JP5791222B2 - Catalyst layer with reinforcing membrane-electrolyte membrane laminate, membrane electrode assembly with reinforcing membrane, and polymer electrolyte fuel cell - Google Patents

Description

  The present invention relates to a catalyst layer-electrolyte membrane laminate with a reinforcing membrane, a membrane electrode assembly with a reinforcing membrane, and a polymer electrolyte fuel cell.

  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.

  In this polymer electrolyte fuel cell, a solid polymer electrolyte membrane having proton conductivity is used, and a catalyst layer and a conductive porous substrate 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 conductive porous base material may be enclosed, and also this was pinched | interposed with the separator (refer FIG. 3 or FIG. 4 of patent document 1). ). However, the outer peripheral edge of the electrolyte membrane on which the gasket is installed is a portion that does not contribute to power generation, and generally an expensive electrolyte membrane cannot be effectively used. For this reason, a polymer electrolyte fuel cell has been proposed in which a reinforcement membrane extending outward from the outer peripheral edge of the membrane electrode assembly is separately provided and a gasket is disposed on the reinforcement membrane (see FIG. 1 and Patent Document 1). (See FIG. 2). In addition, as in Patent Document 2, a reinforcing membrane may be provided in order to suppress expansion and contraction of the electrolyte membrane portion that is not suppressed by each electrode.

JP 2004-47230 A Japanese Patent No. 3052536

  As described above, a polymer electrolyte fuel cell having a reinforcing membrane has been proposed for various reasons. However, when such a polymer electrolyte fuel cell is operated for a long time, there arises a problem that the reinforcing membrane peels off. Sometimes.

  Therefore, an object of the present invention is to provide a catalyst layer-electrolyte membrane laminate with a reinforcing membrane, a membrane electrode assembly with a reinforcing membrane, and a polymer electrolyte fuel cell that can prevent the peeling of the reinforcing membrane. .

As a result of earnestly studying the cause of the problem that the reinforcing membrane of the polymer electrolyte fuel cell having the auxiliary membrane is peeled off, the present inventors have made a reaction between hydrogen peroxide and a catalyst such as platinum. Was found to be the cause. That is, depending on the operating conditions of the polymer electrolyte fuel cell, the reduction of oxygen at the cathode (air electrode) may be stopped by a two-electron reaction and hydrogen peroxide (H ₂ O ₂ ) may be generated. Also in the anode (fuel electrode), oxygen that has passed through the electrolyte membrane and diffused into the anode may react with hydrogen adsorbed on the catalyst to generate hydrogen peroxide. The produced hydrogen peroxide is dissolved in the produced water produced from hydrogen and oxygen at the cathode during operation of the polymer electrolyte fuel cell. This generated water tends to stay at the outer peripheral edge of the electrode, particularly the catalyst layer, and the generated water evaporates during operation, but hydrogen peroxide has a high boiling point, and therefore tends to hardly evaporate because it has a high boiling point. Thus, the hydrogen peroxide staying at the outer peripheral edge of the catalyst layer of the electrode may be radically decomposed in the presence of the catalyst in the catalyst layer, thereby attacking the reinforcing film and peeling the reinforcing film.

  Therefore, the reinforcing layer-attached catalyst layer-electrolyte membrane laminate according to the present invention is formed on both surfaces of an ion conductive polymer electrolyte membrane and the electrolyte membrane, and includes carbon particles, an ion conductive polymer electrolyte, and a catalyst. Both sides of the catalyst layer-electrolyte membrane laminate composed of the electrolyte membrane and the catalyst layer so that the catalyst layer has an opening in the center and the inner peripheral edge adheres to the outer peripheral edge of the catalyst layer And the catalyst layer does not include a catalyst in the outer peripheral edge portion.

  As described above, in the catalyst layer-electrolyte membrane laminate with a reinforcing film according to the present invention, the outer peripheral edge portion of the catalyst layer in which the generated water in which hydrogen peroxide is dissolved easily retains no catalyst. For this reason, even if generated water in which hydrogen peroxide is dissolved stays at the outer peripheral edge of the catalyst layer, the hydrogen peroxide is not radically decomposed and does not attack the reinforcing membrane. As a result, the problem that the reinforcing film peels can be solved.

  The catalyst layer-electrolyte membrane laminate with the reinforcing membrane can take various configurations. For example, the reinforcing membrane is formed to be slightly larger than the electrolyte membrane, and the outer peripheral edge of the reinforcing membrane outside the electrolyte membrane. It can also be set as the structure which adhered each other. According to this configuration, it is possible to install a gasket at a portion where the outer peripheral edge portions of the reinforcing membrane are bonded to each other, and thus it is possible to omit a portion of the electrolyte membrane that has been provided with a conventional gasket that does not contribute to power generation. .

