JP2019125480A - Cell-to-cell connection member, cell for solid oxide type fuel battery, solid oxide type fuel battery, sofc mono-generation system, and sofc co-generation system - Google Patents

Abstract

To provide a cell-to-cell connection member of a cell for solid oxide fuel battery with high power generation performance.SOLUTION: A cell-to-cell connection member 1 includes: a metal base 11 constituted of alloy member containing Ti, Si, Al, using Fe and Cr as a main constituent; an oxide coating 13 formed on a surface of the metal base 11 and containing TiO, using CrOas a main constituent; and a conductive coating 12 formed on a surface of the oxide coating 13 and constituted of conductive ceramic material containing at least two types of Zn, Co, Mn.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an inter-cell connection member, a cell for a solid oxide fuel cell, a solid oxide fuel cell, an SOFC monogeneration system, and an SOFC cogeneration system.

  A cell for a solid oxide fuel cell (hereinafter referred to as “SOFC” as appropriate) has an air electrode bonded to one side of an electrolyte layer and a fuel electrode bonded to the other side of the electrolyte layer. The single cell is stacked and sandwiched by a pair of electron conductive inter-cell connecting members that exchange electrons with the air electrode or the fuel electrode. And in such a SOFC cell, for example, it operates at an operating temperature of about 700 ° C. to 900 ° C., and along with the movement of oxide ions from the air electrode side to the fuel electrode side through the electrolyte membrane, a pair of electrodes An electromotive force is generated between them, and the electromotive force can be taken out and used outside.

The inter-cell connecting member used in such a SOFC cell is manufactured using a stainless alloy material containing Fe and Cr, which are excellent in electron conductivity and heat resistance, as main components. However, Cr ₂ O _3, which is an oxidation resistant film, is formed on the metal base used for the SOFC cell under high temperature operating conditions. This oxide film is a high-resistance layer, and can reduce the power generation output of the fuel cell, react with the air electrode of the fuel cell by Cr evaporation (scattering), and significantly reduce the electrode performance, etc. There is a problem with

Patent Document 1 discloses that, in the case of performing a firing process of firing in a state in which an inter-cell connecting member manufactured using a metal base such as a stainless steel alloy containing Cr and an air electrode are fired, It is described that the formation of a Cr (VI) oxide is suppressed to suppress the formation of an oxide of Cr (VI). In order to make this Cr (VI) oxide suppressed state, an n-type semiconductor film (protection is formed of an oxide whose standard free energy of formation is WO ₃ or less) on the surface of the alloy or oxide before the baking treatment is performed It is described that the film formation process which forms a film | membrane is performed. As described above, SOFC can use inexpensive stainless steel as an alloy material in recent years by taking measures such as formation suppression of a Cr ₂ O ₃ oxide film and prevention of Cr scattering.

  In addition to Fe and Cr as main components, various elements are added to the stainless steel alloy used as the metal base in order to impart heat resistance and corrosion resistance. It has been reported that these trace amounts of additive elements form an oxide film-like region inside the metal substrate due to the oxygen potential in the vicinity of the interface between the metal substrate and the protective film formed on the surface thereof. (Non-Patent Document 1). In this document, it is reported that a composite oxide of Mn and Cr (a spinel compound) is formed inside a metal substrate. And, in the Cr rich composition, the complex oxide exists as a high resistance layer. In addition, when the metal base is configured using stainless steel containing Si and Al and Ti, Al, Si, Ti, etc. contained in the metal base are oxidized according to the Ellingham diagram, and the oxidation is high in the metal. When formed as a film, there is a concern that the electron conductivity in the metal substrate may be reduced, that is, the power generation performance may be reduced.

International Publication No. 2007/083627

Hideto Kurokawa et al., “Oxidation behavior of Fe-16 Cr alloy interconnect for SOFC under hydrogen potential gradient”, Solid State Ionics 168 (2004) 13-21

  The present invention has been made in view of the above problems, and an object thereof is to provide an inter-cell connecting member for a solid oxide fuel cell having high power generation performance, a cell for a solid oxide fuel cell, and A solid oxide fuel cell, an SOFC monogeneration system, and an SOFC cogeneration system are provided.

