JP2007048524A - Catalyst layer of solid polymer fuel cell, mea, and manufacturing method of them - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a catalyst layer contributing to restriction of a solid polymer electrolyte film. <P>SOLUTION: The catalyst layer 2 of the solid polymer fuel cell is composed of: a porous sheet 20; a catalyst part 21 formed by filling catalyst component 220 in the middle part of the porous sheet 20; and a protection part 22 formed by filling the catalyst component 220 in the porous sheet 20 so as to surround the catalyst part 21, or composed of: the porous sheet 20 composed of a porous part arranged at the middle part and the protection part 22 surrounding the porous part; and the catalyst part 21 formed by filling the catalyst component 210 in the porous part. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a catalyst layer for a polymer electrolyte fuel cell, and more particularly to a catalyst layer that contributes to suppression of breakage of a polymer electrolyte membrane when an MEA is formed.

  The polymer electrolyte fuel cell has a fuel electrode side separator having a fuel gas supply groove, a fuel electrode side gas diffusion layer, a fuel electrode catalyst layer, a solid polymer electrolyte membrane, an oxidant electrode catalyst layer, and an oxidant electrode side gas diffusion layer. And an oxidant electrode side separator provided with an oxidant gas supply groove. Since the solid polymer electrolyte membrane is thin, it has a problem that it is easily damaged when the fuel cell is manufactured or used. If the solid polymer electrolyte membrane is damaged, the durability of the fuel cell may be reduced.

For such a problem, for example, in Patent Document 1, an electrode catalyst layer is bonded to both surfaces of the center portion of the electrolyte membrane, and a resin is melted and solidified in a frame shape on the surface of the electrolyte membrane where the electrode catalyst layer is not bonded. An MEA in which an electrolyte membrane is reinforced by providing a formed reinforcing layer is disclosed.
JP 2003-82488 A

  However, in the MEA described in Patent Document 1, a large gap is easily formed between the reinforcing layer and the electrode catalyst layer, and the electrolyte membrane is exposed from the gap. For this reason, when a fuel cell is manufactured using the MEA described in Patent Document 1, a pinhole penetrating the electrolyte membrane is generated in a portion where the electrolyte membrane is exposed, and the fuel gas and the oxidant gas are generated. There is a risk of crossover. In addition, there is a risk that the reinforcing layer may be displaced due to expansion and contraction or deflection due to heat or load, or an end portion of the reinforcing layer may be peeled off from the electrolyte membrane.

  Then, an object of this invention is to provide the catalyst layer which contributes to suppression of the damage of a solid polymer electrolyte membrane.

  Another object of the present invention is to provide an MEA in which crossover between fuel gas and oxidant gas is suppressed.

  Furthermore, an object of the present invention is to provide an MEA in which dissociation between the solid polymer electrolyte membrane and the protective part is suppressed.

  The inventor made a catalyst layer by integrally forming a catalyst portion for performing a hydrogen oxidation reaction or an oxygen reduction reaction and a protection portion for reinforcing a solid polymer electrolyte membrane, and using the catalyst layer The inventors have found that the above problems can be solved by sandwiching a solid polymer electrolyte membrane, and have completed the present invention.

  That is, the present invention includes a porous sheet, a catalyst portion in which a central portion of the porous sheet is filled with a catalyst component, and a protective portion in which the porous sheet is filled with a protective component so as to surround the catalyst portion. A catalyst layer for a polymer electrolyte fuel cell, comprising:

  Further, the present invention comprises a porous sheet comprising a porous portion disposed in the center and a protective portion surrounding the porous portion, and a catalyst portion in which the porous portion is filled with a catalyst component. This is a catalyst layer for a polymer electrolyte fuel cell.

  According to the present invention, it is possible to provide a catalyst layer that contributes to suppression of breakage of the solid polymer electrolyte membrane.

  By using the catalyst layer of the present invention, it is possible to provide an MEA that can suppress the crossover between the fuel gas and the oxidant gas while suppressing breakage of the solid polymer electrolyte membrane.

  As illustrated in FIG. 1A, the first of the present invention surrounds the porous sheet 20, a catalyst part 21 in which a central part of the porous sheet 20 is filled with a catalyst component 210, and the catalyst part 21. Thus, the catalyst layer 2 for a polymer electrolyte fuel cell is characterized by comprising a protective part 22 in which the porous sheet 20 is filled with a protective component 220.

  In addition, as illustrated in FIG. 1B, the second aspect of the present invention is a porous sheet 20 comprising a porous portion disposed in the center and a protective portion 22 surrounding the porous portion, and a catalyst in the porous portion. It is a catalyst layer 2 for a polymer electrolyte fuel cell, characterized by comprising a catalyst part 21 filled with a component 210.

  As illustrated in FIG. 1A, a porous sheet is used as a skeleton, and a catalyst portion serving as a conventional catalyst layer is formed on the porous sheet, and a solid polymer electrolyte membrane is reinforced when an MEA is formed. From the protective part and the porous part that serve to reinforce the solid polymer electrolyte membrane when the MEA is formed as illustrated in FIG. Contributing to the prevention of breakage of the solid polymer electrolyte membrane by using the porous sheet as a skeleton and forming a catalyst layer in the porous part of the porous sheet that forms the catalyst part that functions as a conventional catalyst layer A catalyst layer is obtained.

