JP3271410B2 - Fuel cell and its solid polymer electrolyte membrane and electrode - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel cell having an opposed electrode and a solid polymer electrolyte membrane, wherein the solid polymer electrolyte membrane is sandwiched between the electrodes, and a catalyst which is located between the opposed electrodes and carries a catalyst. A solid polymer electrolyte membrane sandwiched between the electrodes with a catalyst layer made of conductive particles interposed therebetween, and a catalyst layer made of conductive particles formed of an electrode substrate having gas diffusivity and carrying a catalyst interposed therebetween. And an electrode for sandwiching the electrolyte.

[0002]

2. Description of the Related Art In a fuel cell using a solid polymer electrolyte membrane and electrodes (solid polymer electrolyte type fuel cell), a catalyst layer for accelerating an electrode reaction is used in combination, and both membrane surfaces of the solid polymer electrolyte membrane are used. A solid polymer electrolyte membrane is sandwiched between electrodes with a catalyst layer interposed therebetween. In producing such a fuel cell, a solid polymer electrolyte membrane, a catalyst layer, and an electrode are pot-pressed. The electrode reactions that proceed at the anode (oxygen electrode) and cathode (hydrogen electrode) of such a fuel cell are as follows. Cathode (hydrogen ^{_{electrode): 2H 2 → 4H + +}} 4e - ... anode (oxygen ^{electrode): 4H + + 4e - +} O 2 → 2H 2 O ...

Then, the hydrogen ions generated by the reaction formula at the cathode permeate (diffuse) through the solid polymer electrolyte membrane in the hydrated state of H ⁺ ( _{xH 2} O) to reach the anode, and the reaction formula proceeds. You do it. The cathode is supplied with hydrogen (gas) necessary for the reaction, and the anode is supplied with oxygen (gas). The catalyst layer is formed by aggregating and laminating conductive particles, such as carbon particles, carrying a catalyst such as platinum.

During operation of the above-described fuel cell, oxygen may be mixed in the hydrogen gas supplied to the cathode for some reason. For example, when slight damage, cracks, or the like occur in a hydrogen gas supply pipe due to collision of foreign matter or the like, the atmosphere flows into the pipe, and oxygen in the atmosphere mixes with the hydrogen gas. Also,
Oxygen may be mixed in a hydrogen gas supply device, for example, a lower alcohol reformer. Alternatively, oxygen may remain around the cathode due to poor sealing or deterioration of the seal between the electrode and the solid polymer electrolyte membrane in the fuel cell.

[0005] It is rare that such a situation occurs, but when oxygen is present at the cathode, it is expected that hydrogen combustion (reaction between hydrogen and oxygen) will occur at the cathode. Such combustion is considered to occur at the outer peripheral edge of the catalyst layer that promotes the electrode reaction, and when combustion occurs at the outer peripheral edge, the heat generated at that time damages the solid polymer electrolyte membrane,
There is a possibility that the battery performance may be reduced or the operation may be stopped.

In order to avoid such a situation, Japanese Patent Application Laid-Open No. HEI 5-174845 discloses a technique in which a resin film such as a fluororesin is provided between a solid polymer electrolyte membrane and an electrode so as to overlap the periphery of the electrode. Proposed.

[0007]

However, even if the above-mentioned resin film is provided, as shown in FIG. 11, the catalyst layer 100 made of carbon particles carrying the catalyst and the electrode 1
02 and the solid polymer electrolyte membrane 104 by hot pressing, the gap 10 between the inner peripheral edge of the resin coating 106 and the catalyst layer 100 depends on the thickness of the resin coating 106.
8 may occur. In such a case, if the above-described combustion occurs in the gap 108, damage to the solid polymer electrolyte membrane 104 cannot be avoided. Further, the catalyst layer 100
The heat generated by the combustion at the outer peripheral edge of the
6, if the coating is damaged by heat, the solid polymer electrolyte membrane 104 will eventually be damaged. That is, even if the resin coating is provided, the solid polymer electrolyte membrane, and hence the fuel cell, sometimes lacks durability.

The present invention has been made to solve the above problems, and has as its object to improve the durability of a solid polymer electrolyte membrane in a fuel cell.

[0009]

According to a first aspect of the present invention, there is provided a fuel cell comprising: a fuel cell having an electrode and a solid polymer electrolyte membrane facing each other; A fuel cell in which an electrolyte membrane is sandwiched between electrodes,
Between the solid polymer electrolyte membrane and the electrode, a catalyst layer composed of conductive particles carrying a catalyst, and a catalyst adjacent region which surrounds the catalyst layer along its outer peripheral edge and partitions the region occupied by the catalyst layer. And a fire-resistant layer on which particles having fire resistance are laid.

On the other hand, in the solid polymer electrolyte membrane according to the second aspect, the solid polymer electrolyte is sandwiched between the electrodes with a catalyst layer made of conductive particles carrying a catalyst interposed therebetween. A fire-resistant film, comprising: a catalyst contact area where the catalyst layer is in contact with the surrounding area of the catalyst along the outer peripheral edge of the area; The gist is to provide a layer.

