JP6110524B2 - Solid oxide fuel cell, cell stack device, and fuel cell module - Google Patents

Description

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

  In recent years, various fuel cell modules in which solid oxide fuel cells are accommodated in a storage container have been proposed as next-generation energy.

  As such a solid oxide fuel cell, a conductive support having a pair of flat surfaces parallel to each other, a fuel gas passage for allowing fuel gas to circulate therein, and containing Ni A solid oxide fuel cell (hereinafter, simply referred to as a stack of fuel electrode layers, a solid electrolyte layer, and an oxygen electrode layer in this order on a flat surface on one side of the substrate, and an interconnector on the flat surface on the other side. It is sometimes called a fuel cell).

  A fuel cell in which an intermediate layer is formed between the solid electrolyte layer and the oxygen electrode layer so as not to react between the solid electrolyte layer and the oxygen electrode layer is known (for example, Patent Document 1, 2).

  In such a fuel cell, the intermediate layer is composed of a dense first intermediate layer formed on the solid electrolyte layer side and a porous second intermediate layer formed on the oxygen electrode layer side. .

The oxygen electrode layer is made of LaSrCoFeO ₃ , the first intermediate layer, and the second intermediate layer are made of (CeO ₂ ) _1-x (REO _1.5 ) _x (wherein RE is Sm, etc.) By forming a layered electrically insulating Sr zirconate between the intermediate layer and the solid electrolyte layer, the bonding strength between the intermediate layer and the solid electrolyte layer can be improved.

JP 2008-78126 A JP 2010-3478 A

  However, in the fuel cell described in Patent Documents 1 and 2, the electrically insulating Sr zirconate is formed in a layer between the dense first intermediate layer and the solid electrolyte layer, and this layered Sr When the thickness of the zirconate is thick, there is a problem that the electric resistance between the solid electrolyte layer and the oxygen electrode layer becomes high and the power generation performance is lowered.

  An object of the present invention is to provide a solid oxide fuel cell, a cell stack device, and a fuel cell module having low electrical resistance between a solid electrolyte layer and an oxygen electrode layer.

A solid oxide fuel cell according to the present invention includes a solid electrolyte layer made of zirconia, a fuel electrode layer provided on one side of the solid electrolyte layer, and a perovskite type containing La and Sr provided on the other side. An oxygen electrode layer made of a complex oxide, a dense first intermediate layer between the solid electrolyte layer and the oxygen electrode layer , made of ceria and provided on the solid electrolyte layer side; and the oxygen A porous second intermediate layer provided on the extreme layer side, and at the crystal grain boundary of the first intermediate layer that is smaller than the crystal grain boundary of the second intermediate layer, the solid electrolyte A plurality of columnar Sr zirconates extending from the layer side to the oxygen electrode layer side are provided .

  The cell stack device of the present invention comprises a plurality of the above solid oxide fuel cells and is electrically connected to the plurality of solid oxide fuel cells.

  The fuel cell module according to the present invention is characterized in that a plurality of the above solid oxide fuel cells are accommodated in a storage container.

  In the solid oxide fuel cell of the present invention, a columnar Sr zirconate extending from the solid electrolyte layer side to the oxygen electrode layer side is formed in the intermediate layer, and an electric insulation resistance is provided between the intermediate layer and the solid electrolyte layer. The layered Sr zirconate is not formed or is very thin even if it is formed. This can reduce the electrical resistance between the solid electrolyte layer and the oxygen electrode layer, and improve the power generation performance. As a fuel cell module, power generation performance can be improved.

1 shows a solid oxide fuel cell, where (a) is a cross-sectional view and (b) a schematic view of an intermediate layer and its vicinity. It is a scanning electron microscope (SEM) photograph of the intermediate | middle layer of a solid oxide fuel cell, and its vicinity. An example of a fuel cell stack device is shown, (a) is a side view schematically showing the fuel cell stack device, (b) is a part of a portion surrounded by a broken line of the fuel cell stack device of (a). It is sectional drawing expanded and shown. It is an external appearance perspective view which shows an example of a fuel cell module. It is a perspective view which abbreviate | omits and shows a part of fuel cell apparatus.

