Metal support cell and method for manufacturing a metal support cell.

Abstract

The present invention provides a metal support cell and a method for manufacturing a metal support that can ensure the reliability of cell strength even when the metal support layer creeps. [Solution] A metal support cell is provided in which one electrode layer (one of the cathode layer and one of the anode layer), an electrolyte layer, and the other electrode layer (one of the cathode layer and one of the anode layer) are laminated in this order on a metal support layer. In this metal support cell, at room temperature, the electrolyte layer and one of the electrode layers have compressive residual stress along the plane direction, and the metal support layer has tensile residual stress along the plane direction. Furthermore, the electrolyte layer is composed of multiple layers, and the magnitude of the compressive residual stress between adjacent layers differs.

Description

Technical Field

[0001] The present invention relates to a metal-supported cell and a method for manufacturing the metal-supported cell.

Background Art

[0002] Conventionally, a metal-supported cell (MSC: Metal-Supported Cell) having excellent mechanical strength, rapid start-up performance, etc. has been applied to a solid oxide fuel cell (SOFC: Solid Oxide Fuel Cell; hereinafter simply referred to as "SOFC").

[0003] The metal-supported cell is configured by laminating a plurality of layers including an electrolyte layer, an electrode layer, and a metal support layer. In order to ensure the strength reliability of the electrolyte layer formed from a brittle ceramic, each layer is controlled so that a compressive stress is constantly applied to the electrolyte layer.

[0004] When a compressive stress is applied to the electrolyte layer, the tensile stress, which is the reaction force, will be borne by the metal support layer. Here, if creep (stress relaxation) occurs in the metal support layer due to long-term high-temperature operation, the tensile stress that the metal support layer can bear will decrease, and there is a risk that the compressive stress (cell strength) applied to the electrolyte layer will decrease.

[0005] Patent Document 1 (WO2019 / 198372 A1) discloses a metal-supported cell having two metal support layers. In this metal-supported cell, the curing shrinkage rate of each phase during cell firing is controlled so that a compressive residual stress is retained in the metal support layer on the surface side and a tensile residual stress is retained in the internal metal support layer.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] In the metal-supported cell described in Patent Document 1, internal stresses in the cell are canceled out, and warping of the cell can be suppressed, thus allowing stronger compressive residual stress to be applied to the electrolyte layer. However, there is still a problem in that the cell strength decreases when the metal support layer creeps due to long-term operation.

[0008] In view of the above-mentioned problems, the present invention aims to provide a metal support cell and a method for manufacturing a metal support that can ensure the reliability of cell strength even when the metal support layer creeps. [Means for solving the problem]

[0009] According to one aspect of the present invention, a metal support cell is provided in which one electrode layer (one of a cathode layer and one of anode layers), an electrolyte layer, and the other electrode layer (one of a cathode layer and one of anode layers) are laminated in this order on a metal support layer. In this metal support cell, at room temperature, the electrolyte layer and one of the electrode layers have compressive residual stress along the plane direction, and the metal support layer has tensile residual stress along the plane direction. Furthermore, the electrolyte layer is composed of multiple layers, and the magnitude of the compressive residual stress between adjacent layers differs. [Effects of the Invention]

[0010] According to the present invention, the electrolyte layer is divided into two or more layers, and there is a difference in the magnitude of compressive residual stress between adjacent electrolyte layers. That is, the electrolyte layer has layers with compressive residual stress higher than the average value of the entire electrolyte layer and layers with compressive residual stress lower than the average value. Therefore, cracks are less likely to occur in layers with compressive residual stress higher than the average value, and even if cracks occur in the metal support layer or layers with compressive residual stress lower than the average value, gas leakage between electrodes can be prevented. In other words, the reliability of the cell strength is ensured even if the metal support layer creeps. [Brief explanation of the drawing]

[0011] [Figure 1]Figure 1 is an exploded perspective view showing a fuel cell stack according to an embodiment of the present invention. [Figure 2] Figure 2 is an exploded perspective view of the cell unit shown in Figure 1. [Figure 3] Figure 3 is an exploded perspective view of the metal support cell assembly shown in Figure 2. [Figure 4] Figure 4 is a partial cross-sectional view of the metal support cell assembly along line AA in Figure 2. [Figure 5] Figure 5 is a magnified partial cross-sectional view showing the metal support cell shown in Figure 4. [Figure 6] Figure 6 is a partial cross-sectional view illustrating the internal stresses in each layer of the metal support cell. [Figure 7] Figure 7 is a flowchart illustrating the manufacturing method of a metal support cell. [Figure 8] Figure 8 shows the temperature and internal stress of the metal support cell or its precursor during the firing shrinkage process, cooling process, operation, and creep generation. [Figure 9] Figure 9 illustrates the effects of this embodiment. [Modes for carrying out the invention]

[0012] Embodiments of the present invention will be described below with reference to the drawings. A method for manufacturing an electric cell according to an embodiment of the present invention will be described. Note that the dimensional ratios in the drawings are exaggerated for illustrative purposes and may differ from the actual ratios.

[0013] A metal support cell (MSC) 10 according to an embodiment of the present invention will be described with reference to Figures 1 to 5. The metal support cell 10 of this embodiment is used in a solid oxide fuel cell (SOFC).

[0014] For the sake of clarity in the following explanation, the XYZ Cartesian coordinate system is shown in the diagram. The X and Y axes represent the horizontal direction, and the Z axis represents the vertical direction, both parallel to each other.

[0015] FIG. 1 is an exploded perspective view showing a fuel cell stack 1 formed by stacking a plurality of cell units 1U according to the first embodiment in the vertical direction. Hereinafter, the vertical direction of the fuel cell stack 1 indicated by the Z axis in the figure is also referred to as the "stacking direction". Also, the plane direction of each layer constituting the cell unit 1U corresponds to the XY plane direction.

[0016] (Cell unit 1U) FIG. 2 is an exploded perspective view of the cell unit 1U. As shown in FIG. 2, the cell unit 1U is formed by stacking a metal support cell assembly 1A, a separator 120 having a flow path portion 121 for partitioning and forming a gas flow path, and a current collecting auxiliary layer 130. Note that a contact material for electrically connecting the metal support cell assembly 1A and the current collecting auxiliary layer 130 may be disposed between them, or a structure in which the current collecting auxiliary layer 130 is omitted may be adopted.

[0017] FIG. 3 is an exploded perspective view of the metal support cell assembly 1A, and FIG. 4 is a partial cross-sectional view of the metal support cell assembly 1A. As shown in FIGS. 3 and 4, the metal support cell assembly 1A includes a metal support cell 10 and a cell frame 113 that holds the outer periphery of the metal support cell 10.