In order to achieve the above-mentioned object, the means adopted by the present invention for the electrode is, in the electrode according to the third aspect, formed from an electrode substrate having gas diffusibility and comprising conductive particles carrying a catalyst. An electrode sandwiching an electrolyte with a catalyst layer interposed therebetween, the catalyst layer surrounding the catalyst layer facing the electrolyte along the outer peripheral edge thereof and a catalyst-adjacent region defining a region occupied by the catalyst layer; The main point is to provide a fireproof layer formed by laying.

[0012]

In the fuel cell according to the first aspect of the present invention, the laid area of the refractory layer provided between the solid polymer electrolyte membrane and the electrode surrounds the catalyst layer along its outer peripheral edge and occupies the catalyst layer. The region was defined as an adjacent region to the catalyst. Therefore, in combination with the fact that the refractory layer is laid with particles having fire resistance (fire-resistant particles), the conductive particles of the catalyst layer and the fire-resistant layer of the fire-resistant layer are formed at the outer periphery of the catalyst layer made of conductive particles. Contact with conductive particles. Therefore, a gap is not inadvertently left between the outer peripheral edge of the catalyst layer and the refractory layer, and the refractory layer blocks heat when a reaction between hydrogen and oxygen occurs at the outer peripheral edge of the catalyst layer.

[0013] In the solid polymer electrolyte membrane according to the second aspect,
The laying area of the refractory layer was defined as an area surrounding the catalyst contact area of the catalyst layer in contact with the membrane surface of the solid polymer electrolyte membrane along the outer peripheral edge thereof and defining the catalyst contact area. Therefore, in combination with the fact that the refractory layer is laid with particles having fire resistance (fire-resistant particles), the conductive particles of the catalyst layer and the fire-resistant layer of the fire-resistant layer are formed at the outer periphery of the catalyst layer made of conductive particles. Contact with conductive particles. Therefore, a gap is not inadvertently left between the outer peripheral edge of the catalyst layer and the refractory layer, and the refractory layer blocks heat when a reaction between hydrogen and oxygen occurs at the outer peripheral edge of the catalyst layer.

According to the third aspect of the present invention, the laying area of the refractory layer surrounds the catalyst layer facing the electrolyte along the outer peripheral edge thereof and defines a region occupied by the catalyst layer. For this reason, in combination with the fact that the refractory layer is laid with the particles having fire resistance, the conductive particles of the catalyst layer and the refractory particles of the fire layer are in contact with each other at the outer peripheral edge of the catalyst layer made of the conductive particles. Let it. Therefore, a gap is not inadvertently left between the outer peripheral edge of the catalyst layer and the refractory layer, and when the electrolyte is sandwiched with the catalyst layer interposed, the solid polymer electrolyte membrane has a catalyst layer on the membrane surface. The catalyst layer is surrounded by the refractory layer of the electrode by bringing the refractory particles of the refractory layer of the electrode into contact with the outer peripheral edge. As a result, heat generated when a reaction between hydrogen and oxygen occurs at the outer peripheral edge of the catalyst layer is blocked by the refractory layer of the electrode.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In order to further clarify the structure and operation of the present invention described above, preferred embodiments of the present invention will be described below. FIG. 1 is a schematic view of a cell structure of a fuel cell (polymer electrolyte fuel cell) in this embodiment. As shown in the figure, the cell has an electrolyte membrane 10 at the center thereof, and on both sides thereof, an anode-side catalyst reaction layer 12 and a cathode-side catalyst reaction layer 14 which are in close contact with the membrane surface of the electrolyte membrane 10; The anode 20 and the cathode 30 which are in close contact with each other, current collectors 40 and 42 which are in close contact with the respective poles and are sealed with the electrolyte membrane 10 by the gas seal 15, and a separator 44 which partitions each cell.

The anode 20 and the cathode 30 are made of carbon cloth obtained through a woven cloth of carbon fibers or the like, and are incorporated in recesses 46 formed in the current collectors 40 and 42, respectively. Around the anode-side catalyst reaction layer 12 and the cathode-side catalyst reaction layer 14, a refractory layer 1 surrounding these catalyst reaction layers is formed.
6 are provided in close contact with the electrolyte membrane 10 and the respective electrode surfaces. The steps of forming the anode-side catalytic reaction layer 12, the cathode-side catalytic reaction layer 14, and the refractory layer 16 will be described later.

The electrolyte membrane 10 is a solid polymer electrolyte membrane of a polymer cation exchange membrane having a sulfone group as an ion exchange group for hydrogen ions (hereinafter, also simply referred to as a cation exchange membrane). Selectively transmits along the direction. More specifically, the electrolyte membrane 10 is a cation exchange membrane (for example, a perfluorocarbon sulfonic acid polymer membrane (trade name: Nafion membrane, manufactured by Du Pont)) made of a fluorosulfonic acid polymer resin. , And its film thickness is 100 μm.

