JPH09180740A - Solid high-molecular fuel cell and manufacture and device thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To evenly form a thin high-molecular electrolyte film with excellent adhesiveness so as to provide a solid high-molecular fuel cell having high performance by screen-printing one surface of an electrode with the solution of high- molecular electrolyte. SOLUTION: An electrode 21, which is formed by forming a catalyst layer 22 on a gas diffusion layer, is placed in a recessed part of a supporting base 19 having a peripheral edge 20. As this gas diffusion layer, a carbon paper or a water repellent carbon paper is desirable. The catalyst layer 22 contains the catalyst, which is composed of the carbon powder carrying platinum, and the electrolyte, and furthermore, it desirably contains the water repellent agent at need. This electrode 21 is screen-printed with the printing liquid 25 through a squeegee 24 by using a screen 23, which is formed of a film 27 and a screen part S, so as to manufacture an electrolyte film 26. As the printing liquid 25, the printing liquid at the appropriate viscosity, which is obtained by using the high-molecular electrolyte composed of the resin of perfluorocarbon sulfonic acid, is used. After drying this electrolyte film 26, other electrode is provided thereon to obtain a cell.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid polymer type fuel cell, a manufacturing method and an apparatus therefor, and more specifically, a solid polymer type electrolyte membrane having a thin solid polymer electrolyte membrane and high cell performance. The present invention relates to a fuel cell, its manufacturing method and device.

[0002]

2. Description of the Related Art A polymer electrolyte fuel cell is characterized in that an ionic conductor, that is, an electrolyte is a solid and a polymer. The solid polymer electrolyte is specifically an ion exchange resin or the like. Is used, and both electrodes of a negative electrode (anode = fuel electrode) and a positive electrode (cathode = oxygen electrode or air electrode) are arranged with the polymer electrolyte membrane sandwiched therebetween. For example, hydrogen gas as a fuel is placed on the negative electrode side, In addition, electricity is generated by supplying oxygen or air to the positive electrode side to cause an electrochemical reaction.

Although there are various modes of this device, FIG. 1 is a schematic view for explaining one mode of this polymer electrolyte fuel cell. In FIG. 1, 1 is a polymer electrolyte membrane, 2 is a cathode electrode (positive electrode = oxygen electrode or air electrode), 3
Is an anode electrode (negative electrode = fuel electrode), and the polymer electrolyte membrane 1 is disposed in contact with the opposing positive and negative electrodes 2 and 3. Further, 4 is a cathode electrode side current collector, 5 is an anode electrode side current collector, and the positive and negative electrodes 2 and 3 respectively.
Is in contact with

Of these, the electrode 2 of the cathode electrode side current collector 4
A groove for supplying oxygen or air is provided on the side, a groove for supplying fuel (hydrogen etc.) is provided on the side of the electrode 3 of the anode electrode side current collector 5, and a groove for the positive electrode side current collector 4 is The groove of the negative electrode side current collector 5 communicates with the oxygen or air supply pipe 6 and the fuel (hydrogen or the like) supply pipe 7. Further, 8 is a cathode terminal plate provided in contact with the positive electrode side current collector 4, 9 is an anode terminal plate provided in contact with the negative electrode side current collector 5, and power is supplied through these during operation of the battery. Is taken out.

Reference numeral 10 denotes an upper frame body (upper frame), 11 denotes a lower frame body (lower frame).
0 and 11 from the polymer electrolyte membrane 1 to the cathode terminal plate 8
And the battery body up to the anode terminal plate 9 is fixed. A packing (gasket) is provided between the upper and lower frames 10 and 11 so as to surround the periphery of the battery main body from the polymer electrolyte membrane 1 to the cathode terminal plate 8 and the anode terminal plate 9.
12 is provided, thereby tightly fixing and sealing the peripheral portion of the battery body, and particularly gas-sealing the polymer electrolyte membrane 1 and the positive and negative electrodes 2 and 3. FIG. 1
Inside, 13 and 14 are cooling water supply pipes, which communicate with the grooves (closed passages) provided on the inner surfaces of the upper frame body 10 and the lower frame body 11, respectively, and the cooling water supplies the cooling water to the cathode terminal plate 8. The cooling is performed indirectly from the back surface and the back surface of the anode terminal plate 9.

