JP2008053045A - Solid electrolyte fuel cell and manufacturing method thereof - Google Patents

Abstract

To provide a solid oxide fuel cell that can be co-fired easily, has little deterioration in conductivity, and can be realized at a low cost, and a method for manufacturing the same.
In a solid electrolyte fuel cell stack 1, a solid electrolyte body 7, a ceramic base 13 of an interconnector 5, and a ceramic base 21 of an outer connector 6 are formed of an Sc-stabilized zirconia solid solution having the same composition. The via 19 and the extraction electrode 23 are made of a conductor having the same composition, that is, a metal material of Ag—Pd (Pd: 30 mol%).
[Selection] Figure 1

Description

  The present invention relates to a solid oxide fuel cell having a solid oxide fuel cell and a connector, and a method for manufacturing the same.

Conventionally, a solid oxide fuel cell (hereinafter also referred to as SOFC) using a solid electrolyte (solid oxide) is known as a fuel cell.
In this SOFC, as a power generation unit, for example, a solid oxide fuel cell having a fuel electrode in contact with fuel gas on one side of a solid electrolyte body and an air electrode in contact with air on the other side is provided (SOFC cell). A solid oxide fuel cell stack (SOFC stack) in which a plurality of SOFC cells are stacked has been developed.

Further, in the SOFC stack, for example, a plate-like interconnector having conductivity is used in order to ensure conduction between cells or to separate gas flow paths between cells.
As the above-mentioned SOFC cell shape, a cylindrical shape, a flat plate shape, a monolith shape, and the like are known. Of these, the monolith type SOFC is a ceramic green sheet in which a solid electrolyte body and an interconnector are laminated. It is a so-called integrally sintered SOFC that is fired (see Patent Document 1).

This monolithic SOFC is considered to have an excellent stack structure because the connection reliability between cells is high and the gas sealing property is high.
However, in the case of a monolithic SOFC, the SOFC cell and the interconnector must be fired simultaneously, and it is important to match the firing temperatures of the materials. Therefore, the combination of materials that can be used has been limited.

For example, Patent Document 2 discloses a technique using lanthanum chromite for an interconnector. Further, in Cited Document 3, a conductive via is formed in a ceramic having no electronic conductivity to impart conductivity to the interconnector, and lanthanum manganite or NiO cermet is used as the conductive via. Further, in the cited document 4, Pt is used for the conductive via.
Japanese translation of PCT publication No. 6-502957 JP-A-6-68885 Japanese Patent Laid-Open No. 5-94828 JP 2003-132914 A

However, the above-described method using lanthanum chromite has a problem that simultaneous firing is difficult because lanthanum chromite is a hardly sinterable material.
In addition, the method of using lanthanum manganese nitrite or NiO cermet for the conductive via has a problem that the conductivity cannot be maintained in the long-term operation environment of SOFC because the conductivity of the same material decreases depending on the atmosphere.

Further, when the conductive via is a Pt via, there is a problem that Pt is expensive although Pt has almost no atmospheric dependency.
The present invention has been made in order to solve the above-described problems, and an object of the present invention is to provide a solid oxide fuel cell that can be co-fired easily, has little deterioration in conductivity, and can realize low cost, and a method for manufacturing the same. It is to provide.

  (1) The invention of claim 1 is a solid electrolyte fuel cell comprising a fuel electrode in contact with fuel gas, an air electrode in contact with oxidant gas, and a solid electrolyte body (oxygen ion conductive ceramics), and the solid electrolyte. A solid electrolyte fuel cell sintered integrally with the fuel cell, wherein the connector passes through its ceramic portion and is electrically connected to the fuel electrode or the air electrode. The via conductor provided with the connected via and filled in the via is made of an Ag—Pd-based metal material.

  The present invention relates to an integrally sintered solid electrolyte fuel cell (so-called monolithic SOFC). In the present invention, a connector penetrates an insulating ceramic portion and is connected between cells (or, for example, a cell and an external device). And) vias having conductivity are secured, and the via conductor filled in the vias is an Ag-Pd-based metal material.

That is, in the present invention, since the via conductor is an Ag—Pg metal, there is an advantage that the conductivity does not depend on the atmosphere, and the cost is lower than that of Pt alone.
In the present invention, since the solid oxide fuel cell is integrally sintered and integrated, it has a high sealing performance and does not require a sealing material as in the conventional assembly type.

