JP2019102377A - Joint material and assembly - Google Patents

Abstract

To provide an assembly having a current collecting part, which is arranged so that the change in volume in oxidation and reduction can be suppressed.SOLUTION: An assembly comprising solid oxide fuel battery cells 10A, 10B, metal members 20, 20A, and current collecting parts 30 for connecting the solid oxide fuel battery cells 10A, 10B with the metal members 20, 20A is provided according to the present invention. The current collecting parts 30 each include: a primary material consisting of metal or its oxide; and a reduction expanding auxiliary material represented by the general formula, ABO(where x is 0 or 1; A includes at least one kind of lanthanoids; B includes at least one transition metal element when x is 1; and δ is a value determined so as to satisfy an electric charge neutral condition). When the total quantity of the metal of the primary material and the auxiliary material under a reduction atmosphere is 100 vol.%, the volume percentage of the metal of the primary material is 50 vol.% or more and 98 vol.% or less.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a bonding material and a bonded body.

  A single cell of a solid oxide fuel cell (SOFC: Solid Oxide Fuel Cell) has a structure in which a fuel electrode (anode), a solid electrolyte layer, and an air electrode (cathode) are stacked in this order. At the time of SOFC operation, for example, at a high temperature of 600 ° C. or higher, the oxygen-containing gas is supplied to the surface of the solid electrolyte layer on the air electrode side, and the fuel gas is supplied to the surface of the solid electrolyte layer on the fuel electrode side. It will be.

  From the viewpoint of improving the power density and the power generation efficiency, a single SOFC cell is practically used as a SOFC stack in which a plurality is electrically connected via an interconnector. The single cell of the SOFC and the interconnector are electrically connected by a current collector. The current collecting portion is conventionally formed of a material excellent in electron conductivity and durability under high temperature, for example, a metal material such as Ni, Ag, etc. (see Patent Documents 1 to 3).

JP, 2008-200724, A JP, 2008-293984, A JP, 2009-205821, A

  However, in the case where the current collecting portion on the fuel electrode side is made of the above-described metal material, the SOFC repeatedly performs operation and stop, which may cause problems such as peeling and cracks in the current collecting portion. The That is, at the time of stopping the SOFC, the fuel side current collector is exposed to air and is in an oxidizing atmosphere. On the other hand, at the time of operation of SOFC, it is exposed to fuel gas (for example, hydrogen gas) and it becomes reductive atmosphere. Due to the change from the oxidizing atmosphere to the reducing atmosphere, the metal material is reduced in the current collecting portion on the fuel side to change from an oxide state to a metal state. As a result, the volume of the metal material is reduced, and the contact area between the fuel electrode and the interconnector is reduced. In addition, when air is introduced during shutdown of the SOFC, the fuel-side current collector is exposed to an oxidizing atmosphere. As a result, in the fuel-side current collector, the metal material is oxidized to return from the metal state to the oxide state. As a result, the volume of the metallic material expands. By repetition of the above-mentioned oxidation reduction, problems such as peeling and cracks occur in the current collecting portion on the fuel side, which may lower the durability and reliability of the SOFC stack.

  This invention is made in view of this point, The objective is the joint material provided with the current collection part by which the volume change at the time of oxidation reduction was suppressed, and the jointing material which can form the above-mentioned current collection part. To provide.

According to the present invention, there is provided a joined body including a solid oxide fuel cell, a metal member, and a current collector connecting the solid oxide fuel cell and the metal member. The collector portion is a main material composed of a metal or its oxide, and a compound represented by the general formula (1): AB _x O _3-δ (where x is 0 or 1 and A is at least one lanthanoid element) And when x is 1, B contains at least one transition metal element, and δ is a value determined to satisfy the neutral condition of the charge. , And in a reducing atmosphere, the above-mentioned metal of the above-mentioned main material and the above-mentioned main material calculated based on electron microscopy-energy dispersive X-ray analysis (SEM-EDX: Scanning Electron Microscope-Energy Dispersive X-ray Spectroscope) The volume ratio of the metal of the main material is 50% by volume or more and 98% by volume or less, where the total amount with the auxiliary material is 100% by volume.

  The current collector includes a reducing / expansive secondary material in addition to the metal as a main material or the oxide thereof. Thereby, the volume change at the time of oxidation reduction can be suppressed compared with the current collection part which consists only of the conventional metal material. As a result, even if the SOFC repeats operation and stop in the current collection unit, problems such as peeling and cracking are less likely to occur. Moreover, compared with the aspect provided with the current collection part which consists only of a metal material, durability and reliability of a joined body can be improved. Therefore, the joined body provided with the above-mentioned current collection part can exhibit high power generation performance stably.

  Patent documents 2 and 3 disclose a conductive bonding material containing a perovskite oxide and a metal oxide, and a stack of a solid oxide fuel cell provided with the same. However, each of the bonding materials disclosed in Patent Documents 2 and 3 is mainly composed of a perovskite-type oxide, in which a slight amount of metal oxide coexists. Therefore, the technology disclosed herein is distinct from Patent Documents 2 and 3 in terms of, for example, the coexistence ratio of the perovskite oxide and the metal oxide.

  In a preferred embodiment disclosed herein, the main material includes at least one of Fe, Ni, Cu, Ag, Ag—Pd alloy and their oxides. These materials are excellent in the balance between cost and conductivity. Therefore, excellent conductivity and durability under high temperature can be realized relatively inexpensively.

  In a preferred embodiment disclosed herein, the auxiliary material includes the following (A), (B): (A) in the general formula (1), x is 0, and A contains at least Ce. A cerium-containing oxide; (B) a perovskite-type oxide in which x in the general formula (1) is 1; These materials are excellent in conductivity and durability under high temperature. Therefore, the effects of the technology disclosed herein can be exhibited better.

  In a preferable aspect disclosed herein, the current collection unit includes the metal and the auxiliary material of the main material calculated based on electron microscopy-energy dispersive X-ray analysis in a reducing atmosphere. The volume ratio of the metal of the main material is 80% by volume or more and 95% by volume or less, with the total of 100% by volume. Thereby, the effects of the technology disclosed herein can be exhibited at a higher level.

  In a preferred embodiment disclosed herein, the solid oxide fuel cell includes a fuel electrode, a solid electrolyte, and an air electrode, and the current collecting portion between at least the fuel electrode and the metal member. Is arranged. Since the above-mentioned current collection part is suppressed in volume change at the time of oxidation reduction, it should be suitably used on the side of the fuel electrode which is repeatedly exposed to the oxidizing atmosphere and the reducing atmosphere along with the operation and stop of the SOFC. it can.

