JP2012209152A - Method for manufacturing anode support type solid oxide fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing solid oxide fuel cell, which can easily manufacture anode support type solid oxide fuel cell in which an anode is thicker than a cathode and an electrolyte membrane.SOLUTION: The manufacturing method includes: a step for preparing a mixture obtained by mixing a binder formed by a low melting point organic substance and a powder material for an anode and a molding mask 4 having a through aperture 40 when forming an anode 6; a step for molding a green-state anode 6 on the surface of an electrolyte membrane 2 by heating the mixture to a temperature equal to or higher than a melting point of the low melting point organic substance included in the mixture to turn the low melting point organic substance to a liquid phase and turn the mixture to a fluid material 100, and further allowing the fluid material 100 to flow into the through aperture 40 of the molding mask 4 formed on the surface of the electrolyte membrane 2 and solidifying the fluid material 100; and a step for forming the anode 6 on the surface of the electrolyte membrane 2 by firing at least the green-state anode 6 in a firing temperature area.

Description

  The present invention relates to a method for producing an anode-supported solid oxide fuel cell.

  A solid oxide fuel cell is provided. The solid oxide fuel cell has a cathode, a solid oxide electrolyte membrane, and an anode in the thickness direction. In recent years, anode-supported fuel cells having a structure in which the thickness of the anode is considerably thicker than the electrolyte membrane and the cathode have been provided. According to this structure, since the anode is thick, the thickness of the electrolyte membrane can be reduced, which can contribute to increasing the oxygen ion conductivity in the thickness direction of the electrolyte membrane.

  In manufacturing the anode described above, Patent Document 1 uses general screen printing. Patent Document 2 uses a doctor blade method. Patent documents 3 and 4 use a general press molding method.

JP 2009-140730 A JP 2009-199994 A JP 2007-311318 A JP 2008-66296 A

  According to Patent Document 1, although screen printing is advantageous for thin film molding, it is not preferable for forming a thick anode. According to Patent Document 2, the doctor blade method is adopted, but it is not preferable for forming a thick anode. Further, a large amount of solvent is used to make the raw material slurry into a slurry. However, when the molded anode is dried before firing, cracks may be generated in the anode as the solvent evaporates. In order to avoid this, there is a problem of requiring a long drying process under controlled atmosphere, and the productivity is lowered. Patent Documents 3 and 4 require a step of granulating the raw material in order to improve the mold filling property of the raw material into the press die. Furthermore, when considering mold filling properties, there is a limit to the improvement in the strength of the anode, and there is a possibility that cracks are likely to be generated in the anode during handling. Furthermore, in press molding, an increase in the capacity of an expensive press machine is inevitable as the cell size increases.

  The present invention has been made in view of the above circumstances, and it is easy to provide an anode-supported solid oxide fuel cell in which the thickness of the anode is larger than the thickness of the cathode and the thickness of the electrolyte membrane while suppressing the occurrence of cracks. It is an object of the present invention to provide a method for producing an anode-supported solid oxide fuel cell that can be produced easily.

  A method for producing an anode-supported solid oxide fuel cell according to the first aspect of the present invention includes a cathode, a solid oxide electrolyte membrane, and an anode thicker than the cathode and the electrolyte membrane, A method of manufacturing a solid oxide fuel cell in which an electrolyte membrane is sandwiched between a cathode and an anode. In forming the anode, (i) a binder formed of a low-melting-point organic substance and an anode powder material A step of preparing a mixed mixture and a molding mask having a through-opening; and (ii) heating the mixture to a temperature higher than the melting point of the low-melting-point organic substance contained in the mixture to make the low-melting-point organic substance into a liquid phase, And forming a green anode on the surface of the electrolyte membrane by allowing the fluid to flow into a through-opening of a molding mask placed on the surface of the electrolyte membrane and solidifying it. , And a step of forming on the (iii) by baking at the anode the firing temperature region of at least the green state, the surface of the anode electrolyte membrane. The green state refers to an unfired state although it is molded as a generated shape.

  According to this aspect, since the thickness of the anode is thicker than the thickness of the cathode and the thickness of the electrolyte membrane, the electrolyte membrane has high retention, the thickness of the electrolyte membrane can be reduced, and the oxygen ion conductivity in the thickness direction of the electrolyte membrane can be reduced. Can contribute to increase.

