JP2003092112A - Solid polymer fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solid polymer fuel cell uniformly keeping humidity distribution in a solid polymer electrolyte membrane and an oxidizing agent catalyst layer along the flow direction of oxidizing agent gas and in the direction from the inlet side to the outlet side. SOLUTION: This solid polymer fuel cell has a water evaporation control porous layer 30 between the oxidizing agent catalyst layer 29 and an oxidizing gas diffusion layer 31.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention uses a solid polymer membrane as an electrolyte layer, a fuel electrode is disposed on one of both sides of the electrolyte layer, and an oxidant electrode is disposed on the other side, and a fuel gas and an oxidant are disposed on each electrode. The present invention relates to a polymer electrolyte fuel cell that supplies electric energy to each gas to obtain electric energy by an electrochemical reaction, and more particularly to a polymer electrolyte fuel cell having an improved oxidizer electrode.

[0002]

2. Description of the Related Art A fuel cell using, for example, a solid polymer electrolyte membrane having proton conductivity as an electrolyte can have a compact shape, has a high power output, and further simplifies the system. Since it can be operated, it is drawing attention as a power source for portable and vehicle applications in a wide range of fields in addition to stationary distributed power sources.

Thus, as shown in FIG. 12, the solid polymer electrolyte fuel cell, which has received a great deal of attention, has a solid polymer electrolyte membrane 1 arranged in the center and both sides of the solid polymer electrolyte membrane 1. , A fuel electrode 4 provided with a fuel catalyst layer 2 and a fuel gas diffusion layer 3 on one side, and an oxidant electrode 7 provided with an oxidant catalyst layer 5 and an oxidant gas diffusion layer 6 on the other side, and each electrode A fuel cell 9 having a fuel gas flow groove 8 and a oxidant separator 11 having an oxidant gas flow groove 10 are arranged outside the fuel cells 4, 7 to form a single cell (single cell) 12.

In the polymer electrolyte fuel cell having such a structure, the electromotive force of one unit cell 12 is as low as 1 V or less, and therefore, as shown in FIG. Dozens to hundreds of cells 1
2 are stacked to form the fuel cell stack 13, and
Since it is necessary to suppress the temperature rise of the fuel cell stack 13 during the exothermic reaction of each of the electrodes 4 and 7, as shown in FIG. 12, the cooling plate 15 provided with the coolant circulation groove 14 is provided for each single cell or each plurality of cells. Has been inserted into.

On the other hand, as the solid polymer electrolyte membrane 1, for example, perfluorocarbon sulfonic acid (for example, Nafion membrane manufactured by DuPont, USA) which is a proton exchange membrane is often used. This membrane has a hydrogen ion exchange group in the molecule and functions as an ion-conducting electrolyte when it is saturated with water, and also has a function of separating the fuel gas and the oxidant gas. Therefore, in order to obtain high battery characteristics, it is important to make the solid polymer electrolyte membrane 1 contain water in a saturated state or a state close to saturation.

On the other hand, the fuel electrode 4 and the oxidant electrode 7 are
As shown in FIG. 12, a fuel catalyst layer 2 and an oxidant catalyst layer 5 each containing a substance having a catalytic activity, a fuel gas diffusion layer 3 and an oxidant that promote diffusion of a reaction gas into each catalyst layer 2, 5. The gas diffusion layer 6 is provided. Each diffusion layer 3, 6
For example, a cloth shape or a plate shape containing carbon fibers is used. Each of the plate-shaped diffusion layers 3 and 6 has a function of supporting the catalyst layer. The carbon gas diffusion layer has good conductivity and also has a function as a current collector.

In a polymer electrolyte fuel cell having another structure, as shown in FIG. 14, a fuel catalyst layer 2 and an oxidant catalyst layer 5, a fuel gas diffusion layer 3 and an oxidant gas diffusion layer 6 are provided. There is also one in which a fuel gas porous layer 16 and an oxidant gas porous layer 17 are interposed between each of these (for details, see US Pat. No. 5,620,807).

In this embodiment, the fuel gas diffusion layer 3 and the oxidant gas diffusion layer 6 are provided with respective porous layers 16 and 17 each having a different porosity, so that the fuel gas is moved to the fuel electrode 4. And migration of oxidant gas to oxidant electrode 7, or oxidant electrode 7 during electrode reaction
It is intended to facilitate the discharge of the water generated in the above into the oxidant gas flow groove 10, and as a result, to improve the electromotive force in the high current density region.

Further, in another invention which is an improvement of this embodiment, a coating layer provided with an ion exchange resin is provided on the oxidant gas porous layer 17 as seen in, for example, Japanese Patent Laid-Open No. 2001-93544. For example, Japanese Patent Laid-Open No. 9-245
As can be seen in Japanese Patent Publication No. 800, there is one in which the oxidant gas diffusion layer 6 is made hydrophilic and the surface of the oxidant catalyst layer 5 in contact with the oxidant gas diffusion layer 6 is coated with a water-repellent substance.
Both are intended to improve water retention.

On the other hand, the fuel separator 9 has a fuel gas flow groove 8 for flowing the fuel gas to the fuel electrode 4, and the oxidant separator 11 has an oxidant gas flow groove 10 for flowing the oxidant gas to the oxidant electrode 7. They are provided respectively, and are discharged to the outside through the oxidant gas flow groove 10 generated in the oxidant electrode 7 during the electrode reaction.

Both separators 9 and 11 are electrically conductive,
Since it is required to have excellent airtightness, heat resistance, workability, strength, etc., for example, either a corrosion-resistant metal plate, a high-density carbon plate, or a composite plate of carbon and resin is used. Is used.

Next, the operation of the conventional polymer electrolyte fuel cell will be described.

A hydrogen-containing gas obtained by reforming a hydrocarbon-based fuel, for example, is used as a fuel gas in a fuel cell stack 13 formed by stacking the unit cells 12 through a fuel gas flow groove 8 and a fuel electrode 4. When air is supplied to the oxidant electrode 7 through the oxidant gas flow groove 10 as an oxidant gas and an electric current is taken out from an external circuit, the both electrodes 4 and 7 have the following chemical reaction formula. A reaction occurs on the basis of this.

[0014]

[Chemical 1]

As described above, at the fuel electrode 4, hydrogen becomes protons (H ⁺ ), and moves along with water in the solid polymer electrolyte membrane 1 from the fuel electrode 4 side toward the oxidizer electrode 7 side to be oxidized. The agent electrode 7 reacts with oxygen to generate water. From this, in the polymer electrolyte fuel cell, the polymer electrolyte membrane 1
Is saturated with water, the specific resistance of the solid polymer electrolyte membrane 1 is reduced, and the solid polymer electrolyte membrane 1 functions as a proton conductive electrolyte. Then, in order to increase the starting power of the unit cell 12 and maintain high power generation efficiency, the reaction gas is humidified to increase the humidity and then supplied to the fuel cell, or liquid water is supplied together with the reaction gas. In addition, by evaporating water by the heat of reaction inside the battery, evaporation of water from the solid polymer electrolyte membrane 1 is suppressed and the membrane is prevented from drying.

