JP2013191521A - Apparatus of manufacturing membrane electrode assembly for solid polymer fuel cell, and membrane electrode assembly - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an apparatus of manufacturing a solid polymer fuel cell in which a catalyst layer has a uniform thickness, and swelling of the membrane is suppressed when forming a catalyst layer by coating the surface of an electrolyte membrane directly with a catalyst ink by means of a die coater, and then drying.SOLUTION: The apparatus of manufacturing a membrane electrode assembly for solid polymer fuel cell includes means for forming beads by supplying a catalyst ink containing at least a polymer material and a solvent onto one surface of an electrolyte membrane, means for coating one surface of the electrolyte membrane with the catalyst ink, by moving the electrolyte membrane placed on a suction plate by means of a conveyance roll and then sweeping the beads, and means for removing a solvent in the catalyst ink by volatilization, by heating the position of the electrolyte membrane corresponding to the beads, the part of the catalyst ink immediately after coating, and the remaining part of the catalyst ink after coating, from the other side of the electrolyte membrane.

Description

  The present invention relates to an apparatus for manufacturing a membrane electrode assembly in a polymer electrolyte fuel cell.

The power generation system of a fuel cell is a system in which chemical energy of a fuel is converted into electrical energy and extracted by causing an electrochemical reaction between a fuel such as hydrogen and an oxidant such as air. This power generation method is expected to be used as a new energy application because of its advantages such as high power generation efficiency, excellent quietness, NOx and SOx that cause air pollution, and low CO ₂ emissions that cause global warming. Has been. Examples of the application of this fuel cell include a long-time power supply for portable electric devices, a stationary power generation hot water supply machine for cogeneration, a fuel cell vehicle, and the like, which have various uses and scales.

  The types of fuel cells are classified into solid polymer type, phosphoric acid type, molten carbonate type, solid oxide type, alkaline type, etc. depending on the electrolyte used. Is also different.

  The one using a cation exchange membrane as an electrolyte is called a polymer electrolyte fuel cell, and can operate at a relatively low temperature among fuel cells, and the internal resistance can be reduced by reducing the thickness of the electrolyte membrane. Therefore, high output and compactness are possible, and it is considered promising for use in in-vehicle power supplies, household stationary power supplies, and the like.

  A polymer electrolyte fuel cell has a structure in which a pair of electrocatalyst layers are arranged on both sides of an electrolyte membrane called a membrane-electrode-assembly (MEA), and one electrode (anode side) is hydrogenated. Sandwiched between a separator plate having a gas flow path for supplying a fuel gas containing oxygen and a separator plate having a gas flow path for supplying an oxidant gas containing oxygen to the other electrode (cathode side) Battery. A battery sandwiched between the pair of separator plates is called a single battery cell.

  A polymer electrolyte fuel cell is used by stacking a plurality of unit cells for the purpose of increasing power density and making the entire fuel cell compact. The number of sheets to be stacked varies depending on the required electric power. For portable power sources of general portable electric devices, several to about 10 sheets, for stationary electric and hot water supply machines for cogeneration, about 60 to 90 sheets, and for automobile applications, 250 to About 400 sheets. In order to increase the output, it is necessary to increase the number of stacks, and the cost of the unit cell greatly affects the cost of the entire fuel cell. From the viewpoint of process cost, a membrane electrode assembly structure with a small number of parts and easy assembly is desired.

  In recent years, when manufacturing a membrane electrode assembly, a method of forming a catalyst layer by directly applying a catalyst ink to an electrolyte membrane has been attempted. This method is attracting attention as an ideal method because it does not require any auxiliary material and can reduce the process cost, and the performance is improved due to the high adhesion between the electrolyte membrane and the catalyst layer.

  However, there is a problem that the electrolyte membrane swells as soon as it comes into contact with the solvent of the catalyst ink. As a method for solving this problem, there has been proposed a method of drying and removing the solvent at the same time as applying the catalyst ink by installing an electrolyte membrane on the heating adsorption plate and performing backside heating (for example, Patent Document 1). 2). As a method for applying the catalyst ink, a spray method is employed for the purpose of promoting the evaporation of the solvent.

