JPH0577151B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an electrode/matrix assembly for a matrix fuel cell using, for example, phosphoric acid as an electrolyte, and a method for manufacturing the same.

[Conventional technology]

FIG. 4 is a process diagram of a conventional method for manufacturing an electrode/matrix assembly for a fuel cell disclosed in, for example, Japanese Unexamined Patent Publication No. 58-165259. In the figure, 1 is a preparatory step for preparing an electrode base material. , 2 is a water repellent treatment step in which the electrode base material obtained in this preparation step 1 is subjected to a water repellent treatment, and 3 is a first catalyst layer as a first layer on the electrode base material treated in this water repellent treatment step 2. coating process,
4 is a firing step of firing the electrode coated with the first catalyst layer in this coating step 3, and 5 is a firing step of firing the electrode coated with the first catalyst layer in coating step 3;
Step 6 is a step of removing a pore-forming agent such as ammonium bicarbonate from the second catalyst layer; Step 7 is firing the electrode coated with the second catalyst layer. A firing step 8 is a matrix layer coating step of applying a matrix material on the second catalyst layer, and 9 is a firing step of firing the electrode/matrix assembly obtained in this coating step 8.

An example of the electrode/matrix assembly obtained through the above manufacturing process is shown in FIG. In the figure, 10 is an electrode base material, 11 is a catalyst layer coated on the surface of this electrode base material 10, and 11a
is the first catalyst layer of this catalyst layer 11, 11
Similarly, b is the second catalyst layer, and 12 is a matrix layer coated on the surface of the catalyst layer 11. 13 is a catalyst powder constituting the catalyst layer 11; 14 is a water repellent agent that also serves as an adhesive, such as polytetrafluoroethylene; 15 is a matrix powder material constituting the matrix layer 12; 16 is also a matrix. It is a binder that constitutes the layer 12.

A conventional fuel cell electrode/matrix assembly and its manufacturing method are constructed as described above. First, in the electrode base material preparation step 1, a porous material (generally carbon paper etc. is used as the electrode base material 10). ) is prepared, and a water repellent treatment step 2 is performed in which a water repellent binder such as polytetrafluoroethylene is coated and dried. Next, in the first catalyst layer 11a coating step 3, a mixture of catalyst powder 13 and water repellent 14 is coated on the water-repellent electrode base material 10 to form the first catalyst layer 11a, and then baked. In step 4, the electrode coated with the first catalyst layer 11a is fired at a temperature of 300° C. for 5 minutes. Next, in the second catalyst layer coating step 5, for example, 100 parts by weight of catalyst powder 13: about 30 to 50 parts by weight of water repellent (e.g. polytetrafluoroethylene) 14 is applied on the first catalyst layer 11a.
Part by weight: Applying the pore-forming agent mixture to the second catalyst layer 1
1b is formed, and in step 6 of removing the pore-forming agent of the second catalyst layer 11b, the pore-forming agent is removed by drying at a temperature of 100° C., and in the firing step 7 after applying the second catalyst layer 11b, the temperature is The electrode is fired at 350° C. to generate pores inside the second catalyst layer 11b. Next, in the coating step 8 of the matrix layer 12,
15,100 parts by weight of matrix powder material (for example, silicon carbide, etc.) on the second catalyst layer 11b:
Binder (polytetrafluoroethylene, etc.) 168
The matrix layer 12 is formed by coating a part of the mixture by weight so as to fill the pores of the second catalyst layer 11b. Bake for 5 minutes to complete the electrode/matrix assembly.

As is well known, this type of fuel cell is constructed by sandwiching a matrix layer impregnated with electrolyte between the fuel electrode and the air electrode, and fuel gas containing hydrogen is supplied to the fuel electrode and air is supplied to the air electrode. It is a device that can directly extract electrical energy from the electrochemical reaction.

