Electrolyte sheet for solid oxide fuel cell, method for manufacturing electrolyte sheet for solid oxide fuel cell, and single cell for solid oxide fuel cell

Abstract

The electrolyte sheet for a solid oxide fuel cell of the present invention is composed of a ceramic plate-like body comprising a sintered body of zirconia, and in a cumulative particle size distribution on a number basis of ceramic particles, the particle size D 90 at a cumulative probability of 90% is 2.5 μm or more than the particle size D 10 at a cumulative probability of 10%.

Description

TECHNICAL FIELD

[0001] The present application relates to an electrolyte sheet for solid oxide fuel cell, a method for manufacturing an electrolyte sheet for solid oxide fuel cell, and a single cell for solid oxide fuel cell. BACKGROUND

[0002] A solid oxide fuel cell (SOFC) is a device that extracts electric power by the reaction of a fuel electrode: H2+ O 2－ → H2O + 2e － , an air electrode: (1 / 2) O2+ 2e － → O 2－ A solid oxide fuel cell can be used as a stacked structure by overlapping a plurality of single cells for solid oxide fuel cell, which is formed by providing a fuel electrode and an air electrode on an electrolyte sheet for solid oxide fuel cell composed of a ceramic plate-like body.

[0003] As a method for manufacturing an electrolyte sheet for solid oxide fuel cell, a method for manufacturing a scandia-stabilized zirconia sheet is disclosed in Patent Literature 1, which includes: a step of pulverizing a sintered body of scandia-stabilized zirconia to obtain a scandia-stabilized zirconia sintered powder having an average particle diameter De exceeding 0.3 μm and 1.5 μm or less as measured by a transmission electron microscope, an average particle diameter Dr exceeding 0.3 μm and 3.0 μm or less as measured by a laser scattering method, and Dr / De being 1.0 to 2.5; a step of preparing a slurry containing the scandia-stabilized zirconia sintered powder and a zirconia unsintered powder, and the proportion of the scandia-stabilized zirconia sintered powder in the slurry with respect to the total of the scandia-stabilized zirconia sintered powder and the zirconia unsintered powder being 2 mass% to 40 mass%; a step of molding the slurry into a sheet shape; and a step of sintering the obtained molded body.

[0004] PRIOR ART DOCUMENTS

[0005] PATENT LITERATURE

[0006] Patent Literature 1: Japanese Patent Application Laid-Open No. 2011-105589 (Patent No. 4796656) SUMMARY

[0007] However, in the electrolyte sheet for solid oxide fuel cell composed of the scandia-stabilized zirconia sheet manufactured by the manufacturing method described in Patent Literature 1, there is a problem that the strength decreases when thinning is intended in order to improve the power generation efficiency of the solid oxide fuel cell.

[0008] The present application has been achieved in order to solve the above problems, and has an object to provide a solid oxide fuel cell electrolyte sheet with high strength. In addition, the present application has an object to provide a manufacturing method of a solid oxide fuel cell electrolyte sheet with high strength. Furthermore, the present application has an object to provide a solid oxide fuel cell single cell having the above solid oxide fuel cell electrolyte sheet.

[0009] The solid oxide fuel cell electrolyte sheet of the present application is characterized by being composed of a ceramic plate-like body including a sintered body of zirconia, in a cumulative particle size distribution on a number basis of ceramic particles, a particle size D 90 is 2.5 μm or more. 10

[0010] The manufacturing method of a solid oxide fuel cell electrolyte sheet of the present application is characterized by comprising: a step of preparing a zirconia sintered powder having a particle size D 50 of 3 μm or less and a particle size D 99 of 6 μm or more; a step of mixing the above zirconia sintered powder and a zirconia unsintered powder so that the weight ratio of the above zirconia sintered powder with respect to the total weight of the above zirconia sintered powder and the above zirconia unsintered powder is 5 to 50% by weight, thereby preparing a ceramic slurry; a step of producing a ceramic green sheet by molding the above ceramic slurry; and a step of producing a ceramic plate-like body by sintering an unsintered plate-like body including the above ceramic green sheet.

[0011] The solid oxide fuel cell single cell of the present application is characterized by comprising: a fuel electrode, an air electrode, and the solid oxide fuel cell electrolyte sheet of the present application disposed between the above fuel electrode and the above air electrode.

[0012] According to the present application, a solid oxide fuel cell electrolyte sheet with high strength can be provided. In addition, according to the present application, a manufacturing method of a solid oxide fuel cell electrolyte sheet with high strength can be provided. Furthermore, according to the present application, a solid oxide fuel cell single cell having the above solid oxide fuel cell electrolyte sheet can be provided. BRIEF DESCRIPTION OF DRAWINGS

[0013] Figure 1 is a plan view schematically showing one example of the solid oxide fuel cell electrolyte sheet of the present application.

[0014] Figure 2 is a plan view schematically showing one example of the solid oxide fuel cell electrolyte sheet of the present application. Figure 1 ​A cross-sectional view of a portion corresponding to the line segment Al-A2 in FIG. 1.

[0015] Figure 3 A plan view showing a process of producing a ceramic green sheet in one example of a method of manufacturing an electrolyte sheet for a solid oxide fuel cell according to the present application.

[0016] Figure 4 A plan view showing a process of producing a ceramic green sheet in one example of a method of manufacturing an electrolyte sheet for a solid oxide fuel cell according to the present application.

[0017] Figure 5 A plan view showing a process of producing a ceramic green sheet in one example of a method of manufacturing an electrolyte sheet for a solid oxide fuel cell according to the present application.

[0018] Figure 6 A cross-sectional view showing a method of producing an unsintered sheet-shaped body in a process of producing a ceramic sheet-shaped body in one example of a method of manufacturing an electrolyte sheet for a solid oxide fuel cell according to the present application.

[0019] Figure 7 A cross-sectional view showing a method of calcining an unsintered sheet-shaped body in a process of producing a ceramic sheet-shaped body in one example of a method of manufacturing an electrolyte sheet for a solid oxide fuel cell according to the present application.

[0020] Figure 8 A cross-sectional view showing one example of a single cell for a solid oxide fuel cell according to the present application.

[0021] Figure 9 A graph showing a probability distribution of particle diameters of ceramic particles of the electrolyte sheet of Example 1.

[0022] Figure 10 A graph showing a cumulative particle size distribution of ceramic particles of the electrolyte sheet of Example 1 on a number basis. DETAILED DESCRIPTION

[0023] Hereinafter, an electrolyte sheet for a solid oxide fuel cell according to the present application (hereinafter also referred to as an electrolyte sheet), a method of manufacturing an electrolyte sheet for a solid oxide fuel cell according to the present application (hereinafter also referred to as a method of manufacturing an electrolyte sheet), and a single cell for a solid oxide fuel cell according to the present application (hereinafter also referred to as a single cell) will be described. Note that the present application is not limited to the following configurations, and can be appropriately changed within a scope that does not depart from the gist of the present application. In addition, a scheme obtained by combining a plurality of each of the preferred configurations described below also belongs to the present application.

