JP6891008B2 - Ion conductive materials and solid oxide electrochemical cells - Google Patents

Description

The present invention relates to ionic conductive materials and solid oxide electrochemical cells.

In recent years, fuel cells have been attracting attention as a clean energy source. Of the fuel cells, solid oxide fuel cells (hereinafter referred to as "SOFC") that use solid ceramics as the electrolyte can utilize exhaust heat due to their high operating temperature, and are more efficient in power generation. It has the advantage of being able to obtain fuel cells, and is expected to be used in a wide range of fields from household power sources to large-scale power generation.

As a basic structure, SOFC has a structure in which a solid electrolyte layer made of ceramic is arranged between an air electrode and a fuel electrode. For example, in a flat SOFC, a single cell is formed by stacking an air electrode, a solid electrolyte layer, and a fuel electrode, and a plurality of these single cells are stacked with an interconnector or the like in between to obtain a high output.

In SOFC, oxygen in the air introduced into the air electrode receives electrons and becomes oxygen ions ( ^O2- ), and these oxygen ions move in the solid electrolyte layer and reach the fuel electrode. Oxygen ions that reach the fuel electrode electrochemically react with hydrogen, carbon monoxide, etc. contained in the fuel gas supplied to the fuel electrode, so that electrons are emitted and an electric output is obtained.

In such a power generation mechanism, the solid electrolyte layer is required to have characteristics such as high oxygen ion conductivity and high material strength. Therefore, the solid electrolyte layer generally contains _{zirconia (yttria-stabilized zirconia (YSZ)) to which yttria (Y 2} O ₃ ) is added and zirconia (scandia-stabilized) to which scandia (Sc ₂ O ₃ ) is added. A sintered body such as a zirconia-based oxide such as zirconia (ScSZ)) is used. _{For example, Patent Document 1 states that 5 to 15 mol% of scandia (Sc 2} O ₃ ) is used as a material for a solid electrolyte layer that enables the realization of a stable crystal phase in addition to high oxygen ion conductivity and high material strength. A material has been proposed in which a solid solution of zirconia (scandia-stabilized zirconia (ScSZ)) contains a rare earth oxide other than scandia in the range of 0.5 to 5 mol%.

Further, in recent years, it has been proposed to use a cell having a basic structure similar to that of SOFC as a solid oxide fuel cell (SOEC). SOEC is a cell whose operating principle is the reverse reaction of SOFC, and is a cell that obtains hydrogen and oxygen by electrolyzing high-temperature water vapor. As for SOEC, as with SOFC, it is desirable that the solid electrolyte layer has characteristics such as high oxygen ion conductivity and high material strength. Therefore, a material suitable for the SOFC solid electrolyte layer can also be suitably used as a material for the SOEC solid electrolyte layer. The cells capable of functioning as SOFC and SOEC are generally called solid oxide-type electrochemical cells.

Japanese Unexamined Patent Publication No. 2000-340240

As one means for increasing the power generation efficiency of SOFC, there is a method of increasing the fuel usage rate, that is, the fuel utilization rate. However, since the fuel gas supplied to the fuel electrode of SOFC contains a large amount of hydrogen or carbon monoxide, if the fuel utilization rate is increased, the vicinity of the interface with the fuel electrode in the solid electrolyte layer, and further at the fuel electrode, The amount of water vapor or carbon dioxide generated by the reaction between oxygen ions and hydrogen or the reaction between oxygen ions and carbon monoxide increases, and as a result, the water vapor concentration or carbon dioxide concentration in the fuel gas increases. When the water vapor concentration and carbon dioxide concentration in the fuel gas increase, it becomes difficult for hydrogen and carbon monoxide, which are fuels, to reach the reaction field sufficiently. As a result, a part of hydrogen or carbon monoxide oxidizes the material of the fuel electrode (for example, Ni) to generate an oxide (NiO when the material of the fuel electrode is Ni), and the conductivity of the fuel electrode Is reduced and the internal resistance of the electrode is increased, so that the output is reduced, that is, the current-voltage characteristics are deteriorated. Further, due to an increase in the water vapor concentration and the carbon dioxide concentration in the fuel gas, the resistance of the fuel electrode increases and the output decreases, and the progress of deterioration of the fuel electrode and the solid electrolyte layer is promoted. For these reasons, increasing the fuel utilization rate causes a problem that the battery performance of the SOFC deteriorates.

Further, even in the case of SOEC, in order to perform electrolysis of water with high efficiency, the hydrogen electrode (the electrode corresponding to the fuel electrode of SOFC) comes into contact with high-concentration water vapor, and comes into contact with high-concentration water vapor. As a result, deterioration of the fuel electrode (hydrogen electrode) and the solid electrolyte layer leads to deterioration of cell performance.

Therefore, the present invention provides a high-output SOFC capable of achieving high current-voltage characteristics even when the water vapor concentration in the fuel gas is high due to a high fuel utilization rate, and a fuel electrode (hydrogen) capable of realizing an SOIC having excellent performance. It is an object of the present invention to provide an ionic conductive material that can be used for a (pole) and a solid electrolyte layer. Further, the present invention provides a high output SOFC capable of achieving high current-voltage characteristics and a solid oxide capable of functioning as an SOEC having excellent performance even when the water vapor concentration in the fuel gas becomes high due to a high fuel utilization rate. It is also an object to provide a form electrochemical cell.

The first aspect of the present invention is
An ionic conductive material containing a zirconia oxide,
The zirconia oxide contains Yb in the range of 6 mol or more and 30 mol or less with respect to 100 mol of Zr, and contains rare earth elements other than ytterbium in the range of 0.005 mol or more and 8 mol or less with respect to 100 mol of Zr. Includes
The zirconia-based oxide has a crystal structure having a cubic crystal as a main phase.
An ionic conductive material is provided.

A second aspect of the present invention is
A solid oxide-type electrochemical cell comprising an air electrode (including an oxygen electrode), a fuel electrode (including a hydrogen electrode), and a solid electrolyte layer arranged between the air electrode and the fuel electrode. There,
The solid electrolyte layer contains a zirconia-based oxide and
The zirconia oxide contains Yb in the range of 6 mol or more and 30 mol or less with respect to 100 mol of Zr, and contains rare earth elements other than ytterbium in the range of 0.005 mol or more and 8 mol or less with respect to 100 mol of Zr. Includes
The zirconia-based oxide has a crystal structure having a cubic crystal as a main phase.
A solid oxide-type electrochemical cell is provided.

A third aspect of the present invention is
A solid oxide-type electrochemical cell comprising an air electrode (including an oxygen electrode), a fuel electrode (including a hydrogen electrode), and a solid electrolyte layer arranged between the air electrode and the fuel electrode. There,
The fuel electrode contains a zirconia-based oxide and
The zirconia oxide contains Yb in the range of 6 mol or more and 30 mol or more with respect to 100 mol of Zr, and contains rare earth elements other than ytterbium in the range of 0.005 mol or more and 8 mol or less with respect to 100 mol of Zr. Includes
The zirconia-based oxide has a crystal structure having a cubic crystal as a main phase.
A solid oxide-type electrochemical cell is provided.

High fuel utilization by using the ionic conductive material according to the first aspect of the present invention as an electrolyte component of a fuel electrode (including a hydrogen electrode) of a solid oxide-type electrochemical cell and / or a material of a solid electrolyte layer. It is possible to realize a high-output SOFC that can realize high current and voltage characteristics even when the water vapor concentration in the fuel gas becomes high depending on the rate, and a solid oxide-type electrochemical cell that can function as a SOEC having excellent performance. Further, the solid oxide-type electrochemical cell according to the second aspect and the third aspect of the present invention has a high current-voltage characteristic that can realize a high current-voltage characteristic even when the water vapor concentration in the fuel gas increases due to the high fuel utilization rate. It can function as an output SOFC and an SOEC with excellent performance.

Cross-sectional view showing a single cell for SOFC which is an example of a solid oxide fuel cell electrochemical cell according to an embodiment of the present invention.

(Embodiment 1)
An embodiment of the ionic conductive material of the present invention will be specifically described.

The ionic conductive material of this embodiment contains a zirconia-based oxide. This zirconia oxide contains Yb in the range of 6 mol or more and 30 mol or less with respect to 100 mol of Zr, and contains rare earth elements other than ytterbium in the range of 0.005 mol or more and 8 mol or less with respect to 100 mol of Zr. Including. Further, this zirconia-based oxide has a crystal structure having a cubic crystal as a main phase. Here, in the present specification, "a zirconia-based oxide containing Yb in the range of 6 mol or more and 30 mol or less with respect to 100 mol of Zr" means that the number of Yb atoms in the zirconia-based oxide is 100 Zr atoms. It means that it is 6 mol or more and 30 mol or less with respect to mol. Further, in the present specification, "the zirconia oxide contains a rare earth element other than ytterbium within the range of 0.005 mol or more and 8 mol or less with respect to 100 mol of Zr" means that the zirconia oxide contains other than ytterbium. It means that the total amount of rare earth elements in the above is 0.005 mol or more and 8 mol or less with respect to 100 mol of Zr. That is, for example, when the zirconia oxide contains two or more rare earth elements other than ytterbium, the amount of the rare earth element means the total amount of the two or more rare earth elements. In the following description in the present specification, the amounts of rare earth elements other than ytterbium in the zirconia oxide with respect to 100 mol of Zr are all the same.

The ionic conductive material of the present embodiment can be used, for example, as an electrolyte component of a fuel electrode of a solid oxide-type electrochemical cell and / or a material of a solid electrolyte layer. In the present embodiment, the term "fuel electrode" of the solid oxide-type electrochemical cell is used to mean that it also includes "hydrogen electrode", but hereinafter, for convenience, it is simply described as "fuel electrode". Further, although the term "air electrode" of the solid oxide-type electrochemical cell is used in the sense of including "oxygen electrode", hereinafter, for convenience, it is simply described as "air electrode".

The fuel electrode and / or the solid electrolyte layer formed by using the ionic conductive material of the present embodiment can suppress deterioration when exposed to an atmosphere having a high water vapor concentration. Therefore, the ionic conductive material of the present embodiment has a high output SOFC capable of achieving high current-voltage characteristics and excellent performance even when the water vapor concentration in the fuel gas is high due to a high fuel utilization rate. It is possible to realize a solid oxide-type electrochemical cell that can function as a SOEC.

