JP5266832B2 - Catalyst layer for polymer electrolyte fuel cell, catalyst layer transfer sheet, catalyst layer-electrolyte membrane laminate, and polymer electrolyte fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a new catalyst layer for a polymer electrolyte fuel cell and a transfer sheet. <P>SOLUTION: The catalyst layer for the polymer electrolyte fuel cell is composed of an agglomerate containing catalyst-carried carbon particles and a hydrogen ion conductive polymer electrolyte, and in the agglomerate, a porosity of pores having a pore size of 10-500 nm is 4 to 15%, that of pores having a pore size of 1-50 &mu;m is 7 to 25%, an active surface area per unit weight of catalyst is 450 to 600 cm<SP>2</SP>/mg, and the average particle diameter of the agglomerate is 50 to 200 nm. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a novel catalyst layer for a polymer electrolyte fuel cell, a catalyst layer transfer sheet, a catalyst layer-electrolyte membrane laminate, and a fuel cell.

  A fuel cell is a system that generates electric power through an electrochemical reaction between hydrogen and oxygen, and has attracted attention as a next-generation clean energy system. One type of fuel cell is a polymer electrolyte fuel cell.

  The polymer electrolyte fuel cell uses a hydrogen ion conductive polymer electrolyte membrane as an electrolyte membrane, and employs a structure in which a catalyst layer, an electrode base material, and a separator are sequentially laminated on both surfaces of the membrane.

  Among these structures, the catalyst layer generates power by a chemical reaction, and thus greatly affects power generation performance. Therefore, in order to improve the power generation performance, research and development of the structure of the catalyst layer has been actively conducted.

For example, Patent Document 1 discloses an electrode in which a catalyst layer made of at least a solid polymer electrolyte and a carbon powder supporting a noble metal catalyst is formed on one side of a gas diffusion layer, the diameter of the catalyst layer being 0.04 to 1 An electrode for a polymer electrolyte fuel cell having a specific volume of 0.0 μm pores of 0.04 cm ³ / g or more is disclosed.

However, Patent Document 1 does not teach any specific structure of the catalyst layer.
JP 9-92293 A

  An object of this invention is to provide the novel catalyst layer which comprises a solid polymer fuel cell, and the transfer sheet provided with the same.

  As a result of intensive studies in view of the above-described conventional techniques, the present inventors have found that the battery layer has excellent battery performance by employing a catalyst layer having a specific structure.

  That is, the present invention relates to the following polymer polymer fuel cell catalyst layer, catalyst layer transfer sheet and the like.

Item 1. (1) Consists of an agglomerate containing catalyst-supporting carbon particles and a hydrogen ion conductive polymer electrolyte,
(2) The void ratio occupied by voids having a pore diameter of 10 nm to 500 nm is 8 to 10 %,
(3) The void ratio occupied by voids having a pore diameter of 1 μm to 50 μm is 7 to 25%.
Catalyst layer for polymer electrolyte fuel cell.

  Item 2. Item 2. The catalyst layer according to Item 1, wherein the average particle size of the aggregate comprising the catalyst-supporting carbon particles and the hydrogen ion conductive polymer electrolyte is 50 to 200 nm.

Item 3. Item 3. The catalyst layer according to Item 1 or 2, wherein the active surface area per unit weight of the catalyst in the catalyst-supporting carbon particles is 450 to 600 cm ² / mg.

  Item 4. Item 4. A catalyst layer transfer sheet, wherein the catalyst layer according to any one of Items 1 to 3 is formed on a transfer substrate.

  Item 5. Item 5. A catalyst layer-electrolyte membrane laminate obtained by transferring the catalyst layer transfer sheet according to Item 4 to an electrolyte membrane.

  Item 6. Item 6. A polymer electrolyte fuel cell comprising the catalyst layer-electrolyte membrane laminate according to Item 5.

  The catalyst layer of the present invention is (1) the catalyst layer is composed of an agglomerate containing catalyst-supporting carbon particles and a hydrogen ion conductive polymer electrolyte, and (2) the porosity occupied by voids having a pore diameter of 10 nm to 500 nm. The catalyst layer for a polymer electrolyte fuel cell is 4 to 15%, and (3) the porosity of the pores having a pore diameter of 1 μm to 50 μm is 7 to 25%.

Catalyst-supporting carbon particles The catalyst-supporting carbon particles are those in which a catalyst material is supported on carbon particles, and known or commercially available ones can be used.

