JPH08190918A - Fuel cell - Google Patents

Abstract

PURPOSE: To provide a fuel cell capable of preventing overflow of an electrolyte to a fuel side passage and drop in gas diffusion in a fuel side porous part, and storing the amount of the electrolyte sufficient to ensure the long life. CONSTITUTION: A plurality of unit cells each having a fuel electrode 2 and an oxidizing agent electrode 3 faced through an electrolyte matrix 1 are stacked through a gas separating plate 12 constituted with porous parts 13, 14 comprising a dense layer 12, ribs 13b, 14b having gas passages for perpendicularly passing a fuel gas and an oxidizing agent gas formed on both sides of the dense layer 12, and webs 13a, 14a to form a fuel cell. The volume occupied by pores of the fuel side porous part 13 forming the fuel gas passage is made larger than the volume occupied by pores of the oxidizing agent side porous part 14 forming the oxidizing agent gas passage.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel cell, and more particularly to a gas separation plate for a phosphoric acid fuel cell.

[0002]

2. Description of the Related Art FIG. 5 is a perspective view showing an essential part of a conventional phosphoric acid fuel cell disclosed in, for example, Japanese Patent Laid-Open No. 1-95468. In the figure, 1 is an electrolyte matrix, 2 is an electrode catalyst layer forming a fuel electrode, 3 is an electrode catalyst layer forming an oxidant electrode, 4 and 5 are gas flow paths of fuel and oxidant gas which are orthogonal to each other, and 6 is gas separation. The plate is integrally configured by the dense layer 7, and the fuel-side porous portion 8 and the oxidant-side porous portion 9 formed on both surfaces thereof in a rib shape. The cross-sectional structure of the gas separation plate 6 is as shown in the cross-sectional view taken along line VI-VI in FIG. 5 shown in FIG. 6, and the porous portions 8 and 9 on both sides of the dense layer 7 are formed.
For example, a material having a large number of carbonaceous pores forms the gas flow paths 4 and 5 by the web 10 and the rib 11, respectively.

Next, the operation will be described. Gas separation plate 6
The fuel and the oxidant gas are supplied to the gas flow paths 4 and 5 formed by the fuel-side porous portion 8 and the oxidant-side porous portion 9 which are orthogonal to each other. At this time, the dense layer 7 of the gas separation plate 6 prevents the fuel and the oxidant flowing on both sides from mixing with each other. Both supplied gases are the electrode catalyst layers 2, 3
When the gas reaches the catalyst layer and reaches the catalyst layer, the gas is ionized and reacted through the electrolyte matrix 1 to generate power. Here, the unreacted gas and the water vapor which is a reaction product are the gas flow paths 4, 5
Is discharged to the outside through. Since the exhaust gas contains the vapor of phosphoric acid, which is an electrolyte, the electrolyte in the electrolyte matrix 1 and the electrode catalyst layers 2 and 3 becomes insufficient in the case of long-term operation. Both of the porous portions 8 and 9 of the gas separation plate 6 have a function of storing the electrolyte in the pores and supplying the electrolyte to the lacking portion of the electrolyte matrix or the electrode catalyst layer.

[0004]

Since the conventional phosphoric acid fuel cell is constructed as described above, the cell life is greatly extended by the electrolyte stored in the porous portions 8 and 9. However, depending on the operating conditions of the fuel cell (for example, high current density), the phosphate ion as the electrolyte is carried by the current through the matrix in the direction from the oxidant electrode to the fuel electrode, so that the electrolyte of the oxidant side porous portion 9 is removed. The phenomenon of moving to the fuel side porous portion 8 occurs. Therefore, the electrolyte overflows into the fuel-side flow path 4 and the gas diffusivity in the fuel-side porous portion 8 is significantly reduced to deteriorate the characteristics, so that a sufficient amount of electrolyte is stored to secure a long life. There was a problem that it could not be done.

The present invention has been made in order to solve the above-mentioned problems, and it is possible to prevent the electrolyte from overflowing into the fuel side flow passage and the deterioration of the gas diffusivity in the fuel side porous portion, and to prevent a long-term problem. It is an object of the present invention to obtain a fuel cell capable of storing a sufficient amount of electrolyte to ensure the life of the fuel cell.