In order to more reliably realize the above effect, the ionic conductive material of the present embodiment preferably contains 90% by mass or more of the zirconia-based oxide, more preferably 95% by mass or more, and substantially the above. It is particularly preferably composed of a zirconia-based oxide. The phrase "the ionic conductive material of the present embodiment is substantially composed of the above zirconia oxide" does not mean that the ionic conductive material contains components other than the above zirconia oxide except for impurities that are unavoidable in production. This means that the zirconia-based oxide is contained in an amount of 98% by mass or more. The ionic conductive material of the present embodiment may consist only of the above-mentioned zirconia-based oxide.

The ionic conductive material of the present embodiment may contain components other than the above-mentioned zirconia-based oxide. The ionic conductive material of the present embodiment may contain a component that functions as a sintering aid, and may contain, for example, aluminum oxide (Al ₂ O ₃ ), titanium oxide (TIO ₂ ), and the like.

The form of the ionic conductive material in the present embodiment is not particularly limited, and includes all forms such as powder and sintered body.

As described above, the zirconia-based oxide in the present embodiment contains Yb in the range of 6 mol or more and 30 mol or less with respect to 100 mol of Zr. When the zirconia oxide contains itterbium (Yb) within the above range, the ionic conductive material of the present embodiment is used as an electrolyte component of the fuel electrode of the solid oxide electrochemical cell and / or as a material of the solid electrolyte layer. If this is the case, the reaction resistance can be suppressed while achieving high ionic conductivity, so that a high-performance cell with low internal resistance can be obtained. The zirconia-based oxide preferably contains ytterbium (Yb) in an amount of 12 mol or more, more preferably 13 mol or more, based on 100 mol of Zr. On the other hand, the zirconia-based oxide preferably contains ytterbium (Yb) in an amount of 28 mol or less, more preferably 25 mol or less, based on 100 mol of Zr. The content form of ytterbium (Yb) in the zirconia oxide is not particularly limited, but it is preferably dissolved in zirconium oxide.

As described above, the zirconia-based oxide in the present embodiment further contains a rare earth element other than ytterbium. Examples of rare earth elements other than ytterbium include lanthanoid elements such as Ce and Er, and at least one element selected from the group consisting of Y and Sc. Among them, at least one element selected from the group consisting of Y, Sc, Ce, Er, Lu, Tm, Nd and Ho is preferable. The content form of the rare earth element other than ytterbium in the zirconia oxide is not particularly limited, but it is preferably dissolved in zirconium oxide.

The zirconia-based oxide in the present embodiment contains a rare earth element other than ytterbium in the range of 0.005 mol or more and 8 mol or less with respect to 100 mol of Zr. When the zirconia oxide contains a rare earth element other than ytterbium within the above range, the crystal phase tends to be a stable cubic crystal. Therefore, even if the electrochemical reaction is carried out under the condition of high fuel utilization rate, that is, the condition containing a large amount of water vapor and carbon monoxide, high ionic conductivity can be maintained for a long period of time. Therefore, it is possible to suppress the deterioration of the performance of the electrochemical cell due to the deterioration of the material. The zirconia oxide preferably contains a rare earth element other than ytterbium in an amount of 0.01 mol or more, more preferably 0.02 mol or more, based on 100 mol of Zr. On the other hand, the zirconia oxide preferably contains 7 mol or less of a rare earth element other than ytterbium with respect to 100 mol of Zr, and more preferably 5 mol or less.

As described above, the zirconia-based oxide in the present embodiment has a crystal structure having cubic crystals as the main phase. When a zirconia oxide has a crystal structure having a cubic crystal as a main phase, each peak intensity is obtained from the X-ray diffraction pattern of the zirconia oxide, and each intensity value and the cubic crystal ratio (%) obtained from the following formula are obtained. ) Is 50% or more. The zirconia-based oxide having a cubic crystal as the main phase preferably has a cubic crystal ratio of 90% or more, more preferably 95% or more, and further preferably 97% or more.
Cubic crystal ratio (%) = (100-monoclinic crystal ratio) x [c (400)] ÷ [t (400) + t (004) + c (400)]
[In the formula, c (400) indicates the peak intensity of the cubic (400) plane, t (400) indicates the peak intensity of the tetragonal (400) plane, and t (004) indicates the peak intensity of the tetragonal (004) plane. Shows peak intensity]

The ionic conductive material of the present embodiment can be produced by, for example, the following method. Here, a case where the ionic conductive material is a powder made of a zirconia-based oxide will be described as an example.

The zirconia-based oxide powder can be produced, for example, by using the coprecipitation method. For example, a ytterbium compound (for example, ytterbium chloride), a compound of a rare earth element other than ytterbium (for example, chloride), and a zirconium compound (for example, zirconium chloride) are subjected to Yb of 6 mol or more and 30 mol or less based on 100 mol of Zr after firing. Rare earth elements other than Yb were mixed at a ratio of 0.005 mol or more and 8 mol or less with respect to 100 mol of Zr so as to form a zirconia-based oxide, and water was added as a solvent to the obtained mixture. A mixed aqueous solution in which a ytterbium compound, a rare earth element compound, and a zirconium compound is dissolved is prepared. Next, a co-precipitant (for example, aqueous ammonia) is added to this mixed aqueous solution, the obtained precipitate is washed and dried, and then calcined, and the obtained powder is crushed to obtain a raw material powder. The obtained raw material powder is pulverized by a ball mill treatment or the like and then calcined to obtain a zirconia oxide powder. The particle size of the obtained zirconia-based oxide powder may be appropriately adjusted according to the intended use. Here, the average particle size of the powder is a value measured by a laser diffraction / scattering type particle size distribution measuring device, and the average particle size is the median size obtained from the volume-based cumulative particle size distribution, that is, the volume accumulation is 50%. It is a particle size (D50) corresponding to. Hereinafter, unless otherwise specified, the average particle size of the powder specified in the present specification is a value obtained by the same method.

Using the ionic conductive material of the present embodiment, it is possible to prepare a fuel electrode and / or a solid electrolyte layer of a solid oxide-type electrochemical cell. That is, the method for producing a solid oxide-type electrochemical cell using the ion conductive material of the present embodiment is, for example,
A method for producing a solid oxide-type electrochemical cell including an air electrode, a fuel electrode, and a solid electrolyte layer arranged between the air electrode and the fuel electrode, wherein the fuel electrode and the fuel electrode are provided. A method for producing a solid oxide-type electrochemical cell, wherein the ionic conductive material of the present embodiment is used in the step of producing at least one of the solid electrolyte layers.
Can be specified. The fuel electrode here refers to a fuel electrode portion in contact with the solid electrolyte layer. Therefore, when the fuel electrode is composed of the fuel electrode support substrate and the fuel electrode layer as in the fuel electrode support type cell which is an example of the SOFC single cell described later, the fuel electrode is arranged on the solid electrolyte layer side. The ionic conductive material of the present embodiment is used to prepare the layer. Hereinafter, a method for producing a solid oxide-type electrochemical cell using the ionic conductive material of the present embodiment will be described. Here, as an example, a method for manufacturing a single cell for SOFC will be described.

First, an example of a single cell for SOFC manufactured by using the ionic conductive material of the present embodiment will be described. The SOFC single cell produced by using the ion conductive material of the present embodiment may be an electrolyte-supported cell or a fuel electrode-supported cell, and the type thereof is not particularly limited. Here, the case of the fuel electrode support type cell will be described as an example with reference to FIG.

FIG. 1 shows a cross-sectional view of a single cell 1 for SOFC, which is a fuel electrode support type cell. The SOFC single cell 1 includes a fuel electrode 11, an air electrode 12, and a solid electrolyte layer 13 arranged between the fuel electrode 11 and the air electrode 12. A barrier layer 14 is further provided between the solid electrolyte layer 13 and the air electrode 12. The barrier layer 14 may not be provided because it may be provided as needed.

The fuel electrode 11 is formed by a fuel electrode support substrate 111 and a fuel electrode layer 112 arranged on a surface of the fuel electrode support substrate 111 on the solid electrolyte layer 13 side. If the fuel electrode support substrate 111 itself can sufficiently act as an electrode, the fuel electrode layer 112 may not be provided. The solid electrolyte layer 13, the barrier layer 14, and the air electrode 12 are supported by the fuel electrode support substrate 111.

An example of a method for producing a single cell 1 for SOFC, which is a fuel electrode support type cell, includes a step of producing a multilayer fired body containing a fuel electrode 11, a solid electrolyte layer 13 and a barrier layer 14 and having a predetermined shape. This is a method including a step of forming an air electrode 12 on a surface opposite to the fuel electrode 11 in a multilayer fired body having a predetermined shape.

The multi-layer fired body is
(1) On the green sheet for the fuel electrode support substrate 111, a green layer for the fuel electrode layer 112 (unnecessary when the configuration does not provide the fuel electrode layer 112), a green layer for the solid electrolyte layer 13, and a barrier. A method of forming a laminated body in which a green layer for the layer 14 (unnecessary in the case of a configuration in which the barrier layer 14 is not provided) and the layers 14 are stacked in this order, and then firing the entire layer at once.
Or
(2) The green sheet for the fuel electrode support substrate 111 is fired to prepare the fuel electrode support substrate 111, and the green layer for the fuel electrode layer 112 is formed on the green sheet (unnecessary in the case of a configuration in which the fuel electrode layer 112 is not provided). After forming a laminate in which the green layer for the solid electrolyte layer 13 and the green layer for the barrier layer 14 (unnecessary in the case of a configuration in which the barrier layer 14 is not provided) are stacked in this order, these are fired. Method,
Can be produced using. Here, a method for producing a multi-layer fired body will be described by taking the method (1) as an example.

First, a green sheet for the fuel electrode support substrate 111 is prepared. The green sheet for the fuel electrode support substrate 111 is prepared by mixing the raw material powder for the fuel electrode support substrate for SOFC, the pore forming agent, the binder and the solvent, and further adding a dispersant, a plasticizer and the like as necessary. To prepare a slurry, the slurry is formed into a sheet having a predetermined thickness by an arbitrary method such as a doctor blade method, a calendar roll method, an extrusion method, etc., and this is dried to volatilize and remove the solvent. can get. The fuel electrode support substrate 111 contains a conductive component for imparting conductivity and a ceramic substance (electrolyte component) as a skeleton component. Therefore, the raw material powder for the fuel electrode support substrate includes a material for the conductive component and a material for the skeleton component. As the material for the conductive component and the material for the skeleton component, a material for the conductive component for the fuel electrode support substrate for SOFC and a material known as the material for the skeleton component can be used, respectively. It is also possible to use the ionic conductive material of the present embodiment as a material for a skeleton component for a fuel electrode support substrate. The pore-forming agent, binder, solvent, dispersant, plasticizer and the like used for producing the green sheet for the fuel electrode support substrate 111 are the pore-forming agents, binders and the like known in the method for producing the fuel electrode support substrate of SOFC. It can be appropriately selected from a solvent, a dispersant, a plasticizer, and the like. The green sheet for the fuel electrode support substrate 111 may be formed so that the thickness of the fuel electrode support substrate 111 becomes the desired thickness after firing.

