JP2000208152A - Electrode for fuel cell and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify manufacture of an electrode in a fuel cell. SOLUTION: This electrode 10 comprises a catalyst layer 12 and a gas diffusion layer 14. The catalyst layer 12 includes a catalyst carrying layer 16 and a buffer layer 18. The buffer layer 18 prevents direct contact between the catalyst carrying layer 16 and an electrolyte layer 20 to prevent inflow of an electrolyte into the catalyst carrying layer 16. The electrode 10 wherein the plural layers 12 (16, 18), 14 are laminated is formed by weaving continuous reinforcing fiber. The continuous reinforcing fiber is composed of fiber bundles having electric conductivity. Regions constituting the catalyst carrying layer 16, the buffer layer 18, the electrolyte layer 20 and the gas diffusion layer 14 are respectively formed by impregnating components of a required catalyst, electrolyte and the like into the fiber bundle. By weaving the continuous reinforcing fiber formed with the respective regions, the electrode 10 wherein the catalyst layer 12 and the gas diffusion layer 14 are laminated is manufactured.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel cell electrode and a method for manufacturing the same, and more particularly, to an electrode containing a fiber material.

[0002]

2. Description of the Related Art A fuel cell is a cell that directly converts reaction energy of a raw material gas into electric energy.
Power generation is performed in units of a single cell as shown in FIG. The single cell 1 is configured such that a joined body 2 is sandwiched between separators 4, and the joined body 2 is provided on both sides of an electrolyte layer 5 with a catalyst layer 6 and a gas diffusion layer 7 coated on the catalyst layer 6. And an electrode comprising: One of these electrodes is on the anode side, and the other is on the cathode side. Here, the electrolyte layer 5 functions as an ion conductor of the fuel cell, and the type of the fuel cell is classified according to the type of the electrolyte layer. These include a solid polymer type, a solid oxide type, and a molten oxide type. There are carbonic acid type and phosphoric acid type.

For example, in a polymer electrolyte fuel cell using a polymer electrolyte membrane as an electrolyte, hydrogen as a fuel gas and oxygen as an oxidizing gas are supplied to a gas flow path 8 provided on a sandwiching surface of a separator 4. I do. These are supplied to the catalyst layer 6 via the gas diffusion layer 7. Among them, the hydrogen gas generates protons in the catalyst layer 6 on the anode side, and emits electrons to an external circuit. The generated protons move to the oxygen side through the electrolyte 5 and react with oxygen in the oxygen-side catalyst layer 6 (cathode-side catalyst layer) to generate water.

[0004] The gas diffusion layer 7 disposed between the catalyst layer 6 and the gas flow channel 8 satisfactorily diffuses the gas flowing through the gas flow channel 8 into the catalyst layer 6, as well as the separator 4 and the catalyst layer 6.
, And the wear of the catalyst layer 6 due to the contact of the separator 4 with the catalyst layer 6 is prevented. As a base material of such a gas diffusion layer, for example, as described in Japanese Patent Application Laid-Open No. 60-21774, carbon paper, carbon cloth, or the like is mainly used.

However, when carbon cloth, carbon paper, or the like is used as the electrode, there is a problem that the gas diffusivity is reduced. In order to solve such a problem of the gas diffusion layer, a gas diffusion layer capable of improving gas diffusivity has been developed.
No. 7897.

This electrode comprises a catalyst layer comprising carbon particles carrying a catalyst, carbon particles and a water-repellent resin,
The gas diffusion layer is configured such that short carbon fibers adhere to the surface opposite to the catalyst layer in a state of being entangled with the carbon particles. As described above, since the diffusion layer covers the surface of the layer by entanglement of the conductive carbon short fibers, the strength of the layer is secured without using an electrode base material such as carbon cloth or carbon paper, and the catalyst layer is formed. And at the same time, the electrodes can be made thinner while ensuring conductivity with the current collector, so that gas diffusivity and excess water drainage are improved.

[0007]

However, the conventional electrode in which carbon fibers are adhered to the gas diffusion layer has a problem that the manufacturing process is complicated. That is, the conventional method for manufacturing an electrode includes a method of first manufacturing a gas diffusion layer, then manufacturing a catalyst layer, and finally integrating the gas diffusion layer and the catalyst layer by hot pressing or the like. Process was included.