[Problem that the invention seeks to solve]

In the electrode/matrix assembly of a fuel cell as described above, when an electrolyte such as phosphoric acid is applied or replenished to the matrix layer 12 during or after battery assembly, the electrolyte such as phosphoric acid is applied to the matrix layer 12. There is a problem that it is difficult to impregnate in the longitudinal direction of the catalyst layer 11b and also difficult to penetrate in the direction of the second catalyst layer 11b, that is, in the direction through the matrix layer 12. The cause of this is that the second catalyst layer 11b
In the baking step 7 after coating, the electrode is heated to a temperature of 350°C.
This is because the highly concentrated water repellent agent 14 in the second catalyst layer 11b gathers near the surface of the second catalyst layer 11b to form a kind of water repellent layer, and the matrix layer This is because the highly concentrated binder 16 in 12 is, for example, polytetrafluoroethylene, which has very strong water repellency.

Further, the electrode/matrix assembly of the fuel cell as described above is manufactured by applying the matrix layer 12 in the coating step 8.
Alternatively, in the firing step 9 after coating the matrix layer 12, problems such as the matrix layer 12 often peeling off from the second catalyst layer 11b or cracks occurring in the matrix layer 12 occur, which impairs the performance of the fuel cell (especially the durability). There was a problem that reduced the bubble quality. The reason for this is the same as above,
In order to bake the electrode at a high temperature of 350°C in the baking step 7 after applying the second catalyst layer 11b, the second
This is because the highly concentrated water repellent agent 14 in the catalyst layer 11b gathers near the surface of the second catalyst layer 11b to form a type of release layer. In addition, in the electrode/matrix assembly of a fuel cell having the above structure and manufactured by the above method, the utilization rate of the catalyst in the electrode is low, and the electrolyte such as phosphoric acid is absorbed once into the catalyst layer 11. There was a problem in that when it permeated, the electrode base material 10 side was easily wetted. This is because the pores in the catalyst layer 11 are partially filled with the matrix layer 12, and the catalyst layer 11 and the matrix layer 12
This is because it is difficult to maintain the balance of wettability such as water repellency and hydrophilicity with respect to the electrolyte such as phosphoric acid in the catalyst layer 11 because it is not a multilayer type.

This invention was made to solve such problems, and includes a multilayer catalyst layer with different mixing ratios of catalyst powder: water repellent: pore-forming agent, and a multilayer catalyst layer with different mixing ratios of matrix powder material: binder. By adopting a combination with a multilayer matrix, it has a matrix layer that has good impregnation and permeability with electrolytes such as phosphoric acid and has good adhesion with the catalyst layer. The objective is to obtain a fuel cell electrode/matrix assembly with improved balance of wettability such as water repellency and hydrophilicity.

In addition to the above object, another object of the present invention is to provide a method for manufacturing the above-described electrode/matrix assembly for a fuel cell.

[Means for solving problems]

The electrode/matrix assembly for a fuel cell according to the present invention includes a porous electrode base material, two or more catalyst layers formed on the surface of the electrode base material each consisting of a catalyst powder and a water repellent, and a catalyst layer formed on the surface of the electrode base material. An electrode/matrix assembly for a fuel cell having two or more matrix layers formed on the surface of each layer, each consisting of a matrix powder material and a binder, wherein the amount of water repellent contained in each catalyst layer is , the porosity of the voids formed by the pore-forming agent in each of the catalyst layers decreases sequentially from the electrode base material side to the matrix layer side. Further, the amount of the binder contained in each of the matrix layers increases sequentially from the catalyst layer side toward the surface side of the matrix layer.

In addition, a method for producing an electrode/matrix assembly for a fuel cell according to another aspect of the present invention includes forming a multilayer catalyst layer on the surface of an electrode base material in which the amounts of both the water repellent agent and the pore forming agent are sequentially decreased. Then, one matrix layer or two or more matrix layers in which the amount of binder is successively increased is formed on the surface of the formed catalyst layer, and the obtained electrode/matrix combination is fired.

[Effect]

In this invention, since the above-mentioned multilayer catalyst layer and matrix layer are formed on the surface of the electrode base material, the balance of wettability such as water repellency and hydrophilicity for electrolytes such as phosphoric acid in the catalyst layer is maintained. A matrix layer with good electrolyte impregnation and permeability and good adhesion with the catalyst layer is formed.

Further, in another aspect of the present invention, the electrode/matrix assembly for a fuel cell as described above can be easily obtained.

