JP2000306590A - Solid electrolyte fuel cell - Google Patents

Abstract

(57) [Summary] (Modified) [PROBLEMS] A solid electrolyte fuel cell capable of uniformly supplying a fuel gas and an oxidizing gas to a flat cell to obtain high power generation efficiency. An accommodating portion for accommodating a flat cell is formed in the center of a ceramic separator, and a fuel gas supply passage, a fuel gas exhaust passage, and a fuel gas exhaust passage are provided around the accommodating portion. , An oxidizing gas supply passage 18 and an oxidizing gas exhaust passage 20 are formed.
The fuel gas exhaust passage 16 and the exhaust passage 16 for fuel gas are formed to face each other with the housing portion 12 interposed therebetween, and are formed to have substantially the same length in parallel with the sides of the housing portion 12 facing each other. Supply passage 18 and oxidant gas exhaust passage 20
The solid electrolyte fuel cell is formed in parallel with the opposite side of the portion where the is formed and at substantially the same length as that side.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid electrolyte fuel cell capable of uniformly supplying a fuel cell and an oxidizing gas to a flat plate type cell and obtaining high power generation efficiency.

[0002]

2. Description of the Related Art Recently, fuel cells which directly convert chemical energy inherent in fuel into electric energy by using, for example, air and hydrogen as oxidizing gas and fuel gas, respectively, have attracted attention from the viewpoint of resource saving and environmental protection. Research and development are progressing because solid electrolyte fuel cells have many advantages such as high power generation efficiency and effective use of waste heat.

A solid electrolyte fuel cell is composed of a flat cell having an air electrode and a fuel electrode, and a separator having an air supply / exhaust hole. A plurality of such flat cells and separators are stacked to form a stack. Used as

[0004] In the flat cell type, an air electrode of (La, Sr) MnO ₃ is provided on one surface of a flat solid electrolyte layer made of a zirconia sintered body (YSZ) doped with yttria or the like.
The fuel electrode of Ni / YSZ cermet is arranged on the other surface.

FIG. 6 is a perspective view of a separator used in a conventional solid electrolyte fuel cell of the internal manifold type. The separator 100 is a composite separator and includes a main body 60 and a current collector 61 made of a conductive oxide.

The main body 60 is made of lanthanum chromite oxide LaCrO ₃ doped with strontium.
A recessed pocket portion 62 is formed on the surface, into which the current collecting portion 61 is fitted as shown by the arrow in the figure.

The main body 60 has a rectangular shape, and gas supply / exhaust holes 64 to 70 are formed at four corners. An air supply hole 64 and an exhaust hole 66 are air supply and exhaust holes for air, and are provided in one diagonal direction, and a gas supply hole 68 and an exhaust hole 70 for fuel gas are provided in the other diagonal direction.

On the surface of the current collecting portion 61, a plurality of gas flow grooves 63 for uniformly flowing an oxidizing gas such as air are formed. Although not shown, a fuel gas flow groove is similarly formed on the back surface of the main body 60. Further, a conductive member is filled in the conductive hole 69 formed at the center of the pocket portion 62, and the front and back are electrically connected.

By alternately stacking such separators 100 and flat plate cells and supplying fuel gas and air to each passage, a fuel gas and an oxidizing gas are applied to each electrode surface of each flat plate cell. Contact and generate electromotive force.

For example, on the surface shown in FIG. 6, air flows from the left air supply hole 64 to the left dent 65 of the main body 60,
1 through the gas flow groove 63 and the dent 6 on the opposite side (right side).
7, and flows into the exhaust hole 66 on the right side. Similarly, on the back surface of FIG. 6, the fuel gas flows between the air supply holes 68 and 70 provided in different diagonal directions, and the main body 6
The fuel cell passes through a fuel gas flow groove (not shown) provided on the back surface of the fuel cell 0 to generate an electromotive force.

[0011]

However, the oxidizing gas and the fuel gas supplied to the flat cell from each of the air supply holes 64 and 68 of the separator 100 are not separated by the separator 10.
Since the gas is supplied from the corner of 0, each gas spreads radially from the air supply hole and reaches the flat plate cell. For this reason, the concentration of the gas supplied to the flat unit cell is low, for example, the concentration of the gas is high in the portion close to the air supply hole, while the concentration of the gas is low in the portion far from the air supply hole. It was uneven depending on the location of the cell.

As described above, if the fuel gas and the oxidizing gas are not supplied to the respective surfaces of the flat plate cell at a uniform concentration, a gas which is not used for power generation is generated in a portion where the gas concentration is high, and In a part where the concentration is low, the power generation capacity of the flat cell is not fully used, for example, the power generation in the flat cell is not performed as designed, and the power generation efficiency is reduced.

SUMMARY OF THE INVENTION An object of the present invention is to provide a solid electrolyte fuel cell which prevents uneven supply of each gas and has high efficiency.

[0014]

According to the present invention, in the conventional solid electrolyte fuel cell, since the fuel gas and the oxidizing gas flow in the diagonal direction of the separator, the supply of each gas becomes uneven. Focusing on the point, in order to solve the above problems, a solid oxide fuel cell was configured as follows.