  According to this aspect, the mixture that becomes the green anode includes a binder formed of a thermoplastic low-melting-point organic substance instead of the solvent. For this reason, if a mixture is heated more than the melting | fusing point of the low melting-point organic substance contained in a mixture, a low-melting-point organic substance can be made into a liquid phase and a mixture can be made into a fluid. The melting point of the low melting point organic material may be higher than room temperature, and can be 200 ° C. or lower, 150 ° C. or lower, and further 100 ° C. or lower, 90 ° C. or lower. Furthermore, a green state anode can be formed on the surface of the electrolyte membrane by allowing a fluid to flow into a through-opening of a molding mask placed on the surface of the electrolyte membrane and solidifying the fluid. According to this aspect, when the low-melting-point organic substance is converted into a liquid phase, the fluid exhibits fluidity, so that the filling property of filling the fluid into the through-opening of the molding mask can be improved. In addition, since a molding mask having a through-opening is used, the thickness of the green anode can be increased according to the thickness of the molding mask. Since the low-melting-point organic substance in liquid phase is solidified with the subsequent cooling, the strength of the green-state anode is ensured even when the thickness of the green-state anode is thick, and the shape of the green-state anode is maintained. Sex is maintained. Solidification can be performed by cooling after mask formation or standing at room temperature.

  According to this aspect, although the low-melting-point organic substance is made into a liquid phase, a solvent that evaporates even in the normal temperature region is not used. For this reason, in the state where the formed green state anode is held or stored, the evaporation of the solvent from the green state anode after molding and before firing is suppressed. Therefore, in the state where the green state anode is held or stored after molding and before firing, it is possible to prevent cracks due to solvent evaporation from occurring in the green state anode or deformation of the anode. Furthermore, damage to the green anode due to drying shrinkage can be suppressed. If such a green anode is fired in a firing temperature region in a firing atmosphere, the fired anode can be satisfactorily formed. Furthermore, unlike tape molding, even when the anode in the green state is made thicker, the excessive flow of the material can be suppressed and the anode in the green state can be molded into a desired shape, so that material loss can be suppressed. In addition, even when the fluid that has heated the mixture does not flow into the through-opening of the molding mask and remains, if the excessively solidified mixture is heated again above the melting point of the low-melting organic material, the mixture and the flow Animals can be reused.

  According to the method for producing a solid oxide fuel cell according to aspect 2 of the present invention, in the above aspect, the melting point of the low-melting-point organic substance is in the range of 40 to 90 ° C. The operation of aspect 1 described above can be easily realized.

  According to the method of the present invention, a fluid is allowed to flow into a through-opening of a molding mask placed on the surface of the electrolyte membrane to form a green anode on the surface of the electrolyte membrane. As the low-melting-point organic substance in liquid phase is rapidly solidified with cooling, the strength and shape retention of the green anode can be maintained even when the green anode is thick.

According to the method of the present invention, since the solvent that evaporates even in the normal temperature region is not used, the evaporation of the solvent from the green state anode can be suppressed while the molded green state anode is held or stored. Therefore, in a state where the green state anode is held or stored before firing, it is possible to suppress the occurrence of cracks due to the evaporation of the solvent in the green state before firing. If such a green state anode is fired in the firing temperature range, the fired anode can be satisfactorily formed.
Can provide.

It is a figure which concerns on Embodiment 1 and shows the concept of a manufacturing process typically. It is a figure which concerns on Embodiment 2 and shows the concept of a manufacturing process typically.

  The solid oxide fuel cell is an anode-supported flat cell and is fired. Since the anode is thick and constitutes a fuel cell support, the thickness of the electrolyte membrane having oxygen ion conductivity can be reduced, which is advantageous for increasing the ionic conductivity in the thickness direction of the electrolyte membrane. An anode-supported flat cell has a cathode, a solid oxide electrolyte membrane, and an anode that is thicker than the cathode and electrolyte membrane. The electrolyte membrane is sandwiched between the cathode and the anode. Examples of the cathode include perovskite oxides, and specific examples include lanthanum manganite, lanthanum ferrite, lanthanum cobaltite, strontium cobaltite, and lanthanum nickel.

In forming the anode, a step of preparing a mixture obtained by mixing a binder formed of a low-melting-point organic material and an anode powder material and a molding mask having a through opening is performed. The low melting point organic substance contained in the mixture is made into a liquid phase so that the mixture has fluidity. The reason for making the liquid phase is to efficiently flow into the through-opening of the molding mask and improve the filling property of the fluid. Examples of the powder material for the anode include mixed powders and composite powders containing a stabilized zirconia system and / or a doped ceria system (for example, GDC, SDC, LDC, etc.). The anode powder material may include a metal oxide. An example of the metal oxide is nickel oxide. In this case, when the anode powder material is 100%, the mass ratio of the stabilized zirconia system containing the stabilizer is 30 to 50%, and the catalyst metal oxide (such as nickel oxide) is 70 to 50%. Can be. Examples of the stabilizer include at least one of yttria (Y ₂ O ₃ ), calcia (CaO), magnesia (MgO), ceria (CeO ₂ ), and scandia (Sc ₂ O ₃ ). Stabilizers include, but are not limited to, a molar ratio of 0.1 to 15%, 0.2 to 13%, and 0.5 to 10%.