  The average particle size of the catalyst-supporting carbon particles is usually about 10 to 100 nm, preferably about 20 to 80 nm, and most preferably about 40 to 50 nm.

Active surface area per unit weight of the catalyst in the catalyst supporting carbon particles contained in the catalyst layer of the present invention is preferably ^{450~600cm 2 / mg, 500~580cm 2 /} mg is more preferable. By having an active surface area in this range, the catalyst layer of the present invention has good reactivity, and can exhibit excellent current-voltage characteristics, and thus excellent battery characteristics.

In the present invention, the active surface area per unit weight of the catalyst in the catalyst-supported carbon particles can be measured by a cyclic voltammetry (CV) method. For example, the case where platinum is used as a catalyst will be simply described. Nitrogen is passed to the electrode side (hereinafter referred to as electrode A) to be measured and hydrogen is sufficiently humidified to flow through the other electrode (hereinafter referred to as electrode B), and electrode B is used as a reference electrode. The cleaning process is performed by scanning the potential of the electrode in the range of 0.07 V to 1.00 V (vs RHE), for example. Thereafter, the amount of hydrogen adsorption / desorption is determined from a CV curve obtained by performing potential scanning in the range of 0.07 V to 0.60 V (vs RHE) at a scanning speed of 0.1 V / s. Assuming that one hydrogen atom is adsorbed on one platinum atom, the active surface area of platinum is calculated from the amount of electricity per unit area (210 μC / cm ² ) on the surface of the polycrystalline platinum. The active surface area per weight can be calculated by dividing the platinum active surface area thus obtained by the weight of the platinum catalyst contained in the catalyst layer.

  The carbon particles constituting the catalyst-supported carbon particles are not particularly limited, and examples thereof include carbon black such as channel black, furnace black, ketjen black, acetylene black, and lamp black, graphite, activated carbon, carbon fiber, and carbon nanotube. It is done. These can be used alone or in combination of two or more.

  The catalyst material supported on the carbon particles is not particularly limited as long as it causes a fuel cell reaction in the fuel electrode or air electrode of the fuel cell. For example, platinum, a platinum alloy, a platinum compound, etc. are mentioned. Examples of the platinum alloy include an alloy of platinum and at least one metal selected from the group consisting of ruthenium, palladium, nickel, molybdenum, iridium, iron and the like. Generally, the catalyst material when used as the air electrode catalyst layer is platinum, and the catalyst material when used as the fuel electrode catalyst layer is the alloy described above.

  The content of the catalyst-supporting carbon particles in the catalyst layer is usually about 10 to 90% by weight, preferably about 40 to 80% by weight.

Hydrogen ion conductive polymer electrolyte The hydrogen ion conductive polymer electrolyte is not limited, and a known or commercially available one can be used. Examples thereof include perfluorosulfonic acid-based fluorine ion exchange resins. Further, by introducing a fluorine atom having a high electronegativity, it is chemically very stable, the degree of sulfonic acid group dissociation is high, and high hydrogen ion conductivity can be realized. Specific examples of such a hydrogen ion conductive polymer electrolyte include, for example, “Nafion” manufactured by DuPont, “Flemion” manufactured by Asahi Glass Co., Ltd., “Aciplex” manufactured by Asahi Kasei Co., Ltd., and Gore. “Gore Select” manufactured by the company can be used.

  The content of the electrolyte in the catalyst layer is usually about 10 to 90% by weight, preferably about 20 to 60% by weight.

Aggregate The aggregate of the present invention contains catalyst-supporting carbon particles and a hydrogen ion conductive polymer electrolyte, and preferably substantially comprises catalyst support carbon particles and a hydrogen ion conductive polymer electrolyte. Specifically, the aggregate has a structure in which a hydrogen ion conductive polymer electrolyte is formed (or partially covered) on the surface of an aggregate in which a plurality of catalyst-carrying carbon particles are aggregated (aggregated). A conceptual diagram of the aggregate of the present invention is shown in FIG.

  Here, the catalyst-supporting carbon particles and the hydrogen ion conductive electrolyte serve as a conduction path for electrons and hydrogen ions, respectively. Since it is required to express high battery performance to efficiently transport electrons and hydrogen ions generated and consumed by electrode reaction, a paste composition containing catalyst-supporting carbon particles and a hydrogen ion conductive electrolyte If the dispersion of both is insufficient or excessive in the agitation, the conduction path of electrons and hydrogen ions is cut off and cannot be effectively used for battery performance.

