JP2018037367A - Membrane-electrode assembly, method for manufacturing the same, and solid polymer fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide: a membrane-electrode assembly which is high in the precision of the location of an electrode layer and a gasket; and a solid polymer fuel cell which can suppress the worsening of a performance owing to gas leak, and the degradation of progression of an electrolyte membrane.SOLUTION: A membrane-electrode assembly comprises: an anode electrode on one face of a polymer electrolyte membrane; a cathode electrode on the other face; and gaskets arranged to be adjacent to the anode and cathode electrodes respectively along outer peripheries thereof like a frame. Each gasket has, on at least part of a surface thereof, fine asperities arrayed periodically. The fine asperities are opposed to and in contact with the opposing faces of the polymer electrolyte membrane.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a membrane electrode assembly that is a laminate of a polymer electrolyte membrane and a catalyst layer used in manufacturing a membrane electrode assembly that is a constituent member of a polymer electrolyte fuel cell, a method for manufacturing the membrane electrode assembly, and The present invention relates to a polymer electrolyte fuel cell.

  A fuel cell is a power generation system that converts a chemical energy of a fuel into electric energy and extracts it by electrochemically reacting a fuel such as hydrogen with an oxidant such as air. This power generation method is expected as new energy because of its advantages such as high power generation efficiency, excellent quietness, NOx and SOx that cause air pollution, and low CO2 emissions that cause global warming. Yes. Examples of the application of this fuel cell include a long-time power supply for portable electric devices, a stationary 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 as a vehicle-mounted source or a household stationary power source.

  A polymer electrolyte fuel cell is a fuel gas containing hydrogen on one side of an electrode, in which a pair of electrode catalyst layers is arranged on both sides of an electrolyte membrane called a membrane electrode assembly (MEA). And is sandwiched between a pair of separator plates formed with a gas flow path for supplying an oxidant gas containing oxygen to the other of the electrodes. 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 stacks varies depending on the power required. For portable power sources of general portable electric devices, several to about 10 sheets, for cogeneration stationary electric and hot water supply machines, about 60 to 90 sheets, and for automobile applications, 250 sheets. From about 400 to 400. 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.

  As a method for producing a membrane-catalyst layer assembly composed of an electrode catalyst layer and an electrolyte membrane called CCM (Catalyst Coated Membrane), there is a method of applying a catalyst ink to a polymer electrolyte membrane with a support and drying. (Patent Document 1)

  However, in the method of Patent Document 1, as a result of blocking the polymer electrolyte membrane surface or internal pores and hindering the gas flow performance, the performance of the fuel cell using the obtained membrane electrode assembly may be deteriorated. .

  In addition, when the catalyst layer is formed on the electrolyte, the electrolyte is swollen and deformed by the solvent or liquid in the ink, making it difficult to maintain the shape, and it is not easy to adjust the film thickness and ensure uniformity. As a result, the membrane electrode assembly to be finally produced is likely to be deformed such as warpage and distortion, which leads to a problem of quality deterioration.

  As a method for avoiding the above drawbacks, a method is known in which a catalyst layer is transferred to an electrolyte membrane from a transfer sheet having a catalyst layer formed on a substrate (Patent Document 2). However, Patent Document 2 only describes that a catalyst layer whose film thickness is controlled by screen printing is formed and transferred to a polymer electrolyte membrane.

  When the catalyst layer is transferred from the transfer sheet to the electrolyte membrane, it is necessary to accurately align and stack the opposing anode electrode catalyst layer and cathode electrode catalyst layer. If not, there is a problem that performance degradation due to gas leakage or deterioration of the electrolyte membrane may occur.

  As a method of accurately aligning and stacking the catalyst layer for the anode electrode and the catalyst layer for the cathode electrode facing each other, a method of adjusting the coordinates mechanically by recognizing the position of the electrode catalyst layer with a camera, Methods using positioning pins are known. However, these methods do not provide sufficient accuracy, which is a cause of a decrease in yield.

JP 2003-257449 A Japanese Patent Laid-Open No. 10-64574

  The present invention has been made in view of the above circumstances, and is more accurate than the conventional method by shaping the gasket, which is a sealing material on the frame provided at the peripheral portion of the electrode catalyst layer. It is an object of the present invention to provide a membrane electrode assembly, a polymer electrolyte fuel cell, and a method for manufacturing the same.

As a means for solving the above problems, the first aspect of the present invention is:
A membrane electrode assembly comprising an anode electrode on one surface of a polymer electrolyte membrane and a cathode electrode on the other surface, and gaskets adjacent to each other along the outer periphery of the anode electrode and the cathode electrode,
At least a part of the surface of the gasket has fine irregularities arranged periodically,
The fine concavo-convex shape is a membrane electrode assembly characterized in that it is in contact with both surfaces of the polymer electrolyte membrane.

The second aspect of the present invention is:
2. The membrane electrode assembly according to claim 1, wherein the height of the periodically arranged fine irregularities is 1 μm or more and 50 μm or less.

The third aspect of the present invention is:
3. The membrane electrode assembly according to claim 1, wherein the periodically arranged cross-sections of fine irregularities have a two-fold rotation axis.

The fourth aspect of the present invention is:
The membrane electrode assembly according to any one of claims 1 to 3, wherein the periodically arranged cross-sections of fine irregular shapes include any one of an equilateral triangle, an isosceles triangle, and an unequal triangle. It is.

The fifth aspect of the present invention is:
The membrane electrode assembly according to any one of claims 1 to 3, wherein the periodically arranged cross-sections of the fine concavo-convex shape include any one of a semicircular shape, a semielliptical shape, and a saddle shape. is there.

The sixth aspect of the present invention is:
The membrane electrode assembly according to any one of claims 1 to 3, wherein the periodically arranged cross-sections of fine irregular shapes include an isosceles trapezoid or an unequal leg trapezoid.