A green layer for the fuel electrode layer 112 is formed on the green sheet for the fuel electrode support substrate 111 by using the paste for the fuel electrode layer 112. The paste for the fuel electrode layer 112 is prepared by mixing a raw material powder for the fuel electrode layer for SOFC, a pore forming agent, a binder and a solvent, and further adding a dispersant, a plasticizer and the like as necessary. , Prepared. This paste is applied onto the green sheet for the fuel electrode support substrate 111 by a method such as screen printing and dried to form a green layer for the fuel electrode layer 112. The fuel electrode layer 112 contains a conductive component for imparting conductivity and a ceramic substance (electrolyte component) as a skeleton component. Therefore, the raw material powder for the fuel electrode layer used for forming the green layer for the fuel electrode layer 112 includes a material for the conductive component and a material for the skeleton component. As the material for the conductive component, a material known as a material for the conductive component for the fuel electrode layer for SOFC can be used. Further, the ionic conductive material of the present embodiment is used as the material for the skeleton component for the fuel electrode layer. The material for the skeleton component for the fuel electrode layer may further contain a material other than the ionic conductive material of the present embodiment, but the power generation is performed under conditions where the concentration of water vapor or carbon dioxide is high. In order to realize high current-voltage characteristics, it is preferable to use only the ionic conductive material of the present embodiment as the material for the skeleton component for the fuel electrode layer. Further, the pore-forming agent, the binder, the solvent, the dispersant, the plasticizer and the like are appropriately selected from the pore-forming agents, the binder, the solvent, the dispersant, the plasticizer and the like known in the method for producing the fuel electrode layer of SOFC. You can choose. The green layer for the fuel electrode layer 112 may be formed so that the thickness of the fuel electrode layer 112 becomes the desired thickness after firing.

The green layer for the solid electrolyte layer 13 is formed on the green layer for the fuel electrode layer 112 by using the paste for the solid electrolyte layer 13. The paste for the solid electrolyte layer 13 is prepared by mixing at least the powder of the ionic conductive material of the present embodiment and a solvent. The paste for the solid electrolyte layer 13 may further contain an ionic conductive material other than the ionic conductive material of the present embodiment, but it may be generated under conditions where the concentration of water vapor or carbon dioxide is high. In order to realize high current-voltage characteristics, it is preferable to contain only the ionic conductive material of the present embodiment as an electrolyte component. The solvent used for the paste for the solid electrolyte layer 13 is not particularly limited, and can be appropriately selected from the solvents known in the method for producing the solid electrolyte layer of a single cell for SOFC. The green layer for the solid electrolyte layer 13 may be formed so that the thickness of the solid electrolyte layer 13 after firing becomes the desired thickness.

In addition to the powder and solvent of the ion conductive material of the present embodiment, a binder, a dispersant, a plasticizer, a surfactant, a defoaming agent and the like may be added to the paste for the solid electrolyte layer 13. The binder, dispersant and plasticizer are the binder, dispersant, plasticizer and surfactant known in the method for producing a solid electrolyte layer of a single cell for SOFC according to the material of the solid electrolyte layer 13 to be formed. , Antifoaming agent, etc. can be appropriately selected.

A green layer for the barrier layer 14 is formed on the green layer for the solid electrolyte layer 13. As for the green layer for the barrier layer 14, similarly to the fuel electrode layer 112 and the solid electrolyte layer 13, a paste containing the raw material powder constituting the barrier layer 14 is prepared and applied onto the green layer for the solid electrolyte layer 13. It can be formed by drying. As the raw material powder constituting the barrier layer 14, a material known as a material for the barrier layer of a single cell for SOFC can be used.

The green layer for the fuel electrode layer 112, the green layer for the solid electrolyte layer 13, and the green layer for the barrier layer 14 are sequentially stacked on the green sheet for the fuel electrode support substrate 111. The laminate is fired all at once. The firing temperature of the laminate is not particularly limited, but is preferably 1100 ° C. or higher, more preferably 1200 ° C. or higher, and even more preferably 1250 ° C. or higher. The firing temperature is preferably 1500 ° C. or lower, more preferably 1450 ° C. or lower, and even more preferably 1400 ° C. or lower. The firing time at the time of firing is not particularly limited, but is preferably 0.1 hour or more, more preferably 0.5 hours or more, still more preferably 1 hour or more. The firing time is preferably 10 hours or less, more preferably 7 hours or less, and even more preferably 5 hours or less.

By the above method, a multi-layer fired body can be obtained. The method for obtaining the multi-layer fired body having a predetermined shape is not particularly limited, but in consideration of shrinkage after firing, the fuel pole is placed on the green sheet for the fuel pole support substrate 111 so as to have the desired shape after firing. The laminate formed by sequentially stacking the green layer for the layer 112, the green layer for the solid electrolyte layer 13, and the green layer for the barrier layer 14 is cut and / or punched and then fired. Alternatively, the multi-layer fired body obtained by firing the laminated body may be cut using a laser or a ceramic cutter.

Next, in the multilayer fired body having a predetermined shape, the air electrode 12 is produced on the surface opposite to the fuel electrode 11. The air electrode 12 is produced by forming a green layer for the air electrode 12 using the paste for the air electrode 12 and firing it. The paste for the air electrode 12 is prepared by uniformly mixing the raw material powder, the binder and the solvent constituting the air electrode 12 together with a pore forming agent, a dispersant, a plasticizer and the like, if necessary. The raw material powder, binder, solvent, pore-forming agent, dispersant, plasticizer and the like constituting the air electrode 12 are air electrode materials, binders, solvents, pores and the like known in a method for producing an air electrode of a single cell for SOFC. It can be appropriately selected from a forming agent, a dispersant, a plasticizer and the like. The prepared paste is applied onto the multi-layer fired body by screen printing or the like and dried to form a green layer for the air electrode 12. By firing this, an air electrode 12 is produced. The firing temperature is not particularly limited, but is preferably 800 ° C. or higher, more preferably 850 ° C. or higher, and even more preferably 950 ° C. or higher. The firing temperature is preferably 1300 ° C. or lower, more preferably 1250 ° C. or lower, and even more preferably 1200 ° C. or lower. The firing time at the time of firing is not particularly limited, but is preferably 0.1 hour or more, more preferably 0.5 hours or more, still more preferably 1 hour or more. The firing time is preferably 10 hours or less, more preferably 7 hours or less, and even more preferably 5 hours or less. The green layer for the air electrode 12 is preferably formed so that the thickness of the air electrode 12 after firing becomes the desired thickness.

By the above method, the SOFC single cell 1 can be manufactured by using the ion conductive material of the present embodiment.

In this embodiment, an example of a production method using the ion conductive material of the present embodiment for both the fuel electrode (fuel electrode layer) and the solid electrolyte layer has been described, but at least one of the fuel electrode layer and the solid electrolyte layer has been described. If the ionic conductive material of the present embodiment is used for one of the productions, a single cell for SOFC with high output capable of realizing high current and voltage characteristics even in power generation under conditions of high water vapor and carbon dioxide can be manufactured. Further, although the fuel electrode support type cell has been described in the present embodiment, it goes without saying that the ion conductive material of the present embodiment can also be used for manufacturing the electrolyte support type cell.

(Embodiment 2)
An embodiment of the solid oxide electrochemical cell of the present invention will be specifically described.

The solid oxide-type electrochemical cell of the present embodiment includes an air electrode, a fuel electrode, and a solid electrolyte layer arranged between the air electrode and the fuel electrode. Hereinafter, the SOFC single cell 1 shown in FIG. 1 will be described in detail as an example of the solid oxide fuel cell electrochemical cell of the present embodiment.

As described in the first embodiment, FIG. 1 shows a cross-sectional view of a single cell 1 for SOFC, which is a fuel electrode support type cell. The SOFC single cell 1 includes a fuel electrode 11, an air electrode 12, and a solid electrolyte layer 13 arranged between the fuel electrode 11 and the air electrode 12. A barrier layer 14 is further provided between the solid electrolyte layer 13 and the air electrode 12. The barrier layer 14 may not be provided because it may be provided as needed.

The fuel electrode support substrate 111 contains a conductive component for imparting conductivity and a ceramic substance (electrolyte component) as a skeleton component. As the conductive component, those known as the conductive component of the fuel electrode support substrate of the single cell for SOFC can be included. The fuel electrode support substrate 111 may contain a ceramic material as a skeleton component known as a skeleton component of the fuel electrode support substrate of a single cell for SOFC. The fuel electrode support substrate 111 can also contain a zirconia-based oxide described as a zirconia-based oxide contained in the fuel electrode layer 112, which will be described later, as a skeleton component.

The thickness of the fuel electrode support substrate 111 is not particularly limited, but is preferably 100 μm or more, more preferably 120 μm or more, still more preferably 150 μm or more, for example. The thickness of the fuel electrode support substrate 111 is preferably 3 mm or less, more preferably 2 mm or less, further preferably 1.5 mm or less, and particularly preferably 1 mm or less. When the thickness of the fuel electrode support substrate 111 is within the above range, it becomes easy to balance the mechanical strength of the fuel electrode support substrate 111 and the gas permeability in a well-balanced manner.

The fuel electrode layer 112 contains a conductive component for imparting conductivity and a ceramic substance (electrolyte component) as a skeleton component. As the conductive component, known components such as Ni can be included as the conductive component of the fuel electrode layer of the single cell for SOFC. The fuel electrode layer 112 contains a zirconia-based oxide as a ceramic material as a skeleton component. This zirconia oxide contains Yb in the range of 6 mol or more and 30 mol or less with respect to 100 mol of Zr, and contains rare earth elements other than ytterbium in the range of 0.005 mol or more and 8 mol or less with respect to 100 mol of Zr. In addition, it has a crystal structure with cubic crystals as the main phase.