  Moreover, you may further provide the fibrous substance extended over between the outer periphery part of the said catalyst layer, and the inner periphery part of a reinforcement film | membrane. The anchor effect of the fibrous material can more reliably prevent the reinforcing film from peeling off.

  The reinforcing membrane preferably has an adhesive layer that adheres to the catalyst layer and a gas barrier layer that prevents permeation of fuel gas and oxidant gas. According to this configuration, the reinforcing membrane can more reliably adhere to the catalyst layer and prevent gas permeation.

  The first membrane electrode assembly with a reinforcing membrane according to the present invention includes any one of the above-described catalyst layer-electrolyte membrane laminate with a reinforcing membrane, and a conductive porous substrate formed on each of the catalyst layers. And.

  According to this structure, since the catalyst layer-electrolyte membrane laminated body with a reinforcement film | membrane mentioned above is provided, peeling of a reinforcement film | membrane can be prevented. In addition, the said conductive porous base material can also be formed on the catalyst layer exposed from the inside of the opening part of each reinforcement film | membrane.

  A second membrane electrode assembly with a reinforcing membrane according to the present invention is formed on both surfaces of an ion conductive polymer electrolyte membrane and the electrolyte membrane, and includes carbon particles, an ion conductive polymer electrolyte, and a catalyst. The catalyst layer, the conductive porous substrate formed on each of the catalyst layers, and an opening at the center, and the inner peripheral edge adheres to the outer peripheral edge of the conductive porous substrate. A reinforcing membrane adhered to both surfaces of a membrane electrode assembly composed of the electrolyte membrane, the catalyst layer, and a conductive porous substrate, and the catalyst layer is made of the conductive porous substrate. No catalyst is included in the outer peripheral edge facing the outer peripheral edge.

  As described above, in the second membrane electrode assembly with a reinforcing membrane according to the present invention, the outer peripheral edge portion of the catalyst layer in which the generated water in which hydrogen peroxide is dissolved easily retains no catalyst. For this reason, even if generated water in which hydrogen peroxide is dissolved stays at the outer peripheral edge of the catalyst layer, the hydrogen peroxide is not radically decomposed and does not attack the reinforcing membrane. As a result, the problem that the reinforcing film peels can be solved.

  The membrane electrode assembly with the second reinforcing membrane can have various configurations. For example, a fibrous substance extending between the outer peripheral edge of the conductive porous substrate and the inner peripheral edge of the reinforcing membrane. May be further provided. The anchor effect of the fibrous material can more reliably prevent the reinforcing film from peeling off.

  A polymer electrolyte fuel cell according to the present invention includes a membrane electrode assembly with any of the above-described reinforcing membranes, a gasket installed on each of the reinforcing membranes, and a membrane electrode junction with a reinforcing membrane on which the gaskets are installed. And a separator installed to sandwich the body from both sides.

  Since this polymer electrolyte fuel cell has the above-mentioned membrane electrode assembly with a reinforcing membrane, it is possible to prevent peeling of the reinforcing membrane.

  ADVANTAGE OF THE INVENTION According to this invention, the catalyst layer-electrolyte membrane laminated body with a reinforcement film which can prevent peeling of a reinforcement film, a membrane electrode assembly with a reinforcement film, and a polymer electrolyte fuel cell can be provided.

FIG. 1 is a front sectional view showing an embodiment of a polymer electrolyte fuel cell according to the present invention. FIG. 2 is a plan view showing an embodiment in which the separator and gasket of the polymer electrolyte fuel cell according to the present invention are omitted. FIG. 3 is an enlarged front sectional view showing details of the outer peripheral edge of the membrane electrode assembly with a reinforcing membrane according to the present embodiment. FIG. 4 is an explanatory view showing a method for producing a polymer electrolyte fuel cell according to this embodiment. FIG. 5 is an explanatory view showing a method for producing a transfer sheet for forming a catalyst layer according to this embodiment. FIG. 6 is an explanatory view showing a method for producing a reinforcing layer-attached catalyst layer-electrolyte membrane laminate according to this embodiment. FIG. 7 is a front cross-sectional view showing another embodiment of the polymer electrolyte fuel cell according to the present invention. FIG. 8 is a front sectional view showing still another embodiment of the polymer electrolyte fuel cell according to the present invention.

  Hereinafter, embodiments of a catalyst layer-electrolyte membrane laminate, a membrane electrode assembly with a reinforcement membrane, and a polymer electrolyte fuel cell according to the present invention will be described with reference to the drawings.