On the other hand, in the oxidant catalyst layer 5 of the oxidant electrode 7, the water produced by the electrode reaction flows in the fuel gas flow groove 8 and the oxidant gas flow groove 10 together with the surplus reaction gas and flows into the battery. It is discharged to the outside. At that time, as shown in FIG. 15 (a), the amount of water contained in the oxidant gas is such that when the humidity of the oxidant gas is increased and supplied into the battery on the inlet side, the humidity on the outlet side becomes saturated vapor. The pressure is exceeded and supersaturation occurs, and water blocks the oxidizer electrode 7. As a result, the diffusion of gas into the oxidant catalyst layer 5 is hindered, the cell reaction is hindered,
This causes a decrease in electromotive force.

As a means for solving such a problem, FIG.
As shown in FIG. 6, the oxidant gas flow groove 10 formed in the oxidizer separator 11 and connecting the oxidant gas inlet portion 18 and the oxidant gas outlet portion 19 is formed in a meandering shape, and the oxidant gas flow groove is formed. It has been proposed to reduce the flow passage cross-sectional area of 10 and increase the flow rate of the oxidant gas to blow excess water generated in the battery to the outside (US Patent USP).
No. 4988583, US Pat. No. 5,810,885.
No. 49). Reference numeral 20 is a fuel gas inlet portion, and reference numeral 21 is a fuel gas outlet portion.

Further, as shown in FIG. 15B, when the oxidizing gas is supplied into the battery while keeping the humidity of the oxidizing gas low at the inlet, the oxidizing catalyst layer 5 near the inlet is dried. The specific surface area of the oxidant catalyst layer 5 that contributes to the battery reaction is reduced, and the electromotive force is reduced. Further, the solid polymer electrolyte membrane 1 near the inlet side also dries, the specific resistance of the solid polymer electrolyte membrane 1 becomes large, the function as a proton conductive electrolyte also deteriorates, and synergistically reducing the electromotive force. It has become.

The excess water shown in FIG.
As another means for solving the problem of insufficient water shown in (b), for example, as described in JP-A-2000-277130, the water content of the solid polymer electrolyte membrane 1 on the oxidant gas inlet side is described. A method of increasing the ratio of the gas permeability of the inlet side 6a of the oxidizing gas diffusion layer 6 as compared with the gas permeability of the outlet side 6b of the oxidizing gas diffusion layer 6 as shown in FIG. 17 (a). Method for reducing the size (Japanese Patent Laid-Open No. 11-15
4523) or as described in JP 2001-6698 A, the inlet side 6 of the oxidant gas diffusion layer 6
Method of mixing carbon particles into a (Japanese Patent Laid-Open No. 2001-67
No. 08) or a method of increasing the content of the water repellent from the outlet side to the inlet side of the oxidant gas diffusion layer (Japanese Patent Laid-Open No. 2001-2001).
No. 6708), for example, as shown in FIG. 17B, a method of increasing the thickness from the outlet side 6a of the oxidant gas diffusion layer 6 toward the inlet side 6b, or JP-A-2001-2001.
As described in Japanese Patent No. 135326, many proposals have been made such as interposing a mixed layer composed of a fluororesin and carbon black between the oxidant catalyst layer 5 and the oxidant gas diffusion layer 6. .

[0020]

In the conventional polymer electrolyte fuel cell, the excess water shown in FIG.
As described above, many solutions have been proposed for the problem of insufficient water shown in (b).

[0021] However, even if many solutions to these problems have been proposed, there is still some concern. That is, it is difficult for the solution shown in FIG. 16 against excess water to blow off the water overflowing the oxidant electrode 7 even if the oxidant gas flow groove 10 is formed in a meandering shape (US Pat. No. 4,9885).
83, U.S. Pat. No. 5,108,849). Further, if the oxidant gas flow groove 10 has a meandering shape, the length of the groove is long, resulting in a large pressure loss, and the oxidant gas must be pressurized in advance and supplied, resulting in power consumption. . Further, excessive heat is required to humidify the oxidant gas to a high humidity before supplying it to the battery, which causes a decrease in plant thermal efficiency.

Further, in the means for solving the problems of excess and insufficient water, the solution disclosed in Japanese Patent Laid-Open No. 2000-277130 has small proton migration in the solid polymer electrolyte membrane 1 having a low water content and is large in the battery. May induce current density distribution.

Further, Japanese Patent Laid-Open No. 11-154523,
JP-A-2001-6698, JP-A-2001-670
In Japanese Patent Laid-Open No. 8-58, the porosity, thickness, and water repellent content of the oxidant gas diffusion layer 6 have an in-plane distribution, and the gas permeability of the oxidant gas diffusion layer 6 is taken into consideration. Agent catalyst layer 5
The original function of the oxidant gas diffusion layer 6 such as diffusing the oxidant gas into the air and evaporating the generated water to discharge it into the oxidant gas flow groove 10 is impaired, leading to a decrease in the battery reaction efficiency. There is a risk.

Further, in Japanese Patent Laid-Open No. 2001-135326, the thickness of the mixed layer is changed between the inlet side and the outlet side by the partial pressure of water vapor, but even if water increases in proportion to the current density, The partial pressure difference of water vapor does not increase proportionally across the mixed layer, and it may not be possible to cope with load fluctuations.

The present invention has been made to solve the above problems, and the solid polymer electrolyte is directed from the inlet side to the outlet side of the oxidant gas without causing a large current density distribution in the cell surface. The membrane and the oxidant catalyst layer do not dry over time, and the water generated at the outlet side of the oxidant gas does not overflow and hinder the diffusion of the oxidant gas into the oxidant catalyst layer. It is an object of the present invention to provide a polymer electrolyte fuel cell for

[0026]

A polymer electrolyte fuel cell according to the present invention has the following object to attain the above objects.
As described above, of both sides of the solid polymer electrolyte membrane arranged in the central part, the fuel electrode is provided on one side and the oxidant electrode is provided on the other side, and the oxidant electrode is the solid polymer electrolyte. In a polymer electrolyte fuel cell in which an oxidant catalyst layer and an oxidant gas diffusion layer are arranged in this order from the membrane toward the oxidant separator on the outside, water is provided between the oxidant catalyst layer and the oxidant gas diffusion layer. It is provided with a porous layer for evaporation control.

Further, in order to achieve the above-mentioned object, the polymer electrolyte fuel cell according to the present invention has, as described in claim 3, the water vaporization controlling porous layer, in which the distribution of the material type and the average gas content are Select at least one of the pore size distribution and the thickness distribution along the flow direction of the oxidant gas, and select either one of the slope shape and the step shape from the inlet side toward the outlet side. It changes.

Further, in order to achieve the above-mentioned object, the polymer electrolyte fuel cell according to the present invention has, as described in claim 4, a water-repellent porous layer comprising a water-repellent material and a hydrophilic material. Of these, at least one is included,
Of the content and the specific surface area of the water repellent material, at least one is along the flow direction of the oxidant gas, and among the inclined shape and the step shape from the inlet side to the outlet side,
Either one is selected to be formed small, and at least one of the content rate and the specific surface area of the hydrophilic material is along the flow direction of the oxidant gas, and is inclined from its inlet side to its outlet side. One of the step shapes is selected to form a large size.

In the polymer electrolyte fuel cell according to the present invention, in order to achieve the above-mentioned object, as described in claim 2, the water evaporation controlling porous layer is an average of the oxidant gas diffusion layers. It is smaller than the pore size.