〔Example〕

FIG. 1 is a process diagram showing an embodiment of the present invention, and in the figure, 1 and 2 are exactly the same as those in the conventional method. 17 is a coating/drying step in which the first catalyst layer is applied to the electrode base material 10 and dried; 18 is a coating/drying step in which the second catalyst layer is applied on the first catalyst layer and dried; 19 is a second catalyst layer A coating/drying step in which a third catalyst layer is coated on top and dried; 20 is a third catalyst layer;
A coating/drying step in which a first matrix layer is coated on the catalyst layer and dried; 21 is a coating/drying step in which a second matrix layer is coated on the first matrix layer and dried;
A drying step 22 is a pre-baking step 23 of pre-baking the electrode/matrix assembly produced by coating and drying the first, second and third catalyst layers and first and second matrix layers as described above. is a final firing step in which the pre-fired electrode/matrix combination is finally fired.

FIG. 2 is a schematic cross-sectional view of the electrode/matrix assembly of the fuel cell manufactured by the manufacturing process shown in FIG. are the same. 11 is a catalyst layer, and the first catalyst layer 11
A, second catalyst layer 11B, and third catalyst layer 11C
12 is a matrix layer consisting of a first matrix layer 12A and a second matrix layer 12A.
Consists of B.

In the electrode/matrix assembly of the fuel cell configured as described above, first, in electrode base material preparation step 1, a porous material (using phosphoric acid resistant carbon paper, etc.) is prepared as the electrode base material 10. Then, a water repellent treatment step 2 is performed in which a water repellent binder such as polytetrafluoroethylene is applied and dried. Next, in the coating/drying step 17 of the first catalyst layer 11A, catalyst powder 13: water repellent (polytetrafluoroethylene, etc.) 14: pore forming agent (hydrogen carbonate, etc.) ammonium, etc.) 100 parts by weight: 150-400 parts by weight: 20-
Apply the mixture at a mixing ratio of 80 parts by weight, and
The first catalyst layer 11A is formed by drying at 80 to 100°C. Next, the second catalyst layer 11B coating/drying step 1
8, catalyst powder 1 is placed on the first catalyst layer 11A.
3: Water repellent (polytetrafluoroethylene, etc.) 1
4: Apply a mixture of pore-forming agent (ammonium hydrogen carbonate, etc.) at a mixing ratio of 100 parts by weight: 30 to 200 parts by weight: 10 to 50 parts by weight, and dry at a temperature of 80 to 100°C to form the second catalyst. Form layer 11B. Next, in the coating/drying step 19 of the third catalyst layer 11C, catalyst powder 13: water repellent (polytetrafluoroethylene, etc.) 14: pore-forming agent (ammonium hydrogen carbonate, etc.) is applied on the second catalyst layer 11B. A mixture of 100 parts by weight: 1 to 40 parts by weight: 1 to 20 parts by weight is applied and dried at a temperature of 80 to 100°C to form the third catalyst layer 11C.
form. Next, apply the first matrix layer.
In the drying step 20, a matrix powder material (such as silicon carbide with an average particle size of 0.6 to 1 μm) 15: a binder (such as polytetrafluoroethylene with an average particle size of about 1 μm) 1 is placed on the third catalyst layer 11C.
100 parts by weight of 6: 0.1 to 2 parts by weight (preferably 0.5 parts by weight)
~1 part by weight) mixed at a mixing ratio of
Dry at a temperature of 80 to 100℃ to form the first matrix layer 1.
Form 2A. Next, in the second matrix layer coating/drying step 21, a matrix powder material (average particle size
0.6-1 μm silicon carbide, etc.) 15: Binder (polytetrafluoroethylene, etc. with an average particle size of about 1 μm) 16 at a mixing ratio of 100 parts by weight: 1-5 parts by weight (preferably 2-4 parts by weight) The mixture is applied and dried at a temperature of 80 to 100°C to form the second matrix layer 12B. Next, in the pre-firing step 22, the electrodes and
The entire matrix assembly is prefired at a temperature of 150-280°C (preferably 200-250°C). Next, in a final firing step 23, the entire pre-fired electrode/matrix combination is finally fired at a temperature of 310 to 370°C (preferably 330 to 360°C) to complete the electrode/matrix combination.