  1A is a schematic plan view of A in FIG. 1, and B ′ of FIG. 1 is a schematic plan view of B in FIG. In the catalyst layer of the present invention, the area of the catalyst portion is preferably 0.4 times or more, more preferably 0.8 times or more with respect to the area of the catalyst layer.

  In the catalyst layer of the present invention, the inner periphery of the protective portion and the outer periphery of the catalyst portion overlap, and these mixing sites may be formed, or a gap may be formed between them, The overlapping part and the gap may not be formed.

  When the inner periphery of the protective portion and the outer periphery of the catalyst portion overlap to form these mixed portions, it is preferable from the viewpoint that the fuel gas and the oxidant gas are less likely to cross over. In this case, the width of the mixed portion in the planar direction is preferably 5 mm or less, more preferably 1 mm or less, and still more preferably 0.1 mm or less. Since the fuel gas or the oxidant gas does not reach the mixing site, if the mixing site exceeds 5 mm, the number of catalysts that do not contribute to the hydrogen oxidation reaction or the oxygen reduction reaction may increase.

  In the case where a gap is formed between the inner periphery of the protective part and the outer periphery of the catalyst part, it is preferable from the viewpoint that the increase of the catalyst that does not contribute to the hydrogen oxidation reaction or the oxygen reduction reaction can be suppressed. In this case, the width of the gap in the planar direction is preferably 1 mm or less, more preferably 0.1 mm or less. If the width of the gap exceeds 1 mm, a pinhole penetrating the electrolyte membrane is generated, and the fuel gas and the oxidant gas may cross over.

  For the above reasons, a catalyst layer in which the inner periphery of the protective part and the outer periphery of the catalyst part do not overlap and a gap is not formed between them is particularly preferable.

  Hereinafter, the porous sheet, the catalyst part, and the protective part, which are constituent elements of the catalyst layer of the present invention, will be described in detail.

(Porous sheet)
The porous sheet in the present invention serves as a skeleton of the catalyst layer, holds the catalyst part and the protective part, and further plays a role of connecting them.

  As shown in FIG. 1A, the entire surface of the porous sheet may be a porous structure, or as shown in FIG. 1B, the central portion has a porous structure and the other part has a non-porous structure. Things can be used.

  The porosity of the catalyst layer forming portion of the porous sheet is preferably 60 to 99%, more preferably 85 to 95%. When the porosity of the porous sheet is less than 60%, when a catalyst component is formed by filling the pores of the porous sheet to form a catalyst portion, electron conductivity is ensured in a direction perpendicular to the surface. If the porosity is over 99%, the rigidity of the porous sheet may be reduced. The porosity can be measured by a mercury intrusion method.

  In the case where the porous sheet has a porous structure as shown in FIG. 1A, the porosity of the protective part forming portion is not particularly limited, and can be appropriately determined depending on the protective component used.

  The porous sheet is preferably made of polytetrafluoroethylene (PTFE), carbon cloth, or polyimide, and more preferably PTFE.

  The thickness of a porous sheet is not specifically limited, The thing with the same thickness of a catalyst part and a protection part may be used, and the thing from which the thickness of a catalyst part and a protection part differs may be used.

  It is preferable to use a catalyst part and a protective part having the same thickness because the cost of the porous sheet can be suppressed. In this case, the thickness of the porous sheet is preferably 1 to 100 μm, more preferably 1 to 20 μm. When the thickness of the porous sheet is 1 μm or more, it is preferable in that a desired power generation amount can be obtained, and when it is 100 μm or less, it is preferable in that a high output can be maintained.

  When using a catalyst part and a protective part having different thicknesses, for example, when a protective part having a larger thickness than the catalyst part is used, a part of the protective part surrounds the gas diffusion layer, thereby causing gas diffusion. Even when an excessive load is applied to the layer, it is preferable in that it is possible to suppress the gas diffusion layer from being crushed so much that the gas diffusibility is significantly lowered. The preferable thickness of the porous sheet having different thickness depending on the part will be described later as the preferable thickness of the catalyst part and the preferable thickness of the protective part.

(Catalyst part)
The catalyst part in the present invention serves as a catalyst layer in a conventional fuel cell. That is, the catalyst unit performs a hydrogen oxidation reaction or an oxygen reduction reaction when the fuel cell is in operation.

  As shown in A or B of FIG. 1, the catalyst portion 21 is formed by filling a porous sheet 20 with a catalyst component 210. Although it does not specifically limit as a catalyst component, For example, the carbon support or platinum black which carry | supported the catalyst metal, and the mixture of electrolyte are mentioned preferably. The catalyst metal is not particularly limited as long as it has a catalytic action for hydrogen oxidation reaction or oxygen reduction reaction. For example, platinum, ruthenium, iridium, rhodium, palladium, osmium, tungsten, lead, iron, chromium Preferred is at least one selected from the group consisting of cobalt, nickel, manganese, vanadium, molybdenum, gallium, aluminum, and alloys thereof. Preferred examples of the carbon carrier include Ketjen Black (registered trademark) and Vulcan (registered trademark).