A characterizing feature of an inter-cell connection member according to the present invention for achieving the above object is a metal base composed mainly of Fe and Cr, and an alloy member containing Ti, Si, and Al;
An oxide film containing Cr ₂ O ₃ as a main component and containing TiO ₂ formed on the surface of the metal substrate;
And a conductive coating film formed of a conductive ceramic material containing at least two or more of Zn, Co, and Mn formed on the oxide film.
Here, it is preferable that the content of Ti in the oxide film is 0.9% by mass or more.

The present inventors have found that if TiO ₂ is contained in the oxide film existing between the metal base material forming the inter-cell connection member and the conductive coating film, the oxide film containing Cr ₂ O ₃ as the main component It was found that the electrical resistance decreased.
That is, according to the present characteristic configuration, the inter-cell connection member is formed on the surface of the metal base, and the metal base composed of an alloy member containing Fe and Cr as main components and containing Ti, Si, and Al. A conductive composed mainly of Cr ₂ O ₃ and an oxide film containing TiO ₂ , and a conductive ceramic material formed on the oxide film and containing at least two or more of Zn, Co and Mn. By providing the conductive coating film, the electric resistance of the inter-cell connection member can be reduced to realize a solid oxide fuel cell with high power generation performance.

  Another characteristic configuration of the inter-cell connecting member according to the present invention is that the content of Ti in the alloy member is 0.20 mass% or more.

  According to the said characteristic structure, when the content rate of Ti in an alloy member is 0.20 mass% or more, the content rate of Ti contained in the oxide film formed in the surface can be raised. As a result, the electrical resistance of the oxide film can be reduced.

  Another feature of the cell-to-cell connection member according to the present invention is that the conductive coating film is mainly composed of a metal oxide containing Zn, Mn and Co.

According to the above feature configuration, the protective film is mainly made of a metal oxide containing Zn, Mn and Co, so that the mismatch between the thermal expansion coefficient of the protective film and the thermal expansion coefficient of the base or the air electrode is small. It is preferable that the durability of the SOFC cell can be enhanced. It is further preferable that the protective film has Zn _x (Co _y Mn _(1-y) ) _(3-x) O ₄ (0 <x <1, 0 <y x (3-x) ≦ 2) as a main material. . Further, it is more preferable that the protective film contains ZnCoMnO ₄ as a main material.

  Yet another feature of the intercell connecting member according to the present invention is that the conductive coating film is formed by electrodeposition coating.

  According to the above feature configuration, a dense and strong protective film can be realized.

  The characterizing feature of the solid oxide fuel cell according to the present invention is that the inter-cell connecting member and the air electrode are joined.

  According to the above-mentioned characteristic configuration, since the cell-to-cell connecting member and the air electrode are joined to constitute the cell for the solid oxide fuel cell, the electric resistance of the cell-to-cell connecting member is largely reduced, and the power generation performance is achieved. It is possible to realize a high SOFC cell.

  The characterizing feature of the solid oxide fuel cell according to the present invention is that the solid oxide fuel cell is mounted.

  According to the above characteristic configuration, a solid oxide fuel cell with high power generation performance can be realized.

  The characterizing feature of the SOFC monogeneration system according to the present invention is that the solid oxide fuel cell is provided, and the electric power generated by the solid oxide fuel cell is supplied to the electric load.

  According to the above-described feature configuration, it is possible to realize an SOFC monogeneration system that supplies the power load with the power generated by the solid oxide fuel cell using the solid oxide fuel cell with high power generation performance.

  A feature of the SOFC cogeneration system according to the present invention is that the solid oxide fuel cell is provided, and the power and heat generated by the solid oxide fuel cell are supplied to the power load and the heat load.

  According to the above-described feature configuration, it is possible to realize an SOFC cogeneration system that supplies the power load and the heat load with the power and heat generated by the solid oxide fuel cell using the solid oxide fuel cell with high power generation performance. .

