JP2017168358A - Intercellular connection member and cell for solid oxide fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cell for a solid oxide fuel cell (SOFC) which suppresses growth of an oxide film on an alloy surface which causes an increase in electrical resistance, and has high power generation performance.SOLUTION: In an intercellular connection member 1 having a base material 11 and a protective film 12 formed on the surface of the base material 11, the base material 11 contains Cr, an alloy whose content of Si is less than 0.39 mass%, preferably, 015 to 30 mass% is a main material, and a protective film 12 has a spinel type metal oxide as a main material. The protective film is mainly composed of a metal oxide containing Zn, Mn, and Co.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an inter-cell connecting member and a solid oxide fuel cell.

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

An alloy used in such a SOFC cell is manufactured from a material containing Cr having excellent electron conductivity and heat resistance. Further, the heat resistance of such an alloy is derived from a dense film of chromia (Cr ₂ O ₃ ) formed on the surface of the alloy.

  In addition, in the manufacturing process of the SOFC cell, for the purpose of minimizing the contact resistance between the alloy, etc., the air electrode and the fuel electrode as much as possible, in a state where they are laminated, the operating temperature is higher than 1000 ° C. There is a case where a baking treatment is performed at a baking temperature of about 1250 ° C. (see, for example, Patent Document 1).

  On the other hand, an n-type semiconductor film formed by doping impurities into a single oxide is formed on the surface of the alloy used in the SOFC cell, and is included in the alloy by performing such a film forming process. There has also been a technique for suppressing the oxidation of Cr into a hexavalent oxide that easily scatters (see, for example, Patent Document 2).

As described above, in an SOFC cell formed by joining an alloy containing Cr and the air electrode, when the alloy is exposed to a high temperature during operation or the like, Cr contained in the alloy or the like is moved to the air electrode side. There is a problem that air poisoning causes Cr poisoning.
Such Cr poisoning of the air electrode inhibits the oxygen reduction reaction for the generation of oxide ions in the air electrode, increases the electrical resistance of the air electrode, and further decreases the Cr concentration of alloys and the like. This may cause problems such as a decrease in the heat resistance of the alloy itself, resulting in a decrease in SOFC performance.

  In addition, as in Patent Document 1, when performing a firing process in which an alloy or the like and an air electrode are joined, the oxide of Cr (VI) is exposed to a firing temperature higher than the operating temperature. Is generated and reacts with the air electrode to generate a Cr compound, and Cr poisoning of the air electrode occurs.

JP 2004-259634 A International Publication No. 2007/083627

  In order to avoid the above-described problem of Cr poisoning in the air electrode, it is considered to cover the surface of an alloy or the like with a protective film made of a metal oxide. In this case, the SOFC cell is exposed to an oxidizing atmosphere (air atmosphere) at a higher temperature (1000 ° C. or higher) than the operating temperature (for example, 650 ° C. to 900 ° C.) at the stage of manufacturing the SOFC cell. Then, even when a protective film is provided on the surface, oxidation of the alloy surface occurs to some extent, that is, an oxide film is formed, and the electrical resistance increases. When this electrical resistance is large, the power generation performance of the fuel cell is low.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a SOFC cell having high power generation performance by suppressing the growth of an oxide film on the surface of an alloy that causes an increase in electrical resistance. is there.

  The characteristic configuration of the inter-cell connecting member according to the present invention for achieving the above object is an inter-cell connecting member having a base material and a protective film formed on the surface of the base material, An alloy containing Cr and a Si content of less than 0.39% by mass is the main material, and the protective film is a spinel metal oxide as the main material.

As a result of intensive studies, the inventors have found that the amount of Si contained in the base material of the inter-cell connection member greatly affects the electrical resistance of the inter-cell connection member in the state where the protective film is formed. Experiments confirmed that the electrical resistance can be greatly reduced by using an alloy having a Si content of less than 0.39% by mass as a main material. This is considered to be because the growth of the oxide film (SiO ₂ ) derived from Si was suppressed.

  That is, according to the above characteristic configuration, in the inter-cell connecting member having the base material and the protective film formed on the surface of the base material, the base material contains Cr and the Si content rate is 0.39 mass. % Of the alloy is the main material, and the protective film is the spinel metal oxide as the main material, so that the electrical resistance of the inter-cell connection member is greatly reduced to realize a SOFC cell with high power generation performance. Is possible.

When the Si content of the alloy is 0.30% by mass or less, the electrical resistance of the inter-cell connecting member can be further reduced, which is preferable.