  Examples of the electrolyte include Nafion (registered trademark) manufactured by DuPont Co., Ltd., Flemion (registered trademark) manufactured by Asahi Glass Co., Ltd., Aciplex (registered trademark) manufactured by Asahi Kasei Chemicals Corporation, and Dowex (registered trademark) manufactured by The Dow Chemical Company. ), An engineering plastic, or a copolymer thereof having an acid group introduced therein. The catalyst component may contain various additives such as a water repellent polymer.

  Although the thickness of a catalyst part is not specifically limited, 0.1-100 micrometers is preferable, More preferably, it is 1-20 micrometers. When the thickness of the catalyst portion is 0.1 μm or more, it is preferable in that a desired power generation amount can be obtained, and when it is 100 μm or less, it is preferable in that high output can be maintained.

(Protection part)
The protective part in the present invention plays a role of reinforcing the solid polymer electrolyte membrane when the MEA is formed.

  As shown in FIG. 1A, when a porous sheet having a porous structure as shown in FIG. 1A is used, a portion where the porous sheet is filled with a protective component is used as a protective portion. In addition, when the central portion has a porous structure and the periphery of the central portion has a non-porous structure, a portion having the non-porous structure is defined as a protective portion.

The gas permeability coefficient of the protective part is preferably 1 × 10 ⁻⁹ cc · cm / cm ² · sec · cmHg or less, more preferably 1 × 10 ⁻⁸ cc · cm / cm ² · sec · cmHg or less, and still more preferably Is 0 cc · cm / cm ² · sec · cmHg. Excessive leakage of fuel gas or oxidant gas can be suppressed when it is 1 × 10 ⁻⁹ cc · cm / cm ² · sec · cmHg or less. The gas permeability coefficient can be measured with a porosimeter.

  As shown to A of FIG. 1, when the protection part 22 fills the porous sheet 20 with the protection component 220, it is although it does not specifically limit as a protection component, It is preferable to consist of resin. Preferred examples of the resin include an electrolyte, a silicon resin, or PTFE, and more preferably an electrolyte or a silicon resin. These are excellent in durability in an oxidation-reduction atmosphere and gas barrier properties.

  As the electrolyte, those described in the above-mentioned section of the catalyst part can be preferably used. As the silicone resin, TRV rubber manufactured by Shin-Etsu Silicone Co., Ltd. can be preferably used. As PTFE, Cytop (registered trademark) of Asahi Glass Co., Ltd. can be preferably used.

  1-100 micrometers is preferable and, as for the thickness of a protection part, More preferably, it is 5-20 micrometers. If the thickness of the protective part is less than 1 μm, an excessive load may be applied to the catalyst part when the MEA or fuel cell is formed, and the catalyst part may be clogged. If the thickness exceeds 100 μm, the catalyst layer and the electrolyte membrane May not be in sufficient contact, and the resistance may increase.

  When forming the MEA, a gasket or adhesive layer may be formed in the MEA to suppress gas leakage from the gas diffusion layer, but the thickness is 100 to 1000 μm and the fuel cell stack is fastened. When a protective part having a reaction force of 1 to 10 MPa is used, the protective part can also serve as a gasket or an adhesive layer. The reaction force can be measured, for example, by examining the crushing height using a servo motor type press. The fastening of the fuel cell stack means that the MEA is combined with a separator, GDL, gasket, etc. to form a unit fuel cell, the unit fuel cells are stacked, the stacked body is sandwiched between end plates, and tightened using bolts or the like. Point to.

  The third aspect of the present invention is a fuel electrode side gas diffusion layer 3a, a fuel electrode side catalyst layer 2a, a solid polymer electrolyte membrane 1, an oxidant electrode side catalyst layer 2c and an oxidant electrode side gas diffusion layer 3c as shown in FIG. The fuel electrode side catalyst layer 2a or the oxidant electrode side catalyst layer 2c is composed of the catalyst layer described above.

  By disposing the catalyst layer of the present invention on at least one surface of the solid polymer electrolyte membrane, the mechanical addition given to the solid polymer electrolyte membrane is reduced, so that the MEA is manufactured, the fuel cell is manufactured, or the fuel cell is manufactured. It is possible to suppress damage to the solid polymer electrolyte membrane that occurs during operation.

  As described above, the catalyst layer of the present invention may be disposed on at least one side of the solid polymer electrolyte membrane, but more preferably on both surfaces of the solid polymer electrolyte membrane. By disposing on both surfaces, damage to the solid polymer electrolyte membrane can be further suppressed.

  The fuel electrode side gas diffusion layer, the solid polymer electrolyte membrane, and the oxidant electrode side gas diffusion layer included in the MEA are not particularly limited, and conventionally known ones can be used.

  As shown in the MEA partial cross-sectional schematic diagram shown in FIG. 3, the MEA of the present invention has a gasket 31 disposed on the protective portion 22 so as to surround the fuel electrode side gas diffusion layer 3a or the oxidant electrode side gas diffusion layer 3c. May be. By disposing the gasket, leakage of fuel gas from the side surface of the fuel electrode side gas diffusion layer or leakage of oxidant gas from the side surface of the oxidant electrode side gas diffusion layer can be suppressed. Although it does not specifically limit as a gasket, Silicone rubber or fluororubber etc. are mentioned preferably.

