JP2010199055A - Solid oxide fuel battery cell, method for manufacturing the same, fuel battery cell stack device, fuel battery module, and fuel battery device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solid oxide fuel battery cell capable of suppressing formation of lanthanum zirconate and a method for manufacturing the same, and to provide a fuel battery cell stack device, a fuel battery module and a fuel battery device. <P>SOLUTION: The solid oxide fuel battery cell 10 includes: a conductive support 1 having a fuel gas passage 2 therein through which fuel gas flows; an interconnector 8 formed on the conductive support 1 through an adhesion layer 7 and containing a lanthanum chromite base perovskite composite oxide; and a power generating element A formed by laminating a fuel electrode layer 3, a solid electrolyte layer 4, and an air electrode layer 6 in order, arranged on a portion in which the interconnector 8 is not formed of the conductive support 1. The adhesion layer 7 contains zirconia having 45 mole% or more rare earth element as a solid solution. High conductivity between the interconnector 8 and the conductive support 1 is kept and power generation efficiency of the cell 10 of the solid oxide fuel cell can be kept. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention provides a conductive support, an interconnector containing lanthanum chromite provided on the conductive support via an adhesion layer, and a portion of the conductive support where the interconnector is not provided. A solid oxide fuel cell comprising the power generation element provided, a method for producing the same, and a fuel cell stack device in which the solid oxide fuel cells are electrically connected in series via a current collector; The present invention relates to a fuel cell module in which the fuel cell stack device is stored in a storage container, and a fuel cell device in which the fuel cell module and an auxiliary device are stored in an outer case.

  In recent years, a fuel cell stack device in which a plurality of solid oxide fuel cells are electrically connected in series is connected to a fuel cell module housed in a storage container, or a fuel cell module housed in an outer case. Various fuel cell devices have been proposed.

  As such a solid oxide fuel cell, it has a pair of flat surfaces parallel to each other, has a fuel gas passage for allowing fuel gas to flow inside, and one of the conductive supports containing Ni. A solid oxide fuel cell comprising a fuel electrode layer, a solid electrolyte layer, and an air electrode layer laminated in this order on a flat surface on the side, and an interconnector containing lanthanum chromite on the flat surface on the other side Has been proposed (see, for example, Patent Document 1).

  There has been proposed a fuel cell stack device in which a plurality of such solid oxide fuel cells are electrically connected in series via a current collecting member (see, for example, Patent Document 2).

A fuel cell in which an interconnector containing lanthanum chromite is formed on a conductive support through an adhesion layer is known in order to make the coefficient of thermal expansion between the conductive support and the interconnector closer. In the adhesion layer of this fuel cell, at least one element selected from the group consisting of Y, Lu, Yb, Tm, Er, Ho, Dy, Gd, Sm, and Pr was dissolved in 8 mol%. those composed of ZrO ₂ and Ni are known (see Patent Document 3).

  In Patent Document 3, due to the adhesion layer between the interconnector and the conductive support, mutual diffusion of La and rare earth elements between the two during simultaneous firing can be suppressed, and the potential between the conductive support and the interconnector can be suppressed. It is stated that the descent can be reduced.

JP 2008-84716 A JP 2008-135304 A JP 2004-253376 A

However, in the fuel cell described in Patent Document 3, when the fuel cell is manufactured, when firing at a high temperature of about 1500 ° C., an electrically insulating lanthanum zirconate (La ₂ ) is formed at the interface between the interconnector and the adhesion layer. Zr ₂ O ₇ ) can be suppressed, but when fired at a low temperature of 1450 ° C. or lower, electrically insulating lanthanum zirconate is generated at the interface between the interconnector and the adhesion layer, and the conductive support There was a problem that the electrical conductivity between the body and the interconnector was lowered.

When firing at a low temperature of 1450 ° C. or lower, the reason why an electrically insulating lanthanum zirconate is formed at the interface between the interconnector and the adhesion layer is not clear, but when firing at a high temperature, La becomes an adhesion layer. Evenly diffused, La is dissolved in ZrO ₂ , and lanthanum zirconate is difficult to be produced, but when fired at low temperature, La does not diffuse so much, and the portion on the interconnector side of the adhesion layer It is believed that a large amount of lanthanum zirconate is produced without La being completely dissolved in ZrO ₂ .

  The present invention relates to a solid oxide fuel cell that can suppress the formation of lanthanum zirconate at the interface between an interconnector and an adhesion layer, a method for producing the same, and a fuel cell stack device, a fuel cell module, and a fuel cell device. The purpose is to provide.

  A solid oxide fuel cell according to the present invention includes a conductive support having a fuel gas passage for allowing a fuel gas to flow therein, and a lanthanum provided on the conductive support via an adhesion layer. An interconnector containing a chromite-based perovskite complex oxide and a fuel electrode layer, a solid electrolyte layer, and an air electrode layer, which are provided on the conductive support in a portion where the interconnector is not provided, are sequentially laminated. A solid oxide fuel cell comprising the power generating element, wherein the adhesion layer contains zirconia in which 45 mol% or more of a rare earth element is dissolved.

  In such a solid oxide fuel cell, the adhesion layer contains zirconia in which a rare earth element of 45 mol% or more is dissolved, so that lanthanum (La) in the interconnector is prevented from diffusing to the adhesion layer side. can do. The reason why the diffusion of La to the adhesion layer side in the interconnector can be suppressed is not clear, but zirconia present in the entire adhesion layer contains 45 mol% or more of a rare earth element. This is because the amount of the rare earth element that can be dissolved in the metal is small, and La, which is a component of the interconnector, is difficult to diffuse to the adhesion layer side.