[0018] (Metal support cell 10) FIG. 5 is a partial cross-sectional view showing an enlarged view of the metal support cell 10 shown in FIG. 4. As shown in FIGS. 3 to 5, the metal support cell 10 is formed by stacking a plurality of layers including an electrolyte layer 40, electrode layers 30, 50, and a metal support layer 60. The electrode layers 30, 50 include a cathode layer 30 and an anode layer 50. Hereinafter, the cathode layer 30 and the anode layer 50 may also be collectively referred to as the electrode layers 30, 50.

[0019] As shown in Figure 5, the metal support cell 10 is constructed by sequentially stacking a cathode layer 30, an electrolyte layer 40, an anode layer 50, and a metal support layer 60. The electrode layers 30, 50, and the electrolyte layer 40 constitute the electrolyte electrode assembly 20. The metal support layer 60 supports the electrolyte electrode assembly 20. The metal support cell 10 is suitable for use in SOFCs because it has superior mechanical strength and rapid startup properties compared to electrolyte-supported cells and electrode-supported cells.

[0020] (Electrolyte electrode assembly 20) As shown in Figures 3 to 5, the electrolyte electrode assembly 20 is constructed by laminating a cathode layer 30 on one side of an electrolyte layer 40 and an anode layer 50 on the other side.

[0021] (Cathode layer 30) The cathode layer 30 is an oxidizing electrode that reacts with a cathode gas (e.g., oxygen contained in air) and electrons to convert oxygen molecules into oxide ions. The cathode layer 30 comprises a porous conductive ceramic and a cathode catalyst supported on the conductive ceramic. The conductive ceramic is not particularly limited, but examples include scandia-stabilized zirconia (SSZ). The thickness of the cathode layer 30 is also not particularly limited, but is, for example, 0.3 to 50 μm. However, the material and thickness of the cathode layer 30 are selected to satisfy the relationship between the coefficients of linear expansion and the in-plane stiffness of each layer, which will be described later.

[0022] (Electrolyte layer 40) As shown in Figure 5, the electrolyte layer 40 according to this embodiment has an upper layer (third electrolyte layer) 41 positioned adjacent to the cathode layer 30, a lower layer (first electrolyte layer) 42 positioned adjacent to the anode layer 50, and an intermediate layer 43 (second electrolyte layer) sandwiched between the upper layer 41 and the lower layer 42. Because the electrolyte layer 40 has a three-layer structure in this way, no bending moment is generated within the electrolyte layer 40, and deformation of the metal support cell 10 is suppressed.

[0023] The electrolyte layer 40 is configured to allow oxide ions to conduct but not to permeate gases. The electrolyte layer 2 is formed of ceramics, and examples of ceramics include solid oxide ceramics. Examples of solid oxide ceramics include zirconia-containing materials. Examples of zirconia-containing materials include stabilized zirconia doped with yttria, neodymium oxide, samarium, gadolinium, and scandium. The thickness of the electrolyte layer 2 is not particularly limited, but is for example 0.5 to 20 μm. However, the material and thickness of the electrolyte layer 40 (upper layer 41, lower layer 42, intermediate layer 43) are selected to satisfy the relationship between the coefficients of linear expansion and the relationship between the in-plane stiffness of each layer, which will be described later.

[0024] (Anode layer 50) The anode layer 50 is a fuel electrode that reacts an anode gas (e.g., hydrogen) with oxide ions to produce an oxide of the anode gas and extract electrons. The anode layer 50 can also employ a configuration similar to that of the cathode layer 30. For example, the anode layer 50 has a porous conductive ceramic and an anode catalyst supported on the conductive ceramic. Examples of conductive ceramics include scandia-stabilized zirconia (SSZ). The thickness of the anode layer 50 is not particularly limited, but is for example 0.3 to 50 μm. However, the material and thickness of the anode layer 50 are selected to satisfy the relationship between the coefficients of linear expansion and the in-plane stiffness of each layer described later.

[0025] (metal support layer 60) As shown in Figures 3 and 4, the metal support layer 60 supports the electrolyte electrode assembly 20 from the anode layer 50 side. By supporting the electrolyte electrode assembly 20 with the metal support layer 60, the mechanical strength of the electrolyte electrode assembly 20 can be improved and breakage can be suppressed. The metal support layer 60 is formed from a porous metal that has gas permeability and electronic conductivity.

[0026] As the metal forming the metal support layer 60, for example, stainless steel (SUS) containing nickel (Ni) or chromium (Cr) can be used. However, the material of the metal support layer 60 is selected so as to satisfy the relationship between the coefficients of linear expansion of each layer described later.

[0027] (Cell frame 113) As shown in Figures 3 and 4, the cell frame 113 holds the metal support cell 10 from the periphery. As shown in Figure 3, the cell frame 113 has an opening 113H. The metal support cell 10 is placed in the opening 113H of the cell frame 113. The outer circumference of the metal support cell 10 is joined to the inner edge of the opening 113H of the cell frame 113.

[0028] As shown in Figure 3, the cell frame 113 has an anode gas inlet 113a and an anode gas outlet 113b through which anode gas flows, and a cathode gas inlet 113c and a cathode gas outlet 113d through which cathode gas flows.

[0029] (Separator 120) As shown in Figure 2, the flow path portion 121 of the separator 120 is formed in a substantially straight shape such that the uneven shape extends in one direction (Y direction). As a result, the direction of gas flow along the flow path portion 121 is the Y direction.

[0030] As shown in Figure 2, the separator 120 has an anode gas inlet 125a and an anode gas outlet 125b through which anode gas flows, and a cathode gas inlet 125c and a cathode gas outlet 125d through which cathode gas flows.

[0031] (Current collection auxiliary layer 130) The current collection auxiliary layer 130 helps to improve electrical contact between the metal support cell 10 and the separator 120 by equalizing the surface pressure while forming a space through which gas can pass. The current collection auxiliary layer 130 can be formed, for example, from a wire mesh-like expanded metal.