The seventh aspect of the present invention is:
The membrane electrode assembly according to any one of claims 1 to 3, wherein the periodically arranged cross-sections of fine irregularities include any one of a sine waveform, a triangular waveform, and a trapezoidal waveform. .

The eighth aspect of the present invention is:
The membrane electrode assembly according to any one of claims 1 to 7, wherein the periodically arranged cross-sections of fine irregularities include a shape in which the curvature continuously changes.

The ninth aspect of the present invention is:
The membrane electrode junction according to any one of claims 1 to 8, wherein the fine irregularities arranged periodically are formed of a plurality of line-like structures extending in one direction and arranged in parallel. Is the body.

The tenth aspect of the present invention is:
A solid polymer fuel cell comprising the membrane electrode assembly according to any one of claims 1 to 9.

The eleventh aspect of the present invention is:
A method for producing a membrane electrode assembly comprising an anode electrode, a cathode electrode, and a polymer electrolyte membrane,
Laminating an anode electrode on one surface of the polymer electrolyte membrane and laminating a cathode electrode on the other surface so as to face the anode electrode;
A gasket having a fine concavo-convex shape which is a frame shape having a size along the outer periphery of the anode electrode and the cathode electrode and periodically arranged on at least a part of one surface thereof includes the fine concavo-convex shape. A step of laminating facing the both sides of the polymer electrolyte membrane so that the surface is in contact with the polymer electrolyte membrane;
And at least a step of aligning and positioning the lamination position of the anode electrode and the gasket on the anode electrode side, and the lamination position of the cathode electrode and the cathode electrode side gasket,
In the method of manufacturing a membrane electrode assembly, the length of the orthogonal projection in the shortest line segment of the slope in the cross-section of the fine uneven shape of the gasket is larger than the alignment accuracy by the alignment control.

The twelfth aspect of the present invention is
A method for producing a membrane electrode assembly comprising an anode electrode, a cathode electrode, and a polymer electrolyte membrane,
Prepare a gasket having a fine concavo-convex shape in a frame shape having a size along the outer periphery of the anode electrode and the cathode electrode and periodically arranged on at least a part of one surface thereof,
Laminating the anode electrode on the support, laminating the gasket so that the surface with the fine irregularities of the gasket faces the opposite side of the support, and is adjacent to the outer periphery of the anode electrode;
Laminating a cathode electrode on another support, laminating the gasket so as to be adjacent to the outer periphery of the cathode electrode, with the finely uneven surface of the gasket facing the opposite side of the support;
Laminating on one surface of the polymer electrolyte membrane so that the anode electrode and the gasket are in contact with the polymer electrolyte membrane;
Laminating the other surface of the polymer electrolyte membrane so that the cathode electrode and the gasket are in contact with the polymer electrolyte membrane;
And at least a step of aligning and controlling the lamination position of the anode electrode and the cathode electrode facing each other across the polymer electrolyte membrane,
In the method of manufacturing a membrane electrode assembly, the length of the orthogonal projection in the shortest line segment of the slope in the cross-section of the fine uneven shape of the gasket is larger than the alignment accuracy by the alignment control.

  According to the method for manufacturing a membrane electrode assembly according to the present invention, it is possible to improve the alignment accuracy when stacking the anode electrode and the cathode electrode as compared with the conventional transfer method, and to improve the quality of the membrane electrode assembly. Thus, sufficient power generation and durability can be exhibited in MEAs, unit cells, cell stacks, and fuel cells using this manufacturing method.

It is sectional drawing which shows the manufacturing method of the membrane electrode assembly which concerns on embodiment of this invention. It is a perspective view which shows the manufacturing method of the membrane electrode assembly which concerns on embodiment of this invention. It is sectional drawing which shows the manufacturing method of the membrane electrode assembly which concerns on other embodiment of this invention. It is a perspective view which shows the manufacturing method of the membrane electrode assembly which concerns on other embodiment of this invention. It is the perspective view and sectional drawing which show the example of a shape of the gasket which concerns on embodiment of this invention. It is the perspective view and sectional drawing which show the example of a shape of the gasket which concerns on embodiment of this invention. It is the perspective view and sectional drawing which show the example of a shape of the gasket which concerns on embodiment of this invention. It is the perspective view and sectional drawing which show the example of a shape of the gasket which concerns on embodiment of this invention. It is the perspective view and sectional drawing which show the example of a shape of the gasket which concerns on embodiment of this invention. It is the perspective view and sectional drawing which show the example of a shape of the gasket which concerns on embodiment of this invention. It is the perspective view and sectional drawing which show the example of a shape of the gasket which concerns on embodiment of this invention. It is the perspective view and sectional drawing which show the example of a shape of the gasket which concerns on embodiment of this invention. It is the schematic which shows the structural example of the polymer electrolyte fuel cell which concerns on embodiment of this invention. It is sectional drawing for demonstrating the effect of embodiment of this invention.

  Embodiments of the present invention will be described below with reference to the drawings. Each figure is a schematic diagram, and the size, shape, and the like of each part are appropriately exaggerated for easy understanding. For the sake of simplicity, the same reference numerals are given to corresponding parts in the drawings. The present invention is not limited to the embodiments described below, and modifications such as design changes can be added based on the knowledge of those skilled in the art. Embodiments to which such modifications are added Are also included in the scope of the embodiments of the present invention.

(overall structure)
First, a polymer electrolyte fuel cell using a membrane electrode assembly to which an embodiment of the present invention can be applied will be described with reference to FIG.

  FIG. 13 is a schematic view showing a configuration example of the polymer electrolyte fuel cell 11 according to one embodiment of the present invention. As shown in FIG. 13, the polymer electrolyte fuel cell 11 according to this embodiment includes a membrane electrode assembly 12 having an anode electrode 2 and a cathode electrode 3 on both surfaces of a polymer electrolyte membrane 1, and the anode electrode 2. The gas diffusion layer 5 is disposed opposite to the cathode electrode 3, and the frame-like gasket 4 is provided on the outer periphery of the anode electrode 2, the cathode electrode 3, and the gas diffusion layer 5. Consists of.

