, wherein the acid-modified polyolefin-based resin is polypropylene graft-modified with an unsaturated carboxylic acid. An electrolyte membrane-electrode assembly with a reinforcing sheet according to any one of claims 1 to 7,
Gaskets respectively installed on the reinforcing sheet so as to surround each electrode composed of the catalyst layer and the gas diffusion layer;
Separators respectively installed on the electrodes and gaskets;
A solid polymer fuel cell comprising:

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