  In addition, it is understood from the fact that the respective ceramic structures are continuously integrated in the solid electrolyte body and the ceramic portion (ceramic base) of the connector. In particular, when the solid electrolyte body and the ceramic portion of the connector are of the same type, the ceramic structures are usually completely the same and the interface disappears.

  A known material can be used as the material for the fuel electrode and the air electrode, but a metal material or a composite of a metal material and ceramics is particularly desirable. This is because cracks and warpage during firing can be suppressed by using a metal material.

  As the metal material, Pt, Pd, Ag, Au, Cu, Ni, W, Mo, Fe, Co, and alloys thereof can be used. Of these, Pt is particularly preferable. This is because Pt has a high melting point and can be easily co-fired with ceramics.

  When a composite of a metal material and ceramics is used, known ceramics such as alumina, silica, zirconia, ceria, calcia, magnesia, spinel and the like can be used. In particular, it is desirable that the same as the solid electrolyte body, since simultaneous firing can be easily performed and the electrode performance is improved.

  The via conductor may be a single Ag—Pd metal or a composite with ceramics. In the case of a composite with ceramics, known ceramics such as alumina, silica, zirconia, spinel and the like can be used. In particular, it is desirable that the same as the solid electrolyte body, since simultaneous firing can be easily performed.

In general, a solid oxide fuel cell stack in which a plurality of the solid electrolyte fuel cells are stacked is used as the solid electrolyte fuel cell.
(2) In the invention of claim 2, the Ag-Pd composition is characterized in that Pd is in the range of 20 to 40 mol% when the total metal of Ag-Pd is 100 mol%.

The present invention exemplifies a preferred composition of the Ag—Pd metal material.
The reason for this is that if the Pd content is less than 20 mol%, the melting point is low, and the metal may melt to form an electrode when integrally sintered with the material of the solid electrolyte body. . On the other hand, if the Pd content is more than 40 mol%, the alloy becomes expensive.

(3) The invention of claim 3 is characterized in that the solid electrolyte body is mainly composed of Sc-stabilized zirconia.
Sc-stabilized zirconia is suitable as a solid electrolyte because it has a low sintering temperature, high conductivity, and low reactivity with other materials. This Sc-stabilized zirconia is obtained by adding oxygen ion conductivity by dissolving Sc in zirconia.

  The Sc solid solution amount of Sc-stabilized zirconia can be 3 to 12 mol%, but 10 mol% is particularly preferable because of high oxygen ion conductivity. Moreover, elements other than Sc (for example, known elements such as Ce, Al, Gd) may be contained, and in particular, containing Ce is desirable because oxygen ion conductivity is stabilized.

(4) The invention of claim 4 is characterized in that the solid electrolyte body is a ceramic that can be sintered at 1050 to 1250 ° C.
As a result, it is possible to perform integrated sintering at a lower temperature than in the past. As the ceramics (oxygen ion conductive ceramics) that can be sintered at 1050 to 1250 ° C., YSZ (Y-stabilized zirconia), ScSZ (Sc-stabilized zirconia), added with a sintering aid such as Ga and Al, Examples thereof include GDC (Gd-doped Ce), SDC (Sm-doped Ce), and perovskite oxide.

(5) The invention of claim 5 is characterized in that the connector is a ceramic that can be sintered at 1050 to 1250 ° C.
As a result, it is possible to perform integrated sintering at a lower temperature than in the past. As this connector, alumina, silica, spinel, zirconia, glass ceramics or the like to which a sintering aid is added can be used. In particular, a material of the same kind as the solid electrolyte body is desirable because the thermal expansion coefficient is the same as the sintering temperature.

(6) The invention of claim 6 is characterized in that the connector is an interconnector for electrically connecting the solid oxide fuel cells.
The present invention illustrates a connector. The interconnector has, for example, a function of alternately stacking cells and separating and supplying oxidant gas and fuel gas to the cells and a function of connecting electricity generated by the cells between the cells. A gas flow path can be formed by the ceramic portion of the interconnector, and electrical conductivity is imparted by a conductor filled in the via (via conductor).

  (7) In the invention of claim 7, the connector is an outer connector for electrically connecting a solid oxide fuel cell disposed at an end of the solid oxide fuel cell and the outside. To do.

The present invention illustrates a connector. Thereby, for example, electricity can be easily taken out from the end of the stacking direction of the stack.
(8) The invention according to claim 8 is characterized in that the takeout electrode (electrode for taking out electricity from the battery) of the outer connector contains an Ag—Pd-based metal material as a main component.

