JP3389469B2 - Solid oxide fuel cell - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bottomed cylindrical solid oxide fuel cell.

[0002]

2. Description of the Related Art Conventionally, a solid electrolyte fuel cell has a high operating efficiency of 900 to 1050 ° C. and thus has high power generation efficiency, and is expected as a third generation power generation system.

Generally, a solid oxide fuel cell has
A cylindrical type and a flat type are known. The flat plate type fuel cell has a feature that the power density per unit volume of power generation is high, but when it is put into practical use, there are problems such as incomplete gas sealing and nonuniform temperature distribution in the cell. On the other hand, the cylindrical fuel cell has the characteristics that although the power density is low, the mechanical strength of the cell is high and the temperature uniformity of the cell can be maintained.

Both types of solid oxide fuel cell unit,
Research and development is being actively promoted by making the most of each characteristic.

As shown in FIG. 3, the unit cell of the cylindrical fuel cell has a porous air electrode 1 made of LaMnO ₃ system material.
And a solid electrolyte ₂ made of partially stabilized Y ₂ O ₃ ZrO 2 is coated on the surface thereof, and a porous Ni-zirconia fuel electrode 3 is further provided on this surface. In the fuel cell module, each single cell is connected via a LaCrO ₃ -based current collector (interconnector) 4.
Power generation is performed at a temperature of 900 to 1050 ° C. by flowing air (oxygen) 6 inside the cylinder and fuel (hydrogen) 7 outside.

The LaMnO ₃ type material, which is an air electrode material, functions as a support tube for the cell.

As an air electrode having a function as a supporting tube, a LaMnO ₃ solid solution material in which La is replaced by 20 atomic% with Ca or 10-15 atomic% with Si is used.

As a method for producing the fuel cell as described above, an insulating powder made of LaMnO ₃ type material is formed into a cylindrical shape by an extrusion molding method or the like, and is then fired to form a support made of a cylindrical air electrode. Of the solid electrolyte, the fuel electrode, and the current collector are applied to the outer peripheral surface of the cylindrical air electrode support and sequentially sintered to be laminated, or the surface of the cylindrical air electrode support is subjected to electrochemical treatment. A solid electrolyte, a fuel electrode, and a current collector are sequentially formed by a dynamic vapor deposition method (EDV method), a plasma spraying method, or the like.

Recently, in order to simplify the cell manufacturing process, a co-sintering method has been proposed in which at least two of the constituent materials are fired in the same manner. In this co-sintering method, for example, a solid electrolyte molded body and a current collector molded body are wound around a molded body of a cylindrical air electrode support tube in a roll shape and simultaneously fired, and then a fuel electrode layer is formed on the solid electrolyte surface. Is the way. This co-sintering method is advantageous in improving the yield in manufacturing cells and reducing costs because the number of manufacturing steps is reduced.

Conventionally, for sealing one end of a cell, a cylindrical cell body obtained by sintering is set on a mounting member in a furnace for actually generating electricity, and a glass layer formed on the mounting member is attached. The glass layer was brought into contact with one end of the cell body and melted at the time of temperature rise during power generation, and one end of the cell body was sealed by the mounting member.

Further, a bottomed tubular sealing member molded body is produced from the air electrode molded body and the same material as the air electrode molded body,
After one end of the air electrode molded body and one end of the sealing member molded body are brought into contact with each other and baked, as described above, the electrochemical vapor deposition method (EDV) is used.
Method) or plasma spraying method to form a dense ceramic layer on the surface of the sealing member to prevent gas leakage from the sealing member.

[0012]

However, in the conventional method in which one end of the fuel cell is sealed with a mounting member using a glass material, sealing is performed when power is actually generated. It is difficult to confirm whether or not it has been stopped, and the output of the single cell is likely to decrease due to defective sealing.In particular, when stacking, the probability of defective sealing increases due to an increase in the number of sealing points. There was a problem that the output decreased.

Further, in the method of firing in a state where one end of the air electrode molded body and one end of the sealing member molded body are in contact with each other, it is difficult to join the air electrode molded body and the sealing member, and moreover, gas leak is caused. In order to prevent this, it is necessary to form a dense ceramic layer on the surface of the sealing member by an electrochemical vapor deposition method (EDV method), a plasma spraying method, etc., and the sealing step is troublesome.
There was a problem of high cost.

An object of the present invention is to provide a solid oxide fuel cell unit in which gas sealing of the cell body can be easily and surely performed and the gas sealing can be easily confirmed.