In a preferred embodiment disclosed herein, the current collection unit has a thermal expansion coefficient E _air (%) measured in a temperature range of 25 ° C. to 700 ° C. in an oxidizing atmosphere using a thermomechanical analyzer. The volume change rate at the time of oxidation reduction calculated by subtracting the thermal expansion coefficient E _red (%) measured in the above temperature range in a reducing atmosphere is −0.01% or more and 0.18% or less. As a result, the reduction shrinkage of the main material can be better suppressed, and the effects of the technology disclosed herein can be exhibited at a higher level.

  Moreover, the jointing material used for formation of the said current collection part in manufacture of the said joined body as another aspect of this invention is disclosed. From the viewpoint of handleability and the like, the bonding material preferably contains a solvent and is prepared in the form of a paste.

1 is a perspective view schematically showing an SOFC stack according to an embodiment. 7 is a TMA measurement chart of Comparative Example 1; 7 is a TMA measurement chart of Comparative Example 4;

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings as appropriate. The matters other than the matters specifically mentioned in the specification and necessary for the implementation of the present invention (for example, the configuration of a single cell of SOFC which does not characterize the present invention, the manufacturing process of SOFC, etc.) This can be understood as a design matter of a person skilled in the art based on prior art in the field. The present invention can be implemented based on the contents disclosed in the present specification and common technical knowledge in the field. Moreover, in the following drawings, the same code | symbol is attached | subjected and demonstrated to the member and site | part which show the same effect | action, and the overlapping description may be abbreviate | omitted or simplified. In addition, dimensional relationships (length, width, thickness, etc.) in the drawings do not necessarily reflect actual dimensional relationships.

In the present specification, the “thermal expansion coefficient” means an average linear expansion coefficient α measured in a temperature range from room temperature (25 ° C.) to 700 ° C. using a thermomechanical analysis device (TMA). Say. The unit is K ⁻¹ . Unless otherwise noted, the measurement atmosphere of the thermal expansion coefficient is an oxidizing atmosphere (typically in the atmosphere, for example, an atmosphere having an oxygen partial pressure of about 0.2 atm).

The α average coefficient of linear expansion, from _{L 1} is the length of the specimen by varying the temperature _{T 1} of the test piece length _{L 0} at room temperature until _{T 2 (T 1 <T 2} ) to _{L 2} When changing, the ratio of the amount of change in length ΔL = (L ₂ −L ₁ ) to the length L ₀ at room temperature, ie, ΔL / L ₀ is taken as “thermal expansion ε”, and this thermal expansion ε is It is obtained by dividing by the difference ΔT = (T ₂ −T ₁ ). In other words, the average linear expansion coefficient α can be calculated by the following (formula I).
α = (L ₂ −L ₁ ) / {L ₀ × (T ₂ −T ₁ )}... (formula I)
The measurement of the average linear expansion coefficient α is, for example, according to JIS Z 2285: 2003 “Method of measuring linear expansion coefficient of metal material” or JIS R 1618: 2002 “Method of measuring thermal expansion by thermal mechanical analysis of fine ceramics”. It can be implemented.

Further, in the present specification, the “reduction expansion amount” means the thermal expansion coefficient E _red measured in a temperature range from room temperature (25 ° C.) to 700 ° C. in a reducing atmosphere (typically in 100% hydrogen gas). A value (E _red -E _air ) obtained by subtracting the thermal expansion coefficient E _air (%) measured in the above temperature range in an oxidizing atmosphere from (%). And, in the present specification, that this value exceeds 0%, in other words, that E _red > E _air is referred to as “having reduction expansivity”. The thermal expansion coefficient E is a value obtained by multiplying the above-mentioned thermal expansion ε by 100 and converting it into a percentage.

  Moreover, in the following description, when expressing the compounding ratio (feed ratio) in the bonding material for forming the current collector, the unit of “mass%” is mainly used, and the unit of the current collector (junction layer) is used. In expressing the abundance ratio in the state, the unit of "volume%" is mainly used. Further, in the present specification, "A to B (where A and B are arbitrary values)" mean A to B, respectively, unless otherwise specified.

<SOFC stack (junction)>
First, a solid oxide fuel cell (SOFC) will be described.
FIG. 1 is a perspective view schematically showing an SOFC stack 1 according to an embodiment. The SOFC stack 1 is flat. The SOFC stack 1 includes a plurality of SOFC single cells 10A and 10B, a plurality of metal interconnectors 20 and 20A made of metal, and a first current collector 30 and a second current collector 40. The SOFC stack 1 has a stack structure in which single cells 10A and 10B of SOFCs are stacked in a predetermined stacking direction via metal interconnectors 20 and 20A. The first current collection unit 30 and the second current collection unit 40 are respectively interposed between the SOFC single cells 10A and 10B and the metal interconnectors 20 and 20A, and the SOFC single cells 10A and 10B and the metal interconnector 20 , 20A are joined. The SOFC stack 1 is an example of a junction. The SOFC stack 1 can be manufactured according to a conventionally known method.

  The configuration of the single cells 10A and 10B may be the same as in the prior art, and is not particularly limited. In this embodiment, the unit cells 10A and 10B each include a first fuel electrode 12, a second fuel electrode 14, a solid electrolyte layer 16, and an air electrode 18.

  The first fuel electrode 12 is formed thicker than the second fuel electrode 14, the solid electrolyte layer 16 and the air electrode 18. The first fuel electrode 12 has a function as a support substrate. The first fuel electrode 12 is a so-called fuel electrode support. The first fuel electrode 12 contains a conductive material. The conductive material is, for example, a nickel-based metal material (eg, nickel) containing a nickel (Ni) component. The conductive material may be, for example, a cermet of a nickel-based metal material and zirconia stabilized with a stabilizer. In that case, the ratio of the metal material to the stabilized zirconia is not particularly limited, but it is preferable that the weight ratio is approximately 90:10 to 40:60, for example, 80:20 to 45:55.

  The properties of the conductive material are not particularly limited, but are typically in the form of powder. The average particle diameter of the conductive material (the particle diameter corresponding to 50% cumulative from the particle side in the volume-based particle size distribution measured by laser diffraction / light scattering method; the same applies hereinafter) is about 0.01 to 5 μm, for example 0.1 to 2 μm. When the conductive material is a cermet of a metal material and stabilized zirconia, from the viewpoint of enhancing the homogeneity and durability of the first fuel electrode 12, the average particle sizes of both are almost equal (for example, within ± 0.5 μm) It is good.

