JP2002110182A - Gas-diffusion electrode and method for making the same, and, electrochemical device and method for making the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gas-diffusion electrode wherein the gas permeability is enhanced. SOLUTION: The gas-diffusion electrode of this invention comprises a carbon sheet with a catalyst layer formed on one of its surfaces, and with a plularity of through holes formed from a surface to the other surface. With these through holes, the gas permeability is enhanced, so that it is possible to improve significantly the energy efficiency of an electrochemical device which uses the gas- diffusion electrode.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a gas diffusion electrode, a method for manufacturing the same, and an electrochemical device and a method for manufacturing the same. More particularly, the present invention relates to a gas diffusion electrode with enhanced gas permeability, a method for manufacturing the same, and a method for manufacturing the same. The present invention relates to an electrochemical device using such an electrode and a method for manufacturing the same.

[0002]

2. Description of the Related Art Since the industrial revolution, fossil fuels such as gasoline and light oil have been widely used not only as energy sources for automobiles but also as energy sources for electric power production. The use of fossil fuels has enabled humankind to enjoy such dramatic improvements in living standards and the development of industry, but on the other hand, the planet has been threatened with serious environmental destruction, There is a possibility that fuel will be depleted, and a long-term stable supply will be questioned.

[0003] Therefore, hydrogen is contained in water, is inexhaustibly present on the earth, has a large amount of chemical energy per substance, and when used as an energy source, harmful substances and earth. Because it does not emit greenhouse gases, it is a clean alternative to fossil fuels, and
In recent years, it has attracted great attention as an inexhaustible energy source.

[0004] In particular, in recent years, research and development of an electric energy generator capable of extracting electric energy from hydrogen energy has been actively carried out. From large-scale electric power generation to on-site in-house electric power generation, and further for automobiles, The application as a power supply is expected.

[0005] An electric energy generator for extracting electric energy from hydrogen energy, that is, a fuel cell has a hydrogen electrode to which hydrogen is supplied and an oxygen electrode to which oxygen is supplied. Hydrogen supplied to the hydrogen electrode is
By the action of the catalyst, protons (protons) and electrons are dissociated, and the electrons are collected by the current collector of the hydrogen electrode, while the protons are carried to the oxygen electrode. The electrons collected at the hydrogen electrode are transferred to the oxygen electrode via a load. on the other hand,
Oxygen supplied to the oxygen electrode is combined with protons and electrons carried from the hydrogen electrode by the action of a catalyst to generate water. In this way, an electromotive force is generated between the hydrogen electrode and the oxygen electrode, and a current flows to the load.

[0006]

Generally, as the hydrogen electrode and the oxygen electrode, an electrode film having a catalyst layer formed on one surface is used, and hydrogen gas or oxygen gas (air) is applied from the other surface of these electrode films. ) Is supplied to generate electric energy. In order to efficiently generate electric energy, hydrogen gas supplied from the other surface of the hydrogen electrode is formed on one surface of the hydrogen electrode. It is necessary that the oxygen gas (air) supplied from the other surface of the oxygen electrode smoothly move to the catalyst layer formed on one surface of the oxygen electrode. is there.

[0007] Therefore, if the gas permeability of the hydrogen electrode and the oxygen electrode themselves is low, the ratio of the hydrogen gas or the oxygen gas that reaches the catalyst layer becomes low, and there is a problem that the efficiency of generating electric energy is reduced.

Accordingly, an object of the present invention is to provide a gas diffusion electrode having high gas permeability and a method for manufacturing the same.

Another object of the present invention is to provide a fuel cell having a high efficiency of generating electric energy by using a gas diffusion electrode having a high gas permeability, and a method for manufacturing the same.

[0010]

SUMMARY OF THE INVENTION The object of the present invention is as follows.
This is achieved by a gas diffusion electrode comprising a carbon sheet having a catalyst layer formed on one surface, and a plurality of through holes formed from the one surface to the other surface.

According to the present invention, since a plurality of through holes are formed from one surface of the carbon sheet to the other surface, a gas diffusion electrode having high gas permeability can be provided.

In a preferred embodiment of the present invention, the number of the through holes is 400 or more per 1 cm ² .

According to the preferred embodiment of the present invention, it is possible to sufficiently increase the gas permeability of the gas diffusion electrode.

In a further preferred aspect of the present invention, at least 2500 through holes are formed per 1 cm ² .

According to a further preferred embodiment of the present invention, the gas permeability of the gas diffusion electrode can be more sufficiently improved.

[0016] In a further preferred aspect of the present invention, the diameter of the through hole is 0.1 mm on the one surface.
mm or less.

According to a further preferred embodiment of the present invention, it is possible to increase the gas permeability while sufficiently maintaining the mechanical strength of the gas diffusion electrode itself. Further, according to a further preferred embodiment of the present invention, the possibility that the amount of the catalyst contained in the catalyst layer becomes insufficient is reduced.

In a further preferred aspect of the present invention, an opening diameter of the through hole on the one surface is smaller than an opening diameter on the other surface.

