JP2011175906A - Cell stack, fuel cell module, and fuel cell device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cell stack, a fuel cell module and a fuel cell device capable of restricting generation of cracks in a conductive connecting material. <P>SOLUTION: In this cell stack 1, the conductive connecting material 14 contains: a perovskite oxide containing Sr; a Si compound; and a reaction product of Sr and Si. Since the density of the reaction product is smaller than that of the perovskite oxide, even if the reaction product is generated, mass of the conductive connecting material 14 does not change, and in comparison with the conductive connecting material 14 before the reaction product is generated, the conductive connecting material 14 is expanded in volume. With this structure, shrinkage of the conductive connecting material 14 can be relaxed and concentration of stress into the conductive connecting material 14 can be restricted to restrict generation of cracks in the conductive connecting material 14. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a cell stack, a fuel cell module, and a fuel cell device.

  In recent years, various fuel cell modules in which a cell stack formed by electrically connecting a plurality of fuel cells is accommodated in a storage container have been proposed as next-generation energy.

  In the cell stack, a current collecting member is disposed between a plurality of fuel cells, and fuel cells adjacent to the current collecting member are joined by a conductive joining material or the like, thereby electrically connecting each fuel cell. It is configured by connecting in series.

  Here, in joining the current collecting member and the fuel battery cell, the conductive joining made of LaSrCoFe-based perovskite type oxide having coarse powder and fine powder having the same composition and different average particle diameters on the surface of the current collecting member. A method of applying a material has been proposed (see, for example, Patent Document 1).

JP 2004-265742 A

  However, when the current collecting member and the fuel cell are joined using a conductive joining material made of LaSrCoFe-based perovskite oxide having the same composition and different coarse particles and fine particles having different average particle sizes, Due to the shrinkage of firing during the production of the stack or the shrinkage of the conductive bonding material during the operation of the fuel cell device, there is a possibility that stress concentrates inside the conductive bonding material and cracks are generated in the conductive bonding material. Furthermore, when a crack occurs in the conductive bonding material, there is a possibility that the conductive bonding material is peeled off from the air electrode layer or the interconnector due to the crack generated in the conductive bonding material.

  Therefore, the object of the present invention is excellent in long-term reliability, which is capable of reducing the shrinkage generated in the conductive bonding material and suppressing the occurrence of cracks even when the cell stack is manufactured or the fuel cell device is operated. The object is to provide a cell stack, a fuel cell module, and a fuel cell device.

In the cell stack of the present invention, a fuel electrode layer and a solid electrolyte layer are laminated in this order on the surface of a conductive support, and an interconnector is provided at a portion where the fuel electrode layer and the solid electrolyte layer are not provided. The surface of the conductive support is covered with the solid electrolyte layer and the interconnector, and an air electrode is disposed on the solid electrolyte layer at a portion facing the interconnector via the conductive support. A plurality of fuel cells stacked in layers are connected to the air electrode layer of one of the adjacent fuel cells and the interconnector of the other adjacent fuel cell via a conductive bonding material, respectively. A cell stack electrically connected in series by a current collecting member,
The conductive bonding material contains a perovskite oxide containing Sr, a Si compound, and a reaction product of Sr and Si, and the density of the reaction product is higher than the density of the perovskite oxide. It is small.

  In such a cell stack, the conductive bonding material contains a perovskite oxide containing Sr, a Si compound, and a reaction product of Sr and Si, and the density of the reaction product is a perovskite oxidation. Since the mass of the conductive bonding material does not change even if a reaction product is generated, the conductive bonding material is smaller than the conductive bonding material before the reaction product is formed. Will expand in volume. As a result, the shrinkage of the conductive bonding material can be alleviated and the stress can be prevented from concentrating inside the conductive bonding material, so that the occurrence of cracks in the conductive bonding material can be suppressed. Therefore, a cell stack with improved long-term reliability can be obtained.

  Furthermore, since it is possible to suppress the occurrence of cracks in the conductive bonding material, the separation between the conductive bonding material and the air electrode layer or the interconnector is suppressed due to the cracks generated in the conductive bonding material. be able to.

In the cell stack of the present invention, the air electrode layer is made of a LaSrCoO ₃ -based perovskite oxide, and the perovskite oxide constituting the conductive bonding material is made of a LaSrCoO ₃ -based perovskite oxide. preferable.