The average thickness (length in the stacking direction) of the first fuel electrode 12 is not particularly limited, but is approximately 0.3 to 2 mm, for example, 0.5 to 1 mm. The first fuel electrode 12 is a porous body. The porosity of the first fuel electrode 12 (value calculated by dividing the void volume determined by mercury intrusion method by the apparent volume and multiplying by 100. The same applies hereinafter) is not particularly limited, but approximately 20 to 50 volumes. %, For example 30 to 40% by volume. The thermal expansion coefficient of the first fuel electrode 12 is not particularly limited, and is, for example, 11 × 10 ^{−6 to} 14 × 10 ⁻⁶ / K.

  The second fuel electrode 14 is interposed between the first fuel electrode 12 and the solid electrolyte layer 16. The second fuel electrode 14 has higher catalytic activity than the first fuel electrode 12. The second fuel electrode 14 is a so-called fuel electrode active layer. The constituent material of the second fuel electrode 14 may be the same as that of the first fuel electrode 12, or may be partially or entirely different. The second fuel electrode 14 may include the same nickel-based metal material (eg, nickel) as the first fuel electrode 12 from the viewpoint of enhancing the integrity with the first fuel electrode 12. The second fuel electrode 14 may include an oxide ion conductor, for example, stabilized zirconia, from the viewpoint of enhancing the coordination of the thermal expansion with the solid electrolyte layer 16. The average thickness of the second fuel electrode 14 is not particularly limited, but is typically smaller than that of the first fuel electrode 12 and is about 100 μm or less, for example, 20 to 50 μm. The second fuel electrode 14 is a porous body. The porosity of the second fuel electrode 14 is not particularly limited, but is typically smaller than that of the first fuel electrode 12 and is generally 5 to 30% by volume, for example 10 to 20% by volume.

  The solid electrolyte layer 16 is interposed between the second fuel electrode 14 and the air electrode 18. The solid electrolyte layer 16 has a function of separating the gas on the side of the first fuel electrode 12 and the second fuel electrode 14 and the gas on the side of the air electrode 18. The solid electrolyte layer 16 has oxygen ion conductivity. The solid electrolyte layer 16 is an oxide ion conductor. The solid electrolyte layer 16 is, for example, zirconia stabilized with a stabilizer such as yttria, such as YSZ (Yttria stabilized zirconia) or ceria doped with a dopant such as gadolinia, such as GDC (Gadolinia doped ceria) . The average thickness of the solid electrolyte layer 16 is not particularly limited, but is approximately 1 to 20 μm, for example, 3 to 10 μm. The content ratio of the stabilizer and the doping agent is not particularly limited, but preferably about 5 to 10 mol% when the entire oxide ion conductor is 100 mol%. The solid electrolyte layer 16 is densely formed from the viewpoint of preventing gas leak. The porosity of the solid electrolyte layer 16 is not particularly limited, but is approximately 0.2 to 5% by volume, for example, 0.5 to 3% by volume.

The air electrode 18 is, for example, a perovskite oxide such as a lanthanum cobaltate (LaCoO ₃ ) system, a lanthanum manganate (LaMnO ₃ ) system, a lanthanum ferrite (LaFeO ₃ ) system, or the like. The air electrode 18 is a porous body. The porosity of the air electrode 18 is not particularly limited, but is generally 5 to 50% by volume, for example 10 to 30% by volume.

  In addition, in this embodiment, although single cell 10A, 10B is 4 layer structure, respectively, it is not limited to this. In the unit cells 10A and 10B, for example, the first fuel electrode 12 and the second fuel electrode 14 may be configured by one layer having a constant porosity. Moreover, single cell 10A, 10B may further have a layer other than the above. For example, a layer for stabilizing the interface between the solid electrolyte layer 16 and the air electrode 18, for example, a reaction inhibitor containing zirconia stabilized with a stabilizer and / or ceria doped with a dopant A layer may be provided.

  The single cells 10A and 10B are so-called anode-supported cells (ASC) cells provided with the first anode 12. However, the single cells 10A and 10B may be, for example, so-called electrolyte supported cell (ESC) cells in which the solid electrolyte layer 16 is thickened, and the air electrode 18 is thickened in the so-called air It may be a polar-supported (CSC: Cathode-Supported Cell) cell. In addition, a metal support cell (MSC: Metal-Supported Cell) may be provided with a porous metal sheet on the side of the first fuel electrode 12 or the second fuel electrode 14 away from the solid electrolyte layer 16.

The metal interconnectors 20 and 20A are for electrically connecting the plurality of single cells 10A and 10B to each other. The metal interconnector 20A located at the center of FIG. 1 intervenes between the two single cells 10A and 10B to connect the single cells 10A and 10B in series. However, the metal interconnectors 20 and 20A may be arranged to connect the single cells 10A and 10B in parallel. The metal interconnectors 20 and 20A are made of, for example, nickel, stainless steel, an austenitic alloy, a ferritic alloy or the like. Metal interconnectors 20 and 20A are examples of metal members. The thermal expansion coefficient of the metal interconnects 20 and 20A is not particularly limited, but typically 10 × 10 ⁻⁶ to 15 × 10 ⁻⁶ / K, for example 10 × 10 ^{−6 to} 12 × 10 ⁻⁶ / K .

  A plurality of grooves are formed in the cell facing surface 21 on the side facing the air electrode 18 of the metal interconnectors 20 and 20A, and an oxygen-containing gas flow path 22 is provided. The oxygen-containing gas passage 22 is connected to a first gas pipe (not shown) and is in communication with a supply source of an oxygen-containing gas (for example, hydrogen gas). A plurality of grooves are formed in the cell facing surface 25 on the side facing the first fuel electrode 12 of the metal interconnects 20 and 20A, and a fuel gas flow path 26 is provided. The fuel gas flow path 26 is connected to a second gas pipe (not shown) and is in communication with a supply source of fuel gas (for example, air).

  The first current collecting unit 30 and the second current collecting unit 40 have a function of physically and electrically connecting the metal interconnectors 20, 20A and the single cells 10A, 10B. The first current collection unit 30 and the second current collection unit 40 have high bonding strength, excellent conductivity at high temperatures, are chemically stable at high temperatures, and have volume changes associated with temperature changes. Small things are required. The first current collecting unit 30 and the second current collecting unit 40 are densely formed from the viewpoint of reducing the current collection resistance. The first current collection unit 30 connects the cell facing surface 25 of the metal interconnects 20 and 20A and the first fuel electrode 12 of the single cells 10A and 10B. The 2nd current collection part 40 has connected the cell opposing surface 21 of metal interconnector 20, 20A, and the air electrode 18 of single cell 10A, 10B.