The anode-side catalyst reaction layer 12 and the cathode-side catalyst reaction layer 14 are interposed between the anode 20, the cathode 30, and the electrolyte membrane 10, which will be described later. Surface and each electrode surface. The anode-side catalytic reaction layer 12 and the cathode-side catalytic reaction layer 14 were agglomerated and laminated such that carbon particles supporting 20 wt% of platinum as a catalyst were in a ratio of 0.4 mg / cm ^{2 on} the surface of the electrolyte membrane 10. This is a carbon particle aggregation layer, which is applied to the surface of the electrolyte membrane 10 or the surface of the electrode film prior to hot pressing, and is manufactured through subsequent hot pressing. This manufacturing process will be described later.

For the anode 20 and the cathode 30, a plain-woven carbon cloth (about 0.4 mm in thickness) is used as an electrode substrate, and carbon particles which have been subjected to a water-repellent treatment with a fluororesin or the like are applied to the carbon cloth. It is made by embedding.

The current collectors 40 and 42 are formed of porous and gas-permeable porous carbon and have a porosity of 40 to 80%. The current collector 40
In addition, a flow path 41 is formed as a flow path for an oxygen-containing gas as an anode fuel and a water collection path for water generated by the anode 20. A current collector 42 is provided with a hydrogen-containing gas as a cathode fuel. A flow path 43 for a mixed gas (humidified hydrogen gas) of water and water vapor is formed. The flow paths 41 and 43 are open at both ends of the cell (the front side and the back side of the paper surface of FIG. 1) at the end faces of the respective current collectors, and supply the fuel gas from the openings. The state of this opening is indicated by a dashed line on the upper and lower end surfaces of the cell in the figure.

The separator 44 is made of gas-impermeable carbon which has been made gas-impermeable by compressing carbon, and has an electrolyte membrane 10, an anode 20, a cathode 30, a current collector 40,
A partition wall is formed when the cells constituted by 42 are stacked.
In the present embodiment, the current collectors 40 and 42 and the separator 44 are formed separately, but the current collector 40 and the separator 44 are integrally formed of gas impermeable carbon, or the current collector 42 and the separator 44 are formed integrally. Are preferably formed integrally with the gas-impermeable carbon, and the current collectors 40 and 42 and the separator 44 are integrally formed with the gas-impermeable carbon.

Next, the steps of forming the anode-side catalytic reaction layer 12, the cathode-side catalytic reaction layer 14, and the refractory layer 16 and the steps of manufacturing a fuel cell (cell) will be described. First, a carbon cloth 50 (a product that has been coated with water-repellent carbon particles) to be the anode 20 and the cathode 30 is prepared, and the following steps are sequentially performed. At this time, the paste for forming the next catalyst layer and the paste for forming the refractory layer are prepared in advance.

The paste for forming the catalyst layer is made of carbon particles (Pt 0.4 mg) supporting 20 wt% of platinum as a catalyst.
/ Cm ² ) is gradually added to a cation exchange resin solution, for example, a fluorinated sulfonic acid polymer resin solution of the same quality as the electrolyte membrane 10 (a solution in which a solid content of 5 wt% of the resin is mixed with a mixed solution of propanol and water). In addition, resin solid content is 1mg / c
It is a carbon paste obtained by mixing carbon particles to a value equivalent to m ² . As for the paste for forming the refractory layer, single carbon particles not carrying a catalyst are gradually added to the above-mentioned fluorine-based sulfonic acid polymer resin solution as in the case of the paste for forming the catalyst layer, and the resin solid content is reduced. 1mg / c
It is a carbon paste obtained by mixing carbon particles to a value equivalent to m ² .

First, as shown in FIG. 2A, a paste for forming a catalyst layer is applied to carbon particles carrying platinum (carbon particles carrying platinum) over the catalyst layer forming region 52 at the center of the carbon cloth 50. Is applied at a rate of 0.4 mg / cm ² . After applying this paste,
Over the catalyst layer forming area 52, the platinum-supported carbon particles were 0.4 m thick via the fluorinated sulfonic acid polymer resin solution.
Aggregate and laminate at a rate of g / cm ² .

Next, as shown in FIG. 2 (B), a region other than the catalyst layer forming region 52, that is, a catalyst layer adjacent region 5 which surrounds and partitions the catalyst layer forming region 52 along its outer periphery.
Then, a paste for forming a refractory layer is applied over a period of 4 so that the carbon particles have a ratio of 0.4 mg / cm ² . After application of the paste, the carbon particles are aggregated and laminated at a rate of 0.4 mg / cm ² via the fluorine-based sulfonic acid polymer resin solution over the catalyst layer adjacent region 54. Then, the platinum-carrying carbon particles and the carbon particles come into contact with each other at the division line in each region.

Each of the above-described steps is performed using two carbon cloths 5
0, one as the anode 20 and the other as the cathode 30. In FIG. 2B, the catalyst layer adjacent region 54 is depicted at a slight distance from the outer peripheral edge of the carbon cloth 50. However, the catalyst layer adjacent region 54 is different from the catalyst layer forming region 52.
What is sufficient is to surround and partition along the outer periphery, and it does not matter whether or not it reaches this outer peripheral edge.

