JP2021082597A - Manufacturing method of fuel battery, and fuel battery - Google Patents

Abstract

To manufacture a membrane/electrode assembly without deformation by applying electrode ink consisting of carbon and water or alcohol solvent, or water and alcohol solvent, or core-shell type electrode ink in which an electrolyte solution and catalyst are supported on a thin and delicate electrolyte membrane for a fuel battery.SOLUTION: A small-diameter roll is provided upstream of a heat-adsorption roll, electrode ink is applied by using a slot nozzle for electrode formation on at least one side of the small-diameter roll or the OFF roll, and a solvent is instantly evaporated by a heat-adsorption roll to form an electrode.SELECTED DRAWING: Figure 1

Description

The present invention mainly relates to a coating method using a head called a slot die, a slit die, a slot nozzle, or the like in the industry of applying a liquid film to a long object to be coated. For example, a method for forming an electrode of a fuel cell, particularly a PEFC (Polymer Electrolyte membrane Fuel Cell) type fuel cell, and an MEA (membrane electrode assembly) and a fuel cell manufactured by the method are included.
The material and shape of the object to be coated, the material to be coated, etc. are not particularly limited, but the electrode ink is directly slotted in the electrolyte membrane in order to be applied to the CCM (Catalyst coated membrane) type electrolyte membrane / electrode forming method of MEA. Applying with a nozzle to form an electrode is particularly effective in terms of productivity.

Conventionally, an electrolyte solution, which is a kind of ionomer, and fine powder consisting of carbon particles and platinum supported on carbon fibers are mixed with an electrolyte membrane, applied to GDL (Gas diffusion layer) as an electrode catalyst ink, and pressure-bonded to the electrolyte membrane. Or, it was applied to a release film such as PTFE and transferred to an electrolyte membrane. Since the crimping method and the transfer method do not involve liquid, resistance between the electrolyte membrane and the electrodes is generated, which deteriorates the performance of the fuel cell. In order to solve this problem, a method of directly applying the CCM type electrode catalyst ink to the electrolyte membrane has been proposed.

Patent Document 1 is a method invented by the present inventor, in which an electrode ink is sprayed in a state where an electrolyte film for roll to roll is unwound and adsorbed on a heated adsorption drum or adsorption belt. A method of laminating and coating and drying has been proposed. Since the electrolyte membrane is adsorbed and heated by heating of an adsorption drum or the like and laminated as a thin film by spraying or the like, the spray particles are instantly volatilized at the moment when they are applied to the electrolyte membrane and leveled. Therefore, since the electrolyte is not damaged and the adhesion is increased, the interfacial resistance between the electrode and the electrolyte membrane can be reduced to the utmost limit, so that an ideal CCM can be formed. In addition, since the electrolyte membrane is sucked by interposing a breathable paper wider than the electrolyte membrane between the adsorption drum and the electrolyte, the entire surface of the electrolyte membrane is made uniform without leaving adsorption marks of the porous body such as the adsorption drum. Proposals have also been made to suck.

Patent Document 2 is also a method invented by the present inventor, in which a film as an electrode-shaped mask is bonded to both sides of an electrolyte membrane for roll-to-roll to form an electrode-shaped recess. Then, a method has been proposed in which the electrode ink is laminated and applied while being unwound and adsorbed by a heated adsorption roll or adsorption belt and wound up. Also in this method, when applying the electrode ink, it is recommended to apply the electrode ink while sucking the electrolyte membrane with a heated adsorption drum or the like via a breathable base material.

