JP2013077395A - Anode substrate, solid oxide fuel cell and manufacturing method of anode substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an anode substrate capable of compatibly achieving gas permeability and mechanical strength.SOLUTION: An anode substrate 16 includes a first main surface 16p, an undulating second main surface 16q, a bank part 30 to be in contact with a separator 20 of a fuel cell 100, and a recessed part 32 formed thinner than the bank part 30. The anode substrate 16 has a planar shape as a whole. A surface of the bank part 30 and a surface of the recessed part 32 are present on the same plane to form the first main surface 16p. Undulation of the second main surface 16q is formed due to a difference in thickness between the bank part 30 and the recessed part 32.

Description

  The present invention relates to an anode substrate, a solid oxide fuel cell, and a method for manufacturing an anode substrate.

  Fuel cells are attracting attention as a next-generation clean energy source, and their research and development are rapidly progressing. A solid oxide fuel cell is known as one of the fuel cells. The solid oxide fuel cell has, for example, a flat plate structure in which a large number of plate cells including an anode, a solid electrolyte layer, and a cathode are stacked. The flat plate type solid oxide fuel cell has a feature that the output density per unit volume is higher than that of the cylindrical solid oxide fuel cell.

  In order to improve the power generation performance of the solid oxide fuel cell, it is effective to make the solid electrolyte layer dense and thin. However, the thinner the solid electrolyte layer, the easier it is for the cell to crack due to the stack load. In order to make the solid electrolyte layer thin, a fuel cell using an anode as a support (anode substrate) has been proposed (Patent Documents 1 and 2).

JP 2011-060695 A JP 2005-196981 A

  The anode substrate is required to have sufficient gas permeability. On the other hand, high mechanical strength is also required for the anode substrate. When the anode substrate is thinned, the gas permeability increases, but the mechanical strength decreases. That is, in the anode substrate, gas permeability and mechanical strength are in a trade-off relationship. If the anode substrate is too thick, the material cost may increase.

  An object of this invention is to provide the anode substrate which can make gas permeability and mechanical strength compatible, and its manufacturing method. Another object of the present invention is to provide a solid oxide fuel cell using the anode substrate.

That is, the present invention
An anode substrate for supporting a solid electrolyte layer of a solid oxide fuel cell,
The first main surface,
A undulating second main surface,
A bank portion to be in contact with a separator of the fuel cell;
And a hollow portion formed thinner than the bank portion,
The anode substrate has a flat plate shape as a whole,
The first main surface is formed by the surface of the bank portion and the surface of the recess portion being on the same plane,
Provided is an anode substrate in which the undulation of the second main surface is formed due to a difference in thickness between the bank portion and the recess portion.

In another aspect, the present invention provides:
The anode substrate of the present invention;
A cathode,
A solid electrolyte layer disposed between the anode substrate and the cathode;
A solid oxide fuel cell is provided.

In yet another aspect, the present invention provides:
A method for manufacturing an anode substrate for supporting a solid electrolyte layer of a solid oxide fuel cell, comprising:
Preparing a flat first ceramic green sheet;
Preparing a second ceramic green sheet having an opening;
Bonding the first ceramic green sheet and the second ceramic green sheet to each other so that a laminate of the first ceramic green and the second ceramic green sheet is formed;
Firing the laminate;
A method for manufacturing an anode substrate is provided.

  The anode substrate of the present invention includes a bank portion and a recess portion. On the first main surface side, the surface of the bank portion is on the same plane as the surface of the recess portion. Due to the difference in thickness between the bank portion and the recess portion, the undulation of the second main surface is formed. When such a structure is employed, the mechanical strength per unit weight can be increased. Furthermore, since the hollow portion is thinner than the bank portion, the resistance when the fuel gas passes through the anode substrate is reduced. As a result, sufficient gas permeability is ensured. Therefore, according to the present invention, an anode substrate having both excellent gas permeability and high mechanical strength can be provided. Since the mechanical strength per unit weight can be increased, material costs can be saved.

  If the anode substrate of the present invention is used, a solid oxide fuel cell having excellent power generation performance and high reliability can be provided.

  According to the method of the present invention, the above anode substrate can be easily and inexpensively manufactured.