JP 2003-100314 A JP 2006-344517 A

  However, in the techniques described in Patent Documents 1 and 2, when a method using a gravure printing method, a brush coating method, a die coating method, a doctor blade, or the like is applied as a coating method, the backside heating is performed. It dries in the middle of coating, and the amount of solvent in the catalyst ink decreases with coating. As a result, the catalyst layer formed on the electrolyte membrane has a non-uniform thickness. For example, when coating is performed by a die coating method, a catalyst ink liquid reservoir called a bead serving as a catalyst ink supply unit dries during coating, and the amount of solvent in the catalyst ink decreases with coating. . Since the wet film thickness at the time of coating is constant, as a result, the catalyst layer thickness gradually increases toward the coating end portion.

  The present invention has been accomplished in consideration of the above problems, and a manufacturing apparatus that suppresses swelling of the electrolyte membrane and makes the thickness of the catalyst layer uniform when the catalyst ink is directly applied to the electrolyte membrane by the blade method. The purpose is to provide.

  The apparatus for producing a membrane electrode assembly for a polymer electrolyte fuel cell according to the present invention comprises a bead forming means for supplying a catalyst ink containing at least a polymer material and a solvent onto one surface of an electrolyte membrane to form a bead. The electrolyte membrane is held, and the held electrolyte membrane is transferred in a predetermined transfer direction, so that the held electrolyte membrane is moved relative to the bead forming means, and the catalyst ink is placed on one surface of the electrolyte membrane. The transporting means for coating, the part immediately after coating of the catalyst ink positioned on the transport direction side from the bead formed on the electrolyte membrane, and the coating of the catalyst ink positioned on the transporting direction side from the part immediately after coating And a heating means for heating the portion from the other side of the electrolyte membrane to volatilize and remove the solvent in the catalyst ink.

  The heating means is arranged on the other surface side of the electrolyte membrane and includes a plurality of heating zones set at different temperatures.

  The heating zone is disposed at a position corresponding to the bead formed on the electrolyte membrane, a position corresponding to a portion immediately after the application of the catalyst ink, and a position on the transport direction side from the portion immediately after the application of the catalyst ink. The heating zone disposed at a position corresponding to the bead formed on the electrolyte membrane is set to a temperature at which the bead does not dry and is disposed at a position corresponding to the portion immediately after the application of the catalyst ink. Is set in the vicinity of the volatilization temperature of the solvent in the catalyst ink, and the heating zone arranged at the position in the transport direction side immediately after the coating of the catalyst ink is set to be equal to or higher than the volatilization temperature of the solvent in the catalyst ink. It is characterized by.

  The width of the heating zone in the transport direction is the same length as the width of the bead in the same direction.

  The membrane / electrode assembly according to the present invention is a membrane / electrode assembly produced by the production apparatus described above.

  According to the production apparatus of the present invention, since the catalyst ink is applied and heated and dried at the same time, the solvent in the catalyst ink evaporates at the same time as touching the electrolyte membrane, and the swelling of the electrolyte membrane can be suppressed. Since the same amount of catalyst can always be applied to the electrolyte membrane, the catalyst layer thickness is uniform.

Schematic diagram of a conventional manufacturing apparatus for membrane electrode assemblies by coating with backside heating drying Schematic schematic diagram of an apparatus for producing a membrane / electrode assembly by coating with backside heating drying of the present invention Sectional drawing of the membrane electrode assembly produced with the manufacturing apparatus of this invention The top view of the membrane electrode assembly produced with the manufacturing apparatus of this invention

Hereinafter, the manufacturing apparatus of the membrane electrode assembly in the polymer electrolyte fuel cell concerning embodiment of this invention is demonstrated in detail using drawing.

  FIG. 1 is a schematic diagram showing a conventional apparatus for producing a membrane / electrode assembly by coating with backside heating and drying. The membrane / electrode assembly manufacturing apparatus shown in FIG. 1 has an electrolyte membrane 1 adsorbed and fixed on the upper surface, a transport adsorbing device 7 for conveying the adsorbed and fixed electrolyte membrane 1, and a catalyst ink adjusted in advance to the electrolyte membrane 1. The head 12 to be coated and one heating zone 15 which is disposed on the lower surface side of the transport adsorption device 7 and set to a temperature equal to or higher than the solvent volatilization temperature of the catalyst ink are provided. The cathode catalyst layer 2 is formed by applying catalyst ink to the electrolyte membrane 1. In the apparatus for manufacturing a membrane electrode assembly shown in FIG. 1, since the entire electrolyte membrane 1 is uniformly heated by the heating zone 15, it is included in the bead 13 portion while sweeping the bead 13 of catalyst ink. Since the solid component concentration gradually increases, the thickness of the cathode catalyst layer 2 after the solvent removal becomes nonuniform.