The separator 10 is made of a material that is conductive and impermeable. The separator 10 includes a gas flow path 8 for gas flow and a cooling water flow path 9 for cooling water flow formed on a main surface opposite to the surface on which the gas flow path 8 is formed. The separator 10 is disposed so as to sandwich the gasket 4 and the gas diffusion layer 5.
Fuel gas is supplied from the gas flow path 8 of the separator 10 on the anode 6 side. An example of the fuel gas is hydrogen gas. An oxidant gas is supplied from the gas flow path 8 of the separator 10 on the cathode 7 side. As the oxidant gas, for example, a gas containing oxygen such as air is supplied.
Hereinafter, when there is no need to distinguish between the anode electrode 2 and the cathode electrode 3, the electrode 2 (3) may be expressed. Or it may be an electrode layer. Further, the anode electrode and the cathode electrode may be called catalyst layers because they are layers that fulfill the function of a catalyst in the membrane electrode assembly.

As shown in FIG. 13, the polymer electrolyte fuel cell 11 according to this embodiment includes a set of separators 10, a polymer electrolyte membrane 1, an anode electrode 2, a cathode electrode 3, a gasket 4, and a gas. This is a solid polymer fuel cell having a so-called single cell structure in which a diffusion layer 5 is sandwiched.
However, in the present embodiment, a stack structure in which a plurality of cells are stacked in series via the separator 10 may be employed.

(Membrane electrode assembly)
Next, a configuration of the membrane electrode assembly 12 using the gasket 4 according to the present embodiment will be described with reference to FIGS. 1 to 4. The details of the contents will be described in the description of the bonding step described later.

In the embodiment shown in FIGS. 1 and 2, the support 2 is provided on the surface opposite to the surface facing the polymer electrolyte membrane 1 of the electrode 2 (3) and the gasket 4.
The membrane electrode assembly 12 has an anode electrode 2 and a cathode electrode 3 on both surfaces of the polymer electrolyte membrane 1, and has a gasket 4 on the outer periphery of the electrode 2 (3). Further, in at least a partial region of the gasket 4, the surface having contact with the polymer electrolyte membrane 1 has a periodicity as shown in FIGS. 1 (a) and 1 (b) and FIGS. 3 (a) and 3 (b). The uneven shape is formed.

  Since the electrode 2 (3) has a fine irregular shape in this way, the alignment accuracy in the y-axis direction of the anode electrode 2 and the cathode electrode 3 is improved, and performance degradation due to gas leakage, deterioration promotion of the electrolyte membrane, etc. are improved. It can suppress and can maintain the power generation efficiency of a fuel cell.

(gasket)
Details of the fine uneven shape provided on the surface of the gasket 4 according to the present embodiment will be described with reference to FIGS.

The gasket 4 has a fine concavo-convex shape that extends substantially parallel to the longitudinal direction (x-axis direction in the drawing) of the catalyst layer on the xy plane and has periodicity. It is possible to mesh the concavo-convex shape by inverting so as to face each other.

Immediately before the gasket 4 is bonded to both sides of the polymer electrolyte membrane 1, there is a deviation amount C ′ (not shown) due to alignment accuracy caused by an alignment method or an apparatus / jig as described later. Conventionally, since it is fixed by performing pressure bonding or the like in this state, the shift amount C ′ becomes the alignment accuracy of the gasket as it is.
On the other hand, when the gasket 4 having a fine uneven shape is engaged with the polymer electrolyte membrane 1 and crimped as in the present invention, the concave and convex portions of the uneven shape of the gasket are formed into the polymer electrolyte membrane 1. The force that shifts the position of the gasket 4 in the y direction in the figure acts in a self-aligning manner so that the meshes are meshed well, and as a result, the amount is smaller than the shift amount C ′. Thereby, the alignment precision of the gasket 4 and the anode electrode 2 and the cathode electrode 3 which oppose improves compared with the conventional bonding method.

  As long as the outer shape of the fine concavo-convex shape is a shape that can be easily produced and maintained, and can efficiently improve the alignment position accuracy of the anode electrode 2 and the cathode electrode 3, only the shape described in the present invention. It is not limited to.

In the figure, the height on the yz plane, the pitch, the length of the flat surface, and the maximum inclination are described as H, P, L, and θ, respectively.
Further, when the catalyst layer is square, any side may be regarded as the longitudinal direction.

When the height H of the fine uneven shape is extremely small, specifically less than 1 μm, there is almost no difference from the case where the gasket surface is flat, so that it shows superiority in alignment accuracy. Hateful. Further, when the height H of the fine uneven shape is extremely large, specifically, when it exceeds 50 μm, the height (thickness) of the entire membrane electrode assembly 12 including the gasket 4 increases, and the stack increases. This is not preferable because the fuel cell becomes large.
Accordingly, the height H of the fine uneven shape is preferably 1 μm or more and 50 μm or less. In other words, it is preferable that the ten-point average roughness Rz of the fine uneven shape is 1 μm or more and 50 μm or less.

  When the gasket on the anode electrode layer 2 side and the gasket on the cathode electrode layer 3 side are laminated, bonded, or crimped, alignment (positioning) is performed manually or by mechanical control. It is necessary to optimize the shape.

According to the inventor's investigation, the length S of the orthogonal projection in the shortest line segment of the slope in the fine uneven shape provided on the surface of the gasket 4 is larger than the alignment accuracy caused by the bonding jig or apparatus. In this case, it has been found that the alignment accuracy is improved as compared with the prior art. Here, the length S of the orthogonal projection in the shortest line segment of the slope refers to S shown in FIGS.
This is the force that shifts the position so that the concave and convex portions of the concave and convex shape are well meshed with each other as described above when the length S is smaller than the alignment accuracy caused by the alignment method described later at the time of bonding and crimping. This is thought to be because it does not work in a self-aligning manner and is kept as is.

