JPH06243879A - Solid electrolyte fuel cell - Google Patents

Abstract

PURPOSE:To increase mechanical strength as well as to make electrical connection excellent by engaging a plurality of single type cells/aggregates of base substances with one another via intercomectors so as to be formed into a stack where each base substance of the cells is formed into the tapered pipe with a porous thick wall. CONSTITUTION:A groove to which energizing seal rings 17 and 18 are put in, is formed in the inner circumference of the wide opening of a base substance 11 composed of an alloy whose thermal expansion coefficient is low, where the base substance is processed into a tapered pipe with its wall kept as thin as 2 to 3mm. In order that a plurality of single type cells/aggregates of base substances are engaged with one another via interconnectors 19, electrical connection is made excellent with the energizing ring 17 softened using Ag capable of being softened at working temperatures, and aluminum silica g1.ass is used for the seal ring 18 where the ring is fused so as to be sealed. By this constitution, it is thereby possible that mechanical strength is increased, and the mutual mechanical and electrical connection of the single type cells/the aggregates of base substances are made excellent together with the interconnectors.

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, and more particularly to a cell structure of a solid oxide fuel cell.

[0002]

2. Description of the Related Art A solid oxide fuel cell is a battery using a solid electrolyte such as zirconia, and has a capacity of 800 to 1000.
Since it operates at a high temperature of ℃, it has high power generation efficiency, requires no catalyst, and has a solid electrolyte that makes it easy to handle. It is expected as a third-generation fuel cell. There is.

Most of the solid oxide fuel cells are composed of ceramic materials. Therefore, the development of the solid oxide fuel cells depends largely on the ceramic material technology, and is often restricted by the ceramic material technology. . However, due to recent advances in ceramics material technology, the development of solid oxide fuel cells has come to the forefront of attention.

Currently, flat plate type, cylindrical type, monolithic type, etc. are being developed, and the cylindrical cell of Westinghouse is known as the one that is most practically used.
In the 1970s, a tapered tube type solid oxide fuel cell, which belongs to a cylindrical deformation, was developed. FIG. 6 is a cross-sectional view showing a conventional taper tube type solid oxide fuel cell.
A free-standing membrane type solid electrolyte body 41 composed of (ZrO ₂ ) _0.92 (Y ₂ O ₃ ) _0.04 (Yb ₂ O ₃ ) _0.04 and lanthanum bismuth nickelite La
(Bi) NiO ₃ or lanthanum strontium manganite La
From a cathode 43 made of (Sr) MnO ₃ , an anode 42 made of nickel Ni, and an interconnector 44 made of lanthanum strontium nickel chromite La (Sr) Cr (Ni) O ₃ or lanthanum strontium manganite La (Sr) MnO _3. The cell size is 25mm in diameter, 12mm in height,
The thickness is 0.4 mm.

This type of battery has the advantages that the cell structure is simple, that the size of the cell is an appropriate size in terms of ceramics manufacturing technology, and mass productivity is high, and that the shape of the cell facilitates stacking. there were.

[0006]

However, such a conventional taper tube type solid electrolyte fuel cell uses a self-supporting membrane type solid electrolyte body, so that the mechanical strength of the solid electrolyte fuel cell is not sufficient. Since the thickness was 0.4 mm, which was thin, it was not possible to perform taper processing with high accuracy, and therefore there was a problem that the gas sealing property at the connecting portion of the taper was insufficient and electrical contact was also insufficient.

The present invention has been made in view of the above points, and an object thereof is to improve the taper tube type cell, to provide not only the advantages of the conventional taper tube type cell but also to have excellent mechanical strength, gas sealability and electric property. The object of the present invention is to provide a solid oxide fuel cell that is excellent in electrical connectivity.

[0008]

According to the present invention, there is provided a taper tube type solid oxide fuel cell,
(1) Single cell / base assembly, and (2) housing are included, the base is a thick porous taper tube, and the single cells are laminated on a predetermined outer circumference, and the single cell is a solid electrolyte. A body is sandwiched between a cathode and an anode, and a plurality of single cell / substrate assemblies are fitted to each other via an interconnector to form a stack, and a housing supports and fixes the stack to form a stack. This is achieved by allowing the oxidant gas and the fuel gas to separately flow inside and outside.

[0009]

The single cell / base assembly, which is a unit of the solid electrolyte fuel cell stack, uses a thick base as a support, so that a solid electrolyte fuel cell having high mechanical strength and robustness can be obtained.
Further, the base body is easily machined, and the mechanical and electrical connection between the single cell / base body aggregate can be improved together with the interconnector.