FIG. 2 is a schematic diagram of an apparatus for producing a membrane / electrode assembly by coating with backside heating according to the present invention. As shown in FIG. 2, the apparatus for manufacturing a membrane / electrode assembly according to an embodiment of the present invention mainly includes a transport adsorption device 7 that adsorbs and fixes an electrolyte membrane 1 on the upper surface and transports the adsorbed electrolyte membrane 1. The head 12 for applying the catalyst ink prepared in advance to the electrolyte membrane 1 and the heating zones 8, 9, and 10 that are arranged on the lower surface side of the transport adsorption device 7 and set to different temperatures are provided. The membrane electrode assembly manufacturing apparatus shown in FIG. 2 includes heating zones 8, 9, and 10 set at different temperatures instead of the heating zone 15 of the membrane electrode assembly manufacturing apparatus shown in FIG. Is different. 2 forms the cathode catalyst layer 2 by applying a catalyst ink to the electrolyte membrane 1.

  The transport adsorption device 7 can adopt any mechanism as long as at least a portion where the electrolyte membrane 1 is installed can be adsorbed and the adsorbed electrolyte membrane 1 can be transported. For example, a mechanism that performs suction by sucking a transportable porous plate with a pump can be used. In addition, you may take the structure which installs a porous adsorption | suction plate on a general belt conveyor.

  The electrolyte membrane 1 used in the present invention may be one generally used for polymer electrolyte fuel cells. For example, a fluorine-based electrolyte membrane or a hydrocarbon electrolyte membrane can be suitably used, and a fluorine-based electrolyte membrane is particularly desirable.

The head 12 may be a die head that is generally used during coating, such as die coating. As shown in FIG. 2, the head 12 is fixed at a predetermined position so that the longitudinal direction thereof coincides with the width direction of the electrolyte membrane 1 (the direction orthogonal to the transport direction), and the head 12 extends in the width direction of the electrolyte membrane 1. The catalyst ink is applied at the same time in the extending line shape. The head 12 can continuously form an ink line in the width direction of the electrolyte membrane with respect to the electrolyte membrane 1 conveyed by the conveyance adsorption device 7, thereby opening the mask 11 disposed on the electrolyte membrane 1. The catalyst ink can be applied to the part. In the case of coating by the blade method, the catalyst ink may be stored in advance on the upper surface portion of the mask 11 and swept by the blade to form the ink lines continuously in the same manner as the die coating.

  The catalyst ink applied from the head 12 may be one generally used for solid polymer fuel cells. For example, a conductive material such as carbon black in which fine particles of platinum or an alloy of platinum and another metal (for example, Ru, Rh, Mo, Cr, Co, Fe, etc.) (the average particle diameter is preferably 10 nm or less) is supported on the surface. The carbonaceous fine particles (average particle diameter: about 20 to 100 nm) and a polymer solution such as a perfluorosulfonic acid resin solution are uniformly mixed in an appropriate solvent (ethanol or the like).

  The heating zones 8, 9, and 10 installed on the lower surface side of the conveyance suction device 7 are set to different temperatures. Specifically, the heating zone 8 installed at a position corresponding to the bead 13 is at a normal temperature, adjacent to the heating zone 8 and in the transport direction of the electrolyte membrane 1 and corresponding to a portion immediately after application of the catalyst ink. The heating zone 9 installed in the heating zone 10 is installed at a position corresponding to the catalyst layer portion in the transport direction of the electrolyte membrane 1 adjacent to the heating zone 9 at the volatilization temperature of the solvent in the catalyst ink. Is set above the volatilization temperature of the solvent of the catalyst ink.

