JPWO2016208449A1 - Solid oxide fuel cell - Google Patents

Abstract

The cathodes CT <b> 1 to CT <b> 4 are made of conductive ceramics and are arranged on the lower surface side of the electrolyte layer 123. The anodes AN1 to AN4 are arranged on the upper surface side of the electrolyte layer 123. The separator SP1 is disposed at a position sandwiching the cathodes CT1 to CT4 together with the electrolyte layer 123, and has via holes VHa, VHa,... Reaching the cathodes CT1 to CT4. Interconnectors CNa, CNa,... Are provided in via holes VHa, VHa,... And connected to cathodes CT1 to CT4. The interconnector CNa includes a connector layer CL1a made of conductive ceramics different from the type of conductive ceramics forming the cathodes CT1 to CT4, and a connector made of metal and disposed at a position closer to the cathodes CT1 to CT4 than the connector layer CL1a. Layer CL2a.

Description

  The present invention relates to a solid oxide fuel cell, and in particular, a solid oxide comprising a plurality of fuel cells each having a surface electrode exposed on one main surface and the other main surface facing in the stacking direction. The present invention relates to a fuel cell.

  An example of this type of fuel cell is disclosed in Patent Document 1. According to this document, an intermediate film made of conductive ceramic forms part of an interconnector. The portion of the interconnector closer to the separator than the intermediate film contains at least one selected from the group consisting of Ag, Pd, Pt, Fe, Co, Cu, Ru, Rh, Re, and Au. On the other hand, the portion of the interconnector closer to the fuel electrode than the intermediate film is made of the same material as the fuel electrode.

  Specifically, the portion on the fuel electrode side includes nickel oxide, yttrium oxide stabilized zirconia containing Ni (yttria stabilized zirconia (YSZ)), calcium oxide stabilized zirconia containing Ni, scandium oxide stabilized zirconia containing Ni. (Scandia stabilized zirconia (ScSZ)), cerium oxide stabilized zirconia containing Ni, titanium oxide containing Ni, alumina containing Ni, magnesia containing Ni, yttria containing Ni, niobium oxide containing Ni or oxidation containing Ni Made of tantalum or the like.

International Publication No. 2012/133263 (see FIG. 12, paragraphs 0036 and 0069)

  However, when the intermediate film is directly connected to the portion on the fuel electrode side, each constituent element diffuses to each other in the connecting portion, and a deviation from a predetermined composition is present in both the intermediate film and the portion on the fuel electrode side. Occur. Such a shift causes a decrease in conductivity or activity.

  Further, when the intermediate film is directly connected to the portion on the fuel electrode side, the conductive ceramics forming the intermediate film is exposed to a reducing atmosphere during power generation. As a result, cell characteristics deteriorate due to reductive decomposition of the conductive ceramic.

  Therefore, a main object of the present invention is to provide a solid oxide fuel cell capable of suppressing a decrease in conductivity or activity.

  Another object of the present invention is to provide a solid oxide fuel cell capable of suppressing deterioration of cell characteristics resulting from reductive decomposition of conductive ceramics.

  The solid oxide fuel cell of the present invention is disposed at an electrolyte layer, a position on one main surface side of the electrolyte layer, a first electrode made of conductive ceramics, and a position on the other main surface side of the electrolyte layer. And a second electrode, a separator having a via hole reaching the first electrode, and an interconnector provided in the via hole and connected to the first electrode. The interconnector includes a first connector layer made of conductive ceramics different from the type of conductive ceramics forming the first electrode, and a second connector made of metal and disposed at a position closer to the first electrode than the first connector layer. Including a connector layer.

  The type of the conductive ceramic forming the first connector layer is different from the type of the conductive ceramic forming the first electrode. Based on this, a second connector layer made of metal is disposed between different kinds of conductive ceramics. Thereby, element diffusion between different kinds of conductive ceramics is suppressed, and as a result, a decrease in conductivity or activity is suppressed.

  Preferably, the interconnector further includes a third connector layer made of a conductive ceramic of the same type as that of the conductive ceramic forming the first electrode, and disposed at a position closer to the first electrode than the second connector layer. .

  By disposing the third connector layer made of the same type of conductive ceramic as the type of the conductive ceramic forming the first electrode at a position closer to the first electrode than the second connector layer, the second connector layer can be freely arranged. The degree can be increased.

  The solid oxide fuel cell according to the present invention includes an electrolyte layer, a fuel electrode made of cermet disposed at a position on one main surface side of the electrolyte layer, and an air electrode disposed at a position on the other main surface side of the electrolyte layer. And a separator having a via hole reaching the fuel electrode in cooperation with the electrolyte layer, and an interconnector provided in the via hole and connected to the fuel electrode. And a first connector layer made of conductive ceramics and a second connector layer made of metal and disposed at a position closer to the fuel electrode than the first connector layer.

  The concern that the conductive ceramic forming the first connector layer is exposed to the reducing atmosphere during power generation is reduced, and deterioration of cell characteristics due to reductive decomposition of the conductive ceramic can be suppressed.

  Preferably, the interconnector is made of the same type of cermet as the cermet forming the fuel electrode, and further includes a third connector layer disposed at a position closer to the fuel electrode than the second connector layer.

  By disposing the third connector layer made of the same type of cermet as the cermet forming the fuel electrode at a position closer to the fuel electrode than the second connector layer, the degree of freedom of the arrangement of the second connector layer can be increased.