[0015]

As a result of repeated studies on the above problems, the present inventor found that the outer peripheral surface of one end of the cell body was
The ceramic molded body for the sealing member is externally fitted and fired, and the one end of the cell body is easily and surely sealed by fitting the ceramic molded body for the sealing member to one end of the cell body due to the firing shrinkage of the sealing member. The present invention has been completed by discovering that the sealed state can be easily confirmed.

That is, in the solid oxide fuel cell of the present invention, the air electrode is formed on one surface of the cylindrical solid electrolyte and the fuel electrode is formed on the other surface, and the solid electrolyte fuel cell is electrically connected to the air electrode or the fuel electrode. is, and the one end portion outer peripheral surface of a cylindrical cell body having a collector which is exposed to the outer surface, comprising a ceramic sealing member made from the base portion and the cylindrical portion fitted around the solid
A fuel cell for an electrolyte type fuel cell, comprising:
Due to the contraction, the cylindrical portion of the sealing member becomes an end portion of the cell body.
While tightening, seal the cell body at one end.
A member is externally fitted, the total length of the sealing member is L ₁ , the depth of the cylindrical portion is L ₂ , the outer diameter of the base portion is D ₁ , the outer diameter of the cylindrical portion is D ₂ , and the cylinder is When the inner diameter of the part is D ₃ , D
₁ / D ₂ is 0.78~0.84, L ₂ / L ₁ is 0.3 to 0.
7, L ₂ / D ₃ is one which satisfies the range of 0.3 to 0.7. Here, it is desirable that a sealing member is externally fitted to the outer peripheral surface of one end of the cell body with a gas sealing layer made of ceramics interposed therebetween.

[0017]

In the solid oxide fuel cell of the present invention, unlike the conventional case, one end of the cell main body is not sealed by a mounting member when the power generation cell main body is set in a furnace to generate electric power, Since one end of the cell body is sealed with dense ceramics at the manufacturing stage, one end of the cell body can be easily and surely sealed, and the cell body for power generation is sealed before being set in the furnace. You can check
The gas sealability during power generation is sufficiently guaranteed.

That is, in the solid oxide fuel cell of the present invention, the ceramics for a sealing member is formed by externally fitting and firing the ceramics molding for a sealing member on the outer peripheral surface of one end of the cell body. When the total length of the sealing member is L ₁ , the depth of the cylindrical portion is L ₂ , the outer diameter of the base portion is D ₁ , the outer diameter of the cylindrical portion is D ₂ , and the inner diameter of the cylindrical portion is D _3. , D ₁ /
D ₂ is 0.78 to 0.84 and L ₂ / L ₁ is 0.3 to 0.
7, L ₂ / D ₃ is one which satisfies the range of 0.3 to 0.7.

At the same time that the cylindrical portion of the sealing member is fitted to one end of the cell body, the outer surface of the cell body and the inner surface of the sealing member cylinder portion are connected at the same time during firing, so that one end of the cell body is sealed. It can be done easily and reliably. Further, the tip end surface of the cell body and the inner bottom surface of the base portion of the sealing member adhere to each other, whereby the sealing member can be firmly fixed to the cell body.

Particularly, in the solid oxide fuel cell of the present invention, ceramic slurry is applied to the outer peripheral surface of one end of the cell body to form a gas seal layer made of ceramics, and a sealing member is fitted to the outer peripheral surface. By doing so, even if the outer surface of the cell body is uneven due to the current collector protruding from the cell body, the outer surface of the cell body where the sealing member is fitted by the gas seal layer is flat. The sealing member and the cell body can be brought into close contact with each other without a gap, and the gas sealability can be improved.

Further, according to the present invention, for example, when a ZrO ₂ or LaCrO ₃ system porcelain is used as the sealing member, the firing temperature (1300 ° C. or higher) of this porcelain is the actual power generation temperature (1000 ° C.). ) Is higher, there is no fear of gas leakage during power generation, and as a result, reliability of cell output and longer life can be achieved. Furthermore, when assembling a stack using a plurality of cells, it is possible to simplify the system design because it is possible to minimize the number of sealing points at the stage of power generation.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION In the cell body of the present invention, a solid electrolyte is formed on the surface of a cylindrical air electrode, a fuel electrode is formed on the surface of this solid electrolyte, and the cell body is electrically connected to the air electrode. A cell body is formed by providing a current collector.