According to a further preferred embodiment of the present invention, it is possible to effectively guide oxygen gas or hydrogen gas to the catalyst layer and to prevent a decrease in the amount of catalyst contained in the catalyst layer.

In a further preferred aspect of the present invention, the catalyst layer is coated with a proton conductive material.

According to a further preferred embodiment of the present invention, since the proton conductive material is applied to the catalyst layer, the protons dissociated by the catalyst can be efficiently conducted.

According to the present invention, there is also provided a catalyst layer forming step of forming a catalyst layer on one side of a carbon sheet, and forming a plurality of through holes from the one side to the other side of the carbon sheet. And a method of manufacturing a gas diffusion electrode comprising a through hole forming step.

According to the present invention, by the through hole forming step,
Since a plurality of through holes are formed from one surface of the carbon sheet to the other surface, a gas diffusion electrode having high gas permeability can be manufactured.

In a preferred embodiment of the present invention, the step of forming a through hole is performed by piercing a needle from the other surface of the carbon sheet to the one surface.

According to a preferred embodiment of the present invention, since the through hole is formed by piercing a needle from the other surface of the carbon sheet to one surface, the formed through hole is wide on the other surface. It will open and will open narrowly on one side. This makes it possible to effectively guide the oxygen gas or the hydrogen gas to the catalyst layer, and to prevent a decrease in the amount of catalyst contained in the catalyst layer.

In a further preferred aspect of the present invention, the step of forming a catalyst layer is performed by applying a liquid containing a catalyst-supporting carbon to the one surface of the carbon sheet.

In a further preferred embodiment of the present invention, the liquid contains fibrous carbon.

According to a further preferred embodiment of the present invention, since the liquid to be applied contains fibrous carbon, it is possible to enhance the adhesion of the catalyst layer formed on one surface of the carbon sheet. Become.

According to another preferred embodiment of the present invention,
The catalyst layer forming step is performed by a vapor phase film forming method.

According to another preferred embodiment of the present invention,
The catalyst layer forming step is performed by a chemical wet method.

In a further preferred embodiment of the present invention, the method further comprises a coating step of coating a proton conductive material on the catalyst layer formed on the one surface of the carbon sheet.

According to a further preferred embodiment of the present invention, the proton conducting material is applied in the applying step, so that the protons dissociated by the catalyst can be efficiently conducted.

In a further preferred aspect of the present invention, the applying step is performed before the through-hole forming step.

According to a further preferred embodiment of the present invention, since the through holes are formed after the proton conductive material is applied in the coating step, the through holes are not blocked by the proton conductive material.

The object of the present invention also includes a gas diffusion electrode having a catalyst layer formed on one surface, and an electrolyte membrane attached to the one surface of the gas diffusion electrode. Is achieved by an electrochemical device, wherein a plurality of through holes are formed from the one surface to the other surface.

According to the present invention, since a plurality of through holes are formed in the gas diffusion electrode, it is possible to provide an electrochemical device having high gas permeability of the gas diffusion electrode and therefore high energy efficiency.

[0037] In a preferred embodiment of the present invention, the electrochemical device is a fuel cell.

[0038] In another preferred embodiment of the present invention, the electrochemical device is an air battery.

The object of the present invention is also an oxygen electrode having a catalyst layer formed on one surface, a fuel electrode having a catalyst layer formed on one surface, and a fuel electrode having a catalyst layer formed on one surface. A proton conductor portion sandwiched between the one surfaces of the electrodes, and the oxygen electrode and the fuel electrode each have a plurality of through holes formed from the one surface to the other surface. This is achieved by a fuel cell characterized in that:

According to the present invention, since a plurality of through holes are formed in both the oxygen electrode and the fuel electrode, a fuel cell having high gas permeability of the oxygen electrode and the fuel electrode, and thus having high energy generation efficiency can be obtained. Can be provided.

In a preferred embodiment of the present invention, the through holes are formed in both the oxygen electrode and the fuel electrode, and the formation density of the through holes in the oxygen electrode and the through hole in the fuel electrode are different from each other. The formation density is different.

According to a further preferred embodiment of the present invention, even when the gas permeability required for the oxygen electrode and the fuel electrode are different, it is possible to provide the oxygen electrode and the fuel electrode with optimal gas permeability. Becomes possible.

In a further preferred aspect of the present invention, the formation density of the through holes in the oxygen electrode is higher than the formation density of the through holes in the fuel electrode.

According to a further preferred embodiment of the present invention, even if the supply of oxygen (air) on the oxygen electrode side is spontaneous aspiration, that is, the air is supplied to the oxygen electrode without pressurizing, the penetration through the oxygen electrode is prevented. Since the density of the holes is high, oxygen (air) is sufficiently supplied to the catalyst layer.

In a further preferred aspect of the present invention, the through hole is formed in both the oxygen electrode and the fuel electrode, and the diameter of the through hole in the oxygen electrode and the diameter of the through hole in the fuel electrode are different from each other. Different in diameter.