In such a cell stack, the air electrode layer is made of a LaSrCoO ₃ -based perovskite oxide and the perovskite oxide constituting the conductive bonding material is made of a LaSrCoO ₃ -based perovskite oxide. The bonding strength between the conductive bonding material and the conductive bonding material can be improved. Thereby, peeling between the air electrode layer and the conductive bonding material can be further suppressed, and a cell stack with improved long-term reliability can be obtained.

  Since the fuel cell module of the present invention is characterized in that the cell stack is stored in a storage container, the fuel cell module is excellent in long-term reliability.

  The fuel cell device of the present invention is a fuel cell device having excellent long-term reliability since the fuel module and the auxiliary machine for operating the fuel cell module are housed in an outer case. Can do.

  In the cell stack of the present invention, the conductive bonding material contains a perovskite oxide containing Sr, a Si compound, and a reaction product of Sr and Si, and the density of the reaction product is a perovskite oxide. Therefore, the shrinkage of the conductive bonding material can be mitigated, and the stress can be prevented from concentrating inside the conductive bonding material, so that the conductive bonding material can be prevented from cracking. be able to. Therefore, a cell stack with improved long-term reliability can be obtained.

  In addition, the fuel cell module of the present invention can be a fuel cell module having excellent long-term reliability because the cell stack described above is housed in the housing container. The fuel cell device of the present invention is a fuel cell having excellent long-term reliability since the fuel cell module described above and an auxiliary machine for operating the fuel cell module are housed in an outer case. It can be a device.

An example of the cell stack apparatus which comprises the cell stack of this invention is shown, (a) is a side view which shows a cell stack apparatus schematically, (b) is a top view which expands and shows a part of (a) It is. It is sectional drawing which shows roughly joining of the current collection member and fuel cell in the cell stack of this invention. It is an external appearance perspective view which shows an example of the fuel cell module which accommodates the cell stack apparatus which comprises the cell stack of this invention in a storage container. 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 cell stack apparatus comprising the cell stack of the present invention, (a) is a side view schematically showing the cell stack apparatus, and (b) is an enlarged view of part of (a). The figure is an excerpted portion surrounded by a dotted frame shown in FIG. In the following drawings, the same numbers are assigned to the same members.

  Here, the cell stack 2 constituting the cell stack apparatus 1 is an elliptical columnar conductive support body 11 (hereinafter sometimes abbreviated as the support body 11) composed of a pair of opposed flat portions and arc-shaped portions at both ends. A porous fuel electrode layer 8 is provided so as to cover one flat portion and the arc-shaped portion, and a dense solid electrolyte layer 9 is laminated so as to cover the fuel electrode layer 8. Further, a porous air electrode layer 10 is provided on the solid electrolyte layer 9 so as to face the fuel electrode layer 8. That is, the fuel electrode layer 8, the solid electrolyte layer 9, and the air electrode layer 10 are laminated in this order on one flat portion of the support 11. An interconnector 13 is laminated on the other flat portion of the support 11 on which the fuel electrode layer 8 and the solid electrolyte layer 9 are not formed. With such a configuration, the columnar fuel cell 3 is formed. As is apparent from FIG. 1B, the fuel electrode layer 8 and the solid electrolyte layer 9 are extended to both sides of the interconnector 13 via the arc-shaped portions at both ends, and the surface of the support 11 Is configured not to be exposed to the outside.

  The cell stack 2 is configured by electrically connecting a plurality of the fuel cells 3 in series between the adjacent fuel cells 3 via the current collecting member 4. The current collecting member 4 disposed between the adjacent fuel cells 3 is connected to the air electrode layer 10 and the interconnector 13 via the conductive bonding material 14, respectively. They are electrically connected in series.

  And the lower end part of each fuel battery cell 3 which comprises the cell stack 2 mentioned above is fixed to the manifold 7 for supplying fuel gas (hydrogen containing gas) to the fuel battery cell 3, and a lower end part is to the manifold 7. The conductive member 5 is arranged so as to sandwich the cell stack from both ends of the fuel cell 3 in the arrangement direction of the fuel cell 3 via the current collecting member 4, thereby configuring the cell stack device 1.

  Here, in the conductive member 5 shown in FIG. 1, a current extraction portion 6 is provided for extending outward along the arrangement direction of the fuel cells 3 and for extracting a current generated by the power generation of the fuel cells 3. It has been.

  In addition, a plurality of fuel gas passages 12 penetrating in the longitudinal direction are provided in the width direction of the fuel battery cell 3 inside the support body 11 constituting the fuel battery cell 3 and supplied by the manifold 7. The fuel gas is supplied to the fuel electrode layer 8 while flowing upward through the fuel gas flow path 12.