As described above, the zirconia-based oxide contained in the fuel electrode layer 112 contains Yb in the range of 6 mol or more and 30 mol or less with respect to 100 mol of Zr. When the zirconia oxide contains ytterbium (Yb) within the above range, high ionic conductivity and peeling between the zirconia-conductive component (for example, Ni) can be suppressed, so that the electrochemical cell has good current-voltage characteristics. Become. The zirconia-based oxide preferably contains 12 mol or more of Yb with respect to 100 mol of Zr, and more preferably 13 mol or more. On the other hand, the zirconia-based oxide preferably contains 28 mol or less of Yb with respect to 100 mol of Zr, and more preferably 25 mol or less. The content of ytterbium (Yb) in the zirconia-based oxide contained in the fuel electrode layer 112 is not particularly limited, but it is preferably solid-solved in zirconium oxide.

As described above, the zirconia-based oxide contained in the fuel electrode layer 112 further contains rare earth elements other than ytterbium. Examples of rare earth elements other than ytterbium include lanthanoid elements such as Ce and Er, and at least one element selected from the group consisting of Y and Sc. Among them, at least one element selected from the group consisting of Y, Sc, Ce, Er, Lu, Tm, Nd and Ho is preferable.

The zirconia-based oxide contained in the fuel electrode layer 112 contains rare earth elements other than ytterbium in the range of 0.005 mol or more and 8 mol or less with respect to 100 mol of Zr. When the zirconia oxide contains a rare earth element other than ytterbium within the above range, the crystal phase becomes cubic. Therefore, even when the electrochemical reaction is carried out under the condition of high fuel utilization rate, that is, the condition containing a large amount of water vapor and carbon monoxide, the electrochemical cell can obtain high current-voltage characteristics. The zirconia oxide preferably contains 0.01 mol or more, and more preferably 0.02 mol or more, of a rare earth element other than ytterbium with respect to 100 mol of Zr. On the other hand, the zirconia oxide preferably contains 7 mol or less of a rare earth element other than ytterbium with respect to 100 mol of Zr, and more preferably 5 mol or less. The content form of the rare earth element other than ytterbium in the zirconia oxide contained in the fuel electrode layer 112 is not particularly limited, but it is preferably solid-solved in zirconium oxide.

The zirconia-based oxide contained in the fuel electrode layer 112 has a pore ratio of 10% of pores contained only in the zirconia-based oxide when a two-dimensional image of a cross section is analyzed with a scanning electron microscope (SEM) or the like. It is preferably less than or equal to, more preferably 8% or less, further preferably 7% or less, and most preferably 5% or less. In such a case, the conduction of the oxide ion is not impaired and it is performed satisfactorily, so that a high current-voltage characteristic can be exhibited. It was confirmed that the pores contained only in the zirconia-based oxide described here are surrounded only by the zirconia-based oxide, for example, when a two-dimensional image is acquired by a device such as an SEM. Refers to the pores. The porosity of the pores contained only in the zirconia oxide is the area of the pores in the fuel electrode layer surrounded only by the zirconia oxide in the analyzed region in the acquired visual field. Can be obtained by dividing by the area of the analyzed region. For nickel oxide, zirconia oxide, and pores, when acquiring a two-dimensional image, a backscattered electron image may be acquired, or a secondary electron image and energy dispersive X-ray analysis (EDX) may be used in combination. Can be identified with.

In addition to the zirconia-based oxide, the fuel electrode layer 112 may further contain other ceramics that function as skeletal components. As another ceramic material, a material known as a material for the fuel electrode layer of a single cell for SOFC can be used.

The thickness of the fuel electrode layer 112 is not particularly limited, but is preferably 5 μm or more, more preferably 6 μm or more, still more preferably 7 μm or more, for example. The thickness of the fuel electrode layer 112 is preferably 100 μm or less, more preferably 50 μm or less, and even more preferably 30 μm or less. When the thickness of the fuel electrode layer 112 is within the above range, the electrode reaction is efficiently performed, and the battery performance becomes better when the fuel electrode support type cell is used.

The solid electrolyte layer 13 contains Yb in the range of 6 mol or more and 30 mol or less with respect to 100 mol of Zr, and contains rare earth elements other than ytterbium in the range of 0.005 mol or more and 8 mol or less with respect to 100 mol of Zr. Further, it contains a zirconia-based oxide having a crystal structure having a cubic crystal as a main phase.

As described above, the zirconia-based oxide contained in the solid electrolyte layer 13 contains Yb in the range of 6 mol or more and 30 mol or less with respect to 100 mol of Zr. When the zirconia oxide contains ytterbium (Yb) within the above range, high ionic conductivity and separation between components contained in the fuel electrode layer 112 such as zirconia-Ni can be suppressed, so that the current-voltage characteristics are good. It becomes an electrochemical cell. The zirconia-based oxide preferably contains 12 mol or more of Yb with respect to 100 mol of Zr, and more preferably 13 mol or more. On the other hand, the zirconia-based oxide preferably contains 28 mol or less of Yb with respect to 100 mol of Zr, and more preferably 25 mol or less. The content form of ytterbium (Yb) in the zirconia-based oxide contained in the solid electrolyte layer 13 is not particularly limited, but it is preferably dissolved in zirconium oxide.

As described above, the zirconia-based oxide contained in the solid electrolyte layer 13 further contains oxides of rare earth elements other than ytterbium. Examples of rare earth elements other than ytterbium include lanthanoid elements such as Ce and Er, and at least one element selected from the group consisting of Y and Sc. Among them, at least one element selected from the group consisting of Y, Sc, Ce, Er, Lu, Tm, Nd and Ho is preferable.

The zirconia-based oxide contained in the solid electrolyte layer 13 contains a rare earth element other than ytterbium in the range of 0.005 mol or more and 8 mol or less with respect to 100 mol of Zr. When the zirconia oxide contains a rare earth element other than ytterbium within the above range, high ionic conductivity and separation between zirconia and Ni can be suppressed, so that the electrochemical cell has good current-voltage characteristics. The zirconia oxide preferably contains 0.01 mol or more, and more preferably 0.02 mol or more, of a rare earth element other than ytterbium with respect to 100 mol of Zr. On the other hand, the zirconia oxide preferably contains 7 mol or less of a rare earth element other than ytterbium with respect to 100 mol of Zr, and more preferably 5 mol or less. The content of the rare earth element other than ytterbium in the zirconia oxide contained in the solid electrolyte layer 13 is not particularly limited, but it is preferably solid-solved in zirconium oxide.

The zirconia-based oxide contained in the solid electrolyte layer 13 preferably has a porosity of 10% or less, more preferably 7% or less, and 5% or less when the cross section is observed by SEM or the like. Is even more preferable. The zirconia-based oxide contained in the solid electrolyte layer 13 preferably has an average particle size of 0.8 μm or more, more preferably 0.9 μm or more, and 1.0 μm when observed by SEM or the like. The above is more preferable. In such a case, the conduction of the oxide ion is not impaired and it is performed satisfactorily, so that a high current-voltage characteristic can be exhibited.

The content ratio of the zirconia-based oxide in the solid electrolyte layer 13 may be, for example, 90% by mass or more, preferably 95% by mass or more, and more preferably 98% by mass or more. The solid electrolyte layer 13 may be made of the above-mentioned zirconia-based oxide, except for impurities that are unavoidable in production.

The solid electrolyte layer 13 may further contain a material other than the above-mentioned zirconia-based oxide. As such a material, for example, a material known as a material for the solid electrolyte layer of a single cell for SOFC can be used.

The thickness of the solid electrolyte layer 13 is not particularly limited, but is preferably 1 μm or more, more preferably 1.5 μm or more, still more preferably 2 μm or more. The thickness of the solid electrolyte layer 13 is preferably 50 μm or less, more preferably 30 μm or less, and even more preferably 20 μm or less. When the thickness of the solid electrolyte layer 13 is within the above range, the internal resistance can be reduced while preventing gas cross leakage when the fuel electrode support type cell is used. Therefore, the SOFC single cell 1 can be used. Batteries will be better. Further, the solid electrolyte layer 13 may have a single layer or a multi-layer structure.

The air electrode 12 contains an electron conductor as an essential component and an ionic conductor as an optional component. For example, the electron conductor is contained in the air electrode 12 so as to have a ratio of 25 to 100% by mass with respect to the total of the electron conductor and the ionic conductor. In order to realize the air electrode 12 having a lower electrical resistivity, the electron conductor is preferably 30% by mass or more, and 50% by mass or more, based on the total of the electron conductor and the ionic conductor. Is more desirable. However, if the electron conductor used as the air electrode has sufficient ionic conductivity (in the case of the mixed conduction band), the ionic conductor may not be included.

The electron conductor contained in the air electrode 12 is not particularly limited, and a material known as an electron conductor for the air electrode of a single cell for SOFC can be appropriately used. For example, a perovskite-type oxide having excellent electron conductivity and being stable even in an oxidizing atmosphere is preferably used.

The ionic conductor contained in the air electrode 12 is not particularly limited, and a material known as an ionic conductor for the air electrode of a single cell for SOFC can be used.

Since a known single-cell barrier layer for SOFC can be applied to the barrier layer 14, the material thereof is not particularly limited. Generally, a material having oxide ion conductivity is used for the barrier layer 14, and for example, ceria doped with an oxide of a rare earth element such as Gd, Sm, Y and Yb is used. The thickness of the barrier layer 14 is preferably 20 μm or less. If it is 20 μm or less, defects such as cracks and peeling generated in the air electrode 12 during the formation of the air electrode should be further reduced even when the difference in the coefficient of thermal expansion of the material between the air electrode 12 and the solid electrolyte layer 13 is large. Can be done. The thickness of the barrier layer 14 is more preferably 10 μm or less, further preferably 7 μm or less, and particularly preferably 5 μm or less. Further, since the barrier layer 14 can be expected to have a high effect of promoting power generation while suppressing the formation of an insulating substance that occurs between the solid electrolyte layer 13 and the air electrode 12 during cell production or in a high temperature atmosphere during power generation. The thickness is not particularly limited, but is preferably 0.1 μm or more, more preferably 0.2 μm or more, still more preferably 0.5 μm or more. The barrier layer 14 is likely to generate an insulating substance because the air electrode and the electrolyte layer are in direct contact with each other during the production of the electrochemical cell or during the reaction, and the purpose of the barrier layer 14 is to suppress the formation of the insulating substance. It is provided between the air electrode and the electrolyte layer. The barrier layer 14 may not be provided if the formation of the insulating material is sufficiently suppressed.