FIG. 1 is a schematic view of a solid oxide fuel cell. It is explanatory drawing of the reaction at the time of the action | operation of a solid oxide fuel cell. It is sectional drawing which shows the structure of an inter-cell connection member. BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows the structure of a system provided with the solid oxide fuel cell which mounts the cell for solid oxide fuel cells. It is the schematic of an electricity supply test jig. It is a graph of the electricity supply test result which shows a time-dependent change of electrical resistance. It is a SEM image of the cross section of the cell for solid oxide fuel cells. It is a SEM image of the cross section of the cell for solid oxide fuel cells. It is a SEM image of the cross section of the cell for solid oxide fuel cells.

Hereinafter, a cell for a solid oxide fuel cell (SOFC) according to an embodiment of the present invention will be described with reference to the drawings, and an inter-cell connecting member used therefor.
FIG. 1 is a schematic view of a solid oxide fuel cell. FIG. 2 is an explanatory view of a reaction during operation of the solid oxide fuel cell. As shown in FIG. 1 and FIG. 2, the cell C for SOFC is an air comprising an oxygen ion and an electron conducting porous body on one side of an electrolyte membrane 30 comprising an oxygen ion conducting solid oxide dense body. A single cell 3 is formed by joining the electrode 31 and joining the fuel electrode 32 made of an electron conductive porous body to the other surface side of the electrolyte membrane 30.
Furthermore, the SOFC cell C has a pair of electron conductivity in which the single cell 3 is used to exchange electrons with the air electrode 31 or the fuel electrode 32 and to form a groove 2 for supplying air and hydrogen. It has a structure in which the gas seal body is appropriately held in the outer peripheral edge portion by the intercell connecting member 1 made of an alloy or an oxide. By closely arranging the air electrode 31 and the inter-cell connecting member 1, the groove 2 on the air electrode 31 side functions as an air flow path 2 a for supplying air to the air electrode 31. By closely arranging the fuel electrode 32 and the inter-cell connecting member 1, the groove 2 on the fuel electrode 32 side functions as a fuel flow passage 2 b for supplying hydrogen to the fuel electrode 32. The inter-cell connection member 1 may have a configuration in which a member for electrically connecting the interconnector and the cell C is connected.

For example, the material of the air electrode 31 in LaMO ₃ (for example, M = Mn, Fe, Co, Ni) is described as a general material used in each element constituting the unit cell 3. A perovskite-type oxide of (La, AE) MO _{3 in which a part} of La is substituted by an alkaline earth metal AE (AE = Sr, Ca) can be used. As a material of the fuel electrode 32, a cermet of Ni and yttria stabilized zirconia (YSZ) can be used, and further, as a material of the electrolyte film 30, yttria stabilized zirconia (YSZ) can be used.

  Then, in a state where the plurality of SOFC cells C are stacked and arranged, a pressing force is applied in the stacking direction by the plurality of bolts and nuts, and the cells are held to form a cell stack. In this cell stack, the inter-cell connecting members 1 disposed at both ends in the stacking direction may be any as long as only one of the fuel flow path 2b or the air flow path 2a is formed, and they are disposed in the middle The inter-cell connection member 1 can utilize the one in which the fuel flow path 2b is formed on one side and the air flow path 2a is formed on the other side. In the cell stack having such a laminated structure, the inter-cell connection member 1 may be called a separator.

  The cell stack is attached to a manifold for supplying fuel gas (hydrogen) by an adhesive such as a glass sealing material. For example, crystallized glass is used as the glass sealing material. The glass sealing material is used in places where sealing (sealing) is required such as between the unit cell 3 and the inter-cell connecting member 1 in addition to adhesion of the manifold. An SOFC having such a cell stack structure is generally referred to as a flat SOFC. In the present embodiment, a flat SOFC is described as an example, but the present invention is also applicable to SOFCs having other structures.