  In this embodiment, the first current collection unit 30 and the second current collection unit 40 are formed so as to cover the cell facing surfaces 21 and 25 of the metal interconnectors 20 and 20A, respectively. However, the first current collection unit 30 and the second current collection unit 40 may be formed on at least a part where the metal interconnectors 20 and 20A and the single cells 10A and 10B are in contact with each other. It is not necessary to cover the entire surface of 25.

  In addition to the above-described required properties, the first current collection unit 30 is required to have a small volume change during oxidation / reduction and be excellent in resistance to oxidation / reduction cycles (redox resistance). The first current collection unit 30 disclosed herein includes a main material and an auxiliary material. The first current collection unit 30 may be configured of a main component and an auxiliary component, and may include a third component in addition to the main component and the auxiliary component. As a 3rd component, the element contained in the peripheral member of the 1st current collection part 30, for example, aluminum (Al), silicon (Si), chromium (Cr), etc. are mentioned. The total of the main and auxiliary members in the total mass (100%) of the first current collector 30 may be approximately 20% by mass or more, typically 50% by mass or more, and preferably 70% by mass or more. .

The main material causes a redox reaction as the SOFC stack 1 starts and stops. The main material is, for example, reductively shrinkable at a high temperature of 600 ° C. or higher. That is, the main material has a property that the volume decreases when the periphery of the first current collector 30 changes from the oxidizing atmosphere to the reducing atmosphere at high temperature. In other words, the main material has the coefficient of thermal expansion E _red (%) in the reducing atmosphere and the coefficient of thermal expansion E _air (%) in the oxidizing atmosphere as follows: E _air -E _red > 0, that is, E _air > It is a material in the relation of E _red . The effect of the technology disclosed herein is that, when the difference between the E _{air of the} main material and the E _red is large, for example, E _air -E _red 0.1% 0.1%, further, E _air -E _red 00. .2% is better exhibited.

  The main material is metal or metal oxide. The type of metal of the main material is not particularly limited, but in general, the smaller the atomic number in the periodic table of the element and / or the larger the negative value of the standard electrode potential (V vs. SHE), the easier it is to be oxidized Tend. As an example of a metal which is easily oxidized, metals belonging to the third and fourth periods of the periodic table of the elements can be mentioned. In addition, as another example, for example, magnesium (Mg), aluminum (Al), titanium (in order of decreasing negative value of standard electrode potential described in Chemical Handbook (5th edition) of Maruzen Publishing Co., Ltd.) Metals such as Ti), manganese (Mn), zinc (Zn), chromium (Cr), iron (Fe), cobalt (Co), nickel (Ni), tin (Sn), lead (Pb), copper (Cu) Although it is difficult to oxidize at room temperature, it is rapidly oxidized, for example, in a temperature environment of 300 ° C. or higher. When one or more of such metal species is used as a main material, the effects of the technology disclosed herein are better exhibited. Among them, iron groups (Fe, Co, Ni) and Cu are preferable from the viewpoint of improving the conductivity, and Fe, Ni, and Cu are more preferable from the balance between cost and conductivity. In particular, from the viewpoint of enhancing the consistency with the first fuel electrode 12 and the thermal expansion, the main material is the same metal type (eg, nickel) as the first fuel electrode 12 and / or the metal interconnectors 20 and 20A It should contain the same metal species as

  Further, from the viewpoint of improving the conductivity, simple substances of noble metals such as platinum (Pt), palladium (Pd), silver (Ag) and alloys thereof, such as Ag-Pd alloy and Pt-Pd alloy, are preferable. Among them, Ag and Ag-Pd alloys are more preferable in terms of balance between cost and conductivity.

  The nature of the metal of the main material is not particularly limited, but is typically in the form of powder. The average particle size of the main material is approximately 0.01 to 5 μm, for example, 0.1 to 2 μm. The average particle size of the main material of the first current collector 30 is substantially equal to the average particle size of the conductive material of the first fuel electrode 12 from the viewpoint of enhancing the bondability and integrity with the first fuel electrode 12 ( For example, ± 0.5 μm).

The secondary material causes a redox reaction as the SOFC stack 1 starts and stops. The secondary material is reductively expandable at a high temperature of, for example, 600 ° C. or more. That is, the auxiliary material has the property of increasing in volume, contrary to the main material, when the periphery of the first current collector 30 changes from the oxidizing atmosphere to the reducing atmosphere at high temperatures. In other words, the above-described thermal expansion coefficient E _red (%) in the reducing atmosphere and the thermal expansion coefficient E _air (%) in the oxidizing atmosphere have a relationship of E _red -E _air > 0, that is, E _red > E _air It is in. From the viewpoint of better exhibiting the effects of the technology disclosed herein, it is preferable that the above-mentioned E _red and the above E _air of the auxiliary materials satisfy E _red −E _air 0.20.2%, and E _red −E It is more preferable that _air 0.4 0.4%, for example, E _red- E _air 0.4 0.42%. In addition, although not particularly limited, it becomes easy to finely adjust the volume change at the time of redox when E _red -E _air ≦ 1.5%, for example, E _red −E _air ≦ 1.0%. Because it is preferable.

The secondary material has the following general formula (1):
AB _x O _3-δ (1);
It is 1 type, or 2 or more types of compounds represented by these. This compound can exhibit high conductivity at high temperatures. In the general formula (1), x is 0 or 1. δ is a value determined to satisfy the neutral condition of charge, typically −1.2 ≦ δ ≦ 1.2, for example, −1 ≦ δ ≦ 1. The A site contains one or more of lanthanoid elements (Ln), such as lanthanum (La), cerium (Ce), samarium (Sm), neodymium (Nd), gadolinium (Gd) and the like. The A site may further contain one or more elements other than Ln. As an example of an element that can be included in the A site, a monovalent alkali metal element or a divalent alkaline earth metal element (Ae), for example, magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba) Etc.).

  In the general formula (1), when x is 1, B site is one or two or more of transition metal elements, for example, titanium (Ti), chromium (Cr), manganese (Mn), iron (Fe) Cobalt (Co), nickel (Ni), copper (Cu) and the like. The B site may further contain one or more elements other than transition metal elements. As an example of the element which may be contained in B site, it is a metal element more than trivalent, and is a metal element classified as a typical metal or a rare earth.