The SOFC single cell of the present embodiment can be manufactured by using the SOFC single cell manufacturing method described in the first embodiment.

In the present embodiment, both the fuel electrode (fuel electrode layer) and the solid electrolyte layer contain Yb in the range of 6 mol or more and 30 mol or less with respect to 100 mol of Zr, and rare earth elements other than ytterbium are contained with respect to 100 mol of Zr. An example of a single cell for SOFC containing a zirconia oxide having a crystal structure having a cubic crystal as a main phase, which is contained in the range of 0.005 mol or more and 8 mol or less, has been described. It is sufficient that at least one of the polar layer) and the solid electrolyte layer contains the above-mentioned zirconia oxide. Such a single cell for SOFC can realize high current-voltage characteristics even when the water vapor concentration in the fuel gas increases due to the high fuel utilization rate.

Ion conductivity that can be used in the fuel electrode (fuel electrode layer) in the form in which the solid electrolyte layer contains the zirconia-based oxide (corresponding to the solid oxide-type electrochemical cell according to the second aspect of the present invention). Examples of the material include zirconia oxides containing rare earth elements such as Sc, Y, and Er other than Yb, and ceria oxides containing rare earth elements such as Gd, Sm, Y, and Yb, in addition to the above zirconia oxides. , Lantangalate, and lanthanum gallate-based perovskite structural oxides in which a part of the lanthanum or gallium of the lanthanum gallate is replaced with strontium, calcium, barium, magnesium, aluminum, indium, cobalt, iron, nickel, copper, etc. can do. Further, in a form in which the fuel electrode (fuel electrode layer) contains the above-mentioned zirconia-based oxide (corresponding to the above-mentioned solid oxide-type electrochemical cell according to the third aspect of the present invention), it can be used in the solid electrolyte layer. The same applies to the ionic conductive material that can be used in place of the zirconia-based oxide.

In the above embodiment, SOFC has been described in detail as an embodiment of the solid oxide electrochemical cell of the present invention, but the solid oxide electrochemical cell of the present invention is not limited to SOFC and is designated as SOEC. Needless to say, it can also work.

Hereinafter, the present invention will be described in detail with reference to examples. The present invention is not limited to the examples shown below.

<Example 1>
(Preparation of fuel electrode support substrate green sheet)
60 parts by mass of nickel oxide (manufactured by Shodo Chemical Industry Co., Ltd., trade name "Green") as a conductive component, 40 parts by mass of 3 mol% itria stabilized zirconia powder (manufactured by Toso Co., Ltd., trade name "TZ3Y") as a skeletal component , 10 parts by mass of carbon black (manufactured by SEC Carbon Co., Ltd., SGP-3) as a pore-forming agent, a binder composed of a methacrylate-based copolymer (molecular weight: 30,000, glass transition temperature: -8 ° C., solid content concentration: 50) 30 parts by mass), 2 parts by mass of dibutylphthalate as a plasticizer, and 80 parts by mass of a mixed solvent of toluene / isopropyl alcohol (mass ratio = 3/2) as a dispersion medium were mixed by a ball mill to prepare a slurry. Using the obtained slurry, a sheet was formed by a doctor blade method and dried at 70 ° C. for 5 hours to prepare a fuel electrode support substrate green sheet. Regarding the thickness of the green sheet, a preliminary experiment was conducted using a slurry having the same composition, and the thickness of the sheet after firing was set to 400 μm in consideration of the relationship between the thickness of the green sheet and the sheet after firing. A green sheet (1) was produced under the control of the above.

(Preparation of zirconia-based oxide powder (1))
Ytterbium (III) chloride hydrate (manufactured by Wako Pure Chemical Industries, Ltd.), scandium (III) chloride hexahydrate (manufactured by Wako Pure Chemical Industries, Ltd.) and zirconium chloride (IV) (manufactured by Wako Pure Chemical Industries, Ltd.) after firing 8 Mol% ytterbium 1 mol% Scandia-stabilized zirconia (8Yb1ScSZ: (Yb ₂ O ₃ ) _0.08 (Sc ₂ O ₃ ) _0.01 (ZrO ₂ ) _0.91 , that is, for 100 mol of Zr, 18 mol of Yb and 2. It was weighed so as to be (zirconia-based oxide contained in 2 mol). Ultrapure water (resistivity: 17.5 MΩ · cm) was prepared, and the water temperature was controlled to 20 ° C. using a magnetic stirrer with a heating function to dissolve the above chloride. If it did not dissolve even after 30 minutes, ultrapure water was further added and the chloride was visually dissolved until the chloride was dissolved. After visually confirming that the chloride has been dissolved, add 10% by mass of the ultrapure water required for dissolution, and heat and keep the aqueous solution at 25 ° C. While stirring for another hour, the chloride was completely dissolved. The obtained aqueous solution was added dropwise to aqueous ammonia, and the obtained precipitate was washed and dried, and then calcined at 800 ° C. for 1 hour. Ethanol was added to the calcined powder, pulverized and mixed in a ball mill for 10 hours, dried, and further crushed in a mortar, and the crushed powder was calcined at 1200 ° C. to obtain a calcined powder. Ethanol was added to the obtained calcined powder, pulverized with a ball mill so that the average particle size was about 0.5 μm, and dried to obtain 8Yb1ScSZ powder as a zirconia-based oxide powder (1). The produced zirconia-based oxide powder (1) has 18 mol of Yb and 2.2 mol of Sc with respect to the target composition, that is, 100 mol of Zr, according to <evaluation of powder composition> described later. It was confirmed.

(Ball mill processing of powder for fuel electrode layer)
In a plastic container, 60 parts by mass of nickel oxide (Nikko Rika Co., Ltd., trade name "high-purity nickel oxide F") as a conductive component, zirconia-based oxide powder as a skeletal component and an ionic conductive component (1) ( 40 parts by mass of 8Yb1ScSZ powder) and ethanol as a dispersion medium were further added, and this was pulverized and mixed with a ball mill and then dried to obtain a mixed powder (1b) (NiO / 8Yb1ScSZ mixed powder).

(Preparation of paste (1) for fuel electrode layer)
60 parts by mass of the mixed powder (1b) obtained by the above ball mill treatment, 36 parts by mass of α-terpineol (manufactured by Wako Pure Chemical Industries, Ltd.) as a solvent, 4 parts by mass of ethyl cellulose (manufactured by Wako Pure Chemical Industries, Ltd.) as a binder, After mixing 6 parts by mass of dibutylphthalate (manufactured by Wako Pure Chemical Industries, Ltd.) as a plasticizer and 4 parts by mass of a sorbitan fatty acid ester-based surfactant as a dispersant using a dairy pot, a 3-roll mill (manufactured by EXAKT technologies) , Model "M-80S", roll material: alumina) was crushed to prepare a paste (1) for the fuel electrode layer. In this pasting process, by adjusting the gap between the three roll mills and the rotation speed, the maximum particle size measured by the grind meter described in <Evaluation of agglomerates in paste> described later is large. It was crushed / kneaded until the size became 10 μm or less.

(Ball mill treatment of electrolyte powder)
A zirconia-based oxide powder (1) and ethanol as a dispersion medium were further added to a plastic container, which was pulverized with a ball mill and then dried to obtain a ball-milled zirconia-based oxide powder (1b). In this ball mill treatment, the rotation time was adjusted to obtain a powder having an average particle size (D50) of 0.24 μm.

(Preparation of paste (1) for solid electrolyte layer)
60 parts by mass of zirconia oxide powder (1b) obtained by the above ball mill treatment, 5 parts by mass of ethyl cellulose (manufactured by Wako Pure Chemical Industries, Ltd.) as a binder, and α-terpineol (manufactured by Wako Pure Chemical Industries, Ltd.) as a solvent. 40 parts by mass, 6 parts by mass of dibutylphthalate (manufactured by Wako Pure Chemical Industries, Ltd.) as a plasticizer, and a sorbitan acid ester-based surfactant (manufactured by Sanyo Kasei Kogyo Co., Ltd., trade name "Ionet S-80") as a dispersant. After mixing 5 parts by mass using a dairy pot, it is crushed using a 3-roll mill (manufactured by EXAKT technologies, model "M-80S" roll material: alumina) to prepare a paste (1) for a solid electrolyte layer. did. In this pasting process, the size of the maximum particle size measured by the grind meter described in <Evaluation of agglomerates in paste> described later by adjusting the gap between the three roll mills and the rotation speed. Was crushed / kneaded until the value was 10 μm or less.

(Preparation of paste (1) for barrier layer)
60 parts by mass of ceria powder (manufactured by Anan Kasei Co., Ltd.) doped with 10 mol% gadlinear as a ceramic, 5 parts by mass of ethyl cellulose (manufactured by Wako Pure Chemical Industries, Ltd.) as a binder, α-terpineol as a solvent 40 parts by mass of Wako Pure Chemical Industries, Ltd., 6 parts by mass of dibutylphthalate as a plasticizer (manufactured by Wako Pure Chemical Industries, Ltd.), and sorbitanoic acid ester-based surfactant as a dispersant (manufactured by Sanyo Kasei Kogyo Co., Ltd., 5 parts by mass of trade name "Ionet S-80") was mixed using a dairy pot, and then crushed using a 3-roll mill (manufactured by EXAKT technologies, model "M-80S", roll material: alumina). As a result, the barrier layer paste (1) was obtained. In this pasting process, the size of the maximum particle size measured by the grind meter described in <Evaluation of agglomerates in paste> described later by adjusting the gap between the three roll mills and the rotation speed. Was crushed / kneaded until the value was 10 μm or less.

(Formation of green layer for fuel electrode layer)
The 8Yb1ScSZ fuel electrode layer paste (1) is printed on the fuel electrode support substrate green sheet (1) obtained above by screen printing so that the thickness after firing is 20 μm, and dried at 100 ° C. for 30 minutes. , A green layer (1) for the fuel electrode layer was formed.

(Formation of green layer for solid electrolyte layer)
The paste (1) for the solid electrolyte layer is printed on the green layer (1) for the fuel electrode layer obtained above by screen printing so that the thickness after firing is 7 μm, and dried at 100 ° C. for 30 minutes. The green layer (1) for the solid electrolyte layer was formed.

(Formation of green layer for barrier layer)
On the green layer (1) for the solid electrolyte layer obtained above, the paste (1) for the barrier layer was printed by screen printing so that the thickness after firing was 3 μm. This was dried at 100 ° C. for 30 minutes to form a green layer (1) for a barrier layer.