  1A and 1B show an example of a solid oxide fuel cell according to the present embodiment, in which FIG. 1A is a transverse cross-sectional view thereof, and FIG. 1B is a schematic cross-sectional view of an intermediate layer and the vicinity thereof. Is the SEM photograph. In FIG. 1, each configuration of the fuel battery 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. . A plurality of fuel gas flow paths 2 are formed in the longitudinal direction (perpendicular to the paper surface) at appropriate intervals inside the conductive support 1, and the fuel cell 10 is connected to the conductive support 1. It has a structure in which various members are provided.

  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 a porous fuel electrode layer 3 is provided so as to cover one flat surface n (lower surface) and the arcuate surfaces m on both sides. A dense solid electrolyte layer 4 is laminated so as to cover the electrode layer 3. A porous oxygen 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 is formed on the other flat surface n (upper surface) on which the fuel electrode layer 3 and the solid electrolyte layer 4 are not stacked, with an adhesion layer 7 interposed therebetween.

That is, the fuel electrode layer 3 and the solid electrolyte layer 4 are formed to the other flat surface n (upper surface) via the arcuate surfaces m at both ends, and both end portions of the solid electrolyte layer 4 made of a zirconia-based sintered body. In addition, both ends of the interconnector 8 made of a LaCrO ₃ based sintered body are joined, and the conductive support 1 is surrounded by the solid electrolyte layer 4 and the interconnector 8 so that the fuel gas flowing inside does not leak to the outside. It is configured.

  In the fuel cell 10, the portion where the fuel electrode layer 3 and the oxygen 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 oxygen electrode layer 6 and a fuel gas (hydrogen-containing gas) is allowed to flow through the fuel gas flow path 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 form 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 formed of Ni and / or NiO and a metal oxide, and a specific rare earth oxide is particularly preferable as the metal oxide.

The specific rare earth oxide is used to bring the thermal expansion coefficient of the conductive support 1 close to the thermal expansion coefficient of the solid electrolyte layer 4, and is Y, Lu, Yb, Tm, Er, Ho, Dy. Rare earth oxides containing at least one element selected from the group consisting of, Gd, Sm and Pr can be used in combination with Ni and / or NiO. 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, there is almost no solid solution and reaction with Ni and / or NiO, the thermal expansion coefficient is the same as that of the solid electrolyte layer 4, and From the point of being cheap, Y ₂ O ₃ and Yb ₂ O ₃ are preferable.

  In the present embodiment, Ni and / or NiO: rare earth oxide = 35: 65 in terms of maintaining good conductivity of the conductive support 1 and approximating the thermal expansion coefficient to that of the solid electrolyte layer 4. It is preferably present in a volume ratio of ~ 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 length of the conductive support 1 is 100 to 150 mm.

The fuel electrode layer 3 causes an electrode reaction, and is preferably formed of a known porous conductive ceramic. 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 65 to 35% by volume is preferable. 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.

  In the example of FIG. 1A, 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 oxygen electrode layer 6; The fuel electrode layer 3 may be formed only on the flat surface n on the side where the layer 6 is provided. That is, the fuel electrode layer 3 is provided only on the flat surface n, the solid electrolyte layer 4 is on the fuel electrode layer 3, the arcuate surfaces m of the conductive support 1, and the other flat surface on which the fuel electrode layer 3 is not formed. It may have a structure formed on the surface n.

The solid electrolyte layer 4 is preferably made of a dense ceramic made of partially stabilized or stabilized ZrO ₂ containing 3 to 15 mol% of a rare earth element such as Y, Sc or Yb. 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.