The CCM method is ideal, but since the electrolyte membrane is sensitive to moisture and some Nafion membranes are instantly deformed when the electrode catalyst ink is applied, the electrolyte is used for the heat adsorption belt and heat adsorption roll as described above. Attempts have been made to apply the film with a spray nozzle, slot nozzle, or the like while adsorbing the film and moving it so as not to deform it. The spray required a mask to obtain the desired electrode pattern, and had a difficulty in increasing the production speed.
The slot nozzle is effective for increasing the production speed, but the "ON roll" placed on the heat adsorption roll has the following problems. Since the electrode ink is composed of platinum supported on carbon, ionomer, water, alcohol-based solvent, etc., when the heating roll is set to about 100 ° C or higher, the unheated slot nozzle is face-to-face with an electrolyte membrane. Condensation occurred at the tip due to water, solvent vapor, etc. of the electrode ink coated due to the temperature difference, which adversely affected the coated surface.
To prevent this, there is a method of heating the device including the nozzle, but if the temperature of the slot nozzle is high, the tip of the nozzle tends to dry, and the nozzle opening tends to become skinned and the electrode ink ejection tends to be unstable. there were.
Further, even if the adsorption roll is polished to a roundness of several microns or less at room temperature by a polishing device, the roll is greatly flexed and deformed due to its complicated structure when heated, and the roundness is extremely poor.
The amount of electrode catalyst required these days is extremely small, 0.15 mg or less per square centimeter at the anode electrode and 0.3 mg or less at the cathode electrode, and the specific gravity of the platinum catalyst is 20 or more, so that the film thickness is thin.
In addition, the ratio of platinum to carbon supporting platinum is 5: 5 and even 7: 3, so the dry film thickness including ionomer is extremely thin, which is 1 micrometer or less, and the solid content is 10%. In the case of, the wet film thickness is as thin as 10 micrometers or less.
When the heat adsorption roll is deformed, if it is performed by a method called a slit nozzle, a slot nozzle, or a slot die that contacts through a liquid film, the distance between the nozzle tip and the electrolyte membrane changes, and there is a problem that the distance becomes too far. It was. When such a phenomenon occurs, the amount of electrode ink applied is extremely small, and because the electrode ink is applied as a thin film, a scaly porous coating surface is formed at a location where the nozzle tip and the electrolyte film are far apart, and uniform coating is performed. It was extremely difficult to obtain.
In order to solve this problem, Japanese Patent Application Laid-Open No. 2010-149257 invented by the present inventors has proposed a method capable of polishing the surface of an adsorption roll while heated to an application temperature to reduce the roundness to 5 microns or less. However, in this method, polishing is required every time the roll temperature is changed, and the workability is extremely poor.
Further, in Japanese Patent Application Laid-Open No. 2015-15258, which is presumed to have polished the adsorption roll by cooling at room temperature, the roll that adsorbs the electrolyte film is cooled, electrode ink is applied to the electrolyte film with a slit nozzle, and the roll is rotated to move the cooling roll. A method of heating the electrode ink on the electrolyte membrane adsorbed on the surface with hot air or infrared rays in a subsequent process has been proposed.
However, in this method, it can be expected that the time from cooling to heating and drying after application, for example, the naphthion membrane, is damaged by the solvent shock solvent at the interface of the electrolyte membrane.

JP-A-2004-351413 JP-A-2005-63780

The present invention has been made to solve such a problem, and the heat adsorption roll does not pursue roundness, and is a means for rapidly drying the electrode ink applied to the electrolyte film without deformation. Therefore, since the emphasis is not placed on roundness, the manufacturing cost can be reduced to the utmost limit. On the other hand, it is common knowledge in the industry that the straightness of the tip of the slot nozzle should be 5 microns or less and even 2 microns or less at room temperature by polishing with a polishing device. It is important to reduce the influence of.
Further, the roundness of a small-diameter roll, for example, a diameter of 200 mm or less at room temperature can be suppressed to several microns or less by polishing with a polishing device. On the other hand, small-diameter rolls with a simple internal structure are used as crimping rolls for electrodes of secondary batteries because their roundness can be reduced to several microns or less even when heated.
Therefore, these small-diameter rolls are used in combination with a large-diameter heating adsorption roll with a diameter of 200 mm or more or a heating roll with a diameter of 250 mm or more, and a slot nozzle is installed on the ON roll or OFF roll to form an electrolyte membrane and the tip of the slot nozzle. Allows pattern coating of electrode ink while maintaining distance with high accuracy.
Since the electrolyte membrane is usually manufactured by the casting method and has a back sheet as a supporting base material, the coating for forming one of the electrodes can be applied by either a spray or a slot nozzle without deforming the electrolyte membrane. However, the electrolyte membrane is as thin as 25 microns or less and even 15 microns or less, and stretches when pulled, and as mentioned above, there are extremely delicate substrates that are easily deformed by the moisture in the air, so it is extremely difficult to form electrodes on the opposite surface. Further, it was extremely difficult to wind up the electrolyte membrane having electrodes formed on both sides of the electrolyte membrane.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to produce a high-quality and durable PEFC type fuel cell membrane / electrode manufacturing method and to produce CCM or MEA at high speed and provide them in large quantities. It is to be.
More specifically, the present invention is to directly apply electrode ink to a roll-to-roll electrolyte membrane to manufacture a high-performance film / electrode assembly, and eventually to manufacture a high-performance fuel cell.