  Drying of the bead 13 can be prevented by setting the temperature of the heating zone 8 installed at a position corresponding to the bead 13 to a room temperature of 20 ° C. to 25 ° C. Moreover, since the solid content concentration of the bead 13 is kept constant by preventing the bead 13 from drying, the thickness of the cathode catalyst layer 2 after removing the solvent becomes uniform. Further, in order to prevent the beads 13 from being dried and to keep the solid concentration constant, it is desirable that the width of the heating band 8 in the transport direction is the same as the width of the beads 13 in the transport direction. In this case, the heating zone 8 is arranged at a position overlapping the bead 13. When the width of the heating zone 8 is smaller than the width of the bead 13, the adjacent heating zone 9 set to a high temperature is installed on the back surface of the bead 13, and the bead 13 is dried. On the other hand, when the width of the heating zone 8 is larger than the width of the bead 13, the heating zone 8 at room temperature is installed on the back surface of the catalyst layer portion immediately after coating adjacent to the bead portion 13, and the catalyst layer is immediately removed. It becomes impossible to dry. The width of the heating zone 8 and the width of the bead 13 do not need to be exactly the same, and there may be an error of about ± 1.0 mm. Further, in order to keep the solid content concentration constant, it is desirable that the width of the heating zone 8 in the direction orthogonal to the conveyance direction is longer than the width of the bead 13 in the direction orthogonal to the conveyance direction.

  Further, the temperature of the heating zone 9 that is located adjacent to the heating zone 8 and in the transport direction of the electrolyte membrane 1 and corresponding to the portion immediately after the application of the catalyst ink is set to the volatilization temperature of the solvent in the catalyst ink. By setting, the solvent in the catalyst ink evaporates at the same time as touching the electrolyte membrane 1, and the swelling of the electrolyte membrane 1 can be suppressed. Furthermore, by setting the temperature of the heating zone 10 installed at a position corresponding to the cathode catalyst layer 2 portion adjacent to the heating zone 9 and in the transport direction of the electrolyte membrane 1 to be equal to or higher than the volatilization temperature of the solvent in the catalyst ink. The solvent in the cathode catalyst layer 2 can be removed stepwise. In addition, by providing the heating zones 9 and 10 set at different temperatures, the cathode catalyst layer 2 can be dried stepwise, so that it can be suitably used even when the solvent of the catalyst ink is a mixed solvent. can do. Further, in order to sufficiently dry the cathode catalyst layer 2, the width of the heating zones 9 and 10 in the direction perpendicular to the transport direction is longer than the width of the bead 13 in the direction perpendicular to the transport direction. desirable.

  The cathode catalyst layer 2 is formed on one surface of the electrolyte membrane 1 by the manufacturing apparatus described above. The anode electrode layer 3 is formed on the other surface of the electrolyte membrane 1 by applying the catalyst ink using the manufacturing apparatus shown in FIG. 2, thereby completing the membrane electrode assembly 14. The order of forming the cathode catalyst layer 2 and the anode catalyst layer 3 on the electrolyte membrane 1 may be arbitrary. In the above description, the heating zone 8 is used. However, the heating zone 8 may not be provided. A heating zone 9 may be installed at a position corresponding to a portion in the transport direction of the electrolyte membrane 1 adjacent to the bead 13 forming portion, and a heating zone 10 may be installed at a location in the transport direction of the electrolyte membrane 1 adjacent to the heating zone 9. It ’s fine.

  Below, the manufacturing apparatus of the polymer electrolyte fuel cell of this invention is demonstrated by a specific Example. In addition, the Example mentioned later is one Example of this invention, and this invention is not limited only to this Example. FIG. 3 shows a cross-sectional view of the membrane electrode assembly 14 produced in this example, and FIG. 4 shows a top view thereof.

A platinum-supporting carbon catalyst (trade name: TEC10E50E, manufactured by Tanaka Kikinzoku Kogyo Co., Ltd.) having a platinum-supporting amount of 50% and Nafion (registered trademark, manufactured by DuPont), which is a 20% by mass polymer electrolyte solution, have a mixing ratio of 1: 2 water-ethanol mixed solvent. Subsequently, a dispersion treatment was performed with a planetary ball mill to prepare a catalyst ink.

  A central portion of a two-layer film in which a polyethylene terephthalate film with a weak adhesive layer was bonded to the gasket layer was punched out to produce an annular two-layer mask 11. The opening size of the mask 11 is 50 mm square. Subsequently, the manufactured frame-shaped mask 11 was bonded to the electrolyte membrane. As the electrolyte membrane 1, Nafion 212 (registered trademark, manufactured by DuPont) was used.

  The electrolyte membrane 1 having the frame-shaped mask 11 bonded thereto was fixed on the transport adsorption device 7 and transported at a transport speed of 100 mm / sec. A heating zone 8 having a length of 10 mm set at a room temperature of 25 ° C. is installed on the back surface of the bead 13 forming portion, and a heating zone 9 having a length of 10 mm set at 120 ° C. is adjacent to the heating zone 8 and the electrolyte membrane 1. A heating zone 10 having a length of 10 mm set at 150 ° C. was placed adjacent to the heating zone 9 at a position in the conveyance direction of the electrolyte membrane 1.