In the polymer electrolyte fuel cell according to the present invention, in order to achieve the above object, as described in claim 5, the water repellent material is a fluororesin, a carbon fluoride,
Of the carbon treated with carbon and water repellent,
It includes at least one kind.

In order to achieve the above-mentioned object, the polymer electrolyte fuel cell according to the present invention has a hydrophilic material which is an oxide or an inorganic powder whose surface is hydrophilically treated. Among the metal powders whose surfaces have been hydrophilically treated, at least one kind is contained.

In order to achieve the above-mentioned object, the polymer electrolyte fuel cell according to the present invention is characterized in that, as described in claim 7, the oxide is aluminum oxide, iron oxide, copper oxide, zirconium oxide. , At least one of titanium oxide, tin oxide, magnesium oxide, nickel oxide, manganese oxide, chromium oxide, and zinc oxide.

In order to achieve the above-mentioned object, the polymer electrolyte fuel cell according to the present invention is characterized in that the oxide contains an OH group, a SO ₃ H group or a COOH group. Of these, at least one type is included.

Further, in order to achieve the above-mentioned object, the polymer electrolyte fuel cell according to the present invention has, as described in claim 9, the water vaporization controlling porous layer having at least different surface tensions with respect to water. Including two kinds of materials,
A distribution of a material having a small surface tension with respect to water is along the flow direction of the oxidant gas, and either one of an inclined shape and a step shape from the inlet side to the outlet side is selected, and a large amount is contained, The distribution of the material having a large surface tension with respect to water is selected along the flow direction of the oxidant gas from the outlet side toward the inlet side, and either one of a slope shape and a step shape is selected and a large amount is contained. It is a thing.

Further, in the polymer electrolyte fuel cell according to the present invention, in order to achieve the above-mentioned object, as described in claim 10, the water evaporation controlling porous layer oxidizes the distribution of the average pore diameter. One of the inclined shape and the step shape is selected from the inlet side toward the outlet side along the flow direction of the agent gas, and is formed small.

Further, in the polymer electrolyte fuel cell according to the present invention, in order to achieve the above-mentioned object, as described in claim 11, the water evaporation controlling porous layer has a thickness distribution of oxidant gas. One of the inclined shape and the stepped shape is selected along the flow direction of (1) from the inlet side to the outlet side and is formed thick.

[0037]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of a polymer electrolyte fuel cell according to the present invention will be described with reference to the drawings and the reference numerals attached to the drawings.

FIG. 1 is a conceptual diagram showing a first embodiment of a polymer electrolyte fuel cell according to the present invention.

The solid polymer electrolyte fuel cell according to the present embodiment has a solid polymer electrolyte membrane 22 arranged at the center, and an oxidizer electrode 23 and an oxidizer electrode 23 on one side of both sides of the solid polymer electrolyte membrane 22. The oxidizer separator 24 having the agent gas passage groove 28 is arranged in layers, and the fuel electrode 25 and the fuel separator 26 are arranged in layers on the other side so that one unit cell (unit cell) 27 is formed. It has become. Since the fuel electrode 25 and the fuel separator 26 are not the targets of the polymer electrolyte fuel cell according to the present invention, the description thereof will be omitted here.

The oxidant electrode 23 is the solid polymer electrolyte membrane 2
From 2, the oxidant catalyst layer 29, the water evaporation control porous layer 30, and the oxidant gas diffusion layer 31 are arranged in layers in this order from the outer oxidant separator 24.

Further, the water evaporation controlling porous layer 30 is, for example, along the flow of the oxidant gas, for example, an inlet side water evaporation controlling porous layer 32, an intermediate water evaporation controlling porous layer 33, and an outlet side water evaporation controlling. Each of the porous layers 3 is divided into three parts, that is, the porous layers 34, so that the humidity is substantially evenly distributed along the flow direction of the oxidant gas in the solid polymer electrolyte membrane 22 and the oxidant catalyst layer 29.
At least one of the weight ratio of the water repellent material and the specific surface area of the water repellent materials 2, 33, 34 is changed in a stepwise manner.

The water-repellent material-containing weight ratio and specific surface area are controlled so as to decrease from the inlet side water evaporation controlling porous layer 32 toward the outlet side water evaporation controlling porous layer 34.

The inlet side water evaporation controlling porous layer 32 has at least one of the weight ratio and the specific surface area of the water repellent material increased for the following reason.

On the inflow side of the inlet side water evaporation control porous layer 32, the air used as the oxidant gas is in a relatively dry state. Therefore, water is in a state where it absorbs reaction heat and is easily evaporated.

The present embodiment focuses on such a point, and the inlet side water evaporation controlling porous layer 32 is originally intended to suppress the evaporation function of the water evaporation controlling porous layer 30. Therefore, a large amount of water-repellent material is contained, and the water generated in the oxidant catalyst layer 29 by the cell reaction and the water moving from the fuel catalyst layer to the oxidant catalyst layer 29 along with the proton (H ⁺ ) are the inlet side water. The evaporation is prevented from entering the pores of the evaporation controlling porous layer 32 to suppress the evaporation.

Further, the outlet side water evaporation controlling porous layer 34 is
The reason why at least one of the content weight ratio and the specific surface area of the water-repellent material is kept low is as follows.

On the discharge side of the outlet side water evaporation control porous layer 34, the air used as the oxidant gas is in a wet state. Therefore, the water is in a state of being hard to evaporate.

The present embodiment focuses on such a point, and the outlet side water evaporation controlling porous layer 34 is originally intended to promote the evaporation function of the water evaporation controlling porous layer 30. At least one of the weight ratio and the specific surface area of the water-repellent material is kept low, the hydrophilic material is contained, and the fuel is generated along with water and protons (H ⁺ ) generated in the oxidant catalyst layer 29 by the cell reaction. The water moving from the catalyst layer to the oxidant catalyst layer 29 is the outlet side water evaporation control porous layer 34.
It is designed to facilitate the infiltration into the pores and promote the evaporation.

The intermediate layer water evaporation controlling porous layer 33 is
At least one of the water-repellent material and the specific surface area having an intermediate content weight ratio between the inlet-side water evaporation control porous layer 32 and the outlet-side water evaporation control porous layer 34 and a hydrophilic material are contained.

FIG. 2 shows the porous layer 32 for controlling water vaporization on the inlet side.
Evaporation rate evaluation for investigating the evaporation rate of water when the content weight ratio of the water repellent material and the hydrophilic material contained in each of the intermediate layer water evaporation control porous layer 33 and the outlet side water evaporation control porous layer 34 is changed. It is a conceptual diagram which shows a test device.

This evaporation rate evaluation test device is equipped with a humidifier 35.
And an evaporation rate test device 36.

The humidifier 35 includes a water tank 37 filled with the humidifying water W1 with a dry nitrogen pipe 38, a humidified nitrogen pipe 39, and a humidifier water level gauge 40.
While being covered with 1, the heater 42 is attached to the heat insulating material 41.

Further, the evaporation rate test device 36 includes a simulated oxidant gas flow groove 44 and an oxidant gas diffusion layer 4 which are connected to the humidified nitrogen pipe 39 in the container 43 filled with the simulated water W2.
5. Test material 4 for the above-mentioned porous layers 32, 33, 34
6. Equipped with an evaporation evaluation water level gauge 47 and a container 43
The outside of the heater is covered with a heat insulating material 48, while the heat insulating material 48 and the test material 46 are provided with heaters 49a, 49a, 49, respectively.
Wearing b.