Further, in the conventional electrode, the catalyst layer and the gas diffusion layer are integrated by applying heat and pressure by using a hot press, so that carbon particles and the like in the catalyst layer and the gas diffusion layer are aggregated and uniform. There is also a problem of affecting the electrical conductivity and the like.

Accordingly, the present invention has been made in view of the above problems, and an object of the present invention is to simplify the production of an electrode in a fuel cell.

[0010]

In order to achieve the above object, the present invention provides a method for producing a fuel cell electrode having a gas diffusion layer and a catalyst layer by weaving continuous reinforcing fibers. The continuous reinforcing fiber impregnates a gas diffusion layer component in a region constituting the gas diffusion layer on a fiber bundle having one electric conductivity, and impregnates a catalyst layer component in a region constituting the catalyst layer. It is characterized by being generated by performing

According to the above invention, the gas diffusion layer region and the catalyst layer region are formed on the continuous reinforcing fiber, and the electrodes are formed by weaving the gas diffusion layer region and the catalyst layer. . Therefore, since it is not necessary to press the gas diffusion layer and the catalyst layer separately manufactured using a hot press or the like as in the related art, it is possible to simplify the manufacturing and provide an electrode of stable quality. .

Further, the present invention is an electrode for a fuel cell in which at least a gas diffusion layer and a catalyst layer are formed in a laminated manner, wherein at least a gas diffusion layer region and a catalyst layer component are impregnated on an electrically conductive fiber bundle. The gas diffusion layer and the catalyst layer are laminated and formed by weaving a continuous reinforcing fiber having a catalyst layer region.

According to the above invention, since the gas diffusion layer and the catalyst layer are integrally formed from continuous fibers having electrical conductivity, an electrode having excellent electrical conductivity between the catalyst layer and the separator is formed. Can be configured. Further, since the gas diffusion layer is made of fibers, the gas diffusion layer is also excellent in gas diffusion properties.

Further, according to the present invention, in the electrode of the above invention, the catalyst layer has a buffer layer formed on a surface opposite to a surface adjacent to the gas diffusion layer. A buffer layer region impregnated with a buffer component is formed.

According to the present invention, since the catalyst layer is provided with the buffer layer on the surface facing the electrolyte, it is possible to prevent the catalyst layer from flowing out of the catalyst layer and the electrolyte from flowing into the catalyst layer. It is possible to use the electrode, especially the catalyst layer, for a long time without deforming the catalyst layer.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a fuel cell electrode according to the present embodiment, and FIG. 2 shows an electrode manufacturing apparatus according to the present embodiment.

As shown in FIG. 1, the electrode 10 of the present embodiment
Is composed of a catalyst layer 12 and a gas diffusion layer 14. The catalyst layer 12 further includes a catalyst support layer 16 and a buffer layer 18. The catalyst supporting layer 16 is a layer that supports a catalyst, ionizes an oxidizing gas such as a fuel gas such as a hydrogen gas or oxygen supplied, and simultaneously generates electrons. Further, the buffer layer 18 prevents direct contact between the catalyst supporting layer 16 and the electrolyte layer 20 to prevent the electrolyte from flowing into the catalyst supporting layer 16, or prevents the catalyst from flowing into the electrolyte layer 2.
It is prevented from flowing out to zero. Gas diffusion layer 1
4 is a catalyst supporting layer 16 for supplying the supplied fuel gas or oxidizing gas.
To spread.

As described above, the structure of the gas diffusion layer 14 and the catalyst layer 12 is the same as that of the conventional electrode.
In this electrode, the catalyst layer 12 and the gas diffusion layer 14 are composed of continuous reinforcing fibers. That is, the continuous reinforcing fiber is formed on the fiber bundle having electric conductivity by the catalyst layer 1.
2 and a region forming the gas diffusion layer 14 are formed to form a continuous reinforcing fiber. By laminating the reinforcing fibers, a laminated structure of the catalyst layer 12 and the gas diffusion layer 14 is formed.

Hereinafter, a method for manufacturing the electrode 10 of the present embodiment will be described in detail using a continuous reinforcing fiber manufacturing apparatus 22 shown in FIG.