As shown in FIG. 1, a gas seal layer 9 made of ceramics is formed on the outer peripheral surface of one end of the cell body 8, and the gas seal layer 9 is formed on the surface of the gas seal layer 9. A cap-shaped sealing member 11 made of dense ceramics is externally fitted, and the cell body 8, the gas seal layer 9, and the sealing member 11 are integrated by firing. That is, by applying a ceramics slurry to the outer peripheral surface of one end of the cell body 8 to eliminate the irregularities on the outer peripheral surface of the cell body 8 and to flatten the surface, and then by externally fitting and firing the ceramic molded body for a sealing member. , The ceramics for the sealing member will shrink by firing,
At the same time as being fitted to one end of the cell body 8, the outer peripheral surface of the cell body 8 and the inner surface of the sealing member 11 are joined via the gas seal layer 9 during firing.

The gas seal layer 9 may be, for example, a partially stabilized Z
Various materials such as rO ₂ , stabilized ZrO ₂ and LaCrO ₃ can be used, but it is particularly preferable to use the same material as the solid electrolyte material from the viewpoint of the coefficient of thermal expansion. The thickness of the gas seal layer 9 may be such that the outer surface of the cell body 8 is not uneven, but is preferably 50 to 300 μm.

The sealing member 11 is made of dense ceramics in order to prevent gas leakage. As the dense ceramics, for example, the same material as the gas seal layer 9 can be used. Also, like the gas seal layer 9,
From the viewpoint of the coefficient of thermal expansion, it is desirable to use the same material as the solid electrolyte material. In the case of Y ₂ O ₃ partially stabilized ZrO ₂ , the coefficient of thermal expansion of the sealing member 11 and the gas seal layer 9 can be adjusted by changing the ratio of Y ₂ O ₃ and ZrO ₂ .

The sealing member 11 is composed of a cylindrical portion 13 into which the cell body 8 is inserted and a base portion 14. Here, the total length of the sealing member 11 is L ₁ , and the depth of the cylindrical portion 13 is L ₁ .
₂ , when the outer diameter of the base portion 14 is D ₁ , the outer diameter of the cylindrical portion 13 is D ₂ , and the inner diameter of the cylindrical portion 13 is D ₃ , D ₁ / D ₂ is 0.78 to 0.84, L ₂ / L ₁ is 0.3 to 0.7, L
₂ / D ₃ satisfies the range of 0.3 to 0.7.

[0027] The ratio between the outer diameter D ₂ of the outer diameter D ₁ and the cylindrical portion 13 of the base portion 14 (D ₁ / D ₂₎ and 0.78 to 0.84, the cell body if within this range Sealing member 1 on the outer surface of 8
This is because the sample No. 1 is closely fixed and no gas leaks. D ₁ /
This is because when D ₂ is smaller than 0.78, a crack is generated between the cylindrical portion 13 and the base portion 14 and it is damaged in the reduction treatment test of the fuel cell, and when it is larger than 0.84. ． This is because the tightening force of the cell body 8 by the cylindrical portion 13 is weak, and gas may leak from between the cell body 8 and the cylindrical portion 13. The value of D ₁ / D ₂ is 0.80 to 0.82 from the viewpoint of improving the gas sealing property and preventing the sealing member 11 from being damaged, and being excellent in the high temperature load test and the cycle test. Is desirable.

The ratio (L ₂ / L ₁ ) between the total length L ₁ of the sealing member 11 and the depth L ₂ of the cylindrical portion 13 is set to 0.3 to 0.7 because the ratio is 0.3. This is because if it is too small, it will be damaged in the reduction process of the fuel cell, and because the ceramic molded body 31 for a sealing member will not be stable when it is inserted into the cell body 8. This is because the stopper member molded body 31 cannot be stably inserted into one end of the cell body 8. On the other hand, L ₂ / L ₁ is 0.7
If it is larger than the above range, the formation area of the fuel electrode becomes small and the power generation capacity decreases.

The ratio (L ₂ / D ₃ ) between the depth L ₂ of the cylindrical portion 13 and the inner diameter D ₃ of the cylindrical portion 13 is 0.3 to 0.7.
This is because if L ₂ / D ₃ is smaller than 0.3, it will be damaged during the reduction treatment of the fuel cell, and further, it will not be stable when the ceramic molded body 31 for a sealing member is inserted into the cell body. This is because the molded body 31 for a sealing member cannot be stably inserted into one end of the cell body 8 when the cell body 8 is laid down sideways. On the other hand, L ₂ / D ₃ is 0.
This is because if it is larger than 7, the formation area of the fuel electrode becomes small and the power generation capacity is reduced. Further, it is difficult to cut the sealing member molded body 31 and the sealing member molded body 31 is easily damaged during storage.