  The reason for using a shaped mask with a through opening is that mask printing is preferred over screen printing because the thickness of the anode is much thicker than the electrolyte membrane and cathode. The thickness of the anode is 5 to 200 times or 10 to 100 times the thickness of the electrolyte membrane. This is advantageous in reducing the thickness of the electrolyte membrane. Since the thickness of the molding mask corresponds to the thickness of the anode, the thickness of the anode can be adjusted by adjusting the thickness of the molding mask. The melting point of the low-melting organic substance is preferably 30 to 150 ° C, 40 to 90 ° C, and 50 to 80 ° C. Examples of the upper limit of the melting point include 120 ° C., 90 ° C., 85 ° C., and 80 ° C. The lower limit of the melting point that can be combined with the upper limit is only required to be higher than room temperature, and any of 40 ° C., 45 ° C., and 50 ° C. can be exemplified. The melting point can be defined as a temperature at which generation of a liquid phase is started by increasing the temperature when there is a range of melting point temperatures.

The low melting point organic substance preferably has the following properties.
(1) It is preferably made of carbon, oxygen, hydrogen, nitrogen, etc., has good thermal decomposability, and does not contain metal, sulfur, or halogen.
(2) The melting point of the low melting point organic substance is preferably 50 to 90 ° C.
(3) Regarding the volatility of the low-melting-point organic substance, it is preferable that there is no significant volatility from room temperature to near the melting point. This is in order to suppress cracks in the green anode.
(4) Regarding the crystallinity of the low-melting-point organic substance, it is preferable not to crystallize during solidification.
(5) Regarding the dispersibility of the low melting point organic substance, it is preferable that the anode powder material is not unevenly distributed even if the binder is in a liquid phase state or a solidified state.
(6) Regarding the viscosity of the low melting point organic substance, it is preferable that there is no phenomenon such as stringing in the liquid phase in consideration of mask printing.
(7) Regarding the expansion / contraction property of the low-melting-point organic substance, it is preferable that the volume change is small during the phase transition between the liquid phase and the solid phase.
(8) It is preferable that adhesiveness with an electrolyte membrane can be improved by having polar groups such as a hydroxyl group, a carboxyl group, an ether group, and an ester group.

  Examples of the low-melting-point organic substance that serves as the binder include polymers, linear hydrocarbons, esters, higher alcohols, fatty acids, and mixed systems. The melting point is preferably in the range of 40 to 90 ° C. If the melting point is too low, it will not solidify at room temperature and the shape cannot be maintained. If the melting point is too high, the melting temperature will be high and a large-scale heating / warming mechanism will be required. When the melting point width exists, the melting point can be a temperature at which liquefaction starts as the temperature rises. Examples of the polymer include polyethylene glycol. Examples of the polyethylene glycol include polyethylene glycol 2000 (melting point: 45 to 55 ° C.), polyethylene glycol 1000 (melting point: 30 to 40 ° C.), and polyethylene glycol 6000 (melting point: 50 to 65 ° C.). Numbers such as 2000 mean average molecular weight. Examples of the linear hydrocarbon include paraffin (melting point: 56 to 58 ° C.). Examples of the ester include beeswax (melting point: 60 to 66 ° C.). Examples of the higher alcohol include hexadecanol (1-hexadecanol (melting point: 49 to 53 ° C.)) and octadecanol (1-octadecanol (melting point: 57 to 60 ° C.)). Examples of fatty acids include hydroxystearic acid (12-hydroxystearic acid (melting point: 74 to 79 ° C)), myristic acid (melting point: 53 to 56 ° C), palmitic acid (melting point: 60 to 63 ° C), and stearic acid (melting point: 56). ~ 72 ° C). The mixed system of low melting point organic substances is a mixture of a plurality of low melting point organic substances. Examples of the mixed system of low melting point organic materials include a material in which beeswax (melting point: 60 to 66 ° C.) and paraffin (melting point: 56 to 58 ° C.) are mixed. In this case, the mixing ratio of beeswax and paraffin can be set as appropriate. By mass ratio, beeswax: paraffin = (1-5): 1. For example, beeswax: paraffin = 3: 1.

  According to the method of the present invention, the mixture is heated to a temperature equal to or higher than the melting point of the low-melting-point organic substance contained in the mixture, and the low-melting-point organic substance is liquid-phased to make the mixture a fluid. Further, a fluid is caused to flow into a through-opening of a molding mask installed on the surface of the electrolyte membrane, thereby forming a green anode on the surface of the electrolyte membrane. Green means an unfired formed form. When the mixture is heated above the melting point of the low-melting organic substance, the molding mask has heat resistance so that the molding mask does not deform excessively or become soft. Considering heat resistance, the mask is preferably a metal mask or a ceramic mask rather than a resin mask. Depending on the case, it is good also as a mask shape | molded with resin whose heat resistance is higher than melting | fusing point of a low melting-point organic substance.

