JP5439947B2 - Membrane electrode assembly, transfer substrate for production of membrane electrode assembly, coating transfer substrate for electrode catalyst layer for production of membrane electrode assembly, and polymer electrolyte fuel cell - Google Patents

Description

  The present invention relates to a membrane electrode assembly, a transfer substrate for producing a membrane electrode assembly, a coating transfer substrate for an electrode catalyst layer for producing a membrane electrode assembly, and a polymer electrolyte fuel cell. In particular, the present invention relates to a membrane electrode assembly with improved power generation performance, a transfer substrate for producing a membrane electrode assembly, a coating transfer substrate for an electrode catalyst layer for producing a membrane electrode assembly, and a solid polymer fuel cell.

  A polymer electrolyte fuel cell has a structure in which a membrane electrode assembly formed by sandwiching a solid polymer electrolyte membrane between two electrodes (an oxidation electrode and a reduction electrode) is sandwiched between gas diffusion layers. This system generates electricity by causing an electrochemical reaction by flowing hydrogen and oxygen through the anode and cathode. Unlike conventional power generators, fuel cells generate only water in a power generation state, and are expected as clean power generators that do not generate environmentally harmful gases such as carbon dioxide, which have become a problem in recent years.

  On the other hand, as a method for producing a membrane electrode assembly, an electrode catalyst ink for fuel cells in which conductive particles carrying catalyst and a polymer having ionic conductivity are dispersed in an organic solvent is applied to a gas diffusion layer. A method of forming an electrode catalyst layer, thermocompression bonding so that the formed electrode catalyst layer and the solid polymer electrolyte membrane are in contact, or forming the electrode catalyst layer by applying the above electrode catalyst ink to a transfer film, and forming the electrode catalyst A method of thermocompression bonding so that the layer and the solid polymer electrolyte membrane are in contact with each other is known.

  The electrode catalyst layer used at this time is generally required to have high smoothness from the viewpoint of improving the adhesion with the solid polymer electrolyte membrane.

  In order to improve water repellency, after mixing a pore former such as glycerin with the electrode catalyst ink, a method of forming an electrode catalyst layer to remove the pore former and increasing the porosity, or a fluorine resin or the like is mixed with the electrode catalyst ink. The method is taken.

Japanese Patent Laid-Open No. 2004-220979 JP 2008-218131 A

  However, a simple electrode catalyst layer with high smoothness cannot provide a sufficient drainage effect particularly in a power generation state at a high current density.

  In addition, the method of mixing a pore former or a water repellent with the electrode catalyst ink has a problem in that the electric resistance of the electrode catalyst layer increases, and the output on the low current side particularly decreases.

  The present invention is capable of forming a membrane electrode assembly with good water repellency while maintaining the bondability between the electrode catalyst layer having a undulation curve and the solid polymer electrolyte membrane, and a membrane electrode assembly with improved power generation performance, It is intended to provide a transfer substrate for producing a membrane electrode assembly, a coating transfer substrate for an electrode catalyst layer for producing a membrane electrode assembly, and a polymer electrolyte fuel cell.

  As a result of intensive studies by the present inventors, it is possible to improve the catalyst performance by optimizing the average height of the undulation curve element of the electrode catalyst layer of the fuel cell membrane electrode assembly in order to solve the above problems. I understood.

The invention according to claim 1 of the present invention is a membrane electrode assembly comprising a structure that is sandwiched between the polymer electrolyte membrane a pair of electrode catalyst layers, and one of the polymer electrolyte membrane of the pair of electrode catalyst layers The average height of the waviness curve element obtained by the contour curve filter having a cut-off value of λf4 mm and λc of 0.8 mm in one direction within either surface of the pair of electrode catalyst layers is 3 μm or more. The membrane electrode assembly is 7 μm or less.

  The invention according to claim 2 of the present invention is the membrane electrode assembly according to claim 1, wherein either one of the pair of electrode catalyst layers is used as a cathode.