  Thereby, it can suppress that La which is a structural component of an interconnector, and Zr which is a structural component of an adhesion | attachment layer can suppress, and it suppresses the production | generation of the lanthanum zirconate between an interconnector and an adhesion | attachment layer during electric power generation. It is possible to suppress deterioration with time of power generation efficiency, maintain high conductivity between the interconnector and the conductive support, and maintain high power generation efficiency of the solid oxide fuel cell.

  The solid oxide fuel cell of the present invention is characterized in that the adhesion layer does not contain lanthanum (La) at a depth of 1 μm from the interface with the interconnector. In such a solid oxide fuel cell, generation of lanthanum zirconate between the interconnector and the adhesion layer can be further suppressed.

  In the method for producing a solid oxide fuel cell according to the present invention, an adhesion layer molded body containing zirconia in which a rare earth element is dissolved in an amount of 45 mol% or more is provided on a conductive support molded body having a through-hole. An interconnector molded body containing an oxide powder containing lanthanum (La) and chromium (Cr) is provided on the adhesion layer molded body, and the conductive support in a portion where the interconnector molded body is not provided A step of producing a laminated molded body in which a fuel electrode layer molded body is provided on the molded body, and a solid electrolyte layer molded body is provided on the fuel electrode layer molded body; a step of firing the laminated molded body; And a step of forming an air electrode layer on the solid electrolyte layer formed by sintering the solid electrolyte layer formed body.

  In such a method for producing a solid oxide fuel cell, since zirconia in the adhesion layer molded body has a rare earth element dissolved in an amount of 45 mol% or more, there is little room for the rare earth element to dissolve in the zirconia. Therefore, La is less likely to diffuse from the interconnector molded body into the adhesion layer molded body during firing, whereby the production of lanthanum zirconate between the interconnector and the adhesion layer can be suppressed.

  The fuel cell stack device of the present invention is characterized in that a plurality of the solid oxide fuel cells are electrically connected in series via a current collecting member. The fuel cell module of the present invention is characterized in that the fuel cell stack device is stored in a storage container. The fuel cell device of the present invention is characterized in that the fuel cell module and an auxiliary machine for operating the fuel cell stack device are housed in an outer case.

  In such a fuel cell stack device, a plurality of solid oxide fuel cells having high conductivity between the interconnector and the conductive support are electrically connected in series via a current collecting member. Since it is configured to be connected, high power generation efficiency can be maintained. Furthermore, by storing such a fuel cell stack device, a fuel cell module and a fuel cell device capable of maintaining high power generation efficiency can be obtained.

  In the solid oxide fuel cell of the present invention, the adhesion layer contains zirconia in which a rare earth element of 45 mol% or more is dissolved, so that La, which is a component of the interconnector, diffuses to the adhesion layer side during power generation. Can suppress the reaction between La, which is a component of the interconnector, and Zr, which is a component of the adhesion layer, and suppresses the formation of lanthanum zirconate between the interconnector and the adhesion layer. can do. Thereby, deterioration with time of power generation efficiency can be suppressed, high conductivity between the interconnector and the conductive support can be maintained, and high power generation efficiency can be maintained.

  In the method for producing a solid oxide fuel cell according to the present invention, since zirconia in the adhesion layer molded body is a solid solution of 45 mol% or more of the rare earth element, La is emitted from the interconnector molded body in the adhesion layer molded body during firing. Therefore, the production of lanthanum zirconate between the interconnector and the adhesion layer can be suppressed.

  Furthermore, in the fuel cell stack device of the present invention, a plurality of solid oxide fuel cells having high conductivity between the interconnector and the conductive support are electrically connected in series via the current collecting member. Therefore, high power generation efficiency can be maintained. Moreover, it can be set as the fuel cell module and fuel cell apparatus which can maintain high electric power generation efficiency by accommodating such a fuel cell stack apparatus.

BRIEF DESCRIPTION OF THE DRAWINGS An example of the fuel cell of this invention is shown, (a) is the cross-sectional view, (b) is a perspective view which fractures | ruptures and shows a part. 1 shows an example of a fuel cell stack device of the present invention, (a) is a side view schematically showing the fuel cell stack device, and (b) is a portion surrounded by a dotted frame of the fuel cell stack device of (a). It is the top view to which a part of was expanded. It is an external appearance perspective view which shows an example of the fuel cell module of this invention. It is a disassembled perspective view which shows an example of the fuel cell apparatus of this invention.

  FIG. 1 shows an example of a solid oxide fuel cell (hereinafter abbreviated as a fuel cell) of the present invention, where (a) is a transverse sectional view and (b) is a partially broken perspective view. FIG. In both drawings, each configuration of the fuel cell 10 is partially enlarged.

  This fuel cell 10 is a hollow plate type fuel cell 10 and includes a porous conductive support 1 containing Ni having a flat cross section and an elliptical cylinder shape as a whole. . Inside the conductive support 1, a plurality of fuel gas flow paths 2 are formed in the longitudinal direction at predetermined intervals, and the fuel cell 10 is provided with various members on the conductive support 1. Have a structure.

  As understood from the shape shown in FIG. 1, the conductive support 1 is composed of a pair of flat surfaces n parallel to each other and arcuate surfaces (side surfaces) m connecting the pair of flat surfaces n. Has been. Both surfaces of the flat surface n are formed substantially parallel to each other, and the porous fuel electrode layer 3 is provided so as to cover one surface (lower surface) of the flat surface n and the arcuate surfaces m on both sides, A dense solid electrolyte layer 4 is laminated so as to cover the fuel electrode layer 3. Further, a porous air electrode layer 6 is laminated on the solid electrolyte layer 4 so as to face the fuel electrode layer 3 with the intermediate layer 5 interposed therebetween. An interconnector 8 containing a lanthanum chromite-based perovskite complex oxide is formed on the other flat surface n where the fuel electrode layer 3 and the solid electrolyte layer 4 are not laminated via an adhesion layer 7. .

