JP2007250266A - Solid oxide fuel cell stack and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solid oxide fuel cell stack which improves stability of power generation and reliability by substantially reducing a voltage loss and improving a yield in which an inter-connector in particular is concerned. <P>SOLUTION: In this solid oxide fuel cell stack, a plurality of cells composed of an anode 2, an electrolyte 3, and a cathode 5 are formed in this order on the surface of a support substrate 1 having a circulation part for fuel in its inside, and cells adjacent to each other are electrically connected in series through the inter-connector A. The inter-connector is formed by using a mixture containing flaky Ag powder and glass powder in the solid oxide fuel cell stack and in its manufacturing method. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a solid oxide fuel cell stack and a manufacturing method thereof.

  A solid oxide fuel cell (hereinafter abbreviated as “SOFC” where appropriate) generally has a high operating temperature of about 800 to 1000 ° C., but recently it is about 800 ° C. or less, that is, 800 to 650 ° C. Several operating temperatures are also being developed. The SOFC has an anode and a cathode arranged with an electrolyte material in between, and is composed of a three-layer unit of anode / electrolyte / cathode.

  During operation of the SOFC, electric power can be obtained by passing fuel to the anode side and passing an oxidant gas such as air to the cathode side and connecting both electrodes to an external load. However, since a single battery (hereinafter referred to as “cell”) can only obtain a voltage of about 0.8 V at most, it is necessary to electrically connect a plurality of cells in series in order to obtain practical power. There is. Interconnectors and cells are stacked alternately for the purpose of properly distributing, supplying, and discharging fuel and air to and from the anode and cathode respectively at the same time that adjacent cells are electrically connected in series. .

  The SOFC as described above is a type in which a plurality of cells are stacked, but a type of SOFC in which a plurality of cells are arranged in a horizontal stripe shape is also considered. The horizontal stripe method includes a cylindrical type (Japanese Patent Laid-Open No. 10-3932, hereinafter referred to as “932”) and a hollow flat type (WO 2004/082058 A1, WO 2004/088783 A1).

JP-A-10-3932 WO 2004/082058 A1 WO 2004/088783 A1

  FIG. 17 is a diagram showing a configuration example of a hollow flat type disclosed in WO 2004/082058 A1. 17A is a perspective view, FIG. 17B is a plan view, and FIG. 17C is a cross-sectional view taken along line AA in FIG. 17B. A plurality of cells 15 each including an anode 12, an electrolyte 13 and a cathode 14 are sequentially formed on a hollow flat insulator substrate 11, and each cell is electrically connected in series via an interconnector 16. . As shown by arrows (→) in FIGS. 17A and 17C, the fuel flows through the space in the insulating substrate 11, that is, the fuel flow portion 17 in parallel with the array of the cells 15. Note that the number of fuel circulation portions is not limited to one, and a plurality of flow passages may be provided, and the cross-sectional shape of the fuel circulation portion may be a rectangular shape (including a hollow flat shape), a rectangular shape, an elliptical shape, or the like.

  The interconnector electrically connects between the anode and cathode of adjacent cells, that is, between the anode of one cell and the cathode of the cell adjacent to the cell. Examples of the constituent material include the following (1 ) To (4). These materials are made into a slurry, for example, and a film is formed and dried to form an interconnector.

(1) A material whose main component is an oxide represented by the formula (Ln, A) CrO ₃ (wherein Ln is a lanthanoid and A is Ba, Ca, Mg or Sr).
(2) An oxide containing Ti, such as MTiO ₃ (wherein M is at least one element selected from Ba, Ca, Pb, Bi, Cu, Sr, La, Li, and Ce).
(3) A material mainly composed of Ag. In the case of this material, it is desirable to cover the interconnector made of this material with glass.
(4) A material composed of one or more of Ag, Ag wax, and a mixture of Ag and glass.

  From the viewpoints of the relationship between the thermal expansion coefficients of electrolyte materials, anode materials, and cathode materials, and the cost, the present inventors paid particular attention to composite materials containing Ag and glass, among these interconnector materials. We are continuing experiments and developments toward the realization. For example, in Japanese Patent Application No. 2005-5752 (filed on Jan. 12, 2005, hereinafter referred to as “752 application”), there is a problem in durability when only a composite material containing Ag and glass is used. However, the durability is improved by forming an intermediate layer made of a composite material containing Ag and Ni between the anode and the interconnector material.

