JP2018085169A - Electrolyte membrane-electrode assembly and fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent aging deterioration of resin forming a sealing part of an electrolyte membrane-electrode assembly, thereby providing the electrolyte membrane-electrode assembly which is free from reaction gas leakage and excellent in durability.SOLUTION: An electrolyte membrane-electrode assembly 10 comprises: an electrolyte membrane 11; an anode catalyst layer 12 and a cathode catalyst layer 13 each of which is formed substantially at the center on a principal surface of the electrolyte membrane 11; a gas diffusion layer 14 which is arranged outside the anode catalyst layer 12 and the cathode catalyst layer 13; and resin 15 which bonds together the electrolyte membrane 11, the anode catalyst layer 12, the cathode catalyst layer 13, and the gas diffusion layer 14. An exposed portion 11a of the electrolyte membrane 11, which is not covered with the anode catalyst layer 12, the cathode catalyst layer 13, or the gas diffusion layer 14 and which protrudes in the radially outer direction, contains substantially no hydrogen ions. As a result, the resin 15 is less likely to be deteriorated from aging, thereby making it possible to prevent reaction gas leakage from the electrolyte membrane-electrode assembly 10.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an electrolyte membrane-electrode assembly and a fuel cell for a polymer electrolyte fuel cell used for a home cogeneration system, a power source for an electric vehicle, a portable power source and the like.

  A solid polymer fuel cell using an electrolyte membrane-electrode assembly is known as a fuel cell that generates electric power by an electrochemical reaction between a fuel gas and an oxidant gas.

  In this electrolyte membrane-electrode assembly, a catalyst layer and an electrode base material are arranged on both main surfaces of an electrolyte membrane made of a polymer, and the electrolyte membrane, the catalyst layer, and the electrode base material are joined using a resin such as polypropylene. It consists of

  The polymer electrolyte fuel cell includes an electrolyte membrane-electrode assembly having the above structure and a pair of separators provided with gas supply grooves for supplying a fuel gas and an oxidant gas as reaction gases on the outside thereof. (For example, refer to Patent Document 1).

  FIG. 5 (a) is a cross-sectional view showing a schematic configuration of a conventional electrolyte membrane-electrode assembly, and FIG. 5 (b) is a cross-sectional view showing a schematic configuration of a unit cell incorporated in a conventional polymer electrolyte fuel cell. FIG.

  As shown in FIG. 5A, the electrolyte membrane-electrode assembly 50 includes a strongly acidic electrolyte membrane 51 containing hydrogen ions, an anode 55 composed of an anode catalyst layer 52 and an electrode substrate 54, and a cathode catalyst layer 53. And an electrode substrate 54, an electrolyte membrane 51, an anode catalyst layer 52, a cathode catalyst layer 53, and a resin 57 that joins the electrode substrate 54.

  Here, the electrolyte membrane 51 has an exposed portion 51 a that protrudes outward in the radial direction without being covered with the anode catalyst layer 52, the cathode catalyst layer 53, and the electrode base material 54.

  Then, the resin 57 disposed so as to surround the anode catalyst layer 52, the cathode catalyst layer 53, and the electrode base material 54 in the exposed portion 51a attaches the electrolyte membrane 51, the anode catalyst layer 52, the cathode catalyst layer 53, and the electrode base material 54 to each other. The sealing part 58 is formed in the edge part of the electrolyte membrane electrode assembly 50 by joining, and the leakage of the reaction gas from the electrolyte membrane electrode assembly 50 is prevented.

  Further, as shown in FIG. 5B, the unit cell 59 incorporated in the polymer electrolyte fuel cell includes a fuel gas supply for supplying fuel gas to the electrolyte membrane-electrode assembly 50 and the anode 55 having the above-described configuration. An anode separator 510 provided with a groove and a cathode separator 511 provided with an oxidant gas supply groove for supplying an oxidant gas to the cathode 56 are provided.

  The polymer electrolyte fuel cell includes a fuel cell stack in which a plurality of unit cells 59 having the above configuration are stacked.

  In the polymer electrolyte fuel cell having the above configuration, when the fuel gas and the oxidant gas as the reaction gas are supplied to the fuel gas supply groove of the anode separator 510 and the oxidant gas supply groove of the cathode separator 511 of the unit cell 59, In the anode 55 and the cathode 56 of the battery 59, the electrochemical reaction shown in the following formulas (1) and (2) proceeds to generate an electromotive force.

_{^{Anode: 2H 2 → 4H + + 4e}} - ···· formula (1)
Cathode: O ₂ + 4H ⁺ + 4e ⁻ → 2H ₂ O (2)
In the anode 55, as shown in the formula (1), hydrogen in the supplied fuel gas is dissociated into hydrogen ions and electrons. At that time, hydrogen ions pass through the electrolyte membrane 51 and electrons move to the cathode 56 through the external circuit. On the other hand, at the cathode 56, as shown in Formula (2), oxygen in the supplied oxidant gas reacts with the hydrogen ions and electrons described above to generate water. At this time, electrons passing through the external circuit become current and can be supplied with electric power.

  In addition, the water produced | generated by reaction of Formula (1) and Formula (2) is discharged | emitted outside the fuel cell with the reactive gas which was not consumed by the fuel cell.

  In this fuel cell, the electrochemical reaction is continued by continuously supplying the reaction gas, and the battery voltage can be maintained and stable power generation can be continued. Therefore, the reaction gas supplied to the anode 55 and the cathode 56 is changed to the electrolyte membrane. -Sufficient durability is required for the electrolyte membrane-electrode assembly 50 so as not to leak outside the electrode assembly 50.