In the present invention, since the Ag—Pd-based metal material is used as the extraction electrode of the outer connector, the conductivity is hardly lowered and the cost is low.
(9) The invention of claim 9 (a method for producing a solid electrolyte fuel cell) prints an electrode paste on the front and back of a ceramic green sheet for a solid electrolyte body that can be sintered at 1050 to 1250 ° C. and is not fired A solid electrolyte fuel cell is formed, and an Ag-Pd via conductor paste is filled in a through hole provided in a ceramic green sheet for a connector that can be sintered at 1050 to 1250 ° C. A connector is formed, the unfired solid electrolyte fuel cell and the unfired connector are laminated and pressure-bonded to form a laminate, and then the laminate is fired at 1050 to 1250 ° C. .

  In the case of a monolithic SOFC in which the solid electrolyte body and the connector are fired simultaneously, it is generally fired at 1300 ° C. or higher (for example, about 1400 ° C.). Only Pt is a metal that can withstand this firing temperature and does not oxidize even in an oxidizing atmosphere. In the case of producing a monolithic SOFC other than Pt, it is necessary to lower the firing temperature. However, if the firing temperature is lowered, it is difficult to obtain a dense solid electrolyte body or connector, and it is difficult to obtain a function as SOFC.

  In the present invention, as a material for the solid electrolyte body and the connector, a material that can be fired at a temperature lower than the conventional one is used. For example, by using Sc-stabilized zirconia, which has higher sinterability than Y-stabilized zirconia, or by increasing the specific surface area of the raw material powder, the firing temperature can be lowered. Material is used. This makes it possible to use an Ag—Pd-based metal material having a low melting point during simultaneous firing.

  Here, the firing temperature is 1050 to 1250 ° C. (preferably 1100 to 1200 ° C.), but if it is lower than 1050 ° C., it is difficult to sinter the solid electrolyte body and the connector, and Ag is 1250 ° C. or higher. This is because the melting point of the —Pd-based metal is exceeded and the via shape cannot be maintained.

By the production method of the present invention, the solid electrolyte fuel cell according to any one of claims 1 to 8 can be easily produced at a low firing temperature at a low cost.
When the ceramic green sheet for a solid electrolyte body is manufactured using powder as a raw material, when using Sc-stabilized zirconia, the powder of Sc-stabilized zirconia has a specific surface area (BET) of 5 to ²⁰ m ^2. / G (particularly 8 to 12 m ² / g) is desirable. This is because if the powder has a specific surface area that is too small, sintering is difficult to proceed, and conversely if the specific surface area is too large, it is difficult to produce a green sheet.

  In addition, the solid electrolyte body has ion conductivity that can move one part of the fuel gas introduced into the fuel electrode or the oxidant gas introduced into the air electrode as ions when the battery is operated. Have. Examples of the ions include oxygen ions and hydrogen ions. Further, the fuel electrode comes into contact with the fuel gas that becomes the reducing agent and functions as a negative electrode in the cell. The air electrode is in contact with an oxidant gas serving as an oxidant and functions as a positive electrode in the cell.

In the case where power generation is performed using the solid oxide fuel cell, a fuel gas is introduced to the fuel electrode side and an oxidant gas is introduced to the air electrode side.
As fuel gas, hydrogen, hydrocarbon as a reducing agent, mixed gas of hydrogen and hydrocarbon, fuel gas obtained by passing these gases through water at a predetermined temperature and humidified, and fuel obtained by mixing these gases with water vapor Gas etc. are mentioned. The hydrocarbon is not particularly limited, and examples thereof include natural gas, naphtha, and coal gasification gas. The fuel gas is preferably hydrogen. These fuel gas may use only 1 type and can also use 2 or more types together. Moreover, you may contain inert gas, such as nitrogen and argon of 50 volume% or less.

  Examples of the oxidizing gas include a mixed gas of oxygen and another gas. Further, the mixed gas may contain 80% by volume or less of an inert gas such as nitrogen and argon. Of these oxidant gases, air (containing about 80% by volume of nitrogen) is preferred because it is safe and inexpensive.

Next, an example of the best mode of the present invention will be described.
[Embodiment]
a) A configuration of a monolithic solid electrolyte fuel cell (specifically, a monolithic solid electrolyte fuel cell stack: monolithic SOFC stack) according to the present embodiment will be described with reference to FIG.

  FIG. 1 schematically shows a part of a solid oxide fuel cell stack in a cut-away state. Here, for simplification of explanation, a fuel gas flow path and an air flow path are provided. Shown in parallel.