  It should be noted that the solid electrolyte layer 4 and the oxygen electrode layer 6 are firmly joined between the solid electrolyte layer 4 and the oxygen electrode layer 6 described later, and the components of the solid electrolyte layer 4 and the oxygen electrode layer 6 are The intermediate layer 5 is provided for the purpose of suppressing the formation of a reaction layer having a high electrical resistance due to the reaction.

Here, the intermediate layer 5 can be formed with a composition containing Ce and another rare earth element other than Ce. For example, (CeO ₂ ) _1-x (REO _1.5 ) _x (wherein , RE is at least one of Sm, Y, Yb, and Gd, and x preferably has a composition represented by 0 <x ≦ 0.3. Furthermore, from the viewpoint of reducing electric resistance, it is preferable to use Sm or Gd as RE, and for example, it is preferable to consist of CeO ₂ in which 15 to 25 mol% of SmO _1.5 or GdO _1.5 is dissolved. .

The oxygen electrode layer 6 is preferably formed of a conductive ceramic made of a so-called ABO ₃ type perovskite oxide containing La and Sr. As such a perovskite complex oxide, at least one of transition metal perovskite oxides, particularly LaMnO ₃ oxides, LaFeO ₃ oxides, and LaCoO ₃ oxides in which Sr and La coexist at the A site is preferable. LaCoO ₃ -based oxides are particularly preferred because of their high electrical conductivity at an operating temperature of about 600 to 1000 ° C. In the perovskite oxide, Fe and Mn may exist together with Co at the B site.

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

  An interconnector 8 is stacked on the flat surface n on the opposite side of the conductive support 1 from the oxygen electrode layer 6 via an adhesion layer 7.

The interconnector 8 is made of conductive ceramics. In order to come into contact with fuel gas (hydrogen-containing gas) and oxygen-containing gas, it is necessary to have reduction resistance and oxidation resistance. 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 particularly the conductive support 1 and the solid electrolyte layer 4. For the purpose of bringing the coefficient of thermal expansion close to that of LaCrMgO ₃ oxide in which Mg is present at the B site.

  The thickness of the interconnector 8 is preferably 10 to 50 μm from the viewpoint of preventing gas leakage and electrical resistance. Within this range, gas leakage can be prevented and electrical resistance can be reduced.

  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 can have a composition similar to that of the fuel electrode layer 3. For example, it can be formed from at least one of rare earth oxide, ZrO _{2 in which} a rare earth element is dissolved, and CeO ₂ in which a rare earth element is dissolved, and Ni and / or NiO. More specifically, for example, a composition composed of Y ₂ O ₃ and Ni and / or NiO, a composition composed of ZrO ₂ (YSZ) in which Y is solid-solved and Ni and / or NiO, Y, Sm, Gd and the like are solid. It can be formed from a composition comprising dissolved CeO ₂ and Ni and / or NiO. The volume ratio of ZrO ₂ (CeO ₂ ) in which rare earth oxide or rare earth element is dissolved and Ni and / or NiO is preferably in the range of 40:60 to 60:40.

In the intermediate layer 5 of this embodiment, a plurality of columnar Sr zirconates (columnar SrZrO ₃ ) 9 extending from the solid electrolyte layer 4 side to the oxygen electrode layer 6 side are formed. The columnar Sr zirconate 9 is formed at the grain boundaries of the crystal grains constituting the intermediate layer 5. Whether or not the columnar Sr zirconate 9 is formed at the grain boundaries of the crystal grains of the intermediate layer 5 can be confirmed from a scanning electron microscope (SEM) photograph of an arbitrary cross section of the intermediate layer 5.

  In this embodiment, the intermediate layer 5 has a first intermediate layer 5a formed on the solid electrolyte layer 4 side and a second intermediate layer 5b formed on the oxygen electrode layer 6 side, and the first intermediate layer 5a Columnar Sr zirconate 9a is formed on the surface. The second intermediate layer 5 b is porous, and Sr zirconate 9 b is also formed on the inner surfaces of the pores of the second intermediate layer 5.

