JPH06223847A - Cell for solid electrolyte type fuel cell battery and its manufacture - Google Patents

Abstract

PURPOSE:To provide a cell for a solid electrolyte type fuel cell battery which is easy to handle and easy to seal between a fuel passage and an air passage even in case of the thin film formation of electrolyte plates so as to lower the inside resistance of the electrolyte plates, and its manufacture. CONSTITUTION:A cell for a solid electrolyte fuel cell battery is such that solid electrolyte plates 12 made of stabilized zirconia and formed in a fine structure are integrated via a reinforcing ceramic 14. The reinforcing ceramic 14 is a slanted ceramic that ceramic layers 14a-14i with different thermal properties are laminated so that it may be formed in a slanted structure by changing thermal properties such as thermal expansion in sequence. The thermal properties of the ceramic layers 14a-14i having in contact with the solid electrolyte plates 12 are approximated to those of the solid electrolyte plates and at least one of the ceramic layers 14a-14i is a porous layer through which air or fuel fluid used for time fuel cell battery is permeable.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cell for a solid oxide fuel cell and a method for producing the same, and more specifically, a plurality of solid electrolyte plates each made of an ion conductive ceramic and formed in a dense structure are reinforced. The present invention relates to a cell for a solid oxide fuel cell integrated via a ceramic body and a method for manufacturing the same.

[0002]

2. Description of the Related Art Solid electrolyte fuel cells are expected to have higher power generation efficiency as compared with power generation efficiency of thermal power generation, and therefore, many studies are currently being conducted. As a solid electrolyte plate used in such a solid oxide fuel cell, a solid electrolyte plate made of a stabilized zirconia fired body to which a stabilizer such as yttria is added and fired is used.
A solid oxide fuel cell using such a solid electrolyte plate has a flat plate type in which flat plates are stacked as shown in FIG. 4 in order to reduce the internal resistance of the inside of the cell and increase the electrode area per unit capacity. It is suitable. The solid oxide fuel cell shown in FIG. 4 has a solid electrolyte plate 1 made of a stabilized zirconia sintered body.
04, air electrode 10 arranged with the solid electrolyte plate 104 sandwiched therebetween
2 and the fuel electrode 106 form a single cell 110. Further, between the single cells 110, a bipolar plate 108 in which a plurality of concave grooves serving as fuel or air passages are engraved is arranged. The fuel channel and the air channel are the single cell 11
The grooves are engraved so that they flow in directions orthogonal to each other with 0 interposed therebetween.

[0003]

According to the flat plate type solid oxide fuel cell shown in FIG. 4, the output density per unit capacity is high and the size can be increased. However, FIG.
Practical application of the flat-plate type solid oxide fuel cell shown in FIG. The reason is that in the flat-plate type solid oxide fuel cell shown in FIG. 4, the solid electrolyte plate 104 is thinned in order to reduce the internal resistance of the solid electrolyte plate 104 made of the stabilized zirconia sintered body, and Since it is necessary to operate the fuel cell at a high temperature of about 1000 ° C., it is extremely difficult to sufficiently seal the fuel passage and the air passage through the solid electrolyte plate 104. Moreover,
If the solid electrolyte plate 104 is made thin, the mechanical strength of the single cell 110 is reduced, and it becomes difficult to handle the single cell 110 and it becomes more difficult to seal the fuel flow path and the air flow path. Therefore, an object of the present invention is to reduce the internal resistance of the solid electrolyte plate, and even if the solid electrolyte plate is thinned, the solid electrolyte fuel is easy to handle and the fuel flow path and the air flow path are easily sealed. It is to provide a battery cell and a manufacturing method thereof.