  As shown in the figure, the solid oxide fuel cell stack 1 of the present embodiment receives power from a fuel gas (for example, hydrogen) and an oxidant gas (for example, air (specifically, oxygen in the air)) to generate power. It is a device to perform.

  In this solid oxide fuel cell stack 1, plate-like solid electrolyte fuel cell 3 as a power generation unit and plate-like interconnectors 5 that ensure conduction between cells 3 and block gas flow paths are alternately arranged. Further, the plate-like outer connectors 6 are laminated on both outer sides in the laminating direction and integrally sintered.

  Among them, the solid electrolyte fuel cell 3 has an air electrode (cathode) 9 formed on one side (upper side of the figure: front side) of the plate-like solid electrolyte body 7 and the other side (lower side of the figure). : On the back side) a fuel electrode (anode) 11 is formed.

  The interconnector 5 is provided with a concave fuel gas flow path 15 on the front side of the plate-shaped ceramic base 13 so as to cover the fuel electrode 11, and on the back side, a concave air flow path so as to cover the air electrode 9. 17 is provided. In this interconnector 5, a via 19 filled with a via conductor is formed so as to penetrate the ceramic base 13 (on both sides of the fuel gas passage 15 and the air passage 17) in the plate thickness direction. The via 19 electrically connects the fuel electrode 11 of the upper solid oxide fuel cell 3 and the air electrode 9 of the lower solid oxide fuel cell 3.

  Of the outer connectors 6, the upper outer connector 6 </ b> A is provided with a concave air flow path 17 on the lower side (cell side) of the plate-shaped ceramic base 21 </ b> A so as to cover the air electrode 9. An extraction electrode 23A that is electrically connected to the outside is provided (outside in the stacking direction). The outer connector 6A is formed with a via 19 filled with a via conductor so as to penetrate the ceramic base 21A in the plate thickness direction. By the via 19, the air electrode of the lower solid oxide fuel cell 3 is formed. 9 and the extraction electrode 23A are electrically connected.

  On the other hand, the outer connector 6B on the lower side of the figure is provided with a concave fuel gas channel 15 on the upper side (cell side) of the plate-like ceramic base 21B so as to cover the fuel electrode 11, and on the lower side (outside in the stacking direction). In addition, an extraction electrode 23B is provided. A similar via 19 is also formed in the outer connector 6B. The via 19 electrically connects the fuel electrode 11 of the upper solid oxide fuel cell 3 and the extraction electrode 23B.

  In particular, in the present embodiment, the solid electrolyte body 7, the ceramic base 13 of the interconnector 5, and the ceramic bases 21A and 21B (generally referred to as 21) of the outer connector 6 are formed of Sc-stabilized zirconia solid solution having the same composition. In addition, the via 19 and the extraction electrodes 23A and 23B (collectively referred to as 23) are made of a conductor having the same composition, that is, a metal material of Ag—Pd (Pd: 30 mol%).

  In this embodiment, since the solid electrolyte fuel cell stack 1 is integrally sintered, the solid electrolyte body 7, the ceramic base 13 of the interconnector 5, and the ceramic base 21 of the outer connector 6 are mutually connected. The ceramic structure is continuously integrated.

  b) When manufacturing the above-described solid electrolyte fuel cell stack 1, as described in detail later in the examples, on the front and back of the ceramic green sheet for the solid electrolyte body that can be sintered at 1050 to 1250 ° C., An electrode paste is printed to form an unfired solid oxide fuel cell, and an Ag-Pd-based via conductor is formed in a through hole provided in a ceramic green sheet for a connector that can be sintered at 1050 to 1250 ° C. A paste is filled in to form a green connector.

Then, the unfired solid electrolyte fuel cell and the unfired connector are laminated and pressed to form a laminate, and then the laminate is fired at 1050 to 1250 ° C.
c) In the solid electrolyte fuel cell stack 1 of the present embodiment thus obtained, the solid electrolyte body 3, the ceramic substrate 13 of the interconnector 5, and the ceramic substrate 21 of the outer connector 6 are at 1050 to 1250 ° C. It is composed of Sc-stabilized zirconia, which is a ceramic that can be sintered.

  In addition, vias 19 are formed in the ceramic substrate 13 of the interconnector 5 and the ceramic substrate 21 of the outer connector 6 so as to pass through the ceramic substrates 13 and 21 and to ensure electrical connection between cells or between the cells and the outside. Yes. The via 19 is filled with Ag—Pd metal, and the extraction electrode 23 is also composed of Ag—Pd metal.

