JPH0722061A - Solid electrolyte fuel cell - Google Patents

Abstract

PURPOSE:To provide a solid electrolyte fuel cell in which power can be taken out, without great power loses, from a cylindrical cell stack comprising a plurality of unit cells connected in series. CONSTITUTION:Even lines of unit cell groups G1, G2 with circular cross section are formed in a cell stack 20 with insulators therebetween, and the blocked- portion-side unit cell 22A of the first group G1 in the stack 20 is connected in series with the blocked-portion-side unit cell 22B of the second group G2 in the stack 20. The unit cells 22 in each of the groups G1, G2 are connected in series with one another. All the unit cells 22 in the stack 20 are therefore connected in series with one another and leads 27, 28 for taking out power from the cell stack 20 can be shortened accordingly. Therefore power losses caused by the resistances of the leads 27, 28 can be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid oxide 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 a single cell is small, a plurality of single 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. 3 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, a cap 7 and the like. It consists of

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

A small-diameter electrically conductive fuel injection pipe 8 is inserted into the inside of the cell stack 1 up to the vicinity of the closing cap 7, and the space between the base pipe 2 of the cell stack 1 and this fuel injection pipe 8 is from below. A fuel gas flow channel 9 is formed upward, and an air flow channel 1 is provided outside the cell stack 1.
0 is formed. In addition, a conductive felt 11 is housed 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 the upper lead 5 and the fuel injection pipe 8 are provided above. Is a collecting wire 12,
13 is attached.

Next, the operation of this fuel cell will be described. The fuel gas flowing through 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 single cell 3,
It reaches one side of the solid electrolyte 3a. 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. Reaching the side,
The oxygen ions and the fuel gas react electrochemically 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.

It should be noted that, in generating electricity, heat is generated in the unit cell 3 and the temperature of the cell stack 1 rises and thermally expands. However, the upper side of the cell stack 1 is fixed and the thermal expansion is escaped downward. Cell stack 1
Is closed at its lower end, the fuel gas is once introduced to the lower side of the cell stack 1 through the fuel injection pipe 8, and then is made to flow in the same direction as the air in the cell stack 1.

[0008]

In the above-mentioned conventional fuel cell, in order to take out electric power from the plurality of unit cells 3 in the cell stack 1, it is necessary to take out electric power from the upper side and the lower side of the cell stack 1. However, in order to facilitate the use of the electric power after the electric power is taken out, it is desirable that the pair of collector wires 12 and 13 are located close to each other. Therefore, 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, and the lower side lead 6 to the collecting wire 13 There was a problem that the distance to became long. Therefore, there is a problem in that the resistance of the lead portion for extracting power on the lower side becomes large and the power loss at this lead portion becomes large.

The present invention has been made in view of the above circumstances, and provides a solid oxide fuel cell in which electric power can be taken out from a cylindrical cell stack in which a plurality of unit cells are connected in series without a large electric power loss. That is the purpose.

[0010]

In order to achieve the above-mentioned object, the present invention provides a plurality of unit cells each having a pair of electrodes sandwiching a solid electrolyte on the outer surface of a support tube whose one end is closed. In the solid oxide fuel cell in which the unit cells are formed and connected in series, the outer surface of the support tube is divided into an even number of regions by a band-shaped insulator provided along the axial direction, and each of these regions is formed. In the region, a plurality of unit cells having arcuate cross sections connected in series along the axial direction are formed, and unit cells in each region on the closed end side of the support pipe are connected in series, and further, The lead is drawn from one electrode of one unit cell on the opening end side of the support tube and the other electrode of the other unit cell.

[0011]

For example, a tie having an outer surface of the support tube divided into two regions by a belt-shaped insulator provided along the axial direction, and formed on one surface of the outer surface of the support tube divided by the insulator. The closed-end-side single cell of the single cell group in the first column and the closed-end-side single cell of the single cell group in the second row formed on the other side are connected in series, and Since each single cell in the cell group is connected in series,
All the unit cells in one unit cell group are connected in series with each other. Therefore, in order to extract the electric power from this cell stack, the leads are drawn from the anode side and the cathode side of the pair of unit cells facing each other in the unit cell groups in the first and second rows on the opening end side of the support tube. Made by. Therefore, the lead for extracting electric power from the cell stack may be short.

[0012]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a longitudinal sectional view around a cell stack of a solid oxide fuel cell which is an embodiment of the present invention, and FIG. 2 is a lateral sectional view of this cell stack.

In the drawings, reference numeral 20 is a closing portion 20 at the lower end.
It is a cylindrical cell stack in which a is formed and an opening is formed at the upper end. The cell stack 20 includes a support tube 21,
Unit cell 22, interconnector 23, protective films 25, 26,
It is composed of leads 27, 28 and an insulator 29. The support tube 21 is made of a strong porous material (for example, a porous alumina tube) and has a cylindrical shape with a closed lower end. Two thin insulators 29 are attached to the outer surface of the support pipe 21 in the longitudinal direction at 180 degrees apart from each other, and the two insulators 29 are connected to each other at a closed portion of the support pipe 21. Has become. On the outer surface of the support tube 21 divided into two by the insulator 29, a plurality of short semi-cylindrical unit cells 22 (which are arranged close to each other in the longitudinal direction of the support tube 21 ( These are hereinafter referred to as single cell groups) are formed in two rows.