That is, L ₂ / L ₁ and L ₂ / D ₃ are set to 0.
The reason why the number is 3 or more is as follows. As for the posture of the cell body in which the molded body for the sealing member is inserted, during firing, it is safer to lay it sideways rather than to erect a long cylinder.
In that case, the molded body 31 for the sealing member is the cell body 8 which is laid sideways.
It must have a shape that is sufficiently stable even if it is inserted into one end of the.
In addition, the tip surface of the cell body 8 and the cylindrical portion 13 of the sealing member 11
If the inner bottom surface of the cell is insufficiently contacted, the cell body 8 and the sealing member 11 may not be completely integrated after firing, and the adhesion between the cell body 8 and the sealing member 11 may be broken. Even if the cell is in a horizontal position, the inner diameter D ₃ of the cylindrical portion 13 of the sealing member 11 after sintering is required so that the sealing member molded body 31 inserted before sintering is stably at one end. The depth L ₂ of the cylindrical portion 13 of the sealing member 11 is 30% or more,
Depth L of the cylindrical portion 13 of the sealing member 11 with respect to the total length L ₁ of
_{This is because 2} needs to be 30% or more.

In view of stability when the cell body 8 is inserted into the sealing member 11, L ₂ / L ₁ is preferably 0.4 or more and L ₂ / D ₃ is 0.4 or more. Also, the manufacturing time of the ease of the sealing member molded articles 31, L ₂ / L ₁ is 0.6 or less, L ₂ /
D ₃ is preferably 0.6 or less.

The thickness t of the cylindrical portion 13 of the sealing member 11 that abuts on the outer surface of the cell body 8 is to prevent the cell diameter from increasing and prevent the cell from being damaged by the contraction stress during sintering. , 0.3 to 1.2 mm is desirable.

A method of manufacturing such a solid oxide fuel cell will be described in detail. First, in order to manufacture a cell body, a cylindrical air electrode molded body having a function as a self-supporting tube is manufactured by extrusion molding, and thereafter 1200 to
Debinding and calcination are performed at a temperature of 1300 ° C. for about 5 to 20 hours to prepare an air electrode calcined body. This air electrode calcined body is composed of LaCr containing a perovskite type crystal phase as a main phase.
It is an O ₃ -based material, and its average crystal grain size is preferably 2 to 30 μm, particularly 5 to 15 μm. This is because if the particle size of the main crystal phase is smaller than 2 μm, the strength is high but the gas permeability is low, and if it exceeds 30 μm, the gas permeability is high but the strength is insufficient. The open porosity of the air electrode is preferably 20 to 45%, particularly 30 to 40%. Moreover, the gas permeability is excellent when the average pore diameter is in the range of 1.0 to 5.0 μm.

Next, a compact layer of a material forming the solid electrolyte is formed on the surface of the air electrode calcined body.

The solid electrolyte molded body layer is prepared by preparing a slurry by using a powder made of ZrO ₂ stabilized by a known stabilizer such as Y ₂ O ₃ having an average particle diameter of 0.5 to 3 μm. Then, it is formed by winding a green sheet produced by a doctor blade method or the like.

Then, the air electrode / solid electrolyte molded body was replaced with 10
Calcination is performed at a temperature of 00 to 1300 ° C. for about 1 to 3 hours, and then the surface of the solid electrolyte calcined body, which is the laminated portion of the current collector, is smoothed to expose the air electrode calcined body, A current collector molded body is laminated on the surfaces of the fired body and the air electrode calcined body. The current collector molded body uses a LaCrO ₃ type material,
It is formed by stacking green sheets similarly to the solid electrolyte molded body.

The laminated body produced in this manner is 3-1 at a temperature of 1300 to 1600 ° C. in an oxidizing atmosphere such as air.
Co-sintering is performed by co-firing for about 5 hours to produce a cylindrical cell body 8.

Further, the fuel electrode is made of a porous cermet material containing 30 to 80% by weight of Ni and the balance being stabilized ZrO ₂ (including a stabilizing agent such as Y ₂ O ₃ ). Forming a compact at a predetermined place on the body and sintering,
Alternatively, after forming the air electrode / solid electrolyte / current collector formed body, a fuel electrode formed body is further laminated and these are fired at the same time, so that the cylindrical cell body 8 can be produced.