1 is a perspective view of a solid oxide fuel cell according to an embodiment of the present invention. 1 is a perspective view of an anode substrate used in the fuel cell shown in FIG. Sectional drawing which shows the positional relationship of the fuel gas supply groove | channel of a separator, and the hollow part of an anode substrate Manufacturing process diagram of power generation element including anode, solid electrolyte layer and cathode (A) Plan view of anode substrate according to modification example (b) Cross-sectional view of anode substrate according to another modification example (c) Plan view and side view of anode substrate according to another modification example Plan view of anode substrates according to Examples 1 to 6

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the present invention is not limited to the following embodiments.

  As shown in FIG. 1, the solid oxide fuel cell 100 of this embodiment includes a power generation element 24, a first separator 20, and a second separator 22. The power generation element 24 is sandwiched between the first separator 20 and the second separator 22 so as to be in electrical contact therewith. The power generation element 24 includes the anode 10, the solid electrolyte layer 12, and the cathode 14. The solid electrolyte layer 12 is disposed between the anode 10 and the cathode 14. The anode 10 has a thickness that sufficiently exceeds the sum of the thickness of the solid electrolyte layer 12 and the thickness of the cathode 14. The solid electrolyte layer 12 and the cathode 14 are supported by the anode 10. The anode 10 serves as a support that supports the solid electrolyte layer 12 and the cathode 14. That is, the fuel cell 100 is an anode supported and flat plate type solid oxide fuel cell.

  The power generation element 24 has a square shape, typically a square shape, in plan view. However, the shape of the power generation element 24 is not particularly limited. The shape of the power generation element 24 in plan view may be other shapes such as a circle and a polygon.

The solid electrolyte layer 12 is made of a ceramic containing yttria-stabilized zirconia, scandia-stabilized zirconia, or the like as a main component. The solid electrolyte layer 12 has a thickness in the range of 5 to 30 μm, for example. The cathode 14 is made of a porous ceramic containing lanthanum manganite or the like as a main component. The cathode 14 has a thickness in the range of 10 to 70 μm, for example. In the present embodiment, the cathode 14 is in direct contact with the solid electrolyte layer 12. However, a barrier layer may be provided between the cathode 14 and the solid electrolyte layer 12 according to the combination of the material of the solid electrolyte layer 12 and the material of the cathode 14. The barrier layer is made of a ceramic containing CeO ₂ or the like as a main component. The barrier layer prevents the performance of the fuel cell 100 from being deteriorated due to the formation of the high resistance material layer due to the reaction between the material of the solid electrolyte layer 12 and the material of the cathode 14. Such a phenomenon can occur when the cathode 14 is fired to produce the power generation element 24 and during operation of the fuel cell 100. The “main component” means a component that is contained most by weight.

  The first separator 20 and the second separator 22 are each made of a refractory metal or a conductive ceramic. Separators 20 and 22 are also called interconnectors. The first separator 20 is configured to supply fuel gas to the anode 10 (the anode substrate 16 in the present embodiment). Specifically, the first separator 20 is formed with a plurality of fuel gas supply grooves 20a for supplying fuel gas to the anode 10 so as to extend in one direction. The fuel gas is typically hydrogen gas. The second separator 22 is configured to supply an oxidant gas to the cathode 14. Specifically, the second separator 22 is formed with a plurality of oxidant gas supply grooves 22a for supplying an oxidant gas to the cathode 14 so as to extend in the other direction. The oxidant gas is typically air.

  The anode 10 includes an anode substrate 16 and an anode active layer 18. The anode substrate 16 and the anode active layer 18 are typically made of a porous ceramic containing nickel oxide and zirconia as main components. The anode substrate 16 has a thickness in the range of 150 to 1500 μm, for example. The anode active layer 18 has a thickness in the range of 5 to 30 μm, for example. The anode substrate 16 is different from the anode active layer 18 in that the main purpose is to maintain the mechanical strength of the power generation element 24 and it does not substantially carry out an electrochemical reaction related to power generation. The anode active layer 18 serves as a reaction field that generates water vapor and electrons by the reaction between hydrogen and oxygen ions. However, when the anode substrate 16 can function as the anode 10 alone, the anode active layer 18 can be omitted.

  As shown in FIG. 2, the anode substrate 16 has a first main surface 16p and a second main surface 16q. The first main surface 16p is a main surface that should be in contact with the anode active layer 18. When the anode active layer 18 is omitted, the first main surface 16p is a main surface that should be in contact with the solid electrolyte layer 12. The second main surface 16q is a main surface that should be in contact with the first separator 20. As shown in FIG. 2, the second main surface 16q is provided with undulations. In this specification, the “main surface” means a surface having the largest area.