At the time of operation of the SOFC provided with such an SOFC cell C, as shown in FIG. 2, air is supplied via the air flow path 2a formed in the inter-cell connection member 1 adjacent to the air electrode 31. At the same time, hydrogen is supplied via the fuel flow path 2b formed in the adjacent inter-cell connecting member 1 to the fuel electrode 32, and the fuel cell is operated at an operating temperature of, for example, about 800.degree. Then, oxygen molecules _{O 2} in the air electrode 31 is an electron e ^- is reacted with oxygen ions ^{O 2-} is generated, the ^{O 2-} passes through the electrolyte membrane 30 to move to the fuel electrode 32, provided at the fuel electrode 32 been H ₂ reacts with the O ^2-H _{2 O} and e ^- and that is generated, the electromotive force E is generated between the pair of cell connecting member 1, outside the electromotive force E It can be taken out and used.

[Inter-cell connecting member]
FIG. 3 is a cross-sectional view showing the structure of the inter-cell connecting member. The inter-cell connection member 1 is configured to include a metal base 11, an oxide film 13 formed on the surface of the metal base 11, and a protective film 12 formed on the oxide film 13. . Then, the inter-cell connection member 1 is joined to the unit cell 3 with the adhesive layer 4 interposed therebetween. Thus, Cr poisoning can be suppressed by providing the protective film 12 so as to cover the surface of the metal base 11, and it is suitable as the cell C for a solid oxide fuel cell.

  The material of the metal base 11 is a material excellent in electron conductivity and heat resistance, and is made of an alloy member (stainless steel) which contains Fe and Cr as main components and contains Ti, Si and Al.

[Oxide film]
An oxide film 13 is formed on the surface of the metal substrate 11. The oxide film 13 is generated by oxidation of the surface of the alloy member of the metal substrate 11 by oxygen in the ambient atmosphere. In the case of a stainless alloy containing Cr as in the present embodiment, the oxide film 13 is formed as a dense film containing chromia (Cr ₂ O ₃ ) as a main component and containing TiO ₂ . The oxide film 13 is formed along with heat treatment in a sintering process of the protective film 12 described later, baking (bonding process) of the adhesive layer 4 and the like.

〔Protective film〕
A protective film 12 is formed on the metal substrate 11. The protective film 12 is a conductive coating film made of a conductive ceramic material containing at least two or more of Zn, Co, and Mn. For example, the conductive coating film is a metal oxide containing Zn, Mn, and Co, for example, Zn _x (Co _y Mn _1-y ) _(3-x) O ₄ (0 <x _{) of} zinc cobalt manganese oxide. A metal oxide containing <1, 0 <y × (3-x) ≦ 2) is a main material. Alternatively, the conductive coating film may be mainly made of ZnCoMnO ₄ . Besides, the conductive coating film is a cobalt manganese metal oxide containing Mn and Co: Mn _x Co _y O ₄ (0 <x, y <3, x + y = 3), for example, MnCo ₂ O ₄ or the like may be used as the main material. In addition, "main material" means that it is a main material, and it is also possible to mix and use a plurality of types of metal oxides or to mix and use other components. By using the protective film 12 which is such a conductive coating film, the mismatch between the thermal expansion coefficient of the protective film 12 and the thermal expansion coefficient of the metal base 11 and the air electrode 31 can be reduced, and the durability of the cell C for SOFC Can be enhanced.

  As a method of forming the protective film 12, wet film forming methods such as screen printing method, doctor blade method, spray coating method, inkjet method, spin coating method, dip coating, electroplating method, electroless plating method, electrodeposition coating method, etc. It can be illustrated.