Therefore, it is not necessary to use expensive Pt for the via 19 or the extracted metal 23, and the integrated sintering can be sufficiently performed at a low temperature. Further, Ag—Pd metal has an advantage that the conductivity does not depend on the atmosphere.
[Experimental example]
Next, experimental examples of solid oxide fuel cells will be described.

In this experimental example, the following tests were conducted in order to investigate oxygen ion conductive ceramics (solid electrolyte bodies) that can be sintered at 1250 ° C. or lower.
(1) Preparation and Evaluation of Sinterability Evaluation Sample Powders having compositions and specific surface areas (BET) shown in Table 1 below were pressed into a cylindrical shape having a diameter of 15 mm and a height of 3 mm.

  This press body was fired at 1250 ° C. to prepare a sinterability evaluation sample. The water absorption and relative density {= (bulk density / theoretical density) × 100} of the obtained sample were measured. The results are shown in Table 1 below.

  From Table 1, the powders of Experimental Examples A to C became dense at 1250 ° C., but the powders of Experimental Examples D and E could not obtain a dense sintered body. The reason why a dense sintered body could not be obtained in Experimental Example D is considered that the firing temperature is low with this material, and the reason why a dense sintered body was not obtained in Experimental Example E is that the BET is small. Can be considered.

Next, an example of a solid oxide fuel cell will be described with reference to FIGS.
This embodiment is a monolithic SOFC (however, a simple sample) in which the solid electrolyte body of the solid electrolyte fuel cell (power generation cell) and the interconnector are made of the same zirconia solid solution.

  In this example, a simple sample of a monolithic SOFC was prepared by the following procedure, and the power generation test was performed. In this simple sample, the flow paths of air and fuel gas are not separated by the interconnector, but when the cells are actually stacked, the flow paths are separated by the interconnector.

(1) Preparation of green sheet Ce-added Sc-stabilized zirconia (solid solution) powder (10Sc1CeSZ), butyral resin, plasticizer and organic solvent are mixed to prepare a slurry, and the slurry is cast by a doctor blade method. A 10Sc1CeSZ green sheet having a thickness of 200 μm was produced.

(2) Preparation of electrodes and via paste Pt powder, 10Sc1CeSZ powder, ethylcellulose, and an organic solvent were mixed to prepare a Pt paste. Moreover, Ag-Pd (Pd: 30 mol%) powder, 10Sc1CeSZ powder, ethyl cellulose, and an organic solvent were mixed to prepare an Ag-Pd paste.

(3) Production of unsintered power generation cell As shown in FIG. 2, in order to form electrode patterns 25 to be the fuel electrode and the air electrode on the front and back of the 10Sc1CeSZ green sheet 24, Pt paste was printed in a 12 cm square shape. An unfired power generation cell 26 was produced.

(4) Production of unsintered interconnector 10 cm square gas through holes 31 and 33 that serve as gas flow paths are formed in 10Sc1CeSZ green sheets 27 and 29, and a φ0.25 mm through hole (via hole) that serves as a via around them. A plurality of 35 were formed. After that, the via hole 35 was filled and printed with an Ag—Pd paste (which becomes a via conductor) to produce an unfired via 37.

  Further, the sheet surface around the gas through holes 31 and 33 is printed with Ag-Pd paste to form a frame-shaped pattern 39, and via conductors are electrically connected to each other by the frame-shaped pattern 39, Unfired interconnectors 41 and 43 were produced.

(5) Lamination and firing The unsintered interconnectors 41 and 43 are laminated and bonded to the front and back of the unsintered power generation cell 25 to be integrated. At this time, the electrode pattern 23 of the unfired power generation cell 25, the gas through holes 31 and 33 of the unfired interconnectors 41 and 43, and the unfired via 37 are overlapped in the projection direction (the vertical direction in the figure), and The Ag—Pd paste printed around the gas through holes 31 and 33 was laminated so as to be exposed on the sample surface.

  This laminate was degreased at 250 ° C. and then fired at 1150 ° C. to prepare a simple sample of the monolithic SOFC 51 shown in FIG. The obtained sample was densified and no cracks could be confirmed.