In a preferred embodiment, x in the general formula (1) is 0 and at least Ce is contained at the A site. That is, the secondary material has the following general formula (2):
(A ^I _y Ce _1-y ) O _3-δ (2);
Containing a cerium-containing oxide represented by
Y in the above general formula (2) is a real number satisfying 0 ≦ y <1. y is preferably 0.01 ≦ y ≦ 0.2, for example, 0.05 ≦ y ≦ 0.1. When 0 <y, A ^I is among exemplified as an element that can be included in the A site in the general formula (1) is one or more elements other than Ce. Among them, it is preferable to include one or two or more kinds of Ln, for example, Sm, Nd, Gd and the like. Here, δ is the same as in the above general formula (1).

In another preferable aspect, x in the above general formula (1) is 1. That is, the secondary material contains a perovskite oxide represented by ABO ₃ . As an example of the perovskite type oxide, LTF oxide containing La, Ti and Fe, LSTF oxide containing La, Sr, Ti and Fe, LCTF oxide containing La, Ca, Ti and Fe, La and Examples include LSC oxides containing Sr and Co, LSCF oxides containing La, Sr, Co and Fe, LSM oxides containing La, Sr and Mn, SSC oxides containing Sm, Sr and Co, etc. Be

  When x in the above general formula (1) is 1, it is preferable that the A site contains La. The A site preferably further contains a divalent alkaline earth metal such as Ca or Sr. The B site preferably contains at least one of metals belonging to the fourth period of the periodic table of the elements, for example, Ti, Fe, Co, and Ni. It is preferable to contain Ti in B site from a viewpoint of raising a reduction expansion property well. From the viewpoint of improving the conductivity, it is preferable to contain Fe at the B site.

As a preferable example of the perovskite type oxide, the following general formula (3):
_{(La 1-α Ae α)} (B I 1-β Fe β) O 3-δ ··· (3);
And the complex oxide represented by
In the above general formula (3), α is a real number satisfying 0 ≦ α <1. α is typically 0.1 ≦ α ≦ 0.7, preferably 0.2 ≦ α ≦ 0.6, for example 0.2 ≦ α ≦ 0.4. When 0 <α, Ae is, for example, Mg, Ca, Sr, Ba or the like.
Also, β is a real number satisfying 0 ≦ β <1. β is typically 0.1 <β ≦ 0.99, preferably 0.5 ≦ β ≦ 0.95, for example 0.6 ≦ β ≦ 0.9. In the case of β <1, B ¹ is one or two or more of elements other than Fe among the elements which can be included in the B site of the general formula (1). Among them, it is preferable to contain one or more transition metal elements, for example, Ti and Co. Here, δ is the same as in the above general formula (1).

  In the first current collection unit 30 disclosed herein, when the total of the occupied volume V1 of the main metal and the occupied volume V2 of the auxiliary material is 100% by volume in a reducing atmosphere, the ratio of V1 is 50 to 98% by volume. In other words, V1: V2 = 50: 50 to 98: 2. Thereby, the volume expansion at the time of oxidation reduction is suppressed. From the viewpoint of enhancing the bonding between the first current collector 30 and the metal interconnectors 20 and 20A or reducing the contact resistance, the ratio of V1 is 80 to 95% by volume, in other words, V1: V2 = More preferably, 80:20 to 95: 5. The ratio of V1: V2 can be calculated by image analysis based on the SEM-EDX image of the first current collector 30. The detailed calculation method will be described in the section of Examples. Further, the ratio of V1 to V2 can be adjusted, for example, by the mixing ratio (feed ratio) of the main material and the auxiliary material in the bonding material used to form the first current collector 30.

The thermal expansion coefficient of the first current collecting portion 30 is equivalent to that of the first fuel electrode 12 and the metal interconnectors 20 and 20A of the unit cells 10A and 10B (approximately ± 2 × 10 ⁻⁶ / K, preferably ± 1 × 10 ^{− 6} / K). The thermal expansion coefficient of the first current collection unit 30 is typically 10 × 10 ^{−6 to} 20 × 10 ⁻⁶ / K, for example, 11 × 10 ^{−6 to} 16 × 10 ⁻⁶ / K.

In the first current collection unit 30, the volume change rate at the time of oxidation and reduction is suppressed to a low level, and the redox tolerance is improved as compared with the conventional case. In the first current collecting unit 30, the volume change rate at the time of oxidation / reduction determined by subtracting the thermal expansion coefficient E _red (%) in the reducing atmosphere from the thermal expansion coefficient E _air (%) in the above-mentioned oxidizing atmosphere is It should be approximately -0.31 to + 0.19%, and more preferably -0.01% to + 0.18%. Here, the value of the volume change rate is represented by a positive value in the case of reduction contraction, and a negative value in the case of reduction expansion. The range of the volume change rate can be realized, for example, by adjusting the mixing ratio of the main material and the auxiliary material in the bonding material, the type of the main material, and the general formulas (2) and (3) of the auxiliary material. it can.

  The first current collecting unit 30 configured as described above is, for example, one in which volumetric expansion due to oxidation and reduction is suppressed as compared with a current collecting unit made of a conventional metal material. Therefore, even when the first current collection unit 30 repeats the operation and the stop of the SOFC stack 1, the compactness is suitably maintained, and the increase of the current collection resistance hardly occurs. In other words, it is excellent in resistance to the cycle of the oxidizing atmosphere and the reducing atmosphere (redox resistance). In addition, the first current collecting unit 30 is typically superior in conductivity to the conductive bonding material as described in Patent Documents 2 and 3. Therefore, the first current collection unit 30 can maintain high conductivity for a long time, and is excellent in durability and reliability.

The second current collector 40 is typically made of the same material as that of the air electrode 18, for example, a perovskite type such as lanthanum cobaltate (LaCoO ₃ ), lanthanum manganate (LaMnO ₃ ), and lanthanum ferrite (LaFeO ₃ ). It is composed of an oxide. However, the second current collector 40 may be made of the same material as the first current collector 30.

During operation of the SOFC stack 1, the temperature of the SOFC stack 1 is raised to a high temperature of approximately 600 ° C. or higher, for example, about 600 to 900 ° C. An oxygen-containing gas, such as air, is supplied to the oxygen-containing gas flow path 22 of the metal interconnects 20 and 20A. A fuel gas such as hydrogen gas (H ₂ ) is supplied to the fuel gas flow path 26 of the metal interconnects 20 and 20A. In the single cells 10A and 10B of the SOFC, oxygen is reduced at the air electrode 18 to become oxide ions. The oxide ions reach the first fuel electrode 12 and the second fuel electrode 14 through the solid electrolyte layer 16 and oxidize hydrogen to emit electrons. This generates electrical energy. That is, power generation is performed.