JP 2005-158690 A

  However, in the above-described conventional configuration, the resin that forms the sealing portion of the electrolyte membrane-electrode assembly is in an acidic atmosphere by directly contacting the electrolyte membrane that contains hydrogen ions and exhibits strong acidity in the exposed portion of the electrolyte membrane. As a result of exposure, there was a problem that the sealing portion of the electrolyte membrane-electrode assembly was deteriorated with age and cracks and breakage occurred, and the reaction gas leaked from the electrolyte membrane-electrode assembly.

  In addition, in the fuel cell using the electrolyte membrane-electrode assembly having such a conventional configuration, since the reaction gas leaks from the electrolyte membrane-electrode assembly, the battery voltage decreases and stable power generation is continued. Had the problem of not being able to.

  The present invention solves the above-mentioned conventional problems, and provides a means for preventing deterioration over time of the resin forming the sealing portion of the electrolyte membrane-electrode assembly, and is durable with no leakage of reaction gas. An object is to provide an excellent electrolyte membrane-electrode assembly.

  The present invention also provides a fuel cell having excellent durability that can maintain a battery voltage over a long period of time and continue stable power generation using such an electrolyte membrane-electrode assembly. One of the purposes.

  In order to solve the above-described conventional problems, an electrolyte membrane-electrode assembly according to the present invention includes an electrolyte membrane, a catalyst layer having a smaller area than the electrolyte membrane and disposed at substantially the center of both main surfaces of the electrolyte membrane, and a catalyst layer A resin that joins the catalyst layer and the gas diffusion layer to a gas diffusion layer disposed outside the electrode, an exposed portion that protrudes radially outward without being covered with the catalyst layer and the gas diffusion layer of the electrolyte membrane, An electrolyte membrane-electrode assembly having a resin layer and a resin disposed so as to surround the gas diffusion layer, wherein the exposed portion of the electrolyte membrane does not substantially contain hydrogen ions.

  Accordingly, since the exposed portion of the electrolyte membrane does not substantially contain hydrogen ions, the resin forming the sealing portion of the electrolyte membrane-electrode assembly is not exposed to an acidic atmosphere and does not deteriorate over time. Therefore, leakage of the reaction gas from the electrolyte membrane-electrode assembly can be prevented.

  The fuel cell of the present invention includes the electrolyte membrane-electrode assembly according to the present invention and a pair of separators that sandwich the electrolyte membrane-electrode assembly from both sides.

  Accordingly, leakage of the reaction gas from the electrolyte membrane-electrode assembly can be prevented, so that the fuel cell can maintain the battery voltage over a long period of time and continue stable power generation.

  Since the electrolyte membrane-electrode assembly of the present invention can prevent deterioration over time of the resin forming the sealing portion, it is possible to prevent leakage of reaction gas from the electrolyte membrane-electrode assembly.

  In addition, since the fuel cell of the present invention uses an electrolyte membrane-electrode assembly excellent in durability with no leakage of reaction gas, the battery voltage is maintained over a long period of time and stable power generation is continued. Can do.

(A) is an external appearance perspective view which shows the electrolyte membrane-electrode assembly in Embodiment 1 of this invention, (b) is AA of (a) of the electrolyte membrane-electrode assembly in Embodiment 1 of this invention. Line cross section The flowchart which shows the manufacturing method of the electrolyte membrane-electrode assembly in Embodiment 2 of this invention. Process drawing which shows typically the mode of each process in the manufacturing method of the electrolyte membrane-electrode assembly in Embodiment 2 of this invention. (A) is sectional drawing which shows schematic structure of the fuel cell in Embodiment 3 of this invention, (b) is sectional drawing which shows schematic structure of the unit cell integrated in the fuel cell in Embodiment 3 of this invention. (A) is sectional drawing which shows schematic structure of the conventional electrolyte membrane electrode assembly, (b) is sectional drawing which shows schematic structure of the single cell integrated in the conventional fuel cell.

  The first invention includes an electrolyte membrane, a catalyst layer having an area smaller than that of the electrolyte membrane and disposed substantially at the center of both main surfaces of the electrolyte membrane, a gas diffusion layer disposed outside the catalyst layer, and a catalyst for the electrolyte membrane A resin that is bonded to the catalyst layer and the gas diffusion layer, and that is disposed so as to surround the gas diffusion layer, the exposed portion protruding in the radially outward direction without being covered with the gas layer and the gas diffusion layer; The exposed portion of the electrolyte membrane is substantially free of hydrogen ions.

  With this configuration, since the exposed portion of the electrolyte membrane does not substantially contain hydrogen ions, the resin constituting the sealing portion of the electrolyte membrane-electrode assembly is not exposed to an acidic atmosphere and deteriorates over time. Therefore, it is possible to realize an electrolyte membrane-electrode assembly with excellent durability and no leakage of reaction gas.

  A second invention is a fuel cell having the electrolyte membrane-electrode assembly according to the first invention and a pair of separators sandwiching the electrolyte membrane-electrode assembly from both sides.

  With this configuration, leakage of the reaction gas from the electrolyte membrane-electrode assembly can be prevented, so that a fuel cell excellent in durability for maintaining battery voltage over a long period and continuing stable power generation is realized. be able to.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments.

(Embodiment 1)
FIG. 1A is an external perspective view showing an electrolyte membrane-electrode assembly in Embodiment 1 of the present invention, and FIG. 1B is an electrolyte membrane-electrode in Embodiment 1 of the present invention. It is an AA line sectional view of (a) of a joined object.