  Preferably, the cermet material comprises nickel oxide, yttrium oxide stabilized zirconia containing Ni, calcium oxide stabilized zirconia containing Ni, scandium oxide stabilized zirconia containing Ni, cerium oxide stabilized zirconia containing Ni, Ni Titanium oxide, alumina containing Ni, magnesia containing Ni, yttria containing Ni, niobium oxide containing Ni, or tantalum oxide containing Ni.

The material of the separator is, for example, zirconia (ZrO ₂ ) (yttria stabilized zirconia: YSZ) stabilized with yttria (Y ₂ O ₃ ) with an addition amount of 3 mol%, or ceria (CeO ₂ ) with an addition amount of 12 mol%. ) Stabilized zirconia (ZrO ₂ ) (ceria stabilized zirconia: CeSZ). By using the cermet material as described above, the thermal expansion coefficient is close between the cermet and the separator. As a result, the occurrence of cracks and delamination due to the difference in thermal expansion is suppressed, and consequently the deterioration of the output characteristics is suppressed.

  Preferably, the thickness of the second connector layer is 30 μm or less.

  By setting the thickness of the second connector layer to 30 μm or less, stress due to the difference between the thermal expansion amount of the second connector layer and the thermal expansion amount of the separator is suppressed. This reduces the concern that the cell is physically destroyed during the heat cycle due to cracks and delamination.

  Preferably, the metal forming the second connector layer includes at least one of Ag, Pd, Pt, Fe, Cr, Co, Cu, Ru, Rh, Re, and Au.

  Element diffusion between different kinds of conductive ceramics is suppressed, and as a result, a decrease in conductivity or activity is suppressed.

  Preferably, the conductive ceramic material is ABO3 (where A is at least one of Ca, Sr, Ba, La, Pr and Y, and B is Ni, Ti, V, Cr, Mn, Fe, A perovskite oxide represented by at least one of Co, Mo, Ru, Rh, Pd, and Re).

The material of the separator is, for example, zirconia (ZrO ₂ ) (yttria stabilized zirconia: YSZ) stabilized with yttria (Y ₂ O ₃ ) with an addition amount of 3 mol%, or ceria (CeO ₂ ) with an addition amount of 12 mol%. ) Stabilized zirconia (ZrO ₂ ) (ceria stabilized zirconia: CeSZ). By using the above-mentioned conductive ceramic material, the thermal expansion coefficient is close between the conductive ceramic and the separator. As a result, the occurrence of cracks and delamination due to the difference in thermal expansion is suppressed, and consequently the deterioration of the output characteristics is suppressed.

  According to this invention, it is possible to suppress a decrease in conductivity or activity, or it is possible to suppress deterioration in cell characteristics due to reductive decomposition of conductive ceramics.

  The above object, other objects, features and advantages of the present invention will become more apparent from the following detailed description of embodiments with reference to the drawings.

It is a perspective view which shows the external appearance of the fuel cell unit of this Example. It is a perspective view which shows an example of the state which decomposed | disassembled some fuel cell units of this Example, and was seen from diagonally upward. It is a perspective view which shows an example of the state which decomposed | disassembled the other part of the fuel cell unit of this Example, and was seen from diagonally upward. It is a perspective view which shows an example of the state which decomposed | disassembled and looked at the fuel cell of this Example from diagonally upward. It is a perspective view which shows an example of the state which looked at the fuel electrode side conductor layer which comprises the fuel battery cell of this Example from diagonally downward. It is sectional drawing which shows the principal part cross section of the fuel cell of this Example. It is sectional drawing which shows the principal part cross section of the fuel cell of another Example. It is sectional drawing which shows the principal part cross section of the fuel cell of other Examples. Furthermore, it is sectional drawing which shows the principal part cross section of the fuel cell of another Example. It is sectional drawing which shows the principal part cross section of the fuel cell of another Example. It is sectional drawing which shows the principal part cross section of the fuel cell of other Examples. Furthermore, it is sectional drawing which shows the principal part cross section of the fuel cell of another Example.

  1 to 5, the fuel cell unit 10 is a solid oxide fuel cell unit, and includes two fuel cells 20 a and 20 b and a single conductive layer 22. The fuel cells 20a, 20b and the conductive layer 22 are deposited so that the side surfaces thereof are flush with each other (however, it is not essential that they are flush with each other), thereby forming the flat fuel cell stack 12. The

  In this embodiment, the X axis, the Y axis, and the Z axis are assigned to the width direction, the depth direction, and the height direction of the rectangular parallelepiped forming the fuel cell stack 12, respectively.

  As shown in FIG. 4, each of the fuel cells 20a and 20b is formed by laminating an air electrode side conductor layer 121, an air electrode layer 122, an electrolyte layer 123, a fuel electrode layer 124, and a fuel electrode side conductor layer 125 in this order. It becomes.

  Via holes VHa, VHa,... Reaching the lower surface are formed on the upper surface of the air electrode side conductor layer 121, and via holes VHf, VHf,. .. Are embedded in the via holes VHa, VHa,..., And the interconnectors CNf, CNf,... Are embedded in the via holes VHf, VHf,.

  In the air electrode layer 122, cathodes CT1 to CT4 are formed at positions overlapping the interconnectors CNa, CNa,... As viewed from the Z-axis direction. In the fuel electrode layer 124, anodes AN1 to AN4 are formed at positions overlapping the interconnectors CNf, CNf,... As viewed from the Z-axis direction.

  In each of the fuel cells 20a and 20b, manifolds MFf1 and MFf2 for propagating the fuel electrode gas in the Z-axis direction are formed, and further, manifolds MFa1 and MFa2 for propagating the air electrode gas in the Z-axis direction are formed.

