JP2003036863A - Cell for solid electrolyte type fuel cell and fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cell for a solid electrolyte fuel cell and a fuel cell in which an electric collector is surely connected to the exposed face of an air electrode in the cell for the solid electrolyte fuel cell with a diameter not less than 10 mm and the failure of the exposed surface of the air electrode thereof is prevented. SOLUTION: A solid electrolyte 31 is formed exposed on the surface of a cylindrical air electrode 30 as a part of the air electrode 3. A fuel electrode 33 is formed on the surface of the solid electrolyte 31. An electric collector 35 is formed on the exposed face 37 of the air electrode 30 and the surface of the solid electrolyte 31 near the electrode 30. The solid electrolyte type fuel cell 59 is formed by heating the air electrode 30, solid electrolyte 31 and electric collector 35 at the same time. The solid electrolyte fuel cell 59 has a diameter R that is less than 10 mm, and the cross sectional shape of the exposed face 37 of the air electrode is arcuate.

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 a fuel cell, and more particularly to a cylindrical solid oxide fuel cell having an outer diameter of 10 mm or less and a fuel cell.

[0002]

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

As shown in FIG. 4, a unit cell of a conventional cylindrical fuel cell has a porous air electrode 2 made of a LaMnO ₃ type material having an open porosity of about 30 to 40%, and Y is formed on the surface thereof.
_A solid electrolyte ₃ made of ₂ O ₃ stabilized ZrO ₂ is coated, and a porous Ni-zirconia fuel electrode 4 is further provided on the surface.

In the fuel cell module, each unit cell is connected via a LaCrO ₃ type current collector (interconnector) 5. For power generation, air (oxygen) 6 is flown inside the air electrode 2 and fuel (hydrogen) 7 is flown outside, and 1000 to 1
It is carried out at a temperature of 050 ° C.

As a method of manufacturing the fuel cell as described above, there is a so-called co-sintering method in which at least two of the constituent materials are co-fired in order to simplify the manufacturing process and reduce the manufacturing cost. Proposed. In this co-sintering method, for example, a solid electrolyte molded body and a current collector molded body are wound around a cylindrical air electrode molded body in a roll shape and simultaneously fired, and then a fuel electrode layer is formed on the surface of the solid electrolyte layer. Is the way. In order to simplify the process, a co-sintering method has also been proposed in which a fuel electrode compact is further laminated on the surface of a solid electrolyte compact, and co-firing is performed.

Conventionally, a space between both ends of a solid electrolyte molded body wound around a cylindrical air electrode molded body is polished to form a flat surface having an exposed surface width of about 4 to 5 mm. A solid electrolyte fuel cell having a cylindrical shape with an outer diameter of 15 mm or more is formed by stacking a current collector molded body on and firing it to form a current collector electrically connected to an air electrode having a thickness of 2 mm or more. I was making a cell.

In recent years, there has been an increasing trend toward commercializing the solid oxide fuel cell unit as a vehicle-mounted or portable portable power source. For this reason, the outer diameter of the solid oxide fuel cell unit is set to 10 mm or less. The design has been made to reduce the size and weight.

[0008]

However, when a solid oxide fuel cell having an outer diameter of 10 mm or less is produced, the air electrode is inserted in consideration of the diameter of the air introduction tube inserted into the solid oxide fuel cell. The wall thickness of 0.5-1.
It needs to be 5 mm. Therefore, if an attempt is made to polish such a thin-walled air electrode molded body in the same manner as described above to form a flat surface, it is necessary to widen the exposed surface width of the air electrode in order to ensure bonding with the current collector. Yes, if the width of the exposed surface is widened in this way, the thickness of the air electrode on this exposed surface becomes thinner,
There was a problem that the risk of breakage was extremely high in the subsequent steps.