According to a further preferred embodiment of the present invention, even if the gas permeability required for the oxygen electrode and the fuel electrode are different, it is possible to provide the oxygen electrode and the fuel electrode with optimal gas permeability. Becomes possible.

In a further preferred aspect of the present invention, the diameter of the through hole in the oxygen electrode is larger than the diameter of the through hole in the fuel electrode.

According to a further preferred embodiment of the present invention, even when the supply of oxygen (air) on the oxygen electrode side is spontaneous aspiration, the oxygen (air) is formed due to the high density of through holes formed in the oxygen electrode. It will be sufficiently supplied to the catalyst layer.

The object of the present invention is also a catalyst layer forming step of forming a catalyst layer on one surface of a carbon sheet, and forming a plurality of through holes from the one surface to the other surface of the carbon sheet. This is achieved by a method for manufacturing an electrochemical device, wherein a gas diffusion electrode is produced by a through-hole forming step, and an electrolyte membrane is attached to the catalyst layer of the gas diffusion electrode.

According to the present invention, by the through hole forming step,
Since a plurality of through holes are formed in the gas diffusion electrode, gas permeability of the gas diffusion electrode is high, and therefore, an electrochemical device having high energy efficiency can be manufactured.

[0051]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is a diagram showing a schematic configuration of a fuel cell to be manufactured according to a preferred embodiment of the present invention.

As shown in FIG. 1, the fuel cell according to this embodiment has an oxygen electrode 1, a hydrogen electrode 2 as a fuel electrode, and a proton membrane as an electrolyte membrane sandwiched between the oxygen electrode 1 and the hydrogen electrode 2. And a conductor portion 3. Oxygen electrode 1
Is composed of an electrode substrate 4 made of a carbon sheet and a catalyst layer 5 formed on the surface thereof. Similarly, the hydrogen electrode 2 is composed of an electrode substrate 6 made of a carbon sheet and a catalyst layer 7 formed on the surface thereof. Have been. Examples of the type of the catalyst include platinum, platinum alloy, palladium, magnesium, titanium, manganese, lanthanum, vanadium, zirconium, nickel-lanthanum alloy, titanium-iron alloy, iridium, rhodium, gold, and the like.
Platinum and platinum alloy.

Further, as shown in FIG.
A positive electrode lead 8 is led out of the electrode substrate 4 of the first embodiment, and a negative electrode lead 9 is led out of the electrode substrate 6 of the hydrogen electrode 2.
These positive electrode lead 8 and negative electrode lead 9 are connected to a load (not shown). On the oxygen electrode 1 side, the air 10 is configured to be supplied from the inlet 11 to the flow channel 12 and discharged from the outlet 13, and on the hydrogen electrode 2 side, supplied from the hydrogen supply source 14. The hydrogen 15 is configured to be supplied to the flow path 17 from the inlet 16 and discharged from the outlet 18.

The hydrogen 15 supplied from the inlet 16 to the flow path 17 reaches the catalyst layer 7 formed on the surface of the hydrogen layer 15 through the electrode substrate 6 made of a carbon sheet, and is dissociated into protons and electrons by the catalytic action. You. Among them, the electrons move to the negative electrode lead 9 via the electrode substrate 6 and are supplied to a load (not shown), and the protons move to the oxygen electrode 1 side via the proton conductor 3. On the other hand, the oxygen 10 supplied to the flow channel 12 from the inlet 11 reaches the catalyst layer 5 formed on the surface through the electrode substrate 4 made of a carbon sheet, and is supplied from the proton conductor portion 3 by the catalytic action. The protons and the electrons supplied from the load via the positive electrode lead 8 combine to form water. In this way, a desired electromotive force is extracted.

FIG. 2A shows an oxygen electrode 1 and a hydrogen electrode 2.
FIG. 2B is a schematic perspective view of the oxygen electrode 1 or the hydrogen electrode 2 when viewed from the surface to which oxygen 10 or hydrogen 15 is supplied.
FIG. 3 is a schematic perspective view of the catalyst layer 5 as viewed from a surface on which catalyst layers 5 and 7 are formed.

As shown in FIGS. 2A and 2B,
Oxygen 10 or hydrogen 15 is applied to the oxygen electrode 1 and the hydrogen electrode 2.
A plurality of through holes 19 are formed from the surface on which the catalyst layers 5 and 7 are formed to the surface on which the catalyst layers 5 and 7 are formed. These through holes 19 are ventilation holes for improving the gas permeability of the oxygen electrode 1 and the hydrogen electrode 2, and the oxygen 10 or hydrogen 15 flowing through the flow paths 12 and 17 can be efficiently formed by the through holes 19. 5 and 7 are reached.

The electrode substrate 4 made of a carbon sheet,
In order to sufficiently increase the gas permeability of the oxygen electrode 1 and the hydrogen electrode 2 constituted by the catalyst layer 6 and the catalyst layers 5 and 7, 1c
It is preferable that 400 or more through holes 19 are formed per m ^{2, and} it is particularly preferable that 2500 or more through holes 19 are formed per 1 cm ² . However, if the diameter of the through hole 19 is too large, the mechanical strength of the oxygen electrode 1 and the hydrogen electrode 2 may be reduced, or the amount of the catalyst contained in the catalyst layers 5 and 7 may be insufficient. The diameter on the catalyst layers 5 and 7 side is preferably 0.1 mm or less.