  When viewed from the Z-axis direction, the manifolds MFf1 and MFf2 are formed on straight lines extending in the Y-axis direction from the center of the upper surface of each of the fuel cells 20a and 20b, and the manifolds MFa1 and MFa2 are each of the fuel cells 20a and 20b. Is formed on a straight line extending in the X-axis direction with the center of the upper surface of the substrate as the base point.

  More specifically, the manifold MFf1 is disposed on the positive side in the Y axis direction from the center of the upper surface, and the manifold MFf2 is disposed on the negative side in the Y axis direction from the center of the upper surface. The manifold MFa1 is arranged on the positive side in the X-axis direction from the center of the upper surface, and the manifold MFa2 is arranged on the negative side in the X-axis direction from the center of the upper surface.

  Therefore, the interconnectors CNf, CNf,... On the anodes AN1 to AN4 side are divided into four parts based on the manifolds MFf1, MFf2, MFa1, and MFa2. Similarly, the interconnectors CNa, CNa,... On the cathodes CT1 to CT4 side are also divided into four parts based on the manifolds MFf1, MFf2, MFa1, and MFa2.

  The air electrode side conductor layer 121 uses the separator SP1 as a base material, the air electrode layer 122 uses the separator SP2 as a base material, the electrolyte layer 123 uses the electrolyte EL as a base material, and the fuel electrode layer 124 uses the separator SP4 as a base material. The pole-side conductor layer 125 uses the separator SP5 as a base material. The separator SP2 is composed of partial separators SP21 to SP23, and the separator SP4 is composed of partial separators SP41 to SP43.

  In addition to the above-described interconnectors CNa, CNa,..., The separator SP1 that forms the air electrode side conductor layer 121 includes two through-holes that form each of the manifolds MFf1, MFf2, MFa1, and MFa2, each in the Y-axis direction. Four air electrode gas flow paths GRa, GRa,... Extending and arranged in the X-axis direction are provided. The total number of through holes is eight, and all of the through holes form a perfect circle when viewed from the Z-axis direction.

  Moreover, all four air electrode gas flow paths GRa, GRa,... Are formed on the upper surface of the separator SP1. Of these, the two air electrode gas flow paths GRa and GRa respectively overlap with two through holes forming the manifold MFa1. The remaining two air electrode gas flow paths GRa and GRa respectively overlap with the two through holes forming the manifold MFa2.

  The interconnectors CNa, CNa,... Are provided at positions that avoid these through holes and the air electrode gas flow paths GRa, GRa,. Further, the interconnectors CNa, CNa,... Extend in the Z-axis direction, and one end and the other end thereof are exposed on the upper surface and the lower surface of the separator SP1, respectively.

  In addition to the above-described interconnectors CNf, CNf,..., The separator SP5 forming the fuel electrode side conductor layer 125 also has two through-holes forming each of the manifolds MFf1, MFf2, MFa1, and MFa2, and each in the X-axis direction. Four fuel electrode gas passages GRf, GRf,... Extending and arranged in the Y-axis direction are provided. The total number of through holes is eight, and all the through holes form a perfect circle when viewed from the Z-axis direction.

  Moreover, as shown in FIG. 5, all four fuel electrode gas flow paths GRf, GRf,... Are formed on the lower surface of the separator SP5. Of these, the two fuel electrode gas flow paths GRf and GRf respectively overlap the two through holes forming the manifold MFf1. The remaining two fuel electrode gas flow paths GRf and GRf respectively overlap with the two through holes forming the manifold MFf2.

  The interconnectors CNf, CNf,... Are provided at positions that avoid these through holes and the fuel electrode gas flow paths GRf, GRf,. Further, the interconnectors CNf, CNf,... Extend in the Z-axis direction, and one end and the other end thereof are exposed on the upper surface and the lower surface of the separator SP5, respectively.

  In the air electrode layer 122 shown in FIG. 4, the partial separators SP21 to SP23 have a common thickness and are formed in a stick shape. The partial separator SP21 extends in the Y-axis direction at the position of the positive end in the X-axis direction, the partial separator SP22 extends in the Y-axis direction at the center in the X-axis direction, and the partial separator SP23 is the negative end in the X-axis direction. The position of the part extends in the Y-axis direction.

  The width of the partial separator SP21 matches the width of the partial separator SP23, and the width of the partial separator SP22 is approximately twice the width of each of the partial separators SP21 and SP23. The partial separator SP22 is formed with two through holes that form the manifolds MFf1 and MFf2. Each through-hole is rectangular when viewed from the Z-axis direction, and its long side extends in the Y-axis direction.

  In a region sandwiched between the partial separators SP21 and SP22, two plate-like cathodes CT1 and CT4 are provided side by side in the Y-axis direction. Further, two plate-like cathodes CT2 and CT3 are provided side by side in the Y-axis direction in a region sandwiched between the partial separators SP22 and SP23. At this time, the cathodes CT1 and CT2 are arranged on the positive side in the Y-axis direction, and the cathodes CT3 and CT4 are arranged on the negative side in the Y-axis direction.

  Each of the cathodes CT1 to CT4 has the same thickness as that of the partial separators SP21 to SP23, and has a rectangular shape when viewed from the Z-axis direction. Each side of the rectangle extends in the X-axis direction or the Y-axis direction, and the length of the side extending in the Y-axis direction is less than ½ of the length of each of the partial separators SP21 to SP23. Further, the side surface facing the positive side in the Y-axis direction is flush with the cathodes CT1 and CT2 and the partial separators SP21 to SP23. Similarly, the side surface facing the negative side in the Y-axis direction is flush with the cathodes CT3, CT4 and the partial separators SP21 to SP23.