  As shown in the MEA partial cross-sectional schematic diagram shown in FIG. 4, the MEA of the present invention has an adhesive layer 32 disposed on the protective portion 22 so as to surround the fuel electrode side gas diffusion layer 3a or the oxidant electrode side gas diffusion layer 3c. You may do it. By disposing the adhesive layer, it is possible to suppress leakage of fuel gas from the side surface of the fuel electrode side gas diffusion layer or leakage of oxidant gas from the side surface of the oxidant electrode side gas diffusion layer. When the adhesive layer is used, the total thickness of the protective layer 22 and the adhesive layer 31 is 0.5 to 0.8 times the total thickness of the catalyst layer 21 and the gas diffusion layers (3a, 3c). Preferably there is. When it is less than 0.5 times, when a polymer electrolyte fuel cell is formed by sandwiching MEA with a pair of separators, an excessive load is applied to the gas diffusion layer, and the gas flow path provided in the separator diffuses gas. May be clogged by layers. If it exceeds 0.8 times, the gas diffusion layer and the catalyst layer may not be sufficiently contacted and the resistance may increase.

  Although it does not specifically limit as an adhesive layer, A silicon type adhesive agent etc. are mentioned preferably.

  A fourth aspect of the present invention is the above-described method for producing a catalyst layer.

  1A and 1B, a method for producing a catalyst layer in which a catalyst sheet and a protective part are formed on a porous sheet using the porous sheet exemplified in FIG. And a method for producing a catalyst layer in which a catalyst portion is formed in a porous portion of the porous sheet using a porous sheet composed of a porous portion as a skeleton, is described below as catalyst layer production method 2, but the present invention is limited to these. Not.

(Catalyst layer production method 1)
1A, the porous sheet 20, the catalyst part 21 in which the catalyst component 210 is filled in the center of the porous sheet 20, and the porous sheet 20 so as to surround the catalyst part 21. In the case of producing the catalyst layer 2 composed of the protective part 22 filled with the protective component 220, the step (i) of forming the protective part by applying and drying the protective component mixed solution on the porous sheet and drying the porous part A method of forming the catalyst part by applying and drying the catalyst slurry on the central part of the quality sheet and forming the catalyst part (ii), and forming the protective part so as to surround the catalyst part is preferable. The steps (i) and (ii) are in no particular order, and the order of performing these steps can be determined as appropriate.

  Below, the method of producing a catalyst layer in order of step (i) step (ii) is shown. However, the present invention is not limited to the following steps.

  As step (i), first, a porous sheet is prepared. As the porous sheet, those described in the above-mentioned section of the catalyst layer can be preferably used.

  Next, the protective component mixture is applied to the porous sheet. Preferred examples of the protective component mixture include those obtained by adding a resin to a solvent. As resin, what was described in the term of the protection part is preferable. The solvent is not particularly limited as long as it dissolves the resin and does not dissolve the porous sheet. The method for applying the protective component mixed liquid to the porous sheet is not particularly limited, but the spray method, screen printing, or the protective component mixed liquid is dropped on the porous sheet, and then traced with a rod or a rod made of glass or PTFR. A method of press-fitting is preferable. The protective component mixed solution is filled so as to surround the catalyst portion formation planned portion in the center of the porous sheet.

  Next, the protective component mixed solution is dried to form protective portions in the pores of the porous sheet. Preferable examples of the method for removing the solvent from the protective component mixture include natural drying, ventilation drying, heat drying, and reduced pressure.

  Subsequently, as a step (ii), the catalyst slurry is applied to the central portion of the porous sheet. Although it does not specifically limit as a catalyst slurry, The thing etc. which mixed the carbon support | carrier which carry | supported the catalyst metal as a protective component, or platinum black and an electrolyte in a solvent are mentioned preferably. The carbon carrier, platinum black, and electrolyte supporting the catalyst metal are as described in the above-mentioned section of the catalyst part. The solvent is not particularly limited as long as it dissolves the protective component and does not dissolve the porous sheet. For example, alcohol, water, or a mixture of alcohol and water is preferable. Preferred examples of the alcohol include methanol, ethanol, propanol, isopropanol, sec-butanol, and tert-butanol, and more preferably ethanol or isopropanol. These are excellent in non-reactivity with electrolytes and electrode catalysts, dispersibility, and volatility. The method for applying the catalyst slurry to the porous sheet is not particularly limited, and preferred examples include a spray method, a die coater method, a doctor blade method, gravure coating, screen printing, or mixed liquid jet printing.

  Next, the catalyst slurry is dried to form catalyst parts in the pores of the porous sheet. Preferred examples of the method for removing the solvent from the catalyst slurry include natural drying, ventilation drying, heat drying or reduced pressure.

  When applying the protective component mixture, it is preferable to mask the catalyst portion or the catalyst portion formation planned portion, and when applying the catalyst slurry, masking the protection portion or the protection portion formation planned portion. Continuous production is possible by masking. A resin sheet or the like is used as a masking sheet for masking.

  When applying the protective component mixture or the catalyst slurry to the porous sheet, place the porous sheet on a plate with air permeability, and make the surface that does not have the porous sheet a negative pressure. Thus, the penetration of the protective component mixture or the catalyst slurry can be promoted, and the protective component mixture or the catalyst slurry can be penetrated to every corner of the porous sheet.