[0006] The above is the case of a single battery body,
In some cases, two or more battery bodies are stacked. In this case, it is necessary to interpose a separator between each of the two or more battery bodies, and also to provide a groove for cooling water, etc., as appropriate, but a packing is provided to surround the peripheral edge of the battery body. Basically, in the case of the single battery body described above, including tightly fixing and sealing the peripheral portion of the body and gas-sealing the polymer electrolyte membrane 1 and both the positive and negative electrodes 2 and 3. Is the same as. In this case, the packing 12 and the like are tightened via the separator.

By the way, the cell body in such a polymer electrolyte fuel cell has a negative electrode (anode = anode) fixed and abutting with the polymer electrolyte membrane sandwiched from both sides as described above.
A fuel electrode) and a positive electrode (cathode = oxygen electrode or air electrode), and FIG. 2 is a schematic diagram showing an example of this configuration.
In FIG. 2, reference numerals 15 and 16 are a gas diffusion layer and a catalyst layer that respectively configure the positive electrode 2 (air electrode), and 17 and 18 are a gas diffusion layer and a catalyst layer that respectively configure the negative electrode 3 (fuel electrode). As shown, the positive electrode 2 is sandwiched by the polymer electrolyte membrane 1.
(= Oxygen electrode or air electrode) and the negative electrode 3 (= fuel electrode) are fixed.

In this case, the fixing is performed by arranging the positive and negative electrodes so that their catalyst layer sides (16 and 18) are in contact with the polymer electrolyte membrane surface, and the fixing is usually performed by hot pressing. However, when using a pre-formed polymer electrolyte membrane in constructing such a battery body, the thickness of the polymer electrolyte membrane depends on the handling problems of itself and the heat generated by hot pressing when abutting and fixing the electrodes. It cannot be made too thin because of the influence. Further, with such a method, the contact surface between the electrode and the electrolyte membrane is two-dimensional, and high battery performance cannot be obtained.

[0009]

Therefore, in the present invention,
As described above, instead of preliminarily forming a polymer electrolyte membrane separately from the electrode, by forming a polymer electrolyte membrane on the electrode surface, the above problems or drawbacks are improved,
It is an object of the present invention to provide a solid polymer electrolyte fuel cell, which is improved and can form a thin polymer electrolyte membrane, and has high cell performance, a method for manufacturing the same, and an apparatus for producing the same.

[0010]

[Means for Solving the Problems] That is, the present invention provides a polymer electrolyte fuel cell of a type in which a polymer electrolyte membrane is arranged between positive and negative electrodes, the polymer electrolyte membrane being higher than one surface of the electrode. It is intended to provide a polymer electrolyte fuel cell characterized in that a solution of a molecular electrolyte is formed into a film by screen printing.

The present invention also provides a method for producing a polymer electrolyte fuel cell in which a polymer electrolyte membrane is arranged between positive and negative electrodes, and a polymer electrolyte solution is applied to the electrode surface of the polymer electrolyte membrane. Provided is a method for producing a polymer electrolyte fuel cell, which comprises coating by screen printing to form a membrane, and the present invention further provides a polymer electrolyte membrane of a type in which a polymer electrolyte membrane is disposed between positive and negative electrodes. A fuel cell manufacturing apparatus, characterized in that the polymer electrolyte membrane is applied to the electrode surface by screen printing using a screen and a squeegee to form a membrane. An apparatus for producing a polymer electrolyte fuel cell is provided.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION As an electrolyte membrane for a polymer electrolyte fuel cell, a polystyrene membrane which has been gradually improved and improved from the initial condensation synthetic membrane of phenolsulfonic acid and formaldehyde and has been partially sulfonated,
Membrane sulfonated after cross-linking styrene-divinylbenzene to a fluorocarbon matrix,
, A film containing no αC—H bond, a polymer film of trifluorostyrene sulfonic acid, a film obtained by grafting trifluoroethylene on a fluorocarbon matrix, a perfluorocarbon sulfonic acid resin film, and the like have been proposed.

The present invention is not limited to these exemplified electrolyte membranes and can be applied regardless of the type of polymer electrolyte membrane, but is particularly effectively applied to perfluorocarbon sulfonic acid type resin membranes. be able to. This perfluorocarbon sulfonic acid-based resin film is mainly used at present because it has excellent electrical characteristics, is extremely stable chemically and physically, and is mechanically large. This film is formed in advance and is used as a film having a thickness of about 50 to 200 μm (when the thickness is less than about 80 μm, it is not necessarily sufficient in terms of strength, etc.), and even with this thickness, the electric resistance per unit area is 0. 1 to 0.5Ω is so small as not to be a main cause of the internal resistance of the battery, but according to the present invention, it is possible to form a film thinner than the lower limit of the film thickness of 50 μm. Even if the thickness is set to about 10 μm, the influence of heat due to hot pressing can be reduced and effective battery characteristics can be obtained.