On the contrary, if it is attempted to secure a predetermined thickness as the thickness of the exposed surface of the air electrode, the width of the exposed surface of the air electrode cannot be widened and the current collector cannot be sufficiently joined. The air inside the solid oxide fuel cell unit leaks from this portion.

According to the present invention, in a solid oxide fuel cell having an outer diameter of 10 mm or less, a current collector can be reliably joined to the exposed surface of the air electrode, and damage to the exposed surface of the air electrode can be prevented. It is an object to provide a battery cell and a fuel cell.

[0011]

In the solid oxide fuel cell of the present invention, a solid electrolyte is formed on the surface of a cylindrical air electrode so that a part of the air electrode is exposed. Along with forming a fuel electrode on the surface, the exposed surface of the air electrode and the solid electrolyte surface in the vicinity thereof, a current collector is formed, and at least the air electrode, the solid electrolyte and the current collector are co-fired. The solid electrolyte fuel cell having the outer diameter R of 10 mm or less and the exposed surface of the air electrode having an arc-shaped cross section.

In the present invention, since the cross-sectional shape of the exposed surface of the air electrode exposed from the solid electrolyte is arcuate, that is, arcuate plate-like, the outer diameter R of the solid oxide fuel cell is 10
Even if the thickness of the air electrode is less than or equal to mm, the junction area of the current collector can be expanded without thinning the thickness of the exposed surface, preventing damage to the exposed surface of the air electrode. In addition, the current collector can be securely joined to the exposed surface of the air electrode, and the actual length of the exposed surface width is longer than the actual length of the exposed width obtained by flattening. The current collection performance can be improved.

That is, a solid oxide fuel cell using an air electrode having a small thickness and a large diameter is difficult to manufacture because it is difficult to maintain its shape. The oxygen-containing gas (air) supply rate can be improved, and the power generation performance can be improved. On the other hand, since it is necessary to reliably prevent the oxygen-containing gas from leaking in the portion where the current collector is formed, the exposed electrode of the air electrode has an arc-shaped cross section.

Further, in the present invention, it is desirable that the width B in the circumferential direction of the exposed surface of the air electrode satisfies 0.2R to 0.6R. By setting the width B in the circumferential direction of the exposed surface of the air electrode in an appropriate range, the polishing process of the exposed surface of the air electrode and the solid electrolyte surface in the vicinity thereof can be easily performed, and at the same time from the end of the current collector. It is possible to prevent the gas leak and the internal crack of the current collector, and moreover, it is possible to surely join the current collector and improve the current collecting performance.

Further, in the present invention, it is desirable that the thickness t of the air electrode is 0.5 to 1.5 mm. With such a thickness t, a space into which the air introduction tube can be inserted can be formed, and even if it is thin as described above, the exposed surface of the exposed air electrode does not need to be polished so much. Can be prevented from being damaged.

The fuel cell of the present invention comprises a reaction vessel containing a plurality of the solid oxide fuel cell cells. In the present invention, even when a solid oxide fuel cell having an outer diameter R of 10 mm or less is produced, the current collector can be reliably joined to the exposed surface of the air electrode and damage to the exposed surface of the air electrode can be prevented. A small fuel cell can be manufactured and long-term use becomes possible.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a cross section of a solid oxide fuel cell according to the present invention. The solid oxide fuel cell has an outer diameter R of 10 mm or less in a cylindrical shape.
In the solid oxide fuel cell, a solid electrolyte 31 is formed on the upper surface of a cylindrical porous air electrode 30, and a porous fuel electrode 33 is formed on the upper surface of this solid electrolyte 31 to form a cell body 34. A current collector (interconnector) 35 is electrically connected to the air electrode 30. still,
The outer diameter R of the solid oxide fuel cell means the maximum outer diameter of the solid oxide fuel cell, and in this example,
It is the diameter in the direction orthogonal to the portion of the fuel electrode 33 formed facing the current collector 35. The outer diameter R is preferably 5 mm or less from the viewpoint of miniaturization.