[0024] The drawings shown below are schematic views, and the scale of the dimensions, the aspect ratio, and the like can sometimes differ from those of actual products.

[0025] [Electrolyte sheet for solid oxide fuel cell]

[0026] An example of the electrolyte sheet for a solid oxide fuel cell of the present application will be described below.

[0027] Figure 1 is a plan view showing an example of the electrolyte sheet for a solid oxide fuel cell of the present application. Figure 2 is a cross-sectional view showing a portion corresponding to the line segment Al-A2 in Figure 1

[0028] Figure 1 The electrolyte sheet 10 for a solid oxide fuel cell shown in Figure 2 The electrolyte sheet 10 for a solid oxide fuel cell shown in

[0029] As the sintered body of zirconia, for example, a sintered body of zirconia stabilized by an oxide of a rare earth element such as scandium, yttrium, or the like can be given, and more specifically, a sintered body of zirconia stabilized by scandia, a sintered body of zirconia stabilized by yttria, or the like can be given.

[0030] The sintered body of zirconia is preferably a sintered body of zirconia stabilized by scandia. By the electrolyte sheet 10 being composed of a ceramic plate-like body including a sintered body of zirconia stabilized by scandia, the electrical conductivity of the electrolyte sheet 10 is improved. In this case, by the electrolyte sheet 10 being assembled into a solid oxide fuel cell, the power generation efficiency of the solid oxide fuel cell is improved.

[0031] The sintered body of zirconia is preferably a sintered body of cubic zirconia. By the electrolyte sheet 10 being composed of a ceramic plate-like body including a sintered body of cubic zirconia, the electrical conductivity of the electrolyte sheet 10 is improved. In this case, by the electrolyte sheet 10 being assembled into a solid oxide fuel cell, the power generation efficiency of the solid oxide fuel cell is improved.

[0032] As the sintered body of cubic zirconia, for example, a sintered body of cubic zirconia stabilized by an oxide of a rare earth element such as scandium, yttrium, or the like can be given, and more specifically, a sintered body of cubic zirconia stabilized by scandia, a sintered body of cubic zirconia stabilized by yttria, or the like can be given.

[0033] ​The sintered body of cubic zirconia is preferably a sintered body of cubic zirconia stabilized by scandia. By the electrolyte sheet 10 being composed of a ceramic plate-like body including a sintered body of cubic zirconia stabilized by scandia, the electric conductivity of the electrolyte sheet 10 is significantly improved. In this case, by the electrolyte sheet 10 being assembled into a solid oxide fuel cell, the power generation efficiency of the solid oxide fuel cell is significantly improved.

[0034] The electrolyte sheet 10 is, for example, a square as shown in FIG. 1 when viewed from the thickness direction. Figure 1

[0035] The electrolyte sheet 10 is, for example, a square as shown in FIG. 1 when viewed from the thickness direction.

[0036] Although not shown, it is preferable that a through hole that penetrates through in the thickness direction be provided in the electrolyte sheet 10. Such a through hole functions as a flow path of a gas in a solid oxide fuel cell.

[0037] The number of the through holes can be only one or two or more.

[0038] The through hole can be circular or a shape other than this when viewed from the thickness direction.

[0039] The position of the through hole is not particularly limited.

[0040] The size of the electrolyte sheet 10 is, for example, 50 mm x 50 mm, 100 mm x 100 mm, 110 mm x 110 mm, 120 mm x 120 mm, 200 mm x 200 mm, or the like when viewed from the thickness direction.

[0041] The thickness of the electrolyte sheet 10 (ceramic plate-like body) is preferably 200 μm or less, more preferably 130 μm or less. In addition, the thickness of the electrolyte sheet 10 is preferably 30 μm or more, more preferably 50 μm or more.

[0042] The thickness of the electrolyte sheet 10 can be determined as follows. First, the thickness of any 9 portions of a region that is 5 mm or more inward from the outer edge of the electrolyte sheet 10 is measured using a U-shaped steel plate micrometer "PMU-MX" manufactured by Mitutoyo Corporation. Then, the average value calculated from the measured values of the thickness of the 9 portions is determined as the thickness of the electrolyte sheet 10.

[0043] ​Although not shown, it is preferable that recesses be scattered on at least one side main surface of the electrolyte sheet 10. By scattering the recesses on at least one side main surface of the electrolyte sheet 10, the contact area of the electrode with the gas becomes large when the electrolyte sheet 10 is assembled to the solid oxide fuel cell, and thus the power generation efficiency of the solid oxide fuel cell is improved. The recesses can be scattered on only one side main surface of the electrolyte sheet 10, but it is particularly preferable that the recesses be scattered on both one side main surface and the other side main surface.

[0044] In the electrolyte sheet 10, in a cumulative particle size distribution on a number basis of the ceramic particles, the particle diameter D 90 at which the cumulative probability is 10% is 2.5 μm or more. 10

[0045] When the electrolyte sheet is assembled to the solid oxide fuel cell, the fuel electrode slurry and the air electrode slurry are applied to the electrolyte sheet, or a single cell provided with a fuel electrode and an air electrode is laminated together with a separator on the electrolyte sheet, and thus a load is applied to the electrolyte sheet. Therefore, the electrolyte sheet with low strength is easily broken due to the load applied as described above. When the electrolyte sheet is broken, a crack in the electrolyte sheet generally propagates through the particles of the ceramic particles.

[0046] On the contrary, in the electrolyte sheet 10, by the cumulative particle size distribution on a number basis of the ceramic particles satisfying the above condition, the probability distribution of the particle diameter of the ceramic particles becomes wide, and there are ceramic particles with large particle diameters. Therefore, in the electrolyte sheet 10, the ceramic particles with large particle diameters suppress the propagation of the crack, and contribute to the suppression of the decrease in strength. As a result, the electrolyte sheet 10 with high strength is achieved. Such an electrolyte sheet 10 with high strength is not easily broken even when a load as described above is applied when assembled to the solid oxide fuel cell.

[0047] ​The cumulative particle size distribution based on the number of ceramic particles in the electrolyte sheet was determined as follows. First, for any part of the electrolyte sheet (e.g., the central part), an image of an area containing more than 100 ceramic particles with a size of 30μm × 30μm was captured using a Hitachi TM3000 desktop microscope at 3000x magnification. Next, the obtained image was analyzed using the WinROOF2018 grain boundary extraction module image analysis and measurement system manufactured by Mitani Corporation, and the particle size of the more than 100 ceramic particles was determined as the equivalent circle diameter. Then, for the particle size measurement results of each ceramic particle, the cumulative probability of being below the particle size of that ceramic particle was calculated by specifying "TRUE" in the "NORMDIST" function (or "NORM.DIST" function) of the Microsoft Excel spreadsheet software. Then, based on the obtained cumulative probability, the cumulative particle size distribution based on the number of ceramic particles was determined.