  In the above-mentioned catalyst layer section, as an advantage that the inner periphery of the protective portion and the outer periphery of the catalyst portion overlap to form these mixed portions, the fuel gas and the oxidant gas are less likely to cross over. Although mentioned, below, the method of overlapping the inner periphery of a protection part and the outer periphery of a catalyst part and forming these mixing parts is described.

  Step (i) of forming a protective part by applying and drying a protective component mixture on the porous part of the porous sheet after masking the catalyst part formation planned part of the porous sheet, followed by masking The protective part is masked so that the inner periphery of the protective part is exposed, and the step (ii) of forming the catalyst part by applying and drying the catalyst slurry on the porous sheet, These mixed portions can be formed by overlapping the outer periphery of the catalyst portion. According to this method, the amount of the catalyst that does not contribute to the catalytic reaction can be reduced because the width of the mixing portion between the protective portion and the catalyst portion is not excessively widened. The width of the mixed portion can be adjusted by the width of the inner periphery exposed from the masking sheet when masking the protective part. The preferable width of the mixing part is as described in the above-mentioned section of the catalyst layer.

  In the above-mentioned catalyst layer section, as an advantage that a gap is formed between the inner periphery of the protective part and the outer periphery of the catalyst part, an increase in the catalyst that does not contribute to the hydrogen oxidation reaction or the oxygen reduction reaction can be suppressed. However, a method for forming a gap between the inner periphery of the protective part and the outer periphery of the catalyst part will be described below.

  Step (i) of forming a protection part by applying and drying a protective component mixture after masking the catalyst part formation planned part of the porous sheet, removing the masking, and separating the boundary between the protection part and the catalyst part formation planned part Forming a boundary portion filled with components (i ′), masking the protective portion, applying and drying the catalyst slurry on the porous sheet, removing the mask to form the catalyst portion (ii), and By performing the step (ii ′) of removing the separation component in this order, a gap can be formed between the inner periphery of the protection part and the outer periphery of the catalyst part. According to this method, since the width of the gap between the protective part and the catalyst part does not spread too much, the crossover between the fuel gas and the oxidant gas can be suppressed. The preferable width of the gap is as described in the above-mentioned section of the catalyst layer.

  Moreover, it is also preferable to form a catalyst layer in the procedure shown below. Applying the protective component mixture liquid to the catalyst portion formation planned portion of the porous sheet and then drying it to form the protective portion, and removing the separation component and applying the catalyst slurry to the porous sheet and By performing the drying steps in this order, a gap can also be formed between the inner periphery of the protective part and the outer periphery of the catalyst part. According to this method, since the width of the gap between the protective part and the catalyst part does not spread too much, the crossover between the fuel gas and the oxidant gas can be suppressed. The preferable width of the gap is as described in the above-mentioned section of the catalyst layer.

  Preferred examples of the separation component include paraffin and octylphenoxypolyethoxyethanol, and paraffin is more preferable.

  Preferred examples of the method for removing the separation component include vaporization at elevated temperature, washing with a solvent, and the like, which can be appropriately determined depending on the porous sheet to be used, the separation component, and the like. Of these, the removal method by vaporization at elevated temperature is more preferable because it is a simple means. As a removal method by temperature rising vaporization, for example, in step (i ′), a separation component having a boiling point lower than the melting point of the porous sheet is used, and in step (ii ′), the porous sheet has a boiling point equal to or higher than the boiling point of the separation component. It is preferable to perform the heat treatment at a temperature lower than the melting point because the separation component can be removed while suppressing deformation or deterioration of the porous sheet.

  The width of the boundary portion can be adjusted by the width of filling the separation component.

(Catalyst layer production method 2)
The porous part 20 which consists of the porous part arrange | positioned in the center illustrated in FIG. 1B and the protection part 22 surrounding the said porous part, and the catalyst part by which the catalyst component 210 is filled into the said porous part When the catalyst layer 2 comprising 21 is produced, a catalyst slurry is applied to the porous part of the porous sheet having a porous part at the center, impregnated and impregnated, and then dried to produce the catalyst layer Are preferred. In addition, a catalyst sheet is formed by applying and drying a catalyst slurry on a porous sheet having a porous structure on the entire surface, and a protective part in which a film is formed into a frame shape, and the catalyst part is formed on the protective part. A method in which the catalyst layer is formed by integrating the catalyst portion and the protection portion by means of heating or the like by fitting in the cavity is also preferred.

  As the catalyst slurry, those described in the above-mentioned catalyst layer production method 1 are preferable, and as the method for removing the solvent from the catalyst slurry or the method for applying the catalyst slurry, the method described in the above-mentioned catalyst layer production method 1 is preferable.

  A fifth aspect of the present invention is the above-described MEA manufacturing method.

  The MEA of the present invention comprises a fuel electrode side catalyst layer, a solid polymer electrolyte membrane, and an oxidant electrode side catalyst layer; or a fuel electrode side gas diffusion layer, a fuel electrode side catalyst layer, a solid polymer electrolyte membrane, and an oxidant electrode. A side catalyst layer and an oxidant electrode side gas diffusion layer (hereinafter also referred to as a laminate) are produced by hot pressing, and as the fuel electrode side catalyst layer or the oxidant electrode side catalyst layer, Any of the catalyst layers described above is used. It is more preferable to use the above-mentioned catalyst layers as the fuel electrode side catalyst layer and the oxidant electrode side catalyst layer because the damage of the solid polymer electrolyte membrane can be further suppressed.