[0006]

A fuel cell according to claim 1 of the present invention comprises a unit cell having a fuel electrode and an oxidant electrode facing each other with an electrolyte matrix in between, a dense layer and a fuel gas on both surfaces thereof, respectively. In a fuel cell in which a plurality of gas separators are formed with a gas separating plate composed of ribs forming a flow path that allows oxidant gas to flow in a direction orthogonal to each other and a porous portion made of a web, a fuel-side porosity forming a flow path of fuel gas is formed. The volume occupied by the pores of the portion is larger than the volume occupied by the pores of the oxidant-side porous portion forming the flow path of the oxidant gas.

A fuel cell according to a second aspect of the present invention is the fuel cell according to the first aspect, wherein the thickness of the web on the fuel side porous portion is larger than the thickness of the oxidant side web.

According to a third aspect of the present invention, in the fuel cell according to the first aspect, the width of the rib of the fuel side porous portion is larger than the width of the rib of the oxidant side porous portion.

According to a fourth aspect of the present invention, in the fuel cell according to the first aspect, the porosity of the fuel side porous portion is larger than that of the oxidant side porous portion.

Further, in the fuel cell according to the present invention, the pore diameter of the fuel-side porous portion forming the fuel gas passage is larger than the pore diameter of the oxidant-side porous portion forming the oxidant gas passage. It was done.

Further, in the fuel cell according to the sixth aspect, the average pore diameters of the fuel-side porous portion forming the fuel gas passage and the oxidant-side porous portion forming the oxidant gas passage are substantially equal to each other, and The pore size distribution of the side porous portion is broadened.

Further, in the fuel cell according to the seventh aspect, the average pore diameters of the fuel side porous portion forming the fuel gas flow passage and the oxidant side porous portion forming the oxidant gas flow passage are substantially equal to each other. The pore size distribution of the oxidant side porous portion is broadened.

Further, in the fuel cell according to the eighth aspect, the average pore diameters of the fuel side porous portion forming the fuel gas flow passage and the oxidant side porous portion forming the oxidant gas flow passage are substantially equal to each other. The pore size distribution of the porous parts on both sides is broadened.

A fuel cell according to a ninth aspect of the present invention is the fuel cell according to any one of the first to eighth aspects, wherein the amount of phosphoric acid stored in the fuel-side porous portion and the oxidant-side porous portion is 40 of both the porous portions. .About.60%.

[0015]

In the fuel cell according to the first aspect of the present invention, the pore volume of the fuel-side porous portion is made larger than that of the oxidant-side porous portion, so that the electrolyte in the oxidant-side porous portion has the fuel-side porous portion. Since the phosphoric acid fill level of the fuel-side porous portion does not increase above a certain level even if the fuel-side porous portion is moved to the above portion, it is possible to prevent the electrolyte from overflowing into the fuel-side flow passage and the deterioration of the gas diffusibility in the fuel-side porous portion.

In the fuel cell according to the present invention, the thickness of the web of the fuel side porous portion is made larger than that of the oxidant side porous portion, so that the pore volume of the fuel side porous portion is increased to the oxidant side. It can be made larger than the pore volume of the porous portion.

Further, in the fuel cell according to the present invention, the width of the rib of the fuel side porous portion is made larger than the width of the rib of the oxidant side porous portion, so that the pore volume of the fuel side porous portion is increased to the oxidant side. It can be made larger than the pore volume of the porous portion.

In the fuel cell according to the present invention, the porosity of the fuel-side porous portion is made larger than the porosity of the oxidant-side porous portion so that the pore volume of the fuel-side porous portion is smaller than that of the oxidant-side porous portion. It can be larger than the pore volume.

Further, in the fuel cell according to the present invention, the pore size of the fuel side porous portion is made larger than the pore size of the oxidant side porous portion, so that the electrolyte moves from the oxidant side porous portion to the fuel side porous portion. It is possible to prevent the electrolyte from overflowing into the fuel side flow path and to prevent the gas diffusivity from decreasing in the fuel side porous portion.

In the fuel cell according to the sixth aspect, the average pore diameters of the fuel-side porous portion and the oxidant-side porous portion are made substantially equal and the pore diameter distribution of the fuel-side porous portion is broadened so that the fuel-side porous portion is When the phosphoric acid fill level of the portion becomes high, the electrolyte can be pulled back toward the oxidant side porous part by the capillary suction force caused by the difference in the phosphoric acid fill level between the fuel side porous part and the oxidant side porous part, It is possible to prevent the electrolyte from overflowing into the fuel-side flow path and the decrease in gas diffusivity in the fuel-side porous portion.