Application for Japanese Patent Application No. 2005-5752

On the other hand, with regard to the composite material itself containing Ag and glass, it was observed that this mixture material had a low yield, a large voltage loss, and became unstable. This composite material may contain ZrO _{2 and} other trace components, but since it has such a simple composition, there is usually no room for further pursuit and it is considered to be a limit.

  Nevertheless, the present inventors further pursued the composite material itself containing Ag and glass, and experimented by thinking whether there was any improvement factor in the shape of the Ag component in the mixture. That is, the Ag component in this mixture is usually mixed in a spherical or granular form, but an experiment was attempted by changing the Ag component into various shapes. Then, by chance, it was found that when flaky Ag powder was used as the Ag component, the voltage loss could be greatly improved and the yield could be greatly improved.

  That is, the present invention greatly improves voltage loss and yield by using flaky Ag powder as an Ag component of an interconnector in a solid oxide fuel cell stack using a mixture of Ag and glass as an interconnector material. It is an object of the present invention to provide a solid oxide fuel cell stack and a method for producing the same.

  In the present invention, a plurality of cells including an anode, an electrolyte, and a cathode are sequentially formed on the surface of a support substrate having a fuel circulation portion therein, and adjacent cells are electrically connected in series via an interconnector. It is a solid oxide fuel cell stack formed by connection. And the said interconnector is formed using the mixture containing flaky Ag powder and glass powder, It is characterized by the above-mentioned.

  In the present invention, a plurality of cells including an anode, an electrolyte, and a cathode are sequentially formed on the surface of a support substrate having a fuel circulation portion therein, and adjacent cells are electrically connected in series via an interconnector. It is a solid oxide fuel cell stack formed by connection. And while arrange | positioning the intermediate | middle layer which consists of a composite material containing Ag and Ni between the anode and interconnector of an adjacent cell, the said interconnector is formed using the mixture containing flake-shaped Ag powder and glass powder It is characterized by being made.

  In the present invention, a plurality of cells including an anode, an electrolyte, and a cathode are sequentially formed on the surface of a support substrate having a fuel circulation portion therein, and adjacent cells are electrically connected in series via an interconnector. It is a manufacturing method of the solid oxide fuel cell stack formed by connection. And in the production, the interconnector which consists of a composite material containing flaky Ag powder and glass powder is arranged as the interconnector material.

  In the present invention, a plurality of cells including an anode, an electrolyte, and a cathode are sequentially formed on the surface of a support substrate having a fuel circulation portion therein, and Ag is formed as an intermediate layer between the anode and interconnector of adjacent cells. A composite material containing Ni and Ni is disposed, and an interconnector made of a composite material containing Ag and glass is disposed so as to cover the upper surface and the electrolyte, thereby producing a solid oxide fuel cell stack. And in the production, the interconnector which consists of a composite material containing flaky Ag powder and glass powder as a composite material containing Ag and glass is arranged.

  According to the present invention, in the SOFC stack, by using a composite material containing flaky Ag powder and glass powder as the interconnector material, the voltage loss in the SOFC stack is greatly improved, and the yield, that is, between cells. Interconnectors with low voltage loss can be formed with good reproducibility. Thereby, the stability and reliability of power generation by the SOFC stack can be improved.

  In the present invention, in the composite material constituting the interconnector, it is important to use flaky Ag powder as the Ag component mixed with the glass powder. All or most of the Ag component should be flaky, but if it contains a significant amount of flaky Ag powder to improve voltage loss in SOFC, it will contain granular or other forms of Ag. May be. In the Ag component, the ratio of the flaky Ag powder is preferably at least 20% or more, more preferably 60% or more.