  Another characteristic configuration of the inter-cell connecting member according to the present invention is that the Si content of the alloy is greater than 0.15% by mass.

  To reduce the Si content of the alloy, a high cost is required in the alloy manufacturing process. By making the Si content of the alloy greater than 0.15 mass%, it is possible to reduce the electrical resistance while suppressing an increase in cost. That is, according to said characteristic structure, the connection member between cells which can make cost and performance compatible can be provided.

  Another characteristic configuration of the inter-cell connecting member according to the present invention is that the protective film is mainly composed of a metal oxide containing Zn, Mn, and Co.

According to the above characteristic configuration, the protective film is mainly composed of a metal oxide containing Zn, Mn, and Co, so that the thermal expansion coefficient of the protective film and the thermal expansion coefficient of the base material and the air electrode are inconsistent. It can be made small, and the durability of the SOFC cell can be increased, which is preferable. More preferably, the protective film is mainly composed of Zn _x (Co _y Mn _(1-y) ) _(3-x) O ₄ (0 <x <1, 0 <y × (3-x) ≦ 2). . Further, when the protective film is mainly made of ZnCoMnO ₄ , the resistance value can be reduced according to the Si content rate in the inter-cell connecting member configured in combination with the base material having the Si content rate of less than 0.39% by mass. It has been confirmed by experiments.

  Another characteristic configuration of the inter-cell connecting member according to the present invention is that the protective film is formed by electrodeposition coating.

  According to the above characteristic configuration, a dense and strong protective film can be realized, which is preferable.

  In order to achieve the above object, the characteristic configuration of the solid oxide fuel cell according to the present invention resides in that the inter-cell connecting member and the air electrode are joined.

  According to the above characteristic configuration, since the cell for a solid oxide fuel cell is configured by joining the inter-cell connecting member and the air electrode, the electric resistance of the inter-cell connecting member is greatly reduced to generate power. A high-performance SOFC cell can be realized.

Schematic diagram of solid oxide fuel cell Explanatory diagram of reaction during operation of solid oxide fuel cell Cross-sectional view of inter-cell connecting member joint structure Graph showing voltage drop temperature change

  Hereinafter, the inter-cell connection member and the solid oxide fuel cell according to the present embodiment will be described. In the following, preferred examples will be described, but these examples are described in order to more specifically illustrate the present invention, and various modifications can be made without departing from the spirit of the present invention. The present invention is not limited to the following description.

<Solid oxide fuel cell>
An embodiment of an inter-cell connecting member for SOFC and a manufacturing method thereof according to the present invention will be described with reference to the drawings.
The SOFC cell C shown in FIGS. 1 and 2 has an air electrode made of an oxide ion and an electron conductive porous body on one side of an electrolyte membrane 30 made of a dense oxide oxide conductive solid oxide. 31 and a single cell 3 formed by joining a fuel electrode 32 made of an electron conductive porous body to the other surface side of the electrolyte membrane 30.

  Further, the SOFC cell C exchanges electrons with the single cell 3 with respect to the air electrode 31 or the fuel electrode 32, and at the same time, a pair of electron conductive materials having grooves 2 for supplying air and hydrogen. It has a structure in which a gas seal body is appropriately sandwiched between outer peripheral edges by an inter-cell connecting member 1 in which a protective film 12 is formed on a base material 11 made of an alloy or oxide. And the said groove | channel 2 by the side of the air electrode 31 functions as the air flow path 2a for supplying air to the air electrode 31, because the air electrode 31 and the inter-cell connection member 1 are closely arranged, The groove 2 on the fuel electrode 32 side functions as a fuel flow path 2 b for supplying hydrogen to the fuel electrode 32 by arranging the fuel electrode 32 and the inter-cell connecting member 1 in close contact with each other.

In addition, when a general material used in each element constituting the SOFC cell C is described, for example, the material of the air electrode 31 is LaMO ₃ (for example, M = Mn, Fe, Co). A perovskite oxide of (La, AE) MO ₃ in which a part of La of Al is substituted with an alkaline earth metal AE (AE = Sr, Ca) can be used. And yttria-stabilized zirconia (YSZ) can be used, and yttria-stabilized zirconia (YSZ) can be used as the material of the electrolyte membrane 30.

  As the material of the inter-cell connection member 1, Fe-Cr alloy that is ferritic stainless steel, Fe-Cr-Ni alloy that is austenitic stainless steel, Ni-Cr alloy that is nickel-based alloy, and the like, An alloy containing Cr is used. Especially in this embodiment, the connection member between cells which uses as a main material the alloy whose Si content rate is less than 0.39 mass% is used.