  Therefore, a rectangular through-hole is formed between the cathodes CT1 and CT4 as viewed from the Z-axis direction, and a rectangular through-hole is also formed between the cathodes CT2 and CT3 as viewed from the Z-axis direction. For any rectangle, the long side extends along the X axis and the short side extends along the Y axis. The two through holes formed in this way form manifolds MFa1 and MFa2.

  In the fuel electrode layer 124, the partial separators SP41 to SP43 have a common thickness and are formed in a stick shape. The partial separator SP41 extends in the X-axis direction at the position of the positive end in the Y-axis direction, the partial separator SP42 extends in the X-axis direction at the center in the Y-axis direction, and the partial separator SP43 is the negative end in the Y-axis direction. The position of the part extends in the X-axis direction.

  The width of the partial separator SP41 matches the width of the partial separator SP43, and the width of the partial separator SP42 is approximately twice the width of each of the partial separators SP41 and SP43. The partial separator SP42 is formed with two through holes that form the manifolds MFa1 and MFa2. Each through-hole is rectangular when viewed from the Z-axis direction, and its long side extends in the X-axis direction.

  In a region sandwiched between the partial separators SP41 and SP42, two plate-like anodes AN1 and AN2 are provided side by side in the X-axis direction. Further, two plate-like anodes AN3 and AN4 are provided side by side in the X-axis direction in a region sandwiched between the partial separators SP42 and SP43. At this time, the anodes AN1 and AN4 are arranged on the positive side in the X-axis direction, and the anodes AN2 and AN3 are arranged on the negative side in the X-axis direction.

  Any of the anodes AN1 to AN4 has the same thickness as the partial separators SP41 to SP43, and has a rectangular shape when viewed from the Z-axis direction. Each side of the rectangle extends in the X-axis direction or the Y-axis direction, and the length of the side extending in the X-axis direction is less than ½ of the length of each of the partial separators SP41 to SP43. Further, the side surface facing the positive side in the X-axis direction is flush with the anodes AN1, AN4 and the partial separators SP41 to SP43. Similarly, the side surface facing the negative side in the X-axis direction is flush with the anodes AN3 and AN4 and the partial separators SP41 to SP43.

  Accordingly, a rectangular through-hole is formed between the anodes AN1 and AN2 when viewed from the Z-axis direction, and a rectangular through-hole is also formed between the anodes AN3 and AN4 when viewed from the Z-axis direction. In any rectangle, the long side extends along the Y axis, and the short side extends along the X axis. The two through holes formed in this way form manifolds MFf1 and MFf2.

  The electrolyte layer 123 is formed by forming, in the electrolyte EL, four through holes that respectively form manifolds MFf1, MFf2, MFa1, and MFa2. All the through holes are rectangular when viewed from the Z-axis direction. However, the long side of the rectangle forming each of the manifolds MFf1 and MFf2 extends along the Y axis, while the long side of the rectangle forming each of the manifolds MFa1 and MFa2 extends along the X axis. The upper surfaces of the cathodes CT1 to CT4 provided on the air electrode layer 122 are in surface contact with the lower surface of the electrolyte layer 123, and the lower surfaces of the anodes AN1 to AN4 provided on the fuel electrode layer 124 are in surface contact with the upper surface of the electrolyte layer 123.

  Returning to FIG. 2, the current collecting layer 16a is formed by four small current collecting plates 161a to 164a and a single spacer 18a. Each of the small current collectors 161a to 164a is made of a metal that relaxes the thermal stress of the fuel cells 20a and 20b. Moreover, the area of the upper surface or lower surface of each of the small current collectors 161a to 164a is slightly less than ¼ of the area of the upper surface or lower surface of the fuel cell 20a. Furthermore, the thicknesses of the small current collectors 161a to 164a are the same.

  The small current collecting plate 161a is arranged at a position on the X axis direction positive side and the Y axis direction positive side of the upper surface of the fuel cell 20a so that the lower surface thereof faces a part of the interconnectors CNf, CNf,. The The small current collecting plate 162a is positioned at the X axis direction negative side and the Y axis direction positive side of the upper surface of the fuel cell 20a so that the lower surface of the small current collecting plate 162a faces another part of the interconnectors CNf, CNf,. Arranged.

  The small current collecting plate 163a is positioned at the X axis direction negative side and the Y axis direction negative side of the upper surface of the fuel cell 20a so that the lower surface of the small current collecting plate 163a faces the other part of the interconnectors CNf, CNf,. Arranged. The small current collecting plate 164a is positioned on the X axis direction positive side and the Y axis direction negative side of the upper surface of the fuel cell 20a so that the lower surface of the small current collecting plate 164a faces the other part of the interconnectors CNf, CNf,. Arranged.

  Thus, the small current collectors 161a to 164a are electrically connected to the interconnectors CNf, CNf,.

  The spacer 18a has the same thickness as the small current collecting plates 161a to 164a, and is disposed at a position where the small current collecting plates 161a to 164a are missing. Since the small current collecting plates 161a to 164a are arranged as described above, the upper surface or the lower surface of each spacer 18a forms a cross. In addition, the thickness of the spacer 18a does not necessarily need to be the same as the thickness of the small current collectors 161a to 164a. This is because the difference in thickness can be adjusted by a conductive material or a sealing material.