Even if the gasket 4 has a concavo-convex shape extending substantially parallel to the short side direction (y-axis direction in the drawing) of the catalyst layer on the xy plane, a certain effect can be obtained, but the longitudinal direction ( An uneven shape extending substantially parallel to the (x-axis direction) is preferable because it is possible to further reduce the positional deviation between the anode electrode layer 2 and the cathode electrode layer 3 or the gap between the electrode layer and the gasket.
The misregistration and gap here refer to C and G shown in FIGS. 14 (a) and 14 (b).

Examples of the surface shape of the gasket 4 include sinusoidal, triangular, and trapezoidal wave shapes. The perspective view and sectional view are shown in FIGS.
Note that the sinusoidal waveform, triangular wave, and trapezoidal wave here do not have to be geometrically accurate sinusoidal waveforms, triangular waves, or trapezoidal waves, and are used for convenience to classify the shapes typi- cally. The waveform shape has a certain property, and a part thereof may include a straight line, a curve, and a distortion.

  Furthermore, another example of the surface shape of the gasket 4 is a shape having a flat surface between fine irregularities. The perspective view and sectional view are shown in FIGS. The shape as shown in FIGS. 8 to 10 is called a shape having rotational symmetry and a two-fold rotation axis. The two-fold rotation axis is a figure that coincides with the original figure when rotated by a half rotation, that is, 180 degrees. Means.

  Another example of the surface shape of the gasket 4 includes a triangular wave and a trapezoidal wave chamfered by a flat surface or a curved surface. The perspective view and sectional view are shown in FIGS.

  The fine concavo-convex shape as shown in FIGS. 5 to 12 does not have to be exactly parallel to the x-axis in the drawings.

  FIGS. 5 to 12 show an example in which minute uneven shapes having exactly the same shape are arranged in parallel, but the present invention is not limited to this, and it may be configured by appropriately combining FIGS. 4 to 12 and other shapes on the gasket surface. Good.

  The membrane electrode assembly 12 according to the present embodiment has a fine uneven shape on the surface of the gasket 4, but the gasket on the anode electrode 2 side and the gasket on the cathode electrode 3 side may have the same shape, It may have a different shape.

  The fine uneven shape of the gasket 4 may be provided only on one side or on both sides.

  The gasket 4 may have a single layer structure or a multilayer structure. Furthermore, the gasket 4 may be composed of only the main material, or a plurality of materials may be combined.

Examples of main materials for forming the gasket 4 include, for example, polycarbonate resin, polystyrene resin, fluorine-based acrylic resin, epoxy acrylate resin, methylstyrene resin, fluorene resin, polyethylene resin, polypropylene resin, polyurethane resin, polymethylpentene resin, polybutene resin. , Polyvinyl alcohol, polyvinyl chloride, polyvinylidene fluoride, polyamide, polyimide, polymethyl methacrylate, cycloolefin polymer, polyethylene terephthalate, polyethylene naphthalate, polyether ether ketone, polyether sulfone, polyether ether imide, polyphenylene sulfide, Ethylene-vinyl acetate copolymer, acrylic-styrene copolymer, styrene-butadiene-acrylonitrile Various commonly used acrylic resins such as polymers, silicone resins, polylactic acid, and cellulose, polyester resins, polyolefin resins, general-purpose plastics, engineering plastics, super engineering plastics, synthetic polymer resins, natural resins, UV Examples thereof include curable resins, thermosetting resins, and thermoplastic resins.
Of these, two or more kinds of mixed materials may be used.

The gasket 4 may have an adhesive layer or an adhesive layer on part or all of the surface, and the surface of the gasket 4 may have tackiness (adhesiveness).
Further, when the polymer electrolyte membrane 1 and the gasket 4 are laminated or bonded, the polymer electrolyte membrane 1 and the gasket 4 are bonded, bonded, bonded, and integrated by the above-mentioned adhesive layer, adhesive layer, or tack layer. Also good.

Examples of the manufacturing method of the surface shape of the gasket 4 include etching, electron beam drawing, laser drawing, laser interference, cutting, and self-organization. In addition, using the mold and plate shaped by the above method, pouring various materials melted into the mold and plate, curing, and then peeling off the mold and plate to form the desired shape. The gasket 4 which has can be obtained.
In addition, if the gasket 4 which finally has the same surface shape can be produced, there will be no restriction | limiting in particular about the production means.

  The fine concavo-convex shape of the gasket 4 can improve the adhesive force by increasing the contact area between the gasket 4 and the polymer electrolyte membrane 1, and can also suppress defects such as floating and peeling of the gasket 4.

  The fine uneven shape of the gasket 4 is due to the shear stress caused by the expansion or contraction of the membrane electrode assembly 12 due to the influence of temperature and humidity, etc., when the gaskets 4 are fitted to each other via the polymer electrolyte membrane 1. In addition, defects such as interlayer displacement, twisting, and wrinkles can be suppressed.

(Type / version)
Examples of main materials for forming the above-mentioned fine concavo-convex mold / plate include polycarbonate resin, polystyrene resin, fluorine-based acrylic resin, epoxy acrylate resin, methylstyrene resin, fluorene resin, polyethylene resin, polypropylene resin, polyurethane resin, Polymethylpentene resin, polybutene resin, polyvinyl alcohol, polyvinyl chloride, polyvinylidene fluoride, polyamide, polyimide, polymethyl methacrylate, cycloolefin polymer, polyethylene terephthalate, polyethylene naphthalate, polyether ether ketone, polyether sulfone, polyether Ether imide, polyphenylene sulfide, ethylene-vinyl acetate copolymer, acrylic-styrene copolymer, styrene-butadiene-acrylic Various commonly used acrylic resins such as nitrile copolymers, silicone resins, polylactic acid, and cellulose, polyester resins, polyolefin resins, general-purpose plastics, engineering plastics, super engineering plastics, synthetic polymer resins, natural resins UV curable resin, thermosetting resin, thermoplastic resin and the like.
Of these, two or more kinds of mixed materials may be used.