Invention is sandwiched claim 1 or 2 gas diffusion layer of the membrane electrode assembly of the pair according to, further, membrane electrode assembly is sandwiched between the gas diffusion layer pair according to claim 3 of the present invention it is in the separator nip and shall have a polymer electrolyte fuel cell according to claim.

  The invention according to claim 4 of the present invention is the transfer substrate for producing a membrane electrode assembly according to claim 1 or 2, wherein the surface of the transfer substrate is cut off in at least one direction in the plane. An average height of waviness curve elements obtained by a contour curve filter of λf 4 mm and λc 0.8 mm is 3 μm or more and 17 μm or less, which is used as a transfer substrate for manufacturing a membrane electrode assembly.

  The invention according to claim 5 of the present invention is an electrode catalyst-coated transfer base material for producing a membrane electrode assembly in which an electrode catalyst layer of a membrane electrode assembly is provided on a transfer base material. The catalyst surface has an average height of waviness curve elements obtained by a contour curve filter having a cutoff value of λf4 mm and λc of 0.8 mm in at least one direction in the plane, which is 7 μm or less. This is an electrode catalyst coating transfer base material.

The invention according to claim 6 of the present invention is a membrane / electrode assembly manufactured using the electrode catalyst-coated transfer substrate according to claim 5 .

Invention is sandwiched between the gas diffusion layer of the membrane electrode assembly of the pair according to claim 6, further membrane electrode assembly is sandwiched between the gas diffusion layer of the pair separator according to claim 7 of the present invention in is obtained by a polymer electrolyte fuel cell characterized in that it is sandwiched.

  According to the present invention, it is possible to form a membrane electrode assembly with good water repellency while maintaining the bondability between the electrode catalyst layer having a undulation curve and the solid polymer electrolyte membrane, and the membrane electrode junction with improved power generation performance Body, a transfer substrate for producing a membrane electrode assembly, an electrode transfer layer for an electrode catalyst layer for producing a membrane electrode assembly, and a polymer electrolyte fuel cell.

1 is a schematic exploded view showing a polymer electrolyte fuel cell according to an embodiment of the present invention. (A)-(c) is a schematic cross-sectional schematic diagram which shows the membrane electrode assembly which concerns on embodiment of this invention. It is a schematic diagram showing a membrane electrode assembly concerning an embodiment of the invention.

  Hereinafter, a membrane electrode assembly (MEA) 11 and a polymer electrolyte fuel cell 13 according to an embodiment of the present invention will be described. Note that the present invention is not limited to the embodiments described below, and modifications such as design changes can be made based on the knowledge of those skilled in the art, and such modifications are added. The embodiments may be included in the scope of the present invention.

  First, in the embodiment of the present invention, the average height of the waviness curve element will be described. These are defined by JIS B 0601: 2001.

  The surface of the electrode catalyst layer according to the embodiment of the present invention usually contains a short wavelength component (roughness), a long wavelength component (swell), and a longer wavelength component at the same time. Therefore, in the embodiment of the present invention, in order to limit the surface shape of the electrode catalyst layer, it is necessary to use the undulation component and remove the roughness component and the wavelength component longer than the undulation component for measurement. In the embodiment of the present invention, the cutoff value λf is a filter that defines the boundary between the undulation component and the longer wavelength component, and the cutoff value λc is the boundary between the roughness component and the undulation component. This is a filter to be defined. In the embodiment of the present invention, the cut-off values λf and λc are used to remove the wavelengths other than the waviness component and limit the surface shape of the electrode catalyst layer.

  In the embodiment of the present invention, the average height Wc of the waviness curve element is an average of the height Zt of the contour curve element at the measured reference length, and the height of the contour curve element is one peak. + The height of the next valley or one valley + the next mountain.

  FIG. 1 is a schematic exploded view showing a polymer electrolyte fuel cell 13 according to an embodiment of the present invention. As shown in FIG. 1, a polymer electrolyte fuel cell 13 according to an embodiment of the present invention includes a membrane electrode assembly (MEA) 11 having a polymer electrolyte membrane 1, an electrode catalyst layer 2, and an electrode catalyst layer 3. And a pair of separators 10 having an air electrode side gas diffusion layer 4, a fuel electrode side gas diffusion layer 5, a gas flow path 8 and a cooling water flow path 9.