Next, for example, using the same slurry as the solid electrolyte molded body, for example, by dipping one end of the cell body 8 in the slurry, an outer surface of the one end of the cell body 8 is formed. Apply ceramic slurry,
Dry at 100-150 ° C for 1-3 hours. Other methods for applying the ceramics slurry include application by spraying or brush. It is desirable that the ceramics slurry is applied in a slightly larger area than the portion where the sealing member is fitted. Regarding the coating thickness, the cell body 8
There is no particular limitation as long as there is no unevenness on the outer peripheral surface. In the present invention, such a ceramic slurry coating step (gas seal layer) is not always necessary, but it is desirable to have a certain point from the viewpoint of more reliable gas seal.

Since the sealing member 11 is required to have a gas sealing property during power generation, for example, the average crystal grain size is 0.5 to 3 μm.
About ZrO ₂ type or LaCrO ₃ type oxide powder is formed by extrusion molding or hydrostatic molding (rubber press),
The cap shape is cut to form the sealing member molded body 31. It is desirable to use yttria partially stabilized zirconia for the gas seal layer and the sealing member.

At this time, the molded body 31 for a sealing member is brought into contact with the outer peripheral surface of the cell body 8 and the cylindrical body 13 to be clamped preferably has a molded body thickness of 0.7 to 2.0 mm. When the thickness is less than 0.7 mm, this is the sealing member 1 during firing.
1 may be broken, and if it is thicker than 2.0 mm, the distance between the cells when making a stack with a plurality of solid oxide fuel cell units becomes large, and electrical connection becomes difficult. Is. Further, since the outer diameter increases by the thickness of the cylindrical portion 13, it is required to reduce the thickness of the cylindrical portion 13 of the sealing member 11 in order to prevent the outer diameter from increasing as much as possible. Yttria partially stabilized zirconia having is desirable.

The inner diameter of the cylindrical portion 33 of the ceramic molded body for a sealing member into which one end of the cell body 8 is inserted is preferably 1.05 to 1.25 times the outer diameter of the cell body 8. This is because the inner diameter of the cylindrical portion 33 is 1.
If it is less than 05 times, cracking is likely to occur in the sealing member 11, and if it is more than 1.25 times, a gap is created between the sealing member 11 and the cell body 8 to allow sealing. This is because it may disappear. Also, the sealing member 1
The size, material, etc. of the sealing member molded body 31 are determined so that the inner diameter of the cylindrical portion 13 when 1 is singly sintered is smaller than the outer diameter of the cell body 8.

Thereafter, as shown in FIG. 2, one end of the cell body 8 is inserted into the cylindrical portion 33 of the molding member 31 for a sealing member,
In an oxidizing atmosphere such as the air, it is baked at a temperature of 1300 to 1600 ° C. for about 1 to 5 hours, and as shown in FIG. 1, the sealing member 11 is provided at one end of the cell body 8 via the gas seal layer 9.
To obtain the solid oxide fuel cell of the present invention.
The posture of the cell body at the time of firing can take a stable posture of being laid down.

The firing temperature of the ceramic molded body for the sealing member is preferably in the range of 1350 to 1500 ° C. That is, after the cell body 8 is sintered, the sealing member 11 is newly formed.
In order to sinter, the sintering temperature of the gas seal layer 9 and the sealing member 11 is required to be lower than the sintering temperature of the cell body 18. For example, a fuel cell or the like using a LaCrO ₃ system material is sintered at about 1500 ° C., but yttria partially stabilized zirconia can be sintered at 1400 ° C., which is lower than that, so that the sealing member 11 and the gas seal are used. Yttria partially stabilized zirconia is preferred for layer 9.

The inner surface of the cylindrical portion 13 of the sealing member 11 and the gas seal layer 9 are integrated during firing, and the gas seal layer 9 and the outer peripheral surface of one end of the cell body 8 are also integrated during firing.
As a result, the inner side surface of the cylindrical portion 13 of the sealing member 11 is joined to the outer peripheral surface of the one end portion of the cell body 8 via the gas seal layer 9. Further, the inner bottom surface of the base portion 14 of the sealing member 8 and the cross section of the cell body 8 are integrated during firing, so that the sealing member 11 and the cell body 8 are firmly fixed. It is sufficient that the gas seal layer 9 and the sealing member 11 made of dense ceramics can prevent gas leakage, and it is particularly preferable that the open porosity is 5% or less.