  The average width of the columnar Sr zirconate 9a in the first intermediate layer 5a is 0.1 to 0.6 μm. The average width of the columnar Sr zirconate 9a can be obtained based on an SEM photograph in an arbitrary cross section of the intermediate layer 5. The first intermediate layer 5a is formed by firing at a temperature higher than that of the second intermediate layer 5b.

  As described above, the intermediate layer 5 can be formed with a composition containing Ce and another rare earth element other than Ce, and the first intermediate layer 5a and the second intermediate layer 5b are made of the same material. Yes.

The first intermediate layer 5a and the second intermediate layer 5b can also be formed from different materials, for example, (CeO ₂ ) _1-x (REO _1.5 ) _x (wherein RE is Sm, Y, Yb and Gd, where x is a number satisfying 0 <x ≦ 0.3), materials having different values of x can be used, and materials having different REs can be used. it can.

  The thickness of the first intermediate layer 5a is 0.2 to 2.0 μm, and the thickness of the second intermediate layer 5b is 3 to 15 μm.

  The first intermediate layer 5a is dense with a porosity of 1 to 5%, and the second intermediate layer 5b is porous with a porosity of 10 to 40%.

  An example of a method for producing the fuel battery cell 10 described above will be described.

First, for example, Ni and / or NiO powder, a rare earth oxide powder such as Y ₂ O ₃ , an organic binder, and a solvent are mixed to prepare a clay, and this clay is used for extrusion molding. A conductive support molded body is prepared and dried. In addition, 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.

Next, the raw material of ZrO ₂ (YSZ) in which NiO and Y ₂ O ₃ are dissolved, for example, is weighed and mixed according to a predetermined composition. Thereafter, an organic binder and a solvent are mixed with the mixed powder to prepare a slurry for the fuel electrode layer.

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 slurry for the fuel electrode layer may be applied to a predetermined position of the conductive support molded body and dried, and the solid electrolyte layer molded body may be laminated on the conductive support molded body (fuel electrode layer molded body).

  Subsequently, the intermediate layer 5 is formed.

For example, CeO ₂ powder in which GdO _1.5 is dissolved is heat-treated at 800 to 900 ° C. for 2 to 6 hours to prepare raw material powders for the first and second intermediate layer molded bodies.

  Then, a solvent is added to the raw material powder of the first intermediate layer molded body to produce a first intermediate layer slurry, and this slurry is applied onto the solid electrolyte layer molded body to form a coating film of the first intermediate layer. And a molded object is produced. In addition, a sheet-like molded body may be produced and laminated on the solid electrolyte layer molded body.

Subsequently, a material for an interconnector (for example, LaCrMgO ₃ oxide powder), an organic binder, and a solvent are mixed to prepare a slurry, and an interconnector sheet is prepared.

Subsequently, an adhesion layer molded body positioned between the conductive support 1 and the interconnector 8 is formed. For example, ZrO ₂ in which Y is dissolved and NiO are mixed and dried so that the volume ratio is in the range of 40:60 to 60:40, an organic binder or the like is added to adjust the slurry for the adhesion layer, and the conductivity An adhesive layer molded body is formed by coating on a support molded body, and an interconnector sheet is laminated on the adhesive layer molded body.

  Subsequently, the above-mentioned laminated molded body is subjected to binder removal treatment and simultaneously sintered (simultaneously fired) in an oxygen-containing atmosphere at 1400 to 1485 ° C. for 1 to 2 hours. Thereby, the first intermediate layer is formed on the surface of the solid electrolyte layer.

  Thereafter, a solvent is added to the raw material powder having the same average particle diameter as the first intermediate layer molded body and having a larger average particle diameter than the raw material powder forming the first intermediate layer on the surface of the first intermediate layer 5a. A layer slurry is prepared, and this slurry is applied onto the first intermediate layer 5a. In addition, a sheet-like molded body may be produced and laminated on the surface of the first intermediate layer 5a.

  Then, baking is performed at 1250 to 1350 ° C., which is lower than the co-firing temperature, to form the second intermediate layer 5b on the first intermediate layer 5a as shown in FIG. 1B.

