JPH11283640A - Cylindrical solid-electrolyte fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cylindrical solid-electrolyte fuel cell such that a cell main body can be easily and surely gas-sealed and the gas seal is easy to check. SOLUTION: An air electrode is formed on one side of a cylindrical solid- electrolyte and a fuel electrode is formed on the other side. A cap-shaped sealing member 11 made of ceramics, which comprises a base bottom part 14 and a cylinder part 13, is fitted over the outer peripheral surface of one end of a cylindrical cell main body 8 via a gas seal layer 9 made of ceramics with a thickness of 70 to 250 μm, the cell main body 8 being electrically connected to the air electrode or the fuel electrode and having a current collector exposed to the outer surface thereof.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a cylindrical solid oxide fuel cell.

[0002]

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

[0003] In general, solid oxide fuel cells include:
A cylindrical type and a flat type are known. The flat-plate type fuel cell has the feature that the power density per unit volume of power generation is high, but there are problems such as imperfect gas sealing and non-uniform temperature distribution in the cell in practical use. On the other hand, the cylindrical fuel cell has a feature that although the output density is low, the mechanical strength of the cell is high and the uniformity of the cell temperature can be maintained.

In both types of solid oxide fuel cells,
Research and development are being actively pursued by taking advantage of each feature.

A cylindrical solid oxide fuel cell is shown in FIG.
As shown in the above, a porous air electrode 2 made of a LaMnO ₃ -based material is formed, and Y ₂ O ₃ partially stabilized Zr
A solid electrolyte 3 made of O ₂ is covered, and a porous Ni-zirconia fuel electrode 4 is provided on this surface. In the fuel cell module, each single cell is LaC
It is connected via an rO ₃ -based current collector (interconnector) 5. 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.

[0006] As a method of producing the above-mentioned fuel cell, a method of extruding an insulating powder made of a LaMnO ₃ -based material into a cylindrical shape by an extrusion molding method or the like, and then calcining this to form a support comprising a cylindrical air electrode. A slurry of a solid electrolyte, a fuel electrode, and a current collector is applied to the outer peripheral surface of the cylindrical air electrode support and sequentially fired and laminated, or the surface of the cylindrical air electrode support is electrochemically coated. In some cases, a solid electrolyte, a fuel electrode, and a current collector are sequentially formed by a selective vapor deposition method (EDV method), a plasma spraying method, or the like.

Recently, a co-sintering method has been proposed in which at least two of the constituent materials are simultaneously fired in order to simplify the cell manufacturing process. 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 surface of the solid electrolyte. Is the way. This co-sintering method is advantageous in improving the yield during cell production and reducing costs since the number of production steps is reduced.

[0008] Conventionally, one end of the cell is sealed by setting a cylindrical cell body obtained by sintering to a mounting member in a furnace for actually generating electric power, and attaching a glass layer formed on the mounting member. The glass layer is melted at the time of temperature rise when power is generated by contacting one end of the cell body, and one end of the cell body is sealed by the mounting member.

[0009] Further, an air electrode molded body and a bottomed cylindrical sealing member molded body made of the same material as the air electrode molded body are produced.
After one end of the air electrode molding and one end of the sealing member molding are brought into contact with each other and fired, the electrochemical vapor deposition method (EDV
Method) or a plasma spraying method, a dense ceramic layer was formed on the surface of the sealing member to prevent gas leakage from the sealing member.

[0010]

However, according to the conventional method of sealing one end of the fuel cell with a mounting member using a glass material, the fuel cell is completely sealed when power is actually generated. It is difficult to confirm whether or not the sealing has been performed, and the output of a single cell is likely to decrease due to sealing failure.In particular, in the case of stacking, the probability of occurrence of sealing failure increases due to an increase in sealing locations, and as a result, 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 furthermore, the gas leakage is reduced. 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, or the like, and the sealing process is troublesome.
There was a problem that the cost was high.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a cylindrical solid oxide fuel cell capable of easily and reliably performing gas sealing of a cell body and easily confirming the gas seal.