  As shown in FIG. 1, an electrolyte membrane-electrode assembly 10 according to the present embodiment includes an electrolyte membrane 11, an anode catalyst layer 12 disposed (formed) at substantially the center of one main surface of the electrolyte membrane 11, The cathode catalyst layer 13 disposed (formed) substantially at the center of the other main surface of the electrolyte membrane 11, the anode catalyst layer 12, the gas diffusion layer 14 disposed outside the cathode catalyst layer 13, and the anode catalyst layer 12, respectively. And a resin 15 disposed so as to surround the cathode catalyst layer 13 and the gas diffusion layer 14.

  The electrolyte membrane-electrode assembly 10 of the present embodiment will be specifically described below with respect to the material, structure, and action of its constituent elements.

  The electrolyte membrane 11 is made of a perfluoroalkylsulfonic acid-based polymer partially containing hydrogen ions, and has a larger area than the anode catalyst layer 12, the cathode catalyst layer 13, and the gas diffusion layer 14. An exposed portion 11 a that is not covered by the catalyst layer 13 and the gas diffusion layer 14 and protrudes outward in the radial direction of the anode catalyst layer 12, the cathode catalyst layer 13, and the gas diffusion layer 14 is provided.

The exposed portion 11a is formed by substituting a hydrogen ion of a sulfonic acid group (—SO ₃ H) contained in the polymer with a sodium ion to form a sodium sulfonate group (—SO ₃ Na), and substantially contains a hydrogen ion. Not in.

On the other hand, portions other than the exposed portion 11a of the electrolyte membrane 11 (portions covered with the anode catalyst layer 12, the cathode catalyst layer 13, and the gas diffusion layer 14) are hydrogen of a sulfonic acid group (—SO ₃ H) contained in the polymer. Without replacing the ions, the sulfonic acid group (—SO ₃ H) is retained, and hydrogen ions are contained, and the hydrogen ions generated by the electrochemical reaction in the anode catalyst layer 12 are transported to the cathode catalyst layer 13. Yes.

  The anode catalyst layer 12 and the cathode catalyst layer 13 have an area smaller than that of the electrolyte membrane 11, and are configured to include a catalyst powder made of carbon particles carrying platinum or a platinum alloy and an ionomer that transports hydrogen ions. It fulfills the function of promoting the electrochemical reaction of the reaction gas supplied to the body 10.

  The gas diffusion layer 14 has substantially the same area as the anode catalyst layer 12 and the cathode catalyst layer 13, and is composed of a conductive material mainly composed of carbon fiber having both gas permeability and electronic conductivity. The reaction gas supplied to the electrolyte membrane-electrode assembly 10 is sent to the anode catalyst layer 12 and the cathode catalyst layer 13, and the water generated in the cathode catalyst layer 13 is drained to the outside of the electrolyte membrane-electrode assembly 10. Plays a function.

  The resin 15 is composed of a thermosetting resin whose main component is an epoxy resin, and the electrolyte membrane 11 is joined to the anode catalyst layer 12, the cathode catalyst layer 13, and the gas diffusion layer 14. The sealing portion 16 is formed at the end portion of 10 to prevent the leakage of the reaction gas from the electrolyte membrane-electrode assembly 10.

As described above, in the present embodiment, the electrolyte membrane 11 constituting the electrolyte membrane-electrode assembly 10 is not covered with the anode catalyst layer 12, the cathode catalyst layer 13, and the gas diffusion layer 14, and is radially outward. Since the protruded exposed portion 11a is substantially free of hydrogen ions, the resin 15 forming the sealing portion 16 of the electrolyte membrane-electrode assembly 10 is not exposed to an acidic atmosphere, and is aged. Therefore, the electrolyte membrane-electrode assembly 10 having excellent durability with no leakage of reaction gas can be realized.

(Embodiment 2)
FIG. 2 is a flowchart showing a method for manufacturing the electrolyte membrane-electrode assembly in the second embodiment of the present invention. FIG. 3 is a process diagram schematically showing each step in the method for manufacturing an electrolyte membrane-electrode assembly in the second embodiment of the present invention.

  As shown in FIG. 2, the manufacturing method of the electrolyte membrane-electrode assembly 10 according to the present embodiment is an anode catalyst composition preparation step in which anode catalyst powder is kneaded with an ionomer and a dispersion medium to obtain an anode catalyst composition 31 ( S11), a cathode catalyst composition preparation step (S12) in which the cathode catalyst powder is kneaded with an ionomer and a dispersion medium to obtain the cathode catalyst composition 32, and a solution in which a water repellent material is dispersed in the porous body 33 is applied, A gas diffusion layer preparation step (S13) to obtain a gas diffusion layer 14 by drying, and an anode catalyst composition 31 is applied to the central portion of one surface of the electrolyte membrane 11 containing hydrogen ions, and dispersed from the anode catalyst composition 31 The anode catalyst layer forming step (S14) for forming the anode catalyst layer 12 by removing the medium, and the central portion of the other surface of the electrolyte membrane 11 containing hydrogen ions In the cathode catalyst layer forming step (S15) for forming the cathode catalyst layer 13 by applying the cathode catalyst composition 32 and removing the dispersion medium from the cathode catalyst composition 32, and in the electrolyte membrane 11 containing hydrogen ions, An exposed portion forming step (S16) of forming an exposed portion 11a substantially free of hydrogen ions in the electrolyte membrane 11 by neutralizing the hydrogen ions in a portion where the anode catalyst layer 12 and the cathode catalyst layer 13 are not formed; In addition, a sealing portion forming step (S17) is included in which the electrolyte membrane 11, the anode catalyst layer 12, the cathode catalyst layer 13, and the gas diffusion layer 14 are joined using the resin 15 to form the sealing portion 16.