[0048] In the cumulative particle size distribution based on the number of ceramic particles determined as described above, the particle size D with a cumulative probability of 90% is determined. 90 And particle size D with a cumulative probability of 10% 10 At that time, in electrolyte sheet 10, the particle size D 90 With particle size D 10 The difference is greater than 2.5 μm. It should be noted that in electrolyte sheet 10, in the cumulative particle size distribution based on the number of ceramic particles, the particle size D... 90 With particle size D 10 The difference is preferably greater than 2.6 μm.

[0049] In electrolyte sheet 10, in the cumulative particle size distribution based on the number of ceramic particles, the particle size D 90 With particle size D 10 The difference is preferably 3.5 μm or less, more preferably 3.1 μm or less.

[0050] In electrolyte sheet 10, the particle size D in the cumulative particle size distribution based on the number of ceramic particles is... 90 Preferably, the micrometer is 3μm to 4μm, and more preferably 3.2μm to 3.8μm.

[0051] In electrolyte sheet 10, the particle size D in the cumulative particle size distribution based on the number of ceramic particles is... 10 Preferably, the micrometer is 0.5 μm to 1 μm, and more preferably 0.7 μm to 0.9 μm.

[0052] Note that, for the measurement results of the particle diameters of the ceramic particles described above, the probability density of the particle diameters of the ceramic particles can be calculated by using the function "NORMDIST" (or the function "NORM.DIST") of the table calculation software "Microsoft Excel" manufactured by Microsoft Corporation, designating "FALSE" in the function form. Then, the probability distribution of the particle diameters of the ceramic particles can be determined based on the obtained probability density. For the electrolyte sheet 10, when the probability distribution of the particle diameters of the ceramic particles is determined as described above, it is known that the probability distribution is wide and that there are ceramic particles having large particle diameters.

[0053] [Method for manufacturing electrolyte sheet for solid oxide fuel cell]

[0054] One example of the method for manufacturing an electrolyte sheet for a solid oxide fuel cell according to the present application will be described below.

[0055] <Process of preparing zirconia sintered powder>

[0056] In the cumulative particle size distribution on a volume basis, a zirconia sintered powder having a particle diameter D 50 (also referred to as a median particle diameter) of 3 μm or less and a particle diameter D 99 having a cumulative probability of 99% of 6 μm or more is prepared.

[0057] As described above, when the electrolyte sheet is fractured, a crack in the electrolyte sheet generally propagates through the grains of the ceramic particles. Therefore, in the electrolyte sheet, if the probability distribution of the particle diameters of the ceramic particles is wide and there are ceramic particles having large particle diameters, the propagation of the crack is easily suppressed.

[0058] In the present manufacturing method, by using a zirconia sintered powder having a particle diameter D 50 of 3 μm or less and a particle diameter D 99 of 6 μm or more in the cumulative particle size distribution on a volume basis, the probability distribution of the particle diameters of the ceramic particles is made wide and there are ceramic particles having large particle diameters in the electrolyte sheet obtained through the subsequent processes.

[0059] In the present manufacturing method, as described later, a ceramic slurry including a mixture of a zirconia sintered powder and a zirconia unsintered powder is molded and then sintered, thereby manufacturing an electrolyte sheet. Therefore, in order to achieve sinterability close to that of the zirconia unsintered powder, it is important to use a zirconia sintered powder having a particle diameter D 50 of 3 μm or less in the cumulative particle size distribution on a volume basis. Furthermore, for the zirconia sintered powder, by making the particle diameter D 99Assuming a particle size of 6 μm or larger, coarse particles with a diameter of 6 μm or larger become the nuclei for particle growth during the sintering of the ceramic slurry, promoting overall particle growth. As a result, as described later, electrolyte sheets with a wide probability distribution of ceramic particle size and the presence of large-sized ceramic particles are obtained.

[0060] The cumulative particle size distribution of the zirconia sintered powder based on volume is determined as follows. First, the particle size distribution of the zirconia sintered powder is measured using a laser scattering method, such as a laser diffraction particle size distribution measuring device. At this time, the particle size of the zirconia sintered powder is measured as the equivalent circle diameter. Then, the cumulative particle size distribution of the zirconia sintered powder based on volume is determined by transforming the obtained particle size distribution of the zirconia sintered powder into a particle size distribution expressed as cumulative probability.

[0061] In the cumulative particle size distribution of the zirconia sintered powder based on the volume as determined above, the particle size D with a cumulative probability of 50% is determined. 50 And particle size D with a cumulative probability of 99% 99 At that time, the particle size D of the zirconia sintered powder used in this manufacturing method is... 50 The particle size is less than 3 μm and the particle size D 99 It is above 6μm.

[0062] For zirconia sintered powder, the particle size D in the volume-based cumulative particle size distribution 50 The size is less than 3μm, preferably less than 2.5μm.

[0063] For zirconia sintered powder, the particle size D in the volume-based cumulative particle size distribution 50 Preferably, the micrometer is 0.5 μm or more, and more preferably 1.5 μm or more.

[0064] For zirconia sintered powder, the particle size D in the volume-based cumulative particle size distribution 99 The size is 6μm or larger, preferably 6.1μm or larger.

[0065] For zirconia sintered powder, the particle size D in the volume-based cumulative particle size distribution 99 Preferably, the micrometer is 8.5 μm or less, and more preferably 7.9 μm or less.

[0066] In this process, it is preferable to prepare zirconia sintered powder by crushing the sintered zirconia body.

[0067] As the sintered body of zirconia, for example, a sintered body obtained by sintering zirconia unsintered powder is used as a raw material of the zirconia sintered powder when the zirconia sintered powder is prepared. As such a sintered body of zirconia, an electrolyte sheet composed of a sintered body of zirconia can be used, and from the viewpoint of recycling, an electrolyte sheet, an electrolyte sheet assembled into a solid oxide fuel cell, or the like, which has generated a defect such as warping or breakage, is preferably used. In the case where the electrolyte sheet assembled into the solid oxide fuel cell is used, the electrolyte sheet can be taken out, for example, by removing the fuel electrode and the air electrode from a used single cell, a single cell that has generated a defect, or the like.

[0068] As the sintered body of zirconia, for example, a sintered body of zirconia stabilized by an oxide of a rare earth element such as scandium or yttrium, and more specifically, a sintered body of zirconia stabilized by scandia, a sintered body of zirconia stabilized by yttria, or the like is used.

[0069] As the sintered body of zirconia, a sintered body of zirconia stabilized by scandia is preferably used. That is, as the zirconia sintered powder, a zirconia sintered powder stabilized by scandia is preferably used. By using the zirconia sintered powder stabilized by scandia, an electrolyte sheet having a high electrical conductivity can be manufactured. In this case, by assembling the manufactured electrolyte sheet into a solid oxide fuel cell, the power generation efficiency of the solid oxide fuel cell can be improved.