  Examples of main materials for forming molds and plates include gold, platinum, silver, copper, iron, lead, zinc, tin, titanium, vanadium, chromium, nickel, tungsten, aluminum, magnesium, solder, steel, brass, stainless steel, A metal or alloy such as duralumin, glass, ceramics, wood, paper, brick, concrete, rubber, or the like may be used.

Examples of mold / plate manufacturing methods include etching, electron beam drawing, laser drawing, laser interference, cutting, and self-organization. The desired shape can also be obtained by using the one shaped by the above method as a mold / plate, pouring various materials melted into the mold / plate, and curing and then peeling off the mold / plate recesses. A mold / plate with can be obtained as a duplicate.
If a mold / plate having the same surface shape can be finally produced, the production means is not particularly limited.

(Transcription)
Next, the bonding process of the electrode 2 (3) and the polymer electrolyte membrane 1 will be described with reference to FIGS.
First, as shown in FIGS. 1A and 2, the electrode 2 (3) and the gasket 4 held on the support 21 are arranged such that the surface having a fine uneven shape on the surface of the gasket 4 and the polymer electrolyte membrane 1. After facing each other, the electrode 2 (3) and the gasket 4 are laminated so as to be in contact with the polymer electrolyte membrane 1.

And these are integrated as shown in FIG.1 (b) using methods, such as thermocompression bonding. Finally, the support 21 is peeled from the electrode 2 (3) and the gasket 4 so that the electrode 2 (3) is transferred to the polymer electrolyte membrane 1 and at the same time the gasket 4 is bonded to the polymer electrolyte membrane 1. I can do it.
Thus, the membrane electrode assembly 12 can be produced by transferring the anode electrode 2 and the cathode electrode 3 to both surfaces of the polymer electrolyte membrane 1, respectively.

  In addition, although the optimum conditions for the above-described transfer process vary depending on the material, thickness, shape, and the like of the polymer electrolyte membrane 1, the electrode 2 (3), the gasket 4, and the support 21, the transfer temperature is higher than the glass transition point of the polymer electrolyte membrane 1. It is preferable to perform pressure bonding at a temperature lower than the melting point because chemical bonding between the polymer electrolyte membrane 1 and the electrode 2 (3) can be promoted and adhesion can be improved.

  As another method, as shown in FIGS. 3 and 4, after transferring the electrode 2 (3) to the polymer electrolyte membrane 1, a gasket 4 can be bonded separately.

  First, the electrode 2 (3) and the polymer electrolyte membrane 1 held on the support 21 are opposed to each other, and then laminated so that the electrode 2 (3) and the polymer electrolyte membrane 1 are in contact with each other. And these are integrated using methods, such as thermocompression bonding. Subsequently, by peeling the support 21 from the electrode 2 (3), the electrode 2 (3) can be transferred to the polymer electrolyte membrane 1 as shown in FIG. A membrane-catalyst layer assembly (CCM) can be produced by transferring the anode electrode 2 and the cathode electrode 3 to both surfaces of the polymer electrolyte membrane 1 by the same process.

  Thereafter, a gasket 4 having an opening part removed by means of cutting or punching is laminated and bonded to the polymer electrolyte membrane 1 so as to cover the periphery of the electrode 2 (3), and FIG. The membrane electrode assembly 12 as shown in FIG.

  In the above transfer step, the cathode electrode 3 may be transferred after the anode electrode 2 is transferred, or the anode electrode 2 may be transferred after the cathode electrode 3 is transferred. Further, in the case where a fine uneven shape is provided only on one surface of the gasket 4 as shown in FIG. 1 or FIG. 3, the side where the fine uneven shape is not formed may be formed by a known technique.

(Alignment method)
When the gasket on the anode electrode 2 side and the gasket on the cathode electrode 3 side are laminated, bonded, or pressure-bonded, it is preferable to align both electrodes manually or by machine control.

  As a specific example of the alignment method, the sample setting position or the mark (alignment mark) provided on the end of the catalyst layer or gasket or on a part of the gasket or support is accurately superimposed on the xy plane. Alignment can be performed by translating a table such as a suction disk holding the sample in the x and y directions, or changing the angle of the sample in the xy plane.

In order to perform alignment, visual means or an optical method using a camera can be used as means for recognizing a mark (alignment mark) provided at the end of the catalyst layer or the gasket or a part of the gasket or the support.
In the case of recognition by a camera, infrared light or ultraviolet light can be used in addition to visible light.

  The relationship between the camera and the light source may be dark field illumination, bright field illumination or coaxial epi-illumination. Moreover, reflected light may be used and transmitted light may be used.

(electrode)
The average thickness of the electrode 2 (3) obtained by applying and drying the catalyst ink may be, for example, from 0.1 μm to 100 μm, preferably from 0.5 μm to 50 μm, and more preferably from 1 μm to 20 μm.

  When the electrode 2 (3) is manufactured, it is preferable that the average thickness in the z-axis direction is uniform. However, the electrode 2 (3) is preferably used even if the average thickness in the z-axis direction is not exactly uniform. I can do it.

  Since the polymer electrolyte fuel cell 11 is manufactured by stacking a plurality of MEAs, the average thickness of the electrode 2 (3) in the z-axis direction is avoided in order to avoid performance degradation due to the crushing of the electrode 2 (3). Is preferably smaller than the maximum thickness of the gasket 4.

As a method for applying the catalyst ink, a conventional coating method can be used. Specific coating methods include, for example, roll coaters, air knife coaters, blade coaters, rod coaters, reverse coaters, bar coaters, comma coaters, die coaters, gravure coaters, screen coaters, sprayers, spinners and the like.
If the same catalyst ink can be finally applied, the application means is not particularly limited.

