JPH07192741A - Solid electrolyte fuel cell - Google Patents

Abstract

PURPOSE:To easily take out electric power from a cell stack in which a plurality of unit cells are connected in series. CONSTITUTION:A conductive part 21b constituted with a porous material is formed on the inner surface side of a supporting tube 21 formed electrically connecting in series a plurality of unit cells 22 each other on the outer surface, facing in the lengthy direction, of the supporting tube 21. The conductive part 21b and a unit cell 22B formed on one end side of a cell stack 20 are electrically passed, and the conductive part 21b of the supporting tube 21 is made as a lead on one end side of the cell stack 20. Electric power from the cell stack 20 is easily, surely taken out with low electric power loss by a unit cell 22A on the other end side and the conductive part 21b of the supporting tube 21 on the same side near the unit cell 22A.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel cell using a solid electrolyte.

[0002]

2. Description of the Related Art A solid oxide fuel cell has a solid electrolyte such as yttria-stabilized zirconia (YSZ) or calcia-stabilized zirconia (CSZ) sandwiched between, for example, an air electrode made of a perovskite-type lanthanum composite compound and nickel. A fuel electrode as a main component is provided, and an electromotive force is obtained by electrochemically reacting air and fuel gas which flow toward each of the electrodes with a solid electrolyte. In this type of fuel cell, it is necessary to separate the fuel gas flow path and the air flow path into an airtight state.
For example, there is known one in which a solid electrolyte is formed in a cylindrical shape, and electric power is obtained by a cylindrical single cell in which the electrodes are provided on the inner and outer surfaces thereof. In this case, since the electric power obtained by the unit cell is small, a plurality of unit cells electrically connected in series with each other are formed in a cylindrical cell stack, and electric power is obtained through the cell stack. There are many batteries.

FIG. 2 shows a cross section around the cell stack of such a conventional fuel cell. In the figure, reference numeral 1 is a cylindrical cell stack with one end closed, and the cell stack 1 is a long cylindrical porous base tube 2 and a short cylinder formed outside the base tube 2. -Shaped plurality of unit cells 3, a conductive interconnector 4 that electrically connects the unit cells 3 to each other in series, upper and lower leads 5 and 6 for extracting electric power, and a closing cap 7 at the lower end. Etc.

The unit cell 3 is formed by sandwiching a cylindrical solid electrolyte 3a between a fuel electrode 3b on the inner surface side and an air electrode 3c on the outer surface side. The air electrode 3c of the unit cell 3 on the upper side and the unit cell 3 on the lower side. The fuel electrode 3b of the cell 3 is connected by the interconnector 4. Then, the fuel electrode 3 of the uppermost unit cell 3
b is connected to the upper lead 5, and the air electrode 3c of the lowermost unit cell 3 is connected to the lower lead 6. The lower lead 6 is bent in a U-shaped cross section and extends inward of the base tube 2.

A fuel injection pipe 8 having a small diameter and conductivity is inserted into the inside of the cell stack 1 up to the vicinity of the closing cap 7, and between the base pipe 2 of the cell stack 1 and this fuel injection pipe 8. A fuel gas passage 9 is formed from the bottom to the top, and an air passage 10 is formed outside the cell stack 1 along the cell stack 1. In addition, a conductive felt 11 is arranged in the fuel gas flow passage 9 in the cell stack 1 so as to electrically connect the lower lead 6 and the fuel injection pipe 8, and is provided above the upper lead 5 and the fuel injection pipe 8. The collector wires 12, 13 are attached to the.

Therefore, in the cell stack shown in FIG. 2, the fuel gas flowing into the fuel gas flow path 9 through the fuel injection pipe 8 diffuses in the base tube 2 and the fuel electrode 3b of the unit cell 3 to form the solid electrolyte 3a. Reach one side. Further, the air flowing in the air flow path 10 diffuses in the air electrode 3c of the single cell 3 and reaches one side of the solid electrolyte 3a, and the oxygen thereof becomes ions to pass through the solid electrolyte 3a to pass through the fuel electrode 3b. When reaching the side, the oxygen ions and the fuel gas electrochemically react with each other to generate an electromotive force in the unit cell 3. Then, the electric power applied by the number of unit cells 3 is attached to the upper lead 5 and the electric lead 13 attached to the fuel injection pipe 8 from the lower lead 6 via the conductive felt 11. Taken out from and.

[0007]

In the above conventional fuel cell, since the unit cells 3 are connected in series, the electric power is taken out from the cell stack 1 by connecting the upper side and the lower side of the cell stack 1. Although it is necessary to use the terminal portion for taking out, in order to facilitate the use of the electric power after the electric power is taken out, it is desirable that the pair of current collectors 12 and 13 are located close to each other. For this reason, particularly when electric power is taken out from the lower side of the cell stack 1, it is necessary to pass through the lower side lead 6, the conductive felt 11, the fuel injection pipe 8 and the collecting wire 13. However, the conductive felt 11 has a relatively large resistance, and the power loss due to this becomes large when the power is taken out. At the same time, the conductive felt 11 sinters at a high temperature during operation, its elasticity decreases, and the lower side There is a problem that the contact with the lead 6 and the fuel injection pipe 8 is deteriorated.