[0070] As the sintered body of zirconia, a sintered body of cubic zirconia is preferably used. That is, as the zirconia sintered powder, a zirconia sintered powder of cubic zirconia is preferably used. By using the zirconia sintered powder of cubic zirconia, an electrolyte sheet having a high electrical conductivity can be manufactured. In this case, by assembling the manufactured electrolyte sheet into a solid oxide fuel cell, the power generation efficiency of the solid oxide fuel cell can be improved.

[0071] As the sintered body of cubic zirconia, for example, a sintered body of cubic zirconia stabilized by an oxide of a rare earth element such as scandium or yttrium, and more specifically, a sintered body of cubic zirconia stabilized by scandia, a sintered body of cubic zirconia stabilized by yttria, or the like is used.

[0072] As the sintered body of cubic zirconia, a sintered body of cubic zirconia stabilized by scandia is preferably used. That is, as the zirconia sintered powder, a zirconia sintered powder of cubic zirconia stabilized by scandia is preferably used. By using the zirconia sintered powder of cubic zirconia stabilized by scandia, an electrolyte sheet having a significantly high electrical conductivity can be manufactured. In this case, by assembling the manufactured electrolyte sheet into a solid oxide fuel cell, the power generation efficiency of the solid oxide fuel cell can be significantly improved.

[0073] When the sintered body of zirconia is pulverized, dry pulverization is preferably performed. According to the dry pulverization, the sintered body of zirconia can be pulverized with strong impact, and thus the pulverization efficiency can be easily improved.

[0074] As the dry pulverizer for performing the dry pulverization, for example, a jet mill, a vibration mill, a planetary mill, a dry ball mill, a fine mill, or the like is used.

[0075] As the pulverizing medium for the dry pulverizer, for example, a zirconia-made ball stone or the like is used.

[0076] When the sintered body of zirconia is dry-pulverized, by adjusting the rotational speed of the classification rotor of the dry pulverizer, the pulverization time, or the like, the sintered powder of zirconia having the cumulative particle size distribution based on the volume can be obtained.

[0077] When the sintered body of zirconia is pulverized, instead of the dry pulverization, wet pulverization can be performed, or the dry pulverization and the wet pulverization can be combined, but from the viewpoint of the pulverization efficiency, it is preferable that only the dry pulverization is performed.

[0078] <Preparation of ceramic slurry>

[0079] The sintered powder of zirconia and the unsintered powder of zirconia are mixed so that the weight ratio of the sintered powder of zirconia with respect to the total weight of the sintered powder of zirconia and the unsintered powder of zirconia is 5% by weight to 50% by weight, and thus the ceramic slurry is prepared.

[0080] In this process, the sintered powder of zirconia and the unsintered powder of zirconia are preferably mixed so that the weight ratio of the sintered powder of zirconia with respect to the total weight of the sintered powder of zirconia and the unsintered powder of zirconia is 5% by weight to 30% by weight.

[0081] When the ceramic slurry is prepared, if the weight ratio of the sintered powder of zirconia with respect to the total weight of the sintered powder of zirconia and the unsintered powder of zirconia is set to be less than 5% by weight, the weight ratio of the coarse particles of the sintered powder of zirconia becomes too small, and thus the growth of the particles as a whole cannot be promoted when the ceramic slurry is sintered.

[0082] When the ceramic slurry is prepared, if the weight ratio of the sintered powder of zirconia with respect to the total weight of the sintered powder of zirconia and the unsintered powder of zirconia is set to be more than 50% by weight, the weight ratio of the coarse particles of the sintered powder of zirconia becomes too large, and thus the sinterability of the ceramic slurry is reduced. As a result, the strength of the electrolyte sheet obtained thereafter is reduced.

[0083] The unsintered powder of zirconia preferably has a particle size D50 at which the cumulative probability is 50% in the cumulative particle size distribution based on the volume of 0.1 μm to 0.3 μm, and a particle size D99 at which the cumulative probability is 99% of 1 μm to 3 μm. 50 0.1 μm to 0.3 μm, and a particle size D99 at which the cumulative probability is 99% of 1 μm to 3 μm.99 is 1.5 μm to 2.5 μm.

[0084] As the zirconia un-sintered powder, for example, a zirconia un-sintered powder stabilized by an oxide of scandium, yttrium or the like of rare earth elements is used, and more specifically, a zirconia un-sintered powder stabilized by an oxide of scandium, a zirconia un-sintered powder stabilized by an oxide of yttrium or the like is used.

[0085] As the zirconia un-sintered powder, a zirconia un-sintered powder stabilized by an oxide of scandium is preferably used. By using a zirconia un-sintered powder stabilized by an oxide of scandium, an electrolyte sheet having a high electric conductivity can be manufactured. In this case, by assembling the manufactured electrolyte sheet into a solid oxide fuel cell, the power generation efficiency of the solid oxide fuel cell can be improved.

[0086] As the zirconia un-sintered powder, a cubic crystal system zirconia un-sintered powder is preferably used. By using a cubic crystal system zirconia un-sintered powder, an electrolyte sheet having a high electric conductivity can be manufactured. In this case, by assembling the manufactured electrolyte sheet into a solid oxide fuel cell, the power generation efficiency of the solid oxide fuel cell can be improved.

[0087] As the cubic crystal system zirconia un-sintered powder, for example, a cubic crystal system zirconia un-sintered powder stabilized by an oxide of scandium, yttrium or the like of rare earth elements is used, and more specifically, a cubic crystal system zirconia un-sintered powder stabilized by an oxide of scandium, a cubic crystal system zirconia un-sintered powder stabilized by an oxide of yttrium or the like is used.

[0088] As the cubic crystal system zirconia un-sintered powder, a cubic crystal system zirconia un-sintered powder stabilized by an oxide of scandium is preferably used. By using a cubic crystal system zirconia un-sintered powder stabilized by an oxide of scandium, an electrolyte sheet having a significantly high electric conductivity can be manufactured. In this case, by assembling the manufactured electrolyte sheet into a solid oxide fuel cell, the power generation efficiency of the solid oxide fuel cell can be significantly improved.

[0089] In the preparation of the ceramic slurry, in addition to the zirconia sintered powder and the zirconia un-sintered powder, a binder, a dispersant, an organic solvent or the like can be appropriately blended.

[0090] <Manufacturing Process of Ceramic Green Sheet>

[0091] Figure 3 Figure 4 and Figure 5 is a plan view schematically showing a manufacturing process of a ceramic green sheet in one example of a method of manufacturing an electrolyte sheet for a solid oxide fuel cell according to the present application.

[0092] First, a ceramic slurry is formed on one main surface of a support film to manufacture a ceramic green sheet as shown in Figure 3 ​The ceramic raw material shown is 1 t.

[0093] As a method for forming ceramic slurry, belt forming is preferred, and scraper forming or calendering is even more preferred. Figure 3 In this context, the casting direction when ceramic slurry is formed using the strip forming method is represented by X, and the direction perpendicular to the casting direction is represented by Y.