  Furthermore, a step of forming the anode on the surface of the electrolyte membrane is performed by firing at least the green anode in the firing temperature region. The low melting point organic substance is removed from the anode by the heating at the time of firing. By controlling the heating, the low melting point organic substance can be removed well from the anode. Firing may be performed in a single firing step, or a plurality of firing steps may be performed. That is, the preliminary baking and the main baking may be performed continuously, or the preliminary baking and the main baking may be separately performed in a discontinuous state. The firing temperature range varies depending on the material of the anode in the green state, but generally 1000 to 1500 ° C and 1100 to 1400 ° C are exemplified. An example of the firing atmosphere is an oxidizing atmosphere. The oxidizing atmosphere is a gas atmosphere containing oxygen, and may be an air atmosphere, an oxygen-enriched atmosphere, or a mixed gas atmosphere of an inert gas and oxygen, and the low-melting-point organic substance used as the binder is decomposed and solidified. It is an atmosphere in which no object remains or hardly remains.

(Embodiment 1)
FIG. 1 schematically shows the first embodiment. According to the present embodiment, as shown in FIG. 1A, it is installed on a release film 53 (for example, a PET film) on the installation surface 50u of the table 50, and is in a green state on the film 53. A green state laminate 3 having a two-layer structure including a reaction preventing layer 1 (thickness: tr) and a green state electrolyte membrane 2 (thickness: te) is formed. In addition, a mixture in which a binder formed of a low melting point organic material and an anode powder material are mixed is prepared in advance. Similarly, a metal mask 4 (material: aluminum, molding mask) having a through opening 40 penetrating in the thickness direction is prepared in advance. The upper surface 4u and the lower surface 4d of the metal mask 4 are flat surfaces. The thickness tm of the metal mask 4 is set to be thicker than the thickness tr of the green reaction preventing layer 1 and the thickness te of the electrolyte membrane 2 in the green state, for example, 0.5 to 3 millimeters, 0.5 to 2 millimeters. However, the present invention is not limited to this. As the low melting point organic substance, at least one of the above-described low melting point organic substances can be used. That is, at least one of polyethylene glycol, paraffin, beeswax, higher alcohol (1-hexadecanol, 1-octadecanol, hydroxystearic acid, myristic acid, palmitic acid, and stearic acid can be used. If a plurality of low melting point organic substances are mixed, the melting point of the low melting point organic substance can be adjusted, and it can be expected that the fluidity of the fluid can be adjusted.

Examples of the powder material for the anode include a stabilized zirconia-based material containing a stabilizer, and further includes a metal compound (oxide) such as nickel serving as a catalyst. At least one of the above-mentioned stabilizers (yttria (Y ₂ O ₃ ), calcia (CaO), magnesia (MgO), ceria (CeO ₂ ), scandia (Sc ₂ O ₃ ), etc.) in the above proportion. The zirconia powder containing is mentioned.

  In the above-mentioned mixture, when the mixture is 100%, the anode powder material (including nickel oxide and the like serving as the anode catalyst) is preferably 70 to 95%, particularly 80 to 90%, and the low melting point organic substance. The binder formed by 5 to 30%, especially 10 to 20% is preferable.

  Next, as shown in FIG. 1B, the metal mask 4 is placed in contact with the surface of the green electrolyte membrane 2. Then, the squeegee 55 (scraping member) is laterally moved in a state where the mixture is heated by a heating element in a temperature region Tw (within a range of Tw = 45 to 90 ° C.) of the low melting point organic substance contained in the mixture. Move along (arrow H direction). As a result, a fluid is caused to flow into the through-opening 40 of the metal mask 4 and placed on the electrolyte membrane 2 in the green state to form the anode 6 in the green state. Here, when the melting point of the low-melting-point organic substance is Tm, the heating temperature T of the mixture is T = Tm + ΔT. ΔT can be appropriately set, but is preferably 5 to 20 ° C. When ΔT is high, Tw becomes high, and heating and heat retention become large. When ΔT is low, partial solidification due to temperature variation becomes a problem.

