JP2012114082A - Solid oxide fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To inhibit the increase of the resistance in a solid oxide fuel cell.SOLUTION: The solid oxide fuel cell comprises two or more power generating units each comprising an air electrode, a fuel electrode containing nickel, and an electrolyte layer between the air electrode and the fuel electrode; an interconnector containing a chromite-based material and electrically connecting the two or more power generating units; and an intermediate layer disposed between the interconnector and the fuel electrode and containing the chromite-based material and nickel.

Description

  The present invention relates to a solid oxide fuel cell.

  In a solid oxide fuel cell including a plurality of fuel cells having an electrolyte layer and an air electrode, an interconnector that electrically connects the fuel electrode of the fuel cell and the air electrode of another fuel cell is provided.

Conventionally, it has been proposed to provide an intermediate layer between the interconnector and the fuel electrode.
For example, Patent Document 1 discloses a support, an electrolyte layer wound around the support so as to expose a part of the support, a fuel electrode provided between the electrolyte layer and the support, and a support. A fuel cell comprising an interconnector stacked on an exposed part of the body and an intermediate film provided at the interface between the interconnector and a support is described. Further, Patent Document 1 discloses that a fuel cell is a support formed of a material in which Ni and Y ₂ O ₃ are mixed at a volume ratio of 1: 1; an inter-layer formed of La (Mg, Cr) O _3. A connector; and an intermediate layer formed of a material obtained by mixing Ni powder and CeO ₂ powder (ceria powder) containing 20 mol% of rare earth elements such as Gd.

JP 2004-253376 A

However, the present inventors have found that cracks are generated in the intermediate layer by reduction in the conventional technique. It is considered that the cracks are generated because the intermediate layer expands due to the reduction. The occurrence of cracks reduces the conductivity of the fuel cell.
In addition, a component such as ceria in the intermediate layer is solid-dissolved in the lanthanum chromite, so that a NiO aggregate layer is formed at the interface with the interconnector in the intermediate layer. Since NiO in the aggregated layer is reduced to Ni by the reduction treatment, the volume of the aggregated layer is reduced by the reduction treatment. Also by this, a crack is easily generated in the intermediate layer, and peeling is easily generated between the intermediate layer and the interconnector.
The occurrence of cracks reduces the conductivity of the fuel cell.

  An object of this invention is to suppress the fall of the electroconductivity in a fuel cell.

  A solid oxide fuel cell according to a first aspect of the present invention includes an air electrode, a fuel electrode containing nickel, and two or more power generation units each including an electrolyte layer disposed between the air electrode and the fuel electrode. An interconnector containing a chromite-based material and arranged to electrically connect two or more of the power generation units; and a chromite-based material disposed between the interconnector and the fuel electrode And an intermediate layer containing nickel.

  In the solid oxide fuel cell, the fuel electrode contains Ni, the interconnector contains a chromite material, and the intermediate layer contains Ni and a chromite material.

It is a cross-sectional view showing one embodiment of a horizontal stripe solid oxide fuel cell. It is the II-II arrow longitudinal cross-sectional view of the horizontal stripe type solid oxide fuel cell of FIG. It is sectional drawing which shows the jig | tool used for a denseness evaluation test.

<1. First Embodiment>
As shown in FIGS. 1 and 2, a horizontal stripe solid oxide fuel cell (hereinafter simply referred to as “fuel cell”) 1 according to this embodiment includes a support substrate 2, a fuel electrode 3, an electrolyte layer 4, a reaction. A prevention layer 5, an air electrode 6, an interconnector 7, and a current collection layer 8 are provided. The fuel cell 1 includes a power generation unit 10. In FIG. 1, the current collecting layer 8 is not shown for convenience of explanation.

The support substrate 2 is flat and has a shape that is long in one direction (z-axis direction). The support substrate 2 is made of a porous material. The support substrate 2 may contain nickel. More specifically, the support substrate 2 may contain Ni—Y ₂ O ₃ (nickel-yttria) as a main component. Nickel may be an oxide (NiO), but NiO may be reduced to Ni by hydrogen gas during power generation.

  In this specification, “containing as a main component” may mean containing 50% by weight or more of the component, and containing 60% by weight or more, 80% by weight or more, or 90% by weight or more. There may be. Further, “containing as a main component” also includes a case where only the component is included.

  As shown in FIGS. 1 and 2, a flow path 21 is provided inside the support substrate 2. The flow path 21 extends along the longitudinal direction (z-axis direction) of the support substrate 2. During power generation, the fuel gas is caused to flow through the flow path 21, and the fuel gas is supplied to the later-described fuel electrode 3 through the holes of the support substrate 2.