Since the anode 20 and the cathode 30 have been manufactured in this way, the anode 20 and the cathode 30 are incorporated into the recesses 46 of the current collectors 40 and 42 such that the paste application side is on the outside. Thereafter, the electrolyte membrane 10 is sandwiched between the anode 20 and the cathode 30 with the anode-side catalyst reaction layer 12 and the cathode-side catalyst reaction layer 14 interposed therebetween, and these are hot-pressed (120 ° C., 120 ° C.).
100 kg / cm ² ). Then, the current collectors 40 and 42
Then, the separators 44 are brought into close contact with each other to complete an assembled fuel cell (cell). That is, the platinum-carrying carbon particles are aggregated and laminated over the catalyst layer forming region 52 to form the anode-side catalyst reaction layer 12 or the cathode-side catalyst reaction layer 14, and the carbon particles that do not carry the catalyst cover the catalyst layer adjacent region 54. The refractory layer 16 is formed by agglomeration and lamination. Then, the refractory layer 16 comes into contact with and surrounds the cathode-side catalytic reaction layer 14 at the periphery thereof.

In the fuel cell configured as described above, when the fuel gas (humidified hydrogen gas, oxygen gas) is supplied to the respective electrodes from the flow paths 41, 43 of the current collectors 40, 42, the anode-side catalytic reaction layer 12, In the cathode-side catalytic reaction layer 14, the reaction represented by the above-described equation (1) is advanced to generate electric energy.

Next, the performance evaluation of the completed fuel cell of this embodiment will be described. Comparative fuel cell (comparative example)
Shows a structure in which the above-mentioned paste for forming a catalyst layer is applied over the entire surface of the carbon cloth 50 to form an anode-side catalyst reaction layer 12 and a cathode-side catalyst reaction layer 14. In other words, the fuel cell in comparison with the fuel cell of the present embodiment is common in that it has electrodes and a catalytic reaction layer, the thickness of the electrolyte membrane 10 and the like, and the anode-side catalytic reaction layer 12 and the cathode-side catalytic reaction layer 14 The configuration differs only depending on the presence or absence of the surrounding refractory layer 16.

The durability of both the fuel cell of the embodiment fuel cell and the fuel cell of the comparative example under adverse conditions which do not occur during normal operation was examined. That is, 30 vol% of air is supplied from the flow path 43 of the current collector 42 on the cathode side (oxygen 6 vol.
%), And the time elapsed since the start of the supply of the oxygen-rich mixed hydrogen gas and the change in the fuel cell output (cell voltage) were examined. . The mixing ratio of oxygen during normal operation is 1 vol% or less.

In the fuel cell of the comparative example, the cell voltage sharply dropped about 1 minute after the supply of the oxygen-excess mixed hydrogen gas was started, and became 0 after about 2 to 30 minutes.
On the other hand, in the example fuel cell, even after about one hour, only about 3% of the cell voltage obtained during the normal operation was reduced.

When a sharp decrease in cell voltage of the fuel cell of the comparative example was observed, both fuel cells were disassembled and the state of the electrolyte membrane 10 was examined. Then, in the comparative example fuel cell,
In the vicinity of the outer peripheral edge of the cathode-side catalytic reaction layer 14, the electrolyte membrane 1
Burning and deformation due to heat of combustion (a hole was formed in the film and cross leak occurred between the electrodes) was observed on the film surface of No. 0. On the other hand, in the example fuel cell, no abnormality such as scorching or deformation was observed.

Accordingly, the refractory layer 1 surrounding the anode-side catalyst reaction layer 12 and the cathode-side catalyst reaction layer 14 in contact with the outer peripheral edge thereof.
According to the example fuel cell having 6 in the hydrogen gas, 30
Even under the poor condition that air of vol% is mixed, the electrolyte membrane 10 does not cause abnormality for a long time. For this reason, according to the example fuel cell, the durability of the electrolyte membrane 10 and thus the fuel cell itself can be improved.

The improvement in durability can be explained as follows. In the fuel cell of the embodiment, as shown in the schematic diagram of FIG.
At the boundary (represented by a dotted line in the figure) between the
Platinum-carrying carbon particles are in contact with carbon particles that do not carry platinum. Then, the outer peripheral edge of the cathode-side catalytic reaction layer 14 is completely covered with the carbon particles of the refractory layer 16. In such a state, the current collector 4 on the cathode side
Even if the oxygen-excess mixed hydrogen gas is supplied from the second flow path 43 as shown by the arrow in the figure and the combustion of hydrogen occurs due to the catalytic action of platinum, the heat generated at the outer peripheral edge of the cathode-side catalytic reaction layer 14 is Regardless of the presence or absence of the gap 15a on the end face of the seal 15,
The electrolyte membrane 10 shielded by the individual carbon particles of the refractory layer 16
Does not reach directly. Further, since the carbon particles of the refractory layer 16 do not carry platinum, the catalytic action does not work, and the refractory layer 16 itself does not transmit combustion heat to the electrolyte membrane 10.
Therefore, it can be said that abnormalities such as deformation due to heat hardly occur in the electrolyte membrane 10 and the durability is rich.