  The average particle size of the aggregate of the present invention is not limited, but is preferably about 50 to 200 nm, and more preferably about 100 to 150 nm. By setting it as this range, while improving electroconductivity, since catalyst activity can be exhibited efficiently, electric power generation efficiency improves.

  In addition, the average particle diameter of the aggregate of the present invention is the case where 100 arbitrarily selected aggregates are observed with a scanning electron microscope (SEM) (magnification of about 30000 times) and the particle diameters of the aggregates are measured. The average value of

Catalyst layer The catalyst layer of this invention is comprised from the said aggregate. That is, the catalyst layer of the present invention is formed by aggregating a plurality of aggregates substantially including catalyst-carrying carbon particles and hydrogen ion conductive polymer electrolyte.

  In particular, the catalyst layer of the present invention has a porosity of 4 to 15% occupied by voids having a pore diameter of 10 nm to 500 nm, and a porosity of 7 to 25% occupied by voids having a pore diameter of 1 μm to 50 μm. Features. By having such a structure, the catalyst layer of the present invention has good gas diffusibility and reactivity, and can exhibit excellent current-voltage characteristics and thus excellent battery performance.

  The void ratio occupied by voids having a pore diameter of 10 nm to 500 nm, that is, the total void ratio of voids having a pore diameter in the range of 10 nm to 500 nm is about 4 to 15%, preferably 5 to 10%. %.

  The void ratio occupied by voids having a pore diameter of 1 μm to 50 μm, that is, the total void ratio of pores having a pore diameter in the range of 1 μm to 50 μm is about 7 to 25%, preferably 10 to 20% with respect to the entire catalyst layer. %, More preferably about 11 to 18%.

  In the present invention, the porosity of the pores having the above pore diameter is measured by a mercury porosimeter (manufactured by Shimadzu Corporation, “AutoPore 9500”).

The content of platinum in the catalyst layer is not limited and may be usually 0.1mg ^/ cm ² ~1.3mg ^/ cm 2 approximately. Thereby, an even higher power density can be achieved.

  The surface shape of the catalyst layer of the present invention is preferably about 1.5 μm to 3.0 μm, more preferably about 1.8 μm to 2.5 μm, when the line roughness is in the range of 1000 μm. By setting this range, more excellent current-voltage characteristics can be exhibited. The line roughness in the present invention is measured using a laser displacement meter (“LT-9010M + KS-1100”, manufactured by Keyence).

  The surface roughness of the catalyst layer is preferably about 0.2 μm to 1.0 μm, more preferably about 0.4 μm to 0.8 μm in the range of 50 μm × 50 μm. The surface roughness of the present invention is measured using a laser microscope (“VK-8500”, manufactured by Keyence).

  The thickness of the catalyst layer is not limited, but is usually about 5 to 200 μm, preferably about 10 to 150 μm.

  In addition, the catalyst layer may contain a third component to the extent that the effects of the present invention are not impaired, in addition to the aggregate.

Catalyst Layer Transfer Sheet The catalyst layer transfer sheet of the present invention is formed by laminating the catalyst layer on a transfer substrate.

  The transfer substrate is not particularly limited. For example, polyimide, polyethylene terephthalate, polyparabanic acid aramid, polyamide (nylon, etc.), polysulfone, polyethersulfone, polyphenylene sulfide, polyether ether ketone, polyetherimide, polyarylate, polyethylene Examples thereof include polymer films such as naphthalate and polypropylene. In addition, ethylene tetrafluoroethylene copolymer (ETFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), polytetrafluoroethylene (PTFE), etc. It is also possible to use a heat-resistant fluororesin. Further, the base material may be paper such as art paper, coated paper, light coated paper, and other non-coated paper such as notebook paper and copy paper, in addition to the polymer film. Among these, an inexpensive and easily available polymer film is preferable, and polyethylene terephthalate or the like is more preferable.

  The thickness of the transfer substrate is usually about 6 μm to 100 μm, preferably about 10 μm to 60 μm, from the viewpoints of handleability and economy.

  Further, a release layer may be laminated on the transfer substrate. Examples of the release layer include those composed of known waxes and plastic films coated with known fluororesins.