  As is clear from FIG. 1, the fuel electrode layer 3 and the solid electrolyte layer 4 extend to both sides of the interconnector 8 (adhesion layer 7) via the arcuate surfaces m at both ends, and the conductive support 1 It is comprised so that the surface of may not be exposed outside. 1 shows an example in which the fuel electrode layer 3 overlaps the side surface of the adhesion layer 7 and the solid electrolyte layer 4 overlaps the side surface of the interconnector 8. However, the adhesion layer 7 and the interconnector 8 have appropriate thicknesses. For example, the fuel electrode layer 3 and the solid electrolyte layer 4 can be arranged so as to overlap the side surface of the adhesion layer 7, and a part of the fuel electrode layer 3 overlaps the side surface of the interconnector 8. It can also be arranged. Furthermore, it can also arrange | position so that each edge part of the fuel electrode layer 3, the solid electrolyte layer 4, the contact | adherence layer 7, and the interconnector 8 may overlap in this order.

  Here, in the fuel cell 10, the portion where the fuel electrode layer 3 and the air electrode layer 6 face each other through the solid electrolyte layer 4 functions as an electrode to generate electric power. That is, an oxygen-containing gas such as air is allowed to flow outside the air electrode layer 6, and a fuel gas (hydrogen-containing gas) is allowed to flow through the fuel gas passage 2 in the conductive support 1 to be heated to a predetermined operating temperature. To generate electricity. And the electric current produced | generated by this electric power generation is collected through the interconnector 8 attached to the electroconductive support body 1. FIG.

  Below, each member which comprises the fuel cell 10 of this invention is demonstrated.

  The conductive support 1 is required to be gas permeable in order to allow the fuel gas to permeate to the fuel electrode layer 3 and to be conductive in order to collect current via the interconnector 8. For example, it is preferably formed of Ni and / or NiO and a specific rare earth element oxide.

The specific rare earth element oxide is used to make the thermal expansion coefficient of the conductive support 1 close to the thermal expansion coefficient of the solid electrolyte layer 4, for example, Y, Lu, Yb, Tm, Er, Ho, Oxides of rare earth elements containing at least one selected from Dy, Gd, Sm and Pr can be used in combination with Ni and / or NiO. Specific examples of such rare earth element oxides include Y ₂ O ₃ , Lu ₂ O ₃ , Yb ₂ O ₃ , Tm ₂ O ₃ , Er ₂ O ₃ , Ho ₂ O ₃ , Dy ₂ O ₃ , Gd _2. O ₃ , Sm ₂ O ₃ , Pr ₂ O ₃ can be exemplified, and there is almost no solid solution or reaction with Ni and / or NiO, and the thermal expansion coefficient can be made close to that of the solid electrolyte layer 4. Y ₂ O ₃ and Yb ₂ O ₃ are preferable from the viewpoints of being inexpensive and inexpensive.

  Further, in the present invention, Ni and / or NiO: rare earth element oxide = 35 in that the good conductivity of the conductive support 1 is maintained and the thermal expansion coefficient is approximated to that of the solid electrolyte layer 4. It is preferably present in a volume ratio of 65 to 65:35. The conductive support 1 may contain other metal components and oxide components as long as required characteristics are not impaired.

  Moreover, since the electroconductive support 1 needs to have fuel gas permeability, it is usually preferable that the open porosity is 30% or more, particularly 35 to 50%. The conductivity of the conductive support 1 is preferably 300 S / cm or more, and particularly preferably 440 S / cm or more.

  Note that the length of the flat surface n of the conductive support 1 (length in the width direction of the conductive support 1) is usually 15 to 35 mm, and the length of the arc-shaped surface m (arc length) is 2. The thickness of the conductive support 1 (thickness between the flat surfaces n) is preferably 1.5 to 5 mm.

The fuel electrode layer 3 causes an electrode reaction and is preferably formed of a known porous conductive material. For example, it can be formed of ZrO _{2 in which a} rare earth element is dissolved or CeO _{2 in} which a rare earth element is dissolved, and Ni and / or NiO. As the rare earth element, the rare earth elements exemplified in the conductive support 1 can be used. For example, the rare earth element can be formed from ZrO ₂ (YSZ) in which Y is dissolved, and Ni and / or NiO.

The content of ZrO ₂ in which the rare earth element is dissolved in the fuel electrode layer 3 or CeO ₂ in which the rare earth element is dissolved is preferably in the range of 35 to 65% by volume, and the content of Ni or NiO Is preferably 65 to 35% by volume. Further, the open porosity of the fuel electrode layer 3 is preferably 15% or more, particularly preferably in the range of 20 to 40%, and the thickness thereof is preferably 1 to 30 μm. For example, if the thickness of the fuel electrode layer 3 is too thin, the performance may be deteriorated, and if it is too thick, peeling due to a difference in thermal expansion may occur between the solid electrolyte layer 4 and the fuel electrode layer 3. .

  In the example of FIGS. 1A and 1B, the fuel electrode layer 3 extends to both sides of the adhesion layer 7, but it is sufficient that the fuel electrode layer 3 is formed at a position facing the air electrode layer 6. For example, the fuel electrode layer 3 may be formed only on the flat surface n on the side where the air electrode layer 6 is provided. That is, the fuel electrode layer 3 is provided only on the flat surface n, and the solid electrolyte layer 4 is formed on the fuel electrode layer 3, on both arcuate surfaces m, and on the other flat surface n where the fuel electrode layer 3 is not formed. It may have a different structure.