In carrying out the evaporation rate evaluation test of the test materials 46 having different content weight ratios of the water-repellent material and the hydrophilic material using the evaporation rate evaluation test apparatus having such a structure, first, the carbon paper made of carbon fiber is used. A water-repellent carbon is prepared for the oxidant gas diffusion layer 45 made of aluminum, and the weight content of the fluororesin is 10%, 20%, 30%.
%, 40% mixture of fluororesin and carbon powder,
A test material 46 is deposited on the above-described oxidant gas diffusion layer 45 prepared in advance.

As described above, the test material 46 is integrated with the oxidant gas diffusion layer 45, and the simulated water W is formed by using the four kinds of specimens.
Experimentally evaluate how fast 2 vaporizes.

At this time, the test material 46 is equipped with a heater 49b for simulating heat generation due to a battery reaction. The heater 49b is controlled so that the heat input is constant.
For example, when simulating a state where the current density is 0.2 A / cm ² , the heat generation is set to 1.7 cal / min / cm ² , and when the current density is 0.4 A / cm ² , the heat generation is 3.2 cal. It is controlled to be / min / cm ² .

Further, in the water tank 43, protons (H
⁺ ), Water W2 simulating both of the water moving from the fuel catalyst layer to the oxidant catalyst layer 29 is filled so as to contact the test material 46. This water W2 is added to the cell temperature, for example, 80
The temperature is controlled by the heaters 42, 42 mounted on the upper and lower sides of the water tank 37 so that the temperature can be maintained at ° C. The evaporation amount of the water W2 from the test material 46 is evaluated by the evaporation amount evaluation water level gauge 47 provided in the container 43.

On the other hand, the air evaporated from the test material 46 is
It is released to the atmosphere through a simulated oxidant gas flow groove 44 provided on the head side of the oxidant gas diffusion layer 45. Humidified nitrogen obtained by humidifying dry nitrogen obtained by vaporizing liquid nitrogen in the water tank 37 is supplied to the simulated oxidant gas flow groove 44.

In the water tank 37, after the humidifying water W1 is filled, the relative humidity of the inlet-side water evaporation control porous layer 32 of the test material 46 is, for example, 30%, and the intermediate water evaporation control porous layer 3 is 30%.
The relative humidity of No. 3 is 60%, and the relative humidity of the outlet-side water evaporation control porous layer 34 is controlled by the heater 42 so as to be 90%, for example. Then, the specific measurement is evaluated by the change in the water level read by the evaporation amount evaluation water level gauge 47 provided in the container 43 of the evaporation rate test device 36.

Normally, the polymer electrolyte fuel cell is operated at an oxidizer utilization rate in the range of 30 to 70%, but the humidity of the inlet side water evaporation control porous layer 32 and the middle part water evaporation control are controlled. Porous layer 34 for controlling humidity and outlet side water evaporation of porous layer 33
In the test simulating the humidity, the flow rate of the supplied nitrogen is increased, the entire surface of the test material 46 is made to have a substantially uniform temperature, and the supply amount of nitrogen is 10% corresponding to the oxidant gas utilization rate.

FIG. 3 is a water evaporation rate diagram of the test material 46 obtained by using the evaporation rate evaluation test apparatus shown in FIG. In the figure, the diagram in which the black dots are plotted is the test result.

In this case, the output of the heater 49b mounted on the test material 46 is set to 1.7 cal / min / cm ² and the current density is 0.2 A / cm ² .

The test result is the evaporation rate of water with respect to the relative humidity of humidified nitrogen when the weight percentage of the fluororesin in the test material 46 is set to 10%, 20%, 30% and 40%.

FIG. 3 shows the actual operating current density of 0.2.
Water generated by the electrode reaction of A / cm ² and water that moves from the fuel catalyst layer to the oxidant catalyst layer 29 along with protons (H ⁺ ) (generated water of 0.2 A / cm ² + transferred water)
The dashed line shows the guideline of the evaporation rate required for the total of Eq. Further, the inlet side water evaporation control porous layer (corresponding to the inlet portion) 32, the intermediate water evaporation control porous layer (corresponding to the central portion) 33, and the outlet side water evaporation controlling porous layer (corresponding to the outlet portion) 34 are relative to each other. Humidity is indicated by a chain line.

The point where the broken line and the alternate long and short dash line intersect is the inlet water evaporation control porous layer 32 of the water evaporation control porous layer 30.
The weight content of the fluororesin suitable for each of the intermediate layer water evaporation controlling porous layer 33 and the outlet side water evaporation controlling porous layer 34 is shown.

When the weight content of the fluororesin is read from FIG. 3, the inlet side water evaporation control porous layer 32, the intermediate part water evaporation control porous layer 33 and the outlet side water evaporation control porous layer 34.
, Respectively, are less than 37%, 19% and 10%, respectively.

As described above, in this embodiment, the weight content of the fluororesin as the water-repellent material contained in the inlet-side water evaporation control porous layer 32 is increased, and the intermediate water evaporation control porous layer 33 and the outlet are provided. Since the weight content of the fluororesin with respect to the side water evaporation control porous layer 34 is gradually decreased, the humidity of each of the oxidant catalyst layer 29 and the solid polymer electrolyte membrane 22 is adjusted along the flow direction of the oxidant gas. It can be made uniform.

However, in FIG. 3, since the weight content of the water repellent material of the test material 46 having the weight content of the fluororesin of 10% is kept low, the water W2 penetrates into the pores of the test material 46. It has become easier and the evaporation rate has increased accordingly. However, as seen in FIG. 3, the evaporation rate does not reach the intersection of the broken line indicating the required evaporation rate and the alternate long and short dash line indicating the relative humidity of the outlet-side water evaporation controlling porous layer (corresponding to the outlet) 34. That is, even if the test material 46 containing 90% of carbon material + 10% of fluororesin is used, the evaporation rate becomes slow when the relative humidity at the outlet of the oxidant is high.

Therefore, in the present embodiment, the test material 46
A hydrophilic material was contained in the sample to make it easier for the simulated water W2 to enter, and to accelerate the evaporation rate. As a hydrophilic material, an oxide is generally excellent, but here, zirconium oxide (hereinafter referred to as zirconia) was selected as an example of the oxide, and 5% and 10% by weight were contained. . Then, two kinds of test materials 46 of carbon material 85% + fluororesin 10% + zirconia 5% and test material 46 of carbon material 80% + fluororesin 10% + zirconia 10% were prepared in terms of weight ratio.

Further, in FIG. 3, the test results are plotted as white dots. From the diagram in which the white points are plotted, it was confirmed that the higher the content of zirconia, the higher the evaporation rate. Considering it in detail, if the content weight ratio of zirconia is set to about 8% between 5% and 10%, the relative humidity of the outlet side water evaporation control porous layer (corresponding to the outlet portion) is 90%. The alternate long and short dash line indicating% intersects with the broken line indicating the required evaporation rate. From this, it was found that the required evaporation rate can be secured by setting the zirconia-containing weight ratio to about 8%.