  The fuel electrode 3 is provided on the support substrate 2. A plurality of fuel electrodes 3 are arranged on a single support substrate 2 so as to be aligned in the longitudinal direction (z-axis direction) of the support substrate 2. That is, a gap is provided between the adjacent fuel electrodes 3 in the longitudinal direction (z-axis direction) of the support substrate 2.

The fuel electrode 3 contains nickel. The fuel electrode may contain Y (yttrium) and / or Ce (cerium) in addition to nickel. Specifically, the fuel electrode may contain yttria and / or ceria, and may contain, for example, Ni—Y ₂ O ₃ or Ni—GDC (gadolinia doped ceria) as a main component. Nickel may be an oxide (NiO), but NiO may be reduced to Ni by hydrogen gas during power generation.

The fuel electrode 3 may have a fuel electrode current collecting layer and a fuel electrode active layer. The anode current collecting layer is provided on the support substrate 2, and the anode active layer is provided on the anode current collecting layer.
As the material for the fuel electrode current collecting layer, the materials mentioned as the material for the fuel electrode 3 can be used.
The anode active layer may contain nickel and zirconia. A rare earth element may be dissolved in zirconia. Specifically, the fuel electrode active layer may contain a zirconia-based material contained in the electrolyte layer 4. Similarly to the anode current collecting layer, nickel may be an oxide (NiO) in the anode active layer, but NiO may be reduced to Ni by hydrogen gas during power generation.

  As shown in FIG. 2, the electrolyte layer 4 is provided on the fuel electrode 3 so as to cover the fuel electrode. In a region where the fuel electrode 3 is not provided, the electrolyte layer 4 may be provided on the support substrate 2. The electrolyte layer 4 is denser than the support substrate 2 and the fuel electrode 3, and together with the interconnector 7, the fuel cell 1 can be separated into air and fuel gas. The electrolyte layer 4 is also called a solid electrolyte layer.

  The electrolyte layer 4 is provided so as to continue from an interconnector 7 to an interconnector 7 adjacent to the interconnector 7 in the longitudinal direction (z-axis direction) of the support substrate 2. In other words, the electrolyte layer 4 is provided so as to continue from a certain fuel electrode 3 to the end of the fuel electrode 3 adjacent to the fuel electrode 3 in the longitudinal direction (z-axis direction) of the support substrate 2. Moreover, in the location where the interconnector 7 is provided, the electrolyte layer 4 is discontinuous in the longitudinal direction (z-axis direction) of the support substrate 2.

  The electrolyte layer 4 can contain zirconia as a main component. The electrolyte layer 4 may be a fired body of a zirconia-based material such as yttria-stabilized zirconia such as 3YSZ or 8YSZ; or ScSZ (scandia-stabilized zirconia).

  The reaction preventing layer 5 is provided on the electrolyte layer 4. In FIG. 2, the reaction preventing layer 5 is not provided at a location where the electrolyte layer 4 is not provided. That is, one reaction preventing layer 5 is provided so as to correspond to one fuel electrode 3. Therefore, a single support substrate 2 is provided with a plurality of electrolyte layers 4 along the longitudinal direction (z-axis direction) of the support substrate 2.

The reaction preventing layer 5 may contain ceria (cerium oxide) as a main component. Specifically, the material for the reaction preventing layer 5 includes ceria and a ceria-based material containing a rare earth metal oxide dissolved in ceria. Specific examples of the ceria-based material include GDC ((Ce, Gd) O ₂ : Gadolinium-doped ceria), SDC ((Ce, Sm) O ₂ : samarium-doped ceria), and the like.

  The air electrode 6 is disposed on the reaction preventing layer 5 so as not to exceed the outer edge of the reaction preventing layer 5. That is, one air electrode 6 is provided so as to correspond to one fuel electrode 3. Therefore, one support substrate 2 is provided with a plurality of air electrodes 6 along the longitudinal direction (z-axis direction) of the support substrate 2.

  The air electrode 6 may contain, for example, a lanthanum-containing perovskite complex oxide as a main component. Specific examples of the lanthanum-containing perovskite complex oxide include LSCF (lanthanum strontium cobalt ferrite), lanthanum manganite, lanthanum cobaltite, and lanthanum ferrite. The lanthanum-containing perovskite complex oxide may be doped with Sr, Ca, Cr, Co, Fe, Ni, Al, or the like.