  Further, the support 11 may also serve as the fuel side electrode (fuel electrode layer 8), and the fuel cell 3 can be configured by sequentially laminating the solid electrolyte layer 9 and the air electrode layer 10 on the surface thereof.

Various types of fuel cells are known as the fuel cells 3. However, in order to reduce the size and increase the efficiency of the fuel cell device that houses the fuel cells 3, the solid oxide that operates at high temperatures is used. It can be set as a physical fuel cell. Thereby, the fuel cell device can be reduced in size and increased in efficiency, and a load following operation can be performed to follow a fluctuating load required for a household fuel cell. Furthermore, an efficient solid oxide fuel cell system can be configured by combining heat generated by power generation with a hot water supply system.

  Below, each member which comprises the fuel cell 3 shown in FIG. 1 is demonstrated.

  Since the support 11 is required to be gas permeable in order to permeate the fuel gas to the fuel electrode layer 8 and to be conductive in order to collect current via the interconnector 13, for example, It is preferably formed of an iron group metal component and a specific rare earth oxide.

  Examples of the iron group metal component include an iron group metal element, an iron group metal oxide, an iron group metal alloy or an alloy oxide, and the like. More specifically, for example, iron group metals include Fe, Ni (nickel), and Co. Since they are particularly inexpensive and stable in fuel gas, at least one of Ni and NiO is used as the iron group component. It is preferable to contain.

The specific rare earth oxide is used to bring the thermal expansion coefficient of the support 11 close to the thermal expansion coefficient of the solid electrolyte layer 9 to be described later. Y, Lu (lutetium), Yb, Tm ( A rare earth oxide containing at least one element selected from the group consisting of thulium), Er (erbium), Ho (holmium), Dy (dysprosium), Gd, Sm, Pr (praseodymium), Used in combination. Specific examples of such rare earth 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 the iron group metal oxide, and the thermal expansion coefficient is almost the same as that of the solid electrolyte layer 9. And Y ₂ O ₃ and Yb ₂ O ₃ are preferable because they are inexpensive.

In the present invention, the volume ratio after firing-reduction is Ni: rare earth element oxide in terms of maintaining good conductivity of the support 11 and approximating the thermal expansion coefficient to that of the solid electrolyte layer 9. (For example, Ni: Y ₂ O ₃ ) is preferably in the range of 35:65 to 65:35 (Ni / (Ni + Y) is 65 to 86 mol% in molar ratio). The support 11 may contain other metal components and oxide components as long as required characteristics are not impaired.

  Further, since the support 11 needs to have fuel gas permeability, it is usually preferable that the porosity is 30% or more, particularly 35 to 50%. The conductivity of the support 11 is 50 S / cm or more, preferably 300 S / cm or more, and particularly preferably 440 S / cm or more.

  In addition, the length of the flat part of the support 11 (length in the width direction of the support 11) is usually 15 to 35 mm, and the length of the arc-shaped part (arc length) is 2 to 8 mm. The thickness of the body 11 (thickness between both flat portions) is preferably 1.5 to 5 mm.

The fuel electrode layer 8 causes an electrode reaction, and can be formed from at least one of Ni and NiO, which are iron group metals, and ZrO _{2 in} which a rare earth element is dissolved. In addition, as the rare earth element, the rare earth elements (Y and the like) exemplified in the support 11 can be used.

In the fuel electrode layer 8, and at least one of Ni and NiO, ZrO ₂ content of the rare earth element is solid-solved is fired - volume ratio after reduction, Ni: ZrO ₂ (e.g. a rare earth element in solid solution, NiO: YSZ) is preferably in the range of 35:65 to 65:35. Further, the porosity of the fuel electrode layer 8 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 8 is too thin, the power generation performance may be deteriorated. If the thickness is too thick, peeling due to a difference in thermal expansion coefficient between the solid electrolyte layer 9 and the fuel electrode layer 8 described later is caused. And may cause cracks.

The solid electrolyte layer 9 uses a dense ceramic made of partially stabilized or stabilized ZrO ₂ containing rare earth elements such as 3 to 15 mol% of Y (yttrium), Sc (scandium), Yb (ytterbium), etc. Is preferred. As the rare earth element, Y is preferable because it is inexpensive. Further, the solid electrolyte layer 9 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.

  In addition, the solid electrolyte layer 9 and the air electrode layer 10 are firmly joined between the solid electrolyte layer 9 and the air electrode layer 10 described later, and the components of the solid electrolyte layer 9 and the components of the air electrode layer 10 are An intermediate layer (not shown) can also be provided for the purpose of suppressing the formation of a reaction layer having a high electrical resistance by reaction.