As shown in FIG. 1, a solid polymer fuel cell 13 according to the embodiment of the present invention, the solid polymer electrolyte membrane 1 of the double-sided electrode catalyst layer 2 and the electrode catalyst layer 3 is joined is sandwiched A membrane electrode assembly (MEA) 11 is provided, and an air electrode side gas diffusion layer 4 and a fuel electrode side gas diffusion layer 5 are disposed to face the electrode catalyst layer 2 and the electrode catalyst layer 3 of the membrane electrode assembly 11. Thereby, the air electrode 6 and the fuel electrode 7 are comprised, respectively. Then, a set of separators 10 made of a conductive and impermeable material, which is provided with a gas flow path 8 for gas flow and is provided with a cooling water flow path 9 for cooling water flow on the opposing main surface, is disposed. For example, hydrogen gas is supplied as a fuel gas from the gas flow path 8 of the separator 10 on the fuel electrode 7 side. On the other hand, a gas containing oxygen, for example, is supplied as an oxidant gas from the gas flow path 8 of the separator 10 on the air electrode 6 side.

Further, the solid polymer electrolyte membrane 1 to a pair of separators 10, the electrode catalyst layer 2, the electrode catalyst layer 3, the air electrode-side gas diffusion layer 4, the fuel electrode side gas diffusion layer 5 is sandwiched. Although it is a solid polymer fuel cell 13 having a so-called single cell structure, in the embodiment of the present invention, a plurality of cells may be stacked via a separator 10 to form a fuel cell.

  Next, the electrode catalyst layer 2 and the electrode catalyst layer 3 of the membrane electrode assembly 11 according to the embodiment of the present invention will be described.

  The catalyst ink for forming the electrode catalyst layer 2 and the electrode catalyst layer 3 according to the embodiment of the present invention includes conductive particles carrying a catalyst, an ion conductive polymer, and a solvent.

  The conductive particles carrying the catalyst are composed of a carrier having conductivity and a catalytic metal having catalytic ability. The catalyst metal is not particularly limited as long as it has a catalytic action for oxygen reduction reaction at the cathode and hydrogen oxidation reaction at the anode. Specifically, for example, a transition metal simple substance, an alloy composed of a transition metal group, an oxide, a double oxide, a carbide, or a complex can be used. Among these, Pt, Pd, Ni, Ir, Rh, Co, Os, Ru, Fe, Au, Ag, Cu and the like are preferable, and it is preferable to use alloys, oxides, double oxides, carbides, complexes of this group. . In addition, the particle size of the conductive particles carrying the catalyst is preferably about 1 nm to 10 nm in consideration of the utilization rate, reactivity and stability of the catalyst metal.

  The carrier having conductivity is not particularly limited and known ones can be used, but representative examples include carbon particles, specifically carbon black, acetylene black, ketjen black, carbon nanotubes, fullerenes, Examples thereof include carbon particles such as solid acid aggregates, and one or more of these may be selected. The particle size of the conductive carrier is preferably about 10 nm to 100 nm.

  The electrode catalyst ink may be mixed with conductive particles not carrying a catalyst in addition to the conductive particles carrying a catalyst.

  The polymer contained in the electrode catalyst ink is not particularly limited as long as it has ion conductivity. However, considering the adhesion between the electrode catalyst layer 2 and the electrode catalyst layer 3 and the solid polymer electrolyte membrane 1, the solid polymer electrolyte is used. It is preferable to select the same material as the membrane 1.

  In the electrode catalyst ink according to the embodiment of the present invention, the conductive particles carrying the catalyst are preliminarily adjusted to water. This is because there is a risk of ignition when an organic solvent such as alcohol is added by the supported catalyst.

  Further, as organic solvents, alcohols such as methanol, ethanol, ethylene glycol, 1-propanol, 2-propanol, 1,2-propanediol, 1,3-propanediol, glycerin, butanol, N, N-dimethylformamide, N , N-dimethylacetamide, N-methyl-2-pyrrolidone, aprotic polar solvents such as dimethyl sulfoxide, and the like are not particularly limited so long as they can dissolve a polymer having ion conductivity and can be removed thereafter. None of these solvents may be used regardless of the above description. As the solvent, one selected from two or more is used.