Therefore, in consideration of the diagram plotted as a black dot and the diagram plotted as a white dot, the material of the inlet side water evaporation controlling porous layer 32 is made of the carbon material 63%. + Fluorine resin 37%, the material of the intermediate part water evaporation control porous layer 33 is carbon material 81% + Fluorine resin 19%, and the material of the outlet side water evaporation control porous layer 34 is carbon material 82 % + Fluororesin 1
When the water vaporization controlling porous layer 30 is manufactured by combining the composition of 0% + zirconia 8%, the solid polymer electrolyte membrane 22 and the oxidant catalyst layer 29 are formed along the flow of the oxidant gas.
It was found that the humidity distribution can be made uniform.

FIG. 4 is a humidity distribution diagram in which the catalyst control porous layer 30 along the flow direction of the oxidizing gas corresponds to the distribution of the humidity in the oxidizing gas and the oxidizing catalyst layer.

FIG. 4 is a calculation result based on the data obtained in FIG. 3. According to the calculation result, although the humidity distribution in the oxidant catalyst layer 29 is sawtooth, it is high. Maintained in humidity.

Therefore, from FIG. 4, the oxidant catalyst layer 29
Since the inside is maintained at high humidity, it is possible to eliminate the phenomenon that water overflows into the oxidant catalyst layer 29 on the oxidant gas outlet side and closes the oxidant catalyst layer 29. Further, the solid polymer electrolyte membrane 2 is provided on the oxidant gas inlet side.
2 and the phenomenon that the oxidant catalyst layer 29 is dried are also eliminated.

As described above, in this embodiment, the water evaporation control porous layer 30 is interposed between the oxidant catalyst layer 29 and the oxidant gas diffusion layer 31, and the water evaporation control porous layer 30 is provided.
For example, the inlet side water evaporation control porous layer 32, the intermediate part water evaporation control porous layer 33, and the outlet side water evaporation control porous layer 3
Since the absorption of water is controlled by each of the porous layers 32, 33 and 34, the solid polymer electrolyte membrane 2
2. To reduce the specific resistance over the whole, to secure high pronto conductivity, to maintain a high oxidant catalyst function over the entire surface of the battery, and to maintain a high electromotive force for a single cell for a long time. You can

The water evaporation controlling porous layer 30 shown in FIG.
In the evaporation rate evaluation test, the current density was 0.2 A / cm ² and the output of the heater 49b was 1.7 cal / min / cm.
^It is fixed at ² .

However, there is a load fluctuation in the actual machine, and it is considered that the humidity distribution of the solid polymer electrolyte membrane 22 and the oxidant catalyst layer 29 fluctuates due to the load fluctuation.

In consideration of such a point, the present embodiment uses the evaporation rate test device 36 shown in FIG. 2 again and sets the current density to 0.2 A / cm ² , 0.4 A / cm ² and 0.6 A / cm ^2.
Considering A / cm ² , each simulated reaction heat was 1.7c
al / min / cm ² , 3.2 cal / min / cm ²
And an evaporation rate evaluation test when set to 4.7 cal / min / cm ² .

In this case, the test material 46 of the water evaporation control porous layer 30 is made of the material of the inlet side water evaporation control porous layer 32 of carbon material 63% + fluorine resin 37 based on the test result shown in FIG. %, The material of the intermediate water evaporation control porous layer 33 is 81% of carbon material + fluorine resin 19%, and the material of the outlet side water evaporation control porous layer 34 is 82% of carbon material + 10% fluorine resin + 8 zirconia %.

The relative temperature of humidified nitrogen was 30% for the test material 46 of the inlet side water evaporation control porous layer 32, 60% for the test material 46 of the intermediate water evaporation control porous layer 33, and at the outlet side. The test material 46 of the porous layer 34 for water evaporation control is 9
It was set to 0%. Further, the flow rate of the supplied nitrogen was set to 10%, which corresponds to the utilization rate of the oxidizing gas. Furthermore, the simulated water W2 filled in the container 43 shown in FIG. 2 was set to 80 ° C.

Under the above set conditions, the test data shown in FIG. 5 was obtained.

From FIG. 5, the test material 46 of each of the inlet side water evaporation controlling porous layer 32, the intermediate part water evaporation controlling porous layer 33, and the outlet side water evaporation controlling porous layer 34 is the evaporation rate and the simulated reaction. It was found that the heat was linear and the slope was almost the same.

In general, fuel cells have increased current density.
Then, the heat of reaction and water also increase proportionally. this
Water is water (produced water) or protons produced by the reaction.
(H ⁺) Included with water (mobile water)
It

In the present embodiment, attention is paid to this point, and the water evaporation control porous layer 30 is provided with a function of controlling the water evaporation rate. By controlling the water evaporation rate, the load is reduced. Regardless of the flow of the oxidant gas, the solid polymer electrolyte membrane 22 and the oxidant catalyst layer 2 are directed from the inlet side toward the outlet side.
The humidity distribution within 9 could be made uniform.

Next, a method for manufacturing an oxidizer electrode applied to the polymer electrolyte fuel cell according to the present invention will be described.

The oxidant electrode 23 is the solid polymer electrolyte membrane 2
2. The oxidant catalyst layer 29, the water evaporation control porous layer 30, the oxidant gas diffusion layer 31, and the oxidant separator 24 are combined, and among these, the oxidant electrode according to the present embodiment is used. As shown in FIG. 6, the manufacturing method is applied to the water evaporation control porous layer 30.

The water evaporation controlling porous layer 30 is divided into the inlet side water evaporation controlling porous layer 32, the intermediate part water evaporation controlling porous layer 33 and the outlet side water evaporation controlling porous layer 34 as described above. There is. Therefore, each porous layer 32, 33, 34
Are manufactured separately and then integrally molded.

First, in producing the inlet-side water evaporation control porous layer 32, as carbon powder having a weight content of 63%, for example, Farnest Black, manufactured by Cabot Corporation,
Trade names VALCAN, XC72 and water-repellent material having a weight content of 37%, for example, polytetrafluoroethylene, manufactured by DuPont, trade name Teflon (hereinafter referred to as PTFE) are suspended in water and mixed. This mixed liquid is an oxidant gas diffusion layer (for example, carbon paper, TGP manufactured by Toray).
H-120) 31 is coated on 1/3 of the entire area.

The oxidant gas diffusion layer 31 coated with the mixed solution is fired at 350 ° C. in an electric furnace.

Next, the intermediate water evaporation control porous layer 33 is
Carbon powder having a weight content of 81% and PTPF having a weight content of 19% were suspended in water in the oxidant gas diffusion layer 31 after firing, and this mixed liquid was
Coat 1/3 of the area and again 350 ° C in an electric furnace
Bake to.

Further, the outlet side water evaporation controlling porous layer 34
Is 82% by weight in the oxidant gas diffusion layer 31 after firing.
Of the carbon powder, PTFE having a weight content of 10% and zirconia having a weight ratio of 8% are suspended in water, and the mixed solution is coated on the remaining portion of the oxidant gas diffusion layer 31, and again at 350 ° C. in an electric furnace. Bake to.

As described above, one oxidant gas diffusion layer 31 is formed.
The inlet side water evaporation control porous layer 32, the intermediate part water evaporation control porous layer 33 and the outlet side water evaporation control porous layer 34 adhered to the rollers 50a,
Surface conditioning is performed at 50b.