[0013]

Means for Solving the Problems As a result of repeated studies on the above problems, the present inventors applied ceramic slurry for a gas sealing layer to the outer peripheral surface of one end of a cell body, and then applied the ceramic slurry for a sealing member. The ceramic molded body is externally fitted and fired, and the sealing member is fitted to one end of the cell main body by firing shrinkage, whereby one end of the cell main body can be easily and reliably sealed. It has been found that the stopped state can be easily confirmed, and the present invention has been achieved.

That is, the solid electrolyte fuel cell of the present invention has an air electrode formed on one side and a fuel electrode formed on the other side of a cylindrical solid electrolyte, and is electrically connected to the air electrode or the fuel electrode. And a thickness of 70 to 25 on the outer peripheral surface of one end of a cylindrical cell body having a current collector exposed on the outer surface.
Through a gas seal layer made of 0 μm ceramic,
A ceramic cap-shaped sealing member consisting of a base portion and a cylindrical portion is externally fitted. Here, the gas sealing layer and the cap-shaped sealing member are made of Z ₂ containing Y ₂ O _3.
Desirably, it is composed of rO ₂ .

Further, the overall length of the sealing member in the axial direction is L ₁ , the outer diameter of the base portion is D ₁ , the axial length of the cylindrical portion is L ₂ , the outer diameter of the cylindrical portion is D ₂ , and the outer diameter of the cylindrical portion is D ₂ . when an inner diameter set to D _3, D ₁ /
D ₂ satisfies the range of 0.78 to 0.84,
L ₂ / L satisfies the range of 0.3 to 0.7, and L ₂ / L
It is desirable that D ₃ satisfies the range of 0.3 to 0.7.

[0016]

The cylindrical solid oxide fuel cell according to the present invention comprises:
Instead of sealing one end of the cell body with a mounting member when setting the cell body in a furnace and performing power generation as in the past, one end of the cell body is sealed with dense ceramics at the cell manufacturing stage. In addition to being able to easily and reliably seal one end of the cell body, it is possible to check the sealing state before setting the power generation cell body in the furnace,
Gas sealing performance when power generation is continued is sufficiently ensured.

That is, the cylindrical portion of the sealing member is fitted to one end of the cell body via the gas seal layer, and at the same time, the outer surface of the cell body and the inner surface of the sealing member cylindrical portion are joined at the time of firing. One end of the cell body can be easily and reliably sealed. In addition, the sealing member can be firmly fixed to the cell body by joining the end surface of the cell body and the inner bottom surface of the base of the sealing member.

Further, when assembling a stack using a plurality of cells, the number of sealing portions at the stage of generating power can be reduced as much as possible, thereby facilitating system design.

Then, a ceramic cap-shaped sealing member consisting of a base portion and a cylindrical portion was fitted over the outer peripheral surface of one end of the cell body via a gas seal layer made of ceramic having a thickness of 70 to 250 μm. In the power generation, there is no gas leak for a long time, the reliability can be improved, and the size of the cell body in the diameter direction can be prevented from increasing.

That is, a plurality of portions such as a solid electrolyte and a current collector are present on the surface of a cylindrical solid oxide fuel cell, and a boundary between these portions is several tens of thickness of each portion. Although there is a step of about one hundred and several tens μm,
The gas seal layer made of 250 μm ceramic eliminates the gap between the cell body and the sealing member due to the step,
The occurrence of gas leak can be prevented.

Further, according to the present invention, for example, when a ZrO ₂ or LaCrO ₃ porcelain is used as a gas seal layer or a sealing member, the firing temperature of the porcelain (1300 ° C. or higher) is set to the actual power generation. Higher than the temperature (1000 ° C)
There is no fear of gas leak during power generation, and as a result, reliability of output and longer life can be achieved.