The composite material may contain ZrO ₂ and other trace components. In the present specification, “composite material containing flaky Ag powder and glass powder” or “mixture containing flaky Ag powder and glass powder” is a trace component of flaky Ag powder and glass powder. It also means that it contains. The ratio of the flaky Ag powder to the glass powder, that is, the ratio of flaky Ag to glass, “flaked Ag: glass”, is preferably in the range of 3: 7 to 9: 1 by weight. In this composite material, flaky Ag, which is an electrically conductive material, is mixed in order to pass an electric current through glass, which is an insulator, and the mixture is used as a constituent material of the interconnector A.

The type of glass used in the present invention is not particularly limited. The glass contains K ₂ O, ZnO, BaO, Na ₂ O, CaO or the like in a network structure containing SiO ₂ or Al ₂ O ₃ in addition thereto, such as soda glass, borosilicate glass, Quartz glass and the like can be appropriately selected and used. As its characteristics, it is desirable that the glass has a thermal expansion coefficient in the range of 6.0 to 14.0 × 10 ⁻¹ / K and that the softening point is in the range of 600 ° C. to 1000 ° C. In addition to Ag itself, Ag includes, for example, an Ag-containing alloy such as an Ag—Pd alloy or a metal brazing material containing Ag. Any of these Ag materials are flaked and mixed with glass.

  Here, JP-A-6-223615 describes a conductive feeler made of a scaly Ag-Pt alloy, and JP-A-8-161929 discloses a conductive material in which a flaky copper powder is coated with silver, A conductive material containing a flaky Cu powder coated with Ag and a flaky Ag powder is described. However, these are not applied as flaky Ag powder alone as a conductive component, as in the present invention, and are not applied as a mixture with glass powder, and also operate at a high temperature of 650 to 1000 ° C. It cannot be applied as a component of a special or specific member called an interconnector.

Moreover, in those prior arts, these conductive materials are applied to polymer, paint, or electric circuit formation to prevent migration, that is, electrodeposition or oozing of the Ag component that occurs in Ag powder, scaly Ag powder, etc. These polymers, paints, electrical circuits, etc. are used at room temperature and in a single atmosphere (normal living environment).
On the other hand, the flaky Ag component in the SOFC of the present invention is a component of a special and specific member called an SOFC interconnector that is used repeatedly from normal temperature to high temperature and from high temperature to normal temperature with start-up-operation-stop It is used in harsh environments such as hydrogen and oxygen atmospheres with operating temperatures of 650 ° C or higher, especially 700 ° C or higher, ensuring surface conductivity at such high temperatures and improving voltage loss in SOFC. To do.

JP-A-6-223615 JP-A-8-161929

  FIG. 1A to FIG. 1C are diagrams for explaining an example of an SOFC stack according to the present invention, and are cross-sectional views of two adjacent cells among a plurality of cells arranged at intervals. It is shown as a diagram. In FIG. 1A, 1 is a support substrate, 2 is an anode, 3 is an adjacent electrolyte, and A is an interconnector. In the embodiment shown in FIG. 1A, an interconnector A is provided between the anode and cathode of adjacent cells.

  In the embodiment of FIG. 1B, the intermediate layer B is provided between the anode of the adjacent cell and the interconnector A. The technique of providing the intermediate layer B is related to the aforementioned 752 application, and in the embodiment as shown in FIG. 1A, when a composite material containing Ag and glass is used as the material of the interconnector, the durability is improved. When there was a problem, by placing the intermediate layer B between the anode and the interconnector A as shown in FIG. 1B, the durability was dramatically improved, and the stability and reliability of power generation were improved. Can be improved.

As a constituent material of the intermediate layer B, a composite material containing Ag and Ni is used. This composite material may contain ZrO ₂ and other trace components. In the composite material containing Ag and Ni, when NiO is used as the Ni raw material, the blending ratio of Ag and NiO is preferably in the range of 5: 5 to 1: 9. NiO is reduced to Ni in the working atmosphere of SOFC.

  The intermediate layer B may have two layers. Moreover, stability can be improved by heat-treating the intermediate layer B in advance. The intermediate layer B is also an interconnector, and the adjacent cells are electrically connected by an interconnector including the interconnector B and the interconnector A that are the intermediate layers. In addition, FIG.1 (c) shows the flow direction of the electric current at the time of the action | operation as SOFC for the example of Fig.1 (a).