The present invention is a method of continuously or intermittently moving a long electrolyte membrane for a fuel cell and applying electrode ink to at least one side of the electrolyte membrane with a slot nozzle to form an electrode, wherein the electrode ink is applied. A step of providing a heat-adsorption roll that heats and adsorbs the electrolyte membrane, and a step of providing at least one roll having a diameter smaller than that of the heat-adsorption roll in the vicinity of the heat-adsorption roll upstream of the heat-adsorption roll.
Provided is a method for manufacturing a fuel cell film / electrode assembly, which comprises a step of applying electrode ink with a slot nozzle between the small diameter roll and the contact of the electrolyte film with the heat adsorption roll.

The present invention provides a method for manufacturing a fuel cell membrane / electrode assembly, wherein the heating adsorption roll is a heating roll and moves while applying a tension of 20 to 80 Newton to the electrolyte membrane.

The present invention provides a method for manufacturing a membrane / electrode assembly of a fuel cell, wherein the heat adsorption roll is a heat adsorption belt.

The present invention manufactures a fuel cell membrane / electrode assembly, wherein 20 to 80 Newtons of tension is applied to the electrolyte membranes before and after the small diameter roll, and electrode ink is applied on the off-rolls before and after the small diameter roll. Provide a method.

The present invention provides a method for manufacturing a fuel cell membrane / electrode assembly, wherein the slot nozzle is an air assist slot nozzle or a mist ejection slit nozzle, and the distance between the electrolyte membrane and the nozzle head is set to 0 to 10 mm. provide.

In the present invention, the roundness of the heating adsorption roll or the heating roll is ± 50 micrometer or less, and the electrode ink is applied on the off-roll immediately before the electrolyte film comes into contact with the heating adsorption roll or the heating roll. Provided is a method for manufacturing a characteristic fuel cell membrane / electrode assembly.

In the present invention, when the anode electrode ink is applied to the electrolyte membrane with a slot nozzle and dried, and then the cathode electrode ink is applied as particles or fibers, the inverted electrode surface is brought into contact with a breathable base material and placed on a heat adsorption roll. In a fuel cell in which the electrolyte membrane is sucked through the breathable base material and the back sheet laminated on the electrolyte membrane is peeled off, and an electrode containing a catalyst of the cathode electrode is formed on the opposite side of the anode electrode. Provided is a method for manufacturing a membrane / electrode assembly.

In the present invention, an electrode ink is applied to an electrolyte film on which a back sheet is laminated and dried to form an electrode, and a first breathable protective base material is laminated on the electrode to form the first breathable protective group. The electrolyte film and the electrode are adsorbed by the heat adsorption drum through the material, the back sheet is peeled off, the electrode ink of the opposite electrode is applied to form the electrode, the breathable protective base material is recovered, and a new first electrode is collected. Provided is a method for manufacturing a film / electrode of a fuel cell, which comprises laminating a second breathable base material and winding the second breathable base material while protecting both electrodes.

As the electrode ink catalyst in the present invention, a core-shell type catalyst can be used.

According to the method for manufacturing a membrane electrode assembly of a fuel cell of the present invention, electrode ink can be directly applied to each surface of an electrolyte membrane even if it is delicate and has an ultra-thin electrolyte membrane of, for example, 15 microns or less. Further, in order to reduce the load on the electrolyte membrane, the electrode ink applied to the electrolyte membrane by heating and suction can volatilize 99% or more of the solvent amount instantly after wetting the electrolyte membrane, for example, within 3 seconds. It is ideal because it can improve the adhesion between the film and the electrode and minimize the interfacial resistance.