  As shown in FIGS. 1 and 2, the polymer electrolyte fuel cell 1 includes a catalyst layer-electrolyte membrane laminate 10 composed of an electrolyte membrane 2 and a catalyst layer 3, and an outer side from the catalyst layer-electrolyte membrane laminate 10. And a conductive porous substrate 5 formed on the catalyst layer 3. The polymer electrolyte fuel cell 1 also includes a gasket 6 installed on the reinforcing membrane 4 and a separator 7 for sandwiching them. Hereinafter, each member will be described in detail.

  The electrolyte membrane 2 has a rectangular shape in plan view, and a catalyst layer 3 that is slightly smaller than the electrolyte membrane 2 is formed on both surfaces of the electrolyte membrane 2. The catalyst layer 3 formed on both surfaces of the electrolyte membrane 2 is referred to as a catalyst layer-electrolyte membrane laminate 10. The catalyst layer 3 includes an outer peripheral edge portion 31 to which an inner peripheral edge portion of a reinforcing film 4 described later is bonded, and a central portion 32 exposed from the opening 41 of the reinforcing film 4. Further, 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 portion 21 of the electrolyte membrane 2, but as shown in FIG. It can also be formed in the same size as 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 0-5 mm. The thickness of the electrolyte membrane 2 is usually about 20 to 250 μm, preferably about 20 to 80 μm, and the thickness of the catalyst layer 3 is not limited, but is usually about 1 to 100 μm, preferably 2 to 50 μm. Degree.

  And the frame-shaped reinforcement film | membrane 4 which has the opening part 41 in the center is adhere | attached on the upper surface and lower surface of this catalyst layer-electrolyte membrane laminated body 10, respectively. The reinforcing film 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 an adhesive layer 43 that adheres to the catalyst layer-electrolyte film laminate 10. The layer 43 is directed to the catalyst layer-electrolyte membrane laminate 10 side. The thickness of the gas barrier layer 42 is preferably 5 to 50 μm, and the thickness of the adhesive layer 43 is preferably 1 to 50 μm. In a state where the reinforcing film 4 is bonded to the catalyst layer-electrolyte membrane laminate 10, the inner peripheral edge portion of the reinforcing film 4 is bonded to the outer peripheral edge portion 31 of the catalyst layer 3, and the catalyst layer 3 is formed from the opening 41. A central portion 32 that is a portion excluding the outer peripheral edge portion 31 is exposed. 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 film | membrane 4 shall be 1-10 mm.

The reinforcing membrane 4 is formed to be slightly larger than the electrolyte membrane 2, adheres onto the outer peripheral edge 21 of the electrolyte membrane 2, and each reinforcing membrane 4 protrudes from the electrolyte membrane 2 outside the electrolyte membrane 2. The outer peripheral edge portions 45 are bonded to each other. The reinforcing film 4 can also be formed in the same size as the electrolyte film 2. The distance D (see FIG. 3) from the outer peripheral edge of the reinforcing membrane 4 to the outer peripheral edge of the electrolyte membrane 2 is preferably 0 to 100 mm. Thus, what the reinforcement film | membrane 4 adhere | attached on the catalyst layer-electrolyte membrane laminated body 10 is equivalent to the catalyst layer-electrolyte membrane laminated body with a reinforcement film of this invention.

  A conductive porous substrate 5 having a rectangular shape in plan view is formed on the central portion 32 of the catalyst layer 3 exposed from the opening 41 of the reinforcing membrane 4. The distance A (see FIG. 3) from the outer peripheral edge of the conductive porous substrate 5 to the inner peripheral edge of the reinforcing film 4 is preferably 0 to 5 mm. In this way, the conductive porous substrate 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 referred to as a membrane electrode assembly 20. In addition, what the reinforcement film | membrane 4 adhere | attached on the membrane electrode assembly 20 like this embodiment is equivalent to the membrane electrode assembly with a reinforcement film | membrane of this 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 conductive porous substrate 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 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 contains carbon particles supporting catalyst particles and a hydrogen ion conductive polymer electrolyte in the central portion 32. As the hydrogen ion conductive polymer electrolyte, the same material as that used for the electrolyte membrane 2 described above can be used.

  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.

  The carbon particles are not limited as long as they have electrical conductivity, and known or commercially available carbon particles can be widely used. For example, carbon black, graphite, activated carbon, or the like can be used alone or in combination. Examples of carbon black include channel black, furnace black, ketjen black, acetylene black, and lamp black. The arithmetic average particle diameter of the carbon particles is usually about 5 nm to 200 nm, preferably about 20 to 80 nm. The average particle size of the carbon particles can be measured by, for example, a particle size distribution measuring device LA-920: manufactured by Horiba, Ltd.