Further, as the above-mentioned electrode in the present invention,
Any electrode that can be applied as an electrode for a polymer electrolyte fuel cell can be used. In particular, when a perfluorocarbon sulfonic acid-based resin is used as the material for the polymer electrolyte membrane, an electrode having a catalyst layer formed on the gas diffusion layer is preferably used. This gas diffusion layer also serves as a base material of the electrode itself, and as this material, a porous paper or sheet made of various materials (in this specification, both are appropriately referred to as "paper"), Alternatively, these can be appropriately water repellent and used, but carbon paper or water repellent carbon paper can be preferably used. Among these, the water repellent carbon paper is obtained by impregnating a carbon paper having a predetermined porosity and thickness with a polytetrafluoroethylene-based dispersion and then heat-treating it to make it water repellent. Here, the polytetrafluoroethylene-based polymer is meant to include not only polytetrafluoroethylene (PTFE) but also tetrafluoroethylene-hexafluoropropylene copolymer and other derivatives thereof.

The catalyst layer contains a water repellent agent in addition to the catalyst powder and the electrolyte, or both of these components. With these materials, a pressure filtration method or other method is applied to the surface of the gas diffusion layer. Are formed in layers. As the catalyst powder, platinum black powder, platinum alloy powder, carbon black powder supporting platinum or palladium, palladium black powder and the like can be used. As the electrolyte, various ion exchange resins and the like can be used. In particular, when using a perfluorocarbon sulfonic acid type resin membrane as the solid polymer electrolyte membrane, use a perfluorocarbon sulfonic acid resin type of the same type. Is preferred. The water repellent agent is not particularly limited, but is preferably a polytetrafluoroethylene-based polymer. Here, the polytetrafluoroethylene-based polymer is meant to include tetrafluoroethylene-hexafluoropropylene copolymer and other derivatives thereof in addition to polytetrafluoroethylene.

In the present invention, for example, a printing liquid containing a polymer electrolyte is printed and applied by screen printing on the surface of the above-mentioned electrode on the catalyst layer side to form a film. The viscosity of the printing liquid is sufficient if it has a viscosity such that the film thickness and the like can be controlled by a squeegee without flowing and diffusing after the application, but it is preferably 1000 to 10
It is about 000 cp (centipoise).

FIG. 3 is a schematic view for explaining the production mode of the polymer electrolyte membrane by the screen printing type coating method of the present invention. In FIG. 3A, 19 is a support table on which an electrode 21 is placed, 21 is an electrode on which an electrolyte membrane is printed,
Reference numeral 22 indicates the catalyst layer. The area of the electrolyte membrane is usually required to be larger than the area of the electrode surface. Therefore, the support base 19 has the same recess as the electrode 21 and the upper surface of the electrode 21 on the catalyst layer 22 side mounted in this recess. And a peripheral portion 20 configured in a level. As a result, the electrolyte membrane is formed on the surface of the electrode 21 on the catalyst layer 22 side and the surface of the peripheral portion 20 of the support 19, and is adhered to the surface of the electrode on the catalyst layer side in close contact with each other.

23 is a screen, 24 is a squeegee, and 25
Is a printing liquid serving as an electrolyte membrane, 26 is an electrolyte membrane formed by printing, and an arrow (→) in FIG. 3A indicates a printing direction by operating the squeegee 24. FIG.
3B is a plan view of the screen 23, and FIG.
In the figure, 27 is a plate film, that is, a masked screen, and S is an exposed screen portion. Although the exposed screen portion S is shown as a rectangle in FIG. 3B,
The shape and size (width) of the exposed screen portion S are set according to the desired shape and size (width) of the electrolyte membrane. The electrolyte membrane 26 printed with the printing liquid 25 is formed in the exposed space S.

As an operation mode of this apparatus, the printing liquid 25 is supplied between the screen 23 and the squeegee 24 as shown in the figure, and the squeegee 24 is moved in the direction of the arrow (→) in FIG. 3A. As a result, the electrolyte membrane 26 having a predetermined thickness is uniformly printed and formed on the electrode surface 22. Printing liquid 25
Are printed on the electrode surface 22 in this way, and the electrolyte membrane 2
However, for this reason, the printing liquid 25 needs to have a predetermined viscosity, and this viscosity is 1,000 to 10,000 as described above.
It can be applied in the order of cp (centipoise). Further, according to the present invention, by selecting the thickness of the screen 23, it is possible to freely form an electrolyte membrane having a desired thickness ranging from 10 μm to 100 μm.