  Hereinafter, the manufacturing method of the above-described electrolyte membrane-electrode assembly 10 will be described in further detail with reference to FIG. 2 and FIG. In FIG. 3, the same constituent elements as those in FIG.

[Anode catalyst composition preparation step (S11)]
In this step, the anode catalyst composition 31 is obtained from the anode catalyst powder, the ionomer, and the dispersion medium. Specifically, the anode catalyst powder, the ionomer and the dispersion medium are collected in a container, and the anode catalyst powder is kneaded with the ionomer and the dispersion medium under predetermined conditions to produce an anode catalyst composition 31 (FIG. 3). (A)).

[Cathode Catalyst Composition Preparation Step (S12)]
In this step, the cathode catalyst composition 32 is obtained from the cathode catalyst powder, the ionomer, and the dispersion medium. Specifically, the cathode catalyst powder, the ionomer and the dispersion medium are collected in a container, and the cathode catalyst powder is kneaded with the ionomer and the dispersion medium under predetermined conditions to produce the cathode catalyst composition 32 (FIG. 3). (B)).

[Gas Diffusion Layer Fabrication Step (S13)]
In this step, the water repellent layer 34 is formed on the surface of the conductive porous body 33 to obtain the gas diffusion layer 14. Specifically, after applying a solution in which a fluorine-based water repellent material is dispersed on one surface of the porous body 33 containing carbon fibers, the water-repellent layer is applied on one surface of the porous body 33 containing carbon fibers by drying. 34 is formed to produce the gas diffusion layer 14 (FIG. 3C).

[Anode catalyst layer forming step (S14)]
In this step, the anode catalyst composition 31 prepared in the anode catalyst composition preparation step (S11) is applied to the central portion of one surface of the electrolyte membrane 11 containing hydrogen ions, and the dispersion medium is removed from the anode catalyst composition 31. Thus, the anode catalyst layer 12 is formed.

  Specifically, the electrolyte membrane 11 containing hydrogen ions is fixed, and the anode catalyst composition 31 is applied to one surface thereof with the edges of the four sides masked by a screen printing method, and then the anode catalyst composition By heating 31 under predetermined conditions, the dispersion medium is removed from the anode catalyst composition 31, and the anode catalyst layer 12 is formed at the center of one surface of the electrolyte membrane 11 containing hydrogen ions (FIG. 3). (D)).

[Cathode catalyst layer forming step (S15)]
In this step, the cathode catalyst composition 32 prepared in the cathode catalyst composition preparation step (S12) is applied to the center of the other surface of the electrolyte membrane 11 containing hydrogen ions, and the dispersion medium is removed from the cathode catalyst composition 32. Thus, the cathode catalyst layer 13 is formed.

  Specifically, the electrolyte membrane 11 in which the anode catalyst layer 12 is formed at the center of one surface is fixed so that the surface opposite to the surface on which the anode catalyst layer 12 is formed is on the upper side. The cathode catalyst composition 32 is applied to the other surface of the electrolyte membrane 11 containing ions by screen printing in a state where the edges of the four sides are masked.

  Thereafter, the cathode catalyst composition 32 is heated under predetermined conditions to remove the dispersion medium from the cathode catalyst composition 32, and the cathode catalyst layer 13 is formed at the center of the other surface of the electrolyte membrane 11 containing hydrogen ions. Is formed ((e) of FIG. 3).

[Exposed Portion Forming Step (S16)]
In this step, hydrogen ions in a portion of the electrolyte membrane 11 where the anode catalyst layer 12 and the cathode catalyst layer 13 are not formed are neutralized with the treatment liquid 35 so that the electrolyte membrane 11 does not substantially contain hydrogen ions. The exposed portion 11a is formed.

  Specifically, by immersing the ends of the four sides of the electrolyte membrane 11 containing hydrogen ions where the anode catalyst layer 12 and the cathode catalyst layer 13 are not formed in a container storing the treatment liquid 35 under predetermined conditions, After neutralizing the hydrogen ions in the portion of the electrolyte membrane 11 where the anode catalyst layer 12 and the cathode catalyst layer 13 are not formed, the electrolyte membrane 11 is taken out of the container, and the electrolyte membrane 11 is exposed substantially free of hydrogen ions. The part 11a is formed (FIG. 3F).

[Sealing part forming step (S17)]
In this step, a resin 15 is applied to the exposed portion 11a of the electrolyte membrane 11, the anode catalyst layer 12, the cathode catalyst layer 13, and the gas diffusion layer 14, and the electrolyte membrane 11, the anode catalyst layer 12, the cathode catalyst layer 13, and the gas diffusion are applied. The sealing portion 16 is formed by bonding the layer 14.

  Specifically, after the gas diffusion layer 14 produced in the gas diffusion layer forming step (S13) is disposed outside the anode catalyst layer 12 and the cathode catalyst layer 13 of the electrolyte membrane 11, the exposed portion 11a and the end surface of the electrolyte membrane 11 are disposed. After the resin 15 is applied to the end surfaces of the anode catalyst layer 12 and the cathode catalyst layer 13 and the end surface of the gas diffusion layer 14, the resin 15 is cured to form the sealing portion 16, and the electrolyte membrane-electrode assembly 10 is formed. It is manufactured ((g) in FIG. 3).

  Hereinafter, although the manufacturing method of the electrolyte membrane-electrode assembly 10 according to the present embodiment will be described in more detail based on specific examples, the present invention is based on the contents of specific raw materials and the like used below. It is not necessarily limited.