[0010]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a sectional view showing a unit cell / substrate assembly of a solid oxide fuel cell according to an embodiment of the present invention. FIG. 2 is a cross-sectional view showing an interconnector of a solid oxide fuel cell according to an embodiment of the present invention together with a main part of a single cell / base assembly.

The unit cell / base body assembly is a base body 11 which is a porous and thick tapered tube and a unit cell 1 laminated on the outer surface thereof.
It consists of 5. The single cell has a cathode 12 and a solid electrolyte body 13.
And the anode 14. The base 11 is a heat-resistant alloy having a low coefficient of thermal expansion, that is, a Ni base alloy containing 20 to 30% of Mo and 7 to 12% of Cr or a Ni base alloy containing 20 to 30% of W and 7 to 12% of Cr. An alloy is used to prepare a thickness of 2 to 3 mm. In both cases, the coefficient of thermal expansion is 800 ° C. and is (12 to 15) × 10 ⁻⁶ / ° C. The base 11 is precision processed into a tapered shape. A fitting groove is formed on the inner circumference of the wide mouth of the base body for fitting the O-ring 17 for conduction and the O-ring 18 for sealing, which are interconnectors 19. For the O-ring 17 for conduction, Ag can be used with the low temperature operation of the battery described later.
The O-ring of Ag softens at the operating temperature of the solid oxide fuel cell to improve the contact resistance. The sealing O-ring 18 is made of aluminosilicate glass (for example, Al ₂ O ₃ 15 to 20%, SiO ₂ 60 to 70%) for the same reason as above. The aluminosilicate glass, which is the O-ring 18 for sealing, melts and seals the porous anode 14 and the substrate 11. The softening and melting temperature of aluminosilicate glass can be adjusted by selecting the composition. The O-ring 17 for conduction and the O-ring 18 for sealing can be used in arbitrary numbers as necessary. When the Ag O-ring is surrounded by the sealing glass as shown in the figure, the deterioration of Ag is prevented in both the oxidizing and reducing high temperature gas atmospheres which are the reaction gas, and the electrical conductivity between the single cell / substrate assembly is reduced. Physical contact is stabilized. Further, the electrode or the tapered tube which is in contact with the O-ring of Ag is prevented from being deteriorated in the oxidizing gas or the reducing high temperature gas atmosphere which is the reaction gas.

A cathode 12 made of lanthanum manganite LaMnO ₃ is formed on the entire outer circumference of the base body, a solid electrolyte body 13 made of yttria-stabilized zirconia YSZ, and an anode 14 made of nickel-zirconia Ni-ZrO ₂ cermet. Stacked. The large diameter end of the substrate is covered with a solid electrolyte body and sealed. In addition, instead of the solid electrolyte body, an aluminosilicate glass may be used for the sealing treatment.

In addition to the heat-resistant alloy, lanthanum manganite LaMnO ₃ , which is a ceramic, can be used for the substrate.
When using lanthanum manganite LaMnO ₃ , the cathode can be omitted. Further nickel-zirconia Ni
-ZrO ₂ cermet can also be used. In this case, the anode is omitted and the solid electrolyte body 13 and the cathode 12 are sequentially laminated.

FIG. 3 shows a manufacturing process of a unit cell / substrate assembly of a solid oxide fuel cell according to an embodiment of the present invention, FIG. 3 (a) is a sectional view showing a taper tube, and FIG. 3 (b) is FIG. 3C is a cross-sectional view showing a base body on which a cathode is formed, and FIG. 3C is a cross-sectional view showing a base body on which a solid electrolyte body is formed on the cathode.
(D) is a cross-sectional view showing a substrate having an anode formed on a solid electrolyte body.

The unit cell / substrate assembly is manufactured as follows. A tube prepared by powder metallurgy is precision processed into a tapered shape to prepare a porous thick taper tube made of a heat resistant alloy having a low coefficient of thermal expansion. The cathode is applied to the obtained tapered tube 11 by the dip method. The coating liquid was prepared by dispersing powder of lanthanum manganite LaMnO _{3 in} a solvent.
The applied cathode is fired at a temperature of 1100 to 1200 ° C. in a reducing atmosphere with an oxygen partial pressure of about 10 ^-1 Pa.
Then, the solid electrolyte body 13 made of yttria-stabilized zirconia YSZ is densely laminated by the plasma spraying method.
Plasma spraying was performed in Ar-He plasma gas under reduced pressure while rotating the sample around the central axis. Single cell /
A solid electrolyte body made of yttria-stabilized zirconia YSZ is also sprayed on the wide end of the base assembly. Subsequently, an anode is applied using a coating solution in which a powder of nickel-zirconia Ni-ZrO ₂ cermet is dispersed in a solvent, and is baked to form an anode 14 to form a single cell / substrate assembly. The firing of the anode is similar to that of the cathode.