Next, an aspect of a specific procedure of the present invention is as follows (1) to (5).
(1) The electrolyte solution (solvent = alcohol, etc.) is heated to a temperature of 50.
Viscosity is 1000 cp
Prepare so that the amount is at least as good. (2) The electrode (air electrode) prepared in advance is placed on the screen printing device, and the electrolyte solution obtained in (1) is put on the screen 23. The squeegee 24 is moved onto the screen 23, and the electrolyte solution is applied by printing so as to have a thickness of, for example, about 30 to 100 μm. (3) The electrode printed with the electrolyte solution is processed by vacuum drying or the like to remove the solvent (alcohol, etc.). (4) In this way, an electrolyte membrane is formed on one surface thereof, and an electrode (fuel electrode) prepared in advance is brought into contact with the electrolyte membrane side of the dried electrode and pressed to obtain a battery.

[0021]

EXAMPLES Examples of the present invention will be described below, but it goes without saying that the present invention is not limited to these examples. As the apparatus used, the apparatus shown in FIG. 3 was used.

(1) First, the electrode has a surface area of 100
cm ² (10 cm × 10 cm), 80% porosity, 0.4 mm thick carbon paper with neoflon (tetrafluoroethylene-hexafluoropropylene copolymer,
NAFIO as an electrolyte on carbon paper which is made water repellent by the dispersion of Daikin Industries, Ltd.)
N-117 (perfluorocarbon sulfonic acid resin, D
A product prepared by depositing a suspension obtained by adding a dispersion of polytetrafluoroethylene to catalyst particles (carrier: carbon black) supporting 50% by weight of platinum coated with an alcohol solution of u Pont Co., Ltd. used.

(2) Next, a commercially available ethanol solution of perfluorocarbon sulfonic acid resin as a polymer electrolyte is heated to a temperature of 50 ° C. to evaporate the solvent, and the viscosity thereof becomes 200.
It was prepared to be about 0 cp. (3) The electrode (air electrode) prepared in advance in (1) above is placed in the recess of the support base 19 of the screen printing apparatus shown in FIG.
The electrolyte solution obtained in (2) above was put in 3. Move the squeegee 24 on the screen 23 and apply the electrolyte solution to an area of 1
It was applied by printing so as to have a thickness of 44 cm ² (12 cm × 12 cm) and a thickness of about 50 μm.

(4) The electrode printed with the electrolyte solution in the above (3) was vacuum dried to remove the solvent ethanol by evaporation. (5) Thus, a polymer electrolyte membrane is formed on one surface thereof, and the electrode (fuel electrode) prepared in advance as in the above (1) is brought into contact with the surface of the dried electrode on the electrolyte membrane side, and the temperature is 140 ° C. After pressing under a pressure of 100 kgf / cm ² for 60 seconds, this was assembled and set in a fuel cell frame as shown in FIG. 1, and a lead wire, a gas pipe, etc. were connected to obtain a test battery for an example. .

Comparative Example On the other hand, a solid polymer electrolyte membrane having a thickness of 80 is formed between the two electrodes prepared as described in (1) above.
A μm perfluorocarbon sulfonic acid resin membrane was sandwiched by bringing the catalyst layers of both electrodes into contact with the membrane surfaces, and pressed at a temperature of 140 ° C. under a pressure of 100 kgf / cm ² for 60 seconds in the same manner as in the example. This was assembled and set in a fuel cell frame as shown in FIG. 1, and a lead wire, a gas pipe and the like were connected to obtain a comparative test battery.

Using the various test batteries produced as described above, hydrogen was used as the fuel, and this was supplied to the anode side, while air was supplied to the cathode side. The supply pressure of both gases is 2 atm, and hydrogen is 95 ° C.
Humidify the air at 80 ° C and keep the battery temperature at 80 ° C.
The measurement was performed by keeping the temperature at ℃. FIG. 4 shows the relationship between the cell density and the current density measured for each of the above test batteries.