In the present embodiment, zirconia was selected as the oxide having excellent hydrophilicity, but not limited to this example, aluminum oxide, iron oxide, copper oxide, lead oxide, titanium oxide, tin oxide, magnesium oxide may be used. , Nickel oxide, manganese oxide, chromium oxide, or zinc oxide may be selected, or a combination thereof may be selected.

Further, inorganic powder or metal powder whose surface is hydrophilically treated may be used. For example, in order to hydrophilically treat an inorganic powder such as zirconia, a powder having a particle size of about 0.1 μm is immersed in 1 mol of sulfuric acid for about 10 minutes, and then 800
It can be easily realized by heat treatment in an electric furnace of up to 1000 ° C.

Further, as the hydrophilic material, OH group, SO ₃
There are oxides having H groups and COOH groups. For example,
To have OH groups in the oxide, the particle size should be 0.1 to several μm.
It can be easily realized by immersing the powder of zirconia, tin oxide or titanium oxide in 5 mol. Of sodium hydroxide aqueous solution for about 10 minutes and then performing a heat treatment for about 20 minutes in an electric furnace at about 200 ° C. it can.

Further, in this embodiment, the oxidant gas diffusion layer 3 is used.
1, for example, the inlet side water evaporation control porous layer 32, the intermediate part water evaporation control porous layer 33, the outlet side water evaporation control porous layer 34.
In this case, at least one of the weight content ratio and the specific surface area of the water repellent material or the material having a large surface tension is made larger in the inlet side water evaporation controlling porous layer 32, and the intermediate part water evaporation is made. To the control porous layer 33 and the outlet-side water evaporation control porous layer 34, the amount of the hydrophilic material or the material having a small surface tension is gradually reduced in a stepwise manner along the flow of the oxidant gas. At least one of the rate and the specific surface area of the outlet side water evaporation control porous layer 3
4 to make it larger and to gradually reduce it by backflowing into the oxidizing gas flow stepwise toward the intermediate water evaporation control porous layer 33 and the inlet side water evaporation control porous layer 32, or the average pore diameter. At the inlet-side water evaporation control porous layer 32, and becomes gradually smaller along the oxidant gas flow stepwise toward the intermediate-portion water-evaporation-control porous layer 33 and the outlet-side water-evaporation control porous layer 34. By doing so, the evaporation amount of water from the water evaporation controlling porous layer 30 is made uniform over the entire area from the upstream side to the downstream side of the oxidizing gas, and the humidity distribution of the solid polymer electrolyte membrane 22 and the oxidizing catalyst layer 29 is distributed. Is being made uniform.

Further, in the present embodiment, for example, the inlet side water evaporation control porous layer 32, the intermediate water evaporation control porous layer 33,
The average pore diameter of the water evaporation controlling porous layer 30 formed by combining the outlet side water evaporation controlling porous layer 34 is made relatively smaller than the average pore diameter of the oxidant gas diffusion layer 31, and the capillary force is increased. Since the method is appropriately selected, the evaporation of water can be controlled accurately, and along with this, the humidity distribution in the solid polymer electrolyte membrane 22 and the oxidant gas diffusion layer 31 is saturated with the saturated vapor along the flow of the oxidant gas. The pressure is kept close to the pressure evenly.

FIG. 7 is a conceptual diagram showing a second embodiment of the polymer electrolyte fuel cell according to the present invention.

The solid polymer electrolyte fuel cell according to the present embodiment has the solid polymer electrolyte membrane 2 forming the oxidizer electrode 23.
2, the oxidant catalyst layer 29, the water evaporation control porous layer 30, the oxidant gas diffusion layer 31, the oxidant gas circulation groove 28 of the oxidizer separator 24, the water evaporation control porous layer 30,
Along the oxidant gas flow direction, and in order from the inlet side to the outlet side thereof, for example, the inlet side water evaporation control porous layer 32, the intermediate water evaporation control porous layer 33, the outlet side water evaporation control porous layer The oxidant gas diffusion layer 31 is divided into three layers such as the layer 34 and the like, and the oxidant gas diffusion layer 31 corresponds to the inlet side oxidant gas diffusion layer 51, the intermediate oxidant gas diffusion layer 52, and the outlet side oxidant gas diffusion layer 53. It is divided into.

Further, the polymer electrolyte fuel cell according to the present embodiment is divided into the inlet side water evaporation controlling porous layer 32, the intermediate part water evaporation controlling porous layer 33 and the outlet side water evaporation controlling porous layer 34. Among them, the thickness of the inlet-side water evaporation control porous layer 32 is reduced, and the thickness of the middle-portion water-evaporation control porous layer 33 and the outlet-side water evaporation control porous layer 34 is set to the thickness of the inlet-side water evaporation control porous layer 32. The thickness of the inlet-side oxidant gas diffusion layer 51 is increased accordingly, and the thickness of the middle-side oxidant gas diffusion layer 52 and the outlet-side oxidant gas diffusion layer 53 is increased by a step. In this embodiment, the total thickness of the water evaporation control porous layer 30 and the oxidant gas diffusion layer 31 is made constant along the oxidant gas flow direction.

As described above, in this embodiment, the thickness of the inlet side water evaporation controlling porous layer 32 is reduced, the heat transfer area is reduced to suppress the water evaporation rate, and the middle part water evaporation controlling porous layer 32 is formed. The thickness of the layer 33 and the outlet-side water evaporation control porous layer 34 is made relatively thicker than the thickness of the inlet-side water evaporation control porous layer 32 in order to increase the heat transfer area of each porous layer 33, 34. Since the evaporation rate of water is gradually increased to make the evaporation rate of water uniform even if there is a humidity distribution of the oxidant gas, the solid polymer electrolyte membrane 22 and the oxidizer are spread over the entire area from the inlet side to the outlet side of the oxidant gas. It is possible to make the humidity distribution in the catalyst layer 29 uniform.

FIG. 8 is a conceptual diagram showing a third embodiment of the polymer electrolyte fuel cell according to the present invention.

The solid polymer electrolyte fuel cell according to the present embodiment has the solid polymer electrolyte membrane 2 which constitutes the oxidant electrode 23.
2, the oxidant catalyst layer 29, the water evaporation control porous layer 30, the oxidant diffusion layer 31, and the oxidant gas passage groove 28, of the oxidizer separator 24, the water evaporation control porous layer 30, the oxidant gas flow. Along the direction, and in order from the inlet side to the outlet side, in the same manner as described above, the weight content or specific surface area of the water repellent material, the weight content or specific surface area of the hydrophilic material, the average porosity and the thickness. The inlet side water evaporation control porous layer 32, the middle part water evaporation control porous layer 33, and the outlet side water evaporation control porous layer 34, which are different from each other stepwise.
The oxidant gas passage groove 28, which connects the oxidant gas supply port 54 and the oxidant gas discharge port 55 of the oxidant separator 24 to each other, is meandered in the transverse direction of the oxidant separator 24. It is formed into a shape.

As described above, in the present embodiment, three inlet side water evaporation control porous layers 32, intermediate water evaporation control porous layers 33, and outlet side water evaporation control are provided, each having a different weight content of the water repellent material. Evaporation control porous layer 3 including a porous layer 34 for water
0 and a meandering oxidant gas flow groove 28 are combined to increase the relative humidity as a whole, as shown in FIG. 4, so that the oxidant gas flows along the flow of the oxidant gas. The humidity distribution in the solid polymer electrolyte membrane 22 and the oxidant catalyst layer 29 can be made substantially uniform over the entire area from the inlet side to the outlet side.