<Bonding material>
Next, the bonding material disclosed herein will be described. The bonding material disclosed herein can be suitably used to form the first current collector 30 of the SOFC stack 1 described above. The bonding material includes the two types of materials described above, that is, the main material and the secondary material. The bonding material disclosed herein typically has a mass ratio of main material: secondary material = 99: 1 to 64:36, where the total of the main material and the auxiliary material is 100% by mass. For example, it is preferable that it is a main material: supplementary material = 95: 5-88:12.

  The bonding material may be composed of a main material and a secondary material, and may contain other optional components in addition to the main material and the secondary material. As other optional components, various additive components generally used in this type of application can be considered. Examples of additive components include solvents, binders, dispersants, thickeners, plasticizers, sintering aids, antifoaming agents, antioxidants, preservatives, antistatic agents, pH adjusters, coloring agents (pigments, dyes Etc. is illustrated.

  In a preferred embodiment, the bonding material contains a solvent and is prepared in the form of a paste (in the form of ink, including slurry). In the following, the paste-like bonding material may be simply referred to as "paste". As a solvent, a high boiling point organic solvent having a boiling point of about 200 ° C. or higher, for example 200 to 300 ° C., is preferably used as a main component from the viewpoint of workability and storage stability. Specific examples of the high boiling point organic solvent include alcohol solvents having -OH group such as terpineol, menthanol, texanol, dihydroterpineol, benzyl alcohol and the like, 2,2,4-trimethyl-1,3-pentanediol-1- Ester solvents such as monoisobutyrate, isobornyl acetate, etc. having an ester linking group (R-C (= O) -O-R ') in the main chain, ethyl diglycol acetate, butyl glycol acetate, butyl diglycol acetate, Ether solvents such as butyl cellosolve acetate, butyl carbitol acetate, butyl carbitol etc. having an ether bond group (-C-O-C-) in the main chain, hydrocarbon solvents such as toluene and xylene, mineral spirits etc. Be Among them, alcohol solvents can be preferably used.

  As the binder, for example, those which can be evaporated and removed by heating and firing at 500 ° C. or higher can be preferably used. Specific examples of the binder include cellulose-based polymers (cellulose derivatives) such as methyl cellulose, ethyl cellulose, hydroxymethyl cellulose, hydroxyethyl cellulose and carboxymethyl cellulose; ester-based polymers such as methacrylic acid esters; polyvinyl alcohol, polyvinyl butyral, polymethyl methacrylate, poly Acrylic polymers such as butyl methacrylate; ethylene polymers such as polyethylene oxide; nitrile polymers such as polyacrylonitrile and polymethacrylonitrile; urethane polymers such as polyurethane; polyethylene, polypropylene, polyvinylidene fluoride, polyvinylidene chloride polyvinylidene And vinyl polymers such as vinyl acetate; rubbers such as styrene butadiene rubber; and the like. Among them, a cellulose-based polymer such as ethyl cellulose can be preferably used from the viewpoint of being excellent in the combustion decomposability at the time of firing and the point of environmental consideration.

  The proportions of the main material and the auxiliary material in the entire paste are not particularly limited, but from the viewpoint of achieving high density after firing, the total of the main material and the auxiliary material is approximately 50 mass% or more in mass ratio Preferably, it is 60 to 95% by mass, for example 70 to 90% by mass. The ratio of the organic solvent to the whole paste is not particularly limited, but from the viewpoint of workability at the time of applying the paste, the viewpoint of realizing the first current collecting unit 30 with high homogeneity, etc. It is good that it is -20 mass%, typically 10-15 mass%. When the paste contains a binder, the proportion of the binder in the entire paste is not particularly limited, but the mass ratio is preferably about 1 to 10% by mass, for example, 2 to 5% by mass.

  The first current collection unit 30 of the SOFC stack 1 can be formed as follows using, for example, the above-mentioned paste. That is, first, the paste is applied to the cell facing surface 25 of the metal interconnectors 20 and 20A. Next, the surfaces of the unit cells 10A and 10B on the side of the first fuel electrode 12 are superimposed on the applied paste to form a composite. The complex is dried at room temperature and then calcined at, for example, 800 to 900 ° C. Thus, a first current collecting portion 30 is formed between the first fuel electrode 12 of the unit cells 10A and 10B and the cell facing surface 25 of the metal interconnectors 20 and 20A to electrically and physically connect them. be able to. And SOFC stack 1 provided with single cell 10A, 10B, metal interconnector 20, 20A, and the 1st current collection part 30 can be obtained. The first current collecting unit 30 formed using the paste disclosed herein is excellent in redox resistance as compared with the conventional case, and an increase in current collection resistance hardly occurs even when starting and stopping are repeated. Thus, the SOFC stack 1 can stably exhibit high power generation performance over a long period of time.

  The following examples illustrate some of the embodiments of the present invention, but are not intended to limit the present invention to those shown in the specific examples.

(Test Example I)
[Preparation of bonding material]
First, NiO powder (average particle diameter: 0.5 μm) as a main material and LSTF (La _0.6 Sr _0.4 Ti _0.1 Fe _0.9 O ₃ ) powder (average particle diameter: as an auxiliary material): 0.5 μm) were prepared. Next, NiO powder and LSTF powder were mixed or used alone at a “feed ratio” shown in Table 1, to prepare a prepared powder. Next, this prepared powder, an organic solvent (alcohol type), and an organic binder (ethyl cellulose) are mixed in a mass ratio of 100: 15: 3 to form a paste-like bonding material (Examples 1 to 7). , Comparative examples 1 to 3).

[Measurement of volume change rate during oxidation reduction]
First, each bonding material prepared above is shaped so that the size after firing is 4 mm × 5 mm × 20 mm, and fired at 1100 ° C. in the air to prepare two test pieces for measurement. did. Next, thermal expansion was measured by a differential expansion method using a thermal mechanical analyzer (type: TMA 8310) manufactured by Rigaku Corporation. The thermal expansion was measured in a temperature range from room temperature (25 ° C.) to 700 ° C. in an oxidizing atmosphere (air) or a reducing atmosphere (100% H ₂ ), respectively. In addition, in FIG. 2, the TMA measurement chart of the comparative example 1 is shown as an example.