  The heating timing for heating the mixture may be before the metal mask 4 is placed on the surface of the electrolyte membrane 2 in the green state, or after the metal mask 4 is placed on the surface of the electrolyte membrane 2 in the green state. Alternatively, the metal mask 4 may be installed on the surface of the electrolyte membrane 2 in the green state. Any heating element can be used as long as it can be heated to a temperature range equal to or higher than the melting point Tm of the low-melting-point organic substance contained in the mixture. You may carry out by heating at least one of the squeegee 55 and the metal mask 4 to the temperature range more than melting | fusing point Tm. You may decide to implement the above-mentioned operation in a heating furnace. As a result, the low melting point organic substance is made into a liquid phase and the mixture is made into the fluid 100.

  As described above, 100 of the fluid is caused to flow into the through opening 40 of the molding mask 4. Along with the subsequent cooling, the temperature becomes lower than the melting point Tm of the low-melting organic substance, so that the fluid 100 in the through opening 40 of the metal mask 4 is solidified. As a result, the green anode 6 is formed on the surface of the green electrolyte membrane 2 (electrolyte membrane) (see FIG. 1C). Depending on the thickness of the metal mask 4, that is, the depth of the through-opening 40, the thickness of the anode 6 in the green state, and thus the thickness of the anode 6 after sintering can be controlled.

  Thereafter, before the solidification of the anode 6 in the green state proceeds, the molding mask 4 is removed from the anode 6 on the electrolyte membrane 2 and the excess portion is cut off. In this case, although the fluid 100 contains a low-melting-point organic substance that solidifies upon cooling, it does not contain a solvent that easily evaporates even in the normal temperature region. Therefore, even if the anode 6 in the green state is thick, The anode 6 has high strength and shape retention. Furthermore, although the fluid 100 has fluidity, it does not contain a solvent and there is no evaporation of the solvent in the room temperature region, so that the generation of cracks before firing is suppressed in the green-state anode 6.

  As a result, a green laminate 8 having a three-layer structure is formed (see FIG. 1D). As shown in FIGS. 1C and 1D, the green state laminate 8 includes a green state reaction preventing layer 1, a green state electrolyte membrane 2, and a green state anode in order in the thickness direction. 6 and.

  The thickness ta of the green-state anode 6 is larger than the thickness tr of the green-state reaction prevention layer 1 and the thickness te of the electrolyte membrane 2 in the green state. For example, the thickness ta of the anode 6 in the green state can be 200 to 2000 micrometers, in particular 400 to 700 micrometers. The thickness tr of the reaction preventing layer 1 in the green state can be 5 to 40 micrometers, in particular 10 to 20 micrometers. The thickness te of the electrolyte membrane 2 in the green state can be 5 to 40 micrometers, particularly 10 to 20 micrometers. A range of ta / te = 10 to 400, in particular a range of 20 to 100, can be mentioned. However, it is not limited to these.

  Next, the laminated body 8 in the green state is integrally fired in a firing temperature region (1300 to 1400 ° C.) in an air atmosphere (oxidizing atmosphere) firing furnace. Thereby, the fired laminated body 9 having a three-layer structure is formed (see FIG. 1E). As shown in FIG. 1E, the fired laminate 9 has a fired reaction preventing layer 1, a fired electrolyte film 2, and a fired anode 6 in this order in the thickness direction. The fired anode 6 is thicker than the fired reaction preventing layer 1 and the fired electrolyte membrane 2. Thereafter, a green cathode 7 is formed on the opposite side of the fired laminate 9 from the anode 6 and fired integrally in an air atmosphere. Thereby, the fuel cell 10 is formed ((F) of FIG. 1). Note that the cell 10 is reduced by a power generation operation in which hydrogen gas (hydrogen-containing gas) is supplied as the anode gas.

  As described above, according to the present embodiment, the mixture that becomes the green anode 6 includes a binder formed of a low-melting-point organic substance instead of the solvent that evaporates even in the normal temperature region. For this reason, if a mixture is heated more than melting | fusing point of the low melting-point organic substance contained in a mixture, a low-melting-point organic substance can be made into a liquid phase and the mixture can be made into the fluid 100. Furthermore, the green material anode 6 can be formed on the surface of the electrolyte membrane 2 by flowing the fluid 100 into the through opening 40 of the metal mask 4 installed on the surface of the electrolyte membrane 2. With cooling, the low-melting-point organic substance that has been made into a liquid phase solidifies, so that the strength and shape retention of the green-state anode 6 can be maintained. According to such this embodiment, the fluidized part 100 does not contain a solvent. Therefore, in the state where the molded green state anode 6 is held or stored before firing, the evaporation of the solvent from the green state anode 6 can be suppressed. Therefore, in a state where the green state anode 6 is held or stored before firing, it is possible to suppress the occurrence of cracks due to the evaporation of the solvent in the green state before firing. If such a green state anode 6 is fired in an air atmosphere at a firing temperature range (temperature: 1300 to 1400 ° C., time: 2 to 5 hours, for example), the fired anode 6 can be formed satisfactorily. The fired anode 6 is a porous body having a large number of pores formed by removing low melting point organic substances. The pores in the fired anode 6 can be controlled by the blending form of the low melting point organic substance.