  Further, the current collecting layer 16b shown in FIG. 3 is formed by four small current collecting plates 161b to 164b and a single spacer 18b. Each of the small current collectors 161b to 164b is also made of a metal that relaxes the thermal stress of the fuel cells 20a and 20b. In addition, the area of the upper surface or the lower surface of each of the small current collectors 161b to 164b is slightly less than 1/4 of the area of the upper surface or the lower surface of the fuel cell 20b. Further, the thicknesses of the small current collectors 161b to 164b are equal to each other.

  The small current collecting plate 161b is arranged at a position on the positive side in the X-axis direction and on the positive side in the Y-axis direction of the lower surface of the fuel cell 20b so that the upper surface thereof faces a part of the interconnectors CNa, CNa,. The The small current collecting plate 162b is positioned at the negative side in the X-axis direction and the positive side in the Y-axis direction on the lower surface of the fuel cell 20b so that the upper surface thereof faces the other part of the interconnectors CNa, CNa,. Arranged.

  The small current collecting plate 163b is positioned at the X-axis direction negative side and the Y-axis direction negative side of the lower surface of the fuel cell 20b so that the upper surface thereof faces the other part of the interconnectors CNa, CNa,. Arranged. The small current collecting plate 164b is positioned on the X axis direction positive side and the Y axis direction negative side of the lower surface of the fuel cell 20b so that the upper surface of the small current collecting plate 164b faces a further part of the interconnectors CNa, CNa,. Arranged.

  Thus, the small current collectors 161b to 164b are electrically connected to the interconnectors CNa, CNa,.

  The spacer 18b has the same thickness as the small current collecting plates 161b to 164b, and is disposed at a position where the small current collecting plates 161b to 164b are missing. Since the small current collectors 161b to 164b are arranged as described above, the upper surface or the lower surface of each spacer 18b forms a cross.

  In addition, with respect to the spacer 18b, four through holes that respectively form the manifolds MFf1, MFf2, MFa1, and MFa2 are formed. Each through hole is rectangular when viewed from the Z-axis direction. However, the long side of the rectangle forming each of the manifolds MFf1 and MFf2 extends along the Y axis, while the long side of the rectangle forming each of the manifolds MFa1 and MFa2 extends along the X axis.

  2 has an area that substantially matches the area of the upper surface of the fuel cell stack 12, and the upper surface or lower surface of the fixing plate 14b shown in FIG. 3 has an area of the lower surface of the fuel cell stack 12. It has almost the same area.

  The fixing plate 14a is disposed on the upper surface of the current collecting layer 16a so that a part of the lower surface thereof faces the upper surface of the current collecting layer 16a. The fixing plate 14b is disposed on the lower surface of the current collecting layer 16b so that a part of the upper surface thereof faces the lower surface of the current collecting layer 16b. Here, the side surfaces of the fixing plates 14a and 14b are flush with the side surface of the fuel cell stack 12 (however, it is not essential that they be flush).

  In addition, the fixing plate 14b is provided with two through holes that form the manifolds MFf1, MFf2, MFa1, and MFa2. The total number of through holes is eight, and all of the through holes form a perfect circle when viewed from the Z-axis direction.

  The conductive layer 22 provided between the fuel cells 20a and 20b transmits the current extracted from the fuel cells 20a and 20b to the current collecting layers 16a and 16b.

  The conductive layer 22 is also formed by four small conductive plates 221 to 224 and a single spacer 24. Each of the small conductive plates 221 to 224 is also made of a metal that relieves the thermal stress of the fuel cells 20a and 20b. Further, the area of the upper surface or the lower surface of each of the small conductive plates 221 to 224 is slightly less than 1/4 of the area of the upper surface or the lower surface of the fuel cells 20a, 20b. Further, the small conductive plates 221 to 224 have the same thickness.

  The small conductive plate 221 has a top surface facing a part of the interconnectors CNa, CNa,... And a bottom surface facing a part of the interconnectors CNf, CNf,. Are arranged on the X axis direction positive side and the Y axis direction positive side. The small conductive plate 222 has an upper surface facing another part of the interconnectors CNa, CNa,... And a lower surface facing another part of the interconnectors CNf, CNf,. And 20b between the X axis direction negative side and the Y axis direction positive side.

  The small conductive plate 223 has an upper surface facing the other part of the interconnectors CNa, CNa,... And a lower surface facing the other part of the interconnectors CNf, CNf,. And 20b between the X axis direction negative side and the Y axis direction negative side. The small conductive plate 224 has a top surface facing another part of the interconnectors CNa, CNa,... And a bottom surface facing another part of the interconnectors CNf, CNf,. It is arranged at a position between the cells 20a and 20b on the X axis direction positive side and the Y axis direction negative side.

  The interconnectors CNa, CNa,... Provided in the fuel cell 20a are electrically connected to the interconnectors CNf, CNf,... Provided in the fuel cell 20b through the small conductive plates 221 to 224 thus arranged. Connected.

  The spacer 24 has the same thickness as the small conductive plates 221 to 224 and is disposed at a position where the small conductive plates 221 to 224 are missing. Since the small conductive plates 221 to 224 are arranged as described above, the upper surface or the lower surface of each spacer 24 forms a cross.

  The spacer 24 is also formed with four through holes that form the manifolds MFf1, MFf2, MFa1, and MFa2. Each through hole is rectangular when viewed from the Z-axis direction. However, the long side of the rectangle forming each of the manifolds MFf1 and MFf2 extends along the Y axis, while the long side of the rectangle forming each of the manifolds MFa1 and MFa2 extends along the X axis.