  The solid content including the electroconductive particles carrying the catalyst in the electrode catalyst ink and the polymer having ion conductivity is preferably 5 wt% or more and 45 wt% or less with respect to the total solvent including water and the organic solvent. . If it is out of this range, the ink is not stable and the printability of the ink deteriorates.

  The viscosity of the electrode catalyst ink is preferably 50 mPa · s to 800 mPa · s at an ink temperature of 25 ° C. The solid content and the viscosity may be adjusted by a printing method, but by setting the solid content and the viscosity within the above range, an electrode catalyst ink having excellent coating suitability can be obtained.

  The electrode catalyst ink may be mixed with a thickener and a dispersant as appropriate. A suitable example of the carbon dispersant is an amorphous carbon into which a sulfonic acid group has been introduced. A solid acid is typically exemplified, but the carbon dispersant is not particularly limited.

  The solid content of the polymer solution having ion conductivity added to the electrode catalyst ink is desirably 1 wt% to 30 wt%.

  Examples of the mixing method in the electrode catalyst ink manufacturing method according to the embodiment of the present invention include known methods such as a planetary ball mill, a bead mill, and a homogenizer, but are not particularly limited. Since the solvent is oxidized by dissolved oxygen by the catalyst, the electrocatalyst ink is preferably dispersed in an inert gas, but may be mixed in an air atmosphere.

  As the solid polymer electrolyte membrane 1 according to the embodiment of the present invention, one having ion conductivity is preferably used. For example, as the fluorine-based solid polymer electrolyte membrane 1, Nafion (registered trademark) manufactured by DuPont, Flemion (registered trademark) manufactured by Asahi Glass Co., Ltd., Aciplex (registered trademark) manufactured by Asahi Kasei Co., Ltd., Gore Select (manufactured by Gore) Registered trademark). Examples of the hydrocarbon-based solid polymer electrolyte membrane 1 include solid polymer electrolyte membranes 1 such as sulfonated polyetherketone, sulfonated polyethersulfone, sulfonated polyetherethersulfone, sulfonated polysulfide, and sulfonated polyphenylene. There is no particular limitation. The film thickness is preferably about 20 μm to 100 μm.

  Next, a method for forming the electrode catalyst layer 2 and the electrode catalyst layer 3 and a method for producing the membrane electrode assembly 11 will be described.

  The membrane electrode assembly 11 is manufactured by applying an electrode catalyst ink to the solid polymer electrolyte membrane 1, applying an electrode catalyst ink to the gas diffusion layer, and sandwiching the electrode catalyst ink between the polymer electrolyte membrane 1 and thermocompression bonding. There are three main methods: once the electrode catalyst layer is formed on the transfer substrate, and then sandwiched between the solid polymer electrolyte membrane 1 and thermocompression bonded, any method may be used.

  Examples of the method for printing the adjusted electrocatalyst ink include, but are not limited to, a doctor blade method, a dipping method, a screen printing method, a roll coating method, a coating method such as a spray method, and a spray method. What is necessary is just to select an optimal thing with an application | coating base material.

  In one direction within the surface of the electrode catalyst layer 2 or the electrode catalyst layer 3 after drying with respect to the transfer substrate, the gas diffusion layer, and the solid polymer electrolyte membrane 1, at least one of the electrode catalyst layer 2 or the electrode catalyst layer 3; The swell obtained by the contour curve filter having a cut-off value of λf4 mm and λc of 0.8 mm in at least one direction in the surface of the electrode catalyst layer 2 or the electrode catalyst layer 3 on the surface opposite to the bonding surface with the solid polymer electrolyte membrane 1 You may apply | coat so that the average height of a curve element may be 3 micrometers or more and 15 micrometers.