  The interconnector 7 is stacked on the fuel electrode 3. In FIG. 2, an intermediate layer 9 to be described later is disposed between the fuel electrode 3 and the interconnector 7, but the present invention is not limited to this form, and the interconnector 7 is disposed on the fuel electrode 3. It may be provided directly. That is, “laminated” includes a case where the layers are arranged so as to be in contact with each other and a case where the layers are arranged so as not to be in contact but overlap with each other in the y axis direction.

  The interconnector 7 is disposed so as to connect the electrolyte layers 4 in the longitudinal direction (z-axis direction) of the support substrate 2. Thereby, the power generation units 10 adjacent in the longitudinal direction (z-axis direction) of the support substrate 2 are electrically connected.

  The interconnector 7 is a dense layer as compared with the support substrate 2 and the fuel electrode 3. The interconnector 7 contains a chromite material.

The chromite-based material is a complex oxide that may be referred to as a chromite-based perovskite oxide. Specifically, the chromite material is represented by the following general formula (1):
_{Ln 1-x A x Cr 1} -yz B y O 3 (1)
(In the formula (1), Ln is at least one element selected from the group consisting of Y and lanthanoids, A contains at least one element selected from the group consisting of Ca, Sr and Ba, B contains at least one element selected from the group consisting of Ti, V, Mn, Fe, Co, Cu, Ni, Zn, Mg, and Al, and 0.025 ≦ x ≦ 0.3, 0 ≦ (y ≦ 0.22, 0 ≦ z ≦ 0.15)
It may be represented by
The interconnector 7 preferably contains a chromite material as a main component.

Lanthanoids include La, Ce, Eu, Sm, Yb, Gd and the like.
At least one condition of 0.05 ≦ x ≦ 0.2, 0.02 ≦ y ≦ 0.22, and 0 ≦ z ≦ 0.05 may be satisfied.

  The A site can contain one or more alkaline earth metal elements. Specific examples of the alkaline earth metal element include Mg, Ca, Sr, and Ba. By containing the alkaline earth metal element, the interconnector 7 can be fired at a relatively low temperature.

  The current collecting layer 8 is disposed so as to electrically connect the interconnector 7 and the power generation unit 10. Specifically, the current collecting layer 8 is provided so as to continue from the air electrode 6 to the interconnector 7 included in the power generation unit 10 adjacent to the power generation unit 10 including the air electrode 6. The current collection layer 8 should just have electroconductivity, for example, may be comprised with the material similar to the interconnector 7. FIG.

  An intermediate layer 9 is disposed between the fuel electrode 3 and the interconnector 7.

  The intermediate layer 9 contains a chromite material and Ni. The chromite material contained in the intermediate layer 9 need not be the same as the chromite material contained in the interconnector 7. For example, when the chromite material contained in the interconnector 7 is represented by the formula (1) and the element Ln in the formula (1) is La, the element Ln in the intermediate layer 9 is an element other than La (for example, Y) It may be. Further, the element A in the interconnector 7 may be Ca, and the element A in the intermediate layer 9 may be Sr.

  The element Ln in the intermediate layer 9 and the element Ln in the interconnector 7 may be the same. The same applies to the elements contained in the A site and the B site. Further, the intermediate layer 9 may further contain other elements contained in the interconnector 7. Further, the chromite material contained in the intermediate layer 9 may be the same as the chromite material contained in the interconnector 7.

  As another expression, the intermediate layer 9 may contain at least one element among elements constituting the fuel electrode 3 and at least one element among elements constituting the interconnector 7. For example, the intermediate layer 9 can contain Ln, Cr, and Ni. Further, the intermediate layer 9 may further contain other elements contained in the interconnector 7.

  In the intermediate layer 9, the generation of cracks when firing and reduction are suppressed.

  When the intermediate layer 9 has the above-described composition, it is difficult to form an aggregated layer between the intermediate layer 9 and the interconnector 7. Therefore, the occurrence of cracks and peeling in the intermediate layer is suppressed.

  Further, the intermediate layer 9 of the present embodiment contains Ni and a chromite material, so that the fuel electrode 3 containing Ni and the chromite material (the chromite material contained in the intermediate layer may be different). It is possible to increase the bonding strength between the interconnector 7 and the fuel electrode 3.