  The air electrode gas flowing through the manifolds MFa1 and MFa2 is discharged to the outside of the fuel cell stack 12 via the air electrode gas flow paths GRa, GRa,. Further, the fuel electrode gas flowing through the manifolds MFf1 and MFf2 is discharged to the outside of the fuel cell stack 12 via the fuel electrode gas flow paths GRf, GRf,.

When the air electrode gas flows through the manifolds MFa12, MFa22 and the air electrode gas flow paths GRa, GRa,..., The air electrode gas contacts the cathodes CT1 to CT4. Further, the fuel electrode gas contacts the anodes AN1 to AN4 when flowing through the manifolds MFf14, MFf24 and the fuel electrode gas flow paths GRf, GRf,. The air electrode gas and the fuel electrode gas undergo a chemical reaction according to the chemical formulas 1 and 2, and as a result, a positive voltage and a negative voltage appear on both surfaces of the electrolyte EL.
[Chemical 1]
1 / 2O ₂ + 2e ⁻ → O ²⁻
[Chemical formula 2]
H ₂ + O ²⁻ → H ₂ O + 2e ⁻

  A part of the air electrode gas and the fuel electrode gas is discharged to the outside of the fuel cells 20a and 20b without causing a chemical reaction. The air electrode gas is discharged through the air electrode gas flow paths GRa, GRa,..., And the fuel electrode gas is discharged through the fuel electrode gas flow paths GRf, GRf,. The discharged air electrode gas and fuel electrode gas react with each other to generate heat, thereby achieving heat independence.

The material of each of the separators SP1 to SP2 and SP4 to SP5 is, for example, zirconia (ZrO ₂ ) (yttria stabilized zirconia: YSZ) stabilized with yttria (Y ₂ O ₃ ) added in an amount of 3 mol%, or added. Zirconia (ZrO ₂ ) (ceria stabilized zirconia: CeSZ) stabilized with an amount of 12 mol% ceria (CeO ₂ ).

Each of the cathodes CT1 to CT4 is made of a conductive ceramic, more specifically, ABO ₃ or A2BO ₄ (where A is at least one of Ca, Sr, Ba, La, Pr, and Y, B is made of a perovskite oxide represented by at least one of Ni, Ti, V, Cr, Mn, Fe, Co, Mo, Ru, Rh, Pd, and Re).

  Further, each of the anodes AN1 to AN4 is made of a porous cermet, and more specifically, nickel oxide, yttrium oxide stabilized zirconia containing Ni, calcium oxide stabilized zirconia containing Ni, and scandium oxide stabilized with Ni. The materials are zirconia, cerium oxide stabilized zirconia containing Ni, titanium oxide containing Ni, alumina containing Ni, magnesia containing Ni, yttria containing Ni, niobium oxide containing Ni, and tantalum oxide containing Ni.

  Based on this, as shown in FIG. 6, each of the interconnectors CNa, CNa,... Provided in the air electrode side conductor layer 121 is formed by connector layers CL1a and CL2a stacked in the Z-axis direction. Of these, the connector layer CL1a is made of conductive ceramics, and the connector layer CL2a is made of metal. Further, the connector layer CL2a is arranged at a position closer to the cathodes CT1 to CT4 than the connector layer CL1a. More specifically, the upper surface of the connector layer CL2a is in surface contact with the lower surface of any one of the cathodes CT1 to CT4, and the lower surface of the connector layer CL2a is in surface contact with the upper surface of the connector layer CL1a.

  On the other hand, each of the interconnectors CNf, CNf,... Provided in the fuel electrode side conductor layer 125 is formed by connector layers CL0f, CL1f, and CL2f stacked in the Z-axis direction. Among these, the connector layer CL0f is made of metal, the connector layer CL1f is made of conductive ceramics, and the connector layer CL2f is made of metal. The connector layer CL2f is arranged at a position closer to the anodes AN1 to AN4 than the connector layer CL1f, and the connector layer CL1f is arranged at a position closer to the anodes AN1 to AN4 than the connector layer CL0f.

  More specifically, the lower surface of connector layer CL2f is in surface contact with the upper surface of any one of anodes AN1-AN4, the lower surface of connector layer CL1f is in surface contact with the upper surface of connector layer CL2f, and the lower surface of connector layer CL0f is the connector layer CL1f. Surface contact with the top surface of

  Strictly speaking, the separator SP1 is composed of a flat partial separator SP1a without the air electrode gas flow paths GRa, GRa,... And a partial separator SP1b divided into strips by the air electrode gas flow paths GRa, GRa,. It is formed. The connector layer CL1a is disposed across the partial separators SP1a and SP1b, and the connector layer CL2a is disposed on the partial separator SP1b.

  Similarly, strictly speaking, the separator SP5 includes a flat partial separator SP5a in which the fuel electrode gas flow paths GRf, GRf,... Do not exist, and a partial separator divided into strips by the fuel electrode gas flow paths GRf, GRf,. And SP5b. The connector layer CL0f is disposed across the partial separators SP5a and SP5b, and the connector layers CL1f and CL2f are disposed on the partial separator SP5b.

More specifically, the conductive ceramic forming each of the connector layers CL1a and CL1f is ABO ₃ or A ₂ BO ₄ (where A is at least one of Ca, Sr, Ba, La, Pr and Y) , B is made of a perovskite oxide represented by Ni, Ti, V, Cr, Mn, Fe, Co, Mo, Ru, Rh, Pd, and Re). However, the type of conductive ceramic forming the connector layer CL1a is different from the type of conductive ceramic forming the cathodes CT1 to CT4 (the meaning of different materials will be described later).