Example 1
In this embodiment, after the anode catalyst layer 12 and the cathode catalyst layer 13 are formed at the center of both surfaces of the electrolyte membrane 11, a hydrogen ion is substantially applied to the electrolyte membrane 11 using a treatment liquid 35 made of an aqueous solution containing a metal salt. An electrolyte membrane-electrode assembly 10 was manufactured by forming an exposed portion 11a that does not contain the material.

(1) Anode catalyst composition preparation process Afford 10% Nafion dispersion (Sigma) as an ionomer with respect to 100 parts by weight of anode catalyst powder (product number: TEC66E50 manufactured by Tanaka Kikinzoku Co., Ltd.) consisting of carbon powder supporting platinum and ruthenium. Aldrich, product number: 527114) 300 parts by weight, 150 parts by weight of pure water and 300 parts by weight of ethanol as a dispersion medium were collected in a container, and a disperser (product name: RS-05W, manufactured by Seiwa Giken Co., Ltd.) Using an ultrasonic homogenizer (Nippon Seiki Seisakusho, product name: US-150E), the mixture was kneaded at room temperature for 2 hours to prepare a catalyst composition (hereinafter referred to as catalyst composition a).

(2) Cathode catalyst composition preparation step Cathode catalyst powder made of carbon powder carrying platinum (Tanaka Kikinzoku Co., Ltd., product number: TEC10E50E) 100 parts by weight of Nafion 10% dispersion (Sigma Aldrich Co.) as an ionomer (Product number: 527114) 300 parts by weight, 150 parts by weight of pure water and 300 parts by weight of ethanol as a dispersion medium are collected in a container, and a disperser (manufactured by Seiwa Giken, product name: RS-05W) and ultrasonic waves are collected. Using a homogenizer (Nippon Seiki Seisakusho, product name: US-150E), the mixture was kneaded at room temperature for 2 hours to prepare a catalyst composition (hereinafter referred to as catalyst composition b).

(3) Gas diffusion layer preparation process Carbon paper (product name: TGP-H-120, manufactured by Toray Industries, Inc.) is prepared as a porous body 33 containing carbon fibers, and polytetratetrahydrofuran is used as a water repellent material on one surface thereof. After applying a mixture in which 500 parts by weight of pure water was mixed with 100 parts by weight of a dispersion of fluoroethylene (manufactured by Daikin Industries, Ltd., product name: C-1), the mixture was heated and dried at 350 ° C. for 2 hours. A gas diffusion layer having a water repellent layer 34 (hereinafter referred to as a gas diffusion layer c) was produced.

(4) Anode catalyst layer forming step An electrolyte membrane (manufactured by DuPont, trade name: Nafion 112) cut into a square with a side length of 100 mm is prepared, and the catalyst composition a is screened on one surface thereof. Using a printing machine (product name: CP-320, manufactured by Neurong Seimitsu Kogyo Co., Ltd.), coating was performed by a screen printing method.

  A screen mask is used for printing. The catalyst composition a is formed in the center of the Nafion 112 so that the shape of the catalyst composition a to be printed is a square having a length of 80 mm, and on the four sides of the Nafion 112. It applied so that the edge part of width 10mm which the composition a was not apply | coated might remain.

  Subsequently, the Nafion 112 coated with the catalyst composition a is left in a thermostat (manufactured by Yamato Scientific Co., Ltd., model number: CKM300) for 1 hour by heating and drying the dispersion medium from the catalyst composition a. After the removal, the anode catalyst layer 12 was formed at the center of one surface of the Nafion 112 by being left at room temperature for 1 hour.

(5) Cathode catalyst layer forming step The catalyst composition b is applied to the other surface of the Nafion 112 having the anode catalyst layer 12 formed at the center of one surface by the above-described anode catalyst layer forming step. Using Long Seimitsu Kogyo Co., Ltd., product name: CP-320, it was applied by screen printing.

  A screen mask is used for printing. The catalyst composition b is formed in the center of the Nafion 112 so that the shape of the catalyst composition b to be printed is a square having a side length of 80 mm, and on the four sides of the Nafion 112. It applied so that the edge part of the width 10mm in which the composition b was not apply | coated might remain.

  Subsequently, the Nafion 112 coated with the catalyst composition b is left in a thermostat (manufactured by Yamato Scientific Co., Ltd., model number: CKM300) for 1 hour by heating and drying the dispersion medium from the catalyst composition b. After the removal, the cathode catalyst layer 13 was formed at the center of the other surface of the Nafion 112 by being left at room temperature for 1 hour.

(6) Exposed portion forming step 500 parts by weight of pure water is collected in a container with respect to 100 parts by weight of sodium chloride, and 10 parts at 25 ° C. using a stirrer (product name: MAGMIXER) The mixture was stirred for a minute to prepare a treatment liquid 35 consisting of an aqueous sodium chloride solution.

  Next, the anode catalyst layer 12 and the cathode catalyst layer 13 are formed in the Nafion 112 in which the anode catalyst layer 12 and the cathode catalyst layer 13 are formed at the center by the anode catalyst layer forming step and the cathode catalyst layer forming step described above. The ends of the four sides that are not used are immersed for 30 minutes in the above-mentioned container containing the sodium chloride aqueous solution to replace the hydrogen ions contained in the ends of the four sides of the Nafion 112 with sodium ions. After neutralization, the sample was taken out from the container, and exposed portions 11a substantially free of hydrogen ions were formed at the ends of the four sides of the Nafion 112.