  Further, the catalyst layer 3 contains the above-described carbon particles and hydrogen ion conductive polymer electrolyte in the outer peripheral edge portion 31. The carbon particles in the outer peripheral edge 31 do not carry catalyst particles, that is, the catalyst layer 3 in the outer peripheral edge 31 does not contain catalyst particles such as platinum or a platinum compound.

  The reinforcing film 4 is composed of a gas barrier layer 42 and an adhesive layer 43. The gas barrier layer 42 is made of polyester, polyamide, polyimide, polymethyl tempen having barrier properties against water vapor, water, fuel gas and oxidant gas, Polyphenylene 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 adhesive layer 43 is preferably a polyolefin resin, such as 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. In addition, other materials similar to the electrolyte membrane 2 such as a perfluorocarbon sulfonic acid-based fluorine ion exchange resin can be mentioned. Specifically, “Nafion” (registered trademark) manufactured by DuPont, Asahi Glass Co., Ltd. “Flemion” (registered trademark) manufactured by Asahi Kasei Co., Ltd., “Aciplex” (registered trademark) manufactured by Asahi Kasei Co., Ltd., “Gore Select” (registered trademark) manufactured by Gore, Inc., and the like.

  The conductive porous substrate 5 is well-known, and various conductive porous substrates constituting an anode (fuel electrode) and a cathode can be used, and a fuel layer and an oxidant gas which are fuels can be efficiently used as a catalyst layer. 3 is made of a porous 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. The catalyst layer forming transfer sheet 8 is one in which the transferred catalyst layer 3 is formed on a transfer substrate 81.

  Here, a method for producing the transfer sheet 8 for forming a catalyst layer will be described. First, the first catalyst paste is prepared by mixing and dispersing the carbon particles supporting the catalyst particles and the hydrogen ion conductive polymer electrolyte in an appropriate solvent. This first catalyst paste is used in the central portion 32 of the catalyst layer 3. For the outer peripheral edge 31 of the catalyst layer 3, carbon particles and hydrogen ion conductive polymer electrolyte are mixed and dispersed in an appropriate solvent to form a second catalyst paste. Unlike the first catalyst paste, the second catalyst paste does not contain catalyst particles.

  Then, the first catalyst paste is applied and dried on the transfer substrate 81 so that the formed catalyst layer 3 has a desired film thickness, thereby forming the central portion 32 of the catalyst layer 3, and the second The outer peripheral edge portion 31 is formed by coating and drying the catalyst paste around the central portion 32. If necessary, each catalyst paste is applied onto the transfer substrate 81 via a release layer. Thereby, the releasability of the transfer substrate 81 from the catalyst layer 3 can be further improved. As the release layer, for example, a surface made of a known wax or a fluororesin can be provided on the surface of the transfer substrate 81 by coating, but a vapor deposition layer made of silicon oxide or the like is used as the release layer. It is desirable to provide it. In addition, the formation order of the outer peripheral edge part 31 and the center part 32 of this catalyst layer 3 is not specifically limited. Moreover, as a coating method of each catalyst paste, well-known coating methods, such as screen printing, spray coating, die coating, knife coating, can be mentioned. 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.

  An example of the coating method of the first and second catalyst pastes will be described with reference to FIG. 5. First, an opening 91 a having the same size as the central portion 32 of the catalyst layer 3 is formed on the transfer substrate 81. The first mask 9a is placed (FIG. 5A). Then, the first catalyst paste is applied and dried on the transfer substrate 81 through the opening 91a of the first mask 9a to form the central portion 32 of the catalyst layer 3 (FIG. 5B). Next, the first mask 9a is removed, and a second mask 9b having the same size as the opening 91a of the first mask 9a, that is, the same size as the central portion 32 of the catalyst layer 3, is placed on the central portion 32. Then, the central portion 32 is masked (FIG. 5C). Then, the second catalyst paste is applied and dried on the transfer substrate 81 to form the outer peripheral edge 31 of the catalyst layer 3 (FIG. 5D). Then, the second mask 9b is removed, and the catalyst layer forming transfer sheet 8 is cut so that the width of the outer peripheral edge 31 becomes a desired value, thereby completing the catalyst layer forming transfer sheet 8 (FIG. 5E). ).

  Examples of the solvent used in each catalyst paste 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. 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.