[0094] Moreover, such as Figure 4 As shown, 1 ton of ceramic green tape is punched into a specified size using a known method, and the carrier membrane is peeled off, thereby producing a product as shown. Figure 5 The ceramic green sheet shown is 1g. There are no restrictions on the order of punching and peeling off the carrier film for 1t of ceramic green tape.

[0095] <Processes for making ceramic slabs>

[0096] First, an unsintered plate containing ceramic green sheets is made.

[0097] Figure 6 This is a cross-sectional schematic diagram illustrating an example of a method for manufacturing an electrolyte sheet for a solid oxide fuel cell according to the present invention, showing the method of manufacturing an unsintered plate in the process of manufacturing a ceramic plate.

[0098] like Figure 6 As shown, an unsintered plate-like body 1s is produced by stacking and pressing two ceramic green sheets 1g together. Therefore, it can be said that the unsintered plate-like body 1s contains 1g of ceramic green sheets.

[0099] The number of ceramic green sheets (1g) produced in 1 second for unsintered plate-like structures can be as follows: Figure 6 The image shows two sheets, but more than three sheets can also be used. These multiple ceramic green sheets 1g can be pressed together or simply stacked without pressing. When producing an unsintered plate 1s from multiple ceramic green sheets 1g, the thickness of the resulting ceramic plate can be appropriately and easily controlled.

[0100] It should be noted that an unsintered plate-like body of 1 second can also be made from a single 1g ceramic green sheet. In this case, [details omitted]. Figure 6 The process shown.

[0101] Next, although not shown, recesses scattered on one side of the main surface of the unsintered plate 1s can also be formed. For example, recesses scattered on one side of the main surface of the unsintered plate 1s can be formed by pressing a mold with protrusions scattered on its surface.

[0102] The protrusions scattered on the surface of the mold can be arranged regularly or irregularly.

[0103] Alternatively, recesses can be formed on one side and the other side of the unsintered plate-like body 1s.

[0104] Note that the recesses can not be formed in the one side main face and the other side main face of the unsintered plate-like body Is.

[0105] Next, although not shown, a through-hole that penetrates the unsintered plate-like body Is in the thickness direction can be formed.

[0106] When the unsintered plate-like body Is is formed with the through-hole, a drill is preferably used. In this case, the through-hole that penetrates the unsintered plate-like body Is in the thickness direction is formed by the drill from the one side main face toward the other side main face of the unsintered plate-like body Is. The machining conditions using the drill are not particularly limited.

[0107] The through-hole can be formed only one, or two or more can be formed.

[0108] Note that the through-hole can not be formed.

[0109] When the unsintered plate-like body Is is formed with the recesses and the through-hole, the order of formation of the recesses and the through-hole is not limited.

[0110] Next, the ceramic plate-like body is produced by sintering the unsintered plate-like body Is.

[0111] Figure 7 is a cross-sectional schematic view showing a manner of calcining the unsintered plate-like body in the process of producing the ceramic plate-like body in one example of a method of producing an electrolyte sheet for a solid oxide fuel cell according to the present application.

[0112] The unsintered plate-like body Is is sintered by calcining the unsintered plate-like body Is, as shown in Figure 7 to produce the ceramic plate-like body 10p. The ceramic plate-like body 10p includes a sintered body of zirconia.

[0113] When the unsintered plate-like body Is is calcined, a debinding treatment and a sintering treatment are preferably performed.

[0114] When the recesses are formed in the one side main face of the unsintered plate-like body Is, the recesses are formed in the one side main face of the ceramic plate-like body 10p in a scattered manner, as shown in Figure 7

[0115] In addition, when the recesses are formed in the one side main face and the other side main face of the unsintered plate-like body Is, the recesses are formed in the one side main face and the other side main face of the ceramic plate-like body 10p in a scattered manner.

[0116] When the ceramic plate-like body 10p is formed with the recesses, the recesses can be regularly arranged, or can not be regularly arranged. ​

[0117] Note that a ceramic plate-shaped body in which no recesses are dispersed on both the one side main surface and the other side main surface can also be produced.

[0118] Further, in a case where the through hole is formed in the unsintered plate-shaped body Is, the through hole that penetrates in the thickness direction is provided in the ceramic plate-shaped body 10p.

[0119] By the above, the electrolyte sheet composed of the ceramic plate-shaped body 10p is produced.

[0120] In the present production method, as described above, in the process of preparing the zirconia sintered powder, a zirconia sintered powder having a particle size D 50 of 3 μm or less and a particle size D 99 of 6 μm or more is prepared, and further, in the process of preparing the ceramic slurry, the weight ratio of the zirconia sintered powder with respect to the total weight of the zirconia sintered powder and the zirconia unsintered powder is set to 50% by weight or less. Therefore, in the ceramic plate-shaped body 10p produced using such a ceramic slurry, the probability distribution of the particle size of the ceramic particles is wide, and there are ceramic particles having a large particle size, and the strength is improved. More specifically, in the ceramic plate-shaped body 10p, in the cumulative particle size distribution on a number basis of the ceramic particles, the difference between the particle size D 90 and the particle size D 10 is 2.5 μm or more, and the strength is improved. That is, according to the present production method, the electrolyte sheet for a solid oxide fuel cell of the present application composed of the ceramic plate-shaped body 10p can be produced.

[0121] [Single cell for a solid oxide fuel cell]

[0122] One example of a single cell for a solid oxide fuel cell of the present application will be described below.

[0123] Figure 8 is a cross-sectional schematic view showing one example of a single cell for a solid oxide fuel cell of the present application.

[0124] As shown in Figure 8 , the single cell for a solid oxide fuel cell 100 has a fuel electrode 110, an air electrode 120, and an electrolyte sheet 130. The electrolyte sheet 130 is provided between the fuel electrode 110 and the air electrode 120.

[0125] As the fuel electrode 110, a publicly known fuel electrode for a solid oxide fuel cell is used.

[0126] As the air electrode 120, a publicly known air electrode for a solid oxide fuel cell is used.

[0127] As the electrolyte sheet 130, the electrolyte sheet for a solid oxide fuel cell of the present application (for example, the electrolyte sheet 10p) is used.Figure 1 and Figure 2 electrolyte sheet 10). Therefore, when the single cell 100 is assembled into a solid oxide fuel cell, the power generation efficiency of the solid oxide fuel cell is improved.

[0128] [Method for manufacturing single cell for solid oxide fuel cell]

[0129] One example of the method for manufacturing a single cell for a solid oxide fuel cell of the present application will be described below.

[0130] First, a slurry for a fuel electrode is prepared by appropriately adding a binder, a dispersant, a solvent, and the like to a powder of a material for a fuel electrode. In addition, a slurry for an air electrode is prepared by appropriately adding a binder, a dispersant, a solvent, and the like to a powder of a material for an air electrode.

[0131] As the material for a fuel electrode, a publicly known material for a fuel electrode of a solid oxide fuel cell is used.

[0132] As the material for an air electrode, a publicly known material for an air electrode of a solid oxide fuel cell is used.