[0032] [Internal stress of each layer of metal support cell 10] Figure 6 is a partial cross-sectional view illustrating the internal stress of each layer of the metal support cell 10. The metal support cell 10 is formed such that each layer has internal stress by a manufacturing method described later. Figure 6 shows a half-cell consisting of an electrolyte layer 40, an anode layer 50, and a metal support layer 60, which are precursors to the metal support cell 10. The internal stress of the cathode layer 30 is preferably the same as that of the anode layer 50, but is not necessarily limited to this. Figure 6 also shows the internal stress of the laminate constituting the metal support cell 10 after high-temperature firing and cooling to room temperature, i.e., the internal stress at room temperature before SOFC operation. In this specification, "internal stress" includes compressive residual stress and tensile residual stress, and means stress that the material itself possesses or generates inside each layer regardless of external force.

[0033] As shown in Figure 6, the electrolyte layer 40 and the anode layer (electrode layer) 50 have compressive residual stress (internal stress in the direction of the arrows in the figure) along the XY plane, and the metal support layer 60 has tensile residual stress (internal stress in the direction of the arrows in the figure) along the XY plane.

[0034] Furthermore, the electrolyte layer 40 has different compressive residual stresses in its upper and lower layers 41 and 42 and in its intermediate layer 43. Specifically, the compressive residual stresses in the upper and lower layers 41 and 42 are greater than those in the intermediate layer 43.

[0035] The brittle ceramic material constituting the electrolyte layer 40 and the anode layer 50 has the characteristic of being weak under tensile stress and strong under compressive stress. By forming the electrolyte layer 40 and the anode layer 50 to have compressive residual stress as described above, it is possible to suppress the occurrence of cracks in the ceramic layer (especially the electrolyte layer 40).

[0036] On the other hand, the metal support layer 60 has ductile properties and is therefore strong against tensile stress. By structuring the metal support layer 60, which is strong against tensile stress, to bear the reaction force against compressive residual stress, the strength of the metal support cell 10 is ensured.

[0037] In this case, if a metal-supported cell (SOFC) operating at high temperatures is operated for a long period of time, creep (stress relaxation) may occur in the metal support layer of the metal-supported cell, reducing the tensile stress that the metal support layer can withstand and potentially decreasing the compressive stress (cell strength) on the electrolyte layer. If the compressive stress of the electrolyte layer decreases and cracks occur in the electrolyte layer, gas leaks between electrodes may occur. In contrast, in this embodiment, the electrolyte layer 40 is divided into multiple layers, and there is a difference in the magnitude of compressive residual stress between adjacent electrolyte layers. That is, the electrolyte layer 40 has layers (upper and lower layers 41, 42) and layers (intermediate layer 43) with compressive residual stress higher than the average value of the compressive residual stress experienced by the entire electrolyte layer 40. Therefore, cracks are less likely to occur in the layers with compressive residual stress higher than the average value (upper and lower layers 41, 42), and even if cracks occur in the metal support layer 60 or in the layers with compressive residual stress lower than the average value (intermediate layer 43), gas leaks between electrodes can be prevented. In other words, even if the metal support layer 60 creeps, the reliability of the cell strength is ensured.

[0038] [Coefficient of linear expansion of each layer of metal support cell 10] In the temperature range from room temperature (e.g., approximately 15°C to 30°C) to firing temperature (e.g., approximately 1000°C to 1400°C), the coefficient of linear expansion (CTE) is generally larger for the metal support layer 60, which is made of a metallic material, than for the electrolyte layer 40 and anode layer 50, which contain ceramic materials. Furthermore, in this embodiment, the materials for the anode layer 50 and the electrolyte layer 40 are selected such that the coefficient of linear expansion of the anode layer (electrode layer) 50 is greater than that of the electrolyte layer 40. That is, in this embodiment, the relationship between the coefficients of linear expansion of the metal support cell 10 is such that the coefficient of linear expansion of the electrolyte layer 40 < the coefficient of linear expansion of the anode layer 50 < the coefficient of linear expansion of the metal support layer 60.

[0039] Furthermore, in this embodiment, the materials for the upper and lower layers 41, 42 and the intermediate layer 43 are selected such that the coefficient of thermal expansion of the intermediate layer 43 of the electrolyte layer 40 is greater than the coefficients of thermal expansion of the upper and lower layers 41, 42. That is, the relationship between the coefficients of thermal expansion in the electrolyte layer 40 is such that the coefficients of thermal expansion of the upper and lower layers 41, 42 < the coefficient of thermal expansion of the intermediate layer 43.

[0040] As described later, when manufacturing the metal support cell 10, during the cooling process after high-temperature firing shrinkage, differences in thermal shrinkage occur between layers due to the relative magnitudes of the linear expansion coefficients of each layer. Then, in-plane elastic deformation occurs in the direction that eliminates this difference in thermal shrinkage, and the displacement of the joint (intermediate body of the metal support cell 10) is determined where the forces are balanced. In this process, the stress state of each layer is determined, and the smaller the linear expansion coefficient, the smaller the thermal shrinkage, and therefore the larger the compressive stress from the other layers. Accordingly, as in this embodiment, by setting the linear expansion coefficient of the electrolyte layer 40 to the smallest possible value, a large compressive residual stress is imparted to the electrolyte layer 40 at room temperature. Furthermore, since the linear expansion coefficients of the anode layer 50 and the electrolyte layer 40 are smaller than those of the metal support layer 60, tensile residual stress is imparted to the metal support layer 60 and compressive residual stress to the anode layer 50 and the electrolyte layer 40 at room temperature. Furthermore, the greater the difference between the linear expansion coefficient of the electrolyte layer 40 and that of the other layers, the greater the compressive residual stress that can be imparted to the electrolyte layer 40.

[0041] Furthermore, in this embodiment, since the coefficient of linear expansion of the upper and lower layers 41 and 42 is smaller than that of the intermediate layer 43 of the electrolyte layer 40, a large compressive residual stress is applied to the upper and lower layers 41 and 42 at room temperature. As a result, cracks are less likely to occur in the upper and lower layers 41 and 42, and even if cracks occur in the metal support layer 60 or the intermediate layer 43 of the electrolyte layer 40, gas leakage between electrodes can be prevented.

[0042] [In-plane rigidity of each layer of metal support cell 10] In this embodiment, the materials and thicknesses of the electrolyte layer 40 and the anode layer 50 are selected such that the relationship between the magnitudes of the in-plane stiffness calculated by thickness × elastic modulus is such that the in-plane stiffness of the electrolyte layer 40 > the in-plane stiffness of the anode layer 50. The in-plane stiffness of the metal support layer 60, which is made of metal, is greater than the in-plane stiffness of the electrolyte layer 40 and the electrode layers (anode layer 50, cathode layer 30).