In this embodiment, the oxidizing gas flow groove 2 is used.
Although a plurality of 8 are simultaneously formed in a meandering shape, the present invention is not limited to this example. For example, as shown in FIG. 9 of the fourth embodiment, each oxidant gas flow groove 28 is formed in a meandering shape. Further, for example, as shown in FIG. 10 of the fifth embodiment, the oxidant gas passage groove 28 and the first oxidant gas passage groove 56 connecting the oxidant gas passage groove 28 to the oxidant gas supply port 54 may be formed. It is divided into a second oxidant gas passage groove 57 connected to the gas outlet 55, and the first and second oxidant gas passage grooves 56, 57 are interrupted in the middle of the oxidant separator 24, and during this time, oxidant gas diffusion Using the surface of the layer 31, the first oxidant gas flow groove 5
The oxidant gas may be caused to flow from 6 to the second oxidant gas flow groove 57. Further, the water evaporation control porous layer 30 shown in each of FIGS. 9 and 10 is divided into sections, for example, an inlet side water evaporation control porous layer 32, an intermediate water evaporation control porous layer 33 and an outlet side water evaporation control porous layer. Similarly to the above, the layer 34 is formed by stepwise varying the weight content of the water repellent material, the weight content of the hydrophilic material, the average porosity, and the thickness.

In addition, in the first embodiment shown in FIG. 1, the second embodiment shown in FIG. 7, the third embodiment shown in FIG. 8, the fourth embodiment shown in FIG. 9 and the fifth embodiment shown in FIG. In the above description, the case where the porous layer for controlling water evaporation is divided into 30 steps is described as an example.

However, if the number of such steps is two or more, it has the effect of making the humidity distribution in the solid polymer electrolyte membrane 22 and the oxidant catalyst layer 29 uniform. As the number of steps increases, the number of saw teeth shown in FIG. 4 increases, and the humidity distribution in the solid polymer electrolyte membrane 22 and the oxidant catalyst layer 29 becomes more uniform.

FIG. 11 shows a sixth embodiment of the polymer electrolyte fuel cell according to the present invention, in which the oxidizing gas and the oxidizing catalyst layer are formed in the water evaporation controlling porous layer along the flowing direction of the oxidizing gas. It is a humidity distribution line diagram corresponding to the distribution of the humidity of.

The solid polymer electrolyte fuel cell according to the present embodiment has the solid polymer electrolyte membrane 2 which constitutes the oxidant electrode 23.
2, among the oxidizer separator 24 including the oxidant catalyst layer 29, the water evaporation control porous layer 30, and the oxidant gas flow groove 28, the water evaporation control porous layer 30 is arranged along the oxidant gas flow direction, and From the entrance side to the exit side,
For example, the inlet side water evaporation control porous layer 32, the intermediate part water evaporation control porous layers 58 and 59, the outlet side water evaporation control porous layer 3
4. At least one of the weight content or specific surface area of the water repellent material, the weight content or specific surface area of the hydrophilic material, the material surface tension or the average porosity, or the thickness is continuously and gradually different. Is forming. Here, the inclined shape includes a linear inclination, a general inclination, a curvilinear inclination, and the like with respect to the thickness direction.

As described above, according to the present embodiment, the material, the average porosity, or the thickness of the water evaporation controlling porous layer 30 is continuously and obliquely varied, so that the oxidizer gas is changed as shown in FIG. The humidity distribution in the oxidant catalyst layer 29 can be maintained uniform with respect to the oxidant gas humidity distribution in which the oxidant gas humidity distribution rises from the inlet side toward the outlet side along the flow direction of.

Therefore, according to the present embodiment, the humidity distribution in the oxidant catalyst layer 29 is kept uniform along the flow of the oxidant gas and from its inlet side to its outlet side. The specific resistance is reduced over the entire solid polymer electrolyte membrane 22, a high pronto conductivity is ensured, a high oxidant catalytic function is maintained over the entire surface of the battery, and the cell is highly activated for a long time. Can be maintained at power.

[0112]

As described above, the solid polymer electrolyte fuel cell according to the present invention includes the oxidant electrode among the fuel electrode and the oxidant electrode provided on both sides of the solid polymer electrolyte membrane located in the central portion. Is composed of an oxidizer catalyst layer, a water evaporation control porous layer, an oxidizer gas diffusion layer, and an oxidizer separator provided with an oxidizer gas passage groove, which are sequentially arranged from the solid polymer electrolyte membrane toward the outside. The control porous layer, for example,
Of the multiple layer parts such as the inlet side water evaporation control porous layer, the intermediate part water evaporation control porous layer, and the outlet side water evaporation control porous layer, some are combined and divided into a plurality, and the water repellency of each porous layer At least one of the distributions of material content, hydrophilic material content, average porosity, thickness, etc. is selected to be different along the flow direction of the oxidant gas and from the inlet side to the outlet side. The oxidant gas diffusion layer is coated with each of the solutions of each porous layer, baked, and integrally molded to produce each porous layer. It can be surely adhered to the agent gas diffusion layer, and the humidity distribution in the solid polymer electrolyte membrane and the oxidant catalyst layer can be kept high and uniform along the flow direction of the oxidant gas.

Therefore, according to the polymer electrolyte fuel cell of the present invention, along the flow direction of the oxidant gas, and
Since the humidity distribution in the solid polymer electrolyte membrane and the oxidizer catalyst layer is kept high and uniform from the inlet side to the outlet side, the specific resistance of the solid polymer electrolyte membrane is reduced and the high Proton conductivity can be ensured, the oxidant catalyst function can be sufficiently exerted, the unit cell can be maintained at a high electromotive force for a long time, and the power generation efficiency can be further enhanced.

[Brief description of drawings]

FIG. 1 is a conceptual diagram showing a first embodiment of a polymer electrolyte fuel cell according to the present invention.

FIG. 2 is a conceptual diagram of an evaporation rate evaluation test device for testing a test material for a water evaporation control porous layer applied to the polymer electrolyte fuel cell according to the present invention.

FIG. 3 is a water evaporation rate diagram of a test material obtained by using the evaporation rate evaluation test apparatus shown in FIG.

FIG. 4 is a diagram showing a water vaporization control porous layer applied to the polymer electrolyte fuel cell according to the present invention, wherein the water vaporization control porous layer along the oxidant gas flow direction and the humidity in the oxidant gas and the oxidant catalyst layer. Of humidity distribution that correspond to the distribution of.

FIG. 5 is a diagram showing a relationship between an evaporation rate and a simulated reaction heat obtained by an experiment of a test material of a water evaporation controlling porous layer applied to the polymer electrolyte fuel cell according to the present invention.

FIG. 6 is a conceptual diagram used for explaining a method of manufacturing an oxidizer electrode applied to a polymer electrolyte fuel cell according to the present invention.

FIG. 7 is a conceptual diagram showing a second embodiment of the polymer electrolyte fuel cell according to the present invention.

FIG. 8 is a conceptual diagram showing a third embodiment of the polymer electrolyte fuel cell according to the present invention.

FIG. 9 is a conceptual diagram showing a fourth embodiment of the polymer electrolyte fuel cell according to the present invention.