  2 to 3 are diagrams illustrating a process of forming the SOFC stack of FIG. 2 shows the case of the embodiment of FIG. 1A, and FIG. 3 shows the case of the embodiment of FIG. 2 to 3, the same members and portions as those in FIG. 1 are denoted by the same reference numerals. First, as shown in FIG. 2, the support substrate 1 is prepared, and the anode 2 is disposed on the upper surface thereof. This stage is shown in FIG. Next, the electrolytes 3 and 3 are arranged on the surface of the anode 2 at intervals, and the recesses 4 are formed between the electrolytes 3 and 3. This stage is shown in FIG.

  Next, cathodes 5 and 5 are disposed on the surfaces of the electrolytes 3 and 3. This stage is shown in FIG. Then, the interconnector A is formed by arranging a composite material containing flaky Ag powder and glass powder from the recess 4 to the cathode. FIG. 2E shows this stage and corresponds to FIG.

  FIG. 3 shows the case of the embodiment of FIG. 1 (b), but the steps of FIGS. 3 (a) to 3 (d) are the same as the steps of FIGS. 2 (a) to (d). An interconnector B as an intermediate layer is formed by arranging a composite material containing Ag and Ni in the recess 4. FIG. 3E shows this stage. The interconnector B, which is an intermediate layer, is provided on the upper surface of the anode 2 of the adjacent cell and between the electrolytes 3 and 3 of the adjacent cells in the positional relationship between the anode and the electrolyte. Then, the interconnector A is formed by arranging a composite material containing flaky Ag powder and glass powder on the upper surface. FIG. 3 (f) shows this stage and corresponds to FIG. 1 (b).

  The present invention is applicable to any SOFC of a type in which a plurality of cells are arranged adjacent to each other at intervals. For example, in the case of a type of SOFC in which a plurality of cells are arranged in a horizontal stripe shape, the hollow flat type SOFC as shown in FIG. 17 is not limited, and a cylindrical type (for example, the above-mentioned 932 gazette) can be used. The present invention can be applied to any type provided with a support substrate having a fuel circulation part. In addition, the fuel circulation section is not limited to a single flow passage, and may have a plurality of flow paths, and the cross-sectional shape thereof may be any of a rectangular shape (including a hollow flat shape), a rectangular shape, other polygonal shapes, an elliptical shape, and the like. Also applies.

As a constituent material of the support substrate, a mixture of MgO and MgAl ₂ O ₄ , a zirconia-based oxide, a mixture of zirconia-based oxide and MgO and MgAl ₂ O ₄ , or the like can be used, but is not limited thereto. Among them, a mixture of MgO and MgAl ₂ O ₄ is preferably a mixture of MgO contained 20～70Vol% of the total amount of MgO and MgAl ₂ O _4. Examples of zirconia-based oxides include yttria-stabilized zirconia [YSZ: (Y ₂ O ₃ ) _X (ZrO ₂ ) _1-X (where x = 0.03 to 0.12)]. It is done.

As a constituent material of the anode, for example, a material containing Ni as a main component, a ceramic material containing a metal, or the like is used, but is not limited thereto. Among the ceramic materials containing metals, examples of the ceramic material include yttria-stabilized zirconia [YSZ: (Y ₂ O ₃ ) _X (ZrO ₂ ) _1-X (where x = 0.05 to 0.15)]. As the metal, at least one metal selected from Ni, Cu, Fe, Ru, and Pd, that is, one or more of these metals is used.

Among these ceramic materials containing metal, YSZ containing Ni (Ni—YSZ cermet), that is, Ni and (Y ₂ O ₃ ) _X (ZrO ₂ ) _1-X (wherein x = 0.05 to 0.15) ) Is a preferable anode material in the present invention, and in particular, it is preferable that Ni in the mixture is dispersed in an amount of 40 vol% or more.