[0043] Furthermore, in this embodiment, the materials and thicknesses of the upper and lower layers 41 and 42 and the intermediate layer 43 are selected such that the in-plane stiffness of the upper and lower layers 41 and 42 of the electrolyte layer 40 is greater than the in-plane stiffness of the intermediate layer 43. That is, the relationship of in-plane stiffness in the electrolyte layer 40 is such that the in-plane stiffness of the upper and lower layers 41 and 42 > the in-plane stiffness of the intermediate layer 43.

[0044] In the metal support cell 10 of this embodiment, tensile residual stress is applied to the metal support layer 60, and compressive residual stress is applied to the electrolyte layer 40 and the anode layer 50. However, the magnitude of the compressive residual stress borne by the electrolyte layer 40 and the anode layer 50 also depends on the in-plane stiffness of each layer. That is, the greater the in-plane stiffness, the greater the compressive residual stress applied. In this embodiment, since the in-plane stiffness of the electrolyte layer 40 is greater than that of the anode layer 50, a larger compressive residual stress is applied to the electrolyte layer 40. As a result, the strength of the electrolyte layer 40 is increased, and the occurrence of cracks in the electrolyte layer 40 is suppressed.

[0045] Furthermore, in this embodiment, the in-plane rigidity of the upper and lower layers 41 and 42 is greater than the in-plane rigidity of the intermediate layer 43 of the electrolyte layer 40, so that a large compressive residual stress is applied to the upper and lower layers 41 and 42 at room temperature. As a result, cracks are less likely to occur in the upper and lower layers 41 and 42, and even if cracks occur in the metal support layer 60 or the intermediate layer 43 of the electrolyte layer 40, gas leakage between electrodes can be prevented.

[0046] [Method for manufacturing metal support cell 10] Next, the manufacturing method of the metal support cell 10 will be described with reference to Figures 7 and 8.

[0047] In the following description, we will explain the manufacturing method of a half-cell composed of an electrolyte layer 40, an anode layer 50, and a metal support layer 60, which are precursors to the metal support cell 10, and will omit the method for forming the cathode layer 30.

[0048] Figure 7 is a flowchart illustrating the manufacturing method of the metal support cell 10. As shown in Figure 7, the manufacturing method of the metal support cell 10 includes a slurry preparation step (S1), a coating step (S2), a bonding step (S3), a firing shrinkage step (S4), and a cooling step (S5).

[0049] In this embodiment, the internal stress of the metal support cell 10 is controlled by adjusting the timing of the firing and hardening of each layer in the firing shrinkage process, the cooling shrinkage rate of each layer in the cooling process due to the coefficient of linear expansion (CTE) of each layer, and the in-plane stiffness of each layer.

[0050] (Slurry preparation process) First, in the slurry preparation step (S1), the slurry raw materials are mixed to prepare the first electrolyte slurry, the second electrolyte slurry, the third electrolyte slurry, the anode slurry, and the metal-supported slurry. A known stirring device can be appropriately selected and used for mixing the slurry raw materials.

[0051] The first to third electrolyte slurries are formed by mixing slurry raw materials that mainly consist of ceramics, along with a solvent, sintering aid, and binder.

[0052] Anode slurry is formed by mixing slurry raw materials that consist mainly of ceramics, along with a solvent, sintering aid, and binder.

[0053] Metal-supported slurry is formed by mixing slurry raw materials that consist mainly of metal, along with a solvent, sintering aid, and binder.

[0054] Suitable solvents for the slurry include, but are not particularly limited, water and / or alcoholic solvents such as methanol, ethanol, 1-propanol (NPA), 2-propanol, ethylene glycol, and propylene glycol, and organic solvents such as N-methyl-2-pyrrolidone (NMP). These solvents may be used individually or in mixtures of two or more. The amount of solvent used is preferably adjusted so that the viscosity of the slurry is suitable for forming into a sheet.

[0055] The binder added to the slurry can be any known organic binder that is appropriately selected. Examples of organic binders include ethylene copolymers, styrene copolymers, acrylate copolymers, methacrylate copolymers, vinyl butyral resins, vinyl acetal resins, vinyl formal resins, vinyl alcohol resins, and celluloses such as ethyl cellulose.

[0056] Furthermore, plasticizers, dispersants, and other additives may be added to each slurry as needed.

[0057] In the manufacturing method according to this embodiment, the timing of the firing and hardening of each layer is controlled by adjusting the material particle size, the variation in material particle size distribution, and the sphericity of the material particles in each layer, thereby controlling the firing shrinkage rate of each layer in the subsequent firing shrinkage process. Specifically, the materials for the electrolyte layer 40 and the anode layer 50 are selected such that the material particle size, the variation in material particle size distribution, and the sphericity of the material particles of the electrolyte layer 40 are smaller than those of the anode layer 50, respectively. That is, the relationship between the size of the material particle size is such that the material particle size of the electrolyte layer 40 < the material particle size of the anode layer 50, the relationship between the variation in the distribution of material particle size is such that the variation in the distribution of material particle size of the electrolyte layer 40 < the variation in the distribution of material particle size of the anode layer 50, and the relationship between the size of the sphericity of the material particles is such that the sphericity of the material particles of the electrolyte layer 40 < the sphericity of the material particles of the anode layer 50. The smaller the material particle size, the greater the variation in the distribution of material particle size, and the smaller the sphericity of the material particles, the faster the firing shrinkage rate and the earlier the timing of hardening shrinkage. Therefore, by making the material particle size, the greater the variation in the distribution of material particle size, and the sphericity of the material particles of the electrolyte layer 40 smaller than those of the anode layer 50, the timing of hardening shrinkage of the electrolyte layer 40 becomes earlier than the timing of hardening shrinkage of the anode layer 50.

[0058] Furthermore, the materials for the upper and lower layers 41 and 42 and the intermediate layer 43 are selected such that the material particle size, the variation in the distribution of material particle size, and the sphericity of the material particles in the upper and lower layers 41 and 42 of the electrolyte layer 40 are smaller than those of the intermediate layer 43. Specifically, the relative sizes of the material particle sizes are such that the material particle size of the upper and lower layers 41 and 42 < the material particle size of the intermediate layer 43, the relative sizes of the variation in the distribution of material particle size are such that the variation in the distribution of material particle size of the upper and lower layers 41 and 42 < the variation in the distribution of material particle size of the intermediate layer 43, and the relative sizes of the sphericity of the material particles are such that the sphericity of the material particles in the upper and lower layers 41 and 42 < the sphericity of the material particles in the intermediate layer 43. Consequently, the timing of hardening shrinkage of the upper and lower layers 41 and 42 is earlier than the timing of hardening shrinkage of the intermediate layer 43. Details of the firing shrinkage process will be described later.