  The monolithic SOFC 51 manufactured in this way has interconnectors 59 and 61 on both sides of a SOFC cell 58 comprising a solid electrolyte body 57 having an air electrode 53 and a fuel electrode 55, as shown in a broken view in FIG. It is provided. In addition, the interconnectors 59 and 61 are provided with an air flow path 63 in contact with the air electrode 53 and a fuel gas flow path 65 in contact with the fuel electrode 55 at the center, and around the air flow path 63 and the fuel electrode 55. Vias 67 and 67 are provided so as to surround each.

  Of these, the upper via 67 connects the air electrode 53 and the terminal 71 on the upper surface of the upper interconnector 59, and the lower via 69 is the terminal on the lower surface of the fuel electrode 55 and the lower interconnector 61. 73 is connected.

(6) Power generation evaluation A simple sample of the obtained monolithic SOFC 51 is obtained by using air as an oxidant gas on the front surface (air channel 63 side) and a dew point as a fuel gas on the back surface (fuel gas channel 65). It was set in a power generation evaluation apparatus (not shown) so that it could be exposed to 30 ° C. H ₂ gas.

The terminals were connected so that electricity could be taken out from the terminals 71 and 73 on the front and back of the upper and lower interconnectors 59 and 61.
As a result, it was confirmed that a power generation of 0.3 W / cm ² at 0.7 V was possible at 800 ° C.

  In addition, when the cross section of the solid electrolyte body 57 of the simple sample of the monolithic SOFC 51 and the ceramic portion of the interconnectors 59 and 61 was observed with a scanning electron microscope (magnification 2000 times), the ceramic structures of each other were continuous. It was united.

[Comparative Example 1]
In this comparative example, 10Sc1CeSZ in Example 1 was all replaced with Y-stabilized zirconia (8YSZ). Except that, in the same manner as in Example 1, a simple sample of the monolithic SOFC of Comparative Example (Not shown) was prepared.

The obtained sample was not densified, and the power generation characteristics could not be evaluated.
[Comparative Example 2]
In this comparative example, a sample was prepared by firing at 1400 ° C. the raw material processed in the same manner as in the comparative example 1. In addition, it is the same as that of the said comparative example 1 except baking temperature.

  Although the obtained sample was densified, the power generation characteristics could not be evaluated because the electrode portions of the via and the interconnector were disconnected.

This embodiment is a monolithic SOFC stack (multilayer monolithic SOFC) in which SOFC cells are stacked in multiple layers.
This multilayer monolithic SOFC can be manufactured by the following procedure.

(1) Preparation of Green Sheet As in Example 1, a 10 Sc1CeSZ green sheet having a thickness of 200 μm was prepared.

(2) Production of electrode and via paste Pt paste and Ag-Pd paste were produced in the same manner as in Example 1.
(3) Fabrication of unsintered power generation cell As shown in FIG. 4A, as in Example 1, the Pt paste was printed on the front and back of the 10Sc1CeSZ green sheet 81 to form the electrode pattern 83, and the unsintered A power generation cell 84 was produced. A broken line is a cut portion.

(4) Fabrication of an unfired interconnector As shown in FIGS. 4B to 4D, a 10Sc1CeSZ green sheet has 10 cm square gas through-holes 91 and 93 serving as gas flow paths, and vias around them. Two 10Sc1CeSZ green sheets 85 and 89 having through-holes (via holes) 95 and 99 each having a diameter of 0.25 mm were produced, and one 10Sc1CeSZ green sheet 87 having only via holes 97 was produced.

Thereafter, via holes 95 to 99 of all the green sheets 85 to 89 were filled and printed with an Ag—Pd paste to produce unfired vias 101 to 105.
Next, the green through holes 91 and 93 and the unfired vias 101 and 105 are formed so that the positions of the unfired vias 101 to 105 coincide with the front and back of the green sheet 87 made of only the unfired vias 103. The sheets 85 and 89 were laminated and pressure-bonded to produce an unfired interconnector 107 (see FIG. 4E).

(5) Lamination and firing The unsintered interconnectors 41 and 43 are laminated and bonded to the front and back of the unsintered power generation cell 25 to be integrated. At this time, the electrode pattern 23 of the unfired power generation cell 25, the gas through holes 31 and 33 of the unfired interconnectors 41 and 43, and the unfired via 37 are overlapped in the projection direction (the vertical direction in the figure), and The Ag—Pd paste printed around the gas through holes 31 and 33 was laminated so as to be exposed on the sample surface.

  This laminate was degreased at 205 ° C. and then fired at 1150 ° C. to prepare a simple sample of the monolithic SOFC 51 shown in FIG. The obtained sample was densified and no cracks could be confirmed.