Furthermore, a slurry containing an oxygen electrode layer material (for example, LaSrCoO ₃ -based oxide powder), a solvent and a pore-increasing agent was applied on the intermediate layer 5 by dipping or the like, and 1000-1300
By baking at 2 degreeC for 2 to 6 hours, the fuel cell 10 of this form of the structure shown in FIG. 1 can be manufactured. In addition, it is preferable that the fuel cell 10 thereafter causes hydrogen gas to flow therein to perform reduction treatment of 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.

  Here, the raw material powder of the first intermediate layer formed body is as small as an average particle size of 0.1 to 0.3 μm, the firing temperature of the first intermediate layer formed body is lowered to 1400 to 1485 ° C., and the firing time is increased. Is shortened to 1-2 hours. Thereby, the crystal grains in the sintered body constituting the first intermediate layer 5a are small and a large grain boundary exists, and Zr constituting the solid electrolyte layer 4 diffuses in the grain boundary, so that Zr diffuses. Many formed grain boundaries can be formed. Therefore, when forming the oxygen electrode layer 6 or during power generation, Sr constituting the oxygen electrode layer 6 diffuses to the solid electrolyte layer 4 side, and the grain boundary of the first intermediate layer 5a diffuses to the solid electrolyte layer 4 side. The columnar Sr zirconate 9a is preferentially generated at the grain boundary of the first intermediate layer 5a, and no layered Sr zirconate is generated or generated between the first intermediate layer 5a and the solid electrolyte layer 4. Even if it is very thin Sr zirconate, the electrical resistance between the solid electrolyte layer 4a and the oxygen electrode layer 6 can be reduced, and the power generation performance can be improved.

  Conventionally, since the grain boundaries of the dense first intermediate layer 5a are small, Zr of the solid electrolyte layer 4 cannot be diffused, but Sr of the oxygen electrode layer 6 diffuses through the small grain boundaries of the first intermediate layer 5a, and solids Although a layered Sr zirconate was generated between the electrolyte layer 4 and the first intermediate layer 5a, in this embodiment, since the grain boundaries of the dense first intermediate layer 5a are large, the Zr of the solid electrolyte layer 4 is The columnar Sr zirconate 9a is preferentially formed rather than diffusing the grain boundary of the first intermediate layer 5a and generating a layered Sr zirconate between the solid electrolyte layer 4 and the first intermediate layer 5a. thinking.

  Note that Zr diffuses in the pores of the second intermediate layer 5b through the grain boundaries of the first intermediate layer 5a, and Sr zirconate 9b is also generated in the second intermediate layer 5b.

  FIG. 3 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 cross-sectional view of the fuel cell stack device 11 of (a), the portion surrounded by the broken line shown in (a) An excerpt is shown. In addition, in (b), the part corresponding to the part surrounded by the broken line shown in (a) is indicated by an arrow, and in the fuel cell 10 shown in (b), the above-described reaction prevention is shown. Some members such as the layer 5 are omitted.

  In the fuel cell stack device 11, the fuel cell stack 12 is configured by arranging the fuel cells 10 via the current collecting members 13, and the lower end of each fuel cell 10 is a fuel cell. The gas tank 16 for supplying the fuel gas to the battery cell 10 is fixed with an adhesive such as a glass sealing material. In addition, an elastically deformable conductive member 14 having a lower end fixed to the gas tank 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. Yes.

  Further, in the conductive member 14 shown in FIG. 3, 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 device 11 of the present embodiment, the fuel cell stack device 11 having good power generation performance is formed by configuring the fuel cell stack 12 using the fuel cell 10 described above. Can do.

FIG. 4 is an external perspective view showing an example of the fuel cell module 18 in which the fuel cell stack device 11 is accommodated in a storage container. The fuel cell shown in FIG. The cell stack device 11 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 gas tank 16 via the gas flow pipe 21 and supplied to the gas flow path 2 provided inside the fuel battery cell 10 via the gas tank 16. .