[0004]

DISCLOSURE OF THE INVENTION As a result of studies to achieve the above object, the inventors of the present invention have found that a plurality of ceramic layers having different thermal characteristics are laminated, and at least one of the ceramic layers is made of a fuel. A slanted ceramic body, which is a porous layer through which a fluid such as air or fuel used in a battery can pass, is used as a solid electrolyte by integrating cells on both sides of a solid electrolyte plate as a reinforcing material. The present inventors have found that the electrolyte plate can be reinforced and the fuel flow path and the air flow path can be easily sealed, and have reached the present invention.
That is, the present invention is a cell for a solid oxide fuel cell in which each of a plurality of solid electrolyte plates made of an ion conductive ceramic and formed in a dense structure is integrated via a reinforcing ceramic body, The reinforced ceramic body is a ceramic body in which a plurality of ceramic layers having different thermal characteristics are laminated so that thermal characteristics such as a thermal expansion coefficient are sequentially changed to form an inclined structure. A solid electrolyte type in which the thermal characteristics of the ceramic layers in contact are similar to those of a solid electrolyte plate, and at least one of the ceramic layers is a porous layer through which a fluid such as air or fuel used in a fuel cell can pass. It is in a fuel cell.

Further, according to the present invention, each of a plurality of solid electrolyte plate forming green sheets forming a solid electrolyte plate made of an ion conductive ceramic is replaced with a plurality of reinforcing ceramic green sheets forming a reinforcing ceramic body. When a cell for a solid oxide fuel cell is manufactured by stacking and firing through the ceramics, a ceramic which is located substantially in the center of the reinforcing ceramic body and which contacts the solid electrolyte plate from the central layer which is the most porous ceramic layer. The ceramic component of the solid electrolyte plate forming green sheet and the ceramic component of the central layer forming green sheet forming the central layer are mixed so as to form a graded structure in which the composition between layers gradually changes. And forming a plurality of inclined green sheets having different compositions from each other, and then forming the electrolyte plate green sheet. A plurality of inclined green sheets are sequentially laminated to form a laminated body so that the inclined structure is formed between the central layer forming green sheet and the central layer forming green sheet, and then the laminated body is formed to form a solid electrolyte plate. There is provided a method for producing a cell for a solid oxide fuel cell, which comprises firing at a densification temperature of a green sheet or higher and a densification temperature of a green sheet for forming a central layer or lower.

In the present invention, the reinforcing ceramic body has an inclined structure in which the degree of porosity of each ceramic layer sequentially changes, and the central layer located substantially in the center of the reinforcing ceramic body has the most porous structure. The ceramic layer in contact with the solid electrolyte plate has a dense structure similar to that of the solid electrolyte plate, and the ceramic layer in contact with the ceramic layer of the central layer has a porous structure similar to that of the central layer, and fuel or air is contained in the ceramic layer. Can be easily transmitted. In addition, the reinforcing ceramic body is composed of a plurality of ceramic layers formed by mixing the ceramic component forming the solid electrolyte plate and the ceramic component forming the central layer having the most porous structure, and is in contact with the solid electrolyte plate. The composition of the ceramic layer is close to the composition of the solid electrolyte plate, the composition of the ceramic layer in contact with the central layer is similar to the composition of the ceramic layer of the central layer, or the solid electrolyte plate is obtained by adding a stabilizer such as yttria. It is possible to easily manufacture a cell for a solid oxide fuel cell by using the stabilized zirconia fired body thus obtained, and the central layer having the most porous structure being the alumina fired body.

[0007]

According to the present invention, since the solid electrolyte plate is reinforced by the reinforcing ceramic body, even if the solid electrolyte plate is made thin, the mechanical strength of the cell itself is not lowered. Furthermore, since this reinforcing ceramic body is a ceramic body in which thermal characteristics such as the coefficient of thermal expansion sequentially change to form an inclined structure, the solid electrolyte plate and the reinforcing ceramic body do not separate due to heat. Further, the fuel or air can permeate through the porous ceramic layer provided between the solid electrolyte plates. Therefore, the fuel or air can be supplied by supplying it to the exposed side end surface of the reinforcing ceramic body exposed to the side end surface of the cell, and as in the conventional flat plate type solid oxide fuel cell shown in FIG. In addition, it is not necessary to form the concave groove over the entire surface of the solid electrolyte plate, and it is possible to easily perform sufficient sealing between the cell and the fuel flow path and the air flow path.