  The monolithic SOFC 51 manufactured in this way has interconnectors 59 and 61 on both sides of a SOFC cell 58 comprising a solid electrolyte body 57 having an air electrode 53 and a fuel electrode 55, as shown in a broken view in FIG. It is provided. In addition, the interconnectors 59 and 61 are provided with an air flow path 63 in contact with the air electrode 53 and a fuel gas flow path 65 in contact with the fuel electrode 55 at the center, and around the air flow path 63 and the fuel electrode 55. Vias 67 and 67 are provided so as to surround each.

  Of these, the upper via 67 connects the air electrode 53 and the terminal 71 on the upper surface of the upper interconnector 59, and the lower via 69 is the terminal on the lower surface of the fuel electrode 55 and the lower interconnector 61. 73 is connected.

(6) Power generation evaluation A simple sample of the obtained monolithic SOFC 51 is obtained by using air as an oxidant gas on the front surface (air channel 63 side) and a dew point as a fuel gas on the back surface (fuel gas channel 65). It was set in a power generation evaluation apparatus (not shown) so that it could be exposed to 30 ° C. H ₂ gas.

The terminals were connected so that electricity could be taken out from the terminals 71 and 73 on the front and back of the upper and lower interconnectors 59 and 61.
As a result, it was confirmed that a power generation of 0.3 W / cm ² at 0.7 V was possible at 800 ° C.

  In addition, when the cross section of the solid electrolyte body 57 of the simple sample of the monolithic SOFC 51 and the ceramic portion of the interconnectors 59 and 61 was observed with a scanning electron microscope (magnification 2000), the ceramic structures of each were continuously integrated. It was.

[Comparative Example 1]
In this comparative example, 10Sc1CeSZ in Example 1 was all replaced with Y-stabilized zirconia (8YSZ). Except that, in the same manner as in Example 1, a simple sample of the monolithic SOFC of Comparative Example (Not shown) was prepared.

The obtained sample was not densified, and the power generation characteristics could not be evaluated.
[Comparative Example 2]
In this comparative example, a sample was prepared by firing at 1400 ° C. the raw material processed in the same manner as in the comparative example 1. In addition, it is the same as that of the said comparative example 1 except baking temperature.

  Although the obtained sample was densified, the power generation characteristics could not be evaluated because the electrode portions of the via and the interconnector were disconnected.

This embodiment is a monolithic SOFC stack (multilayer monolithic SOFC) in which SOFC cells are stacked in multiple layers.
This multilayer monolithic SOFC can be manufactured by the following procedure.

(1) Preparation of Green Sheet As in Example 1, a 10 Sc1CeSZ green sheet having a thickness of 200 μm was prepared.

(2) Production of electrode and via paste Pt paste and Ag-Pd paste were produced in the same manner as in Example 1.
(3) Fabrication of unsintered power generation cell As shown in FIG. 4A, as in Example 1, the Pt paste was printed on the front and back of the 10Sc1CeSZ green sheet 81 to form the electrode pattern 83, and the unsintered A power generation cell 84 was produced. A broken line is a cut portion.

(4) Fabrication of an unfired interconnector As shown in FIGS. 4B to 4D, a 10Sc1CeSZ green sheet has 10 cm square gas through-holes 91 and 93 serving as gas flow paths, and vias around them. Two 10Sc1CeSZ green sheets 85 and 89 having through-holes (via holes) 95 and 99 each having a diameter of 0.25 mm were produced, and one 10Sc1CeSZ green sheet 87 having only via holes 97 was produced.

Thereafter, via holes 95 to 99 of all the green sheets 85 to 89 were filled and printed with an Ag—Pd paste to produce unfired vias 101 to 105.
Next, the green through holes 91 and 93 and the unfired vias 101 and 105 are formed so that the positions of the unfired vias 101 to 105 coincide with the front and back of the green sheet 87 made of only the unfired vias 103. The sheets 85 and 89 were laminated and pressure-bonded to produce an unfired interconnector 107 (see FIG. 4E).

(5) Lamination and firing The unfired power generation cells 84 and the unfired interconnector 107 were alternately arranged and laminated and pressure-bonded to be integrated. At this time, the electrode pattern 83 of the unfired power generation cell 84 overlaps the gas through holes 91 and 93 and the unfired vias 101 to 105 of the unfired interconnector 107.