On the other hand, in the fuel cell of the comparative example, since the refractory layer 16 does not exist, as shown in the schematic diagram of FIG.
The heat generated at the outer peripheral edge of the cathode-side catalytic reaction layer 14 is
Indirectly via gas seal 15 or gas seal 1
If there is a gap 15a at the end face 5, the air is directly transmitted to the electrolyte membrane 10 from this gap 15a. For this reason, the electrolyte membrane 1 by heat
An abnormality of 0 tends to occur, resulting in a lack of durability. However, since it is not practical to completely eliminate the gap 15a on the end face of the gas seal 15 because the formation process of the cathode-side catalytic reaction layer 14 is complicated, the gap 15a is not provided in the electrolyte membrane 10.
Heat is transmitted directly from the

Next, a second embodiment will be described. The fuel cell of the second embodiment is different from the fuel cell of the first embodiment in the application area of the paste for forming the refractory layer for forming the refractory layer 16. In the second embodiment, first, similarly to the first embodiment, a paste for forming a catalyst layer is applied over the catalyst layer forming region 52 at the center of the carbon cloth 50 (FIG. 2A). Next, as shown in FIG. 5, a paste for forming a refractory layer is applied over the catalyst layer interference adjacent region 56 having a region inside the catalyst layer forming region 52 along the outer periphery thereof. After the application of the paste, the platinum-carrying carbon particles are aggregated and stacked in the catalyst layer adjacent region 54, and the catalyst layer adjacent region 54 becomes the anode-side catalyst reaction layer 12 and the cathode-side catalyst reaction layer 14. On the other hand, the carbon particles aggregate and accumulate in the catalyst layer interference adjacent area 56, and the catalyst layer interference adjacent area 56 becomes the refractory layer 16. As shown in FIG. 5, the refractory layer 16 overlaps the anode-side catalytic reaction layer 12 and the cathode-side catalytic reaction layer 14 along the outer peripheral edge thereof with a width of d.

The thus prepared anode 20 and cathode 30 are
Hot pressing is performed in the same manner as in the first embodiment with the electrolyte membrane 10 interposed therebetween. In the second embodiment through the above steps, the periphery of the refractory layer 16 is as follows. That is, as shown in the schematic diagram of FIG. 6, on the lower surface of the outer peripheral edge of the cathode-side catalytic reaction layer 14, a catalyst lower surface refractory layer 16 a extending from the refractory layer 16 is formed. I have. For this reason,
At the boundaries (shown by dotted lines in the figure) between the cathode-side catalytic reaction layer 14 and the refractory layer 16 and the catalyst lower-side refractory layer 16a, the platinum-carrying carbon particles and the carbon particles that do not carry platinum come into contact. Then, the outer peripheral edge of the cathode-side catalytic reaction layer 14 is completely covered with carbon particles including the lower surface thereof.

Therefore, even in the fuel cell of the second embodiment described above, the heat generated at the outer peripheral edge of the cathode-side catalytic reaction layer 14 due to the combustion of hydrogen is reduced to the individual levels of the refractory layer 16 and the lower catalyst refractory layer 16a. It is shielded by the carbon particles and does not directly reach the electrolyte membrane 10. As a result, according to the fuel cell of the second embodiment, abnormalities such as deformation due to heat are unlikely to occur in the electrolyte membrane 10, and the durability of the fuel cell itself as well as the electrolyte membrane 10 can be improved. In the second embodiment, the paste application range for forming the catalyst layer and the refractory layer is set to a width d.
, It is possible to more reliably cover the outer peripheral edge of the cathode-side catalytic reaction layer 14 with the carbon particles of the refractory layer 16 without gaps, which is effective in improving durability.

Next, in order to form the anode-side catalytic reaction layer 12, the cathode-side catalytic reaction layer 14 and the refractory layer 16, an embodiment in which a paste for forming a catalyst layer and a paste for forming a refractory layer are applied to the electrolyte membrane 10 ( Third and fourth embodiments) will be described. In the third and fourth embodiments, the paste is applied to the electrolyte membrane 10, and the order of application is different.

That is, in the fuel cell of the third embodiment, over the catalyst layer forming region 52 at the center of both membrane surfaces of the electrolyte membrane 10,
A paste for forming a catalyst layer is applied, and then, over a catalyst layer adjacent region 54 surrounding the catalyst layer formation region 52,
A paste for forming a refractory layer is applied (see FIG. 2). That is, in the third embodiment, the paste for forming the refractory layer and the catalyst layer is applied to the electrolyte membrane 10 in the first embodiment.
However, the application range and application order of each paste are the same.