  The laminate may be a laminate of a fuel electrode side gas diffusion layer, a fuel electrode side catalyst layer, a solid polymer electrolyte membrane, an oxidant electrode side catalyst layer, and an oxidant electrode side gas diffusion layer, or a fuel electrode side. A catalyst layer, a solid polymer electrolyte membrane, and an oxidant electrode side catalyst layer integrated in advance may be sandwiched between a fuel electrode side gas diffusion layer and an oxidant electrode side gas diffusion layer, or fuel electrode side gas diffusion The layer and the fuel electrode side catalyst layer may be integrated, the oxidant electrode side gas diffusion layer and the oxidant side catalyst layer may be integrated, and the solid polymer electrolyte membrane may be sandwiched between these layers and further integrated. . A method for integrating the fuel electrode side catalyst layer, the solid polymer electrolyte membrane and the oxidant electrode side catalyst layer, a method for integrating the fuel electrode side gas diffusion layer and the fuel electrode side catalyst layer, and an oxidant electrode side gas The method for integrating the diffusion layer and the oxidant side catalyst layer is not particularly limited, and a conventionally known method can be used.

  The pressing is preferably performed at 1 to 8 MPa, more preferably 2 to 3 MPa. If the pressing pressure is less than 1 MPa, the constituent elements of the laminate may not be in close contact with each other, and the battery performance may be deteriorated. If it exceeds 8 MPa, the pores of the gas diffusion layer or the catalyst layer may be blocked. Moreover, it is preferable to perform the said press at 120-180 degreeC, More preferably, it is 120-130 degreeC. If the press temperature is less than 120 ° C, the components of the laminate may not be in close contact with each other, and the battery performance may be deteriorated. If it exceeds 180 ° C, the solid polymer electrolyte membrane, the fuel electrode side catalyst layer, or the oxidant There is a possibility that the electrolyte contained in the electrode catalyst layer may deteriorate.

  However, in the step (ii) of forming the catalyst part by applying and drying the catalyst slurry on the porous sheet described in the catalyst layer production method 1 above, the catalyst layer is filled with the catalyst slurry without being dried. When a laminated body is formed in a state, pressing can be performed at a lower pressure and temperature. This is because the catalyst slurry is softer than the solidified catalyst slurry, so that the components of the laminate can be brought into close contact with each other even when pressed at a lower pressure and temperature. In this case, the pressing is preferably performed at 2 to 4 MPa and 20 to 140 ° C, more preferably 2 to 2.5 MPa and 20 to 120 ° C. By pressing at the pressure and temperature described above, the pores of the gas diffusion layer or catalyst layer are blocked, or the electrolyte contained in the solid polymer electrolyte membrane, the fuel electrode side catalyst layer, or the oxidant electrode side catalyst layer Deterioration can be further suppressed.

  The protective component or the porous sheet is selected so that the melting point of the protective part is lower than the deterioration temperature of the electrolyte contained in the solid polymer electrolyte membrane, the fuel electrode side catalyst layer, or the oxidant electrode side catalyst layer. It is preferable to perform pressing under a temperature condition that is higher than the higher melting point of the electrolyte and lower than the deterioration temperature of the electrolyte. According to this, deterioration of the electrolyte can be suppressed.

  As described in the MEA section, by disposing a gasket on the protective part so as to surround the fuel electrode side gas diffusion layer or oxidant electrode side gas diffusion layer, leakage of fuel gas or oxidant gas is suppressed. it can.

  The arrangement of the gasket is not particularly limited, but it is preferably performed by integral formation.

  As described in the MEA section, by disposing an adhesive layer on the protective portion so as to surround the fuel electrode side gas diffusion layer or the oxidant electrode side gas diffusion layer, leakage of the fuel gas or oxidant gas can be prevented. In addition, dissociation between the protective part and the solid polymer electrolyte membrane can be suppressed.

  The arrangement of the adhesive layer is not particularly limited, but is preferably performed by application by a dispenser or screen printing.

  The polymer electrolyte fuel cell including the above-described catalyst layer or MEA or the catalyst layer or MEA produced by the above-described method has excellent durability of the fuel cell because damage to the solid polymer electrolyte membrane is suppressed. .

  EXAMPLES Next, although an Example is given and this invention is demonstrated concretely, these Examples do not restrict | limit this invention at all.

Example 1
The MEA having the form shown in FIG. 3 was produced by the following method. As a gas diffusion layer, carbon paper with a carbon layer (manufactured by Japan Gore-Tex Co., Ltd., CFP200) was immersed in pure water and washed, and then dried at 80 ° C. in a drying furnace. An electrolyte solution (Du Pont Corp., DE520) was prepared as a protective component mixture. As catalyst slurry, 10 g of platinum-supporting carbon (manufactured by Tanaka Kikinzoku Co., Ltd., TEC10E50E), 100 g of perfluorosulfonic acid electrolyte solution (manufactured by DuPont, 5% Nafion solution), 100 g of pure water, and 100 g of isopropanol are mixed. A uniform dispersion was prepared.