  The thickness of each of the connector layers CL2f and CL2a is 30 μm or less, and the metal forming each of the connector layers CL2f and CL2a is Ag, Pd, Pt, Fe, Cr, Co, Cu, Ru, Rh, Re, and Au. Including at least one. The metal forming the connector layer CL0f also includes at least one of Ag, Pd, Pt, Fe, Cr, Co, Cu, Ru, Rh, Re, and Au.

  Thus, paying attention to the cathodes CT1 to CT4, the type of conductive ceramic forming the connector layer CL1a is different from the type of conductive ceramic forming the cathodes CT1 to CT4. Based on this, a connector layer CL2a made of metal is disposed between different kinds of conductive ceramics. Thereby, element diffusion between different kinds of conductive ceramics is suppressed, and as a result, a decrease in conductivity or catalytic activity is suppressed.

  When attention is paid to the anodes AN1 to AN4, the connector layer CL2f made of metal is arranged between the connector layer CL1f made of conductive ceramics and the anodes AN1 to AN4 made of porous cermet. As a result, the concern that the conductive ceramics forming the connector layer CL1f are exposed to a reducing atmosphere during power generation is reduced, and deterioration of cell characteristics due to reductive decomposition of the conductive ceramics can be suppressed.

  Further, by setting the thickness of each of the connector layers CL2a and CL2f to 30 μm or less, the stress due to the difference between the thermal expansion amounts of the connector layers CL2a and CL2f and the thermal expansion amounts of the separators SP1 and SP5 is suppressed. This reduces the concern that the cell is physically destroyed during the heat cycle due to cracks and delamination.

For reference, Table 1 shows the relationship between the via thickness (= the thickness of each of the connector layers CL2a and CL2f) obtained by the experiment and the occurrence rate of cracks. According to Table 1, the crack generation rate during the heat cycle is 98% for a via thickness of 200 μm, 90% for a via thickness of 120 μm, and 40% for a via thickness of 60 μm. It was. On the other hand, when the via thickness was 30 μm or less, the crack occurrence rate during the heat cycle was 0%. This shows that the via thickness is preferably 30 μm or less.

  Further, since the metal forming the connector layer CL2a includes at least one of Ag, Pd, Pt, Fe, Cr, Co, Cu, Ru, Rh, Re, and Au, element diffusion between different types of conductive ceramics can be achieved. It is suppressed, and as a result, a decrease in conductivity or activity is suppressed.

Furthermore, the material of each of the separators SP1 and SP5 is, for example, zirconia (ZrO ₂ ) (yttria stabilized zirconia: YSZ) stabilized with yttria (Y ₂ O ₃ ) added in an amount of 3 mol%, or an added amount 12 Zirconia (ZrO ₂ ) stabilized with mol% ceria (CeO ₂ ) (ceria stabilized zirconia: CeSZ).

  Based on this, by making the materials of the cermet and the conductive ceramic as described above, the thermal expansion coefficient becomes close between the cermet or the conductive ceramic and the separator. As a result, the occurrence of cracks and delamination due to the difference in thermal expansion is suppressed, and consequently the deterioration of the output characteristics is suppressed.

  The type of the conductive ceramic material forming the connector layer CL1a is different from the type of the conductive ceramic material forming the cathodes CT1 to CT4, and the meaning of the “foreign material” is as follows.

Conductive ceramic constituting the connector layer CL1a or cathode CT1~CT4 is more _{specifically, LaSrCoO 3, LaSrCoFeO 3, MnCoO} 3, SmSrCoO 3, LaCaMnO 3, LaCaCoO 3, LaCaCoFeO 3, LaNiFeO 3, (LaSr) 2 NiO ₄ is the basic material.

However, if at least one of the A site and B site forming the chemical formula (= ABO ₃ or A ₂ BO ₄ ) comes into contact with different materials, the A site, the B sites, or the A site and the B site are changed. Spreading between each other across the bridge. At this time, due to the composition deviation of the crystal produced with a predetermined composition, the output characteristics are lowered due to the decrease in conductivity and the decrease in catalyst activity.

  The reason why the connector layer CL2a made of metal is disposed between the cathodes CT1 to CT4 and the connector layer CL1a is to suppress such a decrease in catalytic activity. Therefore, a material in which at least one of the A site and the B site is different is a “different material”.

As a material for the conductive ceramic forming the connector layer CL1a, for example, lanthanum chromite (LaCrO ₃ ), lanthanum ferrate (LaFeO ₃ ), or lanthanum strontium manganite ((LaSr) MnO ₃ ) added with an alkaline earth metal is employed. The Further, as materials for the cathodes CT1 to CT4, for example, PrCoO ₃ -based oxides, LaCoO ₃ -based oxides, LaMnO ₃ -based oxides are employed. Specific examples of the LaMnO ₃ -based oxide include La _0.8 Sr _0.2 MnO ₃ (common name: LSM) and La _0.6 Ca _0.4 MnO ₃ (common name: LCM).
[Modification]

  In the above-described embodiment, when viewed from the Z-axis direction, the outer diameter of the connector layer CL2f matches the outer diameter of the connector layer CL1f, and the outer diameter of the connector layer CL2a matches the outer diameter of the connector layer CL1a.

  However, the outer diameter of the connector layer CL2f may be larger than the outer diameter of each of the connector layers CL0f and CL1f as shown in FIG. 7, and the outer diameter of each of the connector layers CL0f and CL1f as shown in FIG. May be small. Similarly, the outer diameter of the connector layer CL2a may be larger than the outer diameter of the connector layer CL1a as shown in FIG. 9, or may be smaller than the outer diameter of the connector layer CL1a as shown in FIG.