The constituent material of the electrolyte may be a solid electrolyte having ionic conductivity, and examples thereof include the following materials (1) to (4), but are not limited to these exemplified materials.
(1) Yttria-stabilized zirconia [YSZ: (Y ₂ O ₃ ) _X (ZrO ₂ ) _1-X (where x = 0.05 to 0.15)].
(2) Scandia-stabilized zirconia [(Sc ₂ O ₃ ) _X (ZrO ₂ ) _1-X (where x = 0.05 to 0.15)].
(3) Yttria-doped ceria [(Y ₂ O ₃ ) _X (CeO ₂ ) _1-X (where x = 0.02 to 0.4)].
(4) Gadria-doped ceria [(Gd ₂ O ₃ ) _X (CeO ₂ ) _1-X (where x = 0.02 to 0.4)].

  EXAMPLES Hereinafter, although this invention is demonstrated in more detail based on an Example, it cannot be overemphasized that this invention is not limited to an Example.

Example 1
The following simulated SOFC cells (1) to (5) were prepared, and performance tests were performed on these simulated SOFC cells.
(1) A simulated SOFC cell provided with an interconnector material made of spherical Ag + glass. The test using this simulated cell is referred to as Comparative Example 1.
(2) A simulated SOFC cell having an interconnector B which is an intermediate layer and provided with an interconnector material made of spherical Ag + glass. A test using this simulated cell is referred to as Comparative Example 2. The simulated cell having the interconnector B as the intermediate layer corresponds to the prior art simulated cell according to the aforementioned 752 application.
(3) A simulated SOFC cell provided with an interconnector made of flaky Ag + glass. A test using this simulated cell is referred to as Example 1.
(4) A simulated SOFC cell provided with an interconnector made of flaky Ag + glass. A test using this simulated cell is referred to as Example 2. In the simulated cells of Example 1 and Example 2, flaky Ag powder is used as a raw material, but the type is different.
(5) A simulated SOFC cell having an interconnector B which is an intermediate layer and provided with an interconnector made of flaky Ag + glass. A test using this simulated cell is referred to as Example 3.

<Production of Simulated Cell of Comparative Example 1>
FIG. 4 is a view showing a cross section of the simulation cell of Comparative Example 1. Ni-YSZ cermet was prepared as an anode layer material. It is a member shown as 2 in FIG. On the surface of the anode layer, a space was provided at the center thereof, and an electrolyte composed of YSZ was disposed on both the left and right sides thereof. It is a member shown as 3 and 3 in FIG. A recess corresponding to the above-described interval is formed between the electrolytes 3 and 3 on both the left and right sides.

Next, a paste of a mixture of spherical Ag powder and glass powder was applied to the recess and dried to form an interconnector A. In this paste, a spherical Ag powder and a glass powder (SiO ₂ —SrO—K ₂ O—Na ₂ O-based bonding material, manufactured by Asahi Glass Co., Ltd.) are mixed in an organic solvent (a mixed solvent of toluene and 2-propanol) at a weight ratio of 7: 3. It was prepared by mixing in a mortar at a ratio of The organic solvent and glass powder used in forming the interconnector A described below are the same as the mixed solvent and glass powder.

<Production of Simulated Cell of Comparative Example 2>
FIG. 5 is a view showing a cross section of the simulation cell of Comparative Example 2. The arrangement of the anode layer and the electrolyte is the same as that of the simulation cell of Comparative Example 1 including the constituent materials. A recess is formed between the electrolytes 3 and 3 on both the left and right sides. The interconnector B was formed by applying a slurry of a mixture of spherical Ag powder and NiO powder to the recess and drying. A slurry of a mixture of spherical Ag powder and NiO powder is prepared by mixing spherical Ag powder and NiO powder in an organic solvent at a weight ratio of 5: 5 with a ball mill. NiO is reduced to Ni in the working atmosphere of SOFC.

  Thereafter, a paste of a mixture of spherical Ag powder and glass powder was applied to the upper surface of the interconnector B which is the intermediate layer and the electrolytes 3 and 3 on the left and right sides, and dried to form the interconnector A. The paste of the mixture of spherical Ag powder and glass powder is prepared by mixing spherical Ag powder and glass powder in an organic solvent at a weight ratio of 7: 3 in a mortar.