Next, the following (formula II):
Thermal expansion coefficient E (%) = {(L ₂ −L ₁ ) / L ₀ } × 100 (formula II);
Where L ₀ = L ₁ = 20 (mm), L ₂ is the length of the test piece at 700 ° C., and the coefficient of thermal expansion E _air (from 25 ° C. to 700 ° C.) in an oxidizing atmosphere (air) % And the thermal expansion coefficient E _red (%) from 25 ° C. to 700 ° C. in a reducing atmosphere (H ₂ ).
And E _red (%) was deducted from E _air (%), ie, the volume change rate (%) at the time of oxidation reduction was computed by E _air (%)-E _red (%).
The results are shown in the "volume change" column of Table 1. The values in Table 1 are shown as positive when the volume decreases (shrinks) due to a change from an oxidizing atmosphere to a reducing atmosphere, and when the volume increases (swells) due to a change from an oxidizing atmosphere to a reducing atmosphere. Is indicated by minus.

[Measurement of composition of bonding material layer]
First, a test piece whose thermal expansion was measured in a reducing atmosphere in the measurement of the volume change rate was taken out after the temperature of the thermomechanical analyzer dropped to room temperature. Next, the test piece was subjected to CP (Cross section polisher) processing to obtain a cross section, and then observed with an SEM to obtain an SEM observation image. Next, with respect to the obtained SEM observation image, elemental mapping of Ni (Ka line) and Ti (Ka line) was performed by EDX. Then, SEM-EDX images were analyzed using image processing software (Image-Pro Plus) manufactured by Nippon Roper, and the area occupied by each constituent material was calculated.

Specifically, first, the result of elemental mapping of Ni was converted (binarized) into a black and white image, and then the outline of Ni particles was traced to calculate the area of the main material (Ni particles). Similarly, after converting (binarizing) the result of elemental mapping of Ti into a black-and-white image, the contour of Ti was traced to calculate the area of the secondary material (LSTF particle). Then, the ratio of each area to the total of the area of Ni particles and the area of LSTF particles was calculated. The processing of this cross-sectioning, SEM-EDX mapping and image analysis is carried out in a plurality of fields of view (here, 3-5 fields of view in each case), and the area ratio obtained is arithmetically averaged to obtain Ni particles and LSTF particles. The volume ratio was obtained. In addition, although element mapping of Ti was performed in the case of area calculation of LSTF particle | grain here, La and Sr are also possible, for example.
The results are shown in the column "Bonding material layer (reducing atmosphere)" in Table 1.

[Measurement of bonding strength]
First, each bonding material prepared above was apply | coated to a metal plate, and it baked at 850 degreeC in air | atmosphere. As a metal plate, ferritic stainless steel used as a material of an interconnector was used. Thereby, each bonding material layer was formed on the metal plate.
Next, a cross cut test was conducted according to JIS K 5400 8.5: 1990 "Adhesiveness-Cross cut test". Specifically, first, 11 parallel cuts were made at intervals of 1 mm in each of the formed bonding material layers to form a grid pattern of 10 × 10 = 100 squares. Next, an adhesive tape was attached so as to cover the grid pattern, and was rubbed with an eraser to adhere to the bonding material layer. Next, the pressure-sensitive adhesive tape was peeled off in the direction in which the angle formed with the bonding material layer was 90 °. And bonding strength was evaluated from the ratio (peeling area ratio:%) of the mass which peeled among the total squares (100 squares) of a grid.
The results are shown in the "bond strength" column of Table 1. In Table 1, eight or more points are indicated by “◎”, 4 to 6 points by “〇”, two points by “Δ”, and 0 points by “x” in the evaluation score of the cross-cut test of the above-mentioned JIS. There is.

[Preparation of half cell]
First, a mixed powder was prepared by mixing NiO powder (average particle diameter: 0.5 μm) and 8YSZ powder (average particle diameter: 0.5 μm) at a mass ratio of 6: 4. Next, this mixed powder, an organic solvent (xylene), an organic binder, a pore-forming material (carbon), and a plasticizer, in mass ratio, 53: 24: 8.5: 10: 4.5 The resulting mixture was mixed to form a fuel electrode support paste. This fuel electrode support forming paste was formed into a sheet having a thickness of 0.5 to 1.0 mm by a doctor blade method to obtain a fuel electrode support sheet.
Next, the mass ratio of NiO powder (average particle size: 0.5 μm), 8YSZ powder (average particle size: 0.5 μm), organic solvent (terpineol), and organic binder (ethyl cellulose) is 48: It mixed so that it might become 32: 18: 2, and was set as the paste for fuel electrode layer formation. This fuel electrode layer forming paste was applied onto the fuel electrode support sheet prepared above by screen printing to form a fuel electrode layer.

Next, the 8YSZ powder (average particle diameter: 0.5 μm), an organic solvent (terpineol), and an organic binder (ethyl cellulose) are mixed so that the mass ratio is 65: 31: 4, and the electrolyte membrane is obtained. It was a paste for formation. The paste for forming an electrolyte membrane was applied on the fuel electrode layer formed above by screen printing to form an electrolyte membrane with a thickness of 10 μm.
Next, the laminated body (fuel electrode support sheet / fuel electrode layer / electrolyte film) laminated and formed above was co-fired at 1350 ° C. to prepare a half cell.

[Measurement of contact resistance]
First, each bonding material prepared above was apply | coated to the surface of the fuel electrode side of the half cell produced above by the area of □ 10 mm x 10 mm. Next, a metal interconnect made of stainless steel (SUS430) was placed on the applied bonding material, and fired at 850 ° C. Thus, a test piece in which the SOFC cell and the interconnector were integrated through the bonding material layer was produced. Next, Pt terminals are respectively attached to the fuel electrode and the metal interconnector of the test piece, and in a reducing atmosphere (at 100% H ₂ atmosphere), at a temperature of 700 ° C., between the fuel electrode and the metal interconnector The contact resistance was measured. Specifically, sweeping was performed at DC ± 10 mV and 1 mV / sec, and the contact resistance was calculated from the slope of the graph of the voltage value and the current value at that time.

The results are shown in the "contact resistance" column of Table 1. In Table 1, the case where the volume resistivity of 0.02Ω · cm ² or less "◎", a case where the volume resistivity of 0.05Ω · cm ² or less beyond the 0.02Ω · cm ² "〇" the case where the volume resistivity of 0.1 [Omega · cm ² or less beyond 0.05? · cm ² "△", a case where the volume resistivity is more than 0.1 [Omega · cm ² "×", a relatively It shows.