  Furthermore, in the above-described embodiment, the lower surface of the connector layer CL2f is in surface contact with the upper surfaces of the anodes AN1 to AN4, and the upper surface of the connector layer CL2a is in surface contact with the lower surfaces of the cathodes CT1 to CT4.

  However, as shown in FIG. 11, a connector layer CL3f made of the same material as the anodes AN1 to AN4 is added to the interconnector CNf, and the connector layer CL2f is connected to the anodes AN1 to AN4 via the connector layer CL3f. May be.

  Similarly, as shown in FIG. 12, a connector layer CL3a made of the same material as the cathodes CT1 to CT4 is added to the interconnector CNa, and the connector layer CL2a is connected to the cathodes CT1 to CT4 via the connector layer CL3a. It may be.

  In the case of FIG. 11, the upper surface of the connector layer CL3f is in surface contact with the lower surface of the connector layer CL2f, and the lower surface of the connector layer CL3f is in surface contact with the upper surfaces of the anodes AN1 to AN4. In the case of FIG. 12, the lower surface of the connector layer CL3a is in surface contact with the upper surface of the connector layer CL2a, and the upper surface of the connector layer CL3a is in surface contact with the lower surfaces of the cathodes CT1 to CT4. The degree of freedom of arrangement of the connector layer CL2f is improved by adding the connector layer CL3f, and the degree of freedom of arrangement of the connector layer CL2a is improved by adding the connector layer CL3a.

  11 and 12, the outer diameter when viewed from the Z-axis direction matches between the connector layers CLf0 to CLf3 and matches between the connector layers CLa1 to CLa3. However, the outer diameter when viewed from the Z-axis direction may be different between the connector layers CLf0 to CLf3, or may be different between the connector layers CLa1 to CLa3.

  Needless to say, the configurations of the plurality of modifications described above can be combined as appropriate within a consistent range.

DESCRIPTION OF SYMBOLS 10 ... Fuel cell unit 12 ... Fuel cell stack 16a, 16b ... Current collection layer 20a, 20b ... Fuel cell 22 ... Conductive layer 121 ... Air electrode side conductor layer 122 ... Air electrode layer 123 ... Electrolyte layer 124 ... Fuel electrode layer 125 ... Fuel electrode side conductor layer SP1 to SP2, SP4 to SP5 ... Separator AN1 to AN4 ... Anode (air electrode, first electrode)
CT1 to CT4 ... cathode (air electrode, second electrode)
VHa, VFf ... via hole CNa, CNf ... interconnector CL1a, CL1f ... connector layer (first connector layer)
CL2a, CL2f ... Connector layer (second connector layer)
CL3a, CL3f ... Connector layer (third connector layer)
MFa1, MFa2, MFf1, MFf2 ... manifold

Claims (8)

An electrolyte layer;
A first electrode made of conductive ceramics, disposed at a position on one main surface side of the electrolyte layer;
A second electrode disposed at a position on the other main surface side of the electrolyte layer;
A separator that is disposed at a position sandwiching the first electrode together with the electrolyte layer and has a via hole reaching the first electrode;
An interconnector provided in the via hole and connected to the first electrode;
Have
The interconnector includes a first connector layer made of a conductive ceramic of a type different from that of the conductive ceramic forming the first electrode, and a metal made of metal and disposed at a position closer to the first electrode than the first connector layer. A solid oxide fuel cell comprising a second connector layer formed.   The interconnector is made of the same type of conductive ceramic as that of the conductive ceramic forming the first electrode, and further includes a third connector layer disposed at a position closer to the first electrode than the second connector layer. The solid oxide fuel cell according to claim 1, comprising: An electrolyte layer;
A fuel electrode made of cermet, arranged at a position on one main surface side of the electrolyte layer;
An air electrode disposed at a position on the other main surface side of the electrolyte layer;
A separator having a via hole that is disposed at a position sandwiching the fuel electrode in cooperation with the electrolyte layer and reaches the fuel electrode;
An interconnector provided in the via hole and connected to the fuel electrode;
Have
The interconnector includes a first connector layer made of conductive ceramics and a second connector layer made of metal and disposed at a position closer to the fuel electrode than the first connector layer. .   The solid interconnect according to claim 3, wherein the interconnector includes a cermet of the same type as the cermet forming the fuel electrode, and further includes a third connector layer disposed at a position closer to the fuel electrode than the second connector layer. Oxide fuel cell.   The cermet material is nickel oxide, yttrium oxide stabilized zirconia containing Ni, calcium oxide stabilized zirconia containing Ni, scandium oxide stabilized zirconia containing Ni, cerium oxide stabilized zirconia containing Ni, Ni 5. The solid oxide according to claim 3, which is titanium oxide containing Ni, alumina containing Ni, magnesia containing Ni, yttria containing Ni, niobium oxide containing Ni, or tantalum oxide containing Ni. Fuel cell.   6. The solid oxide fuel cell according to claim 1, wherein a thickness of the second connector layer is 30 μm or less.   7. The solid according to claim 1, wherein the metal forming the second connector layer includes at least one of Ag, Pd, Pt, Fe, Cr, Co, Cu, Ru, Rh, Re, and Au. Oxide fuel cell.   The conductive ceramic material is ABO3 (where A is at least one of Ca, Sr, Ba, La, Pr and Y, and B is Ni, Ti, V, Cr, Mn, Fe, Co, The solid oxide fuel cell according to any one of claims 1 to 7, which is a perovskite oxide represented by at least one of Mo, Ru, Rh, Pd, and Re.

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