  The air electrode layer 10 needs to have gas permeability. Therefore, the conductive ceramic (perovskite oxide) forming the air electrode layer 10 has a porosity of 20% or more, particularly 30 to 50%. Preferably there is. Furthermore, the thickness of the air electrode layer 10 is preferably 30 to 100 μm from the viewpoint of current collection.

The perovskite oxide that forms the air electrode layer 10 is preferably made of a LaSrCoO ₃ -based perovskite oxide containing Co having high conductivity in the power generation temperature range of the cell stack 2. As the LaSrCoO ₃ -based perovskite oxide, at least one of LaSrCoFeO ₃ -based perovskite oxide (for example, LaSrCoFeO ₃ ) and LaSrCoO ₃ -based perovskite oxide (for example, LaSrCoO ₃ ) is preferable.

The interconnector 13 is preferably formed of conductive ceramics, but is in contact with a fuel gas (hydrogen-containing gas) and an oxygen-containing gas (air), and therefore has interconnected resistance and oxidation resistance. is necessary. For this reason, lanthanum chromite-based perovskite oxides (LaCrO ₃ -based oxides) are generally used as conductive ceramics having reduction resistance and oxidation resistance, and in particular, the support 11 and the solid electrolyte layer 9 For the purpose of bringing the thermal expansion coefficient closer, LaCrO ₃ perovskite oxide is used.

  Further, the thickness of the interconnector 13 is preferably 10 to 50 μm from the viewpoint of preventing gas leakage and electric resistance. If the thickness is smaller than this range, gas leakage is liable to occur. If the thickness is larger than this range, the electric resistance is large, and the current collecting function may be lowered due to a potential drop.

  The current collecting member 4 is preferably configured to have heat resistance and oxidation resistance, and is composed of, for example, a metal containing Cr. As such a current collecting member 4, a pair of plate-like contact portions for making contact with adjacent fuel cells 3 provided at a predetermined interval, and one contact portion of the pair of contact portions. A current collecting member 4 or the like having a configuration in which a plurality of conductive pieces having a connection portion that connects one end of the other contact portion and one end of the other contact portion are continuously formed in the longitudinal direction of the fuel cell 3 can be used. .

  Further, since the interconnector 13 and the current collecting member 4 are electrically connected via the conductive bonding material 14, the contact between the two becomes an ohmic contact, the potential drop can be reduced, and the current collecting performance is reduced. It can be effectively avoided.

  By the way, in the conductive bonding material 14 formed of the perovskite type oxide, stress is generated inside the conductive bonding material 14 due to firing shrinkage at the time of manufacturing the cell stack 2 or shrinkage at the time of operation of the fuel cell device. There is a possibility that cracks are generated inside the conductive bonding material 14 and the long-term reliability of the cell stack 2 is lowered.

  Further, due to a crack generated in the conductive bonding material 14, the conductive bonding material 14 may be separated from the air electrode layer 10 or the interconnector 13. Similarly, the conductive bonding material 14 and the current collecting member 4 may be peeled off due to cracks generated in the conductive bonding material 14.

  FIG. 2 is a cross-sectional view schematically showing the joining of the current collecting member 4 and the fuel cell 3 in the cell stack 2 of the present invention, and the air electrode layer 10 formed on the upper surface of the solid electrolyte layer 9 and the current collector. It shows that the member 4 is connected via the conductive bonding material 14. As shown in FIG. 2, the conductive bonding material 14 is provided on the air electrode layer 10 and the interconnector 13 of the fuel cell 3, and is directly connected to the air electrode layer 10 and the interconnector 13. Not connected. Thereby, the contact area of the current collection member 4 and the fuel cell 3 (the air electrode layer 10 and the interconnector 13) can be increased, and it becomes easy to fix the current collection member 4.

  The conductive bonding material 14 contains a perovskite oxide containing Sr, a Si compound, and a reaction product of Sr and Si.

Examples of the perovskite oxide that constitutes the conductive bonding material 14 include LaSrCoFeO ₃ -based perovskite oxide (eg, La _0.6 Sr _0.4 Co _0.4 Fe _0.6 O ₃ ), LaSrMnO ₃ -based perovskite oxide. (For example, LaSrMnO ₃ ), LaSrFeO ₃ -based perovskite type oxide (for example, LaSrFeO ₃ ), LaSrCoO ₃ -based perovskite type oxide (for example, LaSrCoO ₃ ), LaCoO ₃ -based perovskite type oxide (for example, LaCoFeO ₃ type oxide) Is preferably used.