In the present invention, the fuel electrode slurry is applied to the cell body having the air electrode, the solid electrolyte and the current collector, and then the cell body is inserted into the cylindrical portion of the molded body for the sealing member to form the fuel electrode. You may bake the said molded body for sealing members simultaneously with a coating film, and bake a fuel electrode on the surface of a solid electrolyte. In this case, the pretreatment step for burning only the fuel electrode can be omitted.

[0047]

EXAMPLE In order to manufacture a cylindrical solid oxide fuel cell unit by co-sintering, first, a cylindrical air electrode molded body was manufactured as follows. La with a purity of 99.9% or more on the market
₂ O ₃ , CaCO ₃ , and Mn ₂ O ₃ were used as starting materials, and they were weighed and mixed so as to have a composition of La _0.8 Ca _0.2 MnO ₃ and then calcined at 1500 ° C. for 3 hours and pulverized to obtain an average particle size of A solid solution powder of 5 μm was obtained. Further, a binder was added to this solid solution powder, and a cylindrical air electrode formed body was produced by an extrusion molding method. The air electrode molded body is dried 12
A cylindrical air electrode calcined body was produced by debinding and calcining at 50 ° C. for 10 hours.

Next, 8% of Y ₂ O ₃ obtained by the coprecipitation method was used.
ZrO _{2 with} an average particle size of 1 μm contained in a mol% ratio
Toluene and a binder were added to the powder to prepare a slurry, and a solid electrolyte sheet having a thickness of 130 μm was prepared by the doctor blade method.

Next, commercially available La _{2 having} a purity of 99.9% or more is used.
Using O ₃ , Cr ₂ O ₃ and MgO as starting materials,
A (Mg _0.3 Cr _0.7 ) _0.97 O ₃ was weighed and mixed so as to have a composition, then calcined at 1500 ° C. for 3 hours and pulverized to obtain a solid solution powder having an average particle diameter of 2 μm. Next, toluene and a binder were added to this solid solution powder to prepare a slurry, and a collector sheet having a thickness of 130 μm was prepared by the doctor blade method.

The solid electrolyte sheet was wound around the cylindrical air electrode calcined body in a roll shape and calcined at 1100 ° C. for 3 hours. After calcination, the surface of the solid electrolyte to be the laminated portion of the current collector sheet was flat-polished, the surface was flat-polished to the exposed air electrode calcined body, and the current collector sheet was wound in a strip shape at a predetermined position. . After that, co-sintering was attempted under the conditions of 1500 ° C. for 6 hours in the atmosphere.

After co-sintering, ZrO ₂ (10 m
ol% Y ₂ O ₃ ) powder was mixed at a weight ratio of 80:20 to prepare a fuel electrode slurry by adding water as a solvent to the fuel electrode slurry, and the fuel electrode slurry having a thickness of 50 μm was applied to the surface of the laminated sintered body. After drying, a cell body having an outer diameter of about 15 mm and a thickness of 2 mm was prepared.

Next, water was added as a solvent to ZrO ₂ powder having an average particle size of 1 μm and containing Y ₂ O ₃ at a ratio of 3 mol%, to prepare a slurry, and one end of the cell body was dipped in the slurry. Thickness 1 by crushing and dipping method
A ceramic slurry of 00 μm was applied to the outer peripheral surface of one end of the cell, and dried at 120 ° C. for 1 hour.

Next, a cap-shaped molded body as a sealing member is produced. First, hydrostatic pressure molding (rubber press) was performed using ZrO ₂ powder having an average particle diameter of 1 μm and containing Y ₂ O ₃ at a ratio of 3 mol%, which is the same composition as the slurry composition, to obtain a cap shape. It was cut. After that, the one end of the cell coated with the slurry was inserted into the molding for a sealing member.

The wall thickness t of the cylindrical portion of the molded body for a sealing member that contacts the outer peripheral surface of the cell body and tightens the cell body is 0.7 m.
set to m.

Thereafter, the fuel electrode layer is formed by firing at 1400 ° C. for 2 hours in the atmosphere, and a cap-shaped molding sealing member is formed on the outer peripheral surface of one end of the cell body via a gas sealing layer. Mated The total length of the sealing member L _1, the depth L ₂ of the cylindrical portion, D ₁ the outer diameter of the base portion, the outer diameter of the cylindrical portion D _2, D when the inner diameter of the cylindrical portion and the D _{3 1} /
The values of D ₂ , L ₂ / L ₁ and L ₂ / D ₃ are shown in Table 1.