As shown in Table 1, the higher the preparation ratio of the NiO powder in the bonding material, the higher the proportion of Ni in the bonding material layer in a reducing atmosphere, and when the volume change rate during oxidation reduction is NiO alone It tended to approach the value of (Comparative Example 3).
Also, from the evaluation results shown in Table 1, the following configuration:
(1) A bonding material containing NiO powder and LSTF powder in a mass ratio of NiO: LSTF = 64: 36 to 99: 1 (preferably, a mass ratio of NiO: LSTF = 88: 12 to 97: 3) Using to form a bonding material layer;
(2) A bonding material layer of Ni: LSTF = 50: 50 to 98: 2 (preferably Ni: LSTF = 80: 20 to 95: 5) in volume ratio of Ni and LSTF in a reducing atmosphere is formed To do;
Thus, it was possible to offset the reduction expansion property and reduction contraction property of the bonding material layer. As a result, the volume change rate of the bonding material layer could be suppressed to the range of -0.31 to + 0.19% (preferably, +0.004 to + 0.17%). In addition, a bonding material layer having high bonding strength and low contact resistance has been realized. The reason for this is considered that the redox resistance is improved by the reduction shrinkage of the main material being canceled by the auxiliary material and the absolute value of the volume change rate of the bonding material layer being suppressed to a small value.

(Test Example II)
The same as Test Example I above except that 10 GDC (Gd _0.1 Ce _0.9 O ₂ ) was used instead of LSTF as an auxiliary material and that the “feed ratio” in the bonding material was adjusted as shown in Table 2. The evaluations of Examples 8 to 11 and Comparative Examples 4 and 5 were performed. The results are shown in Table 2. Table 2 also shows the results of Comparative Example 3 in Test Example I above. Further, FIG. 3 shows a TMA measurement chart of Comparative Example 4 as an example.

As shown in Table 2, when GDC was used in place of LSTF as the auxiliary material, the same result as in Test Example I was obtained. That is, the following configuration:
(1) forming a bonding material layer using a bonding material in which NiO powder and GDC powder are mixed at a mass ratio of NiO: GDC = 61: 39 to 99: 1;
(2) forming a bonding material layer of Ni: GDC = 50: 50 to 98: 2 by volume ratio of Ni and GDC in a reducing atmosphere;
Thus, it was possible to offset the reduction expansion property and reduction contraction property of the bonding material layer. As a result, the volume change rate could be suppressed to the range of -0.11% to + 0.19%.

(Test Example III)
The evaluations of Examples 12 to 14 were performed in the same manner as Example 5 of the above-mentioned Test Example I except that the types of the main material and the auxiliary material included in the bonding material were changed as shown in Table 3. As the LCTF as _Fukuzai, using _{La 0.8 Ca 0.2 Ti 0.1 Fe 0.9} O 3. Further, in Example 14, and Example 5 using different composition ratios _{LSTF (La 0.6 Sr 0.4 Ti 0.3} Fe 0.7 O 3). The results are shown in Table 3. Table 3 also shows the results of Example 5 in Test Example I above.

  As shown in Table 3, even when the type of metal of the main material and / or the type of perovskite oxide of the auxiliary material were changed, the effects of the technology disclosed herein were fully exhibited.

  Although the specific examples of the present invention have been described above in detail, these are merely examples and do not limit the scope of the claims. The art set forth in the claims includes various variations and modifications of the specific examples illustrated above.

  For example, although single cells 10A and 10B of SOFC shown in FIG. 1 were planar (Planar), it is not limited to this. SOFC single cells can be of various other shapes as well. For example, it may be a polygon, a cylindrical (Tubular), or a flat cylindrical in which the circumferential side of a cylinder is vertically crushed. Further, the shape and size of the metal interconnectors 20 and 20A can be appropriately changed according to the shape of the single cells 10A and 10B.

  Further, in the SOFC stack 1 shown in FIG. 1, the metal members are the metal interconnectors 20 and 20A, but the present invention is not limited to this. The metal member may be a member electrically and / or physically connected to the single cells 10A and 10B of the SOFC. The metal member may be, for example, a gas pipe or the like connected to the fuel electrodes (the first fuel electrode 12 and the second fuel electrode 14) of the unit cells 10A and 10B. In that case, the interconnector may be made of, for example, a material other than metal such as carbon or ceramic.

1 SOFC stack 10A, 10B SOFC single cell 12 1st fuel pole 20, 20A interconnector (metal member)
30, 40 Current collector

Claims (8)

A solid oxide fuel cell,
Metal members,
A current collector connecting the solid oxide fuel cell and the metal member;
Equipped with
The current collecting unit
Main material consisting of metal or its oxide,
General formula (1): AB _x O _3-δ (where, x is 0 or 1, A contains at least one lanthanoid element, and when x is 1, B is at least one transition metal element And δ is a value determined to satisfy the neutral condition of the charge.);
The metal of the main material when the total of the metal of the main material and the auxiliary material calculated on the basis of electron microscopy-energy dispersive X-ray analysis is 100% by volume under a reducing atmosphere A bonded body, wherein the volume fraction of the is 50% by volume to 98% by volume. The main material contains at least one of Fe, Ni, Cu, Ag, Ag-Pd alloy and their oxides,
The joined body according to claim 1. The said auxiliary material is the following (A), (B):
(A) A cerium-containing oxide in which x in the general formula (1) is 0 and A contains at least Ce;
(B) Perovskite-type oxides in which x in the general formula (1) is 1;
Containing at least one of
The joined body according to claim 1 or 2. In the reducing atmosphere, the current collecting unit has a total of 100% by volume of the metal of the main component and the subcomponent calculated on the basis of electron microscopy-energy dispersive X-ray analysis. The volume ratio of the metal of the main material is 80% by volume or more and 95% by volume or less.
The joined body according to any one of claims 1 to 3. The solid oxide fuel cell has a fuel electrode, a solid electrolyte, and an air electrode.
The current collector is disposed at least between the fuel electrode and the metal member,
The joined body according to any one of claims 1 to 4. The current collecting portion is measured in a temperature range from a thermal expansion coefficient E _air (%) measured in a temperature range of 25 ° C. to 700 ° C. in an oxidizing atmosphere using a thermomechanical analyzer. The volume change rate at the time of oxidation reduction determined by subtracting the thermal expansion coefficient E _red (%) is −0.01% or more and 0.18% or less.
The joined body according to any one of claims 1 to 5.   The jointing material used for formation of the current collection part in manufacture of a joined object according to any one of claims 1 to 6.   The bonding material according to claim 7, wherein the bonding material contains a solvent and is prepared in a paste form.

Images