As shown in FIG. 2, first, in order to generate reinforcing fibers by the device 22, a fiber bundle to be used as a base is selected.
prepare. The fiber bundle 24 needs to be electrically conductive so that electrons can be transferred between the electrodes 10 on the anode side and the cathode side. As the fiber bundle 24 having electrical conductivity, there are metal fibers such as ceramic fibers, carbon fibers, silicon fibers, boron fibers, and aluminum fibers, and an appropriate fiber can be used. . The diameter of the fiber bundle 24 is not particularly limited, and may be a needle-like thin diameter like a whisker or a thick diameter like a general metal fiber. Generally, ceramic diameter,
The diameter of the fiber bundle becomes large, such as the diameter of the carbon ceramic and the metal.

When such a fiber bundle 24 is prepared, the fiber bundle 24 is wound around a reel 26 and installed in the apparatus 22.
One end of the fiber bundle 24 wound around the reel 26 is inserted into the opening unit 28. The fiber opening section 28 includes an impregnating section 3 described later.
At 0, the fiber bundle 24 is loosened and opened to facilitate impregnation of the fiber bundle 24 with a catalyst or the like. As a result, the fiber bundle 24 sent out from the opening unit 28 is in a state 24a in which the diameter is expanded.

The fibers 24 sent out from the opening unit 28 are
Next, it is sent into the impregnation part 30. The impregnating section 30 impregnates the components constituting the gas diffusion layer 14, the catalyst supporting layer 16, and the buffer layer 18 with necessary components. For example, in a region constituting the catalyst supporting layer 16 (hereinafter, referred to as a catalyst supporting region 36), it is necessary to impregnate the portion of the fiber bundle 24 with a catalyst.

The catalyst supporting region 36 and the buffer layer 1
8 (hereinafter referred to as a buffer area 38),
The region constituting the gas diffusion layer 14 (hereinafter, the gas diffusion region 3
4) is determined according to the final weaving shape in the weaving unit 46 described later, and the control unit 32
Each of these areas is designated, and the impregnating section 30 impregnates each area with necessary components.

Here, as a component to be impregnated in the catalyst supporting region 36, a Nafion solution (Dup) is used as an electrolyte component.
slurry) in which a catalyst is mixed. This Nafion solution is a suspension of Nafion in a solution of propanol, ethanol, water or the like.
It is known that Nafion has a perfluorocarbon in its basic skeleton, is rich in ion exchange properties, and has high proton conductivity. Therefore, by using this Nafion solution, it is possible to improve power generation characteristics.

The catalyst carrying region 36 can be different between the anode side and the cathode side. For example, in the case of the anode side, a platinum (Pt) -ruthenium (Pu) binary catalyst supported on carbon is used as a catalyst, and a slurry in which this catalyst is suspended in a cyclohexanol or Nafion solution is used. be able to. On the other hand, on the cathode side, a platinum (Pt) catalyst supported on carbon was used as a catalyst, and the catalyst was cyclohexanol,
A slurry suspended in a Nafion solution can be used.

As a component to be impregnated into the buffer region 38, the buffer layer 18 is intended to prevent direct contact between the catalyst supporting layer 16 and the electrolyte layer 20, thereby preventing outflow of the catalyst and the like. Any component may be used as long as it can achieve this purpose. For example,
As this component, an electrolyte component such as a Nafion solution to which the above-mentioned catalyst is not added can be used. When a Nafion solution is used, the proton conductivity can be increased as described above, and the power generation characteristics can be improved.

Further, the gas diffusion region 34 is provided with a catalyst supporting layer 16 for the fuel gas and the oxidizing gas supplied to the gas diffusion layer 14.
It is necessary to improve the diffusion to the semiconductor and to have electric conductivity. Therefore, as in the present embodiment, the fiber bundle 2
4 has electric conductivity, and the fiber bundle 24 has a large number of holes through which many gases can pass. Therefore, it is not necessary to impregnate the gas diffusion region 34 with any component. Therefore, here, the gas diffusion region 34 is left unimpregnated without any component impregnation. However, the gas diffusion region is not limited to the non-impregnated region, and may be impregnated with a component or the like that further improves gas diffusion and electrical conductivity.

As described above, in the impregnating section 30, the catalyst carrying area 36 and the buffer area 38 designated by the control section 32 are provided.
Is impregnated with a slurry containing a catalyst and an electrolyte. On the other hand, as described above, the gas diffusion region 34 maintains the state of no impregnation. Therefore, the gas diffusion area 34 and the catalyst supporting area 3
6. The buffer area 38 is formed, sent out, and sent to the press section 40. In the press section 40, the fiber bundle opened by the fiber opening section 28 is pressed and closed, and the reinforcing fibers 42 are formed. The necessary catalysts 42a, electrolytes 42b, and the like are carried in appropriate regions on the reinforcing fibers 42.