  The membrane electrode assembly 11 composed of the electrode catalyst layer 2 or the electrode catalyst layer 3 having an average height of the waviness curve element of 3 μm or more and 15 μm is mixed with a pore former or a water repellent material in the electrode catalyst layer 2 or the electrode catalyst layer 3. Water repellency can be improved without any problems. When the average height of the waviness curve element is less than 3 μm, the effect of water repellency is not sufficiently observed, and when the average height exceeds 15 μm, the strength of the electrode catalyst layer 2 or the electrode catalyst layer 3 can be maintained. As a result, the bondability with the gas diffusion layer cannot be maintained, and the internal resistance becomes high.

  Since the membrane electrode assembly 11 composed of the electrode catalyst layer 2 or the electrode catalyst layer 3 having such a surface waviness curve is particularly prominent in the cathode during water generation, it can be made water repellent when used as a cathode. Increases effectiveness.

  In the embodiment of the present invention, when the electrode catalyst layer 2 and the electrode catalyst layer 3 are applied to the transfer substrate, the electrode catalyst layer 2 and the electrode catalyst layer 3 are applied to the transfer substrate and then applied to the solid polymer electrolyte. The film 1 is thermocompression bonded. Although it does not specifically limit as a transfer base material, The thing from which the electrode catalyst layer 2 and the electrode catalyst layer 3 release by thermocompression bonding is good. Specific examples include fluorine resins such as PTFE and ETFE, release materials having a surface coated with silicon resin, PET films, polymer films such as polyimide and PEEK, and metal plates such as SΜS. There is no particular limitation as long as the catalyst layer 2 and the electrode catalyst layer 3 are printed and transferred well.

  When applying the electrode catalyst layer 2 and the electrode catalyst layer 3 to the transfer substrate, at least one of the electrode catalyst layer 2 and the electrode catalyst layer 3 has a surface opposite to the bonding surface with the solid polymer electrolyte membrane 1. The transfer substrate is used with an average height of the waviness curve element obtained by the contour curve filter having a cutoff value of λf 4 mm and λc 0.8 mm in at least one direction in the plane of the electrode catalyst layer 2 or the electrode catalyst layer 3 being 3 μm or more and 17 μm. Thereby, the membrane electrode assembly 11 in which the average height of the waviness curve element is 3 μm or more and 15 μm can be manufactured.

  If the average height of the waviness curve element is less than 3 μm, the electrode catalyst layer 2 or the electrode catalyst layer 3 having a sufficient water-repellent effect cannot be produced, and if the average height of the waviness curve element exceeds 17 μm, the transfer The electrode catalyst layer 2 or the electrode catalyst layer 3 is partially left on the transfer substrate, and the strength of the produced electrode catalyst layer 2 or the electrode catalyst layer 3 is fragile.

  The transfer substrate may be wavy on the surface by performing processes such as embossing, blasting, and roughening.

  Application of Electrode Catalyst Layer for Membrane / Electrode Assembly Production with Electrocatalyst Layer 2 or Electrocatalyst Layer 3 Provided on Transfer Substrate The transfer base of the electrode catalyst layer 2 or electrode catalyst layer 3 on the transfer base In the surface, the average height of the waviness curve element obtained by the contour curve filter having cut-off values λf4 mm and λc0.8 mm in at least one direction in the plane is preferably 7 μm or less, more preferably 5 μm or less. When the coating transfer base material of the electrode catalyst layer satisfies such conditions, the coating property of the electrode catalyst layer 2 or the electrode catalyst layer 3 to the solid polymer electrolyte membrane 1 becomes good.

  When the average height of the waviness curve element is larger than 7 μm, the bonding property between the solid polymer electrolyte membrane 1, the electrode catalyst layer 2 and the electrode catalyst layer 3 is deteriorated, and the internal resistance of the membrane electrode assembly 11 is increased. End up.

  Further, the transfer of the electrode catalyst layer 2 or the electrode catalyst layer 3 to the solid polymer electrolyte membrane 1 may be performed a plurality of times. For example, the electrode catalyst layer 2 or the electrode catalyst layer 3 applied to the transfer base material is sandwiched and transferred between the solid polymer electrolyte membrane 1 (membrane electrode assembly 11), and the electrode catalyst layer 2 or the electrode catalyst is further transferred to the membrane electrode assembly 11. The layer 3 may be sandwiched and transferred. The order, the number of times, etc. do not ask | require, such as performing this several times, performing only one side, and performing alternately.