Electrolyte Membrane The electrolyte membrane used in the present invention is not limited as long as it is hydrogen ion conductive, and a known or commercially available membrane can be used. Specific examples of the electrolyte membrane include “Nafion” membrane manufactured by DuPont, “Flemion” membrane manufactured by Asahi Glass Co., Ltd., “Aciplex” membrane manufactured by Asahi Kasei Co., Ltd., and “Gore Select” manufactured by Gore. Examples include membranes. The thickness of the electrolyte membrane is usually about 20 to 250 μm, preferably about 20 to 80 μm.

Production Method The catalyst layer of the present invention is, for example, a catalyst layer forming paste composition obtained by mixing (1) catalyst-supporting carbon particles, (2) a hydrogen ion conductive polymer electrolyte, and (3) a viscosity adjusting solvent. It can be produced by applying an object (catalyst ink) to a transfer substrate and drying.

  The catalyst-supporting carbon particles, the hydrogen ion conductive polymer electrolyte, and the transfer substrate are as described above.

  Examples of the solvent include various alcohols, various ethers, various dialkyl sulfoxides, water, or a mixture thereof. Examples of the alcohol include monohydric alcohols having 1 to 4 carbon atoms such as methanol, ethanol, n-propanol, isopropanol, n-butanol, 2-butanol, isobutanol, and t-butanol, propylene glycol, ethylene glycol, diethylene glycol, Examples include polyhydric alcohols such as glycerin. These solvents may be used alone or in a combination of two or more.

  The proportion of the above components (1) to (3) contained in the catalyst layer forming paste composition of the present invention is not limited and can be appropriately selected within a wide range.

  For example, the component (2) is 0.1 to 5 parts by weight (preferably 0.15 to 3 parts by weight) and the component (3) is 5 to 50 parts by weight with respect to 1 part by weight of the catalyst-supported carbon particles of (1). About 10 parts by weight (preferably 10 to 25 parts by weight) should be contained, with the remainder being water. The ratio of water is usually from 10 to 10 times the weight of the catalyst-supporting carbon particles.

  The catalyst layer forming paste composition is produced by mixing the components (1) to (3). The order of mixing the components (1) to (3) is not particularly limited. For example, the paste composition for forming a catalyst layer can be prepared by mixing the component (1), the component (2), and the component (3) sequentially or simultaneously to disperse the catalyst-supporting carbon particles.

  In particular, in the present invention, it is important that the time required for dispersion (stirring time) is significantly longer than usual in the dispersion process. Thus, a desired catalyst layer can be obtained by applying the paste composition obtained by extending the dispersion time. The dispersion time is appropriately selected depending on the disperser (stirrer), the dispersion method, and the like, but is usually 10 minutes or longer, preferably about 35 to 460 minutes, more preferably about 50 to 450 minutes.

  The dispersion method may be carried out according to a conventional method, and examples thereof include a method of stirring the paste composition with a magnetic stirrer, a method of ultrasonically vibrating, a method of using these methods in combination. In the present invention, a method of stirring with a magnetic stirrer without performing ultrasonic vibration is particularly preferable.

In the present invention, in particular, the viscosity of the paste composition after dispersion is preferably 0.05 to 10 Pa · S (particularly 0.1 to 8 Pa · S) when the shear rate is in the range of 10 to 10,000 S ^−1. . More specifically, the viscosity is about ¹ to 10 Pa · S when the shear rate is 10 S ⁻¹ , and the viscosity is about 0.05 to 0.1 Pa · S when the shear rate is 10000 S ^−1. Preferably there is. More preferably, the viscosity is about ¹ to 8 Pa · S when the shear rate is 10 S ⁻¹ , and the viscosity is about 0.1 to 0.5 Pa · S when the shear rate is 10000 S ^−1. . The viscosity of the present invention is measured with a stress-controlled viscometer (“SR-5”, manufactured by Pheometric Scientific) at 25 ° C.

  The coating method of the paste composition is not particularly limited, and examples thereof include blade coaters, knife coaters, bar coaters, sprayers, dip coaters, spin coaters, roll coaters, die coaters, curtain coaters, screen printing, and the like. General methods can be applied.