The solid electrolyte body 13 can also be formed by the dip method. Although the cathode is formed on the tapered tube in the above process, the anode may be formed instead of the cathode. In this case, the stacking order is reversed. The unit cell / substrate assembly is a unit that constitutes a solid oxide fuel cell stack, and as described above, it is possible to efficiently produce one having a high structural mechanical uniformity. Structural mechanical uniformity improves the stability of the single cell / substrate assembly during heat cycling. Further, the base body which is a tapered tube can be made small, and the solid electrolyte body laminated on the base body has a high uniformity of the film thickness, and a thinner one than the conventional one can be obtained. The thin solid electrolyte allows the battery to operate at a relatively low temperature of 750
To 850 ° C. In this case, a heat-resistant metal material can be used as the structural material of the solid oxide fuel cell, and combined with the structural mechanical stability of the single cell / substrate assembly during the heat cycle described above, Improves reliability.

Further, as the operating temperature is lowered, the range of selection of the battery constituent material is widened, as described in the case of the interconnector. Further, the spring material has an advantage that silicon nitride or the like can be used. FIG. 4 is a sectional view showing a stack of a solid oxide fuel cell according to an embodiment of the present invention together with a housing. The cover 24, the container 25, and the cover 26 form a housing. This housing supports and fixes the stack of the fuel cell, and introduces the oxidant gas and the fuel gas into the stack separately. The cover 24 and the container 25 and the container 25 and the cover 26 are respectively the terminal plates 32.
And 31 through. A partition plate 27 is provided, and the tip thereof serves as a terminal plate 32. A partition plate 28 is provided, and its tip is connected to the terminal plate 31 via a bellows 45. The terminal plate 31 and the terminal plate 32 are insulated from the housing by the gasket 29 and the gasket 30, respectively. The partition wall plate 27 is a dense conductor and has Al 2 to 6% and Cr 15 to 2
It is a 1% Ni-based ferritic steel alloy. Partition plate 28
Is a porous conductor and a similar alloy is used.

A plurality of single cell / base assembly 16 are fitted together, and are further supported and fixed to partition plate 27 together with partition plate 28 by tie bolts 20. Tie bolt 20 for stack
It is hung on the upper part through the nut 22 and the disc spring 23. The partition plate 28 can be vertically displaced via the bellows 45. The guide bush 21 determines the position of the stack and further performs gas sealing. The guide bush 21 is an insulator. The insulator 33 is the tie bolt 20 and the partition plate 2.
7. Insulate. Tie bolt 20 is Al 2-6%, C
A Ni-based ferritic steel alloy with r15-21% is used. Besides, alumina, YSZ or partially stabilized zirconia PSZ can also be used. The disc spring 23 is made of silicon nitride. The stack is free to undergo thermal expansion / contraction in the vertical direction, and the difference in thermal expansion / contraction with the tie bolt 20 is absorbed by the disc spring 23.

The air introduced from the air inlet 36 is introduced into the tie bolt 20 through the gas introduction hole 34 formed in the upper portion of the tie bolt 20, flows through the inside of the stack, and is discharged through the gas discharge hole 35. On the other hand, the fuel gas is the fuel gas inlet 37
It flows in through the outside of the stack, diffuses through the partition plate 28, is mixed with the exhaust air and reacts to become water, and the exhaust gas outlet 3
8 is sent.

The substrate 11 of the stack is electrically connected to the partition plate 27. The potential of the cathode is taken out by the terminal plate 32 via the partition plate 27. The anode 14 is connected to the partition plate 28. The potential of the cathode is taken out to the terminal plate 31 via the partition plate 28 and the bellows 45. FIG. 5 is a sectional view showing a stack of a solid oxide fuel cell according to another embodiment of the present invention together with a housing. This solid oxide fuel cell is provided with a fuel gas outlet 40 and an air outlet 39, and the fuel gas and the oxidant gas are individually discharged.

[0021]

According to the present invention, there is provided a taper tube type solid oxide fuel cell, which comprises (1) a single cell / substrate assembly.
(2) Including a housing, the substrate is a thick porous taper tube, and a single cell is laminated on the entire circumference of a predetermined outer surface. In the single cell, a solid electrolyte body is sandwiched between a cathode and an anode, A plurality of single cell / base assemblies are fitted to each other through an interconnector to form a stack, and a housing supports and fixes the stack, and an oxidant gas and a fuel gas are provided inside and outside the stack. Since the individual cells are made to flow individually, the unit cell / substrate assembly, which is a unit of the solid oxide fuel cell stack, is constructed with a thick substrate as a support, and has a high mechanical strength. Is obtained. Single cell /
The base body of the base body assembly is easy to machine and, together with the interconnector, improves the mechanical and electrical connection between the single cell / base body assembly. Further, in the unit cell / substrate assembly, the thickness of the solid electrolyte body can be made thin, and the operating temperature of the battery can be set to a lower temperature than the conventional one. As a result, a heat-resistant metal can be used, and a solid oxide fuel cell having excellent heat cycle resistance can be obtained in combination with the structural mechanical uniformity of the single cell / substrate assembly.