<Production of Simulated Cell of Example 1>
FIG. 6 is a diagram showing a cross section of the simulation cell of Example 1, and the drawing is the same as that of the simulation cell of Example 2 described later. The arrangement of the anode layer and the electrolyte is the same as that of the simulation cell of Comparative Example 1 including the constituent materials. A recess is formed between the electrolytes 3 and 3 on both the left and right sides. Next, a paste of a mixture of flaky Ag powder (Mitsui Metal Mining Co., Ltd.) and glass powder was applied to the recess and dried to form an interconnector A. The paste of a mixture of flaky Ag powder and glass powder is prepared by mixing flaky Ag powder and glass powder together with an organic solvent in a mortar at a weight ratio of 7: 3.

  FIG. 7 is a photomicrograph of the flaky Ag powder used here, and FIG. 8 is a diagram illustrating the photomicrograph of FIG. As shown in FIGS. 7 to 8, nearly spherical particles are mixed, but flaky particles having a diameter of 10 μm or more occupy about 46% of the whole.

<Production of Simulated Cell of Example 2>
FIG. 6 is a diagram showing a cross section of the simulated cell of the second embodiment, and the drawing is the same as the simulated cell of the first embodiment. The arrangement of the anode layer and the electrolyte is the same as that of the simulation cell of Comparative Example 1 including the constituent materials. A recess is formed between the electrolytes 3 and 3 on both the left and right sides.

  Next, a paste of a mixture of flaky Ag powder (manufactured by Fukuda Metal Foil Powder Industry Co., Ltd.) and glass powder was applied to the recess and dried to form an interconnector A. This paste of a mixture of flaky Ag powder and glass powder is prepared by mixing flaky Ag powder and glass powder together with an organic solvent in a mortar at a weight ratio of 7: 3.

<Production of Simulated Cell of Example 3>
FIG. 5 is a diagram showing a cross section of the simulation cell of Example 3, and the drawing is the same as the simulation cell of Comparative Example 2. And when forming the interconnector A, it carried out similarly to the simulation cell preparation of the comparative example 2 except having replaced the spherical Ag powder in the preparation of the simulation cell of the comparative example 2 with the flaky Ag powder (manufactured by Mitsui Mining & Mining Co., Ltd.). The simulated cell of Example 3 was produced.

<performance test>
The voltage loss was measured for each of the simulated cells produced as described above. FIG. 9 is a diagram illustrating a process in which each simulated cell is processed to be used for measurement. 9 shows the simulated cell of FIG. 4 as an example, but the same applies to the simulated cell of FIGS. As shown in FIG. 9C, the current collector 6 is disposed so as to cover the upper surface of the interconnector A in the simulated cell. Also, as shown in FIGS. 9A to 9C, a circular metal foil 7 is disposed on the peripheral upper surfaces of the electrolytes 3 and 3 in order to prevent mixing of hydrogen and air (oxygen) in the vicinity of the simulated cell.

  Each simulated cell thus processed was set in an electric furnace, and the presence or absence and the degree of voltage loss were measured for each. FIG. 10 shows an outline of the test apparatus. 8 is a heater of the electric furnace, 9 is an outer peripheral wall of the electric furnace, and a simulation cell is arranged in the center thereof. Then, as shown, a current generator and a voltage measuring device are set between the current collector 6 and the anode 2 of the simulated cell.

  The current generator is for flowing current from the outside. This test device is a device for measuring the presence / absence and degree of voltage loss in the interconnector, and is a mechanism for measuring the voltage loss when a current is passed.

In this performance test, hydrogen was supplied to the anode side, air was supplied to the interconnector side, the operating temperature was 700 ° C., and the current density was kept constant at 0.8 A / cm ² . 11 to 15 are diagrams showing the results. 11 to 15, the horizontal axis represents time (h) and the vertical axis represents voltage loss (V). The higher this voltage (V), the worse the performance of the cell.

<Test Results of Simulated Cell of Comparative Example 1>
11 to 12 are actual measurement values for the simulation cell of Comparative Example 1. FIG. FIG. 12 expands the horizontal axis and the vertical axis of FIG. 11 to make it easier to understand the vertical relationship of the measured voltage value for each elapsed time. As shown in FIGS. 11 to 12, the loss voltage rises and falls every measurement time with a center of 0.20V. Since the voltage of one cell is usually about 0.8V at most, the voltage loss of 0.20V is a considerable loss.