Further, since the fuel injection pipe 8 needs to be made of a conductive material, the range of material selection is limited, and in order to prevent the flow of fuel gas from being disturbed, the collecting wire 13 is It is necessary to attach it to the upper end of the fuel injection pipe 8, but in this case, this collecting wire 13 and the cell stack 1
There was a problem that the distance between the current collecting wires 12 attached to the upper part of the above could not be sufficiently close.

The present invention has been made in view of the above circumstances, and a solid electrolyte from which electric power can be easily and reliably taken out from a cell stack in which a plurality of unit cells are connected in series in the longitudinal direction thereof without a large electric power loss. The purpose is to provide a fuel cell.

[0010]

In order to achieve the above-mentioned object, the present invention provides a unit cell in which a pair of electrodes are formed with a solid electrolyte sandwiched between them, and the unit cell is oriented on the outer surface of a porous insulator in the longitudinal direction thereof. A plurality of cylindrical cell stacks that are electrically connected to each other in series, and a fuel gas is supplied to one side inside and outside the cell stack, and air is supplied to the other side to generate electricity. In an electrolyte fuel cell, a conductive portion formed of a porous conductive material is formed on the inner surface side of the insulator, and the conductive portion and the single cell formed on one end side of the cell stack are electrically connected. The conductive portion serves as a lead on one side of the cell stack.

[0011]

Since the unit cells are electrically connected in series in the longitudinal direction of the cell stack, the electric power is taken out from this cell stack only at one end side and at the other end side of the cell stack. You need to do it from In this case, since the conductive part on the inner surface side of the insulator is electrically connected to the unit cell on the one end side, the power is taken out from this cell stack on the unit cell on the other end side and close to it. It may be performed from the conductive portion on the same side. That is, in this fuel cell, electric power can be taken out from two adjacent points on one end side of the cell stack by utilizing the conductive portion on the inner peripheral side of the insulator.

[0012]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a sectional view around a cell stack of a solid oxide fuel cell according to an embodiment of the present invention.

In the drawing, reference numeral 20 is closed at the lower end,
It is a cylindrical cell stack with an opening formed at the top,
The cell stack 20 includes a support tube 21, a unit cell 22, an interconnector 23, leads 24, protective films 25 and 26, a seal member 27, and a cap member 28. The support tube 21 has a double cylindrical structure made of a strong porous material, the outer surface side is an insulating portion 21a made of an insulating member, and the inner surface side is a conductive material,
For example, it is a conductive portion 21b made of the same material as the fuel electrode and the air electrode of the unit cell 22. On the outer surface of the insulating portion 21 a of the support tube 21, a plurality of short cylindrical unit cells 22 are formed which are arranged in the state of being close to each other in the longitudinal direction of the support tube 21.

The unit cell 22 is formed by sandwiching an inner surface side of a cylindrical solid electrolyte 22a with a fuel electrode 22b and an outer surface side with an air electrode 22c, and the fuel electrode 22b of the upper unit cell 22 and the lower unit cell. The air electrodes 22c of 22 are connected by a conductive interconnector 23, and the unit cells 22 are electrically connected in series with each other. In addition, the air electrode 22 of the uppermost unit cell 22A of the cell stack 20 is
A conductive lead 24 is electrically connected to c, and the fuel electrode 22 of the unit cell 22B at the bottom of the cell stack 20 is electrically connected.
The conductive portion 21b of the support tube 21 is electrically connected to b. Furthermore, the support tube 2 in which the unit cell 22 is formed
A cap member 28 is attached to the lower end of 1 via an insulating seal member 27, and the outer surfaces of the interconnector 23 and the lead 24 are covered with an insulating protective film 25.
It is covered by 26.

Further, the upper end of the cell stack 20 divides the first air chamber 30 and the first fuel gas chamber 31 into first partition plates 3.
4, a fuel injection pipe 37 is attached to the second partition plate 35, which is attached to the cell stack 20 and has an upper end portion which divides the first fuel gas chamber 31 and the second fuel gas chamber 32. It is inserted up to the vicinity of the closed portion 20a. The fuel injection pipe 37 is provided inside the cell stack 20.
A fuel gas flow path 38 is formed outside of the cell stack 2 and
An air flow path 39 is formed along the cell stack 20 in the first air chamber 30 outside 0. Further, a third partition plate 36 that divides the first air chamber 30 and the second air chamber 33 is provided below the cell stack 20, and the second air chamber 33 side is provided through a hole 36 a of the third partition plate 36. To the first air chamber 30
Air is supplied to the internal air flow path 39. 40, 41
Are current collecting wires attached to the leads 27 and 28, respectively.