The solid electrolyte layer 4 uses a dense ceramic made of partially stabilized or stabilized ZrO ₂ containing a rare earth element such as 3 to 15 mol% of Y (yttrium), Sc (scandium), Yb (ytterbium). Is preferred. As the rare earth element, Y is preferable because it is inexpensive. Further, the solid electrolyte layer 4 is desirably a dense material having a relative density (according to Archimedes method) of 93% or more, particularly 95% or more in terms of preventing gas permeation, and a thickness of 5 to 50 μm. Preferably there is.

  The solid electrolyte layer 4 and the air electrode layer 6 are firmly joined between the solid electrolyte layer 4 and the air electrode layer 6 described later, and the components of the solid electrolyte layer 4 and the air electrode layer 6 are The intermediate layer 5 can also be provided for the purpose of suppressing the formation of a reaction layer having a high electric resistance by reacting with the components. In the fuel cell 10 shown in FIG. Show.

Here, the intermediate layer 5 can be formed with a composition containing Ce (cerium) and another rare earth element. For example, the composition formula by molar ratio is (CeO ₂ ) _1-x (REO _{1. 5} ) When expressed as _x , it preferably has a composition satisfying 0 <x ≦ 0.3. Here, RE is preferably at least one of Sm, Y, Yb, and Gd. Furthermore, from the viewpoint of reducing electrical resistance, it is preferable to use Sm or Gd as RE. For example, it is preferably made of CeO ₂ in which 10 to 20 mol% of Sm or Gd is dissolved.

  In addition, the solid electrolyte layer 4 and the air electrode layer 6 are firmly joined, and the components of the solid electrolyte layer 4 and the components of the air electrode layer 6 react to form a reaction layer having high electrical resistance. For the purpose of suppression, the intermediate layer 5 can also be formed of two layers.

The air electrode layer 6 is preferably formed of a conductive ceramic made of a so-called ABO ₃ type perovskite complex oxide. As such a perovskite complex oxide, at least one of LaMnO ₃ complex oxide, LaFeO ₃ complex oxide, and LaCoO ₃ complex oxide in which Sr (strontium) and La (lanthanum) coexist at the A site is used. LaCoO ₃ -based composite oxides are particularly preferable from the viewpoint of high electrical conductivity at an operating temperature of about 600 to 1000 ° C. In the perovskite complex oxide, Fe (iron) and Mn (manganese) may exist at the B site together with Co (cobalt).

  Further, the air electrode layer 6 needs to have gas permeability. Therefore, the conductive ceramic (perovskite complex oxide) forming the air electrode layer 6 has an open porosity of 20% or more, particularly 30 to 50. % Is preferable. Furthermore, the thickness of the air electrode layer 6 is preferably 30 to 100 μm from the viewpoint of current collection.

  An interconnector 8 containing a lanthanum chromite perovskite complex oxide is laminated on the flat surface n opposite to the air electrode layer 6 side of the conductive support 1 with an adhesion layer 7 interposed therebetween. ing.

Although the interconnector 8 is formed of conductive ceramics, it needs to have reduction resistance and oxidation resistance because it is in contact with the fuel gas (hydrogen-containing gas) and the oxygen-containing gas. For this reason, the conductive ceramic having reduction resistance and oxidation resistance generally contains a lanthanum chromite perovskite complex oxide (LaCrO ₃ complex oxide). For the purpose of bringing the coefficient of thermal expansion close to that of the interconnector 8, a LaCrMgO ₃ -based composite oxide in which Mg is present at the B site is used. The molar amount of Mg is specifically 10 to 12 × 10 ⁻⁶ / ° C. so that the thermal expansion coefficient of the interconnector 8 approaches the thermal expansion coefficients of the conductive support 1 and the solid electrolyte layer 4. It can be adjusted as appropriate.

For example, the interconnector 8 containing a lanthanum chromite-based perovskite complex oxide will be described in detail. The interconnector 8 contains a lanthanum chromite-based first complex oxide phase and a second complex oxide phase of Mg and Ni. It is desirable. When the composition formula of the second composite oxide phase is expressed as (Mg _1-x Ni _x ) O, it is desirable that 0.11 ≦ x ≦ 0.66. Within this range, the amount of metallic Ni deposited around the second composite oxide phase becomes an appropriate amount, and the amount of reduction expansion of the lanthanum chromite-based first composite oxide phase and the second composite oxide phase are deposited. Since the amount of reduction shrinkage due to the metal Ni substantially matches, the reduction expansion of the interconnector 8 can be suppressed.

The interconnector 8 can contain an oxide phase as a liquid phase forming component, for example, a Y ₂ O ₃ phase or a Yb ₂ O ₃ phase. Accordingly, the fuel electrode layer 3, the solid electrolyte layer 4 and the like and the interconnector 8 can be simultaneously fired even at a temperature lower than 1500 ° C., for example, 1450 ° C. For this reason, from the conductive support 1 to the interconnector 8 The diffusion of Mg from the Ni and interconnector 8 to the conductive support 1 can be suppressed.

The oxide phase of the liquid phase forming component such as Y ₂ O ₃ is present at the grain boundary between the first composite oxide phase and the second composite oxide phase, and the first composite oxide phase, Mg It is desirable to contain 10 parts by mass or less with respect to 100 parts by mass of the total amount of Ni and the second composite oxide phase containing Ni. In particular, it is desirable to contain 1 to 5 parts by mass from the viewpoint of reducing the open porosity and preventing the aggregation of Y ₂ O _{3 and the} like.

  Further, in order to prevent leakage of the fuel gas passing through the inside of the conductive support 1 and the oxygen-containing gas passing through the outside of the conductive support 1, such conductive ceramics must be dense, for example 93% or more In particular, it is desirable to have a relative density of 95% or more, and considering the electrical resistance, the thickness is desirably 10 to 200 μm. That is, if the thickness is smaller than this range, gas leakage is likely to occur. If the thickness is larger than this range, the electric resistance is large, and the current collecting function may be reduced due to a potential drop.