By the way, conventionally, an intermediate layer formed of titanate has been proposed. For example, JP-T-2010-525226 discloses n-doped titanate as an intermediate layer between an interconnector and an electrode. Japanese Patent No. 4196223 discloses a mixture of niobium titanate and calcium titanate as an intermediate layer. However, with these titanate materials, it is difficult to achieve sufficient electrical conductivity. For example, according to Japanese Patent No. 3723189, the high-temperature conductivity of the calcium titanate material is on the order of 10 ^-1 S / cm.
In contrast, the high temperature conductivity of Ni is on the order of 10 ⁵ S / cm. That is, the intermediate layer 9 can realize good electrical conductivity by containing Ni.

Further, when the intermediate layer is NiO—ZrO ₂ , the alkaline earth metal (Ca, Sr, Ba, etc.) of the interconnector easily moves to the intermediate layer. When the alkaline earth metal moves and the concentration of the alkaline earth metal in the interconnector decreases, there arises a problem that firing of the interconnector becomes incomplete. On the other hand, according to the configuration of the present embodiment, the interconnector 7 is sufficiently fired.

In the vertical stripe fuel cell, the area of the power generation unit and the area of the interconnector are generally the same. On the other hand, in the horizontal stripe fuel cell, the area of the interconnector is generally smaller than the area of the power generation unit. Therefore, in the horizontal stripe fuel cell, a current density higher than the current density of the power generation unit is generated in the interconnector. Therefore, a decrease in output due to an increase in resistance, which has hardly been a problem in the conventional vertical stripe fuel cell, is noticeable. Therefore, in the horizontal stripe fuel cell, it is an extremely important issue to suppress an increase in electrical resistance generated in the interconnector and its surroundings.
According to the configuration of the present embodiment, as described above, an aggregated layer is unlikely to be formed between the intermediate layer 9 and the interconnector 7. As a result, an increase in electrical resistance between the interconnector 7 and the fuel electrode 3 is suppressed. Therefore, the technique of the present embodiment is particularly useful in a horizontal stripe fuel cell.

  The volume ratio of the chromite-based material and Ni contained in the intermediate layer 9 can be set to 70:30 to 30:70, for example.

  The thickness of the intermediate layer 9 is not limited to a specific numerical value, but can be set to, for example, 5 to 100 μm.

  The power generation unit 10 is a part including a fuel electrode 3 and an air electrode 6 corresponding to the fuel electrode 3. Specifically, the power generation unit 10 includes a fuel electrode 3, an electrolyte layer 4, a reaction prevention layer 5, and an air electrode 6 that are stacked in the thickness direction (y-axis direction) of the support substrate 2.

  As shown in FIG. 2, the air electrode 6 included in the power generation unit 10 is electrically connected to the fuel electrode 3 of the adjacent power generation unit 10 by the current collecting layer 8 and the interconnector 7. In other words, not only the interconnector 7 but also the current collecting layer 8 contributes to the connection between the power generation units 10, and such a configuration is also included in the configuration in which the interconnector “electrically connects the power generation units”. Is done.

Specifically, the dimensions of each part of the fuel cell 1 can be set as follows.
Width D1 of support substrate 2: 1 to 10 cm
Support substrate 2 thickness D2: 1 to 10 mm
Support substrate 2 length D3: 5 to 50 cm
Distance D4 from outer surface of support substrate 2 (interface between support substrate 2 and fuel electrode) to flow path 21: 0.1 to 4 mm
The thickness of the fuel electrode 3: 50 to 500 μm
(When the anode 3 has an anode current collecting layer and an anode active layer:
The thickness of the anode current collecting layer: 50 to 500 μm
(The thickness of the anode active layer: 5 to 30 μm)
Electrolyte layer 4 thickness: 3 to 50 μm
Reaction prevention layer 5 thickness: 3 to 50 μm
Thickness of the air electrode 6: 10 to 100 μm
The thickness of the interconnector 7: 10 to 100 μm
Current collecting layer 8 thickness: 50 to 500 μm
Needless to say, the present invention is not limited to these values.