(Baking)
After the barrier layer green layer (1) is dried, the fuel electrode on which the barrier layer green layer (1), the solid electrolyte layer green layer (1), and the fuel electrode layer green layer (1) are formed. The support substrate green sheet (1) was punched out so that one side after firing would be a square of 60 mm. After punching, it was fired at 1300 ° C. for 2 hours to obtain a half cell (1) having a fuel electrode layer, a solid electrolyte layer and a barrier layer in this order on a fuel electrode support substrate.

The following samples of half cells (a) and (b) were also prepared for the <evaluation of crystal structure> described later. The same applies to the following examples and comparative examples.
(A) In order to investigate the "crystal structure of zirconia oxide in the solid electrolyte layer of a single cell for SOFC", the green layer for the fuel electrode layer was placed on the fuel electrode support substrate green sheet (without forming the barrier layer green layer). A sample of a half cell (a) having a fuel electrode layer and a solid electrolyte layer on the fuel electrode substrate in this order was obtained by preparing a product in which a green layer was formed and firing the mixture.
(B) In order to investigate the "crystal structure of zirconia oxide in the fuel electrode layer of a single cell for SOFC", the fuel was put on the fuel electrode support substrate green sheet (without forming the barrier layer green layer and the electrolyte layer green layer). A sample of a half cell (a) having a fuel electrode layer on a fuel electrode substrate was obtained by producing a product in which a green layer for an electrode layer was formed and firing it.

(Preparation of LSCF powder for air electrode layer)
As a powder material as a raw material for the air electrode layer, LSCF powder (1) was prepared as follows. That is, commercially available _{powders of La 2} O ₃ and SrCO _{3 having} a purity of 99.9% and CoO and Fe ₂ O _{3 having} a purity of 99% were mixed so that the element ratio was La _0.6 Sr _0.4 Co _0.2 Fe _0.8. Ethanol was added to the obtained mixture, and this was pulverized and mixed in a bead mill for 1 hour. The resulting mixture was then dried and then calcined at 800 ° C. for 1 hour. Ethanol was further added to the mixture after calcining, and the mixture was pulverized and mixed with a bead mill for 1 hour, and then dried. The mixture was then heated at 1200 ° C. for 5 hours to give a powder. Ethanol was added to the obtained powder, which was further pulverized and mixed in a ball mill for 10 hours and then dried to obtain a powder. The obtained powder was confirmed by XRD (manufactured by Spectris Co., Ltd .: X PERT-MPD) to be a single phase composed of perovskite. After that, the LSCF powder (1) having an average particle size (D50) of 0.52 μm was obtained by pulverizing while adjusting the rotation speed and the rotation time using a planetary ball mill. It was confirmed that the obtained LSCF powder had a target composition, that is, an element ratio of La _0.6 Sr _0.4 Co _0.2 Fe _0.8 by <evaluation of powder composition> described later.

(Preparation of paste (1) for air electrode layer)
To 100 parts by mass of the LSCF powder (1) prepared by the above method, add 3% by mass of ethyl cellulose as a binder and 30% by mass of α-terpineol as a solvent, and add this to a mortar. Premixed using. Then, it was kneaded using a three-roll mill (manufactured by EXAKT technologies, model "M-80S", roll material: alumina) to obtain a paste (1) for an air electrode layer.

(Formation of air pole)
The paste for the air electrode layer (1) is applied to a square of 1 cm × 1 cm by screen printing on the surface of the barrier layer of the fuel electrode support type half cell (1) having the barrier layer, and dried at 90 ° C. for 1 hour. , A green layer (1) for the air electrode layer was formed. The green layer (1) for the air electrode layer was fired at 1000 ° C. for 2 hours to form an air electrode, and a single cell (1) for SOFC according to Example 1 was obtained.

<Example 2>
In the preparation of the zirconia-based oxide powder (1) in Example 1, itterbium chloride (III) hydrate (manufactured by Wako Pure Chemical Industries, Ltd.), scandium chloride (III) hexahydrate (manufactured by Wako Pure Chemical Industries, Ltd.) and chloride. zirconium (IV) (manufactured by Wako Pure Chemical Industries, Ltd.), after firing the 7 mol% ytterbia 2 mol% scandia-stabilized zirconia _{(7Yb2ScSZ: (Yb 2 O 3} ) 0.07 (Sc 2 O 3) 0.02 (ZrO 2) 0.91, i.e. , Zirconia oxide powder (2) (2) in the same manner as in Example 1 except that the zirconia oxide containing 15 mol of Yb and 4.4 mol of Sc was measured with respect to 100 mol of Zr. 7Yb2ScSZ powder) was produced, and a single cell (2) for SOFC of Example 2 was produced in the same manner as in Example 1.

<Example 3>
In the preparation of the zirconia-based oxide powder (1) in Example 1, itterbium chloride (III) hydrate (manufactured by Wako Pure Chemical Industries, Ltd.), scandium chloride (III) hexahydrate (manufactured by Wako Pure Chemical Industries, Ltd.) and chloride. After firing zirconium (IV) (manufactured by Wako Pure Chemical Industries, Ltd.), 11 mol% ittervia 0.5 mol% scandia-stabilized zirconia (11Yb0.5ScSZ: (Yb ₂ O ₃ ) _0.11 (Sc ₂ O ₃ ) _0.005 (ZrO ₂₎ ) _0.885 , that is, a zirconia oxide containing 25 mol of Yb and 1.1 mol of Sc with respect to 100 mol of Zr), except that the zirconia oxide was measured in the same manner as in Example 1. Powder (3) (11Yb0.5ScSZ powder) was produced, and further, in the same manner as in Example 1, a single cell (3) for SOFC of Example 3 was produced.

<Example 4>
In the preparation of the zirconia-based oxide powder (1) in Example 1, yttria-stabil chloride (III) hydrate (manufactured by Wako Pure Chemical Industries, Ltd.), yttrium (III) chloride anhydride (manufactured by Wako Pure Chemical Industries, Ltd.) and zirconium chloride (manufactured by Wako Pure Chemical Industries, Ltd.) IV) (manufactured by Wako Pure Chemical Industries, Ltd.) after firing 8 mol% ittervia 1 mol% yttria-stabilized zirconia (8Yb1YSZ: (Yb ₂ O ₃ ) _0.08 (Y ₂ O ₃ ) _0.01 (ZrO ₂ ) _0.91 , that is, Zr100 Zirconia oxide powder (4) (8Yb1YSZ) in the same manner as in Example 1 except that the zirconia oxide containing 18 mol of Yb and 2.2 mol of Y was weighed with respect to the mol. Powder) was produced, and a single cell (4) for SOFC of Example 4 was produced in the same manner as in Example 1.

<Example 5>
In the preparation of the zirconia-based oxide powder (1) in Example 1, yttria-stabil chloride (III) hydrate (manufactured by Wako Pure Chemical Industries, Ltd.), cerium (III) chloride hydrate (manufactured by Wako Pure Chemical Industries, Ltd.) and zirconium chloride. (IV) (manufactured by Wako Pure Chemical Industries, Ltd.) after firing 8 mol% yttria 1 mol% ceria-stabilized zirconia (8Yb1CeSZ: (Yb ₂ O ₃ ) _0.08 (CeO ₂ ) _0.01 (ZrO ₂ ) _0.91 , that is, Zr 100 mol Zirconia oxide powder (5) (8Yb1CeSZ powder) in the same manner as in Example 1 except that the zirconia oxide containing 18 mol of Yb and 1.1 mol of Ce) was weighed. ) Was manufactured, and further, in the same manner as in Example 1, a single cell (5) for SOFC of Example 5 was prepared.

<Example 6>
In the preparation of the zirconia-based oxide powder (1) in Example 1, itterbium chloride (III) hydrate (manufactured by Wako Pure Chemical Industries, Ltd.), erbium (III) chloride anhydride (manufactured by Wako Pure Chemical Industries, Ltd.) and zirconium chloride (manufactured by Wako Pure Chemical Industries, Ltd.). IV) (manufactured by Wako Pure Chemical Industries, Ltd.) after firing 8 mol% ittervia 1 mol% erbium oxide stabilized zirconia (8Yb1ErSZ: (Yb ₂ O ₃ ) _0.08 (Er ₂ O ₃ ) _0.01 (ZrO ₂ ) _0.91 , that is, Zirconia oxide powder (6) (6) in the same manner as in Example 6 except that the zirconia oxide containing 18 mol of Yb and 2.2 mol of Er was measured with respect to 100 mol of Zr. 8Yb1ErSZ powder) was produced, and a single cell (6) for SOFC of Example 6 was produced in the same manner as in Example 1.

<Example 7>
In the preparation of the zirconia-based oxide powder (1) in Example 1, itterbium chloride (III) hydrate (manufactured by Wako Pure Chemical Industries, Ltd.), lutetium (III) chloride anhydride (manufactured by Wako Pure Chemical Industries, Ltd.) and zirconium chloride (manufactured by Wako Pure Chemical Industries, Ltd.). IV) (manufactured by Wako Pure Chemical Industries, Ltd.) after firing 8 mol% ittervia 1 mol% lutetium oxide stabilized zirconia (8Yb1LuSZ: (Yb ₂ O ₃ ) _0.08 (Lu ₂ O ₃ ) _0.01 (ZrO ₂ ) _0.91 , that is, Zirconia oxide powder (7) (7) in the same manner as in Example 1 except that the zirconia oxide containing 18 mol of Yb and 2.2 mol of Lu was measured with respect to 100 mol of Zr. 8Yb1LuSZ powder) was produced, and a single cell (7) for SOFC of Example 7 was further produced in the same manner as in Example 1.

<Example 8>
In the preparation of the zirconia-based oxide powder (1) in Example 1, itterbium chloride (III) hydrate (manufactured by Wako Pure Chemical Industries, Ltd.), thulium (III) chloride anhydride (manufactured by Wako Pure Chemical Industries, Ltd.) and zirconium chloride (manufactured by Wako Pure Chemical Industries, Ltd.) IV) (manufactured by Wako Pure Chemical Industries, Ltd.) after firing 8 mol% ittervia 1 mol% thulium oxide stabilized zirconia (8Yb1TmSZ: (Yb ₂ O ₃ ) _0.08 (Tm ₂ O ₃ ) _0.01 (ZrO ₂ ) _0.91 , that is, Zirconia oxide powder (8) (8) in the same manner as in Example 1 except that the zirconia oxide containing 18 mol of Yb and 2.2 mol of Tm was measured with respect to 100 mol of Zr. 8Yb1TmSZ powder) was produced, and a single cell (8) for SOFC of Example 8 was further produced in the same manner as in Example 1.