Here, the proton conductor 3 is made of hydrogen 15
Is a membrane that prevents permeation and allows the passage of protons, and the material is not particularly limited, and a carbonaceous material containing carbon as a main component is used as a base material, and a material into which a proton dissociable group is introduced is used. Is preferred. The “proton dissociable group” means a “functional group from which a proton can be eliminated by ionization”.

As the carbonaceous material serving as the base material of the proton conductor portion 3, any material can be used as long as it contains carbon as a main component, but a proton-dissociable group is introduced. Later it is necessary that the ionic conductivity be greater than the electronic conductivity. Here, specific examples of the carbonaceous material serving as a base include a carbon cluster which is an aggregate of carbon atoms and a carbonaceous material including a carbon tube.

There are various types of carbon clusters, and preferred are fullerenes, those having an open end in at least a part of the fullerene structure, those having a diamond structure, and the like. Of course, the invention is not limited thereto, and any material may be used as long as the ion conductivity after introduction of the proton dissociating group is higher than the electron conductivity.

It is most preferable to select fullerene as the carbonaceous material serving as the base material of the proton conductor portion 3, and to include a proton dissociating group such as —OH group or —O
SO ₃ H group, —COOH group, —SO ₃ H group, —OPO
It is preferable to use a material into which _two (OH) groups are introduced as a material of the proton conductor portion 3.

The material of the proton conductor 3 may be a material other than the above-mentioned carbonaceous material containing carbon as a main component, such as a perfluorosulfonic acid resin.

The hydrogen supply source 14 may be a hydrogen cylinder, a hydrogen storage alloy, or a carbonaceous hydrogen storage material. Examples of the carbonaceous hydrogen storage material include fullerene, carbon nanofiber, carbon nanotube, and carbon nanotube.
Examples include carbon soot, nanocapsules, bucky onions, and carbon fibers.

Next, a method of manufacturing the fuel cell according to this embodiment will be described.

First, a carbon sheet to be the electrode bases 4 and 6 for the oxygen electrode 1 and the hydrogen electrode 2 is prepared, and the catalyst layers 5 and 7 are formed on one surface of the carbon sheet. The method for forming the catalyst layers 5 and 7 on one surface of the carbon sheet is not particularly limited, but a method of applying a liquid containing catalyst-supporting carbon to the surface of the carbon sheet by a spray drying method or a dropping method, a method of vapor phase formation, A membrane method and a chemical wet method (liquid layer chemical loading method) can be used.

The method of applying the liquid containing the catalyst-carrying carbon to the surface of the carbon sheet by the spray drying method or the dropping method comprises spraying or dropping the liquid containing the catalyst-carrying carbon and the fibrous carbon on the surface of the carbon sheet. This is a method in which the catalyst-carrying carbon and the carbon sheet are entangled with the fibrous carbon sprayed at the same time by coating, thereby bringing the catalyst-carrying carbon into close contact with the carbon sheet. here,
The catalyst-supporting carbon refers to graphite particles carrying a catalytic substance such as platinum, and the fibrous carbon refers to carbon nanotubes (CNT), carbon nanofibers (CNF), acicular graphite, and the like. Or 2
More than one type can be selected and used.

The carbon nanotube is a tubular carbonaceous material having a diameter of about several nanometers or less, typically about 1.2 to 1.7 nanometers, and is a single-walled carbon nanotube consisting of a single-layer tube. (S
WCNT) and multi-wall carbon nanotubes (MWCNT) in which two or more layers are concentrically overlapped are known. The length is not particularly limited, but is typically about several micrometers. Further, the carbon nanofiber refers to a carbon nanotube having a particularly large diameter among carbon nanotubes. Typically, the diameter is several nanometers or more.
Reach micrometer. In the following description, “carbon nanotube” includes carbon nanofibers. In addition, acicular graphite typically refers to acicular graphite having a diameter of about 200 nanometers and a length of about several micrometers.

When carbon nanotubes are selected as the fibrous carbon, since they are very fine fibrous substances, they have a high ability to entangle and adhere the catalyst-supporting carbon to the carbon sheet. When formed at a high density, the gas permeability of the carbon sheet may be impaired. On the other hand, if acicular graphite is selected as the fibrous carbon, the acicular graphite is a fibrous (acicular) substance that is thicker than carbon nanotubes. Although there is no possibility of impairing the carbonaceous material, the ability to entangle the catalyst-supporting carbon on the carbon sheet and bring it into close contact is not so high. Therefore,
As the fibrous carbon to be introduced into the solution, it is preferable to mix carbon nanotubes and acicular graphite.
If the carbon nanotubes and the acicular graphite are mixed, the catalyst-carrying carbon can be effectively adhered to the carbon sheet while maintaining high gas permeability of the carbon sheet. However, in the present embodiment, the through holes 19 are formed in the oxygen electrode 1 and the hydrogen electrode 2 to improve the gas permeability, so that the gas permeability may be slightly lower at this stage.