  A PTFE sheet having a thickness of 20 μm, a size of 20 × 20 cm, and a porosity of 90% was prepared as a porous sheet, and the porous sheet was sandwiched between workpieces made of stainless steel having an outer diameter of 20 × 20 cm and an inner diameter of 16 × 16 cm.

  Next, a porous sheet provided with a workpiece was placed on one side of a sintered metal plate having a pore diameter of 100 μm or less, and the surface of the sintered metal plate on which the porous sheet was not placed was decompressed by an aspirator. Next, a masking sheet made of a polyimide adhesive film cut to 5 × 6 cm is placed on the center of the porous sheet, and the porous sheet is impregnated with the protective component mixture using a screen printing method, and then heated at 60 ° C. It dried and formed the protection part in the porous sheet.

  Next, a gasket made of silicon rubber was formed on the protective portion by integral formation.

  Next, the masking sheet was removed, and the catalyst slurry was atomized and applied to the porous sheet using a spray-type coating apparatus, and then heated and dried at 60 ° C. to form a catalyst portion in the porous sheet.

  Next, the workpiece | work was removed and the location in which the protection part was not formed in the outer periphery of the porous sheet was cut, and the catalyst layer was obtained.

  In the obtained catalyst layer, a gap was formed between the protective part and the catalyst part, and the width of the gap was 0.5 mm. The width of the gap was measured with an optical microscope.

The gas permeability coefficient of the protective layer obtained is 1 × 10 ⁻⁹ cc · cm / cm ² · sec · cmHg or less.

  As the solid polymer electrolyte membrane, Nafion (registered trademark, 117) manufactured by DuPont was prepared. The polymer electrolyte membrane was sandwiched between a pair of catalyst layers, and further sandwiched between a pair of gas diffusion layers, and then heated and pressurized at 140 ° C. and 3 MPa to obtain MEA.

(Comparative Example 1)
As the solid polymer electrolyte membrane, Nafion (registered trademark, 117) manufactured by DuPont was prepared. As a reinforcing layer, a polyethylene naphthalate sheet having a thickness of 10 μm formed in a frame shape so that the catalyst layer fits in the center portion was prepared.

  The catalyst slurry used in Example 1 was atomized and applied onto a transfer sheet made of Teflon using a spray type coating apparatus, and the catalyst slurry was dried at 40 ° C. for 60 minutes to form a catalyst layer on the transfer sheet.

  Next, the solid polymer electrolyte membrane was sandwiched between a pair of transfer sheets so that the catalyst layer and the solid polymer electrolyte membrane were in contact, and heated and pressurized at 140 ° C. and 3 MPa.

  Next, a silicon adhesive (product name, one-component TRV rubber, KE45) manufactured by Shin-Etsu Silicone Co., Ltd. is applied to one side of the pair of protective parts, and is attached to both sides of the solid polymer electrolyte membrane so as to surround the catalyst layer. I attached.

  Next, a gasket made of silicon rubber was formed on the protective part by adhesion.

  Next, it was sandwiched between a pair of gas diffusion layers and heated and pressurized at 140 ° C. and 3 MPa to obtain MEA. A schematic cross-sectional view of the MEA of Comparative Example 1 is shown in FIG. In FIG. 5, the code | symbol 9 shows a reinforcement layer.

(Comparative Example 2)
An MEA was obtained in the same manner as in Comparative Example 1 except that no protective part was provided and that the gasket was separate from the MEA. FIG. 6 shows a schematic cross-sectional view of the MEA of Comparative Example 2.

(Battery fabrication and power generation evaluation)
FIG. 7 shows the results of producing a cell battery using the MEAs obtained in Example 1 and Comparative Examples 1 and 2 and measuring the durability performance.

The cell battery has an effective catalyst area of 30 cm ² , and the cell is formed by laminating an end plate, an insulating plate, a current collecting plate, and a separator in pairs from the outside so that the end plate at both ends is subjected to a pressure of 3 MPa on the MEA. Fastened with bolts.

Further, hydrogen gas having a relative humidity of 70% was flowed to the anode, and air having a relative humidity of 60% was flowed to the cathode, and a load of 1.2 A / cm ² was taken, and power generation evaluation was performed.

  As can be seen from FIG. 7, when the MEA of the present invention is used, the durability is higher than when the MEA of the comparative example is used.

  When the cell battery using the MEA of Comparative Example 1 was observed after the power generation test, a twist was observed in the part where the gasket of the protective part was arranged, and a gap of 500 μm at the longest was formed between the protective part and the catalyst layer, The part where the electrolyte membrane was exposed was seen. Further, it was confirmed by a leak test that a pinhole penetrating the electrolyte membrane was generated at a portion where the electrolyte membrane was exposed.

  When the cell battery using the MEA of Comparative Example 2 was observed after the power generation test, it was confirmed that a pinhole penetrating the electrolyte membrane was generated at a location where the electrolyte membrane was exposed by a leak test.