Further, in the present invention, the cathode electrode is not limited to the slot nozzle method, but is a spray method or a pulse-like spray belonging to the spray, which is a method of adding speed to the spray particles and is a trademark registration of M-Tech Smart Co., Ltd. When used alone or in combination with a slot nozzle, the adhesion of the catalyst to the electrolyte membrane can be further enhanced, and an electrode having ideal micropores, mesopores, and macropores can be formed. It should be noted that the air assist slot nozzle, the mist ejection slit nozzle, and the melt blown type spray nozzle can be used for spraying or pulse-like spraying.

Further, the present invention is not limited to a single nozzle head, and a plurality of heads can be arranged in series in the moving direction of the electrolyte membrane and laminated as a thin film. In particular, by using an air assist slot nozzle, a mist ejection slit nozzle, or a melt-blown nozzle head, the amount of electrodes in one layer per square centimeter can be adjusted to 0.01 to 0.3 milligrams. For example, a thin film of 2 to 30 layers of electrode ink can be used. It can also be laminated. The coating amount per layer can be reduced by combining with a heat adsorption drum or the like, but in order to further reduce the coating amount per layer, for example, carbon supporting a platinum catalyst, an electrolyte solution, an alcohol solvent, or water can be used. The solid content of the electrode ink composed of alcohol can be 10% or less by weight, for example 3% or less.

The merit of setting the solid content concentration as described above is that the thinner the film is and the more the layer is laminated, the less the load of the solvent shock of the electrolyte membrane is reduced and the more uniform the coating amount per unit area is, which leads to the improvement of the performance of the fuel cell.

Further, in the present invention, the electrolyte membrane is heated at 50 to 120 ° C., for example, through a microporous breathable base material, for example, dust-free paper or a breathable plastic film, for example, a commercially available inexpensive vacuum degree of about -60 kPa. Since it can be sucked by the vacuum pump of, it is possible to manufacture a film / electrode assembly that does not damage the electrolyte membrane and has no defects. It is economical to use the breathable substrate by wrapping it around a heat adsorption drum. Further, the adhesive is scattered in a porous shape using gravure rolls or the like on both sides other than the electrode forming portion of the electrolyte membrane, and a masking base material hollowed out to the electrode size is attached and moved to move the slot nozzle. An accurate electrode pattern can be formed by using not only the spray method but also. The masking base material is particularly useful for a spray method for atomizing electrode ink.

The surface of the heat adsorption roll can be manufactured by forming many holes having a diameter of 0.1 to 1 mm in a cylinder such as stainless steel at a pitch of 1 to 3 mm, for example, in a staggered pattern. Innumerable drilling can usually be done with a laser, electron beam, or the like. In order to make the adsorption distribution more uniform even with large holes or coarse pores, dust-free paper or porous film such as micrometer order can be wrapped around the heat adsorption drum and fixed to the surface of the drum. .. For example, it is economical because a heating and adsorption drum can be manufactured at low cost by winding a plurality of layers or by preparing a plurality of breathable base materials and laminating fine ones in order from a coarse one. Moreover, when a breathable base material on the order of micrometer or nanometer is used, it has the same effect as a heating adsorption drum on the order of micrometer or nanometer, so the cost performance is excellent in terms of performance. Alternatively, they are not limited to singular or plural, and can be unwound together with the electrolyte membrane and used for winding.

According to the present invention, the electrode ink is directly applied to an electrolyte film which is easily deformed and difficult to handle due to an ultra-thin film unexpected at the time of filing a patent application for a liquid coating and drying method of JP-A-2004-351413. A film / electrode assembly with stable quality can be manufactured by laminating.

As described above, according to the present invention, even if the electrode ink is directly applied to the delicate electrolyte, an ideal film-electrode interface can be obtained, and a high-quality film / electrode assembly and thus a fuel cell can be manufactured.