[0133] As the binder, the dispersant, the solvent, and the like contained in the slurry for a fuel electrode and the slurry for an air electrode, a publicly known binder, dispersant, solvent, and the like in a method for forming a fuel electrode and an air electrode of a solid oxide fuel cell are used.

[0134] Next, the slurry for a fuel electrode is applied to one main surface of the electrolyte sheet, and the slurry for an air electrode is applied to the other main surface of the electrolyte sheet, each at a prescribed thickness. Then, by drying these applied films, a green layer for a fuel electrode and a green layer for an air electrode are formed.

[0135] Then, by calcining the green layer for a fuel electrode and the green layer for an air electrode, a fuel electrode and an air electrode are formed. The calcination conditions such as the calcination temperature are appropriately determined in accordance with the kind of the material for the fuel electrode and the air electrode, and the like.

[0136] Example

[0137] Examples further specifically disclosing the electrolyte sheet for a solid oxide fuel cell of the present application and the method for manufacturing an electrolyte sheet for a solid oxide fuel cell of the present application will be shown below. It should be noted that the present application is not limited to these examples.

[0138] [Example 1]

[0139] The electrolyte sheet of Example 1 was manufactured by the following method.

[0140] <Preparation of zirconia sintered powder>

[0141] By dry pulverizing the sintered body of zirconia, a zirconia sintered powder having a particle size D 50 of 1.5 μm and a particle size D 99 of 6.1 μm was obtained.

[0142] As the sintered body of zirconia, a sintered body of zirconia stabilized by scandium oxide obtained by sintering zirconia unstabilized powder stabilized by scandium oxide was used. That is, as the zirconia sintered powder, a zirconia sintered powder stabilized by scandium oxide was obtained.

[0143] As the pulverizing medium for the dry pulverizer, a ball stone made of zirconia having a diameter of 1 mm to 10 mm was used.

[0144] The rotational speed of the classification rotor of the dry pulverizer was set to 4,000 rpm or more.

[0145] <Process for preparing ceramic slurry>

[0146] First, the zirconia sintered powder, the zirconia unstabilized powder, the binder, the dispersant, and the organic solvent were mixed in a prescribed ratio. At this time, the zirconia sintered powder and the zirconia unstabilized powder were mixed so that the weight ratio of the zirconia sintered powder with respect to the total weight of the zirconia sintered powder and the zirconia unstabilized powder was 10% by weight. Then, the obtained mixture was stirred at 1,000 rpm for 3 hours together with a medium composed of partially stabilized zirconia to prepare a ceramic slurry.

[0147] As the zirconia unstabilized powder, a zirconia unstabilized powder stabilized by scandium oxide was used. The zirconia unstabilized powder had a particle size D 50 of 0.2 μm and a particle size D 99 of 1.8 μm in the cumulative particle size distribution on a volume basis.

[0148] As the organic solvent, a mixed solvent of toluene and ethanol (weight ratio 7:3) was used.

[0149] <Process for making ceramic green sheet>

[0150] First, the ceramic slurry was tape-formed on one main surface of a support film composed of polyethylene terephthalate by a known method, whereby a ceramic green tape was made.

[0151] Then, the ceramic green tape was punched to a prescribed size and the support film was peeled off by a known method, whereby a ceramic green sheet was made.

[0152] <Process for making ceramic plate-like body>

[0153] First, an unstabilized plate-like body was made by laminating and pressure-bonding two ceramic green sheets.

[0154] Next, a recess portion is formed in the one side main surface of the unsintered plate-like body by pressing a mold having protrusions dispersed on the surface.

[0155] Next, a through-hole is formed in the unsintered plate-like body by using a drill bit.

[0156] For the machining conditions using the drill bit, the advancing speed is set to 0.04 mm / revolution, and the rotation speed is set to 2000 revolutions / minute.

[0157] Next, the unsintered plate-like body is subjected to a debinding treatment at 400°C for a prescribed time using a calcination furnace. Then, the unsintered plate-like body after the debinding treatment is subjected to a sintering treatment at 1400°C for 5 hours using a calcination furnace.

[0158] By thus calcining the unsintered plate-like body, the unsintered plate-like body is sintered, and a ceramic plate-like body is produced. The thickness of the ceramic plate-like body is 120 μm.

[0159] By the above, the electrolyte sheet (ceramic plate-like body) of Example 1 is produced.

[0160] [Example 2]

[0161] In the process of preparing the ceramic slurry, the weight ratio of the zirconia sintered powder with respect to the total weight of the zirconia sintered powder and the zirconia unsintered powder is set to 20% by weight, and otherwise, the electrolyte sheet of Example 2 is produced in the same manner as the electrolyte sheet of Example 1.

[0162] [Example 3]

[0163] In the process of preparing the ceramic slurry, the weight ratio of the zirconia sintered powder with respect to the total weight of the zirconia sintered powder and the zirconia unsintered powder is set to 50% by weight, and otherwise, the electrolyte sheet of Example 3 is produced in the same manner as the electrolyte sheet of Example 1.

[0164] [Example 4]

[0165] In the process of preparing the zirconia sintered powder, a zirconia sintered powder is obtained in which the particle diameter D 50 is 3.0 μm and the particle diameter D 99 is 7.9 μm, and otherwise, the electrolyte sheet of Example 4 is produced in the same manner as the electrolyte sheet of Example 1.

[0166] [Example 5]

[0167] In the process of preparing the ceramic slurry, the weight ratio of the zirconia sintered powder with respect to the total weight of the zirconia sintered powder and the zirconia unsintered powder was set to 5% by weight, and otherwise, the electrolyte sheet of Example 5 was manufactured in the same manner as the electrolyte sheet of Example 1.

[0168] [Example 6]

[0169] In the process of preparing the ceramic slurry, the weight ratio of the zirconia sintered powder with respect to the total weight of the zirconia sintered powder and the zirconia unsintered powder was set to 30% by weight, and otherwise, the electrolyte sheet of Example 6 was manufactured in the same manner as the electrolyte sheet of Example 1.

[0170] [Example 7]

[0171] In the process of preparing the ceramic slurry, the weight ratio of the zirconia sintered powder with respect to the total weight of the zirconia sintered powder and the zirconia unsintered powder was set to 40% by weight, and otherwise, the electrolyte sheet of Example 7 was manufactured in the same manner as the electrolyte sheet of Example 1.

[0172] [Comparative Example 1]

[0173] The process of preparing the zirconia sintered powder was not performed, that is, the zirconia sintered powder was not blended in the process of preparing the ceramic slurry, and otherwise, the electrolyte sheet of Comparative Example 1 was manufactured in the same manner as the electrolyte sheet of Example 1.

[0174] [Comparative Example 2]

[0175] In the process of preparing the zirconia sintered powder, the zirconia sintered powder having a particle size D 50 of 1.3 μm and a particle size D 99 of 4.1 μm was obtained, and otherwise, the electrolyte sheet of Comparative Example 2 was manufactured in the same manner as the electrolyte sheet of Example 1.