  After applying such a paste composition, the catalyst layer is formed by drying. The drying method may be either heat drying or vacuum drying. In the case of employing heat drying, the drying temperature is usually about 40 to 100 ° C., preferably about 60 to 80 ° C., and the drying time is appropriately selected according to the drying temperature and the like, but usually 5 minutes About 2 hours, preferably about 30 minutes to 1 hour. When vacuum drying is employed, the drying pressure is 30 to 74 hPa, preferably about 40 to 57 hPa, and the drying time is appropriately selected according to the drying pressure and the like, but is usually about 10 minutes to 180 minutes, preferably What is necessary is just about 30 minutes-150 minutes.

  The catalyst layer transfer sheet in which the catalyst layer of the present invention is formed on the transfer substrate is transferred to both surfaces or one surface of the electrolyte membrane, so that the catalyst layers are laminated on both surfaces or one surface of the electrolyte membrane. A layer-electrolyte membrane laminate can be obtained.

  The pressure level at the time of transfer is usually about 0.5 to 20 MPa, preferably about 1 to 10 MPa, more preferably about 1 to 5 MPa in order to avoid transfer failure. In addition, it is preferable to heat the pressure surface during the pressurization in order to avoid transfer defects. The heating temperature is usually about 80 to 200 ° C., preferably about 135 to 150 ° C., in order to avoid breakage or modification of the electrolyte membrane.

  By sequentially laminating a known electrode substrate (for example, carbon paper, carbon cloth, etc.) and a separator on both sides of the obtained catalyst layer-electrolyte membrane laminate, the solid polymer fuel cell of the present invention is obtained. .

  According to the catalyst layer of the present invention, it is possible to produce a polymer electrolyte fuel cell that can exhibit excellent current-voltage characteristics, and thus excellent battery performance.

  Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. The present invention is not limited to the following examples.

  In addition, the surface roughness and line roughness measured by the Example and the comparative example are measured with the following measuring methods.

Method for measuring surface roughness After a catalyst layer is attached to a glass substrate via a double-sided tape, a laser-free microscope ("LT-9010M + KS-100", manufactured by Keyence) is used to select a crack-free portion, and the catalyst The surface height was measured with an accuracy of 0.02 μm at intervals of about 0.15 μm in the analysis region of the layer surface 50 μm × 50 μm. The number of measurement locations was three, and measurement was performed three times at each location, and the average value of the total surface height of nine times was defined as the surface roughness in the present invention.

Method for Measuring Line Roughness After a catalyst layer is attached to a glass substrate via a double-sided tape, the surface of the catalyst layer is spread over 2 μm over 1000 μm using a laser microscope (“VK-8500”, manufactured by Keyence). A total of 500 surface heights were measured with an accuracy of 0.01 μm. The number of measurement points was three for each catalyst layer from upstream to downstream in the coating direction. The measurement was performed three times at each location, and the average value of the total line roughness of 9 times was defined as the line roughness in this example. At the time of measurement, in order to correct waviness caused by the glass substrate and the double-sided tape, a cut-off process was performed every 80 μm.

Average particle sizes of agglomerates of aggregates, the surface of the catalyst layer, a scanning electron microscope (SEM) (JEOL Ltd., FE-SEM168F) was determined from SEM images were taken using. In addition, the average value when the particle size of 100 aggregates arbitrarily selected from the SEM image (magnification of about 30000 times) was measured was defined as the average particle size.

Active surface area per unit weight of platinum The active surface area per unit weight of platinum is the activity calculated from the amount of electricity absorbed and desorbed from hydrogen obtained from the CV curve measured using an electrochemical analyzer (model 611A / 680, manufactured by ALS). The surface area was obtained by dividing by the weight of platinum contained in the catalyst membrane.

Example 1
Platinum supported carbon particles (Pt: 40% by weight) (manufactured by Johnson Matthey) 0.8 parts by weight and 5% by weight electrolyte solution (manufactured by Aldrich, 5 wt% Nafion solution, product number 274704, water: 1-propanol: 4 parts by weight of 2-propanol = 1: 1.5: 2 (weight ratio) was added to 1.5 parts by weight of isopropanol, and stirring with a stirrer was performed for 240 minutes to prepare a paste composition for forming a catalyst layer. The viscosity of the prepared paste composition was 0.075 to 10 Pa · S when the shear rate was in the range of 10 to 10,000 S ⁻¹ .

  On one side of a transfer substrate (Teflon (registered trademark) sheet, thickness 50 μm, manufactured by Nichias Co., Ltd.), the paste composition for forming a catalyst layer is 100 μm before drying with a blade coater. Applied. The film thickness after drying was 6 μm. The drying conditions for vacuum drying were drying at 57 hPa for 30 minutes, and then drying under reduced pressure until the pressure stabilized.