As shown in FIG. 4, in the comparative test battery, the cell voltage decreases with a considerable slope as the current density increases, but in the test battery of the embodiment, the decreasing tendency is extremely slow. It can be seen that high battery performance is obtained. This effect according to the present invention is based on the fact that the electrolyte membrane is thin and the adhesion of the polymer electrolyte membrane to the electrode surface is good (further, it is presumed that the contact surfaces of both are made three-dimensional. Thus, according to the present invention, the battery characteristics can be improved more effectively.

[0028]

As described above, according to the present invention, the thickness of the polymer electrolyte membrane can be formed as thin as about 20 μm or 30 μm, and the adhesion of the polymer electrolyte membrane to the electrode surface can be improved. Since it is good, a battery having higher performance can be obtained. Further, not only can the film thickness be thin and uniform even in a large area, but the desired optimum thickness of the electrolyte membrane can be freely determined.

[Brief description of the drawings]

FIG. 1 is a schematic view illustrating one embodiment of a polymer electrolyte fuel cell.

FIG. 2 is a diagram showing a battery main body in FIG.

FIG. 3 is a diagram showing one embodiment of a battery manufacturing method and device according to the present invention.

FIG. 4 is a diagram showing the relationship between the measured current density and cell voltage of each test battery manufactured in Examples and Comparative Examples.

[Explanation of symbols]

 1 Polymer Electrolyte Membrane 2 Cathode Electrode (Positive Electrode) 3 Anode Electrode (Negative Electrode) 4, 5 Current Collector 6 Air Supply Pipe 7 Hydrogen Supply Pipe 8, 9 Terminal Plate 10, 11 Frame (Frame) 12 Packing 13, 14 Cooling Water supply pipe 15 Gas diffusion layer of positive electrode 2 (air electrode) 2 16 Catalyst layer of positive electrode 2 (air electrode) 17 Gas diffusion layer of negative electrode 3 (fuel electrode) 18 Catalyst layer of negative electrode 3 (fuel electrode) 19 Electrode 21 The support base 20 on which the substrate is mounted 21 The peripheral portion of the support base 21 The electrode on which the electrolyte membrane is printed 22 The catalyst layer of the electrode 21 23 The screen 24 The squeegee 25 The printing liquid used as the electrolyte membrane 26 The electrolyte membrane formed by printing 27 The plate membrane = Masked screen) S Exposed screen part

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[Procedure amendment]

[Submission date] April 16, 1996

[Procedure amendment 1]

[Document name to be amended] Drawing

[Correction target item name] All figures

[Correction method] Change

[Correction contents]

[Fig. 1]

FIG. 2

[Fig. 3]

[Fig. 4]

Claims (9)

[Claims] 1. A polymer electrolyte fuel cell of the type in which a polymer electrolyte membrane is arranged between positive and negative electrodes, wherein the polymer electrolyte membrane is formed by screen printing a solution of the polymer electrolyte on one surface of the electrode. A polymer electrolyte fuel cell, characterized by comprising: 2. The polymer electrolyte fuel cell according to claim 1, wherein the polymer electrolyte is a perfluorocarbon sulfonic acid type resin. 3. An electrode comprising the gas diffusion layer on which a catalyst layer containing (A) catalyst powder and an electrolyte or (B) a catalyst layer containing a catalyst powder, an electrolyte and a water repellent agent is formed. The polymer electrolyte fuel cell according to claim 1 or 2. 4. The polymer electrolyte fuel cell according to claim 3, wherein the gas diffusion layer is a gas diffusion layer made of carbon paper or water repellent carbon paper. 5. The polymer electrolyte fuel cell according to claim 3, wherein the catalyst powder is carbon powder supporting platinum. 6. A method for producing a polymer electrolyte fuel cell of the type in which a polymer electrolyte membrane is arranged between positive and negative electrodes, the polymer electrolyte membrane being applied to a surface of the polymer electrolyte solution by screen printing. A method for producing a polymer electrolyte fuel cell, which comprises coating and forming a film. 7. The method for producing a polymer electrolyte fuel cell according to claim 6, wherein the polymer electrolyte is a perfluorocarbon sulfonic acid resin. 8. A polymer electrolyte fuel cell manufacturing apparatus in which a polymer electrolyte membrane is arranged between positive and negative electrodes, wherein a polymer electrolyte solution is screened against the electrode surface of the polymer electrolyte membrane. An apparatus for producing a polymer electrolyte fuel cell, characterized by being applied by screen printing using a squeegee to form a film. 9. The apparatus for producing a polymer electrolyte fuel cell according to claim 8, wherein the polymer electrolyte is a perfluorocarbon sulfonic acid-based resin.