[0059] (Coating process) Next, in the coating process (S2), each slurry prepared in the slurry preparation process is formed into a sheet using a sheet forming method such as tape casting with coating equipment such as knife coating or doctor blade. After drying the obtained sheet-like slurry, a first electrolyte sheet, a second electrolyte sheet, a third electrolyte sheet, an anode electrode sheet, and a metal support sheet can be obtained by heat treatment as needed. The first electrolyte sheet, second electrolyte sheet, third electrolyte sheet, anode electrode sheet, and metal support sheet are generally called green sheets.

[0060] (Bonding process) Next, in the bonding process (S3), the first electrolyte sheet, the second electrolyte sheet, the third electrolyte sheet, the anode electrode sheet, and the metal support sheet are sequentially laminated and bonded together to form a laminate.

[0061] (Shrinkage during firing process) Next, the firing shrinkage process (S4) and the cooling process (S5) will be explained with reference to Figure 8. Figure 8 shows the temperature and internal stress of the metal support cell 10 or its precursor during the firing shrinkage process, the cooling process, operation of the metal support cell 10 (SOFC), and when creep occurs in the metal support layer 60.

[0062] In the firing shrinkage process, the internal stress of the metal support cell 10 is controlled by controlling the timing of the firing hardening of each layer. Specifically, the relative magnitudes of the firing shrinkage rates are set so that electrolyte layer 40 > anode layer 50 > metal support layer 60, causing the electrolyte layer 40, anode layer 50, and metal support layer 60 to harden and shrink in that order. In this way, by setting the timing of the hardening shrinkage of the electrolyte layer 40 to be earlier than that of the anode layer 50, compressive stress is applied to the electrolyte layer 40 and tensile stress to the anode layer 50 at the completion of the firing shrinkage process. That is, as shown in Figure 8, at the completion of the firing shrinkage process, the electrolyte layer 40 is in the compression region and the anode layer (electrode layer) 50 is in the tensile region. Even if the residual stress due to the difference in linear expansion coefficients is relieved by going through the subsequent processes of cooling, operation, and creep, the final stress distribution maintains the influence at the completion of the firing shrinkage process. That is, even after creep occurs, the compressive residual stress of the electrolyte layer 40 is greater than that of the anode layer 50. Therefore, even after creep occurs, the electrolyte layer 40 remains under compressive residual stress, ensuring cell strength. In contrast, in conventional examples, as shown in Figure 8, after creep occurs, the electrolyte layer moves to the tensile region, which can lead to cracks in the electrolyte layer and gas leakage. However, since the anode layer (electrode layer) 50 is a porous material, even if some cracks occur, it will not lead to gas leakage between electrodes. Therefore, a decrease in the compressive residual stress of the anode layer (electrode layer) 50 is acceptable.

[0063] Furthermore, in this embodiment, the relationship between the firing shrinkage rates in the electrolyte layer 40 is such that the firing shrinkage rate of the upper and lower layers 41 and 42 > the firing shrinkage rate of the intermediate layer 43, so that the electrolyte layer 40 hardens and shrinks in the order of the upper and lower layers 41 and 42, and then the intermediate layer 43. By making the timing of the hardening shrinkage of the upper and lower layers 41 and 42 earlier than the timing of the hardening shrinkage of the intermediate layer 43, a large compressive residual stress can be applied to the upper and lower layers 41 and 42 of the electrolyte layer 40 at room temperature (RT) when the cooling process is completed, and a difference in compressive residual stress can be created between the upper and lower layers 41 and 42 and the intermediate layer 43. As a result, cracks are less likely to occur in the upper and lower layers 41 and 42, and even if cracks occur in the metal support layer 60 or the intermediate layer 43 of the electrolyte layer 40 after creep occurs in the metal support layer 60, gas leakage between electrodes can be prevented.

[0064] As described above, in this embodiment, the timing of curing shrinkage of the electrolyte layer 40 is made earlier than that of the anode layer 50 by making the material particle size, the variation in the distribution of material particle size, and the sphericity of the material particles of the electrolyte layer 40 smaller than that of the anode layer 50. Furthermore, the timing of curing shrinkage of the upper and lower layers 41 and 42 is made earlier than that of the intermediate layer 43 by making the material particle size, the variation in the distribution of material particle size, and the sphericity of the material particles of the upper and lower layers 41 and 42 smaller than that of the intermediate layer 43.

[0065] In the firing shrinkage process, the laminate is degreased and co-fired. The firing temperature can be, for example, 1000°C to 1400°C. The first electrolyte slurry and third electrolyte slurry → second electrolyte slurry → anode slurry → metal support slurry harden and shrink (harden) in that order.

[0066] First, the first electrolyte slurry and the third electrolyte slurry are fired and hardened to form the upper and lower layers 41 and 42 of the electrolyte layer 40. Next, the second electrolyte slurry is fired and hardened to form the intermediate layer 43 of the electrolyte layer 40. Then, the anode slurry is fired and hardened to form the anode layer 50, and the metal support slurry is fired and hardened to form the metal support layer 60. At this time, the hardening shrinkage of the anode layer 50 and the metal support layer 60 imparts compressive residual stress to the adjacent electrolyte layer 40. Tensile residual stress is imparted to the anode layer 50 and the metal support layer 60 as a reaction force to the compressive residual stress of the electrolyte layer 40. Furthermore, the compressive residual stress imparted to the electrolyte layer 40 is greater in the upper and lower layers 41 and 42 than in the intermediate layer 43.

[0067] In this embodiment, the electrolyte layer 40 has a three-layer structure, and the upper and lower two layers 41 and 42 are located outside the intermediate layer 43. As a result, heat is supplied to the upper and lower two layers 41 and 42 faster during firing. This also speeds up the firing and hardening rate of the upper and lower two layers 41 and 42, and allows for the application of high compressive residual stress to the upper and lower two layers 41 and 42.

[0068] (cooling process) In the cooling process (S5), the metal support cell 10 is cooled. Cooling is performed by leaving it at room temperature RT (e.g., 15°C to 30°C) to cool naturally. Natural cooling may be performed in a reducing atmosphere to prevent oxidation, or in the atmosphere.