(Embodiment 2)
FIG. 2 schematically shows the second embodiment. According to the present embodiment, as shown in FIG. 2A, the electrolyte membrane 2 in a green state (thickness: te2) is formed. In addition, a mixture is prepared in which a binder formed of a low-melting-point organic substance and an anode powder material are mixed. Similarly, a metal mask 4 (material: aluminum, molding mask) having a through opening 40 is prepared. As the low-melting-point organic material, the anode powder material, and the mixture obtained by mixing them, the same materials as those in Embodiment 1 are used.

  Next, as shown in FIG. 2A, the electrolyte membrane 2 in a green state is formed on the release film 53 installed on the installation surface 50 u of the table 50. Next, as shown in FIG. 2B, a metal mask 4 is placed on the surface of the electrolyte membrane 2 in a green state. Then, the squeegee 55 (scraping member) is moved in a state where the mixture is heated by a heating element to a temperature region Tw (Tw = for example, within a range of 45 to 90 ° C.) above the melting point Tm of the low melting point organic substance contained in the mixture. Let As a result, the fluid 100 flows into the through-opening 40 of the metal mask 4 and is placed on the green electrolyte membrane 2 to form the green-state anode 6. Here, when the melting point of the low-melting-point organic substance is Tm, the heating temperature T of the mixture is T = Tm + ΔT. ΔT can be appropriately set, but is preferably 5 to 20 ° C. As before, the heating timing may be before the metal mask 4 is placed on the surface of the electrolyte membrane 2 in the green state, or after the metal mask 4 is placed on the surface of the electrolyte membrane 2 in the green state. Alternatively, the metal mask 4 may be installed on the surface of the electrolyte membrane 2 in the green state. Any heating element can be used as long as it can be heated to a temperature range equal to or higher than the melting point Tm of the low-melting-point organic substance contained in the mixture. It may be carried out by heating at least one of the squeegee 50 and the metal mask 4 to a temperature range higher than the melting point Tm. As a result, the low melting point organic substance is made into a liquid phase and the mixture is made into the fluid 100.

  As described above, the fluid 100 is caused to flow into the through opening 40 of the metal mask 4. Along with the subsequent cooling, the temperature becomes lower than the melting point Tm of the low-melting organic substance, so that the fluid 100 in the through opening 40 of the metal mask 4 is solidified. When solidified, the metal mask 4 is removed. In this way, the green state anode 6 is formed on the surface of the green state electrolyte membrane 2 (see FIG. 2C). Thereafter, the surplus portion is cut. In this case, although the fluid 100 contains a low-melting-point organic substance that solidifies upon cooling, it does not contain a solvent that easily evaporates even in the normal temperature region, so the anode 6 in the green state has high strength and shape retention. Furthermore, since there is no evaporation of the solvent in the normal temperature region, the generation of cracks before firing is suppressed in the green-state anode 6. As a result, a green laminate 8 having a two-layer structure is formed.

  As shown in FIG. 2D, the green state laminate 8 has a green state electrolyte membrane 2 and a green state anode 6 (thickness: ta2) in order in the thickness direction. The anode 6 in the green state is considerably thicker than the thickness of the electrolyte membrane 2 in the green state. Next, the laminated body 8 in the green state is integrally fired in a firing temperature region (1300 to 1400 ° C.) in an air atmosphere (oxidizing atmosphere) firing furnace. As a result, a fired laminate 9 having a two-layer structure is formed (see FIG. 2E). As shown in FIG. 2E, the fired laminate 9 has a fired electrolyte membrane 2 and a fired anode 6 in order in the thickness direction. The fired anode 6 is thicker than the thickness of the fired electrolyte membrane 2. Next, the cathode 7 in a green state is formed on the surface of the baked electrolyte membrane 2 opposite to the anode 6 and fired integrally. Thereby, the fuel cell 10 having a three-layer structure is formed (see FIG. 2F).