  The amount of the sodium chloride aqueous solution was set until the end portion of the Nafion 112 was soaked so that only the end portion of the Nafion 112 was immersed in the sodium chloride aqueous solution.

(7) Sealing portion forming step The gas diffusion layer c produced by the above-described gas diffusion layer forming step is formed on one side so as to have an area of almost the same size as the anode catalyst layer 12 and the cathode catalyst layer 13 formed on the Nafion 112. A square having a length of 80 mm was cut out and disposed on each surface of the anode catalyst layer 12 and the cathode catalyst layer 13 so that the water repellent layer 34 was in contact with the anode catalyst layer 12 and the cathode catalyst layer 13.

  Next, an epoxy resin (manufactured by Konishi Co., Ltd., trade name: Bondquick 5) is prepared as the resin 15, and exposed portions and end surfaces of the Nafion 112, end surfaces of the anode catalyst layer 12 and the cathode catalyst layer 13, and a gas diffusion layer. After coating so as to cover the end face of c, it was left to heat and cure in a 50 ° C. thermostat (manufactured by Yamato Scientific Co., Ltd., model number: CKM300) for 1 hour, and Nafion 112, anode catalyst layer 12 and cathode catalyst layer 13 and the gas diffusion layer c were joined to form a sealing portion 16, and an electrolyte membrane-electrode assembly (hereinafter referred to as an electrolyte membrane-electrode assembly A) was produced.

(Example 2)
In this embodiment, after the anode catalyst layer 12 and the cathode catalyst layer 13 are formed at the center of both surfaces of the electrolyte membrane 11, the electrolyte membrane 11 is substantially subjected to hydrogenation using a treatment solution 35 made of an aqueous solution containing a nonmetallic salt. The electrolyte membrane-electrode assembly 10 was manufactured by forming the exposed portion 11a not containing ions.

The above-described steps (1) to (5) of Example 1 were performed, and the anode catalyst layer 12 and the cathode catalyst layer 13 having a side length of 80 mm were formed at the center of both surfaces of the Nafion 112. Subsequently, with respect to 100 parts by weight of ammonium chloride, 500 parts by weight of pure water was collected in a container and stirred for 10 minutes at 25 ° C. using a stirrer (manufactured by Yamato Scientific Co., Ltd., product name: Magmixer). A treatment liquid 35 made of an aqueous ammonium chloride solution was prepared.

  Subsequently, among the Nafion 112 in which the anode catalyst layer 12 and the cathode catalyst layer 13 are formed in the central portion, the end portions of the four sides where the anode catalyst layer 12 and the cathode catalyst layer 13 are not formed are described above for each end portion. The aqueous ammonium chloride solution was immersed in a container for 30 minutes, and the hydrogen ions contained in the ends of the four sides of the Nafion 112 were neutralized by replacing them with ammonium ions. An exposed portion 11a substantially free of hydrogen ions was formed at the end.

  The amount of the ammonium chloride aqueous solution was set until the end of the Nafion 112 was soaked so that only the end of the Nafion 112 was immersed in the ammonium chloride aqueous solution. Next, the step (7) of Example 1 described above is performed, and the Nafion 112, the anode catalyst layer 12, the cathode catalyst layer 13, and the gas diffusion layer c are joined to form the sealing portion 16, and the electrolyte membrane-electrode joining is performed. A body (hereinafter referred to as an electrolyte membrane-electrode assembly B) was produced.

  As described above, in the present embodiment, the hydrogen ions in the portions of the electrolyte membrane 11 constituting the electrolyte membrane-electrode assembly 10 where the anode catalyst layer 12 and the cathode catalyst layer 13 are not formed are neutralized. Thus, by forming the exposed portion 11a substantially free of hydrogen ions in the electrolyte membrane 11, the resin 15 forming the sealing portion 16 of the electrolyte membrane-electrode assembly 10 is not exposed to an acidic atmosphere. Since the electrolyte does not deteriorate over time, the electrolyte membrane-electrode assembly 10 having excellent durability with no leakage of reaction gas can be produced.

(Embodiment 3)
4A is a cross-sectional view showing a schematic configuration of the fuel cell according to Embodiment 3 of the present invention, and FIG. 4B is a single cell incorporated in the fuel cell according to Embodiment 3 of the present invention. It is sectional drawing which shows schematic structure of these.

  As shown in FIG. 4 (a), the fuel cell 40 of Embodiment 3 is a fuel in which a plurality of unit cells 41 are stacked and fastened by a fastening member 43 via a pair of end plates 42 arranged at both ends thereof. A battery stack is provided.

  As shown in FIG. 4B, the unit cell 41 incorporated in the fuel cell 40 is used to supply the fuel gas to the electrolyte membrane-electrode assembly 10 and the electrolyte membrane-electrode assembly 10 shown in FIG. An anode separator 44, a cathode separator 45 for supplying an oxidant gas, and an electrolyte membrane-electrode assembly 10, an anode separator 44, and a joining member 46 for joining the cathode separator 45 are provided.

  The fuel cell 40 of the present embodiment will be specifically described below with respect to the material, structure, and action of its constituent elements. In FIG. 4, the same components as those in FIG.

  The anode separator 44 and the cathode separator 45 are composed of members having gas barrier properties and electron conductivity, and a gas supply groove for passing a fuel gas and an oxidant gas as a reaction gas is formed on the surface thereof. Yes.