[0008]

EXAMPLES The present invention will be described in more detail by way of examples. FIG. 1 is a perspective view of a cell for a solid oxide fuel cell (hereinafter, may be referred to as a cell) 10 according to an embodiment of the present invention. The cell 10 comprises a rectangular solid electrolyte plate 12 made of a stabilized zirconia fired body to which yttria (Y ₂ O ₃ ) is added as a stabilizer, and a reinforcing ceramic body 14, on each of the front and back surfaces. 14, 14 are integrally provided. The reinforcing ceramic body 14 is formed by a plurality of ceramic layers 14a to 14i as shown in FIG. The ceramic layers 14a to 14i are formed by mixing an alumina component and a stabilized zirconia component, and are ceramic layers that sequentially differ in thermal characteristics and porous degree. In this embodiment, the ceramic layer 14a
And ceramic layer 14i, ceramic layer 14b and ceramic layer 14h, ceramic layer 14c and ceramic layer 14
g, and the ceramic layer 14d and the ceramic layer 14f have substantially the same thermal characteristics and porous degree.

Therefore, the degree of porosity of the ceramic layers forming the reinforcing ceramic body 14 is in the following order. 12 <14a <14b <14c <14d <14e>14f>14g>14h>14i> 12 Incidentally, 12 is a solid electrolyte plate, and 14a to 14i are ceramic layers. Here, the ceramic layers 14a and 14i contacting the solid electrolyte plates 12 and 12 are the ceramic layers 1
Among 4a to 14i, the ceramic layer has the lowest amount of alumina component (the highest amount of stabilized zirconia component),
The thermal characteristics and the denseness (the degree of porosity) are similar to those of the solid electrolyte plates 12, 12. Further, in the reinforcing ceramic body 14 of the present embodiment, a plurality of layers including the ceramic layer 14e having the highest degree of porosity can allow fuel or air to permeate.

Further, the ceramic layer 14e located substantially in the central portion of the reinforcing ceramic body 14 includes ceramic layers 14a to 14a.
14i is the ceramic layer having the largest amount of alumina component (the smallest amount of stabilized zirconia component). In the present embodiment, the ceramic layers 14d and 14f that are in contact with the ceramic layer 14e contain a slightly larger amount of the stabilized zirconia component than the ceramic layer 14e, but the composition is similar to that of the ceramic layer 14e and the thermal characteristics Also, the degree of porousness (denseness) is similar to that of the ceramic layer 14e.

In the rectangular cell 10 shown in FIG. 1 in which the reinforcing ceramic body 14 and the solid electrolyte plates 12 and 12 having such a structure are integrated, the side surfaces of the reinforcing ceramic body 14 are parallel to each other. Airtight layers 16, 16 made of a platinum thin film having excellent airtightness are formed on a pair of side end faces. The airtight layers 16 and 16 may be thin films of perovskite type oxide such as barium titanate (BaTiO ₃ ). By forming the airtight layers 16 and 16, the air flow A or the fuel flow B can be transmitted from one of the exposed end surfaces where the main body of the reinforcing ceramic body 14 is exposed to the other exposed end surface. Reinforcing ceramic bodies 14 and 14 having airtight layers 16 and 16 formed on the side end faces thereof so that the air flow A and the fuel flow B are permeated in directions orthogonal to each other with the solid electrolyte plate 12 interposed therebetween. And stack.