That is, both ends of the solid electrolyte 31 are open, and the air electrode 3 formed on the inner surface of the solid electrolyte 31.
The exposed surface 37 and the solid electrolyte 31 are partially exposed.
The surfaces of both ends of the current collector 35 are covered with the current collector 35.
Are bonded to both end surfaces of the solid electrolyte 31 and the exposed surface 37 of the air electrode 30. The current collector 35 needs to be securely joined so that the air inside the cell body 34 does not leak from the exposed surface 37 of the air electrode 30 between both ends of the solid electrolyte 31. Current collector 3 electrically connected to the air electrode 30
5 is formed on the outer surface of the cell body 34 and is not electrically connected to the fuel electrode 33. The exposed surface 37 of the air electrode 30 is
It is formed in the longitudinal direction of the cell body 34.

The exposed surface 37 of the air electrode 30 to which the current collector 35 is joined and both end surfaces of the solid electrolyte 31 are formed in an arc-shaped cross section, and the exposed surface 37 and both end portions of the solid electrolyte 31 are included. The radius of curvature of the open portion is the same as or slightly larger than the radius (outer diameter R / 2) of the solid oxide fuel cell unit. That is, the exposed surface 3 of the air electrode 30
The radius of curvature of 7 is larger than the radius of the air electrode 30 other than the exposed surface 37, and the radius of the solid oxide fuel cell (outer diameter R
/ 2), or slightly larger than that.

The width B in the circumferential direction of the exposed surface 37 of the air electrode 30 satisfies 0.2R to 0.6R, where R is the outer diameter of the solid oxide fuel cell, as shown in FIG. There is. By setting the width B in such a range, the air electrode 3
No. 0 exposed surface 37 and the surface of both ends of the solid electrolyte in the vicinity thereof can be easily performed, and the current collector 35 is exposed to the exposed surface 37 of the air electrode 30 and surfaces of both ends of the solid electrolyte 31 in the vicinity thereof. Since it is possible to reliably bond the electrode to the exposed surface 37 of the air electrode 30 and to prevent gas leakage from the end of the current collector 35 and internal cracks in the current collector 35, Sufficient current collection performance can be improved.

On the other hand, when the width B becomes smaller than 0.2R, the solid electrolyte 31 for forming the arc-shaped slope is formed.
It is difficult to remove the steps at the both ends of the solid electrolyte, and some of the steps remain, or both ends of the solid electrolyte 31 are easily chipped. Even if a cell is produced, a gas leak occurs from the end of the current collector. Easier to do. On the other hand, when the width B becomes larger than 0.6R, although arcuate slope can be easily formed, moth
The current collector for preventing the leak is the end of the solid electrolyte 31.
Same as above, because the thickness of the part that is laminated to the part becomes thin.
It is easy for some parts to generate gas leak defects. The width B of the exposed surface 37 of the air electrode 30 in the circumferential direction is particularly preferably 0.3R to 0.5R.

The thickness t of the air electrode 30 is 0.5 to 1.5 m.
It is desirable that it is m. With such a thickness t, even if the outer diameter R is 10 mm or less, particularly 5 mm or less, a space into which the air introduction tube can be inserted can be formed, and even if it is thin, exposed air Pole 30
Since the exposed surface 37 of the air electrode 30 does not need to be polished so much, damage to the air electrode 30 can be prevented. On the other hand, the thickness t of the air electrode 30
When it is less than 0.5 mm, it is difficult to fabricate cells, and when it is more than 1.5 mm, it tends to be difficult to insert the air introduction pipe when the outer diameter R is 5 mm or less. The thickness t of the air electrode 30 is preferably 0.5 to 1 mm from the viewpoint that it can sufficiently cope with an outer diameter R of 5 mm or less.