The carbon nanotubes can be produced by an arc discharge method using a graphite rod.

The method for forming the catalyst layers 5 and 7 by using a vapor phase film forming method includes a sputtering method and a vacuum evaporation method.
In this method, a catalyst is formed on a carbon sheet using a VD method.

Further, in a method of forming the catalyst layers 5 and 7 using a chemical wet method (liquid layer chemical loading method), for example, an aqueous solution of chloroplatinic acid is treated with sodium hydrogen sulfite or hydrogen peroxide, and then, This is a method of forming a catalyst on a carbon sheet by applying a solution to the carbon sheet.

Next, the same proton conductive material as the material used for the proton conductor portion 3 is applied to the catalyst layers 5 and 7 formed on the carbon sheet. For example, when a material (fullerenol) in which fullerene has a proton-dissociable group -OH group introduced therein is used as the material of the proton conductor 3, fullerenol is used for the catalyst layers 5 and 7 formed on the carbon sheet. Apply.

Thus, the oxygen electrode 1 and the hydrogen electrode 2 constituted by the electrode bases 4 and 6 on which the catalyst layers 5 and 7 are formed are completed.

Next, a plurality of through holes 19 are formed in the oxygen electrode 1 and the hydrogen electrode 2 manufactured by the above steps.

FIGS. 3A to 3C are views showing a process of forming a through hole 19 in the oxygen electrode 1 and the hydrogen electrode 2.
The order of FIGS. 3A to 3C coincides with the time order of the step of forming the through hole 19.

As shown in FIGS. 3A and 3B,
In the step of forming the through holes 19 in the oxygen electrode 1 and the hydrogen electrode 2, a needle 20 is inserted into the oxygen electrode 1 and the hydrogen electrode 2 from the electrode bases 4 and 6 made of a carbon sheet,
The needle 20 is penetrated. As a result, as shown in FIG. 3 (c), the tapered through-hole 1 has a wide opening on the electrode bases 4 and 6 side and a narrow opening on the catalyst layers 5 and 7 side.
9 is formed.

By forming a plurality of such through holes 19 in the oxygen electrode 1 and the hydrogen electrode 2, the oxygen electrode 1 and the hydrogen electrode 2 having the through holes 19 are completed. As described above, the formation density of the through holes 19 is preferably 1 cm ² per 400 or more, particularly preferably equal to 2500 or more per 1 cm ^2. If the diameter of the through hole 19 is too large, the mechanical strength of the oxygen electrode 1 and the hydrogen electrode 2 may be reduced, or the amount of the catalyst contained in the catalyst layers 5 and 7 may be insufficient. The diameter of the catalyst layer 5,
It is preferable that the thickness is 0.1 mm or less on the 7th side.

Next, the oxygen electrode 1 thus completed
The proton conductor 3 is sandwiched between the hydrogen electrode 2 and the oxygen electrode 1, and an inlet 11 for air 10, a flow path 12 and an outlet 13 are provided on the oxygen electrode 1 side, and an inlet for hydrogen 15 is provided on the hydrogen electrode 2 side. 1
6, the fuel cell according to the present embodiment is completed by providing the flow path 17 and the discharge port 18.

According to this embodiment, since a plurality of through holes 19 are formed in the oxygen electrode 1 and the hydrogen electrode 2,
The gas permeability of the oxygen electrode 1 and the hydrogen electrode 2 is high, so that the oxygen 10 or the hydrogen 15 flowing through the channels 12 and 17 reach the catalyst layers 5 and 7 efficiently. For this reason, the fuel cell according to the present embodiment can increase the energy generation efficiency as compared with the related art. Specifically, in the conventional fuel cell using the oxygen electrode and the hydrogen electrode through-hole 19 is not provided, that the energy generation efficiency was 30-35 milliwatts / cm ² approximately, 1 cm ² per 400
In the fuel cell according to the present embodiment using the oxygen electrode 1 and the hydrogen electrode 2 provided with from 2500 to 2500 through holes 19,
Its energy generation efficiency is 50-55 milliwatts / cm
Increased to about ² .

In this embodiment, since the through holes 19 are widely opened on the electrode bases 4 and 6 side, the flow path 1
It is possible to effectively guide the oxygen 10 or the hydrogen 15 flowing through the catalyst layers 2 and 17 to the catalyst layers 5 and 7, and
Since the opening is narrow on the side 7, it is possible to prevent a decrease in the amount of catalyst contained in the catalyst layers 5 and 7.

Next, another preferred embodiment of the present invention will be described.

FIG. 4 is a view showing a schematic configuration of an air battery according to another preferred embodiment of the present invention.