Further, the posture of the cell body when sintering the molded body of the sealing member is more stable when the cell body is turned sideways than when the long cylindrical cell body is erected. In this case, the molded body of the sealing member needs to have a shape that is sufficiently stable even when inserted into one end of the cell body that is turned over. Also, if the contact between the end surface of the cell body and the inner bottom surface of the base of the sealing member is insufficient, the integration of the cell body and the sealing member after firing becomes incomplete, and the connection between the cell body and the sealing member becomes incomplete. There is a fear that the joint will be destroyed. In the present invention, the length L ₂ of the cylindrical portion of the sealing member is set to _{3 with} respect to the inner diameter D ₃ of the cylindrical portion of the sealing member after sintering.
0% or more, in the axial direction of the cylindrical portion of the sealing member relative to the total axial length L ₁ of the sealing member after sintering the length L ₂ 3
Since it is 0% or more, the sealing member inserted into the cell main body can be bonded in a stable state even when the cell main body is lying down.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION A cell body of a cylindrical solid oxide fuel cell according to the present invention has, for example, a structure in which a solid electrolyte is formed on the surface of a cylindrical air electrode, and a fuel electrode is formed on the surface of the solid electrolyte. Further, a current collector electrically connected to the air electrode is provided to form the cell body.

As shown in FIGS. 1 and 2, a gas seal layer 9 made of ceramic is formed on the outer peripheral surface of one end of the cell body 8. A sealing member 11 made of a dense ceramic having a cap shape 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 ceramic slurry to the outer peripheral surface of one end of the cell main body 8, the outer peripheral surface of the cell main body 8 is eliminated and flattened, and then the ceramic molded body for a sealing member is fitted and fired. As a result, the ceramic for the sealing member shrinks by firing, and is fitted to one end of the cell body 8, and at the same time, the outer peripheral surface of the cell body 8 and the inner surface of the sealing member 11 are interposed via the gas seal layer 9 during firing. Are joined. Note that the sealing member 11 includes a cylindrical portion 13 and a base portion 14.

The gas seal layer 9 is made of, 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.

On the surface of the cell body 8, a step of about 80 to 150 μm is formed at the boundary between the solid electrolyte and the current collector. By flattening the steps, gas leakage can be prevented stably at a high temperature in an atmosphere in a power generation state. When the gas seal layer 9 is formed, if the thickness is large, the gas seal layer 9 is easily damaged during the formation process, or the thickness of the formed gas seal tank becomes non-uniform, and cracks occur during firing or heating during power generation. Is generated, gas leaks are likely to occur, and the diameter of the sealing member 11 portion of the cylindrical solid electrolyte fuel cell increases, so that the interval when connecting the cylindrical solid electrolyte fuel cells is reduced. The size of the fuel cell increases and the size of the fuel cell increases.

To stably prevent the occurrence of gas leak, stably form the gas seal layer 9 in the process of manufacturing a cylindrical solid oxide fuel cell, and suppress the increase in diameter,
The thickness d of the gas seal layer 9 needs to be in the range of 70 to 250 μm. Particularly, the thickness d of the gas seal layer 9 is 80 to
It is desirable to be in the range of 200 μm.

That is, the gas seal layer 9 is formed by applying a ceramic slurry. However, when the thickness is increased, the gas seal layer 9 is easily broken during the formation process, and the diameter of the cylindrical solid oxide fuel cell increases. Therefore, the average thickness of the gas seal layer 9 is set to 250 μm or less. In particular, it is desirable that the average thickness of the gas seal layer 9 be 200 μm or less.

The sealing member 11 is made of dense ceramics in order to prevent gas leakage. The dense ceramics may be, for example, the same material as the gas seal layer 9. Further, similarly to the gas seal layer 9,
From the viewpoint of the coefficient of thermal expansion, it is desirable to be made of 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 to ZrO ₂ .

The thickness t of the cylindrical portion 13 of the sealing member 11 which is in contact with the outer surface of the cell body 8 is such that the increase in the diameter of the cell is suppressed and the cylindrical solid electrolyte type To prevent damage to the end of the fuel cell,
1.2 mm or less is desirable.

The thickness t of the sealing member 11 is 0.3 m in order to prevent the sealing member 11 from being damaged by shrinkage stress during sintering.
m or more is desirable.