By inserting the rectangular cell 10 shown in FIG. 1 into the fuel cell substrate 24, as shown in FIG. 3, a solid oxide fuel cell can be formed. In FIG. 3, on the inner wall surfaces of the fuel cell substrates 24, 24,
The air supply groove 20 and the fuel supply groove 22 are formed in a direction orthogonal to each other, and each of the air supply grooves 20 faces the exposed end surface into which the air flow A shown in FIG. 1 is blown, and each of the fuel supply grooves 22. Faces the exposed end surface into which the fuel flow B shown in FIG. 1 is blown. Thus, in this embodiment, the cell 10, the air supply groove 20 and the fuel supply groove 22 are the same as the cell 10
Is in contact with the side end surface of. Therefore, as compared to the case where the air supply groove or the fuel supply groove is in contact with the thin single cell 110 over substantially the entire surface like the conventional cell 100 shown in FIG. Also, the seal with the fuel supply groove 22 is easy. The cross section on the right side and the cross section on the left side of the alternate long and short dash line in FIG.

In the cell 10 of this embodiment, each of a plurality of green sheets for forming a solid electrolyte plate forming a solid electrolyte plate 12 made of zirconia added with yttria as a stabilizer is provided with a reinforcing ceramic body 14. It can be manufactured by laminating and firing a plurality of reinforcing ceramic green sheets to be formed. In this embodiment, the green sheet for forming the electrolyte plate has a thickness of 0.05
The reinforcing ceramic body green sheet has a rectangular shape with a thickness of 0.2 mm or less and a side of 500 mm or less. In this reinforced ceramic body green sheet, the gradient in which the composition between the alumina ceramic layer 14e having the most porous structure and located at substantially the center of the reinforced ceramic body 14 to the ceramic layers 14a and 14i in contact with the solid electrolyte plate 12 is gradually changed. A plurality of sheets having different compositions by mixing the zirconia (containing yttria) component of the electrolyte sheet forming green sheet and the alumina component of the central layer forming green sheet forming the ceramic layer 14e so as to form a structure. Forming a green sheet for tilting. In this example, since platinum (Pt) for the catalyst was blended in the alumina forming the green sheet for forming the central layer, platinum in the blending ratio of the alumina component was also used in the other tilting green sheets.
It also contains (Pt). Incidentally, as a catalyst to be mixed in the green sheet for forming the central layer, in addition to platinum (Pt), silver (Ag)
Can also be used.

Then, a plurality of tilting green sheets are sequentially laminated so as to form the tilted structure between the electrolyte plate forming green sheet and the central layer forming green sheet to form a laminate. To do. The obtained laminate is
It is a dice having a thickness of 5 to 50 cm and a side of 50 cm. Then, the laminate is fired at a temperature equal to or higher than the densification temperature of the electrolyte sheet forming green sheet and equal to or lower than the densification temperature of the central layer forming green sheet. In this example, the electrolyte sheet forming green sheet was composed of only the zirconia component, and the central layer forming green sheet was composed of only the alumina component. Therefore, the firing temperature was set to 1300 to 1600 ° C. The side end faces of the reinforcing ceramic body 14 constituting the obtained die-shaped fired body are formed, and platinum (Pt) paste is applied to the pair of side end faces parallel to each other to form the airtight layers 16, 16. The airtight layers 16, 16 are the airtight layers 16, 1 of the reinforcing ceramic body 14 that are adjacent to each other with the solid electrolyte plate 12 interposed therebetween.
It is formed on the side end surface which is different from 6 by 90 °.

Further, after the air electrode, the electrode for the fuel electrode are impregnated on the dice-shaped fired body and the electrode is formed, a current collector plate is attached. Since the cell 10 thus obtained is reinforced by the reinforcing ceramic body 14 even if the solid electrolyte plate 12 is thinned in order to reduce the internal resistance of the solid electrolyte plate 12, the mechanical strength etc. Well maintained. Therefore, handling of the cell 10 can be facilitated. Also,
By inserting the cell 10 into the fuel cell substrate 24, a solid oxide fuel cell can be easily formed, and the air supply groove 20 and the fuel supply groove 22 can be easily sealed.

[0016]

According to the present invention, the internal resistance of a cell for a solid oxide fuel cell can be lowered while maintaining the mechanical strength of the cell, and the cell can be easily handled. Moreover, since the sealing between the cells and the air supply groove is facilitated, it is possible to put the flat-plate solid oxide fuel cell into practical use.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of the present invention.