  Although it is the drying conditions after apply | coating the electrode catalyst layer in embodiment of this invention, the optimal drying temperature is 40 to 120 degreeC. The drying time depends on the solvent to be added, the coating thickness, and the drying temperature, but it is preferably about 1 minute to 2 hours. Depending on the drying temperature and drying time, an electrode catalyst layer having an average height of waviness curve elements of 3 μm or more and 15 μm can be formed.

  As a thermocompression bonding method according to the embodiment of the present invention, any means may be used as long as adhesion is good, such as a laminator and a heat press.

  Although it is the thermocompression-bonding conditions according to the embodiment of the present invention, it is about the glass transition point between the polymer having ion conductivity contained in the electrode catalyst layer and the solid polymer electrolyte membrane 1, and lower than the temperature at which the heat deterioration occurs. There is a need. The optimum conditions depend on the polymer contained in the electrode catalyst ink to be used and the solid polymer electrolyte membrane 1, but are preferably around 80 ° C. to 160 ° C. near the glass point transfer. Preferably, 140 degrees C or less is good.

  The cathode of the membrane electrode assembly 11 produced as described above has a cut-off value λf 4 mm at least in one direction in the plane of the electrode catalyst layer on the surface opposite to the bonding surface with the solid polymer electrolyte membrane 1. The average height of the waviness curve element obtained by the contour curve filter of λc 0.8 mm may be 3 μm or more and 15 μm or less. More preferably, it is 3 μm or more and 12 μm or less. The shape should just be a shape as shown, for example to Fig.2 (a)-(c). The shape of the anode may be determined depending on the operating conditions, but the surface opposite to the joint surface with the solid polymer electrolyte membrane 1 has a contour with cutoff values λf 4 mm and λc 0.8 mm in at least one direction in the plane of the electrode catalyst layer. It is preferable that the average height of the waviness curve element obtained by the curve filter is 15 μm or less.

  Further, the shape of the electrode catalyst layer only needs to satisfy the condition of the average height of the waviness curve element in one direction in the plane of the electrode catalyst layer, as shown in FIG. The shape is not particularly limited, such as a shape, a honeycomb shape, a stripe shape, a serpentine shape, or a cylindrical shape.

  Examples of the gas diffusion layer according to the embodiment of the present invention include, but are not particularly limited to, carbon paper, carbon cloth, and carbon felt. A treatment such as applying carbon particles such as carbon black to the electrode catalyst layer side or performing a water repellent treatment with a PTFE solution or the like may be performed.

  Furthermore, as the separator 10 used in the embodiment of the present invention, carbon, metal or the like can be used. The fuel cell is manufactured by assembling other accompanying devices such as a gas supply device and a cooling device.

  The membrane electrode assembly 11 according to the embodiment of the present invention has an electrode catalyst layer in which an average height of a waviness curve element obtained by a contour curve filter having cutoff values λf 4 mm and λc 0.8 mm is 3 μm or more and 15 μm or less on the cathode side. By using, water repellency can be improved while maintaining the bonding property between the electrode catalyst layer and the solid polymer electrolyte membrane 1.

  Hereinafter, the present invention will be described with reference to examples. In addition, this invention is not restrict | limited by the following Example. In all the following examples, the surface waviness was obtained using a microscope laser displacement meter (manufactured by Oplens) after the sample was adsorbed on the perforated chamber adsorption plate.

  PTFE film is used as a transfer substrate, and this is blasted to roughen the film surface so that the average height of the waviness curve element obtained by the contour curve filter with cutoff values λf 4 mm and λc 0.8 mm is 8 μm. did. The electrode catalyst ink was applied to this film with an applicator. At this time, the average height of the waviness curve element obtained by the contour curve filter having a cut-off value of λf 4 mm and λc 0.8 mm on the catalyst surface was 4 μm.