A method for manufacturing such a cylindrical solid oxide fuel cell will be described in detail. First, in order to produce a cell body, a cylindrical air electrode molded body having a function as a self-supporting tube is produced by extrusion molding, and thereafter, a 12
Binder removal and calcination are performed at a temperature of 00 to 1300 ° C. for about 5 to 20 hours to prepare a cathode calcined body.

Next, a molded layer of a material constituting the solid electrolyte is formed on the surface of the calcined cathode.

A slurry is prepared by using a powder of ZrO ₂ stabilized with a known stabilizer such as Y ₂ O ₃ having an average particle diameter of 0.5 to 3 μm. Then, a green sheet produced by a doctor blade method or the like is wound and formed.

Then, the air electrode / solid electrolyte molded body is
The calcined body is calcined at a temperature of 00 to 1300 ° C. for about 1 to 3 hours, and thereafter, the surface of the calcined solid electrolyte, which is to be a laminated portion of the current collector, is polished smoothly to expose the calcined cathode. A molded body for a current collector is laminated on the surface of the calcined body and the calcined cathode. The molded body for the current collector uses a LaCrO ₃ material,
It is formed by laminating green sheets in the same manner as the solid electrolyte molded body.

The laminate thus manufactured is placed in an oxidizing atmosphere such as air at a temperature of 1300 to 1600 ° C. and 3 to 1 ° C.
Co-sintering is performed by co-firing for about 5 hours to produce a cylindrical cell body.

The fuel electrode is made of a porous cermet material containing 30 to 80% by weight of Ni and the balance of stabilized ZrO ₂ (including a stabilizer such as Y ₂ O ₃ ). Forming a molded body at a predetermined part of the body and sintering it,
Alternatively, after the formation of the air electrode / solid electrolyte / current collector molded body, the fuel electrode molded body may be further laminated and fired at the same time to produce a cylindrical cell body.

Next, for example, a slurry similar to the solid electrolyte molded body is used, and one end of the cell main body is immersed (dipped) in the slurry, so that the outer surface of one end of the cell main body has a gas sealing layer. And dried at 100 to 150 ° C. for 1 to 3 hours. Other methods of applying ceramic slurry include spraying,
There is application by brush or the like. Ceramic slurry is
It is desirable that the sealing member be applied in a slightly larger area than a portion to be externally fitted.

Since the sealing member is required to have gas sealing properties at the time of power generation, for example, ZrO ₂ -based or LaCrO ₃ -based oxide powder having an average crystal grain size of about 0.5 to 3 μm is extruded or hydrostatically molded. (Rubber press) or the like, and cut into a cap shape to produce a ceramic molded body for a sealing member. It is desirable to use yttria partially stabilized zirconia for the gas seal layer and the sealing member.

At this time, the molded body for the sealing member is in contact with the outer peripheral surface of the cell body, and the molded body thickness of the cylindrical portion to be tightened is:
Desirably, it is 0.7 to 1.5 mm. this is,
If the thickness is smaller than 0.7 mm, the sealing member may be damaged during firing. If the thickness is more than 1.5 mm, the cell body and the unsintered gas seal layer may be damaged at the time of sintering shrinkage of the sealing member, and a stack is formed by a plurality of solid oxide fuel cells. The space between the cylindrical solid oxide fuel cells during the process increases,
This is because electrical connection becomes difficult.

When sealing is performed with such a sealing member, the outer diameter increases by the thickness of the cylindrical portion. Therefore, the thickness of the cylindrical portion of the sealing member must be reduced to suppress the increase in the outer diameter. And yttria partially stabilized zirconia which has sufficient strength even if it is thin is desirable.

In order to ensure that the sealing member is arranged at one end of the cell main body with sufficient stability even when the sealing member molded body is inserted into the cell body turned over, the sealing member is sintered. It is preferable that the length of the cylindrical portion with respect to the entire length of the molding for sealing is 40% or more, and the length of the cylindrical portion with respect to the inner diameter of the cylindrical portion of the molding for sealing member is 40% or more.

In order to ensure sufficient contact between the end surface of the cell body and the base of the molding for sealing member, an r-plane formed at the boundary between the inner bottom surface of the base of the molding for sealing member and the inner surface of the cylindrical portion. Is desirably 200 μm or less.