The gas supply groove of the anode separator 44 is disposed in contact with the gas diffusion layer 14 of the electrolyte membrane-electrode assembly 10 and supplies fuel gas to the anode catalyst layer 12 through the gas diffusion layer 14. Further, the gas supply groove of the cathode separator 45 serves as the gas diffusion layer 1 of the electrolyte membrane-electrode assembly 10.
4, and an oxidant gas is supplied to the cathode catalyst layer 13 through the gas diffusion layer 14.

  The joining member 46 is made of a thermosetting resin whose main component is an epoxy resin, and joins the electrolyte membrane-electrode assembly 10 to the anode separator 44 and the cathode separator 45.

  Hereinafter, the unit cell 41 incorporated in the fuel cell 40 according to the present embodiment will be described in more detail based on specific examples. However, the present invention is not necessarily limited to the contents of specific raw materials and the like used below. Is not to be done.

(Example 3)
An anode separator 44 and a cathode separator 45 made of a graphite plate impregnated with resin are disposed on both surfaces of the electrolyte membrane-electrode assembly A produced in Example 1, and then the electrolyte membrane-electrode assembly A, the anode separator 44 and the cathode. An epoxy resin (manufactured by Konishi Co., Ltd., trade name: Bondquick 5) is filled in the gap between the separators 45 as a joining member 46, and the thermostat set at 50 ° C. (manufactured by Yamato Scientific Co., Ltd., model number: CKM300) By leaving it to stand for 1 hour, an epoxy resin (manufactured by Konishi Co., Ltd., trade name: Bondquick 5) was cured by heating to produce a single cell (hereinafter referred to as single cell A).

  Subsequently, in order to examine the performance of the electrolyte membrane-electrode assembly A and examine the influence on the battery performance of the fuel cell 40, a battery performance evaluation test was performed on the unit cell A.

In the battery performance evaluation test of the unit cell A, hydrogen containing 25% carbon dioxide and 50 ppm carbon monoxide was allowed to flow through the gas supply groove of the anode separator 44 of the unit cell A, and air was allowed to flow through the gas supply groove of the cathode separator 45. the cell temperature 80 ° C., a fuel utilization rate of 80%, an air utilization rate 40% 75 ° C. the dew point of the hydrogen, to set the dew point of the air to 60 ° C., the generator continuously at a current density of 0.2 a / cm ² The initial battery voltage when the battery was operated and the battery voltage after 5000 hours of operation were measured. The battery voltage of the unit cell A is as shown in (Table 1), and the unit cell A did not decrease in battery voltage even after 5000 hours of operation and exhibited excellent durability.

Example 4
Using the electrolyte membrane-electrode assembly B produced in Example 2, a unit cell (hereinafter referred to as unit cell B) was produced by the same procedure as described in Example 3, and the unit cell B was carried out. The same test as the battery performance evaluation test described in Example 3 was performed. The battery voltage of the unit cell B is as shown in (Table 1), and the unit cell B did not decrease in battery voltage even after 5000 hours of operation and showed excellent durability.

(Comparative Example 1)
The steps (1) to (5) of Example 1 described above were performed, and an anode catalyst layer and a cathode catalyst layer were formed at the center of both surfaces of the Nafion 112. Subsequently, the step (6) of Example 1 described above is not performed, and the hydrogen ions in the portion where the anode catalyst and the cathode catalyst of the Nafion 112 are not formed are not replaced, and the above-described operation is performed in a state including hydrogen ions. The process of Example 1 (7) was performed to produce an electrolyte membrane-electrode assembly (hereinafter referred to as electrolyte membrane-electrode assembly C).

  Next, using the electrolyte membrane-electrode assembly C, a unit cell (hereinafter referred to as unit cell C) is produced by the same procedure as described in Example 3, and the unit cell C is described in Example 3. The same test as the battery performance evaluation test described was performed.

The battery voltage of the unit cell C is as shown in the following (Table 1). After the unit cell C has been operated for 5000 hours, the battery voltage decreases, and the unit cells of the first and second examples (unit cells A, A, Compared with B), the durability was inferior.

  The above results are summarized in (Table 1).

単電池４１の電池性能に関し、本実施例に係る単電池（単電池Ａ，Ｂ）は、いずれも５０００時間運転後においても電池電圧の低下はなかった。

Regarding the battery performance of the unit cell 41, the unit cell (unit cells A and B) according to this example did not have a decrease in battery voltage even after operation for 5000 hours.

  This is because the exposed portion 11a of the electrolyte membrane 11 constituting the electrolyte membrane-electrode assembly 10 does not contain hydrogen ions, so that the resin 15 forming the sealing portion 16 of the electrolyte membrane-electrode assembly 10 is in an acidic atmosphere. It is considered that the durability of the electrolyte membrane-electrode assembly 10 was improved and leakage of the reaction gas from the electrolyte membrane-electrode assembly 10 could be prevented because it was not exposed and did not deteriorate over time. It is done.

  On the other hand, the unit cell (unit cell C) according to the comparative example has a lower battery voltage after 5000 hours of operation, and is inferior in durability to the unit cell (unit cells A and B) according to this example. there were.

  This is because the exposed part of the electrolyte membrane constituting the electrolyte membrane-electrode assembly contains hydrogen ions, and the resin forming the sealing part of the electrolyte membrane-electrode assembly is exposed to an acidic atmosphere over time. It is considered that the reaction gas leaked from the electrolyte membrane-electrode assembly due to deterioration.

  From the battery performance evaluation test of the unit cell 41 described above, it can be confirmed that the electrolyte membrane-electrode assembly A, B used in the present embodiment has no leakage of reaction gas and exhibits excellent durability. It was confirmed that the unit batteries A and B produced in the form of No. 1 had no battery voltage drop and exhibited excellent durability.