Next, the operation of this fuel cell will be described. Air is supplied to the air flow path 39 in the first air chamber 30 from the second air chamber 33 side through the hole 36a of the third partition plate 36,
When the fuel gas is supplied from the first fuel gas chamber 31 side to the fuel gas flow path 38 in the cell stack 20 through the fuel injection pipe 37, the base tube 21 and the fuel electrode 22b of the unit cell 22 are supplied.
Fuel gas diffused inside and the air electrode 22c of the single cell 22
The air diffused therein electrochemically reacts with each other through the solid electrolyte 22a to generate an electromotive force in each unit cell 22. Then, the electric power obtained by adding the number of unit cells 22 from the cell stack 20 is taken out through the collecting wires 40 and 41 connected to the leads 27 and 28.

In this case, the pair of collector wires 40, 41 for extracting electric power from the cell stack 20 are connected to the leads 24, respectively.
Also, since they are connected to the upper end of the conductive portion 21b of the support tube 21 and are both close to the upper end of the cell stack 20, it is possible to facilitate the extraction of electric power from the cell stack 20. . In particular, since the conductive portion 21b of the support tube 21 is used as a lead for extracting electric power from the lowermost unit cell 20B side of the cell stack 20, the conductive felt 1 is used as this lead.
1 and the conventional fuel cell using the fuel injection pipe 8, the electric resistance is small and the power loss is small in extracting electric power, and the fuel injection pipe 8 does not need to be made of a conductive material. The width is widened to facilitate the production.

The used fuel gas is discharged from the cell stack 20 to the first fuel gas chamber 31 and then to the outside of the fuel cell, and the used air also reaches the vicinity of the first partition plate 34, and then the fuel is discharged. It is discharged to the outside of the battery.

As described above, in the fuel cell of this embodiment, it is not necessary to use the conductive felt 11 for extracting electric power from the cell stack, unlike the conventional fuel cell.
Power loss can be suppressed to a small level, and since there is no contact failure due to sintering, power can be reliably taken out. Further, since it is not necessary to use the fuel injection pipe 8 by utilizing the conductive portion 21b of the support pipe 21 for taking out the electric power, the fuel injection pipe 8 can be easily manufactured and the collector wire 4
Since 0 and 41 can be attached at positions close to each other on the upper end side of the cell stack 20, it is possible to easily take out electric power from the fuel cell.

In the present invention, the unit cell may be formed outside the porous insulator. Therefore, unlike the above embodiment, the support tube is made conductive and the conductive support tube is made conductive. An insulating film may be formed between the cell and the unit cell.

[0021]

As is apparent from the above description, according to the present invention, the inner surface side of the insulator, on the outer surface of which a plurality of unit cells are formed, is made of a porous conductive material in the longitudinal direction. Since the conductive portion is made to be a lead on one side of the cell stack by conducting the conductive portion and the single cell formed on one end side of the cell stack, Power out of
This can be performed by the unit cell on the other end side of this cell stack and the conductive section on the same side that is close to the unit cell, and power can be taken out easily. Further, since it is not necessary to use the conductive felt for extracting the electric power, it is possible to suppress the electric power loss at the time of extracting the electric power and to surely take out the electric power.

[Brief description of drawings]

FIG. 1 is a cross-sectional view around a cell stack of a fuel cell according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view around a cell stack of a conventional fuel cell.

[Explanation of symbols]

20 ... Cell stack, 21 ... Support tube, 21b ... Conductive part, 22 ... Single cell, 22a ... Solid electrolyte, 22b ...
Fuel cell (electrode), 22c ... Air electrode (electrode).

Front Page Continuation (72) Inventor Riki Iwasawa 1-5-1, Kiba, Koto-ku, Tokyo Fujikura Ltd. (72) Inventor Satoru Yamaoka 1-1-5, Kiba, Koto-ku, Tokyo Fujikura Ltd.

Claims (1)

[Claims] 1. A plurality of unit cells, each having a pair of electrodes sandwiching a solid electrolyte, are formed on the outer surface of a porous insulator in a state of being electrically connected in series in the longitudinal direction thereof. In a solid oxide fuel cell including a tubular cell stack, in which fuel gas is supplied to one side inside and outside of the cell stack, and power is generated by flowing air to the other side, a porous conductive layer is formed on the inner surface side of the insulator. Forming a conductive portion composed of a conductive material, and electrically connecting the conductive portion and a single cell formed on one end side of the cell stack, and using this conductive portion as a lead on one side of the cell stack A solid electrolyte fuel cell characterized by the above.