FIG. 10 is a conceptual diagram showing a fifth embodiment of the polymer electrolyte fuel cell according to the present invention.

FIG. 11 shows a sixth embodiment of the polymer electrolyte fuel cell according to the present invention, in which the water evaporation controlling porous layer and the oxidant gas and the oxidant catalyst layer are formed along the oxidant gas flow direction. Humidity distribution diagram with corresponding humidity distribution.

FIG. 12 is a conceptual diagram showing a unit cell in a conventional polymer electrolyte fuel cell.

FIG. 13 is a conceptual diagram showing a fuel cell stack in a conventional polymer electrolyte fuel cell.

FIG. 14 is a conceptual diagram showing a unit cell in a conventional polymer electrolyte fuel cell.

FIG. 15 is a humidity distribution diagram showing the humidity of an oxidant gas in a conventional polymer electrolyte fuel cell, (a) shows the case where the humidity is excessive at the oxidant gas outlet, and (b) shows the oxidant. A diagram showing a case where the gas inlet is insufficient.

FIG. 16 is a conceptual plan view showing an oxidant gas separator in a conventional polymer electrolyte fuel cell.

FIG. 17 is a conceptual diagram showing an example of adjusting the gas permeability of an inlet of an oxidant gas diffusion layer in a conventional polymer electrolyte fuel cell, and (a) is a concept showing an example of reducing the gas permeability of the inlet. FIG. 1B is a conceptual diagram showing an example in which the thickness of the oxidant gas diffusion layer is gradually reduced from the inlet to the outlet so that the gas permeability has a distribution.

[Explanation of symbols]

1 Solid polymer electrolyte membrane 2 Fuel catalyst layer 3 Fuel gas diffusion layer 4 Fuel electrode 5 Oxidizing agent catalyst layer 6 Oxidant gas diffusion layer 6a entrance side 6b Exit side 7 Oxidizer electrode 8 Fuel gas distribution groove 9 Fuel separator 10 Oxidant gas distribution groove 11 Oxidizer separator 12 cells 13 Fuel cell stack 14 Coolant distribution groove 15 Cooling plate 16 Fuel gas porous layer 17 Oxidant gas porous layer 18 Oxidant gas inlet 19 Oxidant gas outlet 20 Fuel gas inlet 21 Fuel gas outlet 22 Solid polymer electrolyte membrane 23 Oxidizer electrode 24 Oxidizer separator 25 Fuel electrode 26 Fuel separator 27 cells 28 Oxidant gas distribution groove 29 Oxidizing agent catalyst layer 30 Water evaporation control porous layer 31 Oxidant gas diffusion layer 32 Inlet-side water evaporation control porous layer 33 Middle part water evaporation control porous layer 34 Outlet side water evaporation control porous layer 35 Humidifier 36 Evaporation rate tester 37 aquarium 38 Dry nitrogen piping 39 Humidification nitrogen piping 40 Humidifier water level meter 41 Heat insulation material 42 heater 43 containers 44 Simulated oxidant gas distribution groove 45 Oxidant gas diffusion layer 46 Test material 47 Evaporation evaluation water level gauge 48 Thermal insulation 49a, 49b heater 50a, 50b rollers 51 Inlet side oxidant gas diffusion layer 52 Intermediate part oxidant gas diffusion layer 53 Outlet side oxidant gas diffusion layer 54 Oxidant gas supply port 55 Oxidant gas outlet 56 First oxidant gas flow groove 57 Second Oxidant Gas Flow Groove 58,59 Middle part water evaporation control porous layer

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H01M 8/10 H01M 8/10 F term (reference) 5H018 AA06 AS03 BB01 BB05 BB08 BB12 EE02 EE08 EE11 EE12 EE19 5H026 AA06 CC03 CX05 EE02 EE05 EE11 EE12 EE19 5H027 AA06

Claims (11)

[Claims] 1. A fuel electrode is provided on one side and an oxidant electrode is provided on the other side of both sides of the solid polymer electrolyte membrane arranged in the central portion, and the oxidant electrode is the solid polymer electrolyte membrane. In the solid polymer fuel cell in which the oxidant catalyst layer and the oxidant gas diffusion layer are arranged in this order from the oxidant catalyst layer to the outer oxidant separator, water evaporation is caused between the oxidant catalyst layer and the oxidant gas diffusion layer. A polymer electrolyte fuel cell comprising a control porous layer. 2. The polymer electrolyte fuel cell according to claim 1, wherein the water evaporation controlling porous layer is made smaller than the average pore diameter of the oxidant gas diffusion layer. 3. The water evaporation control porous layer comprises at least one selected from a material type distribution, an average pore size distribution and a thickness distribution along the flow direction of the oxidant gas and from the inlet side thereof. The polymer electrolyte fuel cell according to claim 1 or 2, wherein one of an inclined shape and a step shape is selected and changed toward the outlet side. 4. The water evaporation control porous layer contains at least one of a water repellent material and a hydrophilic material, and in the content ratio and the specific surface area of the water repellent material,
At least one is along the flow direction of the oxidant gas, and one of the inclined shape and the step shape from the inlet side toward the outlet side is selected to form a small size, and the content and ratio of the hydrophilic material are set. At least one of the surface areas is formed along the flow direction of the oxidant gas, and one of an inclined shape and a step shape from the inlet side to the outlet side is selected to be formed large. The polymer electrolyte fuel cell according to claim 1. 5. The solid height according to claim 4, wherein the water repellent material contains at least one kind of fluororesin, carbon fluoride, carbon and carbon treated with a water repellent agent. Molecular fuel cell. 6. The solid according to claim 4, wherein the hydrophilic material contains at least one kind of oxide, an inorganic powder whose surface is hydrophilically treated, and a metal powder whose surface is hydrophilically treated. Polymer fuel cell. 7. The oxide is aluminum oxide, iron oxide,
7. The solid polymer according to claim 6, containing at least one or more of copper oxide, zirconium oxide, titanium oxide, tin oxide, magnesium oxide, nickel oxide, manganese oxide, chromium oxide, and zinc oxide. Type fuel cell. 8. The oxide is an OH group, SO ₃ H group or COO.
7. The polymer electrolyte fuel cell according to claim 6, wherein at least one kind of H group is contained. 9. The porous layer for controlling water evaporation contains at least two kinds of materials having different surface tensions with respect to water, and distributes the material having a small surface tension with respect to water along the flow direction of the oxidant gas. One of a sloped shape and a stepped shape is selected from the inlet side toward the outlet side, and one of them is contained in a large amount, and the distribution of the material having a large surface tension with respect to water is along the flow direction of the oxidant gas, and 3. The polymer electrolyte fuel cell according to claim 1 or 2, wherein one of an inclined shape and a step shape is selected from the outlet side toward the inlet side, and a large amount is contained. 10. The water evaporation control porous layer has a distribution of average pore diameters along the flow direction of the oxidant gas, and from the inlet side to the outlet side thereof, a sloped shape and a stepped shape,
The polymer electrolyte fuel cell according to claim 3, wherein either one of them is selected and formed into a small size. 11. The water vaporization control porous layer has a thickness distribution along the flow direction of the oxidant gas, and is selected from one of an inclined shape and a step shape from the inlet side to the outlet side. The polymer electrolyte fuel cell according to claim 3, wherein the polymer electrolyte fuel cell is formed to be thick and thick.