[Brief description of drawings]

FIG. 1 is a sectional view showing a unit cell / base assembly of a solid oxide fuel cell according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing an interconnector of a solid oxide fuel cell according to an embodiment of the present invention together with a main part of a single cell / base assembly.

FIG. 3 shows a manufacturing process of a unit cell / substrate assembly of a solid oxide fuel cell according to an embodiment of the present invention, FIG. 3 (a) is a sectional view showing a taper tube, and FIG. 3 (b) shows a cathode. Sectional view showing the formed substrate, FIG. 3 (c) is a sectional view showing a substrate having a solid electrolyte body formed on a cathode, and FIG. 3 (d) is a sectional view showing a substrate having an anode formed on the solid electrolyte body. Figure

FIG. 4 is a cross-sectional view showing a stack of a solid oxide fuel cell according to an embodiment of the present invention together with a housing.

FIG. 5 is a sectional view showing a stack of a solid oxide fuel cell according to another embodiment of the present invention together with a housing.

FIG. 6 is a sectional view showing a conventional taper tube type solid oxide fuel cell.

[Explanation of symbols]

 11 Base 12 Cathode 13 Solid Electrolyte 14 Anode 15 Single Cell 16 Single Cell / Substrate Assembly 17 O-ring for Conducting 18 O-ring for Sealing 19 Interconnector 20 Tie Bolt 21 Guide Bush 22 Nut 23 Disc Spring 24 Cover 25 Container 26 cover 27 partition plate 28 partition plate 29 gasket 30 gasket 31 terminal plate 32 terminal plate 33 insulator 34 gas introduction hole 35 gas discharge hole 36 air inlet 37 fuel gas inlet 38 exhaust gas outlet 39 air outlet 40 fuel gas outlet 41 solid electrolyte body 42 Anode 43 Cathode 44 Interconnector 45 Bellows

Claims (12)

[Claims] 1. A taper tube type solid oxide fuel cell, comprising: (1) a unit cell / base assembly, and (2) a housing, wherein the base is a thick porous taper tube. A single cell is laminated around a predetermined outer surface, and a solid electrolyte body is sandwiched between a cathode and an anode in the single cell, and a plurality of the single cell / base body assembly are mutually fitted and stacked through an interconnector. The solid electrolyte fuel cell is characterized in that the casing supports and fixes the stack, and allows the oxidant gas and the fuel gas to individually flow through the inside and the outside of the stack. 2. The solid oxide fuel cell according to claim 1, wherein the substrate is a heat-resistant alloy having a low coefficient of thermal expansion. 3. The solid oxide fuel cell according to claim 2, wherein the heat-resistant alloy having a low coefficient of thermal expansion contains Mo in an amount of 20 to 30.
%, A Ni-based alloy containing 7 to 12% of Cr or a Ni-based alloy containing 20 to 30% of W and 7 to 12% of Cr, a solid oxide fuel cell. 4. The solid oxide fuel cell according to claim 1, wherein the interconnector has an O-ring for conduction and an O-ring for sealing.
A solid oxide fuel cell comprising a ring. 5. The solid oxide fuel cell according to claim 4, wherein the conducting O-ring is an Ag O-ring. 6. The solid oxide fuel cell according to claim 4, wherein the O-ring for sealing is an aluminosilicate glass O-ring. 7. The solid electrolyte fuel cell according to claim 1, wherein the supporting and fixing of the stack is performed through a tie bolt passing through the center of the stack and a spring and a nut provided at one end of the tie bolt. Type fuel cell. 8. The solid oxide fuel cell according to claim 7, wherein the spring is a disc spring made of silicon nitride. 9. The solid oxide fuel cell according to claim 7, wherein the tie bolt is ferritic stainless steel. 10. The solid oxide fuel cell according to claim 9, wherein the ferritic stainless steel contains 2 to 6 Al.
%, Cr is a Ni-based alloy containing 15 to 21%, and a solid oxide fuel cell. 11. The solid oxide fuel cell according to claim 1, wherein an end of the substrate is sealed with a dense solid electrolyte body. 12. The solid oxide fuel cell according to claim 1, wherein the end of the substrate is sealed with aluminosilicate glass.