For example, if the electrodeposition coating method is applied, the protective film 12 can be formed by the following method.
The metal oxide fine particles are dispersed to 100 g per liter of the electrodeposition solution, and electrodeposition coating is performed using a mixed solution containing an anionic resin such as polyacrylic acid. Here, (metal oxide fine particles: anion type resin) = (1: 1) (mass ratio). The electrodeposition coating is carried out, for example, by completely or partially immersing the metal substrate 11 in a current-carrying tank filled with the mixture liquid, and conducting the current with the metal substrate 11 as a plus and the electrode plate of SUS304 as a counter electrode of minus polarity. Thus, an uncured electrodeposited film is formed on the surface of the metal substrate 11. The electrodeposition coating conditions are also not particularly limited, and are wide depending on various conditions such as the type of metal that is the metal substrate 11, the type of mixed solution, the size and shape of the current tank, and the application of the intercell connecting member 1 obtained. The temperature can be appropriately selected from the range, but usually, the bath temperature (mixed liquid temperature) is about 10 to 40 ° C., the applied voltage is about 10 V to 450 V, the voltage application time is about 1 to 10 minutes, the liquid temperature of the mixed liquid is 10 ° C. to 40 ° C. And it is sufficient. The film thickness of the electrodeposition coating can be controlled by changing the electrodeposition voltage and the electrodeposition time. In addition, various pretreatments can be performed on the metal substrate 11.

  The electrodeposition coating cured on the metal substrate 11 by subjecting the metal substrate 11 on which the uncured electrodeposition coating film (protective film material layer described later) is formed to a heat treatment (sintering step described later) A film (protective film 12) is formed. The heat treatment includes pre-drying to dry the electrodeposition coating and curing heating to cure the electrodeposition coating, and curing heating is performed after the pre-drying. After that, heat treatment (for example, baking for 2 hours) in an air atmosphere at a temperature higher than, for example, 1000 ° C. using an electric furnace, and then gradually cooled.

[Adhesive layer]
The inter-cell connection member 1 and the air electrode 31 of the single cell 3 are joined by the adhesive layer 4. Specifically, the protective film 12 formed on the surface of the metal base 11 of the inter-cell connecting member 1 and the air electrode 31 of the unit cell 3 are adhered and bonded by the adhesive layer 4. As a main material of the bonding layer 4, a perovskite type oxide similar to the air electrode 31 or a spinel type oxide is used. For example _{LSCF6428 (La 0.6 Sr 0.4 Co 0.2} Fe 0.8 O 3- δ) is used.

[Method of Manufacturing Cell for Solid Oxide Fuel Cell]
Next, a method of manufacturing the solid oxide fuel cell C will be described. The method of manufacturing the cell C for solid oxide fuel cell comprises the steps of manufacturing the inter-cell connecting member 1 (the following “protective film forming step”), and the inter-cell connecting member 1 with the air electrode 31 and the fuel electrode 32. And a bonding process (hereinafter referred to as "bonding process").

[Protective film formation process]
The protective film formation process which is a manufacturing method of the cell connection member 1 of this invention has a film forming process and a sintering process. In the protective film forming step, the protective film 12 is formed on the surface of the metal base 11 of the inter-cell connecting member 1.

  In the film forming step, a protective film material layer containing at least two or more of Zn, Co, and Mn is wet-formed on the surface of the metal substrate 11. For example, using a slurry containing a fine powder of a metal oxide containing at least two or more of Zn, Co, and Mn, the coating film (protective film material layer) is wetted on the metal base 11 of the intercell connection member 1 Produce a film. The wet film formation may be performed by the above-described electrodeposition coating method, or may be performed by dipping the metal substrate 11 in the slurry and pulling it up (dip), or any of the other methods exemplified above. You may use. The wet film formation may be performed on the whole of the metal base 11 or may be performed only on one side of the flat metal base 11. In the latter case, the surface on which the wet film formation is performed and the protective film 12 is formed is bonded to the air electrode 31 of the unit cell 3. The wet film formation is not performed, and the surface of the metal base 11 exposed is bonded to the fuel electrode 32 of the unit cell 3.

  In the sintering step, the metal base 11 on which the coating film (protective film material layer) is formed by the film forming step is subjected to heat treatment at a temperature higher than 1000.degree. The film material layer is sintered to form a protective film 12 which is a conductive coating film made of a conductive ceramic material on the surface of the metal substrate 11. The heat treatment is performed under an air atmosphere, for example, at a temperature higher than 1000 ° C. for 2 hours. As described above, the heat treatment in the sintering step of the protective film formation step is performed in a state where the unit cell 3 of the SOFC cell C and the metal base 11 are not joined. That is, after the protective film 12 is formed by performing this sintering process, a bonding process described later is performed.