The porosity of the obtained catalyst layer of Example 1 was measured using a mercury porosimeter (manufactured by Shimadzu Corporation, “AutoPore 9500”). The void ratio occupied by voids having a pore diameter of 10 nm to 500 nm was 8.0%, and the void ratio occupied by voids having a pore diameter of 1 μm to 50 μm was 8.0%. The surface roughness was 0.5 μm, the line roughness was 2.1 μm, the average particle size of the aggregate was about 120 μm, and the active surface area per unit weight of platinum was 571 cm ² -Pt / mg-Pt. In addition, in Example 1, SEM observed when measuring the average particle diameter of an aggregate is shown in FIG.

Example 2
A paste composition for forming a catalyst layer was prepared in the same manner as in Example 1 except that the stirring time was 120 minutes. The viscosity of the prepared paste composition was 0.075 to 10 Pa · S when the shear rate was in the range of 10 to 10,000 S ⁻¹ .

Next, a catalyst layer was formed in the same manner as in Example 1 except that the prepared paste composition was used. In the obtained catalyst layer of Example 2, the porosity of pores having a pore diameter of 10 nm to 500 nm was 9.3%, and the porosity of pores having a pore diameter of 1 μm to 50 μm was 14.0%. Further, the surface roughness was 0.5 μm, the line roughness was 2.2 μm, the average particle size of the aggregate was about 110 μm, and the active surface area per unit weight of platinum was 514 cm ² -Pt / mg-Pt. In addition, in Example 2, SEM observed when measuring the average particle diameter of an aggregate is shown in FIG.

Example 3
A paste composition for forming a catalyst layer was prepared in the same manner as in Example 1 except that the stirring time was 60 minutes. The viscosity of the prepared paste composition was 0.075 to 5 Pa · S when the shear rate was 10 to 10,000 S ⁻¹ .

Next, a catalyst layer was formed in the same manner as in Example 1 except that the prepared paste composition was used. In the obtained catalyst layer of Example 3, the porosity of pores with a pore diameter of 10 nm to 500 nm was 10%, and the porosity of pores with a pore diameter of 1 μm to 50 μm was 23%. Further, the surface roughness was 0.5 μm, the line roughness was 2.0 μm, the average particle size of the aggregate was about 120 μm, and the active surface area per unit weight of platinum was 501 cm ² -Pt / mg-Pt. In addition, in Example 3, SEM observed when measuring the average particle diameter of an aggregate is shown in FIG.

Comparative Example 1
A paste composition for forming a catalyst layer was prepared in the same manner as in Example 1 except that the stirring time was 12 hours. The viscosity of the prepared paste composition was 0.075 to 5 Pa · S when the shear rate was 10 to 10,000 S ⁻¹ .

Next, a catalyst layer was formed in the same manner as in Example 1 except that the prepared paste composition was used. In the obtained catalyst layer of Comparative Example 1, the porosity of pores having a pore diameter of 10 nm to 500 nm was 9.4%, and the porosity of pores having a pore diameter of 1 μm to 50 μm was 6.1%. The surface roughness was 0.5 μm, the line roughness was 2.0 μm, the average particle size of the aggregate was about 110 μm, and the active surface area per unit weight of platinum was 492 cm ² -Pt / mg-Pt. In addition, in Comparative Example 1, SEM observed when measuring the average particle diameter of the aggregate is shown in FIG.

Comparative Example 2
A paste composition for forming a catalyst layer was prepared in the same manner as in Example 1 except that the stirring time was 30 minutes. The viscosity of the prepared paste composition was 0.075 to 5 Pa · S when the shear rate was 10 to 10,000 S ⁻¹ .

Next, a catalyst layer was formed in the same manner as in Example 1 except that the prepared paste composition was used. In the obtained catalyst layer of Comparative Example 2, the porosity of pores having a pore diameter of 10 nm to 500 nm was 10%, and the porosity of pores having a pore diameter of 1 μm to 50 μm was 30%. The surface roughness was 0.5 μm, the line roughness was 2.0 μm, the average particle size of the aggregate was about 120 μm, and the active surface area per unit weight of platinum was 465 cm ² -Pt / mg-Pt. In addition, in Comparative Example 2, the SEM observed when measuring the average particle size of the aggregate is shown in FIG.