The above application means can be applied to the production of either the anode electrode 2 or the cathode electrode 3, but is not limited to the same application conditions in both productions. In the manufacturing process of the cathode electrode 3, different coating conditions can be used.
The application conditions referred to here comprehensively refer to the method of the coating device, the number, the discharge pressure of the catalyst ink, the discharge time, the sweep speed, the coating width, the coating length, the distance between the coater and the mold, and the like.

  Examples of the drying means for the catalyst ink include a heatable adsorbing plate, a hot plate, an oven, an IR dryer, blowing hot air, natural drying over time, etc., but finally a similar electrode or catalyst layer can be obtained. There is no particular limitation. Furthermore, in the drying process of the catalyst ink, a plurality of drying methods may be used in combination, and temperature conditions may be different for each drying method.

The drying means described above can be applied to the production of both the anode electrode 2 and the cathode electrode 3, but is not limited to the same drying conditions in both productions. In the manufacturing process of the cathode electrode 3, different drying conditions can be used.
The drying conditions here comprehensively refer to the method and number of dryers when drying the catalyst ink, temperature, humidity, drying time, and the like.

(Catalyst ink)
The catalyst ink is obtained by dissolving or dispersing a polymer electrolyte, a catalyst, and conductive particles in a solvent. Here, the anode catalyst ink and the cathode catalyst ink may have the same composition or different compositions.

The solvent used in the catalyst ink is not particularly limited as long as it can dissolve or disperse the polymer electrolyte and the catalyst.
For example, water, alcohols (methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 3-butanol, pentanol, ethylene glycol, diacetone alcohol, 1-methoxy-2-propanol, etc.) , Ketones (acetone, methyl ethyl ketone, pentanone, methyl isobutyl ketone, diisobutyl ketone, etc.), ethers (dioxane, tetrahydrofuran, etc.), sulfoxides (dimethyl sulfoxide, etc.), amides (dimethylformamide, dimethylacetamide, etc.), etc. These can be used singly or in combination.
The solvent used in the catalyst ink is preferably one that can be easily removed by heating, and one having a boiling point of 150 ° C. or less is particularly suitable.

The conductive particles used in the catalyst ink are not particularly limited as long as they are in the form of fine particles and have conductivity and are not attacked by the catalyst.
Examples thereof include carbon black (acetylene black, furnace black, ketjen black, etc.), graphite, graphite, activated carbon, carbon fiber, carbon nanotube, fullerene and the like.
Moreover, the particle size of the conductive particles is preferably about 10 nm to 100 nm.

The catalyst used in the catalyst ink is not particularly limited as long as it is a metal component having a catalytic action.
For example, in addition to platinum group elements such as platinum, palladium, ruthenium, iridium, rhodium, osmium, metals such as iron, lead, copper, chromium, cobalt, nickel, manganese, vanadium, molybdenum, gallium, aluminum, or the above metals Examples include alloys containing a plurality of types, oxides thereof, and double oxides. Of these, platinum and platinum alloys are particularly preferable.
In addition, a catalyst having a particle size of about 0.5 nm to 20 nm is preferably used from the viewpoint of activity and stability.

The polymer electrolyte used in the catalyst ink is not particularly limited as long as it is a resin component having proton conductivity, and among them, a fluorine-based polymer electrolyte or a hydrocarbon-based polymer electrolyte is preferably used.
Examples of the fluoropolymer electrolyte include Nafion (registered trademark) manufactured by DuPont, Flemion (registered trademark) manufactured by Asahi Glass Co., Ltd., Aciplex (registered trademark) manufactured by Asahi Kasei Co., Ltd., and Gore Select (registered trademark) manufactured by Gore. Etc. can be used.
As the hydrocarbon polymer electrolyte, for example, electrolytes such as sulfonated polyether ketone, sulfonated polyethersulfone, sulfonated polyetherethersulfone, sulfonated polysulfide, and sulfonated polyphenylene can be used.

  The concentration of the solute (conductive particles, catalyst particles, polymer electrolyte) in the catalyst ink is, for example, 1% by weight to 80% by weight, preferably 5% by weight to 60% by weight, and more preferably 10% by weight or more. Used at about 40% by weight or less.

  The catalyst ink can be prepared by mixing the above solvent, conductive particles, catalyst, and polymer electrolyte and applying a dispersion treatment. Examples of the dispersion method include ball mill, bead mill, roll mill, shear mill, wet mill, ultrasonic dispersion, and homogenizer.

  As the catalyst ink for forming the anode electrode 2 and the cathode electrode 3, the same catalyst ink may be used, or different catalyst inks may be used for the anode and the cathode.

(Polymer electrolyte membrane)
The polymer electrolyte used for the polymer electrolyte membrane 1 is not particularly limited as long as it is a resin component having proton conductivity, and among them, a fluorine-based polymer electrolyte or a hydrocarbon-based polymer electrolyte is preferably used.
Examples of the fluoropolymer electrolyte include Nafion (registered trademark) manufactured by DuPont, Flemion (registered trademark) manufactured by Asahi Glass Co., Ltd., Aciplex (registered trademark) manufactured by Asahi Kasei Co., Ltd., and Gore Select (registered trademark) manufactured by Gore. Etc. can be used.
As the hydrocarbon polymer electrolyte, for example, electrolytes such as sulfonated polyether ketone, sulfonated polyethersulfone, sulfonated polyetherethersulfone, sulfonated polysulfide, and sulfonated polyphenylene can be used.

  The average thickness of the polymer electrolyte membrane 1 is, for example, about 1 μm to 500 μm, preferably about 3 μm to 200 μm, and more preferably about 5 μm to 100 μm.

(Support)
The support 21 may have a single layer structure or a multilayer structure. Furthermore, the support 21 may be composed of only the main material, or a plurality of materials may be combined.

  As a film used for the support 21, a catalyst ink can be applied to at least one side of the support 21 and an electrode 2 (3) can be formed by heating, or an adhesive layer bonded on the support 21 is used. The gasket 4 is not particularly limited as long as it can hold the gasket 4 and can intentionally peel off the support 21 and the gasket 4.