Bonding process
In the bonding step, the inter-cell connecting member 1 obtained in the protective film forming step (the film forming step and the sintering step) is bonded to the air electrode 31 of the unit cell 3 through the adhesive layer 4. Similarly, the fuel electrode 32 of the unit cell 3 and the inter-cell connecting member 1 are joined via the adhesive layer 4. Specifically, a paste containing the material of the adhesive layer 4 described above is applied to the inter-cell connecting member 1 and bonded to the unit cell 3, and heat treatment is performed to form the adhesive layer 4 by baking. The heat treatment is usually performed at a low temperature of the fuel cell operating temperature to 950 ° C., but is not limited to this temperature.
As described above, the SOFC cell C formed by joining the inter-cell connection member 1 and the air electrode 31 is manufactured.

  FIG. 4 is a view showing the configuration of a system including a solid oxide fuel cell mounted with the solid oxide fuel cell C produced by the above-described method. In particular, FIG. 4 shows a SOFC cogeneration system including a solid oxide fuel cell (SOFC) 20 and supplying power and heat generated by the solid oxide fuel cell 20 to a power load and a heat load. It is a figure showing composition. The solid oxide fuel cell 20 has a cell stack in which a plurality of solid oxide fuel cell cells C manufactured as described above are stacked. Further, although not shown, in the solid oxide fuel cell 20, a reformer for producing a fuel gas such as hydrogen supplied to the fuel electrode 32 by reforming a hydrocarbon such as a city gas You may use

  The power output from the solid oxide fuel cell 20 is supplied to the power line 22 connected to the commercial power system 21 through the power converter 24 such as an inverter. Connected to the power line 22 are various power load devices 23 such as lighting devices and air conditioners used in a facility where the solid oxide fuel cell 20 is installed. That is, power is supplied from at least one of the commercial power grid 21 and the solid oxide fuel cell 20 to the power load in the power load device 23.

  The heat discharged from the solid oxide fuel cell 20 is applied to the heat load of various heat load devices 26 such as a water heater and a heating device installed in a facility where the solid oxide fuel cell 20 is installed. Is supplied. Further, as shown in the figure, if the heat storage device 25 for storing the heat storage medium is provided, the heat discharged from the solid oxide fuel cell 20 can be recovered by the heat storage medium and stored by the heat storage device 25. Then, when heat demand is generated in the heat load device 26, heat can be supplied from the heat storage device 25 to the heat load device 26.

[Change in electrical resistance of inter-cell connection member due to difference in Ti content in metal substrate 11]
In the present embodiment, the effect of employing a material having a high Ti content rate as the metal base 11 used in manufacturing the inter-cell connecting member 1 was verified. In particular, it was verified that the electronic conductivity in the highly resistant oxide film 13 could be improved by diffusing Ti into Cr ₂ O ₃ . Specifically, experimental samples are prepared according to the method of manufacturing the solid oxide fuel cell C described above, and measurement of the change in electric resistance over time and SEM observation of the cross section of the inter-cell connecting member 1 are performed. The effect was verified.

[Preparation of experimental sample]
[Sample 1: Example]
Anion electrodeposition coating method using a slurry containing fine powder of MnCo ₂ O _{4 on} the surface of a plate of an alloy material containing Fe and Cr as main components and containing Ti, Si and Al used as the metal substrate 11 The coating film (protective film material layer) was formed into a film by this (film forming process). The content rate of Cr in the alloy material used for this sample 1 was 22.2 (mass%), and the content rate of Ti was 0.200 (mass%).
The plate was heated at a temperature of 1050 ° C. for 2 hours in a sintering process to form a protective film 12 mainly composed of MnCo ₂ O ₄ . LSCF 6428 was applied on both sides of the plate, dried, and baked at 1000 ° C. for 2 hours to form a layer simulating the adhesive layer 4. As described above, a sample 1 imitating the inter-cell connecting member 1 of the solid oxide fuel cell was prepared. The content of Ti in the oxide film (Cr ₂ O ₃ ) 13 formed after the sintering step was 0.98 (mass%).