Further, in the fuel cell according to the present invention, the average pore diameters of the fuel-side porous portion and the oxidant-side porous portion are made substantially equal to each other, and the pore diameter distribution of the oxidant-side porous portion is broadened, so that the oxidation is performed. When the phosphoric acid fill level in the agent-side porous part becomes low, the electrolyte is pulled back toward the oxidant-side porous part by the capillary suction force caused by the difference in the phosphoric acid fill level between the fuel-side porous part and the oxidant-side porous part. Therefore, it is possible to prevent the electrolyte from overflowing into the fuel-side flow path and the decrease in gas diffusivity in the fuel-side porous portion.

Further, in the fuel cell according to the present invention, the average pore diameters of the fuel-side porous portion and the oxidant-side porous portion are made substantially equal to each other, and the pore diameter distributions of both porous portions are broadened, so that the fuel-side porous portion is formed. When the phosphoric acid fill level of the oxidizer side becomes high or the phosphoric acid fill level of the oxidizer side porous part becomes low, the capillary suction force caused by the difference in the phosphoric acid fill level between the fuel side porous part and the oxidizer side porous part The electrolyte can be pulled back toward the oxidant-side porous portion, and the electrolyte can be prevented from overflowing into the fuel-side flow passage and the gas diffusivity in the fuel-side porous portion can be prevented from decreasing.

Further, in the fuel cell according to the ninth aspect, the storage amount of phosphoric acid in the fuel-side porous portion and the oxidant-side porous portion is set to 40% to 60% of the pore volume of both porous portions. It is possible to secure a long service life without overflow of the electrolyte into the flow path and deterioration of gas diffusivity in the fuel side porous portion.

[0024]

【Example】

Example 1. Embodiment 1 of the present invention will be described below with reference to the drawings. 1 is a perspective view showing a main part of a fuel cell according to Embodiment 1 of the present invention, and FIG. 2 is a line II in FIG.
A sectional view taken along the line A-IIA is shown in FIG.
It is a sectional view along IB-IIB. In the figure, 1 to 5 and 7 are the same as the conventional one, and the description thereof is omitted. Reference numeral 12 denotes a gas separation plate, and the dense layer 7 and the fuel-side porous portion 13 and the oxidant-side porous portion 14 which are formed in a rib shape on both surfaces thereof.
Are integrally configured by. Here, the fuel side porous portion 1
3, the thickness S ₁ of the web 13a is 0.9 mm, and the thickness S ₂ of the web 14a of the oxidant side porous portion 14 is 0.6 mm.
It is made thicker to increase the total volume, increase the pores, and increase the pore volume. Note that l ₁ and l ₂ are the same as 1.5 mm.

Next, the operation will be described. Since the operation under the normal condition is the same as the conventional one, the description thereof will be omitted, and the behavior when operating under the high current density condition will be described. When the electrolyte is phosphoric acid, since the transport number of hydrogen ions is 0.90 to 0.95, most of the electric current in the electrolyte is carried by hydrogen ions, but 5-10% is carried by phosphate ions. . Since the direction of the electric current in the electrolyte is from the fuel electrode to the oxidant electrode, the phosphate ions are carried from the oxidant electrode to the fuel electrode. The phosphate ions thus transferred become phosphoric acid and are accumulated in the fuel-side porous portion 13, so that the fill level (occupied ratio) becomes high. When the current density is small, the amount of transfer of the phosphoric acid amount is also small, and the level difference is caused by the return from the fuel side to the oxidant side, which is driven by the difference in phosphoric acid concentration between the fuel side and the oxidant side. It does not cause a big problem in performance. However, when operating at a high current density, the amount of phosphoric acid carried by the current becomes overwhelmingly larger than the amount of return due to the temperature difference, so the amount of phosphoric acid in the fuel side porous portion 13 increases. . In this structure, the thickness of the web 13a of the fuel-side porous portion 13 is 1.5 times the thickness of the web 14a of the oxidant-side porous portion 14, and the pore volume of the fuel-side porous portion 13 is large. Since the phosphoric acid fill level of the portion 13 does not increase above a certain level, it is possible to prevent the electrolyte from overflowing into the fuel side passage and the gas diffusivity from being significantly reduced.