  Further, an adhesion layer 7 is formed between the conductive support 1 and the interconnector 8 in order to reduce a difference in thermal expansion coefficient between the interconnector 8 and the conductive support 1.

  Such an adhesion layer 7 contains zirconia in which an amount of rare earth elements close to a solid solution limit of 45 mol% or more is dissolved. The reason why zirconia in which 45 mol% or more of the rare earth element is dissolved is used is that when it is less than 45 mol%, the rare earth element is easily dissolved in zirconia and La is easily diffused from the interconnector 8. is there. In particular, it is desirable that the rare earth element is dissolved in zirconia at 50 mol% or more. As the rare earth element, those exemplified in the conductive support 1 can be used. That is, as the rare earth element, for example, at least one selected from Y, Lu, Yb, Tm, Er, Ho, Dy, Gd, Sm, and Pr can be used.

  Furthermore, Ni and / or NiO can be contained in order to improve conductivity. It is preferable that the volume ratio of zirconia in which 45 mol% or more of the rare earth element is dissolved and Ni and / or NiO is 40:60 to 60:40.

  It is desirable that the adhesion layer 7 does not contain La at a site having a depth of 1 μm from the interface with the interconnector 8. The amount of La can be determined by a semi-quantitative analysis method using EPMA (wavelength dispersive X-ray microanalyzer). The fact that La is not contained in the portion of the adhesion layer 7 having a depth of 1 μm from the interface with the interconnector 8 means that the color tone indicating the presence of La is displayed when the La element is shown by a semi-quantitative map using EPMA. A state that cannot be distinguished from the color of the ground.

  Although not shown in FIG. 1, a P-type semiconductor layer 17 (see FIG. 2) is preferably provided on the outer surface (upper surface) of the interconnector 8. By connecting the current collecting member 13 to the interconnector 8 via the P-type semiconductor layer 17, the contact between the two becomes an ohmic contact, the potential drop can be reduced, and a reduction in current collecting performance can be effectively avoided. It becomes.

Examples of such a P-type semiconductor layer 17 include a layer made of a transition metal perovskite complex oxide. Specifically, at least one of those having high electron conductivity, for example, LaMnO ₃ -based composite oxide, LaFeO ₃ -based composite oxide, LaCoO ₃ -based composite oxide in which Mn, Fe, Co, etc. exist at the B site P-type semiconductor ceramics made of can be used. In general, the thickness of the P-type semiconductor layer 17 is preferably in the range of 30 to 100 μm.

  The manufacturing method of the fuel cell 10 of the present invention described above will be described.

First, a clay is prepared by mixing Ni and / or NiO powder, a rare earth element oxide powder such as Y ₂ O ₃ , an organic binder, and a solvent. A conductive support molded body having holes is prepared and dried. As the conductive support molded body, a calcined body obtained by calcining the conductive support molded body at 900 to 1000 ° C. for 2 to 6 hours may be used.

Then, for example, NiO in accordance with a predetermined formulation composition, Y is weighed raw materials of _ZrO 2 (YSZ) was dissolved and mixed. Thereafter, an organic binder and a solvent are mixed with the mixed powder to prepare a fuel electrode layer slurry.

Further, a slurry obtained by adding toluene, a binder, a commercially available dispersant, etc. to a ZrO ₂ powder in which a rare earth element is solid-solubilized is molded to a thickness of 7 to 75 μm by a method such as a doctor blade. A solid electrolyte layer molded body is produced. The fuel electrode layer slurry is applied on the obtained sheet-shaped solid electrolyte layer molded body to form a fuel electrode layer molded body, and the surface on the fuel electrode layer molded body side is laminated on the conductive support molded body. The fuel electrode layer slurry may be formed by coating the slurry for the fuel electrode layer on a predetermined position of the conductive support body and drying it, and then laminating the solid electrolyte layer formed body thereon.

  Subsequently, an intermediate layer 5 disposed between the solid electrolyte layer 4 and the air electrode layer 6 is formed. In the following, an example in which two intermediate layers 5 are formed is shown.

For example, CeO ₂ powder in which Gd is dissolved is heat-treated at 800 to 900 ° C. for 2 to 6 hours, and then wet pulverized to adjust the aggregation degree to 5 to 35, and the raw material for the intermediate layer molded body Adjust the powder. The wet crushing is desirably ball milled for 10 to 20 hours using a solvent. The same applies when the intermediate layer 5 is formed of CeO ₂ powder in which Sm is dissolved.

  Then, toluene is added as a solvent to the raw material powder of the intermediate layer molded body whose cohesion degree has been prepared to prepare a slurry for the intermediate layer, and this slurry is applied onto the solid electrolyte layer molded body to form the first layer A coating film is formed to produce a first layer molded body. In addition, a sheet-like first layer molded body may be produced and laminated on the solid electrolyte layer molded body. Thereafter, a calcination treatment may be performed to produce a calcination body. In the present invention, the calcined body subjected to the calcining process is a concept included in the molded body.

Subsequently, an interconnector material (for example, LaCrMgO ₃ -based composite oxide powder), an organic binder and a solvent are mixed to prepare a slurry, and an interconnector sheet is prepared by a method such as a doctor blade method. A molded product for an interconnector is produced.

Subsequently, an adhesion layer molded body positioned between the conductive support 1 and the interconnector 8 is formed. For example, Yr is mixed so that ZrO ₂ and NiO having a solid solution of 45 mol% or more are in a volume ratio of 40:60 to 60:40, and an organic binder is added to adjust the slurry for the adhesion layer. . The adjusted adhesion layer slurry is applied to a sheet-like interconnector molded body to form an adhesion layer molded body, and the surface on the adhesion layer molded body side is laminated on a conductive support molded body to produce a laminated molded body To do.