It is the cross-sectional schematic and planar schematic which show the catalyst layer of this invention. It is a section schematic diagram of MEA. It is a partial section schematic diagram of MEA provided with a gasket. It is a partial section schematic diagram of MEA provided with the adhesion layer. 3 is a schematic cross-sectional view of an MEA of Comparative Example 1. FIG. 6 is a schematic cross-sectional view of an MEA of Comparative Example 2. FIG. It is a figure which shows the durable performance measurement result of the cell battery provided with MEA of Example 1, the comparative example 1, or the comparative example 2.

Explanation of symbols

1 solid polymer electrolyte membrane,
2 catalyst layer,
2a Fuel electrode side catalyst layer,
2c oxidant electrode side catalyst layer,
3a Fuel electrode side gas diffusion layer,
3c Oxidant electrode side gas diffusion layer,
9 Reinforcing layer,
10 MEA,
20 porous sheet,
21 Catalyst part,
22 Protection part,
31 gasket,
32 adhesive layer,
210 catalyst component,
220 Protective ingredient.

Claims (18)

A porous sheet;
A catalyst portion in which a catalyst component is filled in a central portion of the porous sheet;
A catalyst layer for a polymer electrolyte fuel cell, comprising: a protective portion in which the porous sheet is filled with a protective component so as to surround the catalyst portion. A porous sheet consisting of a porous part disposed in the center and a protective part surrounding the porous part;
A catalyst layer for a polymer electrolyte fuel cell, comprising a catalyst part in which the porous part is filled with a catalyst component.   The catalyst layer according to claim 1, wherein the protective component is a resin.   The catalyst layer according to claim 3, wherein the resin is an electrolyte, a silicon resin, or polytetrafluoroethylene. The inner periphery of the protection part and the outer periphery of the catalyst part overlap, and a mixing part of the protection part and the catalyst part is formed,
The catalyst layer according to any one of claims 1 to 4, wherein a width of the mixed portion in a planar direction is 5 mm or less. A gap is formed between the inner periphery of the protective part and the outer periphery of the catalyst part,
The catalyst layer according to any one of claims 1 to 5, wherein a width of the gap in a planar direction is 1 mm or less.   The catalyst layer according to claim 1, wherein the porous sheet is made of polytetrafluoroethylene. An MEA comprising a fuel electrode side gas diffusion layer, a fuel electrode side catalyst layer, a solid polymer electrolyte membrane, an oxidant electrode side catalyst layer and an oxidant electrode side gas diffusion layer,
The MEA, wherein the fuel electrode side catalyst layer or the oxidant electrode side catalyst layer is the catalyst layer according to any one of claims 1 to 7. Furthermore, a gasket is included on the protective part,
9. The MEA according to claim 8, wherein the gasket is disposed so as to surround the fuel electrode side gas diffusion layer or the oxidant electrode side gas diffusion layer. Furthermore, an adhesive layer is included on the protective part,
9. The MEA according to claim 8, wherein the adhesive layer is disposed so as to surround the fuel electrode side gas diffusion layer or the oxidant electrode side gas diffusion layer.   The combined thickness of the protective layer and the adhesive layer is 0.5 to 0.8 times the combined thickness of the catalyst layer and the gas diffusion layer. The MEA as described. Applying and drying the protective component mixture on the porous sheet and drying to form a protective part (i), and applying and drying the catalyst slurry to the central part of the porous sheet to form the catalyst part (ii) Including
The method for producing a catalyst layer for a polymer electrolyte fuel cell, wherein the protective part is formed so as to surround the catalyst part. Between the step (i) and the step (ii), a step (i ′) of forming a boundary part by filling a boundary component between the protective part and the catalyst part formation planned part,
The method according to claim 12, further comprising the step (ii ') of removing the separation component after the step (ii). The boiling point of the separation component is less than the melting point of the porous sheet,
The manufacturing method according to claim 13, wherein the step (ii ′) is performed by heat treatment at a temperature equal to or higher than a boiling point of the separation component and lower than a melting point of the porous sheet.   The method according to claim 13 or 14, wherein the separation component is paraffin or octylphenoxypolyethoxyethanol. Stacking the fuel electrode side catalyst layer, the solid polymer electrolyte membrane, and the oxidant electrode side catalyst layer and hot pressing at 120 to 180 ° C. and 1 to 8 MPa;
Drying after the hot pressing, and
The catalyst layer according to any one of claims 1 to 7 or the catalyst layer produced by the method according to any one of claims 12 to 15 is used as the fuel electrode side catalyst layer or the oxidant electrode side catalyst layer. MEA manufacturing method characterized by the above-mentioned. The fuel electrode side catalyst layer, the solid polymer electrolyte membrane, and the oxidant electrode side catalyst layer are laminated and pressed,
The method according to any one of claims 12 to 15, wherein the catalyst layer produced without drying in the step (ii) is used as the fuel electrode side catalyst layer or the oxidant electrode side catalyst layer. The manufacturing method of MEA. The melting point of the protective part is less than the deterioration temperature of the electrolyte contained in the solid polymer electrolyte membrane, the fuel electrode side catalyst layer, or the oxidant electrode side catalyst layer,
18. The manufacturing method according to claim 16, wherein the pressing is performed under a temperature condition that is equal to or higher than a higher melting point of the protective part or the electrolyte and lower than a deterioration temperature of the electrolyte.

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