As shown in FIG. 4, an air battery (air-zinc battery) manufactured according to this embodiment is
, A negative electrode 22, and an electrolyte 23 sandwiched between the air electrode 21 and the negative electrode 22. The air electrode 21 is composed of an electrode substrate made of a carbon sheet and a catalyst layer formed on the surface thereof, and has a diameter on the catalyst layer side of about 0.1 mm.
1 mm through holes (not shown) have approximately 40 holes per cm ²
0 are formed. The negative electrode 22 is formed of a zinc plate having a thickness of 100 micrometers. A cathode lead 24 extends from the electrode base of the air electrode 21 and a anode lead 25 extends from the anode 22. The cathode lead 24 and the anode lead 25 are connected to a load (not shown). The air electrode 21, the negative electrode 22, and the electrolyte 23 sandwiched therebetween are sandwiched between Teflon (registered trademark) plates 26a and 26b having a thickness of 3 mm.
a and 27b. Further, a plurality of air holes 28 for supplying air to the air electrode 21 are formed in the Teflon plate 26b. The diameter of the air hole 28 is 1.5 mm.

The air battery having such a configuration can be manufactured by the following method.

First, by the method according to each of the above embodiments,
The air electrode 21 is produced by forming a catalyst layer on the surface of the carbon sheet. Next, a plurality of through holes (not shown) are formed in the air electrode 21 by the method according to the above embodiment. The diameter of the through holes is about 0.1 mm as described above, and the formation density is about 400 per 1 cm ² . next,
A gel of an aqueous solution of zinc chloride as the electrolyte 23 is applied to the catalyst layer of the air electrode 21 to a thickness of about 50 micrometers, and the negative electrode 22 is joined. And
Both surfaces of this joined body are firmly sandwiched between Teflon plates 26a and 26b and fixed with bolts 27a and 27b. Thereby, the air battery is completed.

In the thus manufactured air battery, the reaction represented by the formula (1) proceeds at the air electrode 21,
In the negative electrode 22, the reaction represented by the formula (2) proceeds.

O ₂ + 2H ₂ O + 4e ⁻ → 4OH ⁻・ ・ ・ Equation (1) Zn + 2OH ⁻ → Zn (OH) ₂ + 2e ⁻・ ・ ・ Equation (2) Accordingly, the reaction represented by the equation (3) is performed as a whole. As a result, a predetermined electromotive force can be obtained.

_1/2 O ₂ + Zn + H ₂ O → Zn (OH) ₂ ... Equation (3) FIG. 5 is a graph showing the discharge characteristics of an air battery according to another preferred embodiment of the present invention.

FIG. 5 shows the change in output voltage (load characteristic) when the current density is changed, in the air battery according to the present embodiment in which the air electrode 21 has a plurality of through holes, and in the air electrode 21. Each of the conventional air batteries without a through-hole is shown.

Referring to FIG. 5, the open-circuit voltage (when the current value is zero) is almost the same, but as the current density increases, the air battery according to the present embodiment is different from the conventional air battery. It can be seen that the output voltage is maintained higher. From this result, it is understood that the air battery according to the present embodiment in which the air electrode 21 has a plurality of through holes has higher output characteristics than the conventional air battery.

The present invention is not limited to the above embodiments, and various modifications can be made within the scope of the invention described in the claims, and these are also included in the scope of the present invention. It goes without saying that it is a thing.

For example, in the above embodiment, the through holes 19 are formed in both the oxygen electrode 1 and the hydrogen electrode 2, but it is not always necessary to form the through holes 19 in both the oxygen electrode 1 and the hydrogen electrode 2. Alternatively, the through hole 19 may be formed in only one of the oxygen electrode 1 and the hydrogen electrode 2. In this case, on the hydrogen electrode 2 side, it is general that hydrogen 15 pressurized than the atmospheric pressure is supplied from an inlet 16 to force the hydrogen 15 to flow through, while the hydrogen electrode 2 side is forced to flow. Since it is common that oxygen 10 is not particularly pressurized, particularly high gas permeability is required on the oxygen electrode 1 side. Therefore, it is desired to form the through hole 19 at least on the oxygen electrode 1 side. Further, as described above, since there is a difference in required gas permeability between the oxygen electrode 1 and the hydrogen electrode 2, even when the through holes 19 are formed in both the oxygen electrode 1 and the hydrogen electrode 2, In the oxygen electrode 1 and the hydrogen electrode 2, the formation density and the diameter of the through holes 19 may be different. In this case, considering that higher gas permeability is required on the oxygen electrode 1 side, the formation density of the through holes 19 is made higher on the oxygen electrode 1 side than on the hydrogen electrode 2 side, and the diameter of the through holes 19 is increased. Oxygen electrode 1
It is preferable that the side is set larger than the hydrogen electrode 2 side.

In the above embodiment, the catalyst layers 5, 7 are provided on one surface of the carbon sheet as the electrode bases 4, 6.
When a spray-drying method or a dropping method is used as a method for forming a liquid, a liquid containing catalyst-supporting carbon and fibrous carbon is applied by spraying or dropping onto the surface of a carbon sheet. Alternatively, the liquid containing this may be spray-coated or dropped-coated on the surface of the carbon sheet. As a method for supporting a catalyst on carbon nanotubes, a chemical supporting method using a solution containing a platinum complex (liquid layer chemical supporting method)
Alternatively, an arc discharge method using a carbon-based electrode containing platinum may be applied.