  As described above, according to the present embodiment, the mixture that becomes the green anode 6 includes a binder formed of a low-melting-point organic substance instead of the solvent that evaporates even in the normal temperature region. For this reason, if a mixture is heated more than melting | fusing point of the low melting-point organic substance contained in a mixture, a low-melting-point organic substance can be made into a liquid phase and the mixture can be made into the fluid 100. Furthermore, the green material anode 6 can be formed on the surface of the electrolyte membrane 2 by flowing the fluid 100 into the through opening 40 of the metal mask 4 installed on the surface of the electrolyte membrane 2. With the subsequent cooling, the low-melting-point organic substance in liquid phase is solidified, so that the strength and shape retention of the green anode 6 are maintained. According to this embodiment, since no solvent is used, the evaporation of the solvent from the green state anode 6 can be suppressed in a state where the molded green state anode 6 is held or stored before firing. . Therefore, in the state where the green-state anode 6 is held or stored before firing, the occurrence of cracks due to the evaporation of the solvent can be suppressed in the green-state anode 6. If such a green state anode 6 is fired in an oxidizing atmosphere in a firing temperature range (temperature: for example, 1300 to 1400 ° C., time: for example, 2 to 5 hours), the fired anode 6 can be satisfactorily formed.

(Test Example 1)
Nickel oxide powder to be the anode catalyst and zirconia powder were mixed to obtain an anode powder material. That is, nickel oxide (NiO) and 8YSZ [(Y ₂ O ₃ ) _0.08 (ZrO ₂ ) _0.92 ] were mixed to obtain an anode powder material. Numbers indicate molar ratios. A low melting point organic substance (polyethylene glycol 2000, melting point 45 to 55 ° C.) was added thereto as a binder to form a mixture. When the mixture was 100%, the anode powder material was 84% and the low-melting-point organic substance was 16% by mass ratio.

  The above mixture is heated to 80 ° C. (above the melting point of the low melting point organic substance, the melting point of the low melting point organic substance plus a temperature of 25 to 35 ° C.) to melt the binder, and the mixture is stirred and degassed to form a slurry. A fluid was formed. Then, a metal mask, a table, and a squeegee having a through-opening are heated to 70 ° C., and the metal mask is placed on a film (PET) coated with a release agent. In this state, the squeegee is moved laterally along the metal mask, and the fluid is caused to flow into the through opening to perform metal mask printing. This formed a green anode on the film. Here, the thickness of the metal mask was 1 millimeter, and the diameter of the through opening was 43 millimeters. After printing the metal mask, the green anode was quickly cooled. This maintained the shape and strength of the green anode. In this case, an anode in a green state having a thickness of 1 mm was formed. The green anode was fired in an oxidizing atmosphere at 1300 ° C. for 5 hours to form a fired laminate. When the cross section of the fired anode was observed with an SEM, it was confirmed that a homogeneous internal structure was obtained. The anode after firing was a porous body having a large number of pores from which low melting point organic substances were removed.

(Test Example 2)
Test Example 2 will be described with reference to FIG. Nickel oxide powder to be the anode catalyst and zirconia powder were mixed to obtain an anode powder material. That is, nickel oxide (NiO) and 8YSZ [(Y ₂ O ₃ ) _0.08 (ZrO ₂ ) _0.92 ] were mixed to obtain an anode powder material. A low melting point organic substance (low melting point organic substance in a mixed system of beeswax and paraffin, melting point 70 ° C.) was added as a binder to form a mixture. In this case, assuming that the low melting point organic substance is 100%, beeswax is 12% and paraffin is 4%. In a state where the mixture was heated to 95 ° C. (above the melting point of the low-melting organic material) to melt the binder, the mixture was stirred and degassed to form a slurry-like fluid.

  Then, as shown in FIG. 2, a film 53 coated with a release agent in a state where the metal mask 4 having the through-opening 40, the table 50, and the squeegee 55 are heated to 90 ° C. (more than the melting point of the low-melting-point organic substance). The electrolyte membrane 2 was placed on (PET). With the metal mask 4 placed on the electrolyte membrane 2, the squeegee 55 was moved laterally along the metal mask 4. As a result, the fluid 100 was poured into the through opening 40 of the metal mask 4 to fill it, and metal mask printing was performed. Thereby, the anode 6 in a green state was laminated on the surface of the electrolyte membrane 2 (see FIG. 2C). Here, the thickness tm of the metal mask 4 was 1 millimeter, and the diameter d of the through opening 40 was 43 millimeters.

Here, regarding the above-described electrolyte membrane 2 in a green state, a commercially available 8YSZ powder [(Y ₂ O _{3) 0.08} (ZrO ₂ ) _0.92 ] is mixed with a solvent (ethanol) and a dispersant (Marialim, Nippon Oil & Fats. Co., Ltd.), a plasticizer (benzylbutyl phthalate), and a binder (polyvinyl butyral) were added and molded by the doctor blade method. The obtained two-layer laminate 8 in a green state in which the anode 6 and the electrolyte 2 were laminated was co-fired in an oxidizing atmosphere at 1300 ° C. × 5 hours to form a fired laminate 9. SEM observation of the cross section of the fired anode 9 after firing was confirmed, and it was confirmed that a homogeneous internal structure was obtained. The fired anode 6 was a porous body having a large number of pores from which low melting point organic substances were removed. The anode gas can flow into these pores.