  The anode substrate 16 includes a bank portion 30 and a recess portion 32. The bank portion 30 is a portion that should be in contact with the first separator 20. The hollow portion 32 is a portion formed thinner than the bank portion 30. The anode substrate 16 has a flat plate shape as a whole. The first main surface 16p is formed by the surface of the bank portion 30 and the surface of the recess portion 32 being on the same plane. That is, the first main surface 16p is a flat surface. The undulations of the second main surface 16q are formed due to the difference in thickness between the bank portion 30 and the recess portion 32. The bank 30 and the recess 32 improve the mechanical strength of the anode substrate 16 per unit weight. Further, sufficient gas permeability is ensured by the recess 32.

  In the present embodiment, a plurality of depressions 32 are provided so as to be individually surrounded by the bank 30. When the plurality of depressions 32 are provided, it is easy to supply the fuel gas to each of the depressions 32 from the fuel gas supply groove 20 a of the first separator 20. As shown in FIG. 3, in the fuel cell 100, the first separator 20 is in surface contact with the bank portion 30 of the anode substrate 16. Since the bank portion 30 has a constant thickness D, the adhesion between the anode substrate 16 and the first separator 20 is also good. The fuel gas supply groove 20a and the recess 32 communicate with each other so that the fuel gas is guided from the fuel gas supply groove 20a to the recess 32 of the anode substrate 16. Specifically, each of the plurality of depressions 32 faces one of the plurality of fuel gas supply grooves 20a. According to such a positional relationship, the fuel gas can be reliably supplied to the recess 32 through the fuel gas supply groove 20a. The fuel gas moves to the anode active layer 18 without staying inside the anode substrate 16, and is effectively used for the electrode reaction at the three-phase interface where the anode active layer 18, the solid electrolyte layer 12, and the fuel gas are in contact with each other. .

  As shown in FIG. 2, the anode substrate 16 has a so-called waffle appearance. That is, the undulation of the second main surface 16q shows a regular pattern. In the present embodiment, the regular pattern is a lattice pattern. The bank portion 30 constitutes a lattice portion, and the plurality of recess portions 32 constitutes a space portion of the lattice. According to the grid-like bank portion 30, it is possible to prevent directivity from being generated in the mechanical strength of the anode substrate 16. The regular pattern is not limited to the case where a plurality of depressions 32 having the same shape and the same dimensions are arranged according to a certain rule. For example, two or more types of depressions having different shapes may be arranged according to a certain rule. Two or more types of indentations having different dimensions (thickness, area in plan view) may be arranged according to a certain rule.

  The bank portion 30 includes a frame-shaped portion formed along the outer edge of the anode substrate 16. That is, the outermost peripheral portion of the anode substrate 16 is formed by the bank portion 30 such that all of the plurality of recessed portions 32 are located inside the bank portion 30 when the anode substrate 16 is viewed in plan. The side surface of the anode substrate 16 is formed by the bank 30 over the entire circumference. According to such a structure, since the frame-shaped part of the bank part 30 can contact the 1st separator 20, the gas seal in the fuel cell 100 becomes easy.

  The smaller the thickness of the hollow portion 32 is, the more material cost of the anode substrate 16 can be saved, and the superior gas permeability is exhibited. However, the thickness of the recess 32 should be adjusted in consideration of the mechanical strength of the anode substrate 16. As shown in FIG. 3, the thickness of the bank portion 30 (the thickness of the anode substrate 16 in the bank portion 30) is D, and the thickness of the recess portion 32 (the thickness of the anode substrate 16 in the recess portion 32) is d. In some cases, for example, the thickness d of the recess 32 can be adjusted so as to satisfy the relationship of 0.3D <d <D (preferably 0.6D <d <0.8D). When the thickness d of the recess 32 is appropriately adjusted, the gas permeability can be enhanced while ensuring sufficient mechanical strength of the anode substrate 16. Material costs can also be saved.

  From the same viewpoint, the proportion of the recess 32 in the anode substrate 16 is, for example, 35% or less, preferably 15 to 25% in terms of the surface area observed when the second main surface 16q is viewed in plan. It is. Thereby, gas permeability can be improved, ensuring sufficient mechanical strength of the anode substrate 16.

  In the present embodiment, the recess 32 has a square shape in plan view. On the second main surface 16q side, the space portion formed by the recess 32 has a rectangular parallelepiped shape. However, the planar view shape of the hollow part 32 is not specifically limited. The recess 32 may have other shapes such as a circle and a rhombus in plan view. The shape of the space portion is not particularly limited. The space portion may have other three-dimensional shapes such as a columnar shape, a hemispherical shape, and a weight shape.