After the paste is applied, the platinum-supported carbon particles are aggregated and laminated on the surface of the electrolyte membrane 10 in the catalyst layer adjacent region 54, and the catalyst layer adjacent region 54 becomes the anode-side catalyst reaction layer 12 and the cathode side. It becomes the catalyst reaction layer 14. On the other hand, in the catalyst layer interference adjacent area 56, carbon particles are aggregated and laminated on the membrane surface of the electrolyte membrane 10, and the catalyst layer interference adjacent area 56 is
It becomes 6. Then, when the electrolyte membrane 10 is sandwiched between the anode 20 and the cathode 30 and hot pressed, the refractory layer 16
As shown in FIG. 3, the platinum-carrying carbon particles and the platinum-carrying carbon particles are not in contact with each other at the boundary between the cathode-side catalytic reaction layer 14 and the boundary thereof. For this reason, since the outer peripheral edge of the cathode-side catalytic reaction layer 14 is covered with the carbon particles of the refractory layer 16 without gaps, even in the fuel cell of the third embodiment, the cathode-side catalytic reaction is caused by the combustion of hydrogen. Layer 14
The heat generated at the outer peripheral edge is blocked by individual carbon particles of the refractory layer 16 and is not directly transmitted to the electrolyte membrane 10. As a result,
According to the fuel cell of the third embodiment, abnormalities such as deformation due to heat are less likely to occur in the electrolyte membrane 10, and the durability of the fuel cell itself as well as the electrolyte membrane 10 can be improved.

In the fuel cell of the fourth embodiment, first, a paste for forming a refractory layer is applied to both surfaces of the electrolyte membrane 10. The coating range overlaps the catalyst layer forming region 52 at the center of both membrane surfaces of the electrolyte membrane 10 with a width d along the outer peripheral edge thereof, and enters the catalyst layer forming region 52 along the outer periphery inside the catalyst layer forming region 52. This is the interference adjacent area 56 (see FIG. 5). Next, a paste for forming a catalyst layer is applied to the catalyst layer formation region 52 which partially overlaps the catalyst layer interference adjacent region 56 and falls inside (see FIG. 5). In other words, this fourth
In the embodiment, the application range of the paste for forming the refractory layer and the catalyst layer is the same as that of the second embodiment, but the application target and the application order are different.

After the paste is applied, as shown in FIG. 6, the refractory layer 16 having the catalyst lower surface refractory layer 16a penetrating into the lower surface of the outer peripheral edge of the cathode side catalytic reaction layer 14 is used. Are surrounded by the cathode-side catalytic reaction layer 14.
Is covered with carbon particles without any gaps, including the lower surface thereof.

Therefore, even in the fuel cell of the fourth embodiment, the heat generated at the outer peripheral edge of the cathode-side catalytic reaction layer 14 due to the combustion of hydrogen is transferred to the refractory layer 16 and the lower catalyst refractory layer 16a.
And is not directly transmitted to the electrolyte membrane 10. As a result, according to the fuel cell of the fourth embodiment, abnormalities such as deformation due to heat are unlikely to occur in the electrolyte membrane 10, and the durability of the fuel cell itself as well as the electrolyte membrane 10 can be improved.

Next, a fifth embodiment will be described. In the fifth embodiment, first, as shown in FIG. 7, the anode-side catalyst reaction layer 12 and the cathode-side catalyst reaction are formed over substantially the entire surface of one side of the carbon cloth 50, that is, in a range slightly deviated from the outer periphery of the carbon cloth. A paste for forming a catalyst layer is applied over a catalyst layer containing region 58 including a region to be the layer 14 (FIG. 7).
(A)). Next, the paste for forming the refractory layer is applied so as to partially overlap the applied paste for forming the catalyst layer over the catalyst layer adjacent region 54 surrounding the catalyst layer formation region 52 at the center of the carbon cloth 50 (FIG. 7). (B)).
That is, the fifth embodiment is different from the first embodiment in that the application region of the paste for forming the catalyst layer is the catalyst layer containing region 58 including the catalyst layer formation region 52. In this case, the catalyst layer containing region 58 may be the entire surface of one side of the carbon cloth 50.

Thereafter, similarly to the above embodiments, the fuel cell is completed by hot pressing with the electrolyte membrane 10 interposed therebetween. As shown in the schematic diagram of FIG. 8, around the refractory layer 16 in the fifth embodiment through the above steps, as shown in the schematic diagram of FIG.
a, on the lower surface of the outer peripheral edge of the cathode-side catalytic reaction layer 14,
It is formed to penetrate the lower surface in a wider range than in the case of the second embodiment of FIG.

Therefore, even in the fuel cell of the fifth embodiment described above, the heat generated at the outer peripheral edge of the cathode-side catalytic reaction layer 14 due to the combustion of hydrogen is reduced to the individual levels of the refractory layer 16 and the lower catalyst refractory layer 16a. It is shielded by the carbon particles and does not directly reach the electrolyte membrane 10. As a result, according to the fuel cell of the fifth embodiment, abnormalities such as deformation due to heat are unlikely to occur in the electrolyte membrane 10, and the durability of the fuel cell itself as well as the electrolyte membrane 10 can be improved. In the fifth embodiment, the paste for forming the catalyst layer and the paste for forming the refractory layer are applied over a wide range, so that the outer peripheral edge of the cathode-side catalytic reaction layer 14 formed by the carbon particles of the refractory layer 16 can be further improved. Covering can be reliably performed without any gaps, which is effective in improving durability. Furthermore,
When the paste for forming the catalyst layer is applied, the applied area is roughly set as the catalyst layer containing area 58 and the catalyst layer forming area 52 is formed.
Need not be considered. Therefore, according to the fifth embodiment,
The application step can be simplified.