  Next, the laminated molded body is subjected to binder removal treatment and co-fired (simultaneous sintering) at 1350 ° C. to 1450 ° C. (more preferably 1400 to 1430 ° C.) for 2 to 6 hours in an oxygen-containing atmosphere. In addition, when the temperature in the simultaneous firing is set to 1500 ° C. or more, the fuel cell 10 may be deformed (for example, when the reduction treatment is performed with the hydrogen-containing gas after the fuel cell 10 is manufactured). Is not preferable).

  In the present invention, since zirconia in the adhesion layer molded body has a rare earth element in a solid solution of 45 mol% or more, there is little room for the rare earth element to further dissolve in the zirconia during firing. Lanthanum hardly diffuses into the adhesion layer molded body, and generation of lanthanum zirconate between the interconnector 8 and the adhesion layer 7 can be suppressed.

  Thereafter, the intermediate layer slurry is formed by applying the slurry for intermediate layer to the surface of the fired first layer sintered body to produce a second layer formed body and sintering it. In sintering the second layer molded body, it is preferably 200 ° C. or more lower than the simultaneous sintering temperature of the solid electrolyte layer 4 and the first layer, for example, preferably 1150 ° C. to 1250 ° C. . In addition, as sintering time for adhering a 2nd layer and a 1st layer, it can be set to 2 to 6 hours.

Further, a slurry containing an air electrode layer material (for example, LaCoO ₃ -based composite oxide powder), a solvent, and a pore increasing agent is applied onto the intermediate layer 5 by dipping or the like. Further, a slurry containing a P-type semiconductor layer material (for example, LaCoO ₃ oxide powder) and a solvent, if necessary, is applied to a predetermined position of the interconnector 8 by dipping or the like. By baking for 6 hours, the fuel cell 10 of the present invention having the structure shown in FIG. 1 (see FIG. 2 for the P-type semiconductor layer 17) can be manufactured. In addition, it is preferable that the fuel cell 10 thereafter causes hydrogen gas to flow through the inside (through hole) to reduce the conductive support 1 and the fuel electrode layer 3. In that case, it is preferable to perform a reduction process at 750-1000 degreeC for 5 to 20 hours, for example.

  FIG. 2 shows an example of a fuel cell stack device configured by electrically connecting a plurality of the above-described fuel cells 10 in series via a current collecting member 13. Is a side view schematically showing the fuel cell stack device 11, (b) is a partially enlarged plan view of the fuel cell stack device 11 of (a), and is a part surrounded by a dotted frame shown in (a) The excerpt is shown. In addition, in (b), the part corresponding to the part surrounded by the dotted line frame shown in (a) is indicated by an arrow, and in the fuel cell 10 shown in (b), the above-described intermediate The layer 5 is omitted, and an example in which a P-type semiconductor layer 17 is provided on the interconnector 8 is shown.

  In the fuel cell stack device 11, the fuel cell stack 12 is configured by arranging the fuel cells 10 via the current collecting member 13, and the lower end of each fuel cell 10 is the fuel cell. It is fixed to the manifold 16 for supplying the fuel gas to the cell 10 with an adhesive such as a glass sealing material. Further, an elastically deformable conductive member 14 having a lower end fixed to the manifold 16 is provided so as to sandwich the fuel cell stack 12 from both ends in the arrangement direction of the fuel cells 10 via the current collecting members 13. .

  Further, in the conductive member 14 shown in FIG. 2, in order to draw out the current generated by the power generation of the fuel cell stack 12 (fuel cell 10) in a shape extending outward along the arrangement direction of the fuel cells 10. Current extraction part 15 is provided.

  Here, in the fuel cell stack apparatus 11 of the present invention, the fuel cell stack 12 is configured by using the fuel cell 10 described above, so that high power generation is achieved by using the fuel cell 10 with little deterioration with time. Efficiency can be maintained and the fuel cell stack apparatus 11 with high reliability can be obtained.

  FIG. 3 is an external perspective view showing an example of a fuel cell module 18 in which the fuel cell stack device 11 of the present invention is accommodated in a storage container 19. FIG. 3 shows an inside of a rectangular parallelepiped storage container 19. The fuel cell stack device 11 shown is accommodated.

  Note that a reformer 20 for reforming raw fuel such as natural gas or kerosene to generate fuel gas is provided above the fuel cell stack 12 in order to obtain fuel gas used in the fuel cell 10. It is arranged. The fuel gas generated by the reformer 20 is supplied to the manifold 16 via the gas flow pipe 21 and supplied to the fuel gas flow path 2 provided inside the fuel cell 10 via the manifold 16. The

  FIG. 3 shows a state in which a part (front and rear walls) of the storage container 19 is removed and the fuel cell stack device 11 and the reformer 20 housed inside are taken out rearward. Here, in the fuel cell module 18 shown in FIG. 3, the fuel cell stack device 11 can be slid and stored in the storage container 19. The fuel cell stack device 11 may include the reformer 20.

  Further, in FIG. 3, the oxygen-containing gas introduction member 22 provided inside the storage container 19 is disposed between the fuel cell stacks 12 juxtaposed to the manifold 16, and the oxygen-containing gas flows into the fuel gas flow. In addition, an oxygen-containing gas is supplied to the lower end of the fuel cell 10 so that the side of the fuel cell 10 flows from the lower end toward the upper end. The temperature of the fuel cell 10 can be increased by burning the fuel gas and the oxygen-containing gas discharged from the fuel gas flow path 2 of the fuel cell 10 on the upper end side of the fuel cell 10. The start-up of the fuel cell stack device 11 can be accelerated. Further, by burning the fuel gas and the oxygen-containing gas discharged from the fuel gas flow path 2 of the fuel cell 10 on the upper end side of the fuel cell 10, the fuel cell 10 (fuel cell stack 12 ) Can be warmed. Thereby, the reforming reaction can be efficiently performed in the reformer 20.