In a state where a plurality of SOFC cells C are arranged in a stacked manner, a pressing force is applied in the stacking direction by a plurality of bolts and nuts 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 one in which only one of the fuel flow path 2b or the air flow path 2a is formed, and is disposed in the other middle. As the inter-cell connecting member 1, a member in which the fuel channel 2b is formed on one surface and the air channel 2a is formed on the other surface can be used. In the cell stack having such a laminated structure, the inter-cell connecting member 1 may be referred to as a separator.
An SOFC having such a cell stack structure is generally called a flat-plate SOFC. In the present embodiment, a flat SOFC will be described as an example. However, the present invention is applicable to SOFCs having other structures.

When the SOFC having such a SOFC cell C is operated, air is passed through the air flow path 2a formed in the inter-cell connecting member 1 adjacent to the air electrode 31, as shown in FIG. While supplying, hydrogen is supplied through the fuel flow path 2b formed in the inter-cell connecting member 1 adjacent to the fuel electrode 32, and operates at an operating temperature of about 800 ° C., for example. Then, the air electrode 31 O ₂ electrons e ^- are reacting with O ^2- is generated, the O ^2- passes through the electrolyte membrane 30 to move to the fuel electrode 32, H ₂ supplied in the fuel electrode 32 Reacts with the O ²⁻ to generate H ₂ O and e ⁻ , so that an electromotive force E is generated between the pair of inter-cell connecting members 1, and the electromotive force E is taken out and used. be able to.

<Cell connecting member>
As shown in FIGS. 1 and 3, the inter-cell connection member 1 is configured, for example, by providing a protective film 12 on the surface of a base material 11 made of a ferritic stainless alloy. And it forms in the shape of a groove plate which makes it possible to connect between single cells, forming the air flow path 2a and the fuel flow path 2b between each single cell 3. FIG.

  The protective film 12 is formed as a thick film by electrodeposition coating a base material 11 with a coating film-forming material containing a conductive ceramic material.

<Protective film>
The protective film 12 has, on the surface of the base material 11, a metal oxide fine particle such as ZnCoMnO ₄ and an anionic resin such as polyacrylic acid in a mass ratio (metal oxide fine particle: anionic resin) = (0. 5: 1) to (1.7: 1) is used to perform an electrodeposition step of forming an electrodeposition coating film by an anionic electrodeposition coating method using a mixed solution containing the ratio of the electrodeposition coating film. Performing a firing step of firing to form a fired coating in which the resin component in the electrodeposition coating is burned off, and further sintering the fired coating to form a protective film 12 made of a metal oxide It is formed by doing. In addition, the said liquid mixture is an electrodeposition coating material used in order to form an electrodeposition coating film by the anion electrodeposition coating method. In the following description, the description of “mixed liquid” is unified, but for forming the protective film 12, the above-described mixed liquid, that is, an electrodeposition paint composed of the mixed liquid is used.

When the thermal expansion coefficient is verified here, ZnCoMnO ₄ is 11 × 10 ⁻⁶ K ^−1, which is mainly used as a base material compared to 9.3 × 10 ⁻⁶ K ⁻¹ of ZnCo ₂ O _4. Ferritic stainless steel (thermal expansion coefficient: 11 × 10 ⁻⁶ K ⁻¹ ) and (La, Sr) (Co, Fe) O ₃ (thermal expansion coefficient: 15) which is an air electrode material used by joining. ˜21 × 10 ⁻⁶ K ⁻¹ ) and (La, Sr) MnO ₃ (thermal expansion coefficient: 11 × 10 ⁻⁶ K ⁻¹ ).

  Although the specific manufacturing method of the said protective film 12 is explained in full detail below, this invention is not limited to a following example.

(1) Synthesis of anionic resin 50 parts of 1,4 dioxane was heated to about 82 ° C. in a four-necked flask equipped with a reflux condenser, a thermometer, a stirrer, and a dropping funnel, and the dropping funnel was stirred. To the mixture shown in Table 1 below and 50 parts of 1,4 dioxane are continuously added dropwise over 3 hours.
After completion of the dropwise addition, the reaction is continued for 3 hours at the same temperature to synthesize an anionic acrylic resin (solid content 50 mass%). The obtained anion type resin had a Tg of −27 ° C. (calculated estimate) and a molecular weight MW of 120,000 to 150,000.