Example 2. The web thickness S ₁ and S ₂ of the fuel-side porous portion 13 and the oxidant-side porous portion 14 are the same as 0.6 mm, and the width l ₁ of the rib 13b of the fuel-side porous portion 13 is 2.0.
mm, the width l ₂ of the rib 14b of the oxidant side porous portion 14 is 1.
The configuration was the same as in Example 1 except that the thickness was 5 mm.

With this configuration, when operating under high current density conditions, the width of the rib 13b of the fuel side porous portion 13 is set to about 1.3 times the width of the rib 14b of the oxidant side porous portion 14, so that the fuel side porous portion is formed. Since the pore volume of 13 is large,
In the same manner as above, it is possible to prevent the overflow of phosphoric acid into the flow path and the decrease in gas diffusivity.

Example 3. The web thicknesses S ₁ and S _{2 of the} fuel-side porous portion 13 and the oxidant-side porous portion 14 and the rib width l ₁ ,
l ₂ has the same dimensions of 0.6 mm and 1.5 mm respectively, the fuel side porous portion 13 is made of a material having a porosity (ratio of void volume to the total volume) of 80%, and the oxidizer side porous portion 14 has a porosity of 60%. Example 1 except that materials were used
It has the same configuration as.

With this configuration, when operated under high current density conditions, the porosity of the fuel side porous portion 13 is about 1.3 times the porosity of the oxidant side porous portion 14, and the fuel side porous portion 1
Since the pore volume of No. 3 is large, the pores of Examples 1 and 2 are
The same effect can be obtained.

Example 4. The web thicknesses S ₁ and S ₂ and the rib widths l ₁ and l ₂ of the fuel-side porous portion 13 and the oxidant-side porous portion 14 are the same as 0.6 mm and 1.5 mm, respectively,
A material having an average pore diameter of 40 μm in the fuel side porous portion 13 (having a pore diameter distribution of FIG. 3a) and a material having an average pore diameter of the oxidizing agent side porous portion 14 of 20 μm (a pore diameter distribution of b in FIG. 3) The configuration was the same as in Example 1 except that

Next, the operation will be described. When operated under high current density conditions, the phosphoric acid fill level of the fuel side porous portion becomes high, as described in the operation of Example 1,
Although the fill level of the oxidant side porous part decreases, since the pore size of the oxidant side porous part is smaller than that of the fuel side porous part, the capillary in the direction of pulling back from the fuel side porous part to the oxidant side porous part. The suction power works. The capillary suction force is expressed by the following equation. ΔP = 2γ cos θ (R ₂ −R ₁ ) / R ₁ R ₂ Here, ΔP: capillary suction force, γ: surface tension, θ: contact angle, R ₁ , R ₂ ; pore size. Capillary suction force increases as the difference in pore size increases. Therefore, it is possible to prevent excessive deviation toward the fuel-side porous portion, and prevent overflow of phosphoric acid into the flow path at the fuel-side porous portion and deterioration of gas diffusivity.

Example 5. The web thicknesses S ₁ and S ₂ and the rib widths l ₁ and l ₂ of the fuel-side porous portion 13 and the oxidant-side porous portion 14 are the same as 0.6 mm and 1.5 mm, respectively,
The fuel side porous portion 13 is made of a material having an average pore diameter of 40 μm (the pore diameter distribution is a in FIG. 3). The oxidant side porous portion 14 has an average pore diameter of 40 μm, but the pore diameter distribution is shown in FIG. 2c. As shown, the same configuration as in Example 1 was used except that a broad (widely distributed) material was used.

Next, the operation will be described. When operated under a high current density condition, the phosphate fill level of the fuel-side porous portion 13 increases and the fill level of the oxidant-side porous portion 14 decreases, as described in the operation of the first embodiment.
Since the pore size distribution of the oxidant-side porous part 14 is broad, a slight change in the phosphate fill level of the oxidant-side porous part 14 causes a large change in the pore size of the part filled with the electrolyte. From the side porous portion 13 to the oxidant side porous portion 1
Capillary suction force works in the direction of returning to 4. Therefore, it is possible to prevent excessive deviation toward the fuel-side porous portion 13, and prevent overflow of phosphoric acid into the flow path in the fuel-side porous portion 13 and deterioration of gas diffusivity.

Embodiment 6 FIG. The web thicknesses S ₁ and S ₂ and the rib widths l ₁ and l ₂ of the fuel-side porous portion 13 and the oxidant-side porous portion 14 are the same as 0.6 mm and 1.5 mm, respectively,
A material having an average pore size of 40 μm in the oxidant-side porous part 14 (pore size distribution is a in FIG. 3) is used, and the average pore size of the fuel-side porous part 13 is 40 μm, but the pore size distribution is in c of FIG. As shown, the same structure as in Example 1 was used except that a broad material was used.