Further, the same LaSrCoO ₃ perovskite oxide as the air electrode layer 10 described above is preferable, and it is more preferable that it is made of La _0.6 Sr _0.4 Co _0.4 Fe _0.6 O ₃ . Thus, by setting it as the same composition as the air electrode layer 10, the joining strength of the electroconductive bonding material 14 and the air electrode layer 10 can be increased, and peeling between the air electrode layer and the 10 electroconductive bonding material 14 can be performed. Can be suppressed.

Each density of LaSrCoFeO ₃ , LaSrCoO ₃ or LaSrMnO ₃ as the perovskite oxide constituting the air electrode layer 10 or the perovskite oxide constituting the conductive bonding material 14 is 6.3 g / cm3 of LaSrCoFeO _3. ³ , LaSrCoFeO ₃ is 6.3 g / cm ³ , and LaSrCoFeO ₃ is 6.5 g / cm ³ .

  Furthermore, since the conductive bonding material 14 is also bonded to the interconnector 13, the conductive bonding material 14 and the interconnector 13 are connected by bringing the thermal expansion coefficient of the conductive bonding material 14 close to the thermal expansion coefficient of the interconnector 13. It is possible to reduce the thermal stress generated in

The Si compound is required not to shrink (not sinter) in the temperature range (750 to 1000 ° C.) where the cell stack 2 generates power. Therefore, the heat resistant temperature is preferably 1000 ° C. or higher. _Therefore, it is possible to use SiO 2, SiC, mullite compounds. In particular, SiO ₂ and SiC are preferable. Moreover, it is preferable that an average particle diameter is 3-20 micrometers, More preferably, it is 6-10 micrometers. Thereby, shrinkage of the conductive bonding material 14 can be suppressed.

By the way, when the air electrode layer 10 is made of a LaSrCoFeO ₃ perovskite oxide, the thermal expansion coefficient of the air electrode layer 10 is 17.3 × 10 ⁻⁶ / ° C. Also, if the interconnector 13 is made of LaCrO ₃ perovskite oxide, the thermal expansion coefficient of the interconnector 13 is 9.5 × ^{10 -6} / ℃. The coefficient of thermal expansion of the alloy containing Cr constituting the current collecting member 4 is 12.8 × 10 ⁻⁶ / ° C. Therefore, the thermal expansion coefficient of the conductive bonding material 14 bonded to the air electrode layer 10 and the interconnector 13 is set to be larger than the thermal expansion coefficient of the interconnector 13 and smaller than the thermal expansion coefficient of the air electrode layer 10. Is preferred.

The thermal expansion coefficient of the Si compound constituting the conductive bonding material 14 is, for example, 7.2 × 10 ⁻⁶ / ° C. for SiO ₂ , 4 × 10 ⁻⁶ / ° C. for SiC, and 5.3 × 10 ^{−6 for} mullite compound. Since it is / ° C., the thermal expansion coefficient of the conductive bonding material 14 can be reduced by containing the Si compound in the conductive bonding material 14, and peeling from the interconnector 13 can be suppressed.

  Moreover, it is preferable that Si compound is contained 10 to 35 mass%. From the viewpoint of the electrical conductivity and thermal expansion coefficient of the conductive bonding material 14, it is more preferable that the content is 10 to 25% by mass.

  The Si compound reacts with the perovskite oxide containing Sr constituting the conductive bonding material 14 to form a reaction product. More specifically, Sr in the perovskite oxide containing Sr reacts with Si in the Si compound to form a reaction product having a density smaller than that of the perovskite oxide. Since the mass of the conductive bonding material 14 does not change and a reaction product having a low density is formed, the conductive bonding material 14 undergoes volume expansion. Thereby, shrinkage of the conductive bonding material 14 can be suppressed, and generation of cracks in the conductive bonding material 14 can be suppressed. Furthermore, since generation | occurrence | production of a crack is suppressed, peeling from the fuel cell 3 (the air electrode layer 10 and the interconnector 13) and the current collection member 4 can be suppressed resulting from a crack.

  Here, each reaction product will be described.

A compound containing Si element such as SiO ₂ or SiC reacts with Sr in the perovskite oxide constituting the conductive bonding material 14 to generate SrSiO ₃ . SrSiO ₃ has a density of 3.7 g / cm ³ , a thermal expansion coefficient of 7.2 × 10 ⁻⁶ / ° C., and does not sinter at 750 to 1000 ° C. Therefore, SrSiO ₃ itself does not shrink and the density is Since it is smaller than the perovskite type oxide containing Sr, when the reaction product is formed, the volume of the conductive bonding material 14 expands, and the shrinkage of the conductive bonding material 14 can be effectively suppressed. it can.