  Furthermore, in the fuel cell module 18 of the present invention, the fuel cell stack device 11 configured using the fuel cells 10 with little deterioration with time is housed in the housing container 19, so that highly reliable fuel The battery module 18 can be obtained.

  FIG. 4 shows an example of the fuel cell device of the present invention in which the fuel cell module 18 shown in FIG. 3 and an auxiliary device (not shown) for operating the fuel cell stack device 11 are housed in an outer case. FIG. In FIG. 4, a part of the configuration is omitted.

  The fuel cell device 23 shown in FIG. 4 divides the inside of an exterior case made up of columns 24 and an exterior plate 25 into upper and lower portions by a partition plate 26, and a module storage chamber 27 for storing the above-described fuel cell module 18 on the upper side thereof. The lower side is configured as an auxiliary equipment storage chamber 28 for storing auxiliary equipment for operating the fuel cell module 18. The auxiliary machines stored in the auxiliary machine storage chamber 28 include a water supply device for supplying water to the fuel cell module 18 and a supply device for supplying fuel gas and air. The equipment is omitted.

  In addition, the partition plate 26 is provided with an air circulation port 29 for flowing the air in the auxiliary machine storage chamber 28 to the module storage chamber 27 side, and a part of the exterior plate 25 constituting the module storage chamber 27 An exhaust port 30 for exhausting the air in the module storage chamber 27 is provided.

  In such a fuel cell device 23, as described above, the highly reliable fuel cell module 18 is housed in the module housing chamber 27, whereby the fuel cell device 23 with improved reliability is obtained. Can do.

  Although the present invention has been described in detail above, the present invention is not limited to the above-described embodiments, and various modifications and improvements can be made without departing from the scope of the present invention.

First, NiO powder having an average particle diameter of 0.5 μm and Y ₂ O ₃ powder having an average particle diameter of 0.9 μm are calcined and reduced, so that the volume ratio is 48% by volume for Ni and 52% by volume for Y ₂ O _3. The kneaded material prepared with an organic binder and a solvent was molded by extrusion molding, dried and degreased to prepare a conductive support molded body. Sample No. In 1, the firing - volume ratio after reduction, Ni _45% by _volume, as Y 2 _{O 3} is 55% by volume, was added and NiO powder and _Y 2 _{O 3} powder.

Next, using a slurry obtained by mixing ZrO ₂ powder (solid electrolyte layer raw material powder) having a particle diameter of 0.8 μm, solid organic electrolyte layer, and a solvent, in which 8 mol% of Y is solid-dissolved by the microtrack method. Then, a solid electrolyte layer sheet having a thickness of 30 μm was prepared by a doctor blade method, and a solid electrolyte layer molded body was produced.

Next, a slurry for the fuel electrode layer is prepared by mixing NiO powder having an average particle size of 0.5 μm, ZrO ₂ powder in which 8 mol% of Y is solid-dissolved, an organic binder, and a solvent, and is applied onto the solid electrolyte layer molded body. Thus, a fuel electrode layer molded body was formed. Then, it laminated | stacked on the predetermined position of the electroconductive support body molded body with the surface at the side of a fuel electrode layer molded body facing down.

  Subsequently, the laminated molded body in which the molded bodies were laminated as described above was calcined at 1000 ° C. for 3 hours.

Next, a composite oxide containing 85 mol% of CeO ₂ and 15 mol% of GdO _1.5 is pulverized by a ball mill using isopropyl alcohol (IPA) as a solvent, and calcined at 900 ° C. for 4 hours. And pulverizing again with a ball mill to adjust the degree of agglomeration of the ceramic particles to obtain an intermediate layer raw material powder. An intermediate layer slurry prepared by adding and mixing an acrylic binder and toluene to this powder is applied on the solid electrolyte layer 4 calcined body of the obtained laminated calcined body by screen printing. A first layer molded body was produced.

Subsequently, La (Cr _0.6 Mg _0.4 ) _0.96 O ₃ powder, which is a lanthanum chromite-based perovskite complex oxide, and 5 parts of MgO powder and 5% of NiO powder with respect to 100 parts by mass of the powder. Part by mass and ₂ parts by mass of Y ₂ O ₃ powder were added and mixed, a slurry in which an organic binder and a solvent were mixed was prepared, an interconnector sheet was prepared, and an interconnector molded body was prepared.

Subsequently, NiO powder having an average particle diameter of 0.5 μm and ZrO ₂ powder having an average particle diameter of 0.5 μm in which rare earth elements of Y, Yb, and Sc are dissolved in the amounts shown in Table 1 (YSZ, YbSZ, ScSZ, respectively) Were added at a volume ratio shown in Table 1, mixed and dried, and an organic binder and a solvent were mixed to prepare an adhesion layer slurry. The adjusted slurry for the adhesion layer is applied to the interconnector molded body to form the adhesion layer molded body, and the surface on the adhesion layer molded body side is formed as a fuel electrode layer molded body (and solid electrolyte layer molding) of the conductive support molded body. The body was laminated on a portion where the body was not formed (a portion where the conductive support molded body was exposed).

  Subsequently, the above-mentioned laminated molded body was subjected to a binder removal treatment, and co-fired for 3 hours in each condition shown in Table 1 in an oxygen-containing atmosphere.

  Next, the intermediate layer slurry is applied to the surface of the fired first layer by a screen printing method to form a second layer molded body, which is 200 ° C. lower than the temperatures shown in Table 1. Sintering was performed for 3 hours.