FIG. 2 is a partial cross-sectional view of the cell 10 shown in FIG.

FIG. 3 is an explanatory diagram illustrating a state in which a cell 10 is inserted into a fuel cell substrate.

FIG. 4 is an explanatory diagram illustrating a configuration of a conventional flat plate solid oxide fuel cell.

[Explanation of symbols]

 10 Cell for Solid Electrolyte Fuel Cell 12 Solid Electrolyte Plate 14 Reinforcing Ceramic Body 14a-14i Ceramic Layer 16 Airtight Layer

Claims (6)

[Claims] 1. A cell for a solid oxide fuel cell in which each of a plurality of solid electrolyte plates made of an ion conductive ceramic and formed in a dense structure is integrated through a reinforcing ceramic body, wherein the reinforcement is provided. The ceramic body is a ceramic body in which a plurality of ceramic layers having different thermal characteristics are laminated so that thermal characteristics such as a thermal expansion coefficient are sequentially changed to form an inclined structure, and the ceramic body is in contact with the solid electrolyte plate. The solid electrolyte fuel, wherein the thermal characteristics of the ceramic layer are similar to those of a solid electrolyte plate, and at least one of the ceramic layers is a porous layer through which a fluid such as air or fuel used in a fuel cell can pass. Battery cell. 2. The reinforcing ceramic body has an inclined structure in which the degree of porosity of each ceramic layer sequentially changes, the central layer located substantially at the center of the reinforcing ceramic body has the most porous structure, and a solid electrolyte plate. 2. The cell for a solid oxide fuel cell according to claim 1, wherein the ceramic layer in contact with is a dense structure similar to a solid electrolyte plate, and the ceramic layer in contact with the central ceramic layer is a porous structure close to a central layer. 3. A solid electrolyte comprising a reinforced ceramic body comprising a plurality of ceramic layers formed by mixing a ceramic component forming a solid electrolyte plate and a ceramic component forming a central layer having the most porous structure. The cell for a solid oxide fuel cell according to claim 2, wherein the composition of the ceramic layer in contact with the plate is close to that of the solid electrolyte plate, and the composition of the ceramic layer in contact with the center layer is similar to that of the center layer. 4. The solid electrolyte plate is a stabilized zirconia fired body obtained by adding a stabilizer such as yttria, and the central layer having the most porous structure is an alumina fired body. The solid electrolyte fuel cell described. 5. A plurality of solid electrolyte plate forming green sheets forming a solid electrolyte plate made of an ion conductive ceramic are laminated through a plurality of reinforcing ceramic green sheets forming a reinforcing ceramic body. During the production of the solid oxide fuel cell unit by firing, the distance from the central layer, which is the most porous ceramic layer located approximately in the center of the reinforcing ceramic body, to the ceramic layer that is in contact with the solid electrolyte plate. In order to be able to form a graded structure in which the composition of the composition sequentially changes, the ceramic component of the solid electrolyte plate forming green sheet and the ceramic component of the central layer forming green sheet forming the central layer are mixed to form a composition with each other. After forming a plurality of tilting green sheets having different thicknesses, the electrolyte plate forming green sheet and the central layer forming green sheet are formed. A plurality of inclining green sheets are sequentially laminated to form a laminated body so that the inclined structure is formed between the lean sheet and the lean sheet, and then the laminated body is formed into a dense solid electrolyte plate forming green sheet. A method for producing a cell for a solid oxide fuel cell, which comprises firing at a temperature equal to or higher than a denaturation temperature and equal to or lower than a densification temperature of a green sheet for forming a central layer. 6. A solid electrolyte plate forming green sheet is formed of zirconia to which a stabilizer such as yttria is added, a central layer forming green sheet is formed of alumina, and a plurality of tilting green sheets are formed. The method for producing a cell for a solid oxide fuel cell according to claim 5, which is formed by mixing zirconia added with a stabilizer such as yttria and alumina.