The mullite compound containing Sr ₂ Al ₂ O ₇ reacts with Sr and Co of the perovskite oxide constituting the conductive bonding material 14. Sr ₂ Al ₂ O ₇ has a density of 3.8 g / cm ³ , a thermal expansion coefficient of 5.3 × 10 ⁻⁶ / ° C., and does not sinter at 750 to 1000 ° C. Therefore, Sr ₂ Al ₂ O ₇ Since it does not shrink itself and the density is smaller than that of the perovskite oxide containing Sr, the shrinkage of the conductive bonding material 14 can be suppressed.

Further, detection of cracks in the conductive bonding material 14 and separation of the conductive bonding material 14 from the current collecting member 4 and the fuel cell 3 will be described. Cracks generated on the surface of the conductive bonding material 14 and peeling of the conductive bonding material 14 from the current collecting member 4 and the fuel cell 3 can be detected by observation using a loupe or the like. Further, the fuel cell 3 is cut so that the interface between the fuel cell 3 and the conductive bonding material 14 or the interface between the current collecting member 4 and the conductive bonding material 14 can be confirmed, and the cut section is photographed with a scanning line electron microscope (SEM). By doing so, it is possible to detect cracks and peeling occurring inside the conductive bonding material 14.

  The members constituting the fuel cell 3 according to the present invention have been described above. Next, a method for producing the fuel cell 3 (cell stack 2) according to the present invention will be described.

First, a clay is prepared by mixing an iron group metal such as Ni or its oxide powder, a rare earth oxide powder such as Y ₂ O ₃ , an organic binder, and a solvent, and using this clay A support molded body is prepared by extrusion molding and dried. In addition, you may use the calcined body which calcined the support body molded object at 900-1000 degreeC for 2 to 6 hours as a support body molded object.

Next, for example, ZrO ₂ (YSZ) raw material in which NiO and Y ₂ O ₃ are dissolved is weighed and mixed according to a predetermined composition. Then, 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 support molded body. Alternatively, the fuel electrode layer slurry may be applied to a predetermined position of the support body molded body and dried, and the solid electrolyte layer molded body coated with the fuel electrode layer slurry may be laminated on the conductive support body molded body.

Subsequently, an interconnector material (for example, LaCrO ₃ oxide powder), an organic binder, and a solvent are mixed to prepare a slurry, an interconnector sheet is prepared, and a solid electrolyte layer molded body is not formed. Laminate on the exposed surface of the body compact.

  Next, the above-mentioned laminated molded body is subjected to binder removal treatment and co-fired in an oxygen-containing atmosphere at 1400-1600 ° C. for 2-6 hours.

Subsequently, a slurry for an air electrode layer containing LaSrCoFeO ₃ oxide powder and a solvent was applied onto the solid electrolyte layer 9 by screen printing, dried, and then fired at 1100 to 1200 ° C. for 1 to 3 hours. To do. The fuel cell 3 can be manufactured through the above steps.

Subsequently, a LaSrCoFeO ₃ powder having an average particle diameter of 1 μm, SiO ₂ having an average particle diameter of 10 μm as an Si compound, an organic binder, and a solvent are mixed to produce a slurry for conductive bonding material, and air is printed by screen printing. It is applied on the polar layer 10 and the interconnector 13.

  Immediately after coating by the screen printing method, the current collecting member 4 is bonded, dried, and baked. Thereby, the cell stack formed by interposing the current collecting member 4 between the fuel battery cells 3 can be formed.

  In addition, it is preferable that the fuel cell 3 thereafter circulates a hydrogen-containing gas (fuel gas) therein to perform the reduction treatment of the support 11 and the fuel electrode layer 8. In that case, it is preferable to perform a reduction process at 750-1000 degreeC for 5 to 20 hours, for example.

Moreover, although the example in which the conductive bonding material 14 is formed on the air electrode 10 and the interconnector 13 by screen printing has been described, the conductive bonding material 14 may be formed using other methods. For example, the current collecting member 4 is dipped in the above-described slurry for conductive bonding material, and the air electrode 10 of one fuel cell 3 and the interconnector 13 of the other fuel cell 3 are electrically connected between the fuel cells 3. The cell stacks can be easily manufactured by arranging them so as to be connected, bonding, drying, and firing.

  FIG. 3 is an external perspective view showing an example of a fuel cell module 17 in which the cell stack device 1 of the present invention is housed in a housing container. The cell shown in FIG. The stack apparatus 1 is accommodated.