Next, the operation will be described. When operated under a high current density condition, the phosphate fill level of the fuel-side porous portion 13 increases and the fill level of the oxidant-side porous portion 14 decreases, as described in the operation of the first embodiment.
Since the pore size distribution of the fuel side porous portion 13 is broad, a slight change in the phosphate fill level of the fuel side porous portion 13 causes a large change in the pore diameter of the portion filled with the electrolyte. Capillary suction force acts in the direction of returning from the portion 13 to the oxidant side porous portion 14. Therefore, it is possible to prevent an excessive bias toward the fuel-side porous portion 13, and
It is possible to prevent the phosphoric acid from overflowing into the flow path in 3 and the deterioration of gas diffusivity.

Example 7. The web thicknesses S ₁ and S ₂ and the rib widths l ₁ and l ₂ of the fuel-side porous portion 13 and the oxidant-side porous portion 14 are the same as 0.6 mm and 1.5 mm, respectively,
The oxidizer-side porous portion 14 and the fuel-side porous portion 13 have an average pore diameter of 40 μm, but have the same configuration as in Example 1 except that a broad material is used as shown in FIG. .

Next, the operation will be described. When operated under a high current density condition, the phosphate fill level of the fuel-side porous portion 13 increases and the fill level of the oxidant-side porous portion 14 decreases, as described in the operation of the first embodiment.
Since the pore size distributions of the fuel-side porous portion 13 and the oxidant-side porous portion 14 are broad, the electrolyte is filled with a slight change in the phosphate fill level of the fuel-side porous portion 13 and the oxidant-side porous portion 14. Since the pore diameter of the existing portion changes greatly, the capillary suction force acts in the direction of returning from the fuel side porous portion 13 to the oxidant side porous portion 14. Therefore, it is possible to prevent excessive deviation toward the fuel-side porous portion 13, and
It is possible to prevent the overflow of phosphoric acid into the flow path and the reduction of gas diffusivity.

Example 8. Assembling a small single cell having a conventional structure for the structures of Example 1 to Example 7 and comparison,
The relationship between the phosphate level and the hydrogen gain was sought.
In the conventional configuration, a material having an average pore diameter of 40 μm (pore diameter distribution is a in FIG. 3) was used for both the fuel-side porous portion and the oxidant-side porous portion. The hydrogen gain is a characteristic difference when pure hydrogen and simulated reformed gas (80% H ₂ -20% CO ₂ ) are used as fuel, and is an index of gas diffusibility of the fuel electrode. FIG. 4 shows the results.

From FIG. 4, in the conventional example, the hydrogen gain becomes large when the phosphoric acid fill level exceeds 45% (line Ha
(See), while the gas diffusivity of the fuel side electrode decreases,
It can be seen that the cells of the present invention shown in Examples 1 to 7 exhibit stable characteristics up to a phosphoric acid fill level of about 60% (see line Hb). Therefore, with the configurations shown in Examples 1 to 7, it is possible to increase the phosphoric acid fill level up to 60% without lowering the gas diffusivity on the fuel side, and it is possible to secure a long life. Become.

[0040]

As described above, according to claim 1 of the present invention, a unit cell having a fuel electrode and an oxidant electrode that face each other with an electrolyte matrix in between, a dense layer, and a fuel gas and an oxidant on both sides thereof, respectively. In a fuel cell in which a plurality of layers are stacked via a gas separation plate composed of ribs that form channels that allow gas to flow in a direction orthogonal to each other and a porous portion formed of a web,
Since the volume occupied by the pores of the fuel side porous portion forming the fuel gas passage is made larger than the volume occupied by the pores of the oxidant side porous portion forming the oxidant gas passage, Since the phosphate fill level does not increase above a certain level, it is possible to prevent the electrolyte from overflowing into the fuel side flow path and prevent the gas diffusivity from decreasing in the fuel side porous part, and to secure a long life. There is an effect that a fuel cell that can store the electrolyte can be obtained.

According to the second aspect of the present invention, in the first aspect, since the thickness of the web on the fuel side porous portion is larger than the thickness of the oxidizer side web, the pore volume of the fuel side porous portion is increased. Is larger than the pore volume of the oxidant side porous portion.