On the fired laminated body 9 that this co-fired to form a slurry of the second fluids by adding polyethylene glycol 400 in a commercially available LSM powder _{(La 0.8 Sr 0.2 MnO 3)} . This second fluid was screen printed on the opposite side of the electrolyte membrane from the anode 6 to form the cathode 7 to form a laminate. This laminate was fired in an oxidizing atmosphere under predetermined firing conditions (1100 ° C. × 2 hours) to form anode-supported fuel cells 10. A power generation test was performed while hydrogen gas (anode gas) was supplied to the anode 6 of the fuel battery cell 10 thus formed and air (cathode gas) was supplied to the cathode 7. A maximum output of 0.20 W / cm ² was obtained at an operating temperature of 700 ° C. In the fuel cell 10, the thickness of the anode 6 after firing was 50 times the thickness of the electrolyte membrane 2 after firing.

(Test Example 3)
Test Example 3 will be described with reference to FIG. Test Example 3 is basically the same as Test Example 2. However, instead of the electrolyte membrane according to Test Example 2, a two-layer laminated sheet was used. The two-layer laminated sheet includes a reaction preventing layer 1 corresponding to the first layer and an electrolyte membrane 2 corresponding to the second layer (see FIG. 1A). The reaction preventing layer is GDC [(Gd ₂ O ₃ ) _X (CeO ₂ ) _1-X (X = 0.1 to 0.2)]. The electrolyte membrane is 8YSZ [(Y ₂ O ₃ ) _0.08 (ZrO ₂ ) _0.92 ]. Numbers refer to molar ratios.

  In Test Example 3, a laminate 8 in which the anode 6 was mask-printed on a two-layer laminate sheet was formed using the metal mask 4 having the through opening 40 ((D) in FIG. 1). The laminate was co-fired to form a fired laminate 9 ((E) in FIG. 1). The anode 6 after firing of the fired laminate 9 was observed by SEM, and a homogeneous internal structure was obtained. It was confirmed.

Thereafter, LSCF (La _0.6 Sr _0.4 Co _0.2 Fe _0.8 O ₃ ) was screen printed on the fired laminate 9 and fired as the cathode 7 to form the fuel cell 10 (see FIG. 1 (F)). A power generation test was performed while hydrogen gas (anode gas) was supplied to the anode 6 of the fuel battery cell 10 thus formed and air (cathode gas) was supplied to the cathode 7. A maximum output of 0.47 W / cm ² was obtained at an operating temperature of 700 ° C. In the fuel cell 10, the thickness of the anode 6 after firing was 50 times the thickness of the electrolyte membrane 2 after firing.

(Other)
The present invention is not limited to the embodiments described above and shown in the drawings, and can be implemented with appropriate modifications within the scope not departing from the gist. The metal mask 4 is not particularly limited to the number and shape of the through openings 40 and can be appropriately selected. The material of the molding mask is not limited to metal. In the anode-supported fuel cell in which the anode according to the present invention is a supporting substrate, the thickness of the anode after firing is thicker than the electrolyte membrane and the cathode after firing, for example, the thickness of the electrolyte membrane after firing. 3 to 300 times the range, and 5 to 200 times the range.

  1 is a reaction preventing layer, 2 is an electrolyte membrane, 3 is a laminate, 4 is a metal mask (molded mask), 40 is a through opening, 50 is a table, 53 is a film, 55 is a squeegee, 6 is an anode, 7 is a cathode, 8 is a laminate, 9 is a fired laminate, and 10 is a fuel cell.

Claims (2)

An anode-supported solid having a cathode, a solid oxide electrolyte membrane, and an anode thicker than the cathode and the electrolyte membrane, and laminated such that the electrolyte membrane is sandwiched between the cathode and the anode A method for manufacturing an oxide fuel cell, comprising:
In forming the anode,
Preparing a mixture of a binder formed of a low-melting-point organic material and a powder material for an anode, and a molding mask having a through-opening;
The molding mask disposed on the surface of the electrolyte membrane further comprises heating the mixture to a temperature higher than the melting point of the low-melting-point organic substance contained in the mixture to make the low-melting-point organic substance into a liquid phase, and turning the mixture into a fluid. Forming the anode in a green state on the surface of the electrolyte membrane by allowing the fluid to flow into the through-opening and solidifying the fluid;
A method of manufacturing an anode-supported solid oxide fuel cell, comprising: firing the anode in a green state at a firing temperature range to form the anode on a surface of the electrolyte membrane.   The method for producing an anode-supported solid oxide fuel cell according to claim 1, wherein the low-melting-point organic substance has a melting point in the range of 40 to 90 ° C.

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