As described above, the radius of curvature of the r-plane at the boundary between the inner bottom surface of the base portion of the molded body for a sealing member and the inner surface of the cylindrical portion is set to 20.
By setting it to 0 μm or less, it is possible to secure contact between the inner bottom surface of the base portion of the sealing member and the end surface of the cell body in the sintering process even if the cell body is turned over. Therefore, when the molded body for a sealing member is externally fitted to the cell body and sintered, the cell body can be placed in a stable posture in which the cell body is overturned, thereby preventing the collapse of the cylindrical solid oxide fuel cell. Can be.

The inner diameter of the cylindrical portion of the molding for the sealing member into which one end of the cell body is inserted is 1.0 mm of the outer diameter of the cell body.
Preferably, it is 5 to 1.25 times. This is because when the inner diameter of the cylindrical portion is smaller than 1.05 times the cell body,
During firing, the sealing member is easily cracked by distortion.
If it is larger than 25 times, a gap may be formed between the sealing member and the cell body, and sealing may not be performed.
In addition, the size and material of the molded body for the sealing member are determined so that the inner diameter of the cylindrical portion when the sealing member is sintered alone is smaller than the outer diameter of the cell body.

Thereafter, as shown in FIG. 2, one end of the cell body 8 is inserted into the cylindrical portion 13a of the molding 11a for the sealing member, and the end face of the cell body 8 is attached to the base of the molding 11a for the sealing member. Abuts against the inner bottom surface of the portion 14a, and in an oxidizing atmosphere such as air,
Firing at a temperature of 1300 to 1600 ° C. for about 1 to 5 hours,
A sealing member is fitted to one end of the cell body via a gas seal layer to obtain a cylindrical solid oxide fuel cell of the present invention.

That is, in order to newly sinter the sealing member after sintering the cell body, the sintering temperature of the gas seal layer and the sealing member is required to be lower than the sintering temperature of the cell body. For example, a fuel cell using LaCrO ₃ -based material
Although it is sintered at about 500 ° C., yttria partially stabilized zirconia can be sintered at a lower temperature of 1400 ° C., so that yttria partially stabilized zirconia is desirable as a sealing member or a gas seal layer.

The inner surface of the cylindrical portion of the sealing member and the gas seal layer are integrated at the time of firing, and the gas seal layer and the outer peripheral surface of one end of the cell body are also integrated at the time of firing. Is joined to the outer peripheral surface of one end of the cell body via the gas seal layer. Further, by integrating the inner bottom surface of the base portion of the sealing member and the end surface of the cell body at the time of firing, the sealing member and the cell body are firmly fixed. The gas sealing layer and the sealing member made of the dense ceramics only need to be able to prevent gas leakage, and particularly preferably have an open porosity of 5% or less.

In the present invention, after the anode slurry is applied to a cell body having an air electrode, a solid electrolyte, and a current collector, the cell body is inserted into the cylindrical portion of the molded member for a sealing member, and The fuel electrode may be baked on the surface of the solid electrolyte by firing the molded body for a sealing member simultaneously with the application film. In this case, a processing step for burning only the fuel electrode can be omitted.

[0051]

EXAMPLES In order to produce a cell body by co-sintering, first, a cylindrical air electrode molded body was produced as follows. La ₂ O ₃ , CaCO ₃ , Mn having a purity of 99.9% or more commercially available
Starting from ₂ O ₃ , it is La _0.8 Ca _0.2 Mn
After weighing and mixing to obtain an O ₃ composition, the mixture was calcined at 1500 ° C. for 3 hours and pulverized to obtain a solid solution powder having an average particle size of 5 μm. Further, a binder was added to the solid solution powder, and a cylindrical air electrode molded body was produced by an extrusion molding method. After drying, the air electrode molded body was debindered and calcined at 1250 ° C. for 10 hours to produce a cylindrical air electrode calcined body.

Next, Y ₂ O ₃ obtained by the coprecipitation method was added to 8
mol% ZrO ₂ having an average particle size of 1 μm
Toluene and a binder were added to the powder to prepare a slurry, and a 130 μm-thick solid electrolyte sheet was prepared by a doctor blade method.