The adjusted catalyst ink was applied from the head (die head) 12 and applied by a die coater. After the coating process and the backside heating drying process were repeated twice so that the amount of platinum supported was equivalent to the cathode catalyst layer (0.4 mg / cm ² ), the adsorption fixation was released. Subsequently, the polyethylene terephthalate film with a weak adhesive layer was peeled from the gasket layer to obtain an electrolyte membrane 1 in which the cathode catalyst layer 2 was formed on one side and the cathode side gasket layer 4 was disposed on the peripheral edge of the cathode catalyst layer 2. .

The electrolyte membrane 1 having the cathode catalyst layer 2 formed on one side is turned upside down, and the anode catalyst layer 3 is formed in the same manner on the surface opposite to the surface on which the cathode catalyst layer 2 is formed, and the anode catalyst layer is formed on both surfaces of the electrolyte membrane 1. 3 was formed, and a membrane electrode assembly 14 in which the anode side gasket layer 5 was arranged on the periphery of the anode catalyst layer 3 was obtained. The coating process using the die coater and the back surface heating and drying process were performed only once so that the amount of platinum supported was equivalent to the anode catalyst layer 3 (0.1 mg / cm ² ).

  When the thickness of the catalyst layer of the produced membrane electrode assembly 14 was measured, it was uniform on both the cathode side and the anode side.

  INDUSTRIAL APPLICABILITY The present invention can be suitably used for a polymer electrolyte fuel cell single cell or a stack in a polymer electrolyte fuel cell, particularly a fuel cell automobile or a household fuel cell.

DESCRIPTION OF SYMBOLS 1 Electrolyte membrane 2 Cathode catalyst layer 3 Anode catalyst layer 4 Cathode side gasket layer 5 Anode side gasket layer 7 Conveyance adsorption device 8 Heating zone (room temperature)
9 Heating zone (solvent volatilization temperature of catalyst ink)
10 Heating zone (above solvent evaporation temperature of catalyst ink)
11 Mask 12 Head 13 Bead 14 Membrane Electrode Assembly 15 Heating Zone (Conventional Device)

Claims (5)

An apparatus for producing a membrane electrode assembly for a polymer electrolyte fuel cell,
A bead forming means for supplying a catalyst ink containing at least a polymer material and a solvent onto one surface of the electrolyte membrane to form a bead;
The electrolyte membrane is retained, and the retained electrolyte membrane is transported in a predetermined transport direction, whereby the retained electrolyte membrane is moved relative to the bead forming means, and the catalyst ink is moved to the electrolyte membrane. Conveying means for coating the one side of
A portion immediately after application of the catalyst ink positioned on the transport direction side of the bead formed on the electrolyte membrane, and after application of the catalyst ink positioned on the transport direction side of a portion immediately after the coating And a heating means for volatilizing and removing the solvent in the catalyst ink by heating the portion from the other surface side of the electrolyte membrane.   2. The membrane electrode for a polymer electrolyte fuel cell according to claim 1, wherein the heating means includes a plurality of heating zones arranged on the other surface side of the electrolyte membrane and set at different temperatures. Bonded body manufacturing equipment. The heating zone includes a position corresponding to the bead formed on the electrolyte membrane, a position corresponding to a portion immediately after application of the catalyst ink, and a side in the transport direction from a portion immediately after application of the catalyst ink. It is arranged at the position of
The heating zone disposed at a position corresponding to the bead formed on the electrolyte membrane is set to a temperature at which the bead does not dry,
The heating zone disposed at a position corresponding to the portion immediately after the application of the catalyst ink is set near the volatilization temperature of the solvent in the catalyst ink,
The heating zone disposed at a position closer to the transport direction than a portion immediately after application of the catalyst ink is set to be equal to or higher than a volatilization temperature of a solvent of the catalyst ink. An apparatus for producing a membrane electrode assembly for a polymer electrolyte fuel cell.   4. The membrane electrode assembly for a polymer electrolyte fuel cell according to claim 2, wherein the width of the heating zone in the transport direction is the same length as the width of the bead in the same direction. 5. manufacturing device.   The membrane electrode assembly produced with the manufacturing apparatus in any one of Claims 1-4.

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