  Thereafter, the laminate is cut to a required size along the broken line in the figure to obtain an unfired multilayer monolithic SOFC, this laminate is degreased at 205 ° C., and then fired at 1150 ° C. 5 and the multilayer monolith type SOFC111 shown in FIG. 6 were produced.

  The multilayer monolithic SOFC 111 manufactured in this way is obtained by alternately stacking SOFC cells 119 made of a solid electrolyte body 117 having air electrodes 113 and fuel electrodes 115 and interconnectors 121.

  The interconnector 121 includes a pair of rectangular members 125 to 131 on both sides of a central plate-like member 123, and the air flow path 133 and fuel that are in contact with the air electrode 113 by these members 123 to 131. A fuel gas flow path 135 in contact with the electrode 115 is formed. A via 137 is formed so as to surround the air flow path 133 and the fuel electrode 135.

  As shown in FIG. 6, on both sides of the multilayer monolithic SOFC 111 in the stacking direction, outer connectors 139 for taking out the electric power generated in each cell 119 are arranged. A current extraction terminal 141 connected to the via 137 is formed on the surface.

  Needless to say, the present invention is not limited to the above-described embodiments, and can be implemented in various modes without departing from the scope of the present invention.

It is explanatory drawing which fractures | ruptures a part of solid oxide fuel cell stack of embodiment, and is shown typically. FIG. 3 is an explanatory diagram showing a manufacturing procedure for the solid oxide fuel cell of Example 1. FIG. 3 is an explanatory view showing the solid electrolyte fuel cell of Example 1 in a broken state. FIG. 6 is an explanatory diagram showing a manufacturing procedure of the solid oxide fuel cell stack of Example 2. 3 is an exploded perspective view showing a part of a solid oxide fuel cell stack of Example 2. FIG. FIG. 4 is an explanatory view showing a part of the solid oxide fuel cell stack of Example 2 in a broken state.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,111 ... Solid electrolyte fuel cell stack 3, 58, 119 ... Solid electrolyte fuel cell 5, 59, 61, 121, 121 ... Interconnector 7, 57, 117 ... Solid electrolyte body 9, 53, 113 ... Air Electrode 11, 55, 115 ... Fuel electrode 15, 65, 135 ... Fuel gas flow path 17, 63, 133 ... Air flow path 19, 67, 69 ... Via

Claims (9)

A solid electrolyte fuel cell comprising a fuel electrode in contact with the fuel gas, an air electrode in contact with the oxidant gas, and a solid electrolyte body;
A connector for ensuring conduction with the solid electrolyte fuel cell;
In a solid oxide fuel cell sintered integrally,
The connector includes a via that is electrically connected to the fuel electrode or the air electrode through its ceramic portion.
The solid oxide fuel cell according to claim 1, wherein the via conductor filled in the via is an Ag-Pd metal material.   2. The solid oxide fuel cell according to claim 1, wherein the composition of the Ag—Pd series is such that Pd is in a range of 20 to 40 mol% when the total metal of Ag—Pd is 100 mol%.   The solid electrolyte fuel cell according to claim 1 or 2, wherein the solid electrolyte body contains Sc-stabilized zirconia as a main component.   The solid electrolyte fuel cell according to any one of claims 1 to 3, wherein the solid electrolyte body is a ceramic that can be sintered at 1050 to 1250 ° C.   5. The solid oxide fuel cell according to claim 1, wherein the connector is a ceramic that can be sintered at 1050 to 1250 ° C. 6.   6. The solid oxide fuel cell according to claim 1, wherein the connector is an interconnector that electrically connects the solid oxide fuel cells.   6. The connector according to claim 1, wherein the connector is an outer connector that electrically connects a solid oxide fuel cell arranged at an end of the solid oxide fuel cell and the outside. A solid oxide fuel cell according to 1.   8. The solid oxide fuel cell according to claim 7, wherein the extraction electrode of the outer connector is mainly composed of an Ag-Pd metal material.   An electrode paste is printed on the front and back of the ceramic green sheet for a solid electrolyte body that can be sintered at 1050 to 1250 ° C. to form an unfired solid electrolyte fuel cell, and can be sintered at 1050 to 1250 ° C. A through-hole provided in a ceramic green sheet for a connector is filled with an Ag-Pd-based via conductor paste to form an unfired connector, and the unfired solid electrolyte fuel cell and the unfired connector are formed. A method for producing a solid oxide fuel cell, comprising: laminating and pressing a connector to form a laminate, and firing the laminate at 1050 to 1250 ° C.

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