  Next, a method for manufacturing the power generation element 24 will be described with reference to FIG.

  First, a conductive component, a skeleton component, and a solvent are mixed to prepare an anode substrate slurry. The anode substrate slurry is formed into a sheet by a method such as a doctor blade method. The obtained sheet-like molded body is dried. Thereby, a flat green sheet 160 (first ceramic green sheet) is obtained (STEP 1). As long as the solvent can be removed appropriately, the drying condition of the molded body is not particularly limited. For example, the drying temperature is 70 to 120 ° C., and the drying time is 1 to 10 hours. These conditions can also be applied to other drying processes described later.

  The conductive component is a component for imparting conductivity to the anode substrate 16. Conductive components include metals such as nickel, cobalt, iron, platinum, palladium, and ruthenium; metal oxides that change to conductive metals in a reducing atmosphere during fuel cell operation, such as nickel oxide, cobalt oxide, and iron oxide Articles: Complex metal oxides containing two or more of these metal oxides, such as nickel ferrite and cobalt ferrite. These may be used alone or in combination of two or more. Among these, nickel, cobalt, iron, or an oxide thereof can be preferably used.

The skeleton component is a component for ensuring mechanical strength and redox resistance. “Redox resistance” means chemical stability and strength stability when the anode substrate 16 is repeatedly exposed from an oxidizing atmosphere to a reducing atmosphere or from a reducing atmosphere to an oxidizing atmosphere. Examples of the skeleton component include zirconia, alumina, magnesia, titania, aluminum nitride, and mullite. A composite of these skeleton components can also be used. The most versatile is stabilized zirconia. Stabilized zirconia is a solid solution of zirconia and a stabilizer. Stabilizers include oxides of alkaline earth metals such as MgO, CaO, SrO, BaO; Y ₂ O ₃ , La ₂ O ₃ , CeO ₂ , Pr ₂ O ₃ , Nd ₂ O ₃ , Sm ₂ O ₃ , Eu ₂ O ₃ , Gd ₂ O ₃ , Tb ₂ O ₃ , Dy ₂ O ₃ , Er ₂ O ₃ , Tm ₂ O ₃ , Yb ₂ O ₃ oxides of rare earth elements; Sc ₂ O ₃ , Bi ₂ Examples thereof include oxides of transition metals such as O ₃ and In ₂ O ₃ . Stabilized zirconia may contain oxides such as alumina, titania, Ta ₂ O ₅ and Nb ₂ O ₅ as a dispersion strengthening agent. As skeleton components, CaO, SrO, BaO, Y ₂ O ₃ , La ₂ O ₃ , Ce ₂ O ₃ , Pr ₂ O ₃ , Nb ₂ O ₃ , Sm ₂ O ₃ , Eu ₂ O ₃ , Gd ₂ O ₃ , Tb ₂ O ₃ , Dr ₂ O ₃ , Ho ₂ O ₃ , Er ₂ O ₃ , Yb ₂ O ₃ , PbO, WO ₃ , MoO ₃ , V ₂ O ₅ , Ta ₂ O ₅ and Nb ₂ O ₅ A ceria-based ceramic or a bismuth-based ceramic in which at least one selected from the group consisting of CeO _{2 and} Bi ₂ O ₃ is added can also be used. Furthermore, a gallate ceramic such as LaGaO ₃ can also be used as a skeleton component. These may be used alone or in combination of two or more. Among these, as the skeleton component, stabilized zirconia, ceria-based ceramics, and lanthanum gallate are preferable, and stabilized zirconia is more preferable. Particularly preferred are zirconia stabilized with 2.5-12 mol% yttria or zirconia stabilized with 3-15 mol% scandia.

  In particular, the anode substrate slurry can be prepared so that the anode substrate 16 has the following composition. The skeleton component of the anode substrate 16 includes zirconia. This zirconia is a stabilized zirconia containing 2 to 11 mol% of a rare earth metal oxide or an alkaline earth metal oxide as a stabilizer, and further contains Al atoms. The amount of Al atoms contained in the zirconia is within a range where the molar ratio of Al atoms to Zr atoms (Al / Zr) satisfies 0.10 to 2.50.

  For example, stabilized zirconia containing 2.5 to 15 mol% of a rare earth metal oxide such as Sc, Y and Ce as a stabilizer, and 5 to 20 mol% of an alkaline earth metal oxide such as Mg and Ca. Is exemplified by stabilized zirconia containing as a stabilizer. These may be used in combination of two or more as required. Particularly preferred among these stabilized zirconia are 3-6 mol% yttria stabilized zirconia (YSZ) and 3-6 mol% scandia stabilized zirconia (ScSZ). .