The formed reinforcing fibers 42 are sent to a take-up drum 44 and wound up. The reinforced fiber 42 wound here is sent to an automatic loom 46,
Here, the catalyst layer 12 and the gas diffusion layer 14 are formed by weaving. As the shape to be woven by the automatic loom 46, a woven shape that allows gas to pass easily and has good electric conductivity is selected. As this woven shape, those described in a ceramics-based composite material (Agne Shofu Co., Ltd.) can be adopted. More specifically, there are biaxial woven fabrics, various melias types, mat types, various blade types, and the like.

As described above, in the fuel cell electrode of the present embodiment, the gas diffusion region, the catalyst carrying region, and the buffer region are formed in the fiber bundle, and the gas diffusion layer,
A catalyst layer is formed by lamination. Therefore, a step of pressing the catalyst layer and the gas diffusion layer separately formed as in the related art is not required, and the production can be simplified.

The electrodes manufactured by this method are not only simple to manufacture, but also have various advantageous characteristics. That is, the electrode 10 comprises the gas diffusion layer 14 and the catalyst layer 1.
When forming the laminated structure of No. 2, it is possible to provide an electrode of stable quality without causing problems such as poor press bonding and unevenness of components at the time of pressing by hot press to which heat and pressure are applied. . Further, since the gas diffusion layer 14 is formed by weaving reinforcing fibers, the gas diffusion layer 14 is porous and rich in gas diffusion. Further, the gas diffusion layer 14 and the catalyst layer 12
Is composed of continuous reinforcing fibers, the electrical conductivity between them is good, and although not shown, the efficiency of electrical conduction to a current collector such as a separator can be increased.

Further, in the electrode 10 of this embodiment, since the buffer layer 18 is provided between the catalyst supporting layer 16 and the electrolyte layer 20, the catalyst of the catalyst supporting layer 16 is
It can be prevented from flowing out to zero.

In the above description, the electrolyte layer 20 is used, but various electrolyte layers such as a solid polymer electrolyte membrane, a solid oxide electrolyte membrane, and a phosphoric acid electrolyte solution can be used. That is, the electrode of the present embodiment can be applied to a polymer electrolyte fuel cell, a solid oxide fuel cell, a phosphoric acid fuel cell, and a molten carbonic acid fuel cell.

[0034]

As described above, according to the present invention, the production of an electrode for a fuel cell is simplified, and the produced electrode is
Since the layers are not press-bonded by a conventional hot press or the like, problems such as component bias are avoided, and quality is improved because of excellent electrical conductivity.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating an overall configuration of an electrode according to an embodiment.

FIG. 2 is an overall configuration diagram of a manufacturing apparatus for manufacturing an electrode according to the present embodiment.

FIG. 3 is a diagram showing an entire configuration of a conventional electrode.

[Explanation of symbols]

Reference Signs List 10 electrode, 12 catalyst layer, 14 gas diffusion layer, 16
Catalyst support layer, 18 buffer layer, 24 fiber bundles, 34
Gas diffusion area, 36 catalyst carrying area, 38 buffer area, 42 reinforcing fiber.

Claims (3)

[Claims] 1. A method for producing a fuel cell electrode having a gas diffusion layer and a catalyst layer by weaving continuous reinforcing fibers, wherein the continuous reinforcing fibers have a single electrical conductivity. Producing an electrode for a fuel cell, wherein a region constituting the gas diffusion layer is impregnated with a gas diffusion layer component on the bundle, and a region constituting the catalyst layer is impregnated with the catalyst layer component. Method. 2. A fuel cell electrode in which at least a gas diffusion layer and a catalyst layer are formed by lamination, wherein at least a gas diffusion layer region and a catalyst layer region in which a catalyst layer component is impregnated on an electrically conductive fiber bundle. The electrode for a fuel cell, wherein the gas diffusion layer and the catalyst layer are laminated and formed by weaving a continuous reinforcing fiber formed with. 3. The catalyst layer has a buffer layer formed on a surface opposite to a surface adjacent to a gas diffusion layer, and a buffer layer region impregnated with a buffer component in the continuous reinforcing fibers. The fuel cell electrode according to claim 2, wherein the electrode is formed.