Next, a mixed liquid composed of La _0.6 Sr _0.4 Co _0.2 Fe _0.8 O ₃ powder having an average particle diameter of 2 μm and isopropyl alcohol was prepared, and the surface of the intermediate layer of the laminated sintered body was formed. Spray coating was performed to form an air electrode layer molded body, which was baked at 1100 ° C. for 4 hours to form an air electrode layer. Thus, the fuel cell shown in FIG. 1 was produced.

  The size of the produced fuel cell is 25 mm × 200 mm, the thickness of the conductive support (thickness between the flat surfaces n) is 2 mm, the open porosity is 35%, the thickness of the fuel electrode layer is 10 μm, and the open porosity. The thickness of the air electrode layer was 24 μm, the open porosity was 40%, and the relative density of the solid electrolyte layer was 97%. The thickness of the adhesion layer was 5 to 10 μm, and the thickness of the interconnector layer was 30 μm.

  Further, when the amount of rare earth element dissolved in zirconia was confirmed for the produced adhesion layer, it was the same as the amount of rare earth element of zirconia used as the raw material powder. The amount of rare earth element dissolved in zirconia can be determined by quantitatively analyzing the amount of rare earth element and Zr by TEM: EDS (energy dispersive spectroscopy) for the zirconia particles in the adhesion layer.

  Next, hydrogen gas was allowed to flow inside the fuel battery cell, and the conductive support and the fuel electrode layer were subjected to reduction treatment at 850 ° C. for 10 hours.

  About the obtained fuel cell, the presence or absence of lanthanum zirconate formation at the interface between the adhesion layer and the interconnector was confirmed by TEM (transmission electron microscope) analysis, and further the potential between the interconnector and the conductive support. The descent was measured.

To measure the potential drop, a Pt current collector is formed on the air electrode layer and the interconnector of the fuel cell, and a voltage wire is attached to the current collector, and at the same time, a Pt wire is inserted into the fuel gas flow path. As an electrode, the fuel cell is heated to 750 ° C., air is supplied to the air electrode layer, fuel gas is supplied to the fuel electrode layer, electric power is generated, current is taken out, and the current density is 0.4 A / cm ² The potential drop between the reference electrode and the interconnector was measured.

  Further, the presence or absence of La at a position of 1 μm from the interface between the adhesion layer and the interconnector was analyzed by a semi-quantitative analysis method using EPMA (wavelength dispersive X-ray microanalyzer) and listed in Table 1.

The fuel cell produced in the present invention was subjected to power generation for 2,000 hours under the conditions of 750 ° C. and 0.6 A / cm ² , and then the interface between the conductive support and the interconnector was observed using EPMA. However, La diffusion did not occur in the sample of the present invention.

  From the results of Table 1, in the adhesion layer (sample Nos. 1 to 5, 8 to 15) in which the solid solution amount of the rare earth element is 45 mol% or more, diffusion of La is suppressed and there is no formation of lanthanum zirconate. It can be seen that a fuel battery cell having a low resistance on the interconnector side (small potential drop) is obtained. Further, in the adhesion layer (sample Nos. 1 to 5) in which the solid solution amount of the rare earth element is 45 mol% or more, the volume ratio of Ni-YSZ is changed from 40:60 to 60:40 (sample No. 1). 1-5), it turns out that the effect is expressed without changing. Furthermore, if the amount of the rare earth element is increased, the formation of lanthanum zirconate is suppressed without being affected by the firing temperature. Furthermore, the sample No. in which the kind of rare earth element was changed was used. 13 and 14 also show that the effect is not changed.

  On the other hand, Sample No. with a rare earth element solid solution amount of less than 45 mol% was used. In 6.7, it can be seen that La diffuses, lanthanum zirconate is formed, and a high resistance layer is formed, so that the potential drop is large.

DESCRIPTION OF SYMBOLS 1 Conductive support body 2 Fuel gas flow path 3 Fuel electrode layer 4 Solid electrolyte layer 5 Intermediate layer 6 Air electrode layer 7 Adhesion layer 8 Interconnector 10 Solid oxide fuel cell 11 Fuel cell stack device 18 Fuel cell module 23 Fuel cell device A: power generation element

Claims (6)

  An electrically conductive support having a fuel gas flow path for allowing fuel gas to flow inside, and an interstitium containing a lanthanum chromite perovskite complex oxide provided on the conductive support via an adhesion layer A solid oxide comprising a connector and a power generation element formed by sequentially laminating a fuel electrode layer, a solid electrolyte layer, and an air electrode layer provided on the conductive support in a portion where the interconnector is not provided A solid oxide fuel cell, wherein the adhesion layer contains zirconia in which 45 mol% or more of a rare earth element is dissolved.   2. The solid oxide fuel cell according to claim 1, wherein the adhesion layer does not contain lanthanum (La) in a portion having a depth of 1 μm from the interface with the interconnector.   An adhesive layer molded body containing zirconia in which a rare earth element is dissolved in an amount of 45 mol% or more is provided on a conductive support molded body having a through hole. Lanthanum (La) and chromium (Cr And an interconnector molded body containing oxide powder containing, and a fuel electrode layer molded body is provided on the conductive support molded body in a portion where the interconnector molded body is not provided, A step of producing a laminated molded body in which a solid electrolyte layer molded body is provided on a fuel electrode layer molded body, a step of firing the laminated molded body, and a solid electrolyte layer formed by sintering the solid electrolyte layer molded body And a step of forming an air electrode layer thereon. A method for producing a solid oxide fuel cell.   3. A fuel cell stack device comprising a plurality of solid oxide fuel cells according to claim 1 or 2 electrically connected in series via a current collecting member.   5. A fuel cell module comprising the fuel cell stack device according to claim 4 housed in a housing container.   6. A fuel cell device, comprising: the fuel cell module according to claim 5; and an auxiliary device for operating the fuel cell stack device in an outer case.

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