表１中のＡＩＢＮは、重合開始剤である。Ｌ−ＳＨは、連鎖移動剤である。

AIBN in Table 1 is a polymerization initiator. L-SH is a chain transfer agent.

The chemical properties of the anionic resin are preferably Tg: −50 ° C. to + 25 ° C. and molecular weight (MW mass average molecular weight): 50,000 to 200,000. In general, the Tg of an anionic resin is around + 20 ° C., and the MW is about 30,000 to 70,000. In order to improve the eutectoid rate by electrophoretically coagulating a large amount of inorganic fine particles and generating an electrolytic gas locally, it is preferable to use an anionic resin having a low Tg and a high molecular weight. If Tg is -50 ° C. or less, precipitation coating viscosity greater fluidity after bake hardening too strong, + 25 and liquidity ° C. becomes higher can not be erased gas traces generated in reduced ZnCoMnO ₄ particles both analysis time It becomes a pinhole shape. When the MW is 50,000 or less, the dispersibility of the ZnCoMnO ₄ fine particles decreases. On the other hand, when it is 200,000 or more, the fluidity is lowered, the uniform dispersion of the ZnCoMnO ₄ fine particles in the coating film is deteriorated, and the appearance is not uniform.

In addition, when an anionic resin and metal oxide fine particles are subjected to a coupling reaction using a silane coupling agent described later, the deposition efficiency of metal oxide fine particles represented by ZnCoMnO ₄ fine particles can be dramatically improved. it can.

(2) as a mixture of creating a silane coupling agent, with isocyanate-functional silane _{(OCN-C 3 H 6 -Si} (OC 2 H 5) 3), the solvent nMP (n-methyl pyrrolidone) and 3 parts by weight After mixing 120 parts by mass of the anionic resin prepared in (1) and 60 parts of the solvent nMP (n-methylpyrrolidone), a tin-based catalyst (DBTDL 0.2 part) was added and reacted at 60 ° C. for 1 hour, whereby silane The isocyanate group of the coupling agent reacts with the OH group of the anionic resin, and the silane coupling agent is added to the anionic resin. (Table 2 first component)

100 parts by weight of ZnCoMnO ₄ fine particles (average particle size 0.5 μm), 200 parts of solvent nMP (n-methylpyrrolidone) and 750 parts by weight of zirconia beads having a diameter of 3 mm are mixed and wet dispersed with a stirrer to form slurry-like ZnCoMnO _4. Get fine particles. (Table 3 second component)

The first component is added to the second component and mixed uniformly.
Further, 1.4 parts by mass of triethylamine, 10 parts by mass of a solvent nMP (n-methylpyrrolidone) and 10 parts by mass of an antifoaming agent (Surfinol 104) are added and stirred.
After uniform mixing, 500 parts by mass of ion-exchanged water is added little by little to prepare a mixed solution of ZnCoMnO ₄ fine particles and an anionic resin. After stirring for 24 hours to promote hydrolysis reaction of the silane coupling agent, impurities are removed by ion exchange treatment, and a mixed solution having a pH of 9.0 ± 0.2 bath conductivity of 200 ± 50 μS / cm is obtained. The obtained dispersion is used as a mixed liquid of ZnCoMnO ₄ fine particles: resin = 1: 1 (mass ratio).

Note that in ZnCoMnO ₄ microparticles changing the mixing ratio of the first component and the second component blend of the following: resin = 0.5: 1 (weight ratio) 1.7: can create a 1 (mass ratio).

(3) Electrodeposition coating The anionic dispersant composition prepared in (2) above is dispersed so that the dispersant particles in the electrodeposition solution are 100 g per liter of electrodeposition solution, and a direct current voltage is applied in a solution at 25 ° C. Electrodeposition coating was performed at 40 V for 30 seconds under stirring with a stirrer (20 rpm).
Electrodeposition coating was performed as follows.

  By performing degreasing treatment, pickling treatment, etc., if necessary, on the test piece of the base material 11 having a simple shape with a rectangular cross-section, immersing the article to be treated in the mixed solution, and conducting electricity, An uncured electrodeposition coating film is formed on the surface of the substrate 11.