Further, in the above embodiment, after the catalyst layers 5 and 7 are formed on the surface of the carbon sheet, the same proton conductive material is applied to the catalyst layers 5 and 7. When a spray drying method or a dropping method is used as a method for forming the catalyst layer, the formation of the catalyst layers 5 and 7 and the application of the proton conductive material may be performed simultaneously by mixing a proton conductive material into the liquid. However, in the present invention, it is not essential to apply the proton conductive material to the catalyst layers 5 and 7, and this may be omitted.

In the above embodiment, the through hole 1
In the formation of 9, a needle 20 is pierced from the electrode bases 4 and 6 side to form a tapered through hole 19 that is wide open on the electrode bases 4 and 6 side and narrowly open on the catalyst layers 5 and 7 side. However, in the present invention, it is not essential that the through-hole 19 be tapered, and the opening diameter may be the same on the electrode bases 4 and 6 side and the catalyst layers 5 and 7 side.

Further, in the above embodiment, hydrogen gas is used as the fuel gas of the fuel cell manufactured. However, the fuel gas is not limited to hydrogen gas, and other fuel gas, for example, methanol is vaporized. You may use the gas made to have. In this case, the reaction represented by the formula (4) proceeds in the negative electrode to which the gas obtained by vaporizing methanol is supplied, and the reaction represented by the formula (5) in the oxygen electrode 1 (the positive electrode) to which air is supplied. Progresses.

[0098] _{CH 3 OH + H 2 O →} CO 2 + 6H + + 6e - ··· Equation _{^{(4) 6H + + 3 /}} 2O 2 + 6e - → 3H 2 O ··· (5) Thus, as a whole the formula (6) The reaction shown in (1) proceeds, and a predetermined electromotive force can be obtained.

CH ₃ OH + 3 / 2O ₂ → CO ₂ + 2H ₂ O Formula (6) However, when a gas obtained by vaporizing methanol is used as the fuel gas, carbon dioxide is generated in addition to water.

[0100]

As described above, according to the present invention,
Since a plurality of through holes 19 are formed in the oxygen electrode 1 and the hydrogen electrode 2, the gas permeability of the oxygen electrode 1 and the hydrogen electrode 2 is high, and therefore, the energy generation efficiency of the fuel cell can be greatly improved. It becomes possible.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration of a fuel cell to be manufactured according to a preferred embodiment of the present invention.

FIG. 2A shows an oxygen electrode 1 and a hydrogen electrode 2,
FIG. 2B is a schematic perspective view of the oxygen electrode 1 and the hydrogen electrode 2 when viewed from the surface to which oxygen 10 or hydrogen 15 is supplied.
FIG. 4 is a schematic perspective view as seen from a surface on which catalyst layers 5 and 7 are formed.

3 (a) to 3 (c) are views showing a process of forming a through hole 19 in the oxygen electrode 1 and the hydrogen electrode 2. FIG.

FIG. 4 is a view showing a schematic configuration of an air battery according to another preferred embodiment of the present invention.

FIG. 5 is a graph showing a discharge characteristic of an air battery according to another preferred embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Oxygen electrode 2 Hydrogen electrode 3 Proton conductor part 4, 6 Electrode substrate 5, 7 Catalyst layer 8 Positive electrode lead 9 Negative electrode lead 10 Air 11 Inlet 12 Channel 13 Outlet 14 Hydrogen supply source 15 Hydrogen 16 Inlet 17 Channel Reference Signs List 18 outlet 19 through hole 20 needle 21 air electrode 22 negative electrode 23 electrolyte 24 positive electrode lead 25 negative electrode lead 26a, 26b Teflon plate 27a, 27b bolt 28 air hole

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01M 8/10 H01M 8/10

Claims (43)