Next, commercially available La _{2 having} a purity of 99.9% or more is used.
Starting from O ₃ , Cr ₂ O ₃ and MgO, this is
a (Mg _0.3 Cr _0.7 ) _0.97 O ₃ The mixture was weighed and mixed so as to obtain a composition, and 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 the solid solution powder to prepare a slurry, and a current collector sheet having a thickness of 130 μm was prepared by a doctor blade method.

The solid electrolyte sheet was wound in a roll around the cylindrical air electrode calcined body, and calcined at 1100 ° C. for 3 hours. After calcination, the surface of the solid electrolyte calcined body which is to be a laminated portion of the current collector sheet is polished flat, and the surface is polished up to the exposed air electrode calcined body. Wrapped around. Thereafter, co-sintering was attempted at 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, and water was added as a solvent to prepare a fuel electrode slurry.
The coating was dried at 0 μm to prepare a cell body having an outer diameter of about 15 mm and a thickness of 2 mm.

Next, water was added as a solvent to ZrO ₂ powder having an average particle diameter of 1 μm containing Y ₂ O ₃ at a ratio of 3 mol% to prepare a slurry for the gas sealing layer. Was immersed, and a ceramic slurry was applied to the outer peripheral surface of one end of the cell body by a dipping method, and dried at 120 ° C. for 1 hour. The thickness was adjusted by changing the viscosity of the slurry. Table 1 shows the average thickness of the gas seal layer after sintering. The end face of the cell body coated with the ceramic slurry is polished and flattened so as to be in close contact with the inner bottom face of the base of the sealing member.

Next, a cap-shaped molded body as a sealing member is manufactured. First, isostatic pressing (rubber pressing) is performed using a ZrO ₂ -based powder having the same composition as the slurry composition for the gas seal layer and containing Y ₂ O ₃ at a ratio of 3 mol% and an average particle size of 1 μm. And cut into a cap shape. Thereafter, one end of the cell body was inserted into the cylindrical portion of the molded body for a sealing member.

After sintering, the overall length of the sealing member in the axial direction is L ₁ , the outer diameter of the base portion is D ₁ , the outer diameter of the cylindrical portion is D ₂ , the length is L ₂ , and the inner diameter is 3D. The size of the sealing member of each sample _{L 2 / L 1 = 0.55,} L 2 / D 3 = 0.50, D
_It was manufactured so that ₁ / D ₂ = 0.80.

The wall thickness t of the cylindrical portion of the molded body for a sealing member, which comes into contact with the outer peripheral surface at one end of the cell body and tightens the cell body, was designed to be 0.7 mm. The thickness after sintering is about 0.5 mm, and the increase in the diameter of the entire cell is about 1 mm.

Thereafter, the fuel electrode layer is formed by sintering at 1400 ° C. for 2 hours in the air, and a cap-shaped sealing member is joined to the outer peripheral surface of one end of the cell body via a gas seal layer. did.

Air is pressurized and injected from the open end on the side where sealing is not performed so that the internal air pressure inside the cell body becomes higher than the external air pressure by +1 kgf / cm ^{2 with} respect to the external air pressure. It was immersed in water, and the presence or absence of bubbles was observed for the presence or absence of a leak at the initial stage.

This sample was allowed to stand at a high temperature of 1000 ° C. in an air atmosphere, cooled to room temperature after 1000 hours, and further heated from room temperature to 1000 ° C. in an air atmosphere, and cooled from 1000 ° C. to room temperature. 10 steps
A cycle load was given by repeating the cycle. The inside of the cell was set to an Air atmosphere, and the outside of the cell was set to an H ₂ atmosphere.
Leakage was observed in the same manner as above for those subjected to reduction treatment by leaving them at 000 ° C. for 1 hour and 100 hours. Table 1 shows the results.

[0063]

[Table 1]

As shown in Table 1, when the thickness of the gas seal layer after sintering is 70 μm to 250 μm, one end of the cell body can be effectively sealed.
It can be seen that the ir cycle load test and the durability under a high-temperature reducing atmosphere are excellent.