(3-1) Pretreatment In addition, the pretreatment which performs the following 1-7 in order on each electrode was performed.
1. Cathodic electrolysis with electrolytic cleaner (Activator S (manufactured by Shimizu) 100 g / L, 40 ° C., 10 A / dm 2, 30 seconds)
2. 2. Washing with water Anode electrode electrolysis with electrolytic cleaner (Activator S (manufactured by Shimizu) 100 g / L, 40 ° C., 10 A / dm 2, 30 seconds)
4). 5. Washing with water Acid neutralization (Nitric acid 200mL / L)
6). 6. Washing with water Pure water washing

Moreover, you may perform a degreasing process, a pickling process, etc. separately to the test piece of the base material 11 used as an anode.
A degreasing process is performed by supplying alkaline aqueous solution to the surface of the base material 11, for example. The supply of the alkaline aqueous solution is performed, for example, by spraying the alkaline aqueous solution onto the base material 11 or immersing the base material 11 in the alkaline aqueous solution. As the alkali, those commonly used for metal degreasing can be used, and examples include alkali metal phosphates such as sodium phosphate and potassium phosphate. The alkali concentration in the aqueous alkali solution is appropriately determined according to, for example, the type of metal to be treated, the degree of contamination of the substrate 11, and the like. Furthermore, the alkaline aqueous solution may contain an appropriate amount of a surfactant such as an anionic surfactant and a nonionic surfactant. Degreasing is performed at a temperature of about 20 to 50 ° C. (liquid temperature of the alkaline aqueous solution) and is completed in about 1 to 5 minutes.

  After degreasing, the substrate 11 is washed with water and subjected to the next pickling treatment. In addition, degreasing to be immersed in an acidic bath, bubbling immersion degreasing, electrolytic degreasing, and the like can be appropriately combined. The pickling treatment is performed, for example, by supplying an acid aqueous solution to the surface of the substrate 11. The supply of the acid aqueous solution is performed by spraying the acid aqueous solution on the base material 11 or immersing the base material 11 in the acid aqueous solution, as in the case of supplying the alkaline aqueous solution in the degreasing treatment. As the acid, those commonly used for metal pickling can be used, and examples thereof include sulfuric acid, nitric acid, and phosphoric acid. The acid concentration in the acid aqueous solution is appropriately determined according to, for example, the type of the substrate 11. The pickling treatment is performed at a temperature of about 20 to 30 ° C. (liquid temperature of the acid aqueous solution) and is completed in about 15 to 60 seconds. In addition to the degreasing treatment and pickling treatment, scale removal treatment, ground treatment, rust prevention treatment, and the like may be performed. After these treatments, the base material 11 is dried at a temperature of about 70 to 120 ° C. and used for the next electrodeposition coating.

(3-2) Electrodeposition process In this way, in the 25 ° C. solution, the test piece of the base material 11 subjected to the pretreatment was made positive with the base material 11 as a counter electrode and the SUS304 electrode plate with a negative polarity. An uncured electrodeposition coating film is formed on the surface of the substrate 11 by energizing with a stirrer stirring (20 rpm) for 30 seconds at a DC voltage of 40V.
In addition, the film thickness of the electrodeposition coating film can be controlled by changing the electrodeposition voltage and the electrodeposition time.

  The base material 11 after the electrodeposition process is taken out from the energization tank and subjected to heat treatment. By heating the base material 11 on which the uncured electrodeposition coating film is formed, the cell connection member 1 on which the cured electrodeposition coating film is formed on the surface of the base material 11 is obtained.

The electrodeposition coating is carried out according to a known method, for example, by immersing the base material 11 completely or partially in an energization tank filled with the mixed solution as an anode and energizing.
Electrodeposition coating conditions are not particularly limited, and a wide range is available depending on various conditions such as the type of metal that is the substrate 11, the type of the mixed solution, the size and shape of the current-carrying tank, and the use of the resulting cell connection member 1. Usually, the bath temperature (mixed solution temperature) is about 10 to 50 ° C., the applied voltage is about 10 to 450 V, the voltage application time is about 1 to 10 minutes, and the liquid temperature of the mixed solution is 10 to 45 ° C. do it.

  The heat treatment includes preliminary drying for drying the electrodeposition coating film and curing heating for curing the electrodeposition coating film, and curing heating is performed after the preliminary drying. The preliminary drying is performed under heating at about 60 to 140 ° C. and is completed in about 3 to 30 minutes. Curing heating is performed under heating at about 150 to 220 ° C. and is completed in about 10 to 60 minutes. Thus, the electrodeposition coating film by the said liquid mixture is obtained.

(3-3) (Firing process and sintering process)
An electrodeposition coating film formed using ZnCoMnO ₄ fine particles: resin = 1: 1 (mass ratio) as the mixed liquid was held at 500 ° C. for 2 hours and subjected to a baking step in which the acrylic resin was burned off, and then 1000 A sintering process for causing the ZnCoMnO ₄ particles to sinter and react with the surface of the test piece of the base material 11 by raising the temperature to 0 ° C. and holding it for 2 hours; A dense protective film 12 was formed.