[0176] [Comparative Example 3]

[0177] In the process of preparing the zirconia sintered powder, the zirconia sintered powder having a particle size D 50 of 3.5 μm and a particle size D 99 of 8.2 μm was obtained, and otherwise, the electrolyte sheet of Comparative Example 3 was manufactured in the same manner as the electrolyte sheet of Example 1.

[0178] [Comparative Example 4]

[0179] In the process of preparing the ceramic slurry, the weight ratio of the zirconia sintered powder with respect to the total weight of the zirconia sintered powder and the zirconia unsintered powder was set to 55% by weight, and otherwise, the electrolyte sheet of Comparative Example 4 was manufactured in the same manner as the electrolyte sheet of Example 1.

[0180] Note that the above production conditions at the time of producing the electrolyte sheets of Examples 1 to 7 and Comparative Examples 1 to 4 are also shown in Table 1. In Table 1, the particle diameter D of the zirconia sintered powder obtained in the process of preparing the zirconia sintered powder 50 and the particle diameter D 99 are shown as "D 50 " and "D 99 ", respectively, and the weight ratio of the zirconia sintered powder in the process of preparing the ceramic slurry to the total weight of the zirconia sintered powder and the zirconia unsintered powder is shown as "weight ratio".

[0181] [Assessment]

[0182] For the electrolyte sheets of Examples 1 to 7 and Comparative Examples 1 to 4, the following assessment was performed.

[0183] <Particle size distribution of ceramic particles>

[0184] For the electrolyte sheets of Examples 1 to 7 and Comparative Examples 1 to 4, the probability distribution of the particle diameter of the ceramic particles was determined by the above method.

[0185] Figure 9 is a graph showing the probability distribution of the particle diameter of the ceramic particles of the electrolyte sheet of Example 1.

[0186] As shown in Figure 9 , it was confirmed that for the electrolyte sheet of Example 1, the probability distribution of the particle diameter of the ceramic particles was wide, and there were ceramic particles having a large particle diameter.

[0187] It was confirmed that for the electrolyte sheets of Examples 2 to 7, as well as for the electrolyte sheet of Example 1, the probability distribution of the particle diameter of the ceramic particles was wide, and there were ceramic particles having a large particle diameter. On the other hand, it was confirmed that for the electrolyte sheets of Comparative Examples 1 to 4, as compared with the electrolyte sheets of Examples 1 to 7, the probability distribution of the particle diameter of the ceramic particles was narrow.

[0188] In order to quantitatively express the above confirmation results, for the electrolyte sheets of Examples 1 to 7 and Comparative Examples 1 to 4, the number-based cumulative particle size distribution of the ceramic particles was determined by the above method.

[0189] Figure 10 is a graph showing the number-based cumulative particle size distribution of the ceramic particles of the electrolyte sheet of Example 1.

[0190] As shown in Figure 10 , for the electrolyte sheet of Example 1, in the number-based cumulative particle size distribution of the ceramic particles, the particle diameter D 50 (also referred to as the median particle diameter) at which the cumulative probability was 50% was 2.2 μm, and the particle diameter D 10D90 was 0.7 μm, and the difference between D50 and D10 was 3.1 μm. 90 D90 was 3.8 μm, and the difference between D50 and D10 was 3.1 μm. 90 D90 was 3.8 μm, and the difference between D50 and D10 was 3.1 μm. 10 D90 was 3.8 μm, and the difference between D50 and D10 was 3.1 μm.

[0191] For the electrolyte sheets of Examples 2 to 7 and Comparative Examples 1 to 4, D90, D50, D10, and the difference between D50 and D10 were also read from the cumulative particle size distribution on the number basis of the ceramic particles. 50 D90, D50, D10, and the difference between D50 and D10 were also read from the cumulative particle size distribution on the number basis of the ceramic particles. 10 D90, D50, D10, and the difference between D50 and D10 were also read from the cumulative particle size distribution on the number basis of the ceramic particles. 90 D90, D50, D10, and the difference between D50 and D10 were also read from the cumulative particle size distribution on the number basis of the ceramic particles. 90 D90, D50, D10, and the difference between D50 and D10 were also read from the cumulative particle size distribution on the number basis of the ceramic particles. 10 D90, D50, D10, and the difference between D50 and D10 were also read from the cumulative particle size distribution on the number basis of the ceramic particles. 50 D90, D50, D10, and the difference between D50 and D10 were also read from the cumulative particle size distribution on the number basis of the ceramic particles. 10 D90, D50, D10, and the difference between D50 and D10 were also read from the cumulative particle size distribution on the number basis of the ceramic particles. 90 D90, D50, D10, and the difference between D50 and D10 were also read from the cumulative particle size distribution on the number basis of the ceramic particles. 90 D90, D50, D10, and the difference between D50 and D10 were also read from the cumulative particle size distribution on the number basis of the ceramic particles. 10 D90, D50, D10, and the difference between D50 and D10 were also read from the cumulative particle size distribution on the number basis of the ceramic particles. 50 D90, D50, D10, and the difference between D50 and D10 were also read from the cumulative particle size distribution on the number basis of the ceramic particles. 10 D90, D50, D10, and the difference between D50 and D10 were also read from the cumulative particle size distribution on the number basis of the ceramic particles. 90 D90, D50, D10, and the difference between D50 and D10 were also read from the cumulative particle size distribution on the number basis of the ceramic particles. 90 D90, D50, D10, and the difference between D50 and D10 were also read from the cumulative particle size distribution on the number basis of the ceramic particles. 10 D90, D50, D10, and the difference between D50 and D10 were also read from the cumulative particle size distribution on the number basis of the ceramic particles.

[0192] <Strength>

[0193] For the electrolyte sheets of Examples 1 to 7 and Comparative Examples 1 to 4, the strength was evaluated as follows. First, in a precision universal testing machine "AGS-X" manufactured by Shimadzu Corporation, the electrolyte sheet was set at the center, a lower jig was set at an interval of 32.5 mm, and an upper jig was set at an interval of 65 mm. Then, by lowering the upper jig at a speed of 5 mm / minute, a 4-point bending test of the electrolyte sheet was performed, and the strength of the electrolyte sheet was measured. The strength of the electrolyte sheet thus measured is shown in Table 1 based on the following criteria.

[0194] O: The strength was 200 MPa or more.

[0195] X: The strength was less than 200 MPa.

[0196] <Conductivity>

[0197] The conductivity of the electrolyte sheet of Examples 1 to 7 and Comparative Examples 1 to 4 was evaluated as follows. First, a sample was prepared by forming an electrode on one side main surface of the electrolyte sheet. Next, after the sample was brought to a high temperature state of 864 ± 1°C and left for 30 minutes or more, the resistance of the sample in the high temperature state was measured three times at intervals of 2 minutes. Then, the conductivity was calculated from the measured values of the three resistances, and the average of these conductivities was defined as the conductivity in the high temperature state. Then, using the conductivity in the high temperature state, the conductivity of the electrolyte sheet was evaluated according to the following criteria. The results are shown in Table 1.