<Example 9>
In the preparation of the zirconia-based oxide powder (1) in Example 1, itterbium chloride (III) hydrate (manufactured by Wako Pure Chemical Industries, Ltd.), neodymium chloride (III) hexahydrate (manufactured by Wako Pure Chemical Industries, Ltd.) and chloride. Zirconium (IV) (manufactured by Wako Pure Chemical Industries, Ltd.) is fired to 8 mol% ittervia 1 mol% neodymium oxide stabilized zirconia (8Yb1NdSZ: (Yb ₂ O ₃ ) _0.08 (Nd ₂ O ₃ ) _0.01 (ZrO ₂ ) _0.91 , That is, the zirconia-based oxide powder (9) was measured in the same manner as in Example 1 except that the zirconia-based oxide containing 18 mol of Yb and 2.2 mol of Nd was measured with respect to 100 mol of Zr. ) (8Yb1NdSZ powder) was further produced, and a single cell (9) for SOFC of Example 9 was produced in the same manner as in Example 1.

<Example 10>
In the preparation of the zirconia-based oxide powder (1) in Example 1, itterbium chloride (III) hydrate (manufactured by Wako Pure Chemical Industries, Ltd.), holmium (III) chloride anhydride (manufactured by Wako Pure Chemical Industries, Ltd.) and zirconium chloride (manufactured by Wako Pure Chemical Industries, Ltd.). IV) (manufactured by Wako Pure Chemical Industries, Ltd.) after firing 8 mol% ittervia 1 mol% holmium oxide stabilized zirconia (8Yb1HoSZ: (Yb ₂ O ₃ ) _0.08 (Ho ₂ O ₃ ) _0.01 (ZrO ₂ ) _0.91 , that is, Zirconia oxide powder (10) (10) in the same manner as in Example 1 except that the zirconia oxide containing 18 mol of Yb and 2.2 mol of Ho was measured with respect to 100 mol of Zr. 8Yb1HoSZ powder) was produced, and a single cell (10) for SOFC of Example 10 was further produced in the same manner as in Example 1.

<Example 11>
In the preparation of the zirconia-based oxide powder (1) in Example 1, itterbium chloride (III) hydrate (manufactured by Wako Pure Chemical Industries, Ltd.), scandium chloride (III) hexahydrate (manufactured by Wako Pure Chemical Industries, Ltd.) and chloride. After firing zirconium (IV) (manufactured by Wako Pure Chemical Industries, Ltd.), 8 mol% ittervia 0.01 mol% scandia-stabilized zirconia (8Yb 0.01ScSZ: (Yb ₂ O ₃ ) _0.08 (Sc ₂ O ₃ ) _0.0001 (ZrO _{2) ) 0.9199} , that is, a zirconia oxide containing 17 mol of Yb and 0.022 mol of Sc with respect to 100 mol of Zr), except that the zirconia oxide was measured in the same manner as in Example 1. Powders (11) (8Yb0.01ScSZ powder) were produced, and further, in the same manner as in Example 1, a single cell (11) for SOFC of Example 11 was produced.

<Example 12>
In the preparation of the zirconia-based oxide powder (1) in Example 1, itterbium chloride (III) hydrate (manufactured by Wako Pure Chemical Industries, Ltd.), lutetium (III) chloride anhydride (manufactured by Wako Pure Chemical Industries, Ltd.) and zirconium chloride (manufactured by Wako Pure Chemical Industries, Ltd.). IV) (manufactured by Wako Pure Chemical Industries, Ltd.) after firing 8 mol% ittervia 0.02 mol% lutetium oxide stabilized zirconia (8Yb0.02LuSZ: (Yb ₂ O ₃ ) _0.08 (Lu ₂ O ₃ ) _0.0002 (ZrO ₂ ) _The zirconia oxide powder was measured in the same manner as in Example 1 except that it was measured so as to be 0.9198, that is, a zirconia oxide containing 17 mol of Yb and 0.043 mol of Lu with respect to 100 mol of Zr. (12) (8Yb0.02LuSZ powder) was produced, and further, in the same manner as in Example 1, a single cell (12) for SOFC of Example 7 was produced.

<Example 13>
In the formation of the green layer for the fuel electrode layer in Example 1, the paste was produced in the same manner as in Example 1 except that the 8Yb0.01ScSZ fuel electrode layer paste produced in Example 11 was used as the paste for the fuel electrode layer. Then, a single cell (13) for SOFC of Example 13 was obtained.

<Example 14>
In the formation of the green layer for the fuel electrode layer in Example 11, the paste was produced in the same manner as in Example 1 except that the 8Yb1ScSZ fuel electrode layer paste produced in Example 1 was used as the paste for the fuel electrode layer. , A single cell (14) for SOFC of Example 14 was obtained.

<Example 15>
In the formation of the green layer for the fuel electrode layer in Example 1, the paste was produced in the same manner as in Example 1 except that the 8Yb1YSZ fuel electrode layer paste prepared in Example 4 was used as the paste for the fuel electrode layer. , A single cell (15) for SOFC of Example 15 was obtained.

<Comparative example 1>
In the preparation of the zirconia-based oxide powder (1) in Example 1, 7 mol of yttria-stabil chloride (III) hydrate (manufactured by Wako Pure Chemical Industries, Ltd.) and zirconium chloride (IV) (manufactured by Wako Pure Chemical Industries, Ltd.) were fired. % Yttria-stabilized zirconia (7YbSZ: (Yb ₂ O ₃ ) _0.07 (ZrO ₂ ) _0.93 , that is, zirconia oxide containing 15 mol of Yb for 100 mol of Zr) Zirconia oxide powder (c1) (7YbSZ powder) was produced in the same manner as in Example 1, and a single cell (c1) for SOFC of Comparative Example 1 was further produced in the same manner as in Example 1. That is, the zirconia-based oxide powder (c1) of Comparative Example 1 did not contain oxides of rare earth elements other than ytterbium.

<Comparative example 2>
In the preparation of the zirconia-based oxide powder (1) in Example 1, 11 mol of yttria-stabil chloride (III) hydrate (manufactured by Wako Pure Chemical Industries, Ltd.) and zirconium chloride (IV) (manufactured by Wako Pure Chemical Industries, Ltd.) were added after firing. % Yttria-stabilized zirconia (11YbSZ: (Yb ₂ O ₃ ) _0.11 (ZrO ₂ ) _0.89 , that is, zirconia oxide containing 25 mol of Yb for 100 mol of Zr) A zirconia-based oxide powder (c2) (11YbSZ powder) was produced in the same manner as in Example 1, and a single cell (c2) for SOFC of Comparative Example 2 was further produced in the same manner as in Example 1. That is, the zirconia-based oxide powder (c2) of Comparative Example 2 did not contain oxides of rare earth elements other than ytterbium.

<Comparative example 3>
In the preparation of the zirconia-based oxide powder (1) in Example 1, itterbium chloride (III) hydrate (manufactured by Wako Pure Chemical Industries, Ltd.), scandium chloride (III) hexahydrate (manufactured by Wako Pure Chemical Industries, Ltd.) and chloride. After firing zirconium (IV) (manufactured by Wako Pure Chemical Industries, Ltd.), 8 mol% ittervia 4 mol% scandia-stabilized zirconia (8Yb4ScSZ: (Yb ₂ O ₃ ) _0.08 (Sc ₂ O ₃ ) _0.04 (ZrO ₂ ) _0.88 , that is, , Zrconia oxide powder (c3) in the same manner as in Example 1 except that the zirconia oxide containing 18 mol of Yb and 9.1 mol of Sc was measured with respect to 100 mol of Zr. (8Yb4ScSZ powder) was produced, and further, in the same manner as in Example 1, a single cell (c3) for SOFC of Comparative Example 3 was produced. That is, the zirconia-based oxide powder (c3) of Comparative Example 3 contained a rare earth element other than ytterbium in an amount of more than 8 mol with respect to 100 mol of Zr.

<Comparative example 4>
In the preparation of the zirconia-based oxide powder (1) in Example 1, itterbium chloride (III) hydrate (manufactured by Wako Pure Chemical Industries, Ltd.), scandium chloride (III) hexahydrate (manufactured by Wako Pure Chemical Industries, Ltd.) and chloride. After firing zirconium (IV) (manufactured by Wako Pure Chemical Industries, Ltd.), 7 mol% ittervia 5 mol% scandia-stabilized zirconia (7Yb5ScSZ: (Yb ₂ O ₃ ) _0.07 (Sc ₂ O ₃ ) _0.05 (ZrO ₂ ) _0.88 , that is, , Zrconia oxide powder (c4) (7Yb5ScSZ) in the same manner as in Example 1 except that the zirconia oxide containing 16 mol of Yb and 11 mol of Sc was measured with respect to 100 mol of Zr. Powder) was produced, and a single cell (c4) for SOFC of Comparative Example 4 was produced in the same manner as in Example 1. That is, the zirconia-based oxide powder (c4) of Comparative Example 4 contained a rare earth element other than ytterbium in an amount of more than 8 mol with respect to 100 mol of Zr.

<Comparative example 5>
In the preparation of the zirconia-based oxide powder (1) in Example 1, itterbium chloride (III) hydrate (manufactured by Wako Pure Chemical Industries, Ltd.), scandium chloride (III) hexahydrate (manufactured by Wako Pure Chemical Industries, Ltd.) and chloride. After firing zirconium (IV) (manufactured by Wako Pure Chemical Industries, Ltd.), 10 mol% ittervia 2 mol% scandia-stabilized zirconia (10Yb3ScSZ: (Yb ₂ O ₃ ) _0.10 (Sc ₂ O ₃ ) _0.03 (ZrO ₂ ) _0.87 , that is, , Zrconia oxide powder (c5) in the same manner as in Example 1 except that the zirconia oxide containing 23 mol of Yb and 9.6 mol of Sc was measured with respect to 100 mol of Zr. (10Yb3ScSZ powder) was produced, and further, in the same manner as in Example 1, a single cell (c5) for SOFC of Comparative Example 5 was produced. That is, the zirconia-based oxide powder (c5) of Comparative Example 5 contained a rare earth element other than ytterbium in an amount of more than 8 mol with respect to 100 mol of Zr.