  As described above, in the present embodiment, the electrolyte membrane 11 constituting the electrolyte membrane-electrode assembly 10 is not covered with the anode catalyst layer 12, the cathode catalyst layer 13, and the gas diffusion layer 14 in the radially outward direction. Since the exposed exposed portion 11a does not substantially contain hydrogen ions, the durability of the electrolyte membrane-electrode assembly 10 can be improved, and thus the fuel cell 40 having excellent durability can be realized. Such a fuel cell 40 can prevent leakage of the reaction gas from the electrolyte membrane-electrode assembly 10, so that the battery voltage can be maintained over a long period of time and stable power generation can be continued.

(Modification)
Although one embodiment of the present invention has been described above, the present invention is not limited to such an embodiment, and various configurations can be adopted without departing from the spirit of the present invention.

(Modification 1)
In the above-described embodiment, Nafion 112 is used as the electrolyte membrane 11. However, the electrolyte membrane 11 has a fluorine-containing polymer as a skeleton and has functional groups such as a sulfonic acid group, a carboxyl group, and a phosphoric acid group. A hydrogen ion conductive fluorine-based resin containing hydrogen ions can be used, and for example, other electrolyte membranes such as Aciplex (registered trademark) and Flemion (registered trademark) can be used.

  Further, as the electrolyte membrane 11, a hydrogen ion conductive hydrocarbon resin containing hydrogen ions may be used with sulfonated polyphenylene, sulfonated polybenzimidazole, sulfonated polyetheretherketone, or the like as a skeleton.

(Modification 2)
In the above-described embodiment, a thermosetting epoxy resin is used as the resin 15 that forms the sealing portion 16 of the electrolyte membrane-electrode assembly 10. Examples of the resin 15 include a phenol resin and a urea resin. Other thermosetting resins can be used. Moreover, you may use thermoplastic resins, such as a polypropylene and a polyisobutylene.

(Modification 3)
In the above-described embodiment, a sodium chloride aqueous solution and an ammonium chloride aqueous solution are used as the treatment liquid 35 used for forming the exposed portion 11 a in the electrolyte membrane 11, but the treatment liquid 35 includes hydrogen contained in the electrolyte membrane 11. Basic materials that can neutralize ions can be used, such as solutions of various metal salts such as alkali metals, alkaline earth metals, transition metals, rare earths, ammonium perchlorate, ammonium sulfate, ammonium nitrate, ammonium carbonate, etc. Various non-metal salt solutions, solutions of various amines such as methylamine, diethylamine, triethylamine, and ethylenediamine can be used.

(Modification 4)
In each of the embodiments described above, platinum and ruthenium are used as the catalyst. For the catalyst, for example, noble metals such as gold, silver, rhodium, palladium, osmium, iridium, iron, nickel, manganese, cobalt, chromium, Base metals such as copper, zinc, molybdenum, tungsten, germanium, and tin, oxides of these noble metals or base metals, compounds such as complexes, alloys of these noble metals and base metals, and the like can be used.

(Modification 5)
In the above-described embodiment, acetylene black, Vulcan, Ketjen black, or the like can be used as the carbon powder supporting platinum or ruthenium as a catalyst. In addition, for example, carbon nanotubes, In addition to carbon materials such as carbon nanofibers, carbon compounds such as silicon carbide can be used.

(Modification 6)
In the above-described embodiment, a Nafion 10% dispersion is used as the ionomer. As the ionomer, a polymer having an acidic functional group excellent in heat resistance and chemical resistance can be used. For example, Flemion A perfluoroalkylsulfonic acid anomer such as (registered trademark) dispersed in an organic solvent such as ethyl alcohol or water can be used.

  In the above-described embodiment, the catalyst composition is composed of the catalyst powder, the ionomer, and the dispersion medium. However, the catalyst composition is composed of the catalyst powder and the dispersion medium without using the ionomer. Also good.

(Modification 7)
Each step (S11 to S17) related to the method for producing an electrolyte membrane-electrode assembly in the above-described embodiment is not particularly limited as long as a desired electrolyte membrane-electrode assembly can be produced. Depending on, the process order may be changed.

  As described above, the electrolyte membrane-electrode assembly according to the present invention can prevent leakage of the reaction gas, and when used in a fuel cell, maintains the battery voltage over a long period of time and generates stable power. Therefore, it can be applied to the use of fuel cells used for household cogeneration systems, power sources for electric vehicles, portable power sources, and the like.

DESCRIPTION OF SYMBOLS 10 Electrolyte membrane-electrode assembly 11 Electrolyte membrane 11a Exposed part 12 Anode catalyst layer 13 Cathode catalyst layer 14 Gas diffusion layer 15 Resin 16 Sealing part 40 Fuel cell 41 Single cell 44 Anode separator 45 Cathode separator

Claims (2)

An electrolyte membrane;
A catalyst layer disposed in the approximate center of both main surfaces of the electrolyte membrane with a smaller area than the electrolyte membrane;
A gas diffusion layer disposed outside the catalyst layer;
A resin that joins the catalyst layer and the gas diffusion layer to an exposed portion that protrudes radially outward without being covered by the catalyst layer and the gas diffusion layer of the electrolyte membrane, the catalyst layer and the gas diffusion A resin arranged around the layers;
An electrolyte membrane-electrode assembly having
The exposed portion of the electrolyte membrane is an electrolyte membrane-electrode assembly substantially free of hydrogen ions. The electrolyte membrane-electrode assembly according to claim 1,
A pair of separators sandwiching the electrolyte membrane-electrode assembly from both sides;
A fuel cell.

Images