The solid electrolyte 31 contains, for example, 3 to 15 mol%.
Partially stabilized or stabilized ZrO ₂ containing Y ₂ O ₃ is used. Further, as the air electrode 30, for example, La
LaMnO _{3 in} which 10 to 30 atomic% of Ca or Sr is substituted with 5 to 20 atomic% of Y is used, and as the current collector 35, for example, L in which Cr is substituted with 10 to 30 atomic% of L is used.
aCrO ₃ is used.

As the fuel electrode 33, 50 to 80% by weight N
A ZrO ₂ (Y ₂ O ₃ containing) cermet containing i is used. The solid electrolyte 31, the current collector 35, and the fuel electrode 33 are not limited to the above examples, and known materials may be used. The air electrode 30 may be made of a perovskite type composite oxide containing at least La and Mn.

In the method of manufacturing the solid oxide fuel cell having the above structure, first, a cylindrical air electrode molded body is formed. This cylindrical air electrode formed body has, for example, La ₂ O ₃ , Y ₂ O ₃ , CaCO ₃ and Mn ₂ O according to a predetermined composition.
Weigh and mix the ₃ raw materials.

Thereafter, for example, calcination is performed at a temperature of about 1500 ° C. for 2 to 10 hours, and then pulverized to a particle size of 4 to 8 μm. The prepared powder is mixed with a binder and kneaded to prepare a cylindrical air electrode formed body by an extrusion molding method, and further subjected to binder removal treatment and calcination at 1200 to 1250 ° C. to form a cylindrical air electrode temporary body. Create a fired body.

Next, ZrO ₂ powder containing at least one of Y ₂ O ₃ and CaO and CeO ₂ powder containing a predetermined amount of Y ₂ O ₃ or Sm ₂ O ₃ are mixed and calcined, and then the particle size is adjusted. Toluene is added to the above mixed powder as a solvent to prepare a paste having a function as a Mn diffusion preventing layer. This paste was applied to the surface of a cylindrical air electrode calcined body to form a coating film of the Mn diffusion preventing layer.

Next, a sheet-shaped first solid electrolyte molded body is prepared by adding toluene, a binder, and a commercially available dispersant to a predetermined powder to make a slurry, and by a method such as a doctor blade, for example, a thickness of 100 to 120 μm. The first solid electrolyte molded body is separated from the surface of the coating film of the Mn diffusion preventive layer formed on the surface of the cylindrical air electrode calcined body at predetermined intervals at both ends. It is wound and calcined as described above to form a first solid electrolyte calcined body on the surface of the air electrode calcined body. Although the first solid electrolyte molded body was calcined, it may not be calcined.

Next, a polishing surface having an arc-shaped groove having a predetermined curvature is provided so that the cross section between both ends of the first solid electrolyte calcined body and the exposed surface of the air electrode calcined body has an arc shape. A polishing jig is used to simultaneously polish both end portions of the first solid electrolyte calcined body and the exposed surface of the air electrode calcined body.

Next, a sheet-shaped first fuel electrode compact is prepared. First, for example, Ni / YSZ prepared in a predetermined ratio
Toluene and a binder are added to the mixed powder to prepare a slurry. Similar to the preparation of the first solid electrolyte molded body, it is molded and dried to form, for example, a sheet-shaped second solid electrolyte molded body having a thickness of 15 μm.

After the slurry for the first fuel electrode layer molded body was printed on the second solid electrolyte molded body and dried, the first fuel electrode layer molded body was formed on the first solid electrolyte calcined body. Second
The solid electrolyte compact is wound and laminated so that the second solid electrolyte compact is in contact with the portion other than the polished surface of the first solid electrolyte calcined body.

Next, 1 is attached to the exposed surface of the arc-shaped calcinated air electrode body and both end portions of the first solid electrolyte calcined body near the exposed surface.
A current collector molded body having a thickness of 00 to 120 μm is attached and laminated.