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 (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 catalyst layer-electrolyte membrane laminated body 10 is formed by forming the catalyst layer 3 on both surfaces of the electrolyte membrane 2.

  Next, the reinforcing membrane 4 is attached to the catalyst layer-electrolyte membrane laminate 10 thus formed (FIG. 4C). An example of a method for manufacturing the reinforcing film 4 will be described. First, a sheet-like gas barrier layer 42 made of the above-described material is prepared. Then, the material of the adhesive layer 43 described above is melted, extruded onto the gas barrier layer 42 by a melt extrusion method, and the adhesive layer 43 is formed on the gas barrier layer 42 to produce the reinforcing film 4.

  The reinforcing membrane 4 produced as described above is joined to the catalyst layer-electrolyte membrane laminate 10 (FIG. 4C). This process will be described in detail with reference to FIG. FIG. 6 is a plan view showing a process of attaching the reinforcing membrane 4 to the catalyst layer-electrolyte membrane laminate 10. As shown in FIG. 6, the two reinforcing films 4 made of the above-described materials are overlapped, and the remaining three sides are left bonded to each other. As a result, the two reinforcing films 4 form a bag body in which an adhesive portion is formed in a U-shape and the left side is open (FIG. 6A). In addition, various well-known methods can be adopted as this bonding method, and for example, bonding can be performed by high-frequency welding, hot air welding, hot plate welding, impulse welding, iron welding, ultrasonic welding, or the like. .

  When the bag body is formed by the reinforcing film 4, an easy-removal region 44 is then formed at the center of each reinforcing film 4 constituting the bag body (FIG. 6B). The easy removal region 44 has substantially the same size as the central portion 32 of the catalyst layer 3. 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. Thus, the catalyst layer-electrolyte membrane laminated body 10 is inserted into the bag body in which the easy-removal region 44 is formed from the left side where it is not bonded, and moved to a predetermined position (FIG. 6C). This predetermined position refers to a position where a portion of the catalyst layer-electrolyte membrane laminate 10 excluding the outer peripheral edge 31 of the catalyst layer 3 faces the easy removal region 44.

  After moving the catalyst layer-electrolyte membrane laminate 10 to a predetermined position, the perforation at the outer periphery of the easy-removal region 44 is cut and the easy-removal regions 44 are removed from the respective reinforcing membranes 4. An opening 41 is formed at the center (FIG. 6D). As described above, when the easy removal regions 44 are removed from the respective reinforcing membranes 4 and the openings 41 are formed, the catalyst layers 3 of the catalyst layer-electrolyte membrane laminate 10 are removed from the respective openings 41 except for the outer peripheral edge 31. It will be exposed. In this state, the remaining portion of the reinforcing film 4 that has not been bonded is bonded by a known method, so that the reinforcing film 4 has the outer peripheral edge 31 of the catalyst layer 3 of the catalyst layer-electrolyte membrane laminate 10 or While adhering to the outer peripheral edge 21 of the electrolyte membrane 2, the reinforcing membranes 4 are also adhered to each other. The catalyst layer-electrolyte membrane laminate with a reinforcing membrane is completed through the above steps (FIGS. 6E and 4C).

  Returning to FIG. 4, the description of the method for producing the polymer electrolyte fuel cell 1 will be continued. A conductive porous substrate 5 is laminated by thermocompression bonding on the central portion 32 of the catalyst layer 3 exposed from the opening 41 of the catalyst layer-electrolyte membrane laminate described above, and the reinforcement membrane is attached. A membrane electrode assembly is completed (FIG. 4D). And the gasket 6 is arrange | positioned on the reinforcement film | membrane 4 so that the circumference | surroundings of the electrode E which consists of the catalyst layer 3 and the electroconductive porous base material 5 may be enclosed. Subsequently, the separator 7 is disposed on the conductive porous substrate 5 and the gasket 6 so that the gas flow path 71 faces the conductive porous substrate 5. Finally, the polymer electrode fuel cell 1 is completed by sandwiching the membrane electrode assembly with the separator 7 so that the conductive porous substrate 5 and the separator 7 are electrically connected (FIG. 4E). ).

  As described above, in the present embodiment, the catalyst is not included in the outer peripheral edge 31 of the catalyst layer 3 covered by the inner peripheral edge of the reinforcing film 4. For this reason, even if the generated water in which hydrogen peroxide is dissolved stays at the outer peripheral edge of the catalyst layer 3, the hydrogen peroxide is not radically decomposed, thereby preventing the reinforcing film from being peeled off by attacking the reinforcing film. can do.