<Comparative Example 6>
In the preparation of the zirconia-based oxide powder (1) in Example 1, itterbium chloride (III) hydrate (manufactured by Wako Pure Chemical Industries, Ltd.), scandium chloride (III) hexahydrate (manufactured by Wako Pure Chemical Industries, Ltd.) and chloride. After firing zirconium (IV) (manufactured by Wako Pure Chemical Industries, Ltd.), 16 mol% ittervia 0.5 mol% scandia-stabilized zirconia (16Yb0.5ScSZ: (Yb ₂ O ₃ ) _0.16 (Sc ₂ O ₃ ) _0.005 (ZrO ₂₎ ) _0.835 , that is, a zirconia oxide containing 38 mol of Yb and 1.2 mol of Sc with respect to 100 mol of Zr), except that the zirconia oxide was measured in the same manner as in Example 1. Powder (c6) (16Yb0.5ScSZ powder) was produced, and further, in the same manner as in Example 1, a single cell (c6) for SOFC of Comparative Example 6 was produced. That is, the zirconia-based oxide powder (c6) of Comparative Example 6 contained ytterbium in an amount of more than 30 mol with respect to 100 mol of Zr.

<Comparative Example 7>
In the preparation of the zirconia oxide powder (1) in Example 1, ytterbium (III) chloride hydrate (manufactured by Wako Pure Chemical Industries, Ltd.), scandium (III) chloride hexahydrate (manufactured by Wako Pure Chemical Industries, Ltd.) and zirconium chloride. (IV) (manufactured by Wako Pure Chemical Industries, Ltd.) is subjected to 5 mol% ytterbium 1 mol% scandia-stabilized zirconia (5Yb1ScSZ: (Yb ₂ O ₃ ) _0.05 (Sc ₂ O ₃ ) _0.01 (ZrO ₂ ) _0.94 , that is, Zirconia oxide powder (c7) (5Yb1ScSZ powder) was produced in the same manner as in Example 1 except that the amount of Yb was 11 mol and Sc was 2.1 mol with respect to 100 mol of Zr. Further, in the same manner as in Example 1, a single cell (c7) for SOFC of Comparative Example 7 was produced.

The measurement method and evaluation method carried out in Examples and Comparative Examples will be described below.

<Measuring method of average particle size of powder>
Sodium pyrophosphate (manufactured by Wako Pure Chemical Industries, Ltd., trade name "sodium pyrophosphate + hydrate") was dissolved in pure water to a concentration of 0.2% by weight to prepare a dispersion medium. The powder was dispersed in this dispersion medium, and the average particle size of the powder was measured using a laser diffraction / scattering type particle size distribution measuring device (manufactured by HORIBA, Ltd., model number LA-920). The average particle size measured here is the median size obtained from the volume-based cumulative particle size distribution, that is, the particle size (D50) at which the volume accumulation corresponds to 50%.

<Evaluation of maximum particle size of aggregates in paste>
The maximum particle size of the agglomerates in the paste is JIS K5600-2-5. It was measured using a grind meter according to the degree of dispersion. Specifically, a paste is dropped in a groove of a grind meter (manufactured by BYK), and a paste layer having a continuously changed thickness is formed in the ironing groove using a scraper. At this time, the thickness of the layer at the place where remarkable spots due to the agglomerates in the paste began to appear is read and used as the maximum particle size of the agglomerates. This measurement was performed three times, and the average value of the three times was calculated to obtain the maximum particle size of the agglomerates in the paste.

<Evaluation of powder composition>
The produced zirconia-based oxide powder and LSCF powder were analyzed by the following methods, and it was confirmed that they were the desired composition.
-For elements larger than 0.5 mol%, XRF (manufactured by BRUKER: S8 TIGER) was used to compress and mold the powder into pellets, and the composition was determined.
-For elements of 0.5 mol% or less, measurement was carried out using ICP (Thermo Scientific: iCAP-6000 series). Specifically, 250 mg of the obtained zirconia oxide powder, 4 g of ammonium sulfate (manufactured by Wako Pure Chemical Industries, Ltd.), and 5 ml of sulfuric acid (for ultrapure water analysis) were placed in a platinum crucible and set at 550 ° C. The solution was dissolved by heating on a hot plate, and the obtained solution was diluted with ultrapure water, and the diluted solution was analyzed to determine the composition.

<Battery performance evaluation test>
The battery performance of each SOFC single cell of each example and comparative example was evaluated by the following method. While supplying 100 mL / min of nitrogen to the fuel electrode of the single cell for SOFC and 100 mL / min of air to the air electrode, the temperature was raised to the measured temperature (750 ° C.) at a rate of 100 ° C./hour. After the temperature was raised, the flow rate of the gas on the outlet side of the fuel electrode and the air electrode was measured with a flow meter, and it was confirmed that there was no leakage. Next, a mixed gas of 6 mL / min of hydrogen and 194 mL / min of nitrogen (3 vol% of water vapor) humidified by a bubbler at a water temperature of 25 ° C. was supplied to the fuel electrode, and 400 mL / min of air was supplied to the air electrode. After reconfirming that electromotive force was generated after 10 minutes or more and there was no leakage, the gas on the fuel electrode side was changed to 194 mL / min of hydrogen humidified by a bubbler having a water temperature of 25 ° C. A battery performance evaluation test based on the current-voltage characteristics was carried out 10 minutes or more after the electromotive force became stable. From the obtained current-voltage characteristics, the output density _{WH2O = 3%} ^{at 0.4 A / cm 2} was determined. Subsequently, the gas on the fuel electrode side was changed by adjusting the bubbler temperature and the hydrogen flow rate so that the hydrogen / steam content was 20/80 vol% and the total flow rate of hydrogen and steam was 200 mL / min. , Supply to the fuel electrode. A battery performance evaluation test based on the current-voltage characteristics was carried out 10 minutes or more after the electromotive force became stable. From the obtained current-voltage characteristics, the output density at ^{0.4 A / cm 2} _{: WH2O = 80%} was determined. _{From WH2O = 3%} and _{WH2O = 80%} obtained above, the output reduction rate ΔW when the water vapor concentration changed from 3% to 80% was calculated by the following formula. The results of the battery performance evaluation tests of each example and each comparative example are shown in Tables 1 and 2.
Output reduction rate: ΔW (%) = [{(W _{H2O = 80%} )-(W _{H2O = 3%} )} ÷ (W _{H2O = 3%} )] × 100

<Evaluation of crystal structure>
(1) Crystal Structure of Zirconia Oxide Powder The crystal structure of the obtained zirconia oxide powder was analyzed by XRD (Spectris Co., Ltd .: X PERT-MPD).
(2) Crystal structure of zirconia oxide in solid electrolyte layer of single cell for SOFC Half cell (a) is used for the crystal structure of zirconia oxide in solid electrolyte layer of single cell for SOFC, and XRD is used for the electrolyte layer. The analysis was performed by (Spectris Co., Ltd .: X PERT-MPD).
(3) Crystal structure of zirconia oxide in the fuel electrode layer of the SOFC single cell For the crystal structure of the zirconia oxide in the fuel electrode of the SOFC single cell, half cell (a) is used, and for the fuel electrode layer, XRD The analysis was performed by (Spectris Co., Ltd .: X PERT-MPD).
Regarding Examples 1 to 12, (1) the crystal structure of the zirconia-based oxide powder, (2) the crystal structure of the zirconia-based oxide in the solid electrolyte layer, and (3) the zirconia-based oxide in the fuel electrode layer. The crystal structures of all of them were the same. Therefore, for Examples 1 to 12, Table 1 summarizes all the crystal structures of (1) to (3) in the column of "crystal phase". The same applies to Comparative Examples 1 to 7 in Table 2. Further, in Examples 13 to 15, the crystal structure of the zirconia-based oxide in the solid electrolyte layer and the crystal structure of the zirconia-based oxide powder used for producing the solid electrolyte layer are the same, and further, the fuel electrode layer. The crystal structure of the zirconia-based oxide in the above was the same as the crystal structure of the zirconia-based oxide powder used for producing the fuel electrode layer thereof. Therefore, for Examples 13 to 15, Table 1 shows the crystal structures of the zirconia-based oxide of the electrolyte layer and the zirconia-based oxide powder used for the preparation thereof, and the zirconia-based oxide of the fuel electrode layer and its preparation. The crystal structures of the zirconia-based oxide powders used in the above are summarized in the column of "Crystal phase".

According to the ionic conductive material of the present invention and a single cell for SOFC, high current-voltage characteristics of SOFC can be realized even in power generation under conditions of high water vapor and carbon dioxide. Therefore, the present invention can contribute to increasing the output of SOFC.

1 Single cell for SOFC 11 Fuel pole 12 Air pole 13 Solid electrolyte layer 14 Barrier layer 111 Fuel pole support substrate 112 Fuel pole layer

Claims (3)

An ionic conductive material containing a zirconia oxide,
The zirconia oxide contains Yb in the range of 6 mol or more and 30 mol or less with respect to 100 mol of Zr, and contains rare earth elements other than ytterbium in the range of 0.005 mol or more and 2.2 mol or less with respect to 100 mol of Zr. Included in
The zirconia-based oxide has a crystal structure having a cubic crystal as a main phase.
Ion conductive material. A solid oxide-type electrochemical cell comprising an air electrode (including an oxygen electrode), a fuel electrode (including a hydrogen electrode), and a solid electrolyte layer arranged between the air electrode and the fuel electrode. There,
The solid electrolyte layer contains a zirconia-based oxide and
The zirconia oxide contains Yb in the range of 6 mol or more and 30 mol or less with respect to 100 mol of Zr, and contains rare earth elements other than ytterbium in the range of 0.005 mol or more and 2.2 mol or less with respect to 100 mol of Zr. Included in
The zirconia-based oxide has a crystal structure having a cubic crystal as a main phase.
Solid oxide electrochemical cell. A solid oxide-type electrochemical cell comprising an air electrode (including an oxygen electrode), a fuel electrode (including a hydrogen electrode), and a solid electrolyte layer arranged between the air electrode and the fuel electrode. There,
The fuel electrode contains a zirconia-based oxide and
The zirconia oxide contains Yb in the range of 6 mol or more and 30 mol or more with respect to 100 mol of Zr, and contains rare earth elements other than ytterbium in the range of 0.005 mol or more and 8 mol or less with respect to 100 mol of Zr. Includes
The zirconia-based oxide has a crystal structure having a cubic crystal as a main phase.
Solid oxide electrochemical cell.

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