<Test Results of Simulated Cell of Example 1>
FIG. 13 shows measured values for the simulated cell of Example 1, and also shows data of the simulated cell of Comparative Example 1 in FIG. 11 described above. As shown in FIG. 13, the loss voltage of the simulated cell of Example 1 is about 0.015 V from the beginning of the measurement, which is much smaller than the loss voltage of the simulated cell of Comparative Example 1. Further, the loss voltage of the simulated cell of Example 1 hardly changes even after 100 hours.

<Test Results of Simulated Cell of Example 2>
FIG. 14 shows measured values for the simulated cell of Example 2 and also shows data of the simulated cell of Comparative Example 1 of FIG. As shown in FIG. 14, the loss voltage of the simulation cell of Example 2 is about 0.015 V from the beginning of measurement, and there is almost no change even after 20 hours.

<Test Results of Simulated Cell of Comparative Example 2 and Simulated Cell of Example 3>
FIG. 15 shows measured values for the simulation cell of Comparative Example 2 (with an intermediate layer) and the simulation cell of Example 3 (with an intermediate layer). The data of the simulation cell (no intermediate layer) of Example 1 in FIG. 13 is also shown. As shown in FIG. 15, the loss voltage in the simulation cell of Comparative Example 2 having an intermediate layer and using spherical Ag as the constituent material of the interconnector A slightly increases and decreases from the start of measurement until 2 hours elapse. After that, there is almost no change at 0.008V.

  On the other hand, the loss voltage in the simulated cell of Example 3 having the intermediate layer and using flaky Ag as the constituent material of the interconnector A is 0.006 V when 4 hours elapse, and gradually increases with time. It becomes smaller, and it becomes smaller to 0.001V after 14 hours. The value is maintained even after 20 hours. Thus, the loss voltage in the simulation cell of Example 3 is much smaller than the loss voltage of the simulation cell of Comparative Example 2.

  Further, the loss voltage of the simulation cell (without intermediate layer) of Example 1 shown in FIG. 15 is as compared with the loss voltage of the simulation cell (without intermediate layer) of Comparative Example 1 as apparent from FIG. An order of magnitude improvement. Still, it has a middle layer and is larger than the loss voltage in the simulation cell of Comparative Example 2 using spherical Ag as the constituent material of the interconnector A. This is understood that the intermediate layer, that is, the interconnector B contributes to the reduction of the loss voltage.

  And as the simulation cell of Example 3, it has an intermediate | middle layer and uses a flaky Ag as a constituent material of the interconnector A, In addition to the fall of the loss voltage in an intermediate | middle layer, it aims at the fall of a loss voltage further It shows that you can.

Example 2
Samples of the following (1) to (2): A plurality of disk-shaped molded bodies were prepared, and the surface resistance of each was measured.
(1) A disk-shaped molded body made of an interconnector material made of spherical Ag + glass.
(2) A disk-shaped molded body made of an interconnector material made of flaky Ag + glass.

  The disk-shaped molded body of (1) was produced by molding into a disk shape using the same mixed powder of spherical Ag powder and glass powder as used in the comparative example simulation cells 1 and 2. The disk-shaped molded body of (2) was produced by molding into a disk shape using the same mixed powder of flaky Ag powder and glass powder as used in the example simulation cell 1.

<Measurement of surface resistance>
Each disk-shaped molded body of (1) and (2) was put in an electric furnace. Then, the temperature was raised with a heater of an electric furnace, for example, after firing under a firing condition of 500 ° C. for 2 hours, taken out from the furnace, a tester was set as shown in FIG. Table 1 shows the firing conditions (temperature, time) and the measurement results.