  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, a fibrous material extending between the outer peripheral edge 31 of the catalyst layer 3 and the inner peripheral edge of the reinforcing membrane 4 may be further provided. Due to the anchor effect of the fibrous substance, the adhesion between the outer peripheral edge 31 of the catalyst layer 3 and the reinforcing film 4 can be improved. When the polymer electrolyte fuel cell 1 is manufactured, the fibrous material can be added to the second catalyst paste used for the outer peripheral edge 31 of the catalyst layer 3 or can be added to the adhesive layer 43. . As the material of the fibrous substance, metal, inorganic, organic polymer, etc. can be used. Specific examples include inorganic fibers and inorganic whiskers such as magnesium fibers, metal fibers such as stainless steel and titanium, vapor grown carbon fibers (VGCF (registered trademark)), carbon nanotubes, wire cups, wire walls, and other carbon fibers and glass fibers. , Other artificial polymers such as polyester and polyamide, animal and plant fibers such as cotton and silk, natural fibers such as wollastonite, polysaccharides such as cellulose and dextran, and regenerated fibers using polypeptides such as collagen, sericin and albumin And derivatives and complexes thereof. Among these, preferable fibrous materials include VGCF, glass fiber, and stainless metal fiber. These fibers can use 1 type (s) or 2 or more types. The fiber diameter is not limited, and the average may be 50 to 400 nm, preferably about 100 to 250 nm. The fiber length is not limited, and the average may be 5 to 500 μm, preferably about 10 to 200 μm. In addition, the fiber diameter and fiber length of the fiber can be measured by an image measured with a scanning electron microscope (SEM) or the like.

  Moreover, in the said embodiment, although the electroconductive porous base material 5 is formed on the catalyst layer exposed from the inside of the opening part 41 of the reinforcement film | membrane 4, as shown in FIG. 5 can be formed larger than the opening 41 of the reinforcing membrane 4, and the conductive porous substrate 5 can be installed so that the outer peripheral edge runs on the inner peripheral edge of the reinforcing membrane 4.

  Moreover, in the said embodiment, although the manufacturing method of once making the reinforcement membrane 4 into a bag body and inserting the catalyst layer-electrolyte membrane laminated body 10 is employ | adopted, it is not specifically limited to this. For example, the reinforcing film 4 in which the opening 41 is formed in advance on both surfaces of the catalyst layer-electrolyte membrane laminate 10 is disposed so that the adhesive layer 43 faces the catalyst layer-electrolyte membrane laminate 10, and the known adhesion is performed. The reinforcing film 4 may be adhered to both surfaces of the catalyst layer-electrolyte membrane laminate 10 by a method or the like to produce a catalyst layer-electrolyte membrane laminate with a reinforcing membrane.

  Moreover, in the said embodiment, although the reinforcement film | membrane 4 is comprised from two layers, the gas barrier layer 42 and the contact bonding layer 43, three or more layers may be sufficient. For example, a second adhesive layer may be further provided to form a three-layer structure including an adhesive layer 43, a gas barrier layer 42, and a second adhesive layer. The second adhesive layer is preferably configured to adhere to the gasket.

  In the above embodiment, the outer peripheral edge 31 of both the anode and cathode catalyst layers 3 does not contain a catalyst, but the outer peripheral edge 31 of the anode-side catalyst layer 3 may contain a catalyst.

  In the above embodiment, the electrolyte membrane 2, the catalyst layer 3, and the conductive porous substrate 5 constituting the solid polymer fuel cell 1 are all described as a rectangular shape in plan view, but the shape is particularly limited. Instead, for example, a circular shape in plan view can be used.

  The present invention will be described more specifically with reference to the following 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 (see FIG. 5). First, 2 g of platinum catalyst-supported carbon (platinum supported amount: 45.7 wt%, manufactured by Tanaka Kikinzoku Co., Ltd., TEC10E50E), 1 g of 1-butanol, 10 g of 3-butanol, 20 g of a fluororesin (5 wt% Nafion binder, manufactured by DuPont) and A first catalyst paste was prepared by adding 6 g of water and stirring and mixing them with a disperser. Moreover, 10 g of 1-butanol, 10 g of 3-butanol, 20 g of a fluororesin (5 wt% Nafion binder, manufactured by DuPont) and 6 g of water are added to 2 g of carbon particles (Furness Black (Vulcan xc72R, manufactured by Cabot)). A second catalyst paste was prepared by stirring and mixing in a disperser.