  FIG. 4 shows a state in which a part (front and rear surfaces) of the storage container 19 is removed and the fuel cell stack device 11 and the reformer 20 housed inside are taken out rearward. In the fuel cell module 18 shown in FIG. 4, 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. 4, the oxygen-containing gas introduction member 22 provided inside the storage container 19 is disposed between the fuel cell stacks 12 juxtaposed to the gas tank 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. Then, the temperature of the fuel cell 10 can be increased by reacting the fuel gas discharged from the gas flow path of the fuel cell 10 with the oxygen-containing gas and burning it on the upper end side of the fuel cell 10. The start-up of the fuel cell stack device 11 can be accelerated. In addition, by burning the fuel gas and the oxygen-containing gas discharged from the gas flow path of the fuel battery cell 10 on the upper end side of the fuel battery cell 10, the fuel battery cell 10 (fuel battery cell stack 12) The reformer 20 disposed above can be warmed. Thereby, the reforming reaction can be efficiently performed in the reformer 20.

  Furthermore, also in the fuel cell module 18 of this embodiment, since the fuel cell stack device 11 described above is accommodated in the storage container 19, the fuel cell module 18 having good power generation performance can be obtained.

  FIG. 5 is an exploded perspective view showing an example of a fuel cell device in which the fuel cell module 18 shown in FIG. 4 and an auxiliary machine for operating the fuel cell stack device 11 are housed in an outer case. . In FIG. 5, a part of the configuration is omitted.

  The fuel cell device 23 shown in FIG. 5 has a module housing chamber in which an outer case made up of struts 24 and an outer plate 25 is divided into upper and lower portions by a partition plate 26 and the upper side thereof houses the fuel cell module 18 described above. 27, the lower side is configured as an auxiliary equipment storage chamber 28 for storing auxiliary equipment for operating the fuel cell module 18. In addition, auxiliary machines stored in the auxiliary machine storage chamber 28 are not shown.

  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 fuel cell device 18 that can improve the reliability is housed in the module housing chamber 27, so that the fuel cell device has good power generation performance. 23.

As mentioned above, this invention is not limited to the above-mentioned embodiment, A various change, improvement, etc. are possible in the range which does not deviate from the summary of this invention.

  In the above embodiment, the hollow plate type solid oxide fuel cell has been described. However, it may be a cylindrical solid electrolyte fuel cell or a flat plate fuel cell. .

First, a NiO powder having an average particle size of 0.5 μm and a Y ₂ O ₃ powder having an average particle size of 0.9 μm are mixed, and a clay prepared with an organic binder and a solvent is molded by an extrusion molding method and dried. A conductive support molded body was prepared by degreasing.

Next, using a slurry obtained by mixing a ZrO ₂ powder (solid electrolyte layer raw material powder) having a particle diameter of 0.8 μm by solid micro-solution method in which 8 mol% of Y is 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.

Next, a fuel electrode layer slurry is prepared by mixing a NiO powder having an average particle size of 0.5 μm, a ZrO ₂ powder in which Y is dissolved, and a solvent, and applying the slurry onto a solid electrolyte layer sheet. 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, the slurry for the first intermediate layer prepared by adding a solvent to the raw material powder having an average particle size shown in Table 1 and mixing the slurry on the solid electrolyte layer calcined body of the obtained laminated calcined body, It apply | coated by the screen printing method and produced the 1st intermediate | middle layer molded object. The average particle diameter of the raw material powder was determined by the microtrack method (laser diffraction / scattering method).

_{Subsequently,} the _{La (Mg 0.3 Cr 0.7) 0.96} O 3, to prepare a slurry of a mixture of organic binder and a solvent, to prepare a interconnector sheet.