Fuel cell electrodes manufactured by the above manufacturing method
The matrix combination consists of a second matrix layer 12
The calcination is not performed until the second matrix layer 12B is formed, and the calcination is performed after the second matrix layer 12B is formed. Since the content of the agent 14 and the binder 16 is low, a water-repellent layer is not formed on the bonding surface of the third catalyst layer 11C and the first matrix layer 12A, and the water-repellent layer is not formed on the bonding surface of the third catalyst layer 11C and the first matrix layer 12A. The impregnation and permeability of electrolyte such as phosphoric acid in the direction of , that is, the translayer direction of the matrix layer 12 was improved. Furthermore, a release layer is no longer formed on the surface of the third catalyst layer 11C, and the inconveniences such as peeling of the matrix layer 12 from the third catalyst layer 11C or cracks in the matrix layer 12 are eliminated. . Further, in the catalyst layer 11 of the electrode/matrix combination manufactured by the above manufacturing method, the first catalyst layer 11A has a content of 70 to 90% (preferably about 80%).
%), 55 to 85% (preferably about 70%) in the second catalyst layer 11B, and about 45 to 80% in the third catalyst layer 11C.
(preferably about 60%) voids are formed, and the content of water repellent such as polytetrafluoroethylene in the catalyst layer 11 is higher on the electrode base material 10 side and lower on the matrix layer side 12. The layer 11 has stronger water repellency toward the electrode base material 10;
The hydrophilicity becomes stronger toward the second side, and therefore, it becomes easier to maintain and adjust the balance of wettability between water repellency and hydrophilicity with respect to electrolytes such as phosphoric acid in the catalyst layer. As a result, the disadvantages of conventional electrode/matrix assemblies are improved, and a fuel cell manufactured using the electrode/matrix assembly according to the present invention has a strong matrix layer and an electrolyte such as phosphoric acid. Since the impregnation and permeability were good and the wettability of the catalyst layer 11 was well balanced, the output voltage was high and the change over time was small, making it possible to improve the reliability of the fuel cell.

FIG. 3 is a process diagram showing another embodiment of the present invention, in which numerals 1, 2, 17 to 20 are exactly the same as those in FIG. 1. 24 is a pre-firing step in which the electrode/matrix assembly on which the first, second, and third catalyst layers and the first matrix layer have been coated and dried is pre-baked, and 25 is a pre-baking process in which the pre-baked electrode/matrix assembly is subjected to the main process. 26 is a main firing step of firing, a coating/drying step of applying and drying a second matrix layer on the first matrix layer;
27 is a final firing step in which the electrode/matrix combination is finally fired. A schematic cross-sectional view of the electrode/matrix assembly obtained through these manufacturing steps is the same as that of the above embodiment, and is shown in FIG.

In the electrode/matrix assembly of the fuel cell constructed as described above, the first, second, and third catalyst layers and the first matrix layer are coated and
The dried electrode/matrix assembly is heated to a temperature of 150 to 280°C (preferably
Pre-baking at 200-250℃). Next, in the main firing step 25, the electrode/matrix combination is heated to
Calcinate at 310-370°C (preferably 330-360°C). Next, in a second matrix layer coating/drying step 26, a second matrix layer 12B is coated and dried on the first matrix layer 12A in exactly the same manner as the coating/drying step 21 of FIG. Next, in a final firing step 27, the electrode/matrix assembly coated with the second matrix layer 12B is finally fired at a temperature of 150 to 320°C (preferably 200 to 280°C) to complete the electrode/matrix assembly.