That is, in a solid electrolyte fuel cell comprising a flat cell having a fuel electrode and an air electrode on both sides of a solid electrolyte layer, a ceramic separator and an alloy separator, the ceramic separator is a flat cell. A housing portion for housing the central portion, a plurality of grooves through which fuel gas flows at the bottom of the housing portion, and a fuel gas passage extending through the groove, parallel to a side of the housing portion, and extending over substantially the same length as the side. A passage is provided, and the alloy separator is provided with a groove provided on a surface facing the air electrode, and an oxidizing member communicating with the groove and extending in parallel with one side of the surface facing the air electrode and substantially the same length as this side. And an agent gas passage.

Thus, a passage through which each gas is sent out,
Since the exhaust passage is formed in parallel with the flat-plate unit cell and over substantially the same length as the side of the flat-plate unit cell, fuel gas and oxidizing gas are uniformly supplied to the entire flat-plate unit cell. , A constant concentration can be maintained, and power generation efficiency can be improved.

In addition, a sealant is attached to the periphery of the flat cell, so that when the flat cell is accommodated in the accommodating portion of the ceramic separator, the periphery of the flat cell is sealed. As a result, it is possible to prevent mixing of the fuel gas and the oxidizing gas, prevent combustion of the fuel gas and the oxidizing gas in the stack, and prevent damage to the stack or the like due to a local temperature rise and decrease in the efficiency of the fuel cell. .

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the fuel cell according to the present invention will be described.

1 and 2 are cross-sectional views of an internal manifold type solid electrolyte fuel cell.

The fuel cell 2 includes a ceramic separator 4
And a plurality of unit cells 10 configured by combining an alloy separator 6 and a flat plate type cell 8.
The ceramic separator 4 or the alloy separator 6 is an integrated internal manifold type solid electrolyte fuel cell having functions of supply and exhaust, distribution, and electrical connection of each gas of air and fuel.

The ceramic separator 4 is substantially square and made of a ceramic material such as lanthanum chromite-based oxide LaCrO ₃ doped with strontium, calcium, magnesium and the like. As shown in FIG. 5, a housing 12 for housing the flat cell 8 is formed at the center of the ceramic separator 4. A fuel gas supply passage 14 and a fuel gas exhaust passage are provided around the housing 12. 16
In addition, an oxidizing gas supply passage 18 and an oxidizing gas exhaust passage 20 are formed.

The storage section 12 is formed in a square shape substantially equal to the flat cell 8. The bottom of the storage section 12 extends along the direction from the fuel gas supply passage 14 to the fuel gas exhaust passage 16. A groove 13 is formed on the entire bottom surface, and a conductive hole 11 for filling a conductive material is formed at the center.

The fuel gas supply passage 14 and the fuel gas exhaust passage 16 are formed so as to face each other with the housing portion 12 interposed therebetween, and are formed to have substantially the same length in parallel with the sides of the housing portion 12 facing each other. It is. In addition, passages 34 and 36 are formed inside the fuel gas supply passage 14 and the fuel gas exhaust passage 16. The passages 34, 36 open into the groove 13 and
Steps 30 and 31 are formed as shown in FIG.
The passages 34 and 36 are provided by the fuel gas supply passages 1 and 0
4 and the exhaust passage 16 for fuel gas.

The alloy separator 6 is made of a heat-resistant alloy. As shown in FIG. 4, a plurality of grooves 15 are formed on the back side along the direction from the oxidizing gas supply passage 18 to the oxidizing gas exhaust passage 20. It is formed. The groove 15 is formed in a portion having substantially the same shape as the flat cell 8 so as to face the air electrode when the flat cell 8 is stacked. The oxidizing gas supply passage 18 and the oxidizing gas exhaust passage 20
The groove 15 is formed in parallel with the facing side of the place where the groove 15 is formed, and has substantially the same length as that side.

Inside the supply passage 18 for oxidizing gas and the exhaust passage 20 for oxidizing gas, passages 38 and 40 opening to the groove 15 are formed. Further, steps 32, 33 are formed between the oxidizing gas supply passage 18 and the passage 38 and between the oxidizing gas exhaust passage 20 and the passage 40, as shown in FIG. The passages 33 and 40 communicate with the oxidizing gas supply passage 18 and the oxidizing gas exhaust passage 20 through 33.

As shown in FIG. 5, the flat-plate unit cell 8 is a support-membrane unit cell. The unit cell is a fuel electrode made of Ni / YSZ cermet as a support, and a YSZ electrolyte,
(La, Sr) MnO ₃ air electrode (none shown)
And are formed in this order. Flat cell 8
A seal member 9 made of a glass material is provided around the inside of the housing portion 12, and when it is housed in the housing portion 12, it comes into close contact with the inner surface of the housing portion 12 and the alloy ceramic 6. Note that the sealing material 9 may be softened or melted by a rise in temperature during power generation or the like, thereby closing the gap. In addition, the sealing material 9 is not made of glass, and may be other material as long as it is a material that seals the gap, such as metal brazing.

Next, the operation of the fuel cell 2 will be described.