The cylindrical laminated compact thus manufactured is housed in a groove on a zirconia base plate having a groove having a triangular cross section so that the collector compact faces downward. . Next, in order to press both ends of the laminated molded body to the base plate side, zirconia-based blocks are placed on the upper surfaces of both end portions of the laminated molded body, and on the upper surfaces of these zirconia-based blocks, zirconia-based Cylindrical ceramic is divided into ⅓ and circular arc plate-shaped ceramics are laid over and placed, and fired.

The firing is carried out in an oxidizing atmosphere such as air at 130.
Co-sintering is performed by simultaneously firing at a temperature of 0 to 1600 ° C. for about 1 to 10 hours.

Next, a second fuel electrode compact is formed. ZrO containing Ni powder and Y ₂ O ₃ prepared in a predetermined ratio
₂ (YSZ) powder, Zr and Y metal organic salt to which toluene and a binder were added to prepare a slurry, which was prepared by co-sintering. The slurry is applied so as to have a thickness of 100 μm and dried. After that, in an oxidizing atmosphere such as the air, 1000-
Heat treatment (baking) is performed at a temperature of 1300 ° C., and a cell having the second fuel electrode formed is formed.

In the above example, an example in which the air electrode calcined body and the first solid electrolyte calcined body were formed was explained, but these may be the air electrode molded body and the first solid electrolyte molded body. .

In the fuel cell of the present invention, for example, as shown in FIG. 3, an oxygen-containing gas chamber partition plate 5 is provided in a reaction vessel 51.
3, the combustion chamber partition plate 55 and the fuel gas chamber partition plate 57 are used to form the oxygen-containing gas chamber A, the combustion chamber B, the reaction chamber C, and the fuel gas chamber D.
Are formed. The plurality of bottomed cylindrical solid oxide fuel cell units 59 are housed in the reaction vessel 51, and these solid oxide fuel cell units 59 are formed on the combustion chamber partition plate 55. The opening 61 is inserted and fixed in the insertion hole 60, and the opening 61 projects from the combustion chamber partition plate 55 into the combustion chamber B, and the oxygen-containing gas introduction pipe fixed to the oxygen-containing gas chamber partition plate 53 is provided therein. One end of (air introducing pipe) 63 is inserted. In the combustion chamber partition plate 55, a plurality of exhaust holes 64 are formed in order to discharge the excess unreacted fuel gas from the reaction chamber C to the combustion chamber B. A supply hole for supplying the reaction gas from the chamber D into the reaction chamber C is formed.

Further, in the reaction vessel 51, a fuel gas inlet port 65 for introducing a fuel gas composed of hydrogen, for example,
An oxygen-containing gas introduction port 67 for introducing air and an exhaust port 69 for discharging the gas burned in the combustion chamber B are formed.

In such a solid oxide fuel cell, the oxygen containing gas from the oxygen containing gas chamber A, eg, air, is supplied into the solid oxide fuel cell 59 via the oxygen containing gas introducing pipe 63, respectively. In addition, the fuel gas from the fuel gas chamber D is supplied between the plurality of solid oxide fuel cell units 59 to react in the reaction chamber C to generate electricity, and excess air and unreacted fuel gas are burned in the combustion chamber B. Then, the burned gas is discharged to the outside through the exhaust port 69.

The fuel cell of the present invention is not limited to the fuel cell shown in FIG. 3 described above, and it is sufficient that a plurality of the above-mentioned fuel cells are accommodated in the reaction vessel.

[0041]

Example In order to manufacture a cylindrical solid oxide fuel cell unit by the co-sintering method, first, a cylindrical air electrode calcined body was manufactured by the following procedure. La with a purity of 99.9% or more on the market
₂ O ₃ , Y ₂ O ₃ , CaCO ₃ , and Mn ₂ O ₃ were used as starting materials, and calcined at 1500 ° C. for 3 hours to _obtain (La _0.56 Y _0.14 Ca
_0.3 ) _0.97 MnO ₃ was prepared, and then pulverized to a particle size of 4 μm.