The unit cell 22 is a semi-cylindrical solid electrolyte 22a.
Is formed by sandwiching the inner surface side of the single electrode 22c between the fuel electrode 22b and the outer surface side of the air electrode 22c, and the adjacent single cells 22 in the single cell group G1 in the first row are the air electrodes 22c of the upper single cells 22. And the fuel electrode 22b of the lower unit cell 22 are electrically connected by a half-ring interconnector 23, and the adjacent unit cells 22 in the unit cell group G2 in the second row are the lower unit cells 22. The air electrode 22c and the fuel electrode 22b of the upper unit cell 22 are electrically connected by the interconnector 23.

In addition, the solid electrolyte 22a and the fuel electrode 22b of the lowermost unit cell 22B in the unit cell group G2 in the second row.
Is the single cell group G1 in the first row through the closed portion of the support tube 21.
The fuel electrode 22b of the unit cell 22B and the air electrode 22 of the unit cell 22A reach up to the vicinity of the lowest unit cell 22A.
and c are electrically connected by the interconnector 23.

Further, a lead 27 is attached to the fuel electrode 22b of the uppermost unit cell 22 in the unit cell group G1 in the first row, and the air electrode of the uppermost unit cell 22 in the unit cell group G2 in the second row is attached. A lead 28 is attached to 22c.
The outer surfaces of the interconnector 23 and the leads 27, 28 are covered with insulating protective films 25, 26.

That is, each unit cell 22 in the unit cell group G1 in the first row is electrically connected in series with the upper lead 27 as the cathode side and the air electrode 22c of the unit cell 22A located at the bottom as the anode side. Each unit cell 22 in the unit cell group G2 in the second row is electrically connected in series with the fuel electrode 22b of the unit cell 22B located at the bottom as the cathode side and the upper lead 28 as the anode side. Has been done. Further, the air electrode 22c of the unit cell 22A in the unit cell group G1 of the first row and the fuel electrode 22b of the unit cell 22B in the unit cell group G2 of the second row are electrically connected by the extension of the fuel electrode 22b. As a result, the single cell group G1 in the first column and the single cell group G2 in the second column are electrically connected in series.

Further, the upper end of the cell stack 20 divides the first air chamber 30 and the first fuel gas chamber 31 into the first partition plate 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 support pipe 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. Since the single cell group G1 in the first row connected in series with each other and the single cell group G2 in the second row similarly connected in series with each other of the cell stack 20 are connected in series with each other, this cell Electric power is taken out from the stack 20 through the collecting wires 40 and 41 connected to the leads 27 and 28.

In this case, the lead 2 of the cell stack 20
Since 7 and 28 are connected to the two single cells 22 formed on the uppermost part of the cell stack 20, the length thereof is short and the resistance of the leads 27 and 28 is also small. Therefore, in this fuel cell, it is possible to take out the electric power to the outside while suppressing the electric power loss due to the leads 27 and 28 to be small. Further, in this cell stack 20, the number of single cells, which is twice as large as that of the conventional cell stack, is connected in series, so that the voltage is increased accordingly. 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 to the outside of the fuel cell. Is discharged.

As described above, in the fuel cell of this embodiment, it is not necessary to take a long lead for taking out electric power from the cell stack as in the conventional fuel cell, so that the electric power loss due to the lead can be suppressed to be small. The power generation efficiency can be increased. Further, in the fuel cell of this embodiment, the number of the single cells 22 connected in series in the cell stack 20 can be increased by an even number as compared with the conventional fuel cell, so that the extraction voltage from the fuel cell is increased. be able to. In addition, in this embodiment, the case where the fuel cell has one cell stack 20 has been described, but a fuel cell including a plurality of similar cell stacks 20 and connecting these in series or the like with a collecting wire is also possible. Of course good things.

[0022]

As is apparent from the above description, according to the present invention, all the unit cells in the unit cell group having an even number of arcuate sections formed in the longitudinal direction of the cell stack are connected in series with each other. Since the lead for taking out the electric power from the cell stack can be shortened, the power loss caused by the resistance of the lead can be suppressed to be small. Therefore, the power generation efficiency of the fuel cell can be improved.

[Brief description of drawings]

FIG. 1 is a vertical 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 of this cell stack.

FIG. 3 is a vertical sectional view around a cell stack of a conventional fuel cell.

[Explanation of symbols]

20 ... Cell stack, 20a ... Blocking part, 22 ... Single cell, 22A ... Single cell (blocking part side single cell), 22B ...
Single cell (single cell on closed side), 22a ... Solid electrolyte,
22b ... Fuel electrode (electrode), 22c ... Air electrode (electrode), 27, 28 ... Lead, G1 ... Single-row single cell group, G2 ... Second-row single cell group.

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

Claims (1)

[Claims] 1. A solid electrolyte fuel in which a plurality of unit cells each having a pair of electrodes sandwiching a solid electrolyte are formed on the outer surface of a support tube whose one end is closed, and the unit cells are connected in series. In the battery, the outer surface of the support tube is divided into an even number of regions by a band-shaped insulator provided along the axial direction, and each of these regions has an arcuate cross section connected in series along the axial direction. A plurality of unit cells are formed, the unit cells in each region on the closed end side of the support pipe are connected in series, and one electrode and the other of the unit cells on the open end side of the support pipe A solid oxide fuel cell, in which a lead is drawn from the other electrode of the unit cell.