FIG. 5 is a schematic cross-sectional view of the arrangement of a heating (adsorption) roll, a small diameter roll, an electrolyte membrane, and a slot nozzle according to an embodiment of the present invention. FIG. 5 is a schematic cross-sectional view relating to a combination of a heating (adsorption) roll, a small diameter roll, an electrolyte membrane and a slot nozzle according to an embodiment of the present invention. FIG. 5 is a schematic cross-sectional view regarding the arrangement of a heating (adsorption) roll, an electrolyte membrane, a small diameter roll, a slot nozzle, and the like according to the embodiment of the present invention and a moving direction of a breathable base material and the like. FIG. 5 is a schematic cross-sectional view of an inverted electrolyte membrane and other components for forming a second electrode according to an embodiment of the present invention. It is a schematic cross-sectional view of the moving direction of the electrolyte membrane etc. of the application edition of the second electrode formation of the embodiment of this invention. It is a schematic sectional drawing of the membrane-electrode assembly which concerns on embodiment of this invention.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. It should be noted that the following embodiments are merely examples for facilitating the understanding of the invention, and excludes addition, substitution, modification, etc. that can be carried out by those skilled in the art within a range that does not deviate from the technical idea of the present invention. is not it.

The drawings schematically show preferred embodiments of the present invention.

In FIG. 1, a small-diameter roll 4 having a diameter smaller than that of the heat-adsorption drum 1 is provided upstream of the heat-adsorption drum 1, and the electrolyte membrane 2 unwound by the unwinding device 5 passes between the small-diameter roll 4 and the heat-adsorption drum 1 via the nip roll 10. An electrode ink (not shown) is applied on the OFF roll by the slot nozzle 3 and wound as a film / electrode assembly by the downstream winding device 6. A micrometer-order breathable substrate (not shown) can be wound in one or more layers on the heat adsorption drum. An electrode having an opposite electrode may be formed on the electrolyte membrane. Further, the application to the electrolyte membrane by the slot nozzle 3 may be an ON roll on the small diameter roll 4 or an OFF roll before and after the small diameter roll up to the heat adsorption roll. Ideally, if it is performed on the OFF roll just before the heat adsorption drum, heat adsorption starts almost at the same time as application, so it is also ideal from the aspect of drying. In particular, when performing with an OFF roll, it is desirable that a tension of 20 to 80 Newton is applied to the electrolyte membrane. Since the open / close valve mechanism in the slot nozzle can be cleanly cut by making it a suckback type, a rectangular or square electrode pattern can be formed. Further, when it is desired to provide a plurality of patterns orthogonal to the moving direction, it is convenient to assemble shims formed to desired dimensions.

FIG. 2 is a diagram in which a plurality of small diameter rolls (14, 14') are installed in the configuration of FIG. The slot nozzle 13 may be arranged on the small diameter rolls 14, 14', or on the front and rear, OFF rolls. Further, the small diameter roll may be heated.

In FIG. 3, the electrode ink is applied to the electrolyte membrane 32 by the slot nozzle 33 with the ON roll on the small diameter roll 34 to form the electrode pattern 205. The protective base material 38 is unwound on the electrode 205 dried on the heat adsorption roll 31 by the protective base material unwinding device 39, laminated on the electrolyte membrane 32 and the electrode 205, and wound up as a composite by the winding device 36. The protective base material may be a breathable base material, and the protective base material is the cheapest in terms of cost, although the material, type, and shape are not limited as long as the first electrode is formed in advance and the second electrode is formed. , The electrode may be selected from those that are not transferred or those that are difficult to transfer.

In FIG. 4, the back sheet 165 is peeled off upstream of the electrolyte membrane 42 on which the first electrode is formed, and the back sheet winding device 102 winds the back sheet 165. Electrode ink is applied to detect the position where the first electrode is formed on the opposite surface with the detection sensor and to form the second electrode with the slot nozzle 43. The breathable base material 138 that protects the first electrode and moves on the heat adsorption drum is wound by the breathable base material winding device 101. The electrolyte membrane on which the first and second electrodes are formed is wound by the winding device 46 together with the new protecting base material 148. The protective base material may be a breathable base material, but a base material that does not affect the electrode surface and has a low cost should be selected.

FIG. 5 is a diagram in which the second electrode is formed by a spray instead of the slot nozzle. Except for the spray, the configuration is almost the same as in FIG. Use the electrode ink as mist and apply it together with the air curtain along the electrode ink flowing out from the mist ejection slit nozzle or slot nozzle. For sprays other than the air assist application method, install a mask with almost the same shape as the first electrode pattern. Should be. The first electrode is formed by increasing the slot nozzle speed, and the second electrode is effective in terms of performance because it is compatible with the cathode and a microporous shape can be formed on the electrode by spraying.