  This transfer substrate was subjected to hot pressing on a Nafion 212 film (registered trademark, manufactured by DuPont) at 140 ° C. for 10 minutes to transfer the electrode catalyst layer. By removing only the transfer substrate from this, the solid polymer electrolyte membrane 1 with an electrode catalyst layer and the membrane electrode assembly 11 were obtained. At this time, the average height of the undulation curve element obtained by the contour curve filter having the cut-off values λf 4 mm and λc 0.8 mm on the surface of the electrode catalyst layer opposite to the joint surface with the solid polymer electrolyte membrane 1 was 6 μm. . The electrode catalyst layer did not remain on the transfer substrate.

  A PTFE film was used as a transfer substrate, and an electrode catalyst ink was applied in a serpentine form by screen printing. At this time, the average height of the waviness curve element obtained by the contour curve filter having the cut-off values λf 4 mm and λc 0.8 mm on the surface of the electrode catalyst layer opposite to the joint surface with the solid polymer electrolyte membrane 1 was 5 μm.

  This transfer substrate was subjected to hot pressing at 140 ° C. for 10 minutes on a Nafion 212 film (manufactured by DuPont) to transfer the electrode catalyst layer. By removing only the transfer substrate from this, the solid polymer electrolyte membrane 1 with an electrode catalyst layer and the membrane electrode assembly 11 were obtained. At this time, the average height of the waviness curve element obtained by the contour curve filter having the cut-off values λf 4 mm and λc 0.8 mm on the surface of the electrode catalyst layer opposite to the joint surface with the solid polymer electrolyte membrane 1 was 4 μm. .

  When PTFE film is used as a transfer substrate and electrode catalyst ink is applied in a grid pattern by screen printing (this is referred to as transfer substrate 21), the side opposite to the joint surface with the solid polymer electrolyte membrane 1 The average height of the waviness curve element obtained by the contour curve filter having the cut-off values λf 4 mm and λc 0.8 mm on the surface of the electrode catalyst layer was 5 μm. Further, another PTFE film was used as a transfer substrate, and an electrode catalyst ink was applied to this using a bar coater (this is referred to as transfer substrate 22). At this time, the average height of the waviness curve element obtained by the contour curve filter having the cut-off values λf 4 mm and λc 0.8 mm on the surface of the electrode catalyst layer of the transfer substrate 22 was 2 μm.

  The electrode substrate layer was transferred to the Nafion 212 film (manufactured by DuPont) on the transfer substrate 22 by performing hot pressing at 140 ° C. for 10 minutes. Further, the transfer substrate 21 was transferred to both sides. By removing only the transfer substrate from this, the solid polymer electrolyte membrane 1 with an electrode catalyst layer and the membrane electrode assembly 11 were obtained. At this time, the average height of the undulation curve element obtained by the contour curve filter having the cut-off values λf 4 mm and λc 0.8 mm on the surface of the electrode catalyst layer opposite to the joint surface with the solid polymer electrolyte membrane 1 was 6 μm. .

  A PTFE film was used as a transfer substrate, and an electrode catalyst ink was applied thereto using a bar coater. At this time, the average height of the waviness curve element obtained by the contour curve filter having a cut-off value of λf 4 mm and λc 0.8 mm on the catalyst surface was 3 μm. This transfer substrate was subjected to hot pressing on a Nafion 212 film (manufactured by DuPont) at 140 ° C. for 10 minutes to transfer the electrode catalyst layer. When this membrane electrode assembly 11 was embossed, the average height of the waviness curve element obtained by the contour curve filter having a cut-off value of λf 4 mm and λc 0.8 mm on the surface of the electrode catalyst layer was 7 μm.