According to a third aspect of the present invention, in the first aspect, the width of the rib of the fuel-side porous portion is made larger than the width of the rib of the oxidant-side porous portion. The volume becomes larger than the pore volume of the oxidant side porous portion.

Further, according to claim 4 of the present invention, in claim 1, the porosity of the fuel side porous portion is made larger than the porosity of the oxidant side porous portion. It is larger than the pore volume of the side porous portion.

According to the fifth aspect of the present invention, the pore size of the fuel-side porous portion forming the fuel gas passage is smaller than that of the oxidant-side porous portion forming the oxidant gas passage. Since it is made larger, it is possible to suppress the migration of the electrolyte from the oxidant side porous part to the fuel side porous part, and prevent the electrolyte from overflowing into the fuel side flow path and the deterioration of the gas diffusibility in the fuel side porous part. In addition to the above, there is an effect that a fuel cell capable of storing a sufficient amount of electrolysis to secure a long life is obtained.

According to the sixth aspect of the present invention, the average pore diameters of the fuel side porous portion forming the fuel gas flow passage and the oxidant side porous portion forming the oxidant gas flow passage are substantially equal and Since the pore size distribution of the fuel side porous part is broadened, when the phosphoric acid fill level of the fuel side porous part becomes high, the electrolyte can be pulled back toward the fuel side porous part and the oxidant side porous part. There is an effect that a fuel cell can be obtained which can prevent overflow into the side flow passage and decrease in gas diffusibility in the fuel side porous portion, and can store a sufficient amount of electrolyte to secure a long life.

According to the seventh aspect of the present invention, the average pore diameters of the fuel side porous portion forming the fuel gas flow passage and the oxidant side porous portion forming the oxidant gas flow passage are made substantially equal. Moreover, since the pore size distribution of the oxidant side porous part was broadened, when the phosphate fill level of the oxidant side porous part became low, it was caused by the difference in the phosphate fill level of the fuel side porous part and the oxidizer side porous part. Electrolyte can be pulled back to the oxidant side porous part by the capillary suction force, which can prevent the electrolyte from overflowing into the fuel side flow path and the decrease of gas diffusivity in the fuel side porous part, and long-term life. There is an effect that a fuel cell capable of storing a sufficient amount of electrolyte to secure the fuel cell is obtained.

According to the eighth aspect of the present invention, the average pore diameters of the fuel-side porous portion forming the fuel gas passage and the oxidant-side porous portion forming the oxidant gas passage are made substantially equal. And since the pore size distribution of the porous parts on both sides was made broad, when the phosphoric acid fill level of the fuel side porous part became high or when the phosphoric acid fill level of the oxidant side porous part became low,
The electrolyte can be pulled back toward the oxidant side porous part by the manual suction force caused by the phosphate fill level difference between the fuel side porous part and the oxidant side porous part, and the electrolyte overflows into the fuel side flow path, There is an effect that it is possible to obtain a fuel cell that can prevent a decrease in gas diffusibility in the fuel side porous portion and can store a sufficient amount of electrolyte to secure a long-term life.

According to a ninth aspect of the present invention, in any one of the first to eighth aspects, the storage amount of phosphoric acid in the fuel-side porous portion and the oxidant-side porous portion is equal to the pore volume of both porous portions. Since it is set to 40 to 60%, it is possible to secure a long service life without overflow of the electrolyte into the fuel side flow passage and deterioration of gas diffusivity in the fuel side porous portion.

[Brief description of drawings]

FIG. 1 is a perspective view showing a main part of a fuel cell according to a first embodiment of the present invention.

2A is a sectional view taken along line IIA-IIA in FIG. 1A, and FIG. 2B is a sectional view taken along line IIB-IIB in FIG.
It is shown in.

FIG. 3 is an explanatory view showing the pore distribution of the material used for the porous portion of the present invention.

FIG. 4 is an explanatory diagram showing a result of comparison of hydrogen gains, which is an index of gas diffusibility of a fuel electrode.

FIG. 5 is a perspective view showing a main part of a conventional fuel cell.

6 is a cross-sectional view taken along line VI-VI in FIG.

[Explanation of symbols]

1 Electrolyte Matrix, 2 Electrode Catalyst Layer (Fuel Electrode), 3 Electrode Catalyst Layer (Oxidizer Electrode), 4 Fuel Gas Flow Path, 5 Oxidizer Gas Flow Path, 7 Dense Layer, 12 Gas Separation Plate, 13 Fuel Side Porous Part , 13a web, 13b rib, 14 oxidant side porous portion, 14a web, 14b
rib.