FIG. 6 is a cross-sectional view in which a first electrode 305 and a second electrode 305'are formed on both sides of the electrolyte membrane 302, and a protective base material 348 is laminated on the second electrode.

According to the present invention, a membrane / electrode assembly for a PEFC fuel cell can be manufactured at high speed and with high quality.

1,11,31,41,51 Heating (heat adsorption) drum 2,12,32,42,302 Electrolyte membrane 3,13,33,43 Slot nozzle 4,14,14', 34,34', 44 Small diameter roller 5,25,35,45,55 Electrolyte membrane unwinding device 6,26,36,46,56 Electrolyte membrane unwinding device 7,17 CCM
10, 20, 30, 40, 50 Nip roll 38, 138, 148, 248, 348 Electrode protecting base material (breathable base material)
39, 49, 59 Electrode protecting group unwinding device 101,201 Electrode protecting group winding device 102, 202 Back sheet winding device 203 Spray coating head 205 Electrode 305 First electrode 305 ′ Second electrode

Claims (9)

A method for manufacturing a fuel cell, which is a method in which a long electrolyte film for a fuel cell is continuously or intermittently moved, and electrode ink is applied to at least one side of the electrolyte film with a slot nozzle to form an electrode. , A step of providing a heat adsorption roll that heats and adsorbs the electrolyte membrane coated with the electrode ink, and a step of providing at least one roll having a diameter smaller than that of the heat adsorption roll in the vicinity of the heat adsorption roll upstream of the heat adsorption roll. A method for manufacturing a fuel cell, which comprises a step of applying electrode ink with a slot nozzle between the small diameter roll and the contact of the electrolyte membrane with the heated adsorption roll, and manufacturing the membrane / electrode assembly. The method for manufacturing a fuel cell according to claim 1, wherein the heating adsorption roll is a heating roll and moves while applying a tension of 20 to 80 Newton to the electrolyte membrane. The method for manufacturing a fuel cell according to claim 1, wherein the heat adsorption roll is a heat adsorption belt. The method for producing a fuel cell according to claim 1, wherein a tension of 20 to 80 Newton is applied to the electrolyte membrane before and after the small diameter roll, and the electrode ink is applied on the off-roll before and after the small diameter roll. The method for manufacturing a fuel cell according to claim 1, wherein the slot nozzle is an air assist slot nozzle or a mist ejection slit nozzle, and the distance between the electrolyte membrane and the nozzle head is set to 0 to 10 mm. The roundness of the heating adsorption roll or the heating roll is ± 50 micrometer or less, and the electrode ink is applied on the off-roll immediately before the electrolyte film comes into contact with the heating adsorption roll or the heating roll. The method for manufacturing a fuel cell according to claim 1 or 2. An electrode having a desired pattern is formed on both sides of the electrolyte membrane, and at least one protective base material is provided so that the electrodes do not come into contact with each other during winding so that the electrodes are not sucked on the heat adsorption roll. The method for producing a fuel cell according to claim 1 or 5, wherein the protective substrate is interposed and has air permeability. Before the tensioned electrolyte membrane with backsheet comes into contact with the heated adsorption roll, the anode electrode ink is applied with a slot nozzle and dried, and then the cathode electrode ink is applied in the form of particles or fibers. On the heat-adsorption roll, the electrolyte membrane is sucked through the breathable substrate, and the back sheet laminated on the electrolyte membrane is peeled off, and on the opposite side of the anode electrode. A method for manufacturing a fuel cell, which comprises forming an electrode containing a catalyst of a cathode electrode. In a fuel cell, the anode electrode ink is applied with a slot nozzle and dried until the tensioned electrolyte membrane with a back sheet comes into contact with the heated adsorption roll, and then the cathode electrode ink is applied in the form of particles or fibers. , The step of bringing the inverted electrode surface into contact with the breathable base material, sucking the electrolyte membrane through the breathable base material on the heat adsorption roll, and peeling off the back sheet laminated on the electrolyte membrane, and the anode. A fuel cell characterized in that an electrode containing a catalyst for the cathode electrode is formed on the opposite side of the electrode.

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