  A raw material composed of Ni and YSZ was mixed and dried, and a solvent was mixed therewith to prepare an adhesion layer slurry. The adjusted slurry for the adhesion layer was applied to a portion of the conductive support where the fuel electrode layer (and the solid electrolyte layer) was not formed (the portion where the conductive support was exposed), and the adhesion layer formed body was laminated. An interconnector sheet was laminated on the adhesion layer molded body.

  Subsequently, the above-mentioned laminated molded body was subjected to binder removal treatment, and fired in the atmosphere at the temperature shown in Table 1 for the time shown in Table 1, thereby forming the first intermediate layer having the porosity and average thickness shown in Table 1.

  After that, a slurry for the second intermediate layer prepared by adding a solvent to the raw material powder having an average particle diameter shown in Table 2 and mixing the mixture is applied onto the first intermediate layer to produce a second intermediate layer molded body. Then, baking was carried out in the atmosphere at the temperature shown in Table 2 for the time shown in Table 2, and the second intermediate layer having the porosity and average thickness shown in Table 2 was formed.

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. The oxygen electrode layer formed body was formed by spray coating, and baked at 1100 ° C. for 4 hours to form an oxygen electrode layer. Thus, the fuel cell shown in FIG. 1 was produced.

About the porosity of the 1st, 2nd intermediate | middle layer, it calculated | required using the image-analysis apparatus from the SEM photograph of arbitrary cross sections, and it described in Table 1,2.

  Sample No. It is confirmed by SEM that the columnar Sr zirconate extends from the solid electrolyte layer side toward the oxygen electrode layer side and Sr zirconate is formed on the pore surface of the second intermediate layer for the first intermediate layers 1-6. did. Further, no layered Sr zirconate was formed between the first intermediate layer and the solid electrolyte layer.

  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. 24%, the thickness of the oxygen electrode layer was 50 μm, the open porosity was 40%, and the relative density of the solid electrolyte layer was 97%.

  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.

  The fuel gas is circulated through the fuel gas flow path of the fuel cell, the air is circulated outside the fuel cell, the fuel cell is heated to 750 ° C. using an electric furnace, and a power generation test is conducted. The power density was measured. The results are shown in Table 2.

From the results in Tables 1 and 2, sample No. 1 to 6, columnar Sr zirconate extends from the solid electrolyte layer side to the oxygen electrode layer side in the first intermediate layer, and a layered Sr zirconate is formed between the first intermediate layer and the solid electrolyte layer. The power density was as high as 0.24 W / cm ² or higher. In contrast, sample no. In No. 7, columnar Sr zirconate was not formed in the first intermediate layer, and the power density was as low as 0.1 W / cm ² .

3: Fuel electrode layer 4: Solid electrolyte layer 5: Intermediate layer 5a: First intermediate layer 5b: Second intermediate layer 6: Oxygen electrode layer 8: Interconnector 9a: Columnar Sr zirconate 9b: Sr zirconate 11: Fuel cell stack Device 18: Fuel cell module 23: Fuel cell device

Claims (4)

A solid electrolyte layer made of zirconia, a fuel electrode layer provided on one side of the solid electrolyte layer, an oxygen electrode layer made of a perovskite complex oxide containing La and Sr provided on the other side, and the solid Between the electrolyte layer and the oxygen electrode layer , made of ceria, a dense first intermediate layer provided on the solid electrolyte layer side, and a porous second layer provided on the oxygen electrode layer side An intermediate layer, and
A plurality of columnar Sr zirconates extending from the solid electrolyte layer side to the oxygen electrode layer side are provided at the crystal grain boundary of the first intermediate layer, which is a crystal grain boundary smaller than the crystal grain boundary of the second intermediate layer . A solid oxide fuel cell characterized by the above. 2. The solid oxide fuel cell according to claim 1, wherein Sr zirconate is provided on a pore surface of the second intermediate layer . A cell stack comprising a plurality of the solid oxide fuel cells according to claim 1 or 2 and electrically connecting the plurality of solid oxide fuel cells. apparatus. A fuel cell module comprising a plurality of solid oxide fuel cells according to claim 1 or 2 in a storage container.