The electrode/matrix assembly manufactured by the above manufacturing method has a catalyst layer 11 and a first matrix layer 1.
Only 2A is fired at high temperature to form the second matrix layer 1.
2B is fired at a low temperature below the melting temperature (327°C) of polytetrafluoroethylene, which is the binder, so the water repellency of the matrix layer 12B is weak.
The impregnation and permeability of electrolytes such as phosphoric acid in the longitudinal direction of the matrix layer 12 were significantly improved, and electrolyte replenishment was also facilitated. Of course, in this case as well, the matrix layer 12 is strong, and the impregnation and permeability of electrolyte such as phosphoric acid in the direction through the matrix layer 12 is good.
Since the wettability of the catalyst layer 11 was well balanced, the output voltage was high and the change over time was small, making it possible to improve the reliability of the fuel cell.

In addition, in the above embodiment, the water repellent 14 of the catalyst layer 11
And polytetrafluoroethylene was used as the binder 16 of the matrix layer 12, but is not limited thereto, and is selected from hexafluoropropylene-tetrafluoroethylene copolymer, graphite fluoride, and polytrifluoroethylene. At least one of the following can also be used. Further, the pore-forming agent for the catalyst layer 11 is not limited to ammonium hydrogen carbonate, and ammonium carboxymethyl cellulose, ammonium carbonate, or the like can also be used.

In the above embodiments, the electrolyte is not limited to phosphoric acid, but can of course also be applied to alkaline solutions. Further, in the electrode/matrix combination, the number of catalyst layers is not limited to three, and the number of matrix layers is not limited to two, and even more catalyst layers and matrix layers can be used.

〔Effect of the invention〕

As explained above, this invention includes a porous electrode base material, two or more catalyst layers formed on the surface of this electrode base material and each consisting of a catalyst powder and a water repellent, and a catalyst layer formed on the surface of this catalyst layer. An electrode/matrix assembly for a fuel cell having two or more matrix layers each consisting of a matrix powder material and a binder, wherein the amount of water repellent contained in each catalyst layer is equal to The porosity of the voids formed by the pore-forming agent in each of the catalyst layers decreases sequentially from the electrode base material side toward the matrix layer side, and Since the amount of binder contained in the matrix layer increases sequentially from the catalyst layer side to the surface side of the matrix layer, it has good impregnation and permeability with electrolytes such as phosphoric acid, and has good adhesion with the catalyst layer. This has the effect of providing an electrode/matrix assembly for a fuel cell that has a good matrix layer and has an improved balance of wettability such as water repellency and hydrophilicity for the electrolyte in the catalyst layer. Furthermore, there is an effect that a highly reliable fuel cell with a high output voltage and a small change over time can be obtained.

Another aspect of the present invention is to form a first catalyst layer by applying and drying a mixed portion of a catalyst powder, a water repellent, and a pore-forming agent on the surface of a porous electrode base material;
A mixture of catalyst powder, a water repellent in a smaller amount than the first catalyst layer, and a pore-forming agent in a smaller amount than the first catalyst layer is coated on the surface of the first catalyst layer and dried to form a second catalyst layer. and applying and drying a mixture of the catalyst powder, a water repellent in a smaller amount than the second catalyst layer, and a pore-forming agent in a smaller amount than the second catalyst layer on the surface of the second catalyst layer. forming a third catalyst layer; and forming a first matrix layer by coating and drying a mixture of a matrix powder material and a binder on the surface of the third catalyst layer formed in the step. , forming a second matrix layer by applying and drying a mixture of a matrix powder material and a binder in a relatively larger amount than the first matrix layer on the surface of the first matrix layer; , and a step of preliminarily firing the electrode/matrix assembly on which the third catalyst layer and the first and second matrix layers are formed, and a final firing of the preliminarily fired electrode/matrix assembly. There is an advantage that the electrode/matrix combination of the fuel cell as described above can be easily obtained.