  For example, polyethylene terephthalate, polyamide, polyimide, polystyrene, polysulfone, polyethersulfone, polyphenylene sulfide, polyetheretherketone, polyetherimide, polybenzimidazole, polyamideimide, polyacrylate, polyethylene naphthalate, polypalvanic acid aramid, etc. Heat resistance of molecular film or polytetrafluoroethylene, polychlorotrifluoroethylene, polyvinylidene fluoride, ethylene tetrafluoroethylene copolymer, tetrafluoroethylene-hexafluoropropylene copolymer, tetrafluoroperfluoroalkyl vinyl ether copolymer, etc. Fluorine resin film can be used.

  The membrane electrode assembly 12 according to the present invention manufactured as described above has high positional accuracy of the gasket 4 and can exhibit high deterioration resistance alone.

A membrane / electrode assembly according to the present invention was prepared by the method described below, and the positional accuracy by alignment was evaluated.
(Method for preparing catalyst ink)
As a catalytic substance-supporting carbon body, platinum-supporting carbon (trade name: manufactured by Tanaka Kikinzoku Co., Ltd.) and a solvent were kneaded using a 0.2φ bead mill (trade name: YTZ ball, manufactured by Nikkato Co., Ltd.) made of zirconia. Next, an ionomer solution (trade name: SS-700C / 20, manufactured by Asahi Kasei E-Materials Co., Ltd.), which is a 20% by mass polymer electrolyte solution, was added as a polymer electrolyte, and kneaded again to prepare a catalyst ink.
In the configuration of the membrane electrode assembly 12 to be described later, different catalyst types are used for the anode electrode 2 and the cathode electrode 3, TEC10F30E-HT is used for the anode electrode 2, and TEC10F50E-HT is used for the cathode electrode 3.

(Production of membrane electrode assembly 1)
A method for preparing a sample of the membrane electrode assembly 12 according to the present invention will be described.
First, the substrate was fixed to the adsorption table by sucking air so as not to cause wrinkles or floats, and the catalyst ink was discharged from the coating die. Here, the catalyst ink was uniformly coated on the substrate and dried by moving the stage in parallel with the substrate fixed.

  Next, the gasket 4 and the substrate with the electrode layer are bonded to one side of the support 21, and the substrate with the electrode layer and the gasket are formed by half-cutting from the electrode side using a rectangular blade shape of 50 mm × 150 mm. Punching was performed. After punching, the frame-shaped gasket could be exposed on the outer periphery of the electrode layer by peeling the substrate with the electrode layer only outside the opening. A schematic diagram at this time is shown in FIG.

Subsequently, the bonded product of the support 21, the gasket 4, and the substrate with the electrode layer is disposed so as to face both surfaces of the polymer electrolyte membrane 1, and the anode electrode is used with a bonding machine having an automatic alignment function. Lamination and bonding were performed while aligning the ends of 2 and the cathode electrode 3 so as to overlap each other. A schematic diagram at this time is shown in FIG.
Then, pressurizing for 5 minutes while applying a temperature of 100 to 150 ° C. using a hydraulic hot press machine, and peeling off the support 21 and the base material of the opening, whereby the electrode 2 (3) is attached to the polymer electrolyte membrane 1. At the same time, the gasket 4 was bonded to prepare a membrane electrode assembly 12.
In each of the samples, the values of the above-mentioned gasket shape type, uneven height H, projection S, pitch P, flat surface length L, and base angle θ were the values shown in Tables 1 and 2. . Here, the sample of Comparative Example 1 is a sample in which a fine uneven shape is not provided on the gasket surface, that is, the gasket surface is smooth.

(Position accuracy evaluation 1)
With reference to data from a membrane / electrode assembly (Comparative Example 1) produced without providing fine irregularities on the gasket surface, the positional displacement of the end portions of the anode electrode 2 and the cathode electrode 3 in the y-axis direction, in other words, FIG. When the value of C shown in (a) is smaller than the reference, the mark is ◯, and when the value is larger than the reference, the mark is ×.

  Tables 1 and 2 below list the comparison results when measuring the cross section of the sample using the SEM. In addition, with respect to the value 9.8 μm of the positional deviation amount C of Comparative Example 1, samples having an orthographic projection S larger than this were designated Examples 1 to 12, and samples smaller than this were designated Comparative Examples 2 to 10.

(Production of membrane electrode assembly 2)
First, the mask and the base material are bonded together, and the mask is punched by half-cutting from the mask side using a rectangular blade shape of 50 mm × 150 mm. After the punching process, the mask was peeled only inside the opening, and the mask side was fixed to the suction table by suction of air so that wrinkles and floats did not occur, and the catalyst ink was discharged from the coating die. Here, the catalyst ink was uniformly applied onto the substrate with the mask by moving the stage in parallel while fixing the substrate with the mask. After drying the catalyst ink, the mask was peeled off to form an electrode layer having a desired shape on the substrate.

Next, the base material with the electrode layer is disposed so as to face both surfaces of the polymer electrolyte membrane 1, and the ends of the anode electrode 2 and the cathode electrode 3 are overlapped by a bonding machine having an automatic alignment function. Laminating and pasting were performed while aligning with each other.
Subsequently, pressurizing for 5 minutes while applying a temperature of 100 to 150 ° C. using a hydraulic hot press machine to peel off the base material, thereby producing a CCM in which the electrode 2 (3) is transferred to the polymer electrolyte membrane 1. did. A schematic view at this time is shown in FIG.
Then, the membrane electrode assembly 12 was produced by sticking the frame-shaped gasket 4 which has an opening part of 50 mm x 150 mm to the outer periphery of an electrode layer. A schematic diagram at this time is shown in FIG.