  As described above, the amount of Al atoms contained in the stabilized zirconia is within a range where the molar ratio of Al atoms to Zr atoms (Al / Zr) is 0.10 to 2.50, preferably 0.25. It is in the range which becomes -2.00, More preferably, it exists in the range which becomes 0.50-1.50. Examples of the Al atom source added to the stabilized zirconia include alumina, aluminum hydroxide, and aluminum chloride. For example, when alumina is used as an additive, it is preferable to add 5 to 40% by mass of alumina with respect to the entire skeletal component, and to add 7.5 to 30% by mass. More preferably, it is more preferable to add so that it may become 10-25 mass%.

  A particularly preferable example is zirconia in which the zirconia contained in the anode substrate 16 is stabilized with 3 to 6 mol% yttria in which 20 mass% of alumina is uniformly dispersed.

  The anode substrate 16 of this embodiment can realize high mechanical strength of the cell by including stabilized zirconia to which alumina is added in the above-described range. It is desirable that the alumina is uniformly dispersed in the stabilized zirconia. Therefore, it is preferable that the stabilized zirconia powder in which alumina is uniformly dispersed is used as a raw material, and the anode substrate 16 of this embodiment is formed by a sintered body of the zirconium powder. In the anode substrate 16, 5% by mass or more of the skeleton component is preferably stabilized zirconia containing Al atoms in the above range. More preferably, the skeletal component of the anode substrate 16 is made of stabilized zirconia containing Al atoms in the above range. The skeletal component may contain ceria doped with oxides of rare earth elements such as Gd, Sm, and Y in addition to stabilized zirconia containing Al atoms.

  The ratio (W1: W2) between the mass W1 of the conductive component and the mass W2 of the skeleton component is, for example, 3: 7 to 8: 2, and preferably 4: 6 to 7: 3. “Mass of conductive component” means the mass when the conductive component is present as an oxide.

  The anode substrate slurry may contain additives such as a pore forming agent, a plasticizer, a binder and a dispersing agent. As these additives, those known in the field of solid oxide fuel cells can be appropriately used. These additives may be contained in the anode active layer slurry, the solid electrolyte layer slurry, and the cathode slurry described later.

  Next, as shown in STEP 2 of FIG. 5, the flat green sheet 160 is punched in a predetermined pattern so that a punched green sheet 161 (second ceramic green sheet) having a plurality of openings 32 h is obtained. That is, the punched green sheet 161 can be produced from the flat green sheet 160. The opening 32 h corresponds to a space formed by the recess 32 of the anode substrate 16. The plurality of openings 32 h are regularly arranged in the punched green sheet 161. The material, thickness, outer dimensions, and outer shape of the flat green sheet 160 are the same as those of the punched green sheet 161. In this way, material costs and production costs can be saved. However, the material and thickness of the flat green sheet 160 may be different from those of the punched green sheet 161.

  Next, as shown in STEP 3 in FIG. 5, the flat green sheet 160 and the punched green sheet 161 are bonded together. Thereby, the laminated body 162 of the flat green sheet 160 and the punching green sheet 161 is formed. In order to improve the adhesion between the flat green sheet 160 and the punched green sheet 161, the laminate 162 may be pressed as necessary.

  In this embodiment, the thickness of the punched green sheet 161 is equal to the thickness of the flat green sheet 160, and the outer dimension of the punched green sheet 161 is equal to the outer dimension of the flat green sheet 160. In this case, the number, size, and shape of the openings 32 h can be determined so that the area ratio occupied by the openings 32 h in the punched green sheet 161 is 35% or less with respect to the area of the main surface of the flat green sheet 160. . As will be described later, the anode substrate 16 having sufficient mechanical strength can be manufactured by adjusting the ratio of the opening 32h to 35% or less.

  If the shrinkage during firing is strictly considered, the ratio of the opening 32h in the punched green sheet 161 may not match the ratio of the recess 32 in the anode substrate 16. However, in this specification, these ratios are considered to be equal to each other before and after firing.

  A method of forming the laminate 162 without using the punched green sheet 161 can also be employed. For example, a flat laminate is formed by laminating a plurality of flat green sheets 160. Next, a part of the flat plate laminate is removed on one surface of the flat plate laminate so that a portion to be the depression 32 is formed. This removal step can be performed by laser processing or excavation processing that removes a part of the flat plate laminate with a sharp blade. In some cases, after the laminate 170 is fired, the recess 32 may be formed by laser processing or excavation processing.