A binder was added to the solid solution powder of which particle size was adjusted, and cylindrical air electrode molded bodies having different outer diameters were produced by an extrusion molding method. The air electrode formed body was dried and then debindered and calcined at 1250 ° C. for 10 hours to prepare a cylindrical air electrode calcined body.

Next, ZrO ₂ containing Y ₂ O ₃ obtained by the coprecipitation method in an amount of 8 mol% and having an average particle size of 1 to ₂ μm is used.
A slurry was prepared using the powder, and sheets having a thickness of 100 μm and a thickness of 15 μm as first and second solid electrolyte molded bodies were prepared by a doctor blade method.

Next, the production of the first and second fuel electrode compacts will be described. For the first fuel electrode compact, a ZrO ₂ powder containing Y ₂ O ₃ having an average particle size of 0.6 μm in an amount of 8 mol% with respect to Ni powder having an average particle size of 0.4 μm was prepared. / YSZ ratio (weight fraction) was adjusted to 65/35, pulverized and mixed, and slurried.
Then, the prepared slurry was printed on the entire surface of the second solid electrolyte molded body so as to have a thickness of 30 μm, and dried.

On the other hand, the second fuel electrode compact has an average particle size of 1
Y ₂ having an average particle size of 1 to ₂ μm with respect to Ni powder of 0 μm
ZrO ₂ powder containing O ₃ in a proportion of 8 mol%, and Z
Prepare each metal organic salt of r and Y, Ni / YSZ
The mixture was prepared and mixed so that the ratio (weight fraction) was 72/28, and then a slurry was prepared by using a commercially available organic solvent and a binder to adjust the viscosity.

Next, commercially available La _{2 having} a purity of 99.9% or more is used.
O ₃ , Cr ₂ O ₃ , and MgO are used as starting materials, and La
(Mg _0.3 Cr _0.7 ) _0.97 O ₃ Weighed and mixed to obtain a composition, calcinated and pulverized at 1500 ° C. for 3 hours, and a slurry is prepared using this solid solution powder. A molded body was produced.

The paste used as the Mn diffusion preventing layer is Y ₂
ZrO ₂ powder (8YSZ) containing 8 mol% of O ₃ ,
YD represented by the composition formula (CeO ₂ ) _0.7 (Y ₂ O ₃ ) _0.3
C powder was mixed so that 8YSZ: YDC = 1: 9 (weight fraction), and toluene was added to this mixed powder as a solvent to prepare.

First, four kinds of cylindrical air electrode calcined bodies having different outer diameters were prepared. The paste of the Mn diffusion preventive layer was applied to the surface of the air electrode calcined body, and the first solid electrolyte compact was applied to this coating film at both ends.
Wrap it in a roll with an opening of 5 mm width 1150 ° C
It was calcined under the condition of 5 hours.

After the calcination, a radius of curvature of R / 2 is formed between the both ends of the first solid electrolyte calcined body so as to expose the air electrode calcined body with each exposed width B shown in Table 1. From the groove
It is sliding the polishing jig in the longitudinal direction having a polishing surface that, or by using a flat polishing jig, between the two ends of the first solid electrolyte calcined body and the exposed surface of the air electrode calcined body at the same time Polished and processed.

Next, the second solid electrolyte compact having the fuel electrode compact formed on the surface of the first solid electrolyte calcined compact is brought into contact with the first solid electrolyte calcined compact and the second solid electrolyte compact. After being laminated and dried, a current collector molded body was attached to the above-mentioned polished portion.

Then, the cylindrical laminated compact was placed sideways in the groove of the zirconia base plate, and a zirconia block (a length of 20 mm obtained by dividing a zirconia tube in half) was formed on the upper surfaces of both ends of the laminated compact. The ceramics obtained by dividing a zirconia tube in half were laid over each block, and co-sintering was attempted under the conditions of 1500 ° C. for 6 hours in the atmosphere.