<Relationship between Si content and electrical resistance>
The base material 11 was created using five types of ferritic stainless steel alloys (SUS445J1) having different Si contents. Then the ZnCoMnO ₄ on the surface of the substrate 11 by the methods described above to form a protective film 12 to the main material, samples were prepared in the intercell connection member according to Examples 1 to 4 and Comparative Example 1. Table 4 shows the Si content of each sample.

The above sample was placed in six temperature environments of 600 ° C to 850 ° C simulating the operating temperature of a solid oxide fuel cell, and the voltage drop when a DC current of 0.32 A / cm ^-2 was passed was measured. did. The six temperature environments are 600 ° C., 650 ° C., 700 ° C., 750 ° C., 800 ° C., and 850 ° C. The results are shown in FIG.

The graph of FIG. 4 plots the voltage drop of each sample with the horizontal axis representing temperature and the vertical axis representing voltage drop. Since the voltage drop is measured with a constant current, a sample with a large voltage drop has a high resistance value. The voltage drop of the comparative example 1 became large compared with the other Examples 1-4. For example, at 650 ° C., a voltage drop of 50 mV or more is larger than in other Examples 1 to 4. About Examples 1-4, although the big difference did not arise in the value of a voltage drop, the tendency for a voltage drop to become small is seen as Si content rate becomes small. In each sample, the voltage drop decreases (that is, the resistance value increases) as the temperature increases. From this, the voltage drop shown in FIG. 4 is mainly caused by the semiconductor, and is considered to be caused by a metal oxide such as SiO ₂ . From the above results, by using a base material whose main material is an alloy having a Si content of less than 0.39% by mass, the growth of the oxide film on the surface of the alloy causing an increase in electrical resistance is suppressed, Thus, it has been shown that the SOFC cell having high power generation performance can be provided by reducing the electrical resistance of the inter-cell connecting member. The Si content of the alloy is preferably 0.30% by mass or less, more preferably 0.25% by mass or less, and further preferably 0.20% by mass or less.

1: Cell connecting member 2: Groove 2a: Air flow path 2b: Fuel flow path 3: Single cell 11: Base material 12: Protective film 30: Electrolyte film 31: Air electrode 32: Fuel electrode C: Cell for SOFC

The characteristic configuration of the inter-cell connecting member according to the present invention for achieving the above object is an inter-cell connecting member having a base material and a protective film formed on the surface of the base material, An alloy containing Cr and a Si content of less than 0.39% by mass is the main material, and the protective film is ZnCoMnO ₄ as the main material.

That is, according to the above characteristic configuration, in the inter-cell connecting member having the base material and the protective film formed on the surface of the base material, the base material contains Cr and the Si content rate is 0.39 mass. The main material is an alloy that is less than 100 %, and the protective film is made of ZnCoMnO _{4. As} a result, it is possible to greatly reduce the electrical resistance of the inter-cell connecting member and realize a SOFC cell with high power generation performance. Become. When the protective film is made of ZnCoMnO ₄ as a main material, the resistance value can be reduced according to the Si content in the inter-cell connecting member configured in combination with the base material having the Si content of less than 0.39% by mass. It has been confirmed by experiments.

Claims (8)

  An inter-cell connecting member having a base material and a protective film formed on the surface of the base material, wherein the base material contains Cr, and an Si content is less than 0.39% by mass An inter-cell connecting member whose main material is spinel type metal oxide.   The inter-cell connecting member according to claim 1, wherein the Si content of the alloy is 0.30 mass% or less.   The inter-cell connection member according to claim 1 or 2, wherein the Si content of the alloy is greater than 0.15 mass%.   The inter-cell connection member according to any one of claims 1 to 3, wherein the protective film is mainly composed of a metal oxide containing Zn, Mn, and Co. 2. The main material of the protective film is Zn _x (Co _y Mn _(1-y) ) _(3-x) O ₄ (0 <x <1, 0 <y × (3-x) ≦ 2). The inter-cell connecting member according to any one of -4. The inter-cell connection member according to claim 1, wherein the protective film is mainly composed of ZnCoMnO ₄ .   The inter-cell connecting member according to claim 1, wherein the protective film is formed by electrodeposition coating.   A cell for a solid oxide fuel cell formed by joining the inter-cell connecting member according to any one of claims 1 to 7 and an air electrode.

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