  Next, as shown in STEP 4 of FIG. 5, the unfired anode active layer 180 and the unfired solid electrolyte layer 120 are formed in this order on the laminate 162 (specifically, on the flat green sheet 160). Thereby, the laminated body 170 is obtained. Specifically, the anode active layer slurry and the solid electrolyte layer slurry are printed in this order on the laminate 162 by a thin film forming method such as screen printing. As needed, the laminated body 170 is dried and the laminated body 170 is pressed. Thereafter, the laminate 170 is fired. The firing conditions are not particularly limited, and are adjusted according to the materials used. For example, the firing temperature is 1100 to 1500 ° C., and the firing time is 1 to 10 hours.

  As the anode active layer slurry, one having substantially the same composition as that of the anode substrate slurry can be used. In order to adjust the viscosity of the anode active layer slurry to a viscosity suitable for screen printing, the composition of the anode active layer slurry may be different from the composition of the anode substrate slurry. For example, the anode active layer slurry and the anode substrate include the type of binder, the amount of binder, the type of plasticizer, the amount of plasticizer, the particle size of powder used as a conductive component, and the particle size of powder used as a skeletal component. It can be different from the slurry for use.

  As the slurry for the solid electrolyte layer, a slurry containing a ceramic material and a solvent can be used. As the ceramic material for forming the solid electrolyte layer 12, a known material can be used as the material of the electrolyte layer of the solid oxide fuel cell. For example, zirconia stabilized with oxides such as yttrium oxide, cerium oxide, scandium oxide, ytterbium oxide; ceria doped with yttria, samaria, gadolinia, etc .; lanthanum gallate; Lanthanum gallate type perovskite structure oxides substituted with these elements (strontium, calcium, barium, magnesium, aluminum, indium, cobalt, iron, nickel, copper, etc.) can be used. These may be used alone or in combination of two or more. Among these, zirconia stabilized with yttrium oxide, scandium oxide, or ytterbium oxide is preferable.

  In particular, zirconia stabilized with 3-10 mol% yttrium oxide, 4-12 mol% zirconia stabilized with scandium oxide, zirconia stabilized with 8-12 mol% scandium oxide, 4-15 Zirconia stabilized with mol% ytterbium oxide, zirconia stabilized with 8-12 mol% scandium oxide and 0.5-5 mol% cerium oxide can be preferably used. A material in which an oxide such as alumina, silica, titania or the like is added to stabilized zirconia as a sintering aid or dispersion strengthener can also be suitably used.

  Finally, a slurry for cathode is applied onto the half-cell solid electrolyte layer 12 composed of the anode substrate 16, the anode active layer 18, and the solid electrolyte layer 12 by a thin film forming method such as screen printing, and unfired on the half-cell. A cathode layer is formed. And the laminated body comprised by the half cell and the unbaking cathode layer is baked. Thereby, the electric power generation element 24 is obtained (STEP 5).

As the cathode slurry, a slurry containing a ceramic material and a solvent can be used. As the ceramic material for forming the cathode 14, those known as cathode materials for solid oxide fuel cells can be used. The ceramic material for forming the cathode 14 is typically a perovskite oxide that has excellent electronic conductivity and is stable even in an oxidizing atmosphere. Specifically, lanthanum manganite, lanthanum ferrite and lanthanum cobaltite are well known as cathode materials. Examples of such a cathode material include La _0.8 Sr _0.2 MnO ₃ , La _0.6 Sr _0.4 CoO ₃ , La _0.6 Sr _0.4 FeO ₃ , and La _0.6 Sr _0.4 Co _0.2 Fe _0.8 O ₃ . Moreover, in order to provide oxygen ion conductivity to the cathode 14, the ceramic material for preparing the cathode slurry may contain ceria doped with rare earth elements or stabilized zirconia.

  In addition, in manufacture of the electric power generation element 24, the timing which performs a baking process, and the frequency | count of execution of a baking process are not limited. For example, an anode active layer slurry and a solid electrolyte layer slurry may be applied onto the baked anode substrate 16. However, according to the method of the present embodiment, the total number of firings is two. In the first firing step, the laminated body 170 including the laminated body 160 (punched green sheet 161 and flat green sheet 160), the unfired anode active layer 180, and the unfired solid electrolyte layer 120 is fired. In the second firing step, the laminate composed of the half cell and the unfired cathode layer is fired. According to such a method, improvement in productivity and reduction in production costs can be expected by reducing the number of firings as much as possible. Further, the second baking step can be performed at a temperature suitable for forming the cathode 14. Since the firing process is performed a plurality of times, the thickness of the unfired anode layer, the thickness of the unfired solid electrolyte layer, and the thickness of the unfired cathode layer can be accurately adjusted in the step of applying each slurry.