[Sample 2: Example]
The content of Cr in the alloy material of the metal base 11 used for the sample 2 as an example is 22.2 (% by mass), and the content of Ti is 0.234 (% by mass). The other conditions were the same as those of sample 1 to prepare sample 2. The content of Ti in the oxide film (Cr ₂ O ₃ ) 13 formed after the sintering step was 1.13 (mass%).

[Sample 3: Comparative Example]
The content of Cr in the alloy material of the metal base 11 used for the sample 3 as a comparative example was 22.2 (% by mass), and the content of Ti was 0.146 (% by mass). The other conditions were the same as in Sample 1 to prepare Sample 3. The content of Ti in the oxide film (Cr ₂ O ₃ ) 13 formed after the sintering step was 0.56 (mass%).

Table 1 summarizes the content of Cr and the content of Ti in the alloy material of the metal base 11 used in Samples 1 to 3 (before the production of the inter-cell connection member 1), and Table 2 shows The contents of Ti in the oxide film 13 formed after performing the sintering process on the samples 1 to 3 are summarized. Although Table 2 shows the content of Ti in the oxide film 13, it is considered that Ti is present in the oxide film 13 in the state of oxide (TiO ₂ ).
As can be seen from Tables 1 and 2, the Ti content in the alloy material of the metal substrate 11 is increased, and the Ti content in the oxide film 13, that is, the TiO ₂ content is increased. It can confirm.

[Temporal change of electric resistance]
About the samples 1-3, the time-dependent change of the electrical resistance value was measured. The results of the energization test are shown in the graph of FIG. The measurement was carried out by setting each sample in the energization test jig 5 shown in FIG. 5 and measuring the electric resistance over time in a constant current state under an environment of 800 ° C. The conduction test jig 5 has a structure in which a sample is sandwiched between a pair of metal plates 51 and fixed by screws 52. The Pt mesh 53 was in contact with the adhesive layer 4, and the resistance between the pair of Pt meshes 53 was measured to measure the resistance of the sample.

FIG. 6 is a graph of the results of the electrification test at 800 ° C. In FIG. 6, the horizontal axis is the elapsed time, and the vertical axis is the electrical resistance.
For example, when based on sample 1 (example), it turned out that initial resistance increases in sample 3 (comparative example) in which the content of Ti in the alloy material of the metal base 11 is small. On the other hand, in the sample 2 (Example) in which the content of Ti in the metal substrate 11 was increased, a decrease in initial resistance and a decrease in resistance over time were also confirmed. This is considered to be because the electron conductivity is improved and the performance is improved by the diffusion of Ti into the oxide film (Cr ₂ O ₃ ) 13 by the heat treatment performed at the time of sample preparation. In addition, it is considered that there is also an effect by the diffusion of Ti gradually into the oxide film (Cr ₂ O ₃ ) 13 under the environment of 800 ° C. during the current test.

  FIGS. 7-9 is a SEM image of the cross section of the cell for solid oxide fuel cells after the said conduction test with respect to the samples 1-3. The metal substrate 11, the oxide film 13 and the protective film 12 are arranged in order from the top of the image. In the samples 1 to 3, it can be confirmed that the growth degree of the oxide film 13, that is, the thickness, is substantially the same. Moreover, since the coating composition, the baking condition, and the thickness of the protective film 12 are almost the same in Samples 1 to 3, the resistance difference in the present example and the comparative example is due to the resistance difference in the oxide film 13 it is conceivable that. From the above, by using a stainless steel material having a high Ti content as the alloy material of the metal substrate 11, Ti is preferentially diffused in the oxide coating layer having high insulating property, and the initial resistance reduction effect and temporally It is considered that the effect of reducing various resistances can be obtained.