Still another invention of the present invention includes a step of applying and drying a mixture of a catalyst powder, a water repellent, and a pore-forming agent on the surface of a porous electrode base material to form a first catalyst layer;
A mixture of catalyst powder, a water repellent in a smaller amount than the first catalyst layer, and a pore-forming agent in a smaller amount than the first catalyst layer is coated on the surface of the first catalyst layer and dried to form a second catalyst layer. and applying and drying a mixture of the catalyst powder, a water repellent in a smaller amount than the second catalyst layer, and a pore-forming agent in a smaller amount than the second catalyst layer on the surface of the second catalyst layer. a step of applying a mixture of a matrix powder material and a binder to the surface of the third catalyst layer formed in the above step and drying it to form a first matrix layer; , a step of preliminarily firing the electrode/matrix assembly on which the first, second, and third catalyst layers and the first matrix layer are formed, and a step of main firing the preliminarily fired electrode/matrix assembly; forming a second matrix layer by coating and drying a mixture of a matrix powder material and a binder in a relatively larger amount than the first matrix layer; and a step of final firing the electrode/matrix assembly on which the third catalyst layer and the first and second matrix layers have been formed at a temperature lower than the main firing described above, so that the second matrix layer has weak water repellency and is free from phosphorus. The impregnation and permeability of the acid electrolyte along the matrix layer are significantly improved, the electrolyte can be easily replenished, and a highly reliable fuel cell can be obtained.

[Brief explanation of drawings]