[Comparative Example 1]
A PTFE film was used as a transfer substrate, and an electrode catalyst ink was applied thereto using a bar coater. At this time, the average height of the waviness curve element obtained by the contour curve filter having a cut-off value of λf 4 mm and λc 0.8 mm on the surface of the electrode catalyst layer was 3 μm. This transfer substrate was subjected to hot pressing on a Nafion 212 film (manufactured by DuPont) at 140 ° C. for 10 minutes to transfer the electrode catalyst layer. By removing only the transfer substrate from this, the solid polymer electrolyte membrane 1 with an electrode catalyst layer and the membrane electrode assembly 11 were obtained. At this time, the average height of the waviness curve element obtained by the contour curve filter having the cut-off values λf 4 mm and λc 0.8 mm on the surface of the electrode catalyst layer opposite to the joint surface with the solid polymer electrolyte membrane 1 was 2 μm. .

  A polymer electrolyte fuel cell 13 was produced by sandwiching the membrane electrode assemblies of Examples 1, 2, 3 and Comparative Example 1 with a pair of carbon paper as a gas diffusion layer. Using a fuel cell measuring apparatus (GFT-SG1 manufactured by Toyo Technica Co., Ltd.), hydrogen gas was used as fuel, oxygen was used as an oxidant, and power generation characteristics were evaluated under a cell temperature of 80 ° C. and full humidification conditions.

The current at the start of flooding was 0.95 [A / cm ² ], 0.92 [A / cm ² ], 0.97 [A / cm ² ], 0.92 in Examples 1, 2, and 3, respectively. While it was [A / cm ² ], Comparative Example 1 was 0.86 [A / cm ² ].

  Comparing the polymer electrolyte fuel cells 13 produced in Examples and Comparative Examples, the electrode catalyst layers of Examples 1 to 3 are of the waviness curve element obtained by the contour curve filter having the cutoff values λf 4 mm and λc 0.8 mm. It can be seen that the power generation efficiency is improved by setting the average height to 3 μm or more and 15 μm or less.

DESCRIPTION OF SYMBOLS 1 ... Solid polymer electrolyte membrane, 2 ... Air electrode side electrode catalyst layer, 3 ... Fuel electrode side electrode catalyst layer, 4 ... Air electrode side gas diffusion layer, 5 ... Fuel electrode side gas diffusion layer, 6 ... Air electrode, 7 ... Fuel electrode, 8 ... Gas flow path, 9 ... Cooling water flow path, 10 ... Separator, 11 ... Membrane electrode assembly

Claims (7)

A membrane electrode assembly comprising a structure that is sandwiched between the polymer electrolyte membrane a pair of electrode catalyst layers,
The surface of the pair of electrode catalyst layers on the opposite side to the joint surface with the polymer electrolyte membrane has a cut-off value of λf 4 mm, λc 0.8 mm in one direction within one of the pair of electrode catalyst layers. The membrane electrode assembly is characterized in that the mean height of the waviness curve element obtained by the contour curve filter is 3 μm or more and 7 μm or less.   The membrane electrode assembly according to claim 1, wherein one of the pair of electrode catalyst layers is used as a cathode. The membrane electrode assembly according to claim 1 or 2 is sandwiched by the pair of gas diffusion layers, and further, the feature that the membrane electrode assembly is sandwiched between the gas diffusion layer is sandwiched by a pair of separators Solid polymer fuel cell. A transfer substrate for producing a membrane electrode assembly according to claim 1 or 2,
The film is characterized in that the surface of the transfer substrate has an average height of waviness curve elements obtained by a contour curve filter having a cutoff value of λf4 mm and λc of 0.8 mm in at least one direction in the plane of 3 μm or more and 17 μm or less. Transfer substrate for electrode assembly production. An electrode catalyst coating transfer substrate for producing a membrane electrode assembly, in which an electrode catalyst layer of a membrane electrode assembly is provided on a transfer substrate,
The catalyst surface on the transfer substrate has a mean height of waviness curve elements obtained by a contour curve filter having a cutoff value of λf4 mm and λc of 0.8 mm in at least one direction in the plane, and is a membrane electrode Electrocatalyst-coated transfer substrate for production of joined bodies. A membrane / electrode assembly produced using the electrode catalyst-coated transfer substrate according to claim 5 . The membrane electrode assembly of claim 6 is sandwiched by a pair of gas diffusion layers, further characterized in that clamping membrane electrode assembly with the gas diffusion layer is sandwiched by a pair of separators Solid polymer fuel cell.