  A reformer 19 for reforming raw fuel such as natural gas or kerosene to generate fuel gas is disposed above the cell stack 2 in order to obtain fuel gas used in the fuel cell 3. ing. The fuel gas generated by the reformer 19 is supplied to the manifold 7 via the gas flow pipe 20 and is supplied to the fuel gas flow path provided inside the fuel battery cell 3 via the manifold 7. .

  FIG. 3 shows a state in which a part (front and rear surfaces) of the storage container 18 is removed, and the cell stack device 1 and the reformer 19 housed inside are taken out rearward. Here, in the fuel cell module 17 shown in FIG. 3, the cell stack device 1 can be slid and stored in the storage container 18. The cell stack device 1 may include a reformer 19.

  Further, in FIG. 3, the oxygen-containing gas introduction member 21 provided in the storage container 18 is disposed between the cell stacks 2 juxtaposed on the manifold 7 and the oxygen-containing gas is matched to the flow of the fuel gas. The oxygen-containing gas is supplied to the lower end of the fuel cell 3 so that the fuel cell 3 flows laterally from the lower end toward the upper end. Then, the fuel gas discharged from the fuel gas flow path of the fuel battery cell 3 and the oxygen-containing gas are combusted on the upper end side of the fuel battery cell 3 to increase or maintain the temperature of the fuel battery cell 3 at a high temperature. In addition to speeding up the activation of the cell stack device 1, the power generation efficiency can be improved. Further, the fuel gas discharged from the fuel gas flow path of the fuel battery cell 3 and the oxygen-containing gas are combusted on the upper end side of the fuel battery cell 3 so that the upper side of the fuel battery cell 3 (cell stack 1). It is possible to efficiently warm the reformer 19 disposed in the. Thereby, the reforming reaction can be efficiently performed in the reformer 19.

  Furthermore, in the fuel cell module 17 of the present invention, since the cell stack device 1 configured using the cell stack 2 with improved long-term reliability is stored in the storage container 18, the long-term reliability is improved. The fuel cell module 17 can be obtained.

  4 is an exploded perspective view showing an example of the fuel cell device of the present invention in which the fuel cell module 17 shown in FIG. 3 and an auxiliary machine for operating the fuel cell stack device 1 are housed in an outer case. FIG. In FIG. 4, a part of the configuration is omitted.

  The fuel cell device 22 shown in FIG. 4 divides the inside of an exterior case composed of a support column 23 and an exterior plate 24 into upper and lower portions by a partition plate 25, and a module storage chamber 26 for storing the above-described fuel cell module 17 on the upper side. The lower side is configured as an auxiliary equipment storage chamber 27 for storing auxiliary equipment for operating the fuel cell module 17. It should be noted that auxiliary equipment stored in the auxiliary equipment storage chamber 27 is omitted.

  Further, the partition plate 25 is provided with an air circulation port 28 for flowing the air in the auxiliary machine storage chamber 27 to the module storage chamber 26 side, and a part of the exterior plate 24 constituting the module storage chamber 26 An exhaust port 29 for exhausting the air in the module storage chamber 26 is provided.

  In such a fuel cell device 22, as described above, the fuel cell module 17 that can improve long-term reliability is housed in the module housing chamber 26, so that the fuel with improved long-term reliability can be obtained. The battery device 22 can be obtained.

  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 paper of the present invention.

  For example, in the fuel battery cell 3 of the present invention, a hollow flat plate is shown, but the present invention can also be used in a cylindrical fuel battery cell.

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.

Next, a slurry for a fuel electrode layer in which a NiO powder having an average particle size of 0.5 μm, a ZrO ₂ powder in which Y ₂ O ₃ is solid-solved, an organic binder, and a solvent are mixed is prepared, and a screen printing method is performed on the support body. Was applied and dried to form a coating layer for the fuel electrode layer. Next, using a slurry obtained by mixing a ZrO ₂ powder (raw material powder for a solid electrolyte layer) having a particle diameter of 0.8 μm by a microtrack method in which 8 mol% of yttrium was dissolved, an organic binder, and a solvent, A sheet for a solid electrolyte layer having a thickness of 30 μm was prepared by a doctor blade method. The sheet for the solid electrolyte layer was attached on the coating layer for the fuel electrode layer and dried.

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

Subsequently, a slurry for an interconnector in which a LaCrO ₃ oxide, an organic binder, and a solvent are mixed is prepared, and this is laminated on the exposed support calcined body where the solid electrolyte layer calcined body is not formed. And co-firing at 1510 ° C. in the atmosphere for 3 hours.