[0069] As mentioned above, in the temperature range from room temperature to firing temperature, the relative magnitudes of the linear expansion coefficients of the multiple layers are as follows: linear expansion coefficient of electrolyte layer 40 < linear expansion coefficient of anode layer 50 < linear expansion coefficient of metal support layer 60. Therefore, the relative magnitudes of the shrinkage amounts in the cooling process are as follows: shrinkage amount of electrolyte layer 40 < shrinkage amount of anode layer 50 < shrinkage amount of metal support layer 60. As a result, in the temperature range from room temperature to operating temperature (approximately 600-800°C) in the practical application range, compressive residual stress can be applied to the electrolyte layer 40 and anode layer 50, which have relatively small linear expansion coefficients, and furthermore, a larger compressive residual stress can be applied to the electrolyte layer 40, which has an even smaller linear expansion coefficient. Therefore, as shown in Figure 8, even when creep occurs in the metal support layer 60, the electrolyte layer 40 is in the compression region, and even if cracks occur in the metal support layer 60, gas leakage between electrodes can be prevented.

[0070] Furthermore, in the temperature range from room temperature to firing temperature, the relationship between the linear expansion coefficients in the electrolyte layer 40 is such that the linear expansion coefficients of the upper and lower layers 41 and 42 are less than that of the intermediate layer 43. Therefore, the relationship between the shrinkage amounts in the cooling process is such that the shrinkage amount of the upper and lower layers 41 and 42 is less than that of the intermediate layer 43. As a result, in the temperature range from room temperature to operating temperature in the practical application area, the upper and lower layers 41 and 42, which have relatively small linear expansion coefficients, are subjected to a compressive residual stress greater than the average compressive residual stress of the electrolyte layer 40. Therefore, as shown in Figure 8, even after creep occurs in the metal support layer 60, the upper and lower layers 41 and 42 of the electrolyte layer 40 maintain a larger compressive residual stress than the intermediate layer 43. Consequently, cracks are less likely to occur in the upper and lower layers 41 and 42 even after creep occurs, and even if cracks occur in the metal support layer 60 or the intermediate layer 43 of the electrolyte layer 40 after creep occurs, the upper and lower layers 41 and 42 can prevent gas leakage between electrodes.

[0071] Furthermore, in the temperature range from room temperature to firing temperature, the relative magnitudes of the in-plane stiffness of the multiple layers are such that the in-plane stiffness of the electrolyte layer 40 > the in-plane stiffness of the anode layer 50. As mentioned above, in the cooling process after the firing shrinkage process, the linear expansion coefficients of the electrolyte layer 40 and the anode layer 50 are smaller than those of the metal support layer 60, so tensile residual stress is imparted to the metal support layer 60, and compressive residual stress is imparted to the electrolyte layer 40 and the anode layer 50. The magnitude of the compressive residual stress borne by the electrolyte layer 40 and the anode layer 50 also depends on the in-plane stiffness of each layer; the greater the in-plane stiffness, the greater the compressive residual stress imparted. Therefore, at room temperature, a larger compressive residual stress can be imparted to the electrolyte layer 40, which has relatively high in-plane stiffness, and cell strength is ensured even if the metal support layer 60 creeps. As mentioned above, even if some cracks occur in the anode layer (electrode layer) 50, this does not lead to gas leakage between electrodes, so a decrease in the compressive residual stress of the anode layer (electrode layer) 50 is acceptable.

[0072] Furthermore, in the temperature range from room temperature to firing temperature, the relationship of in-plane stiffness in the electrolyte layer 40 is such that the in-plane stiffness of the upper and lower layers 41 and 42 > the in-plane stiffness of the intermediate layer 43. Therefore, at room temperature, the upper and lower layers 41 and 42 can be given greater compressive residual stress. As a result, cracks are less likely to occur in the upper and lower layers 41 and 42, and even if cracks occur in the metal support layer 60 or the intermediate layer 43 of the electrolyte layer 40 after creep occurs, gas leakage between electrodes can be better prevented.

[0073] Figure 9 illustrates the effects of this embodiment and shows the magnitude of internal stress in each layer as a function of the operating time of the metal support cell 10 (SOFC).

[0074] As shown in Figure 9, the tensile residual stress of the metal support layer 60 decreases as the operating time increases. In conventional metal-supported cells consisting of a single electrolyte layer, as the tensile residual stress of the metal support layer decreases, the compressive residual stress of the electrolyte layer decreases, and the electrolyte layer moves into the tensile region where tensile stress is applied. Consequently, cracks may form in the electrolyte layer, potentially leading to gas leaks.

[0075] In contrast, the metal support cell 10 of this embodiment has a three-layer structure in which the electrolyte layer 40 has upper and lower layers 41, 42 and an intermediate layer 43, and the compressive residual stress of the upper and lower layers 41, 42 is greater than the average compressive residual stress of the electrolyte layer 40. Therefore, even if the tensile residual stress of the metal support layer 60 decreases, only the intermediate layer 43 moves to the tensile region, while the upper and lower layers 41, 43 remain in the compressive region. Consequently, even if the tensile residual stress of the metal support layer 60 decreases, cracks are less likely to occur in the upper and lower layers 41, 43, and even if cracks occur in the metal support layer 60 and the intermediate layer 43 of the electrolyte layer 40, gas leakage between electrodes can be prevented.

[0076] According to the metal support cell 10 and the method for manufacturing the metal support cell 10 of the above-described embodiment, the following effects can be obtained.

[0077] The metal support cell 10 has an anode layer 50, an electrolyte layer 40, and a cathode layer 30 stacked in this order on a metal support layer 60. At room temperature, the electrolyte layer 40 and the anode layer 50 have compressive residual stress along the plane direction, and the metal support layer 60 has tensile residual stress along the plane direction. The electrolyte layer 40 is composed of multiple layers (upper layer 41, lower layer 42, intermediate layer 43), and the magnitude of the compressive residual stress differs between adjacent layers. Thus, the electrolyte layer 40 is divided into multiple layers, and there is a difference in the magnitude of the compressive residual stress between adjacent electrolyte layers. That is, the electrolyte layer 40 has layers (upper and lower layers 41, 42) and layers (intermediate layer 43) with a compressive residual stress higher than the average value of the compressive residual stress experienced by the entire electrolyte layer 40. Therefore, cracks are less likely to occur in layers with compressive residual stress higher than the average value (upper and lower layers 41, 42), and even if cracks occur in the metal support layer 60 or in layers with compressive residual stress lower than the average value (intermediate layer 43), gas leakage between electrodes can be prevented. In other words, the reliability of the cell strength is ensured even if the metal support layer 60 creeps.