The fifth embodiment can be modified so that the paste is applied to the electrolyte membrane 10 and the order of applying the paste is changed. That is, the catalyst layer adjacent region 54 surrounding the catalyst layer formation region 52 is provided on both membrane surfaces of the electrolyte membrane 10.
, A paste for forming a refractory layer is applied (FIG. 7 (B)).
Next, a paste for forming a catalyst layer is applied over the catalyst layer containing region 58 including the catalyst layer forming region 52 (see FIG. 7A). Then, the electrolyte membrane 10 is hot-pressed while being sandwiched between carbon cloths 50 serving as the anode 20 and the cathode 30. Also in this modified example, as shown in the schematic diagram of FIG. 8, the fire-resistant layer 16 having the catalyst lower-surface fire-resistant layer 16a can be obtained, so that the same effect as in the fifth embodiment can be obtained.

Next, a sixth embodiment will be described. In the sixth embodiment, the anode-side catalytic reaction layer 12 and the cathode-side catalytic reaction layer 14 are formed by applying paste to the respective carbon cloths 50, and the refractory layer 16 is formed by applying paste to the electrolyte membrane 10. . That is, as shown in FIG.
A paste for forming a catalyst layer is applied over the catalyst layer formation region 52 at the center of the carbon cloth 50 (FIG. 9A), and both electrodes (anode 20 and cathode 30) are prepared. On the other hand, a paste for forming a refractory layer is applied to both membrane surfaces of the electrolyte membrane 10 over a catalyst layer adjacent area 54 surrounding the catalyst layer formation area 52 at the center of the membrane surface of the electrolyte membrane 10 (FIG. 9B). , Electrolyte membrane 1
Prepare 0. After that, as in each of the above-described embodiments,
The fuel cell is completed by hot pressing the electrolyte membrane 10 with both electrodes (anode 20 and cathode 30) interposed therebetween. Around the refractory layer 16 in the sixth embodiment through the above steps, the outer peripheral edge of the cathode-side catalytic reaction layer 14 is made of carbon particles of the refractory layer 16 without gaps in the same manner as in the first embodiment described above (see FIG. 3). Will be covered. The same effects as in the first embodiment can be obtained.

In the sixth embodiment, a paste for forming a catalyst layer is applied to both surfaces of the electrolyte membrane 10 over the catalyst layer formation region 52 (see FIG. 9A). It can be modified so as to apply a paste for forming a refractory layer over the catalyst layer adjacent region 54 (see FIG. 9B). Further, the application area of the catalyst layer forming paste on the carbon cloth 50 may be a catalyst layer containing area 58 wider than the catalyst layer forming area 52 or the entire surface of the carbon cloth 50 (see FIG. 7A). The application region of the paste for forming the refractory layer can be modified to be a catalyst layer interference adjacent region 56 that partially overlaps with the catalyst layer formation region 52 (see FIG. 5). As described above, when the paste for forming the catalyst layer is applied to the entire surface of the carbon cloth 50, around the outer peripheral edge of the cathode-side catalytic reaction layer 14, FIG.
As shown in FIG. 0, the refractory layer 16 having the catalyst lower surface refractory layer 16a penetrating to the lower surface thereof is formed, and the carbon particles in the range of the catalyst lower surface refractory layer 16a are buried in the membrane surface of the electrolyte membrane 10 by hot pressing. Cathode side catalytic reaction layer 1
4 is surrounded by carbon particles in the surface layer of the refractory layer 16 at the lower end of the outer peripheral edge. Even in this case, the heat generated at the outer peripheral edge of the cathode-side catalytic reaction layer 14 due to the combustion of hydrogen is reduced by the surface layer of the refractory layer 16 and the refractory layer 1 under the catalyst.
Since the individual carbon particles 6a do not directly transmit to the electrolyte membrane 10, the durability of the electrolyte membrane 10 as well as the fuel cell itself can be improved.

Although the embodiment of the present invention has been described above, the present invention is not limited to such an embodiment, and may be implemented in various modes without departing from the gist of the present invention. Of course.

For example, the paste for forming the refractory layer for forming the refractory layer 16 surrounding the anode-side catalytic reaction layer 12 and the cathode-side catalytic reaction layer 14 is a paste of water-repellent carbon particles. You can also. This is preferable because the refractory layer 16 exhibits water repellency, thereby removing water from the electrode and preventing the water from staying in the electrode. Further, carbon particles for forming the refractory layer 16 are replaced with other particles having fire resistance, for example, Al ₂ O _3.
(Alumina), BN (boron nitride), SiC (silicon carbide) or the like, or carbon particles for forming the anode-side catalyst reaction layer 12 and the cathode-side catalyst reaction layer 14 which have conductivity and corrosion resistance. Particles.