  As shown in Table 1, after baking at 500 ° C. for 2 hours, the surface resistance of both “spherical Ag + glass” and “flaked Ag + glass” is 0.1Ω or less and does not change. After firing at 700 ° C. for 2 hours, the surface resistance of “spherical Ag + glass” shows a value of 0.2-1.0Ω, whereas the surface resistance of “flaky Ag + glass” varies below 0.1Ω. Absent. When firing at 700 ° C. for 50 hours, the surface resistance of “spherical Ag + glass” becomes 0.01 MΩ or more, and the conductivity becomes zero. On the other hand, the surface resistance of “flaky Ag + glass” is 0.1Ω or less and maintains a high electrical conductivity. The surface resistance of “flaky Ag + glass” does not change even after baking at 900 ° C. for 2 hours.

The figure explaining the example of an aspect of the SOFC cell stack concerning this invention The figure explaining the process of forming the SOFC stack of Fig.1 (a) The figure explaining the process of forming the SOFC stack of FIG.1 (b). The figure which shows the simulation cell of the comparative example 1 The figure which shows the simulation cell of the comparative example 2, and the simulation cell of Example 3 The figure which shows the simulation cell of Example 1, and the simulation cell of Example 2. Micrograph of flaky Ag powder used in the simulated cell of Example 1 Fig. 7 is a micrograph of the flaky Ag powder of Fig. 7 Diagram explaining the process of processing each simulated cell for measurement The figure which shows the outline of the test equipment which measured voltage loss as a performance test The figure which shows the measurement result of the voltage loss of the simulation cell of the comparative example 1 The figure which shows the measurement result of the voltage loss of the simulation cell of the comparative example 1 The figure which shows the measurement result of the voltage loss of the simulation cell of Example 1. The figure which shows the measurement result of the voltage loss of the simulation cell of Example 2. The figure which shows the measurement result of the voltage loss of the simulation cell of the comparative example 2, and the simulation cell of Example 3. The figure which shows the measurement state of the surface electrical resistance after high temperature baking about "spherical Ag + glass" and "flaked Ag + glass" Diagram showing a configuration example of a hollow flat type horizontal stripe SOFC (prior art example)

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Support substrate 2 Anode 3 Electrolyte 4 Recessed part (becomes an intermediate layer)
5 Cathode A Interconnector B Intermediate layer (interconnector)
DESCRIPTION OF SYMBOLS 5 Current collector 7 Metal foil 8 Electric furnace heater 9 Electric furnace outer peripheral wall 11 Hollow flat insulator board 12 Anode 13 Electrolyte 14 Cathode 15 Cell 16 Interconnector 17 Fuel distribution part

Claims (5)

  A plurality of cells composed of an anode, an electrolyte, and a cathode are sequentially formed on the surface of a support substrate having a fuel circulation portion therein, and adjacent cells are electrically connected in series via an interconnector. A solid oxide fuel cell stack, wherein the interconnector is formed using a mixture containing flaky Ag powder and glass powder.   A plurality of cells composed of an anode, an electrolyte, and a cathode are sequentially formed on the surface of a support substrate having a fuel circulation portion therein, and adjacent cells are electrically connected in series via an interconnector. In the solid oxide fuel cell stack, an intermediate layer made of a composite material containing Ag and Ni is disposed between an anode and an interconnector of an adjacent cell, and the interconnector includes flaky Ag powder and A solid oxide fuel cell stack formed using a mixture containing glass powder.   A plurality of cells composed of an anode, an electrolyte, and a cathode are sequentially formed on the surface of a support substrate having a fuel circulation portion therein, and adjacent cells are electrically connected in series via an interconnector. In producing a solid oxide fuel cell stack, an interconnector made of a composite material containing flaky Ag powder and glass powder is disposed as the interconnector material. Method.   A plurality of cells including an anode, an electrolyte, and a cathode are sequentially formed on the surface of a support substrate having a fuel circulation portion therein, and Ag and Ni are included as intermediate layers between the anode and the interconnector of adjacent cells. As a composite material containing Ag and glass, a composite material is disposed, and an interconnector made of a composite material containing Ag and glass is disposed so as to cover the upper surface and the electrolyte. A method for producing a solid oxide fuel cell stack, comprising providing an interconnector made of a composite material containing flaky Ag powder and glass powder. A material for an interconnector of a solid oxide fuel cell stack, comprising a composite material containing flaky Ag powder and glass powder.

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