However, the sintered gas seal layer has a thickness of 250 μm.
For samples exceeding m, the viscosity of the slurry increases, making it difficult to form the slurry uniformly in the circumferential direction.
When the cross section was planarly polished, the dried slurry became easily broken. Incidentally, in sample No. 9, the dried slurry collapsed when the end face of the cell body was polished. Further, when the gas seal layer exceeds 250 μm, when a large amount of binder is added to the ceramic slurry to increase the viscosity, cracks considered to be caused by non-uniformity of the slurry are generated in the gas seal layer, A gas leak was generated by the reduction treatment (Sample No. 8).

On the other hand, if the gas seal layer is less than 70 μm, gas leakage occurs due to the reduction treatment, and a sufficient gas seal effect cannot be obtained.

Next, the average thickness of the gas leak layer is 100 μm.
Table 2 shows the result of gas leak of a sample which was sealed by applying a ceramic slurry so as to have a thickness of m and changing the shape of the sealing member. The overall length in the axial direction of the sealing member after sintering was L ₁ , the outer diameter of the base portion was D ₁ , the outer diameter of the cylindrical portion was D ₂ , the length was L ₂ , and the inner diameter was D ₃ .

[0068]

[Table 2]

From Table 2, it can be seen that L ₂ / L ₁ is in the range of 0.3 to 0.3.
7, L ₂ / D ₃ is 0.3~0.7, D ₁ / D ₂ ratio is 0.
When satisfying the range of 78 to 0.84, breakage due to stress in sintering shrinkage can be prevented, and it can be seen that it is excellent for the Air high temperature load test, the Air cycle load test, and the reduction treatment.

[0070]

As described in detail above, according to the present invention,
Instead of sealing the one end of the cell body with the mounting member when setting the cell body for power generation in the furnace and performing power generation as in the past, one end of the cell body is sealed with dense ceramics at the cell manufacturing stage. Therefore, one end of the cell body can be easily and reliably sealed, and the sealed state can be checked before the power generation cell body is set in the furnace. Is sufficiently guaranteed. Then, a thickness 70
A ceramic cap-shaped sealing member consisting of a base portion and a cylindrical portion was externally fitted via a gas seal layer made of ceramics having a thickness of up to 250 μm. The size of the main body can be prevented from increasing.

[Brief description of the drawings]

FIG. 1 is a sectional view of a cylindrical solid oxide fuel cell according to the present invention.

FIG. 2 is a cross-sectional view in which a ceramic slurry for a gas seal layer is applied to a cell body and a molded body for a sealing member is inserted.

FIG. 3 is a perspective view showing a cylindrical solid oxide fuel cell.

[Explanation of symbols]

 9 Cell body 8 Gas seal layer 11 Sealing member 13 Cylindrical part 14 Base part

Claims (3)

[Claims] An air electrode is formed on one surface of a cylindrical solid electrolyte, and a fuel electrode is formed on the other surface, and a current collector electrically connected to the air electrode or the fuel electrode and exposed on the outer surface is provided. A thickness of 7 mm is provided on the outer peripheral surface of one end of the cylindrical cell body provided.
A cylindrical solid oxide fuel cell comprising a ceramic cap-shaped sealing member consisting of a base portion and a cylindrical portion externally fitted through a gas seal layer made of ceramic having a thickness of 0 to 250 μm. 2. The cylindrical solid oxide fuel cell according to claim 1, wherein the gas sealing layer and the cap-shaped sealing member are made of ZrO ₂ containing Y ₂ O ₃ . 3. The overall length of the sealing member in the axial direction is L ₁ , the outer diameter of the base portion is D ₁ , the axial length of the cylindrical portion is L ₂ , the outer diameter of the cylindrical portion is D ₂ , and the outer diameter of the cylindrical portion is D ₂ . when an inner diameter set to D _3, together with the D ₁ / D ₂ satisfies the range of 0.78 to 0.84, L ₂ /
L ₁ satisfies the range of 0.3 to 0.7, and L ₂ / D ₃
3 satisfies the range of 0.3 to 0.7.