  According to the method described above, the anode substrate 16 is manufactured by firing the laminate 162 composed of the two green sheets 160 and 161. However, the number of green sheets used to form the anode substrate 16 is not limited to two. That is, the laminated body 162 may be formed by bonding three or more green sheets to each other. In this case, at least one green sheet may be constituted by the flat green sheet 160. For example, three flat green sheets 160 are produced, and a punched green sheet 161 is produced using one or two of them. When the laminated body 162 is formed by laminating one punched green sheet 161 and two flat green sheets 160, the thickness of the recessed portion 32 is 1/3 of the thickness of the bank portion 30. When the laminated body 162 is formed by laminating two punched green sheets 161 and one flat green sheet 160, the thickness of the recessed portion 32 is 2/3 of the thickness of the bank portion 30.

  Further, the method for forming the unfired anode active layer 180 and the unfired solid electrolyte layer 120 is not limited to screen printing. For example, the anode green sheet and the solid electrolyte green sheet are prepared by the same method as the flat green sheet 160 using the anode active layer slurry and the solid electrolyte layer slurry. The laminated body 170 can be formed by laminating the anode green sheet and the solid electrolyte green sheet on the laminated body 162 in this order.

(Modification)
In the anode substrate 16 shown in FIG. 2, the recess 32 has a square shape in plan view. However, the shape of the recess 32 is not particularly limited. Hereinafter, some modified examples will be described.

  The anode substrate 50 shown in FIG. 5A has a groove-like recess 42 extending in a specific direction. For other points, the description of the anode substrate 16 shown in FIG. 2 can be used. The anode substrate 60 shown in FIG. 5B has a plurality of depressions 44 that form hemispherical space portions. That is, the shape of the space portion formed by the recess is not particularly limited. The anode substrate 70 shown in FIG. 5C is composed of a plurality of protruding bank portions 40 and a flat plate portion as the recess 46. Each of the plurality of bank portions 40 is formed so as to protrude from the flat plate portion. The plurality of bank portions 40 are regularly arranged on the flat plate portion. Since the heights of the respective bank portions 40 are uniform, there is no possibility that the contact between the first separator 20 and the anode substrate 70 will be hindered. The shape of the bank portion 40 is not particularly limited. Various convex shapes such as a columnar shape, a prismatic shape, and a weight shape can be adopted for the bank portion 40. If the anode substrate 70 having such a structure is used in the fuel cell 100, the fuel gas supply groove 20a of the first separator 20 (see FIGS. 1 and 3) may be omitted. That is, since a space portion derived from the recess 46 is open on the side surface of the anode substrate 70, fuel gas can be supplied to the anode through the space portion.

Example 1
60 parts by mass of nickel oxide powder (manufactured by Shodo Chemical Co., Ltd., average particle diameter 0.7 μm, 90 vol% diameter 1.2 μm) as a conductive component, 3 mol% yttria-stabilized zirconia powder (first rare element company) as a skeletal component Manufactured, trade name “HSY-3.0”, average particle diameter 0.7 μm, 90 volume% diameter 1.9 μm) 40 parts by mass, carbon black as pore forming agent (manufactured by SEC Carbon, SGP-3, average 10 parts by mass of a particle diameter of 3.3 μm, 10% by volume of 1.5 μm), a mixed solvent of 60 parts by mass of toluene and 40 parts by mass of ethanol as a solvent, butyral resin as a binder (manufactured by Sekisui Chemical Co., Ltd., trade name “BM” -S ") 10 parts by weight, 3 parts by weight of dibutyl phthalate (made by Wako Pure Chemical Industries) as a plasticizer, and 2 parts by weight of a sorbitan fatty acid ester surfactant as a dispersant Mixed by, to prepare a slurry. The slurry was formed into a sheet shape by the doctor blade method, and the obtained formed body was dried at 70 ° C. for 5 hours to produce a flat green sheet having a square shape with a thickness of 150 μm and a side length of 65 mm.