[0078] In the metal support cell 10, the relationship between the coefficients of linear expansion is such that the coefficient of linear expansion of the electrolyte layer 40 < the coefficient of linear expansion of the anode layer 50 (one of the electrode layers) < the coefficient of linear expansion of the metal support layer 60. This allows compressive residual stress to be applied to the electrolyte layer 40 and the anode layer 50, which have relatively small coefficients of linear expansion, and furthermore, a larger compressive residual stress can be applied to the electrolyte layer 40, which has an even smaller coefficient of linear expansion. Therefore, even when creep occurs in the metal support layer 60, the electrolyte layer 40 remains in the compression region, and gas leakage between electrodes can be prevented even if cracks occur in the metal support layer 60.

[0079] The metal support cell 10 has an electrolyte layer 40 consisting of three layers: an upper layer 41, a lower layer 42, and an intermediate layer 43 sandwiched between the upper and lower layers 41 and 42. The coefficient of linear expansion of the intermediate layer 43 is greater than that of the upper and lower layers 41 and 42. As a result, in the temperature range from room temperature to operating temperature in the practical range, the upper and lower layers 41 and 42, which have relatively small coefficients of linear expansion, are subjected to a compressive residual stress greater than the average compressive residual stress of the electrolyte layer 40. Therefore, even after creep occurs in the metal support layer 60, the upper and lower layers 41 and 42 of the electrolyte layer 40 maintain a larger compressive residual stress than the intermediate layer 43. Consequently, cracks are less likely to occur in the upper and lower layers 41 and 42 even after creep occurs, and even if cracks occur in the metal support layer 60 or the intermediate layer 43 of the electrolyte layer 40 after creep occurs, the upper and lower layers 41 and 42 can prevent gas leakage between electrodes.

[0080] Furthermore, because the electrolyte layer 40 has a three-layer structure, no bending moment is generated within the electrolyte layer 40, and deformation of the metal support cell 10 is suppressed.

[0081] In the metal-supported cell 10, the in-plane stiffness relationship is such that the in-plane stiffness of the electrolyte layer 40 is greater than that of the anode layer 50 (one of the electrode layers). As a result, at room temperature, a larger compressive residual stress is applied to the electrolyte layer 40, which has relatively greater in-plane stiffness, and the cell strength is ensured even if the metal support layer 60 creeps.

[0082] In the metal support cell 10, the electrolyte layer 40 has greater in-plane rigidity in the upper and lower layers 41 and 42 than in the intermediate layer 43. This allows for greater compressive residual stress in the upper and lower layers 41 and 42 at room temperature. Consequently, cracks are less likely to occur in the upper and lower layers 41 and 42, and even if the metal support layer 60 creeps and cracks occur in the metal support layer 60 or the intermediate layer 43 of the electrolyte layer 40, gas leakage between electrodes can be better prevented.

[0083] In the manufacturing method of the metal support cell 10 of this embodiment, the relative rates of firing shrinkage are: firing shrinkage rate of the electrolyte layer 40 > firing shrinkage rate of the anode layer 50 (one of the electrode layers) > firing shrinkage rate of the metal support layer 60. As a result, in the firing shrinkage process of the manufacturing process of the metal support cell 10, the electrolyte layer 40, anode layer 50, and metal support layer 60 harden and shrink in that order. By setting the timing of the hardening shrinkage of the electrolyte layer 40 to be earlier than the timing of the hardening shrinkage of the anode layer 50, compressive stress is applied to the electrolyte layer 40 and tensile stress to the anode layer 50 at the completion of the firing shrinkage process. In this state, even if residual stress due to the difference in coefficients of linear expansion is relieved through subsequent processes such as cooling, operation, and creep, the final stress distribution maintains the effect at the completion of the firing shrinkage process. That is, even after creep occurs in the metal support layer 60, the compressive residual stress of the electrolyte layer 40 is greater than that of the anode layer 50, ensuring cell strength.

[0084] In the manufacturing method of the metal support cell 10 of this embodiment, the material particle size of the anode layer 50 (one electrode layer) is larger than that of the electrolyte layer 40, the variation in the material particle size distribution of the anode layer 50 (one electrode layer) is larger than that of the electrolyte layer 40, and the sphericity of the material particles of the anode layer 50 (one electrode layer) is larger than that of the material particles of the electrolyte layer 40. As a result, in the firing shrinkage process, the timing of the hardening shrinkage of the electrolyte layer 40 can be made earlier than the timing of the hardening shrinkage of the anode layer 50. Therefore, when the firing shrinkage process is completed, compressive stress is applied to the electrolyte layer 40 and tensile stress is applied to the anode layer 50, and even after creep occurs in the metal support layer 60, the compressive residual stress of the electrolyte layer 40 is greater than that of the anode layer 50, ensuring cell strength.

[0085] In the manufacturing method of the metal support cell 10 of this embodiment, the firing shrinkage rate of the upper and lower layers 41 and 42 of the electrolyte layer 40 is greater than the firing shrinkage rate of the intermediate layer 43. As a result, in the firing shrinkage process, the timing of the hardening shrinkage of the upper and lower layers 41 and 42 is earlier than the timing of the hardening shrinkage of the intermediate layer 43. Therefore, at room temperature when the cooling process is completed, a large compressive residual stress can be applied to the upper and lower layers 41 and 42 of the electrolyte layer 40, and a difference in compressive residual stress can be created between the upper and lower layers 41 and 42 and the intermediate layer 43. As a result, cracks are less likely to occur in the upper and lower layers 41 and 42, and even if cracks occur in the metal support layer 60 or the intermediate layer 43 of the electrolyte layer 40 after creep occurs in the metal support layer 60, gas leakage between electrodes can be prevented.

[0086] According to the manufacturing method of the metal support cell 10 of this embodiment, the electrolyte layer 40 has a material particle size of the intermediate layer 43 that is larger than the material particle size of the upper and lower two layers 41 and 42, the variation in the material particle size distribution of the intermediate layer 43 is larger than the variation in the material particle size distribution of the upper and lower two layers 41 and 42, and the sphericity of the material particles of the intermediate layer 43 is larger than the sphericity of the material particles of the upper and lower two layers 41 and 42. As a result, the timing of hardening shrinkage of the upper and lower layers 41 and 42 can be made earlier than the timing of hardening shrinkage of the intermediate layer 43. Therefore, at room temperature when the cooling process is completed, a large compressive residual stress can be applied to the upper and lower layers 41 and 42 of the electrolyte layer 40, and a difference in compressive residual stress can be created between the upper and lower two layers 41 and 42 and the intermediate layer 43. As a result, cracks are less likely to occur in the upper and lower layers 41 and 42, and even if cracks occur in the metal support layer 60 or the intermediate layer 43 of the electrolyte layer 40 after creep occurs in the metal support layer 60, gas leakage between electrodes can be prevented.