Air is injected from the open end of the cell body on the non-sealed side by pressurizing Air so that the internal pressure inside the cell body is +1 kgf / cm ² higher than the external pressure. Then, this was submerged in water, and the presence or absence of a leak was judged by the presence or absence of bubbles.

This sample was also tested in an air atmosphere at 1000 ° C.
Left for 100 hours, 500 hours, 10 hours
After 00 hours, it is cooled to room temperature and taken out, and Air is added from the open end on the side where sealing is not performed so that the internal pressure inside the cell body is +1 kgf / cm ² higher than the external pressure. It was injected under pressure, submerged in water, and the presence or absence of leak was judged by the presence or absence of bubbles (high temperature load test). Further, in an air atmosphere, the temperature is raised from room temperature to 1000 ° C. at a temperature rising rate of 200 ° C./h, left for 1 hour, then cooled from 1000 ° C. to room temperature at a temperature lowering rate of 200 ° C./h, and left for 1 hour. After repeating 10 cycles, the presence or absence of leak was judged in the same manner as above.

Further, a reduction treatment test was conducted by leaving the inside of the cell in an Air atmosphere and the outside of the cell in an H ₂ atmosphere at 1000 ° C. for 1 hour to determine whether or not there was a leak. The results are shown in Table 1.

[0059]

[Table 1]

From Table 1, the sample of the present invention can prevent damage due to stress in sintering shrinkage,
It can be seen that there is no leak and no damage in the cycle load test and reduction treatment test.

On the other hand, when L ₂ / L ₁ was smaller than 0.3 or when L ₂ / D ₃ was smaller than 0.3, the sealing member was broken in the reduction treatment test. In detail, the sealing member was damaged and the base part was dislocated while leaving the cylindrical part in the cell body. When a similar sample was recreated and the interface between the inner bottom surface of the sealing member and the cross section of the cell body was observed before carrying out each load test, a gap was observed. These were because the depth of the cylindrical part was not sufficient, and the sealing member was easily displaced during the process from the furnace to the sintering.Therefore, the inner bottom surface of the base of the sealing member and the tip surface of the cell body were It is considered that the fixation due to the reaction of became insufficient.

[0062]

As described in detail above, according to the present invention,
The one end of the cell body can be easily and reliably sealed, and the sealed state can be confirmed before the power generation cell body is set in the furnace, and the gas sealability during power generation is sufficient. Guaranteed and stable cell performance can be maintained over the long term.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a solid oxide fuel cell unit of the present invention.

FIG. 2 is a cross-sectional view in which a molding for a sealing member is inserted into a cell body.

FIG. 3 is a perspective view showing a cell body of a solid oxide fuel cell unit.

[Explanation of symbols]

1 ... Air electrode 2 ... Solid electrolyte 3 ... Fuel electrode 4 ... Current collector 8: Cell body 9 ... Gas seal layer 11 ... Sealing member 13 ... Cylindrical part 14 ... Base

Claims (2)

(57) [Claims] 1. A cylindrical solid electrolyte having an air electrode formed on one surface and a fuel electrode formed on the other surface, and a current collector which is electrically connected to the air electrode or the fuel electrode and is exposed on the outer surface. A cylindrical sealing member made of a base portion and a cylindrical portion is externally fitted to the outer peripheral surface of one end of the cylindrical cell body provided.
A solid oxide fuel cell unit comprising the sealing member
Due to the firing shrinkage of
While tightening one end of the
The sealing member is externally fitted, the total length of the sealing member is L ₁ , the depth of the cylindrical portion is L ₂ , the outer diameter of the base portion is D ₁ , and the outer diameter of the cylindrical portion is D _2. , The inner diameter of the cylindrical portion is D ₃
Then, D ₁ / D ₂ satisfies the ranges of 0.78 to 0.84, L ₂ / L ₁ satisfies the range of 0.3 to 0.7, and L ₂ / D ₃ satisfies the range of 0.3 to 0.7. A solid oxide fuel cell unit characterized by the above. 2. The solid oxide fuel cell according to claim 1, wherein a sealing member is fitted on the outer peripheral surface of one end of the cell body via a gas sealing layer made of ceramics.