  Next, a flat plate green sheet was punched into a shape shown in FIG. The ratio (area ratio) of the punched portion was 21.3%. Next, the punched green sheet and the flat green sheet were bonded together by a hot press. The obtained laminate was fired at 1300 ° C. for 2 hours to obtain an anode substrate of Example 1. In the anode substrate of Example 1, the thickness of the bank portion was 250 μm, and the thickness of the hollow portion was 125 μm.

(Examples 2 to 6)
Except for the point that the flat green sheet produced in Example 1 was punched into the shapes shown in FIGS. 6B to 6F, anode substrates of Examples 2 to 6 were produced in the same manner as in Example 1. Also in the anode substrates of Examples 2 to 6, the thickness of the bank portion was 250 μm, and the thickness of the recess portion was 125 μm.

(Reference example)
Two flat green sheets produced by the same method as in Example 1 were bonded together by hot pressing. The obtained laminate was fired under the same conditions as in Example 1 to obtain an anode substrate of a reference example.

[Compressive strength test]
The anode substrate was disposed between two alumina plates (Nikkato Corp., SSA-S) having a smooth surface and held parallel to each other. Using a material testing machine (Instron model 4301), apply a load to the upper alumina plate, gradually increase the load, and use the load when the anode substrate cracks (destructive load) as a measure of the mechanical strength of the anode substrate. Recorded as. The results are shown in Table 1.

  As shown in Table 1, the breaking load of Examples 1 to 4 with the ratio of the depressions of 14.8% to 32.8% is 3.0 kN to 3.2 kN, and the breaking load of the reference example (3.3 kN) ). That is, an anode substrate having a strength equivalent to that of a conventional substrate (a substrate having a high strength per unit weight) can be manufactured with a small amount of material.

DESCRIPTION OF SYMBOLS 10 Anode 12 Solid electrolyte layer 14 Cathode 16, 50, 60, 70 Anode substrate 16p First main surface 16q Second main surface 18 Anode active layer 20 First separator 20a Fuel gas supply groove 22 Second separator 22a Oxidant gas supply groove 24 Power generation element 30, 40 Embankment 32, 42, 44, 46 Recess 100 Solid oxide fuel cell 160 Flat green sheet (first ceramic green sheet)
161 Punched green sheet (second ceramic green sheet)
162 Laminate

Claims (9)

An anode substrate for supporting a solid electrolyte layer of a solid oxide fuel cell,
The first main surface,
A undulating second main surface,
A bank portion to be in contact with a separator of the fuel cell;
And a hollow portion formed thinner than the bank portion,
The anode substrate has a flat plate shape as a whole,
The first main surface is formed by the surface of the bank portion and the surface of the recess portion being on the same plane,
The anode substrate, wherein the undulations of the second main surface are formed due to a difference in thickness between the bank portion and the recess portion.   The anode substrate according to claim 1, wherein the undulations of the second main surface show a regular pattern.   The anode substrate according to claim 1 or 2, wherein the bank portion includes a frame-shaped portion formed along an outer edge of the anode substrate.   The thickness d of the dent is adjusted so as to satisfy a relationship of 0.3D <d <D, where D is the thickness of the bank and d is the thickness of the dent. The anode substrate according to any one of -3.   5. The proportion of the recess in the anode substrate is 35% or less in terms of a surface area observed when the second main surface is viewed in plan. Anode substrate.   The anode substrate according to claim 1, wherein the anode substrate is made of a porous ceramic containing nickel oxide and zirconia. The anode substrate according to any one of claims 1 to 6,
A cathode,
A solid electrolyte layer disposed between the anode substrate and the cathode;
A solid oxide fuel cell comprising: A first separator configured to supply fuel gas to the anode substrate;
A second separator configured to supply an oxidant gas to the cathode;
Further comprising
The first separator is formed with a fuel gas supply groove for supplying the fuel gas to the anode substrate,
The first separator is in surface contact with the bank portion of the anode substrate;
8. The solid oxide fuel according to claim 7, wherein the fuel gas supply groove communicates with the depression so that the fuel gas is guided from the fuel gas supply groove to the depression of the anode substrate. battery. A method for manufacturing an anode substrate for supporting a solid electrolyte layer of a solid oxide fuel cell, comprising:
Preparing a flat first ceramic green sheet;
Preparing a second ceramic green sheet having an opening;
Bonding the first ceramic green sheet and the second ceramic green sheet to each other so that a laminate of the first ceramic green and the second ceramic green sheet is formed;
Firing the laminate;
A method for manufacturing an anode substrate, comprising:

Images