Next, a mixed liquid composed of LaSrCoFeO ₃ powder having an average particle diameter of 1 μm and isopropyl alcohol was prepared, and spray-coated on the surface of the intermediate layer of the laminated sintered body to form an air electrode layer molded body. Was baked in 4 hours to form an air electrode layer, and a fuel cell was produced.

  Next, a raw material powder of a perovskite oxide having an average particle diameter of 1 μm of each composition described in Table 1, a Si compound having an average particle diameter of 10 μm of each composition described in Table 1, isopropyl alcohol, and a pore former, The mixed liquid consisting of was applied onto the air electrode layer and the interconnector by screen printing.

  Next, a pair of plate-shaped contact portions for contacting adjacent fuel cells provided at a predetermined interval, one end of one contact portion and one end of the other contact portion of the pair of contact portions A current collecting member formed by continuously forming a plurality of conductive pieces in the longitudinal direction of the fuel cell (for example, a pair of connection portions along the longitudinal direction of the fuel cell, and The current collecting member comprising a contact portion provided so as to bridge the connecting portion of the battery was disposed between the fuel cells, dried after bonding, and then fired at 1150 ° C. for 2 hours. In addition, the fuel gas was distribute | circulated to the fuel cell after baking at 850 degreeC for 10 hours, and the reduction process was performed.

  A current stacking member was connected between the five fuel cells thus formed via a conductive bonding material to prepare a cell stack.

  Next, the presence or absence of crack generation in the fabricated cell stack was observed using a loupe. The subsequent test was also performed on the cell stack in which cracks had occurred.

Subsequently, the fuel gas is circulated through the fuel gas flow path of the obtained fuel battery cell, the oxygen-containing gas is circulated outside the fuel battery cell, and the fuel battery cell is heated to 750 ° C. using an electric furnace, A power generation test was conducted for 1000 hours under a current density of 0.3 A / cm ² .

  After the power generation test, the presence or absence of cracks in the cell stack was confirmed by the same method as described above.

  Moreover, the composition of the reaction product contained in the conductive bonding material was confirmed by XRD (X-ray diffraction) after completion of the power generation test, and listed in Table 1.

  As shown in Table 1, Sample No. which does not contain Si compound in the conductive bonding material. In No. 1, a crack was generated in the conductive bonding material both during the production of the cell stack and after the completion of the power generation test.

  On the other hand, Sample No. containing Si compound in the conductive bonding material. In Nos. 2 to 10, no crack was generated during the production of the cell stack.

  Thus, it was found that the inclusion of the Si compound in the conductive bonding material suppresses the shrinkage of the conductive bonding material and effectively suppresses the generation of cracks in the conductive bonding material.

  Sample No. containing 10 to 25% by mass of the Si compound was used. In 2-5 and 10, no crack was generated in the conductive bonding material even after the power generation test was completed.

1: Cell stack device 2: Cell stack 3: Fuel cell 4: Current collecting member 8: Fuel electrode layer 9: Solid electrolyte layer 10: Air electrode layer 11: Conductive support 13: Interconnector 14: Conductive bonding material 17: Fuel cell module 22: Fuel cell device

Claims (4)

A fuel electrode layer and a solid electrolyte layer are laminated in this order on the surface of the conductive support, and an interconnector is disposed at a portion where the fuel electrode layer and the solid electrolyte layer are not provided. The solid electrolyte layer And a fuel in which an air electrode layer is laminated on the solid electrolyte layer at a portion facing the interconnector through the conductive support, and the surface of the conductive support is covered by the interconnector. A plurality of battery cells are electrically connected to the air electrode layer of one of the adjacent fuel battery cells and the interconnector of the other adjacent fuel battery cell by a current collecting member through a conductive bonding material, respectively. A cell stack connected in series,
The conductive bonding material contains a perovskite oxide containing Sr, a Si compound, and a reaction product of Sr and Si, and the density of the reaction product is higher than the density of the perovskite oxide. Cell stack characterized by being small. Wherein with the air electrode layer is made of LaSrCoO ₃ type perovskite oxide, according to claim 1, wherein the perovskite oxide constituting the conductive bonding material is characterized by comprising the LaSrCoO ₃ type perovskite oxide Cell stack.   A fuel cell module comprising the cell stack according to claim 1 stored in a storage container.   4. A fuel cell device comprising: the fuel cell module according to claim 3; and an auxiliary device that controls the operation of the fuel cell module.

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