Next, a polyester film (X44, film thickness 25 μm) was prepared as a transfer substrate 81, and a first mask 9a having an opening 91a of 50 × 50 mm was placed on the transfer substrate 81. (FIG. 5 (a)). Then, the first catalyst paste is applied onto the transfer substrate 81 through the opening 91a of the first mask 9a and dried so that the platinum weight after drying the catalyst layer is 0.4 mg / cm ^2. Then, a central portion 32 of the catalyst layer 3 was produced (FIG. 5B).

  Subsequently, a second mask 9b having the same size as the central part 32 of the catalyst layer 3 formed by the first catalyst paste is placed so as to overlap the central part 32 of the catalyst layer 3 (FIG. 5C), The second catalyst paste was applied onto the transfer substrate 81 so as to have the same height after drying, and dried to form the outer peripheral edge 31 of the catalyst layer 3 (FIG. 5D). The catalyst layer forming transfer sheet 8 thus prepared was cut into a size of 60 × 60 mm so that the outer peripheral edge of the catalyst layer had a width of 5 mm, thereby completing the catalyst layer forming transfer sheet 8 (FIG. 5 ( e)).

  The cut catalyst layer forming transfer sheet 8 after the cutting was placed on both surfaces of the electrolyte membrane 2 so that the center of the catalyst layer 3 was directed to the electrolyte membrane 2 side. And the catalyst layer 3 was formed in both surfaces of the electrolyte membrane 2 by heat-pressing on conditions of 135 degreeC, 5.0 Mpa, and 150 second, and the catalyst layer-electrolyte membrane laminated body 10 was produced. The thickness of the catalyst layer 3 is 20 μm for both the outer peripheral edge portion 31 and the central portion 32.

Subsequently, the reinforcing film 4 was produced. As the gas barrier layer 42 of the reinforcing film 4, biaxially stretched polyethylene naphthalate (manufactured by Teijin Ltd., Teonex, film thickness: 12 μm) was used. On the gas gas barrier layer 42, by a melt extrusion method, an unsaturated carboxylic acid graft-modified polypropylene extruded at a thickness of 30 [mu] m, to form an adhesive layer 43. The reinforcing film 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. Then, the reinforcing membrane 4 is disposed on both surfaces of the catalyst layer-electrolyte membrane laminate 10 so that the opening 41 overlaps the central portion 32 of the catalyst layer 3, and is hot pressed under conditions of 130 ° C., 1.0 MPa, 30 seconds. Thus, the reinforcing membrane 4 was welded to the catalyst layer-electrolyte membrane laminate 10 to prepare a catalyst layer-electrolyte membrane laminate with a reinforcing membrane.

  Subsequently, carbon paper (TGP-H-090, manufactured by Toray Industries, Inc., cut into a size of 49 × 49 mm as the conductive porous substrate 5 on the catalyst layer 3 exposed from the opening 41. A membrane electrode assembly with a reinforcing membrane was formed.

(Example 2)
As Example 2, the electrolyte with the reinforcing film is the same material, dimensions, and manufacturing method as in Example 1 except that the material of the reinforcing film 4 is different and the size of the conductive porous substrate 5 is different. A membrane-electrode assembly was produced.

  In addition, the material of the reinforcing film 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, unsaturated carboxylic acid graft-modified polyethylene was extruded at a thickness of 30 μm by melt extrusion to form an adhesive layer 43.

Also, as the conductive porous substrate 5, carbon paper (TGP-H-090, thickness: 280 μm) cut to a size of 50 × 50 mm is laminated, and a membrane electrode assembly with a reinforcing film is laminated. Formed.
(Example 3)
Except that the size of the electrolyte membrane 2 is different, that the second catalyst paste used for the outer peripheral edge 31 of the catalyst layer 3 contains carbon fibers, and that the material used for the reinforcing membrane 4 is the same as that of the second embodiment. Produced a membrane electrode assembly with a reinforcing membrane by the same material, dimensions and manufacturing method as in Example 1 described above. The second catalyst paste is 1.5 g of carbon particles (furnace black (Vulcan xc72R, manufactured by Cabot)), 0.5 g of VGCF (standard product) (manufactured by Showa Denko KK), 10 g of 1-butanol, It was prepared by adding 10 g of 3-butanol, 20 g of a fluororesin (5 wt% Nafion binder, manufactured by DuPont) and 6 g of water, and stirring and mixing them with a disperser. The size of the electrolyte membrane 2 was 60 mm × 60 mm.

Example 4
A membrane electrode assembly with a reinforcing membrane was produced with the same material, dimensions and production method as in Example 1 except that the second catalyst paste used for the outer peripheral edge 31 of the catalyst layer 3 contains metal fibers. . The second catalyst paste is 1.5 g of carbon particles (furness black (Vulcan xc72R, manufactured by Cabot)), 0.5 g of X-SMF300UE-EP (manufactured by JFE Techno-Research Corporation), 10 g of 1-butanol. 10 g of 3-butanol, 20 g of a fluororesin (5 wt% Nafion binder, manufactured by DuPont) and 6 g of water were added, and these were stirred and mixed in a disperser.