[0087] In this embodiment, the metal support cell 10 is configured to have one metal support layer 60, but it is not limited to this configuration, and it may also have a metal support layer (second metal support layer) on the cathode layer 30. In this case, the structure becomes symmetrical between the anode side and the cathode side with respect to the electrolyte layer 40, and the cell strength is increased.

[0088] Furthermore, while it is preferable that the electrolyte layer 40 is composed of three layers, as in this embodiment, it is not necessarily limited to this. That is, the electrolyte layer 40 may be composed of multiple layers with different compressive residual stresses between adjacent layers, for example, two layers with different compressive residual stresses. Even in this case, the same effect as in this embodiment can be obtained by making the compressive residual stress of one layer of the electrolyte layer 40 higher than the average value of the compressive residual stresses of the electrolyte layer 40. That is, cracks are less likely to occur in the one layer, and even if cracks occur in the metal support layer 60 or the other layer of the electrolyte layer 40 after creep occurs in the metal support layer 60, gas leakage between electrodes can be prevented.

[0089] In this embodiment, the metal support cell 10 is constructed by stacking an anode layer 50, an electrolyte layer 40, and a cathode layer 30 on a metal support layer 60 in that order. However, the stacking order of the anode layer 50 and the cathode layer 30 (i.e., the electrode layers) may be reversed. That is, the cathode layer 30, electrolyte layer 40, and anode layer 50 may be stacked on the metal support layer 60 in that order.

[0090] Furthermore, in this embodiment, the firing shrinkage rate is controlled by the material particle size, the variation in the distribution of material particle size, and the sphericity of the material particles. However, the method for controlling the firing shrinkage rate is not limited to this, and it may be controlled by any known method.

[0091] Furthermore, as in this embodiment, it is preferable that the relationship between the coefficients of linear expansion is such that the coefficient of linear expansion of the electrolyte layer 40 < the coefficient of linear expansion of the anode layer 50 (one electrode layer) < the coefficient of linear expansion of the metal support layer 60, but it is not necessarily limited to this, and the coefficients of linear expansion of the electrolyte layer 40 and the anode layer 50 (one electrode layer) may be equal. That is, the relationship between the coefficients of linear expansion may be such that the coefficient of linear expansion of the electrolyte layer 40 ≤ the coefficient of linear expansion of the anode layer 50 (one electrode layer) < the coefficient of linear expansion of the metal support layer 60. Even in this case, compressive residual stress can be applied to the electrolyte layer 40 and the anode layer 50, which have relatively small coefficients of linear expansion.

[0092] Although embodiments of the present invention have been described above, these embodiments only represent a part of the application examples of the present invention, and are not intended to limit the technical scope of the present invention to the specific configurations of the above embodiments. [Explanation of Symbols]

[0093] 10...Metal support cell, 30...Cathode layer, 40...Electrolyte layer, 41...Upper layer, 42...Lower layer, 43...Intermediate layer, 50...Anode layer, 60...Metal support layer

Claims

1. A metal support cell is formed by stacking one electrode layer (a cathode layer and an anode layer), an electrolyte layer, and the other electrode layer (a cathode layer and an anode layer) on a metal support layer in this order. At room temperature, the electrolyte layer and the one electrode layer have compressive residual stress along the plane direction, and the metal support layer has tensile residual stress along the plane direction. The electrolyte layer is composed of multiple layers, and these multiple layers have different magnitudes of compressive residual stress between adjacent layers. Metal support cell.

2. A metal support cell according to claim 1, The relationship between the coefficients of linear expansion is such that the coefficient of linear expansion of the electrolyte layer ≤ the coefficient of linear expansion of one of the electrode layers < the coefficient of linear expansion of the metal support layer. Metal support cell.

3. A metal support cell according to claim 2, The electrolyte layer consists of three layers: an upper layer, a lower layer, and an intermediate layer sandwiched between the upper and lower layers, wherein the coefficient of linear expansion of the intermediate layer is greater than that of the upper and lower two layers. Metal support cell.

4. A metal support cell according to any one of claims 1 to 3, The relationship between the magnitudes of in-plane stiffness, calculated by thickness × elastic modulus, is such that the in-plane stiffness of the electrolyte layer > the in-plane stiffness of one of the electrode layers. Metal support cell.

5. A metal support cell according to claim 4, The electrolyte layer consists of three layers: an upper layer, a lower layer, and an intermediate layer sandwiched between the upper and lower layers, wherein the in-plane rigidity of the upper and lower layers is greater than the in-plane rigidity of the intermediate layer. Metal support cell.

6. A metal support cell according to claim 1, further comprising a second metal support layer laminated on the other electrode layer, Metal support cell.

7. A method for manufacturing a metal support cell according to claim 1, comprising stacking one electrode layer (one of the cathode layer and the anode layer), an electrolyte layer, and the other electrode layer (one of the cathode layer and the anode layer) on a metal support layer in this order, and then firing and shrinking, The relative magnitudes of the firing shrinkage rates are as follows: firing shrinkage rate of the electrolyte layer > firing shrinkage rate of one of the electrode layers > firing shrinkage rate of the metal support layer. A method for manufacturing metal support cells.

8. A method for manufacturing a metal support cell according to claim 7, The material particle size of one of the electrode layers is larger than the material particle size of the electrolyte layer, The variation in the particle size distribution of the material in one of the electrode layers is greater than the variation in the particle size distribution of the material in the electrolyte layer. The sphericity of the material grains in one of the electrode layers is greater than the sphericity of the material grains in the electrolyte layer. A method for manufacturing metal support cells.

9. A method for manufacturing a metal support cell according to claim 7 or 8, The electrolyte layer consists of three layers: an upper layer, a lower layer, and an intermediate layer sandwiched between the upper and lower layers, wherein the firing shrinkage rate of the upper and lower layers is greater than the firing shrinkage rate of the intermediate layer. A method for manufacturing metal support cells.

10. A method for manufacturing a metal support cell according to claim 9, The electrolyte layer has a material particle size in the intermediate layer that is larger than the material particle size in the upper and lower two layers. The variation in the particle size distribution of the intermediate layer is greater than the variation in the particle size distribution of the upper and lower layers. The sphericity of the material grains in the intermediate layer is greater than the sphericity of the material grains in the upper and lower two layers. A method for manufacturing metal support cells.

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