As shown in FIG. 1 or FIG. 2, the fuel cell 2 has ceramic separators 4, unit cells 8, and alloy separators 6 alternately stacked, and a predetermined load or the like is applied vertically.
Seal the gap between each other. Then, the fuel gas supply passage 14, the fuel gas exhaust passage 16, the oxidant gas supply passage 18, and the oxidant gas exhaust passage 20 of each of the ceramic separator 4 and the alloy separator 6 communicate with each other in the vertical direction, and the fuel cell Four gas passages are formed in the inside of the tube 2 in the vertical direction.

When the fuel gas is supplied to the fuel gas supply passage 14, the fuel gas is supplied as shown by the arrow in FIG.
The gas flows through the groove 13 through the passage 34 through the stepped portion 30, and comes into contact with the fuel electrode of the flat plate cell 8. The fuel gas in contact with the fuel electrode of the flat plate cell 8 passes through the groove 13, passes through the passage 36, flows from the step 31 into the fuel gas exhaust passage 16,
Exhausted.

When air is supplied to the oxidizing gas supply passage 18 as shown in FIG. 2, the air passes through the step 32,
It flows into the groove 15 from the passage 38 and comes into contact with the air electrode of the flat cell 8. The air that has come into contact with the air electrode of the flat plate cell 8 passes through the groove 15, passes through the passage 40, flows into the oxidant gas exhaust passage 20 from the step 33, and is exhausted.

After the fuel cell 2 is heated to a predetermined temperature and the fuel gas and the air are brought into contact with the fuel electrode and the air electrode of the flat cell 8 in this way, the flat cell 8
Power generation is performed by connecting each cell 10 in series,
Current can be extracted.

As described above, according to the fuel cell 2, the passage of each gas is formed in parallel with each side of the flat cell 8 and at substantially the same length as each side. In addition, since the oxidizing gas such as air and the like uniformly comes into contact with the flat cell 8, an efficient power generation operation can be realized.

[0033]

According to the fuel cell of the present invention, the passage for supplying and exhausting fuel gas and oxidizing gas to and from the flat unit cell is parallel to the flat unit cell and the length of the flat unit cell. Since these gases are formed almost equally, these gases are evenly supplied to the entire surface of the flat-plate unit cell, sufficient power is generated over the entire flat-plate unit cell, and a solid electrolyte fuel cell having high power generation efficiency is provided. Can be.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a fuel cell according to the present invention.

FIG. 2 is a sectional view showing a fuel cell according to the present invention.

FIG. 3 is a plan view showing a ceramic separator.

FIG. 4 is a plan view showing an alloy separator.

FIG. 5 is an exploded perspective view showing a unit cell.

FIG. 6 is an exploded perspective view showing a conventional unit cell.

[Explanation of symbols]

 Reference Signs List 2 fuel cell 4 ceramic separator 6 alloy separator 8 flat cell 10 cell 12 housing 14 fuel gas supply passage 16 fuel gas exhaust passage 18 oxidant gas supply passage 20 oxidant gas exhaust passage 30, 31, 32, 33 step 34, 36, 38, 40 passage

Claims (5)

[Claims] 1. A flat cell having a fuel electrode and an air electrode disposed on the front and back surfaces of a flat solid electrolyte layer, and a separator having gas supply / exhaust holes for supplying each gas to the flat cell. Are alternately stacked, and in a solid electrolyte fuel cell that generates power by distributing fuel gas and oxidizing gas to the flat cell through the air supply and exhaust holes, the separator includes a first separator and a second separator, The first separator has a housing portion for housing the flat cell in a central portion thereof, and a fuel gas supply hole and a fuel gas exhaust hole, and an oxidant gas supply hole and an oxidant gas exhaust hole sandwiching the accommodation portion. A hole is formed parallel to and substantially the same length as the periphery of the housing portion with the holes facing the periphery of the housing portion, and the fuel gas supply hole and the fuel gas exhaust hole are formed at both ends of the housing portion. Open to each The second separator has the same fuel gas supply hole, fuel gas exhaust hole, oxidant gas supply hole, and oxidant gas exhaust hole as the first separator, and the second separator A gas passage groove is formed at a position corresponding to the storage portion when the separator and the first separator are stacked, and a passage is provided for opening an oxidant gas supply hole and an oxidant gas exhaust hole at both ends of the gas passage groove. A solid electrolyte fuel cell characterized by having a configuration as described above. 2. The solid electrolyte according to claim 1, wherein a passage of the first separator is formed on a back surface of the housing portion, and a passage of the second separator is formed on a back surface of the gas conducting groove. Fuel cell. 3. The solid oxide fuel cell according to claim 1, wherein the first separator is formed of ceramic, and the second separator is formed of a conductive alloy. 4. A sealing material made of glass is provided between the storage section and the flat cell to prevent mixing of the fuel gas and the oxidizing gas between the storage section and the flat cell. 4. The method according to claim 1, wherein
Item 6. The solid electrolyte fuel cell according to item 1. 5. The unit cell according to claim 1, wherein said flat plate type cell is a support membrane type cell using a fuel electrode as a support.
5. The solid electrolyte fuel cell according to any one of 4.