[Claims] 1. A gas diffusion electrode comprising a carbon sheet having a catalyst layer formed on one surface, and a plurality of through holes formed from the one surface to the other surface. 2. The gas diffusion electrode according to claim 1, wherein 400 or more through holes are formed per 1 cm ² . 3. The method according to claim 1, wherein the through hole has a thickness of 2500 per cm ^2.
The gas diffusion electrode according to claim 2, wherein at least one gas diffusion electrode is formed. 4. The gas diffusion electrode according to claim 1, wherein the diameter of the through hole is 0.1 mm or less on the one surface. 5. The gas diffusion electrode according to claim 1, wherein an opening diameter of the through hole in the one surface is smaller than an opening diameter in the other surface. 6. The gas diffusion electrode according to claim 1, wherein a proton conductive material is applied to the catalyst layer. 7. A catalyst layer forming step of forming a catalyst layer on one surface of the carbon sheet, and a through hole forming step of forming a plurality of through holes from the one surface to the other surface of the carbon sheet. A method for producing a gas diffusion electrode comprising: 8. The method for manufacturing a gas diffusion electrode according to claim 7, wherein the through hole forming step includes forming at least 400 through holes per cm ^{2 in the} carbon sheet. 9. The method for producing a gas diffusion electrode according to claim 8, wherein the through hole forming step forms at least 2500 through holes per cm ^{2 in the} carbon sheet. 10. The gas diffusion according to claim 7, wherein the through hole forming step forms a through hole having a diameter of 0.1 mm or less on the one surface of the carbon sheet. Manufacturing method of electrode. 11. The method for manufacturing a gas diffusion electrode according to claim 7, wherein the through hole forming step is performed by piercing a needle from the other surface of the carbon sheet to the one surface. . 12. The method according to claim 7, wherein the catalyst layer forming step is performed by applying a liquid containing a catalyst-supporting carbon to the one surface of the carbon sheet.
3. The method for producing a gas diffusion electrode according to item 1. 13. The method according to claim 12, wherein the liquid contains fibrous carbon. 14. The method according to claim 7, wherein the catalyst layer forming step is performed by a vapor deposition method. 15. The method according to claim 7, wherein the catalyst layer forming step is performed by a chemical wet method. 16. The method according to claim 7, further comprising an application step of applying a proton conductive material to the catalyst layer formed on the one surface of the carbon sheet. 17. The method according to claim 16, wherein the applying step is performed before the through-hole forming step. 18. A gas diffusion electrode having a catalyst layer formed on one surface and an electrolyte membrane attached to the one surface of the gas diffusion electrode, wherein the gas diffusion electrode includes An electrochemical device, wherein a plurality of through holes are formed from one surface to the other surface. 19. The electrochemical device according to claim 18, wherein the electrochemical device is a fuel cell. 20. The electrochemical device according to claim 18, wherein the electrochemical device is an air battery. 21. The method according to claim 19, wherein the through-hole is 400 / cm ^2.
19. The electrochemical device according to claim 18, wherein at least one is formed. 22. The method according to claim 19, wherein the through hole has a thickness of 250 per cm ^2.
20. The electrochemical device according to claim 19, wherein zero or more are formed. 23. The device according to claim 1, wherein the diameter of the through hole is 0.1 mm or less on the one surface.
9. The electrochemical device according to 8. 24. The electrochemical device according to claim 18, wherein an opening diameter of the through hole on the one surface is smaller than an opening diameter on the other surface. 25. The electrochemical device according to claim 19, wherein a proton conductive material is applied to the catalyst layer. 26. An oxygen electrode having a catalyst layer formed on one surface, a fuel electrode having a catalyst layer formed on one surface, the one surface of the oxygen electrode and the one surface of the fuel electrode. Wherein the oxygen electrode and the fuel electrode are each provided with a plurality of through holes formed from the one surface to the other surface. And the fuel cell. 27. The fuel cell according to claim 26, wherein the formation density of the through holes in the oxygen electrode is different from the formation density of the through holes in the fuel electrode. 28. The fuel cell according to claim 27, wherein the formation density of the through holes in the oxygen electrode is higher than the formation density of the through holes in the fuel electrode. 29. The fuel cell according to claim 26, wherein a diameter of the through hole in the oxygen electrode is different from a diameter of the through hole in the fuel electrode. 30. The fuel cell according to claim 29, wherein a diameter of the through hole in the oxygen electrode is larger than a diameter of the through hole in the fuel electrode. 31. A process for forming a catalyst layer on one surface of a carbon sheet and a process for forming a plurality of through-holes from the one surface to the other surface of the carbon sheet. A method for manufacturing an electrochemical device, comprising: forming a diffusion electrode; and attaching an electrolyte membrane to the catalyst layer of the gas diffusion electrode. 32. The method according to claim 31, wherein the electrochemical device is a fuel cell. 33. The method according to claim 31, wherein the electrochemical device is an air battery. 34. The method for producing an electrochemical device according to claim 31, wherein the through-hole forming step forms at least 400 through-holes per cm ^{2 in the} carbon sheet. 35. The method for producing an electrochemical device according to claim 34, wherein the through hole forming step forms at least 2500 through holes per cm ^{2 in the} carbon sheet. 36. The electrochemical device according to claim 31, wherein the through hole forming step forms a through hole having a diameter of 0.1 mm or less on the one surface of the carbon sheet. Device manufacturing method. 37. The method according to claim 31, wherein the through-hole forming step is performed by piercing a needle from the other surface of the carbon sheet to the one surface. . 38. The method according to claim 3, wherein the catalyst layer forming step is performed by applying a liquid containing a catalyst-supporting carbon to the one surface of the carbon sheet.
2. The method for producing an electrochemical device according to item 1. 39. The method according to claim 38, wherein the liquid contains fibrous carbon. 40. The method according to claim 31, wherein the catalyst layer forming step is performed by a vapor phase film forming method. 41. The method according to claim 31, wherein the catalyst layer forming step is performed by a chemical wet method. 42. The method for manufacturing an electrochemical device according to claim 32, further comprising a coating step of coating a proton conductive material on the catalyst layer formed on the one surface of the carbon sheet. 43. The method according to claim 42, wherein the applying step is performed before the through-hole forming step.