[0053]

As described above in detail, in the fuel cell according to the first aspect, the catalyst layer and the refractory layer provided between the solid polymer electrolyte membrane and the electrode are electrically connected to each other at the outer periphery of the catalyst layer. The particles are brought into contact with the refractory particles of the refractory layer. Therefore, in the fuel cell according to the first aspect, the fact that heat generated when a reaction between hydrogen and oxygen occurs at the outer peripheral edge of the catalyst layer is transmitted to the solid polymer electrolyte membrane between the outer peripheral edge of the catalyst layer and the refractory layer. The voids can be filled with these particles, thereby suppressing the refractory layer. As a result, according to the fuel cell of the first aspect, it is possible to improve not only the durability of the solid polymer electrolyte membrane but also the durability of the electrolyte membrane through suppression of deterioration of the solid polymer electrolyte membrane due to heat. .

In the solid polymer electrolyte membrane according to the second aspect,
The catalyst layer and the refractory layer that are in contact with the membrane surface of the solid polymer electrolyte membrane are brought into contact with the conductive particles of the catalyst layer and the refractory particles of the refractory layer at the outer periphery of the catalyst layer. Therefore, in the solid polymer electrolyte membrane according to claim 2, the gap between the outer peripheral edge of the catalyst layer and the refractory layer can be filled with the particles. Heat can be blocked when an oxygen reaction occurs. As a result, according to the solid polymer electrolyte membrane of the second aspect, the durability of the solid polymer electrolyte membrane in the fuel cell can be improved.

In the electrode according to the third aspect, when the electrolyte is sandwiched with the catalyst layer interposed, the outer periphery of the catalyst layer and the refractory layer of the electrode are formed on the membrane surface of the solid polymer electrolyte membrane. With the gaps filled with refractory particles, the catalyst layer is surrounded by the refractory layer of the electrode. As a result, according to the electrode of the third aspect, the durability of the solid polymer electrolyte membrane is improved by blocking the heat when the reaction between hydrogen and oxygen occurs at the outer peripheral edge of the catalyst layer with the refractory layer of the electrode. can do.

[Brief description of the drawings]

FIG. 1 is a schematic view of a cell structure of a fuel cell according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram for explaining a manufacturing process of the fuel cell according to the first embodiment.

FIG. 3 is a schematic diagram showing a state around an outer peripheral edge of a cathode-side catalytic reaction layer 14 in the fuel cell of the first embodiment.

FIG. 4 shows a cathode-side catalytic reaction layer 14 in a fuel cell of a comparative example.
FIG. 2 is a schematic diagram showing a state around an outer peripheral edge of the circumstance.

FIG. 5 is an explanatory diagram for explaining a manufacturing process of the fuel cell according to the second embodiment.

FIG. 6 is a schematic diagram showing a state around an outer peripheral edge of a cathode-side catalytic reaction layer 14 in the fuel cell of the second embodiment.

FIG. 7 is an explanatory diagram for explaining a manufacturing process of the fuel cell according to the fifth embodiment.

FIG. 8 is a schematic diagram showing a state around an outer peripheral edge of a cathode-side catalytic reaction layer in a fifth embodiment fuel cell.

FIG. 9 is an explanatory diagram for explaining a manufacturing process of the fuel cell according to the sixth embodiment.

FIG. 10 is a schematic view showing a state around an outer peripheral edge of a cathode-side catalytic reaction layer in a modification of the sixth embodiment.

FIG. 11 is an explanatory diagram for explaining a problem in a conventional fuel cell.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Electrolyte membrane 12 ... Anode side catalytic reaction layer 14 ... Cathode side catalytic reaction layer 15 ... Gas seal 15a ... Void 16 ... Refractory layer 16a ... Catalyst lower surface refractory layer 20 ... Anode 30 ... Cathode 50 ... Carbon cloth 52 ... Catalyst layer formation Area 54: catalyst layer adjacent area 56: catalyst layer interference adjacent area 58: catalyst layer containing area

Claims (3)

(57) [Claims] 1. A fuel cell comprising an opposed electrode and a solid polymer electrolyte membrane, wherein the solid polymer electrolyte membrane is sandwiched between electrodes, wherein a catalyst is provided between the solid polymer electrolyte membrane and the electrode. A catalyst layer made of conductive particles carrying the same, and a fire-resistant layer formed by laying fire-resistant particles in a catalyst-adjacent region surrounding the catalyst layer along its outer peripheral edge and defining a region occupied by the catalyst layer. A fuel cell comprising: 2. A solid polymer electrolyte membrane sandwiched between said electrodes with a catalyst layer made of conductive particles carrying a catalyst interposed therebetween, said catalyst being in contact with said catalyst layer. A solid polymer electrolyte, comprising a refractory layer formed by laying refractory particles on a membrane surface in a catalyst-adjacent region surrounding the contact region along an outer peripheral edge of the region and defining the catalyst contact region; film. 3. An electrode formed from an electrode substrate having gas diffusivity and sandwiching an electrolyte with a catalyst layer made of conductive particles carrying a catalyst interposed therebetween, wherein the catalyst layer facing the electrolyte is In a catalyst adjacent region surrounding the outer peripheral edge and defining a region occupied by the catalyst layer,
An electrode comprising a fire-resistant layer on which particles having fire resistance are laid.