[0198] O: The conductivity in the high temperature state was 135 mS / cm or more.

[0199] Δ: The conductivity in the high temperature state was 125 mS / cm or more and less than 135 mS / cm.

[0200] X: The conductivity in the high temperature state was less than 125 mS / cm.

[0201]

[0202] As shown in Table 1, in the production of the electrolyte sheet of Example 1, in the process of preparing the zirconia sintered powder, a zirconia sintered powder was obtained in which the difference between the particle size D 50 was 3 μm or less and the particle size D 99 was 6 μm or more, and further, in the process of preparing the ceramic slurry, the weight ratio of the zirconia sintered powder to the total weight of the zirconia sintered powder and the zirconia unsintered powder was set to 50% by weight or less. In this case, in the electrolyte sheet of Example 1, in the cumulative particle size distribution on the number basis of the ceramic particles, the difference between the particle size D 90 and the particle size D 10 was 2.5 μm or more, and the strength was high. In addition, in the electrolyte sheet of Example 1, the conductivity in the high temperature state was as high as 125 mS / cm or more.

[0203] As shown in Table 1, in the production of the electrolyte sheet of Comparative Example 1, the process of preparing the zirconia sintered powder was not performed, that is, the zirconia sintered powder was not blended in the process of preparing the ceramic slurry. In this case, in the electrolyte sheet of Comparative Example 1, in the cumulative particle size distribution on the number basis of the ceramic particles, the difference between the particle size D 90 and the particle size D 10 was less than 2.5 μm, and the strength was low.

[0204] As shown in Table 1, in the production of the electrolyte sheet of Comparative Example 2, in the process of preparing the zirconia sintered powder, a zirconia sintered powder was obtained in which the particle size D 50 was 3 μm or less but the particle size D 99Zirconia sintered powder having a particle size D 90 of 3 μm or less but a particle size D 10 of less than 6 μm. In this case, in the electrolyte sheet of Comparative Example 2, in the cumulative particle size distribution on a number basis of ceramic particles, the particle size D

[0205] It should be noted that it was confirmed that even if the electrolyte sheet was manufactured by the manufacturing method described in Patent Document 1, as in the case of manufacturing the electrolyte sheet of Comparative Example 2, in the process of preparing the zirconia sintered powder, zirconia sintered powder having a particle size D 50 of 3 μm or less but a particle size D 99 of less than 6 μm was obtained. Therefore, it was confirmed that in the electrolyte sheet manufactured by the manufacturing method described in Patent Document 1, as in the case of the electrolyte sheet of Comparative Example 2, when the thickness was thinned to 120 μm, in the cumulative particle size distribution on a number basis of ceramic particles, the particle size D 90 of 3 μm or less but a particle size D 10 of less than 6 μm, the strength became low.

[0206] As shown in Table 1, in the process of preparing the zirconia sintered powder when manufacturing the electrolyte sheet of Comparative Example 3, zirconia sintered powder having a particle size D 99 of 6 μm or more but a particle size D 50 of more than 3 μm was obtained. In this case, in the electrolyte sheet of Comparative Example 3, in the cumulative particle size distribution on a number basis of ceramic particles, the particle size D 90 of 6 μm or more but a particle size D 10 of more than 3 μm, the strength became low.

[0207] As shown in Table 1, in the process of preparing the ceramic slurry when manufacturing the electrolyte sheet of Comparative Example 4, the weight ratio of the zirconia sintered powder with respect to the total weight of the zirconia sintered powder and the zirconia unsintered powder was set to be more than 50% by weight. In this case, in the electrolyte sheet of Comparative Example 4, in the cumulative particle size distribution on a number basis of ceramic particles, the particle size D 90 of 6 μm or more but a particle size D 10 of more than 3 μm, the strength became low.

[0208] Symbol explanation

[0209] 1 g of green ceramic sheet

[0210] 1 s of unsintered plate-like body

[0211] 1 t of green ceramic tape

[0212] 10, 130 electrolyte sheet for solid oxide fuel cell (electrolyte sheet)

[0213] 10p ceramic plate-like body

[0214] 100 single cell for solid oxide fuel cell (single cell)

[0215] 110 fuel electrode

[0216] 120 air electrode

[0217] X direction of casting

[0218] Y direction perpendicular to the direction of casting

Claims

1. An electrolyte sheet for a solid oxide fuel cell, characterized in that, It consists of ceramic plates containing sintered zirconium oxide. In the cumulative particle size distribution based on the number of ceramic particles, the particle size D with a cumulative probability of 90% is... 90 With a cumulative probability of 10%, particle size D 10 The difference is greater than 2.5 μm and less than 3.5 μm. The particle size D 90 The size is 3μm to 4μm. The particle size D 10 The size ranges from 0.5μm to 1μm.

2. A method for manufacturing an electrolyte sheet for a solid oxide fuel cell, characterized in that, have: Prepare particle size D with a cumulative probability of 50% in the cumulative particle size distribution based on volume. 50 Particle size D is less than 3 μm and has a cumulative probability of 99%. 99 The process for sintering zirconium oxide powder with a diameter of 6μm or larger; The process of preparing a ceramic slurry by mixing the sintered zirconia powder and the unsintered zirconia powder such that the weight ratio of the sintered zirconia powder to the total weight of the sintered zirconia powder and the unsintered zirconia powder is 5% to 50% by weight. The process of producing ceramic green sheets by molding the ceramic slurry; and In the process of producing a ceramic plate by sintering an unsintered plate containing the ceramic green sheet, the cumulative particle size distribution of the ceramic plate, based on the number of ceramic particles, shows that the particle size D has a cumulative probability of 90%. 90 With a cumulative probability of 10%, particle size D 10 The difference between the particle size D and the particle size D is greater than 2.5 μm and less than 3.5 μm. 90 The particle size D is 3μm to 4μm. 10 The size ranges from 0.5μm to 1μm.

3. The method for manufacturing an electrolyte sheet for a solid oxide fuel cell according to claim 2, wherein, In the process of preparing the ceramic slurry, the sintered zirconia powder and the unsintered zirconia powder are mixed such that the weight ratio of the sintered zirconia powder to the total weight of the sintered zirconia powder and the unsintered zirconia powder is 5% to 30% by weight.

4. A single cell for a solid oxide fuel cell, characterized in that, have: fuel electrode, air pole, and The electrolyte sheet for a solid oxide fuel cell according to claim 1 is disposed between the fuel electrode and the air electrode.

5. The method for manufacturing an electrolyte sheet for a solid oxide fuel cell according to claim 2 or 3, wherein, The unsintered zirconia powder has a particle size D that has a cumulative probability of 50% in the volume-based cumulative particle size distribution. 50 Particle size D is 0.1 μm to 0.3 μm and has a cumulative probability of 99%. 99 The size ranges from 1.5μm to 2.5μm.

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