Comparative Example 3
A paste composition for forming a catalyst layer was prepared in the same manner as in Example 1 except that the stirring time was 24 hours. The viscosity of the prepared paste composition was 0.075 to 10 Pa · S when the shear rate was in the range of 10 to 10,000 S ⁻¹ .

Next, a catalyst layer was formed in the same manner as in Example 1 except that the prepared paste composition was used. In the catalyst layer of Comparative Example 3, the porosity of pores having a pore diameter of 10 nm to 500 nm was 8.9%, and the porosity of pores having a pore diameter of 1 μm to 50 μm was 5.6%. The surface roughness was 0.5 μm, the line roughness was 2.0 μm, the average particle size of the aggregate was about 110 μm, and the active surface area per unit weight of platinum was 486 cm ² -Pt / mg-Pt. In addition, in Comparative Example 3, SEM observed when measuring the average particle diameter of the aggregate is shown in FIG.

Comparative Example 4
A paste composition for forming a catalyst layer was prepared in the same manner as in Example 1 except that the stirring time was 8 hours. The viscosity of the prepared paste composition was 0.075 to 10 Pa · S when the shear rate was in the range of 10 to 10,000 S ⁻¹ .

Next, a catalyst layer was formed in the same manner as in Example 1 except that the prepared paste composition was used. In the obtained catalyst layer of Comparative Example 1, the porosity of pores having a pore diameter of 10 nm to 500 nm was 8.3%, and the porosity of pores having a pore diameter of 1 μm to 50 μm was 6.0%. Further, the surface roughness was 0.5 μm, the line roughness was 2.2 μm, the average particle size of the aggregate was about 110 μm, and the active surface area per unit weight of platinum was 469 cm ² -Pt / mg-Pt. In Comparative Example 4, the SEM observed when measuring the average particle size of the aggregate is shown in FIG.

Test Examples The catalyst transfer sheets produced in Examples 1 to 3 and Comparative Examples 1 to 4 were transferred to both sides of a solid polymer electrolyte membrane (“Nafion 112” manufactured by Dupont), and then an electrode substrate (carbon paper) and The polymer electrolyte fuel cells of Examples 1 to 3 and Comparative Examples 1 to 4 were manufactured by sequentially sandwiching the separator. The current-voltage characteristics were measured for each of these fuel cells. The measurement results are shown in FIG.

FIG. 1 is a conceptual diagram of aggregates constituting the catalyst layer of the present invention. FIG. 2 is an SEM photograph of the catalyst layer of Example 1. FIG. 3 is a SEM photograph of the catalyst layer of Example 2. FIG. 4 is a SEM photograph of the catalyst layer of Example 3. FIG. 5 is an SEM photograph of the catalyst layer of Comparative Example 1. FIG. 6 is an SEM photograph of the catalyst layer of Comparative Example 2. FIG. 7 is an SEM photograph of the catalyst layer of Comparative Example 3. FIG. 8 is an SEM photograph of the catalyst layer of Comparative Example 4. FIG. 9 is a graph showing the relationship between the current and voltage of the fuel cells obtained in Examples 1-3 and Comparative Examples 1-4.

Claims (6)

(1) Consists of an agglomerate containing catalyst-supporting carbon particles and a hydrogen ion conductive polymer electrolyte,
(2) The void ratio occupied by voids having a pore diameter of 10 nm to 500 nm is 8 to 10 %,
(3) The void ratio occupied by voids having a pore diameter of 1 μm to 50 μm is 7 to 25%.
Catalyst layer for polymer electrolyte fuel cell. 2. The catalyst layer according to claim 1, wherein an average particle diameter of the aggregate containing the catalyst-supporting carbon particles and the hydrogen ion conductive polymer electrolyte is 50 to 200 nm. The catalyst layer according to claim 1 or 2 active surface area per unit weight of the catalyst in the catalyst-carrying carbon particles are 450~600cm ² / mg. A catalyst layer transfer sheet, wherein the catalyst layer according to claim 1 is formed on a transfer substrate. A catalyst layer-electrolyte membrane laminate obtained by transferring the catalyst layer transfer sheet according to claim 4 to an electrolyte membrane. A polymer electrolyte fuel cell comprising the catalyst layer-electrolyte membrane laminate according to claim 5.

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