(Example 5)
Except for the point that the second catalyst paste used for the outer peripheral edge 31 of the catalyst layer 3 contains glass fiber and the same material as that of Example 2 was used as the material of the reinforcing film 4, Example 1 described above and A membrane electrode assembly with a reinforcing membrane was produced using the same material, dimensions and manufacturing method. The second catalyst paste is composed of 1.5 g of carbon particles (furness black (Vulcan xc72R, manufactured by Cabot)) and quartz wool (super fine (fiber thickness: 0.5-3 μm), manufactured by Daiko Seisakusho Co., Ltd.). It was prepared by adding 0.5 g, 10 g of 1-butanol, 10 g of 3-butanol, 20 g of a fluororesin (5 wt% Nafion binder, manufactured by DuPont) and 6 g of water, and stirring and mixing them with a disperser.

(Evaluation method)
About the membrane electrode assembly with a reinforcement film of Examples 1-5, the gasket 6 and the separator 7 were installed, the polymer electrolyte fuel cell was produced, respectively, and the load fluctuation cycle test was implemented, and the result is shown in Table 1. It was. 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 power was generated at a current density of 0.01 A / cm ^{2 for} 1 minute was repeated. As a result of the load fluctuation cycle test, the voltage did not decrease even after 1000 hours of the fuel cells of Examples 1 and 2 and 1500 hours of the fuel cells of Examples 3 to 5. As a result of observation of the electrolyte membrane after the load change cycle test, breakage of the electrolyte membrane in all examples were Tsu or such was observed.

DESCRIPTION OF SYMBOLS 1 Solid polymer fuel cell 2 Ion conductive polymer electrolyte membrane 3 Catalyst layer 31 Outer peripheral edge 4 Reinforcement membrane 41 Opening 5 Conductive porous substrate 6 Gasket 7 Separator 10 Catalyst layer-electrolyte membrane laminate 20 Membrane electrode Zygote

Claims (8)

An ion conductive polymer electrolyte membrane;
A catalyst layer formed on both surfaces of the electrolyte membrane and containing carbon particles, an ion conductive polymer electrolyte, and a catalyst;
It has an opening in the center, and was adhered to both surfaces of the catalyst layer-electrolyte membrane laminate composed of the electrolyte membrane and the catalyst layer so that the inner peripheral edge was adhered onto the outer peripheral edge of the catalyst layer. A reinforcing membrane,
The catalyst layer is a catalyst layer-electrolyte membrane laminate with a reinforcing film that does not contain a catalyst in the outer peripheral edge portion. The said catalyst layer is formed on the said electrolyte membrane except the outer periphery part of the said electrolyte membrane, The said reinforcement film | membrane is adhere | attached also on the outer periphery part of the said electrolyte membrane. A catalyst layer-electrolyte membrane laminate with a reinforcing membrane. The catalyst with a reinforcing membrane according to claim 1 or 2, wherein the reinforcing membrane is formed to be slightly larger than the electrolyte membrane, and the outer peripheral edges of the reinforcing membrane are bonded to each other outside the electrolyte membrane. Layer-electrolyte membrane laminate.   The catalyst layer-electrolyte membrane laminate with a reinforcing film according to any one of claims 1 to 3, further comprising a fibrous substance extending between an outer peripheral edge of the catalyst layer and an inner peripheral edge of the reinforcing membrane.   The catalyst layer-electrolyte with a reinforcing film according to any one of claims 1 to 4, wherein the reinforcing film has an adhesive layer that adheres to the catalyst layer, and a gas barrier layer that prevents permeation of fuel gas and oxidant gas. Membrane laminate. A catalyst layer-electrolyte membrane laminate with a reinforcing membrane according to any one of claims 1 to 5,
A conductive porous substrate formed on each of the catalyst layers;
A membrane electrode assembly with a reinforcing membrane, comprising:   The membrane electrode assembly with a reinforcing membrane according to claim 6, wherein the conductive porous substrate is formed on a catalyst layer exposed from an opening of each of the reinforcing membranes. A membrane electrode assembly with a reinforcing membrane according to claim 6 or 7,
A gasket installed on each reinforcing membrane;
A separator installed so as to sandwich the membrane electrode assembly with a reinforcing membrane provided with the gasket from both sides;
A solid polymer fuel cell comprising:

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