(Position accuracy evaluation 2)
Based on data from a membrane / electrode assembly (Comparative Example 11) produced without forming fine irregularities on the gasket surface, the gaps between the end portions of the anode electrode 2 and the cathode electrode 3 in the y-axis direction and the gasket, in other words, The value of G shown in FIG. 14B is smaller than the reference, and the larger value than the reference is ×.

  Table 3 below shows a list of comparison results when the sample cross section was measured using SEM. In Table 3, with respect to the positional deviation (gap) G value of 13.2 μm in Comparative Example 11, samples having an orthographic projection S value larger than this are designated as Examples 13 to 17, and samples smaller than this are designated as Comparative Example 12. It was set to ~ 18.

From the evaluation results of Tables 1 to 3, when the membrane electrode assembly according to the present invention is used, the length S of the orthogonal projection of the shortest line segment of the slope in the y-axis direction of the fine unevenness provided on the gasket surface is As for the larger displacement than that caused by the conventional alignment, a significant difference can be confirmed that the displacement is smaller than the reference value (Comparative Example 1 or Comparative Example 11) in all shapes and vice versa. It was.
From the above results, according to the present invention, in the production of a membrane electrode assembly for a fuel cell, it was possible to improve alignment accuracy during lamination and bonding.

  The production method according to the present invention can be suitably used in various applications as well as the membrane electrode assembly for fuel cells.

1 ... Polymer electrolyte membrane 2 ... Anode electrode (oxidation electrode or fuel electrode)
3 ... Cathode electrode (reduction electrode or air electrode)
DESCRIPTION OF SYMBOLS 4 ... Gasket 5 ... Gas diffusion layer 6 ... Anode 7 ... Cathode 8 ... Gas flow path 9 ... Cooling water flow path 10 ... Separator 11 ... Solid polymer fuel Battery 12 ... Membrane electrode assembly 13 ... Electrolyte membrane with catalyst layer 21 ... Support

Claims (12)

A membrane electrode assembly comprising an anode electrode on one surface of a polymer electrolyte membrane and a cathode electrode on the other surface, and gaskets adjacent to each other along the outer periphery of the anode electrode and the cathode electrode,
At least a part of the surface of the gasket has fine irregularities arranged periodically,
The fine concavo-convex shape is in contact with both surfaces of the polymer electrolyte membrane so as to face each other.   2. The membrane electrode assembly according to claim 1, wherein the height of the periodically arranged fine irregularities is 1 μm or more and 50 μm or less.   The membrane electrode assembly according to claim 1 or 2, wherein the periodically arranged cross-sections of fine irregularities have a two-fold rotation axis.   The membrane electrode assembly according to any one of claims 1 to 3, wherein the periodically arranged cross-sections of fine irregular shapes include any one of an equilateral triangle, an isosceles triangle, and an unequal triangle. .   The membrane electrode assembly according to any one of claims 1 to 3, wherein the cross-sections of the fine irregularities arranged periodically include any of a semicircular shape, a semielliptical shape, and a saddle shape.   The membrane electrode assembly according to any one of claims 1 to 3, wherein the periodically arranged cross-sections of fine irregularities include an isosceles trapezoid or an unequal leg trapezoid.   The membrane electrode assembly according to any one of claims 1 to 3, wherein the periodically arranged cross-sections of fine unevenness include any one of a sine waveform, a triangular waveform, and a trapezoidal waveform.   The membrane electrode assembly according to any one of claims 1 to 7, wherein the cross-sections of the fine concavo-convex shape arranged periodically include a shape whose curvature changes continuously.   The membrane electrode junction according to any one of claims 1 to 8, wherein the fine irregularities arranged periodically are formed of a plurality of line-like structures extending in one direction and arranged in parallel. body.   A solid polymer fuel cell comprising the membrane electrode assembly according to any one of claims 1 to 9. A method for producing a membrane electrode assembly comprising an anode electrode, a cathode electrode, and a polymer electrolyte membrane,
Laminating an anode electrode on one surface of the polymer electrolyte membrane and laminating a cathode electrode on the other surface so as to face the anode electrode;
A gasket having a fine concavo-convex shape which is a frame shape having a size along the outer periphery of the anode electrode and the cathode electrode and periodically arranged on at least a part of one surface thereof includes the fine concavo-convex shape. A step of laminating facing the both sides of the polymer electrolyte membrane so that the surface is in contact with the polymer electrolyte membrane;
And at least a step of aligning and positioning the lamination position of the anode electrode and the gasket on the anode electrode side, and the lamination position of the cathode electrode and the cathode electrode side gasket,
A method of manufacturing a membrane electrode assembly, wherein a length of an orthogonal projection in a shortest line segment of a slope in a cross-section of the fine uneven shape of the gasket is larger than an alignment accuracy by the alignment control. A method for producing a membrane electrode assembly comprising an anode electrode, a cathode electrode, and a polymer electrolyte membrane,
Prepare a gasket having a fine concavo-convex shape in a frame shape having a size along the outer periphery of the anode electrode and the cathode electrode and periodically arranged on at least a part of one surface thereof,
Laminating the anode electrode on the support, laminating the gasket so that the surface with the fine irregularities of the gasket faces the opposite side of the support, and is adjacent to the outer periphery of the anode electrode;
Laminating a cathode electrode on another support, laminating the gasket so as to be adjacent to the outer periphery of the cathode electrode, with the finely uneven surface of the gasket facing the opposite side of the support;
Laminating on one surface of the polymer electrolyte membrane so that the anode electrode and the gasket are in contact with the polymer electrolyte membrane;
Laminating the other surface of the polymer electrolyte membrane so that the cathode electrode and the gasket are in contact with the polymer electrolyte membrane;
And at least a step of aligning and controlling the lamination position of the anode electrode and the cathode electrode facing each other across the polymer electrolyte membrane,
A method of manufacturing a membrane electrode assembly, wherein a length of an orthogonal projection in a shortest line segment of a slope in a cross-section of the fine uneven shape of the gasket is larger than an alignment accuracy by the alignment control.