FIG. 1 is a process diagram showing one embodiment of the present invention, FIG. 2 is a schematic sectional view of an electrode/matrix assembly of a fuel cell produced by the process shown in FIG. 1, and FIG. 3 is a process diagram showing an embodiment of the present invention. FIG. 4 is a process diagram showing a conventional method for manufacturing an electrode/matrix assembly for a fuel cell, and FIG. 5 is a process diagram showing an electrode/matrix assembly for a fuel cell manufactured by the process shown in FIG. It is a schematic sectional view. In the figure, 1 is a preparation process, 2 is a water repellent treatment process, 10 is an electrode base material, 11 is a catalyst layer, 11A is a first catalyst layer, 11B is a second catalyst layer, 11C is a third catalyst layer, and 12 is a matrix. layers, 12A is the first matrix layer, 12B is the second matrix layer, 13
is a catalyst powder, 14 is a water repellent, 15 is a matrix powder material, 16 is a binder, 17, 18, 19, 2
0, 21, 26 are coating/drying steps, 22, 24 are preliminary firing steps, 23, 27 are final firing steps, 25
is the main firing process. In each figure, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Scope of Claims] 1. A porous electrode base material; Two or more catalyst layers formed on the surface of this electrode base material and each consisting of a catalyst powder and a water repellent; An electrode/matrix assembly for a fuel cell having two or more matrix layers consisting of a matrix powder material and a binder, wherein the amount of water repellent contained in each catalyst layer is determined from the electrode base material side. The porosity of the voids formed by the pore-forming agent in each of the catalyst layers decreases sequentially from the electrode base material side to the matrix layer side, and An electrode/matrix assembly for a fuel cell, wherein the amount of binder contained in the layer increases sequentially from the catalyst layer side toward the surface side of the matrix layer. 2. The electrode/matrix assembly for a fuel cell according to claim 1, wherein the catalyst layer adjacent to the matrix layer has a porosity such that the voids in the catalyst layer are not filled with the matrix layer. 3. The electrode/matrix assembly for a fuel cell according to claim 1, wherein the same material is used for the water repellent in the catalyst layer and the binder in the matrix layer. 4. The water repellent in the catalyst layer and the binder in the matrix layer are at least one selected from the group consisting of polytetrafluoroethylene, hexafluoropropylene-tetrafluoroethylene copolymer, graphite fluoride, and polytrifluoroethylene. 4. The electrode/matrix assembly for a fuel cell according to claim 3, which is a seed. 5. The pore-forming agent that forms voids in the catalyst layer is at least one selected from the group consisting of ammonium carboxymethyl cellulose, ammonium carbonate, and ammonium hydrogen carbonate. Fuel cell electrodes
Matrix combination. 6 The catalyst layer includes a first catalyst layer, a second catalyst layer, and a third catalyst layer.
There are three catalyst layers, and the matrix layer is the first layer.
The electrode/matrix assembly for a fuel cell according to claim 1, characterized in that it has two layers: a matrix layer and a second matrix layer. 7 The water repellent in the first to third catalyst layers is polytetrafluoroethylene, and the mixing ratio of the water repellent to 100 parts by weight of the catalyst powder in these catalyst layers is as follows:
150 to 400 parts by weight in the first catalyst layer, and 150 to 400 parts by weight in the second catalyst layer.
7. The electrode/matrix assembly for a fuel cell according to claim 6, wherein the amount is 30 to 200 parts by weight, and 1 to 40 parts by weight in the third catalyst layer. 8 The pore-forming agent that forms voids in the first to third catalyst layers is ammonium hydrogen carbonate, and the mixing ratio of the pore-forming agent to 100 parts by weight of the catalyst powder in these catalyst layers is 20% in the first catalyst layer. ~80 parts by weight, 10 to 50 parts by weight in the second catalyst layer, and 1 to 20 parts by weight in the third catalyst layer, the electrode/matrix assembly for a fuel cell according to claim 6 . 9 The porosity of the first to third catalyst layers is 70 to 90% in the first catalyst layer, 55 to 85% in the second catalyst layer, and porosity in the third catalyst layer.
7. The electrode/matrix assembly for a fuel cell according to claim 6, wherein the amount is 45 to 80% in the catalyst layer. 10 The binder in the first and second matrix layers is polytetrafluoroethylene, the average particle size in these matrix layers is approximately 1 μm, and the mixing ratio of the binder to 100 parts by weight of the matrix powder material is In the first matrix layer,
0.1 to 2 parts by weight, 1 to 5 parts by weight in the second matrix layer
7. The electrode/matrix assembly for a fuel cell according to claim 6, wherein the parts are by weight. 11 A step of forming a first catalyst layer by applying and drying a mixture of catalyst powder, a water repellent agent, and a pore-forming agent on the surface of a porous electrode base material; forming a second catalyst layer by coating and drying a mixture of a small amount of water repellent and a relatively small amount of pore-forming agent than the first catalyst layer on the surface of the first catalyst layer; forming a third catalyst layer by applying a mixture of a water repellent in a smaller amount than the catalyst layer and a pore-forming agent in a smaller amount relative to the second catalyst layer on the surface of the second catalyst layer and drying the mixture; , a step of forming a first matrix layer by applying and drying a mixture of a matrix powder material and a binder on the surface of the third catalyst layer formed in the above step; forming a second matrix layer by coating and drying a mixture with a large amount of a binder on the surface of the first matrix layer; Electrode with two matrix layers formed
1. A method for producing an electrode/matrix assembly for a fuel cell, comprising the steps of pre-firing the matrix assembly and final firing of the pre-fired electrode/matrix assembly. 12 Perform preliminary firing at a temperature of 150 to 280°C, and
12. The method for manufacturing an electrode/matrix assembly for a fuel cell according to claim 11, wherein the final firing is performed at a temperature of 310 to 370°C. 13 Forming a first catalyst layer by applying and drying a mixture of catalyst powder, water repellent, and pore-forming agent on the surface of a porous electrode base material; forming a second catalyst layer by coating and drying a mixture of a small amount of water repellent and a relatively small amount of pore-forming agent than the first catalyst layer on the surface of the first catalyst layer; forming a third catalyst layer by applying a mixture of a water repellent in a smaller amount than the catalyst layer and a pore-forming agent in a smaller amount relative to the second catalyst layer on the surface of the second catalyst layer and drying the mixture; , a step of forming a first matrix layer by coating and drying a mixture of a matrix powder material and a binder on the surface of the third catalyst layer formed in the above step; A step of pre-calcining the electrode/matrix combination on which the catalyst layer and the first matrix layer have been formed, a step of main firing of the pre-fired electrode/matrix combination, and a step of relatively firing the matrix powder material and the first matrix layer. forming a second matrix layer by coating and drying a mixture with a large amount of a binder on the surface of the first matrix layer; Electrode with matrix layer formed
1. A method for producing an electrode/matrix assembly for a fuel cell, comprising the step of final firing the matrix assembly at a lower temperature than the main firing. 14 Preliminary firing is performed at a temperature of 150 to 280°C, main firing is performed at a temperature of 310 to 370°C, and final firing is performed at a temperature of 150 to 280°C.
14. The method of manufacturing an electrode/matrix assembly for a fuel cell according to claim 13, wherein the manufacturing method is carried out at a temperature of 150 to 320°C.