As described above, when the oxide coating 13 mainly composed of Cr ₂ O ₃ contains TiO ₂ , the electric resistance of the inter-cell connecting member is reduced, and the cell for solid oxide fuel cell with high power generation performance Can be realized.
Moreover, when the content rate of Ti in the oxide film 13 is 0.9 mass% or more, it is preferable at the point to which the reduction effect of the electrical resistance of the cell connection member 1 becomes large. Here, it is preferable in the point which the reduction effect of the electrical resistance of the cell connection member 1 becomes large as the content rate of Ti in the oxide film 13 is 1.1 mass% or more.
Furthermore, when the content of Ti in the alloy member constituting the metal substrate 11 is 0.20 mass% or more, the content of Ti contained in the oxide film 13 formed on the surface is increased, It is preferable in that the electrical resistance of the oxide film 13 can be reduced. Here, when the content of Ti in the alloy member constituting the metal substrate 11 is 0.23 mass% or more, the content of Ti contained in the oxide film 13 formed on the surface is further increased. Is preferable in that

Another Embodiment
<1>
In the above embodiment, the inter-cell connecting member, the solid oxide fuel cell, the solid oxide fuel cell, the SOFC monogeneration system, and the SOFC cogeneration system of the present invention have been described by way of specific examples. Can be changed as appropriate.

<2>
Although the example which built the cogeneration system provided with solid oxide fuel cell (SOFC) 20 was demonstrated in the said embodiment, the monogeneration system provided with SOFC 20 can also be built. That is, it is also possible to construct an SOFC monogeneration system that includes the solid oxide fuel cell 20 and supplies the power generated by the solid oxide fuel cell 20 to the power load.

<3>
The configurations disclosed in the above embodiments (including the other embodiments, the same shall apply hereinafter) can be applied in combination with the configurations disclosed in the other embodiments as long as no contradiction arises, and are disclosed in the present specification. The embodiment is an exemplification, and the embodiment of the present invention is not limited thereto, and can be appropriately modified within the scope of the object of the present invention.

  The present invention relates to an inter-cell connection member for a solid oxide fuel cell having high power generation performance, a cell for a solid oxide fuel cell, a solid oxide fuel cell, and an SOFC monogeneration system, , SOFC cogeneration system can be used.

Reference Signs List 1 inter-cell connection member 11 metal base 12 protective film 13 oxide film 20 solid oxide fuel cell (SOFC)
23 Power Load Device 26 Heat Load Device 31 Anode C Solid Oxide Fuel Cell Cell (SOFC Cell)

Claims (11)

A metal base composed of an alloy member containing Fe and Cr as main components and containing Ti, Si and Al;
An oxide film containing Cr ₂ O ₃ as a main component and containing TiO ₂ formed on the surface of the metal substrate;
And a conductive coating film formed of a conductive ceramic material containing at least two or more of Zn, Co, and Mn formed on the oxide film.   The inter-cell connecting member according to claim 1, wherein the content of Ti in the oxide film is 0.9% by mass or more.   The inter-cell connecting member according to claim 1 or 2, wherein the content of Ti in the alloy member is 0.20 mass% or more.   The inter-cell connection member according to any one of claims 1 to 3, wherein the conductive coating film mainly contains a metal oxide containing Zn, Mn and Co. The conductive coating film is mainly composed of a metal oxide containing Zn _x (Co _y Mn _1-y ) _(3-x) O ₄ (0 <x <1, 0 <y × (3-x) ≦ 2) The inter-cell connection member according to any one of claims 1 to 3, wherein Intercell connecting member according to claim 1, wherein the conductive coating film is a ZnCoMnO ₄ as a main material.   The inter-cell connection member according to any one of claims 1 to 6, wherein the conductive coating film is formed by electrodeposition coating.   The cell for solid oxide fuel cells by joining the cell connection member as described in any one of Claims 1-7, and an air electrode.   A solid oxide fuel cell equipped with the solid oxide fuel cell according to claim 8.   An SOFC monogeneration system comprising the solid oxide fuel cell according to claim 9, and supplying power generated by the solid oxide fuel cell to an electric load.   An SOFC cogeneration system comprising the solid oxide fuel cell according to claim 9, and supplying power and heat generated by the solid oxide fuel cell to the power load and the heat load.