On the surface of the first fuel electrode of the produced co-sintered body,
Apply and dry the prepared slurry of the second fuel electrode,
Then heat treatment (baking) at 1300 ° C for 1 hour
By carrying out, a cylindrical solid electrolyte type cell was produced.

Then, in the obtained solid oxide fuel cell, the outer diameter R of the cell was measured, the width B of the exposed surface of the air electrode and the thickness t of the air electrode were measured, and both ends of the current collector were measured. A gas leak test was conducted, the presence or absence of breakage inside the cell cross section, and the initial power density measurement by power generation were evaluated. The results are also shown in Table 1.

For power generation, air was flown inside the cell and hydrogen was flown outside at 1000 ° C. using each of the above cells, and the initial value when the output value became stable was measured and evaluated.

[0055]

[Table 1]

From Table 1, sample No. 1 in which the exposed surface of the air electrode was flat-machined In No. 9, the exposed width B was as wide as 1.5 mm, but the cell outer diameter R was 10 mm or less, particularly 5 mm or less, so that the exposed surface of the air electrode was thin and cracks were generated in this portion. . This increased the actual resistance of the air electrode and lowered the initial power density.

On the other hand, in the sample of the present invention in which the exposed surface of the air electrode is curved in an arc shape, even if the cell outer diameter R is 10 mm or less, particularly 5 mm or less, the exposed width B of the exposed surface of the air electrode is not less than a certain value. It can be seen that there is no gas leakage from both ends of the current collector, no destruction inside the cell cross section, and the initial output density due to power generation is as high as 0.41 W / cm ² or more.

[0058]

As described above in detail, in the solid oxide fuel cell of the present invention, the exposed surface of the air electrode exposed from the solid electrolyte has an arc-shaped cross section, in other words, an arc plate shape. The outer diameter R of the electrolyte fuel cell is 10 m
Even if the thickness is less than m, even if the thickness of the air electrode is thin, the junction area of the current collector can be expanded without reducing the thickness of the exposed surface so much, preventing damage to the exposed surface of the air electrode. In addition, the current collector can be securely joined to the exposed surface of the air electrode, and the actual length of the exposed surface width is longer than the actual length of the exposed width obtained by flattening. The current collection performance can be improved. As a result, a gas leak problem,
In addition, it is possible to prevent adverse effects on cell performance due to cell damage,
It becomes possible to maintain and maintain a stable and high power density.

[Brief description of drawings]

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

FIG. 2 is a transverse sectional view for explaining an exposed surface of an air electrode.

FIG. 3 is an explanatory view showing a fuel cell of the present invention.

FIG. 4 is a perspective view showing a conventional cylindrical solid oxide fuel cell unit.

[Explanation of symbols]

30 ... Air electrode 31 ... Solid electrolyte 33 ... Fuel pole 35 ... Current collector 37 ... exposed surface R ... Outer diameter of solid oxide fuel cell B: circumferential width of exposed surface of air electrode t ... Air electrode thickness

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Claims (4)

[Claims] 1. A solid electrolyte is formed on a surface of a cylindrical air electrode so that a part of the air electrode is exposed, a fuel electrode is formed on the surface of the solid electrolyte, and an exposed surface of the air electrode is formed. And a solid electrolyte fuel cell having a current collector formed on the surface of the solid electrolyte in the vicinity thereof and at least the air electrode, the solid electrolyte and the current collector being co-fired. Is 10 mm or less, and the cross-sectional shape of the exposed surface of the air electrode is an arc shape. 2. The width B in the circumferential direction of the exposed surface of the air electrode is
The solid oxide fuel cell according to claim 1, which satisfies 0.2R to 0.6R. 3. The solid oxide fuel cell according to claim 1, wherein the thickness t of the air electrode is 0.5 to 1.5 mm. 4. A fuel cell, characterized in that a plurality of solid oxide fuel cell units according to any one of claims 1 to 3 are housed in a reaction vessel.