Claims (9)

[Claims] 1. A unit cell having a fuel electrode and an oxidant electrode that face each other with an electrolyte matrix in between, a dense layer, and ribs that form flow paths on both sides of which a fuel gas and an oxidant gas can flow orthogonally to each other. In a fuel cell in which a plurality of gas separation plates composed of a porous portion made of a web are stacked, the volume occupied by the pores of the fuel-side porous portion forming the fuel gas passage is set to the oxidant gas passage. The fuel cell is characterized in that the volume is larger than the volume occupied by the pores of the oxidant-side porous portion forming the. 2. The thickness of the web on the fuel side porous portion is made thicker than the thickness of the web on the oxidizer side.
The fuel cell described in 1. 3. The width of the rib on the fuel side porous portion is made larger than the width of the rib on the oxidant side porous portion.
The fuel cell described in 1. 4. The fuel cell according to claim 1, wherein the porosity of the fuel side porous portion is larger than the porosity of the oxidant side porous portion. 5. A unit cell having a fuel electrode and an oxidant electrode that face each other with an electrolyte matrix in between, a dense layer, and ribs that form flow paths on both sides of which a fuel gas and an oxidant gas can flow orthogonally to each other. In a fuel cell in which a plurality of layers are stacked through a gas separation plate configured with a porous portion formed of a web, the pore diameter of the fuel-side porous portion that forms the fuel gas passage forms the oxidant gas passage. A fuel cell, characterized in that it is made larger than the pore diameter of the oxidant side porous portion. 6. A unit cell having a fuel electrode and an oxidant electrode that face each other with an electrolyte matrix in between, a dense layer, and ribs that form flow paths on both sides of which a fuel gas and an oxidant gas can flow at right angles to each other. In a fuel cell in which a plurality of layers are stacked via a gas separation plate composed of a porous portion composed of a web, a fuel side porous portion forming a passage for the fuel gas and an oxidant side forming a passage for the oxidant gas When the average pore diameters of the porous portions are almost equal and the distribution of the pore diameters of the fuel-side porous portion is broad, and the fill level of phosphoric acid in the fuel-side porous portion becomes high, the difference between the phosphoric acid fill levels in the porous portions on both sides is high. The fuel cell is characterized in that the phosphoric acid is drawn back toward the oxidant side porous portion due to the difference in capillary suction force caused by the above. 7. A unit cell having a fuel electrode and an oxidant electrode that face each other with an electrolyte matrix in between, a dense layer, and ribs that form flow paths on both sides of which a fuel gas and an oxidant gas can flow at right angles to each other. In a fuel cell in which a plurality of layers are stacked via a gas separation plate composed of a porous portion composed of a web, a fuel side porous portion forming a passage for the fuel gas and an oxidant side forming a passage for the oxidant gas When the average pore diameters of the porous parts are made substantially equal and the pore size distribution of the oxidant side porous part is broadened to lower the phosphoric acid fill level of the oxidant side porous part, the phosphoric acid fill of the both side porous parts is reduced. A fuel cell, wherein phosphoric acid is drawn back toward the oxidant-side porous portion due to a difference in capillary suction force caused by a level difference. 8. A unit cell having a fuel electrode and an oxidant electrode that face each other with an electrolyte matrix in between, a dense layer, and ribs that form flow paths on both sides of which a fuel gas and an oxidant gas can flow at right angles to each other. In a fuel cell in which a plurality of layers are stacked via a gas separation plate composed of a porous portion composed of a web, a fuel side porous portion forming a passage for the fuel gas and an oxidant side forming a passage for the oxidant gas The average pore diameters of the porous parts are made substantially equal and the pore size distributions of the porous parts on both sides are broadened so that the phosphoric acid fill level of the fuel side porous part becomes high and the phosphoric acid fill level of the oxidant side porous part becomes low. When it becomes, the fuel cell is characterized in that the phosphoric acid is pulled back toward the oxidant side porous portion due to the difference in the capillary suction force due to the difference in the phosphate fill level between the both side porous portions. 9. The storage amount of phosphoric acid in the fuel-side porous portion and the oxidant-side porous portion is 40 to 60% of the pore volume of both the porous portions.
The fuel cell according to any one of claims 1 to 7, wherein