<2. Second Embodiment>
Next, the configuration of the solid oxide fuel cell 1 according to the second embodiment will be described. The difference from the first embodiment is that the thickness ratio of the intermediate layer 9 to the interconnector 7 is defined. Since the other configuration is the same as that of the solid oxide fuel cell 1 according to the first embodiment, differences from the first embodiment will be mainly described below.
(Configuration of solid oxide fuel cell 1)
In the present embodiment, the interconnector 7 contains a lanthanum chromite material. The lanthanum chromite material is a general term for materials represented by the following general formula (2).
_{La 1-x A x Cr 1} -yz B y O 3 (2)
However, in Formula (2), A is at least 1 type of alkaline-earth metal element selected from the group which consists of Ca, Sr, and Ba, B is Ti, V, Mn, Fe, Co, Cu, Ni , Zn, Mg, and Al, and at least one element selected from the group consisting of 0.025 ≦ x ≦ 0.3, 0 ≦ y ≦ 0.22, and 0 ≦ z ≦ 0.15.
As such a lanthanum chromite material, LCC (calcium dope lanthanum chromite: (La, Ca) CrO ₃ ) or LSC (strontium dope lanthanum chromite: (La, Sr) CrO ₃ ) is preferably used. The thickness of the interconnector 7 can be set to 10 μm or more and 60 μm or less.
In the present embodiment, the intermediate layer 9 contains NiO and a lanthanum chromite material. The lanthanum chromite material contained in the intermediate layer 9 may be the same as the lanthanum chromite material contained in the interconnector 7. The thickness of the intermediate layer 9 is set to 10 μm or less.
Here, in the thickness direction of the solid oxide fuel cell 1, the ratio (P / Q) of the thickness (P) of the interconnector 7 to the thickness (Q) of the intermediate layer 9 is preferably 4.4 or more. More preferably, it is 20 or less. In other words, the ratio between the thickness (P) of the interconnector 7 and the thickness (Q) of the intermediate layer 9 is preferably between 40: 9 and 20: 1.
(Function and effect)
In the solid oxide fuel cell 1 according to this embodiment, the thickness (Q) of the intermediate layer 9 is 10 μm or less. Further, the ratio (P / Q) of the thickness (P) of the interconnector 7 to the thickness (Q) of the intermediate layer 9 is 4.4 or more.
Thus, since the interconnector 7 is formed sufficiently thicker than the intermediate layer 9, alkaline earth metal elements (Ca, Sr, Ba, etc.) move from the interconnector 7 to the intermediate layer 9 during firing. Can be suppressed. Therefore, since the shortage of sintering aid in the interconnector 7 can be suppressed, the denseness of the interconnector 7 can be improved.
<3. Other Embodiments>
In the first embodiment, the horizontal stripe type is used as the fuel cell. That is, in the first embodiment, in the fuel cell 1, two or more power generation units 10 are provided on one support substrate 2, and the interconnector 7 is provided on one support substrate 2. It arrange | positions so that between the electric power generation parts 10 may be electrically connected.

  However, the present invention may be applied to a vertical stripe type. That is, a plurality of power generation units including a fuel electrode layer, an electrolyte layer, and an air electrode layer that are stacked may be stacked in the thickness direction of the layers. In this case, the interconnector is disposed so as to electrically connect the power generation units adjacent in the thickness direction. In this case, a layer similar to the current collector 8 may be provided in addition to the interconnector as necessary.

  Both the vertical stripe type and the horizontal stripe type are included in the form in which the interconnector “electrically connects the power generation units”.

[Production of Sample Pieces According to Examples 1-3 and Comparative Examples 1-3]
Sample pieces according to Examples 1 to 3 and Comparative Examples 1 to 3 were produced as follows.
First, NiO powder and Y ₂ O ₃ powder were mixed so that Ni: Y ₂ O ₃ = 40: 60% by volume in terms of Ni after reduction. Further, cellulose powder having a weight of 20% of the total weight of NiO powder and Y ₂ O ₃ powder was added as a pore former and mixed. The mixture was granulated by SD method (spray drying method). The obtained granules were formed into pellets by compacting performed under a pressure of 100 MPa using a CIP method (Cold Isostatic Press) to obtain a NiO-Y ₂ O ₃ compact.

On the NiO—Y ₂ O ₃ molded body, an intermediate layer was formed by screen printing, and then an interconnector was formed by screen printing.
The paste used for printing the intermediate layer was obtained by adding and mixing raw material powder, ethyl cellulose as a binder, and terpioneer as a solvent. The raw material powder of Example 1 was a mixture of NiO: (La, Ca) CrO ₃ = 1: 1 (volume ratio). (La, Ca) CrO ₃ is hereinafter referred to as “LCC” (calcium dopeplank chromite). Moreover, the raw material powder of the intermediate | middle layer of Comparative Examples 1-3 was a mixture of the ratio (volume ratio) of NiO: GDC = 1: 1. Note that GDC is represented by (Ce _0.9 Gd _0.1 ) O ₂ .
The paste used for interconnector printing was prepared in the same manner as the intermediate layer paste except that LCC was used in place of the intermediate layer Ni-LCC and Ni-GDC.
The LCC used for forming the interconnector and the LCC used for forming the intermediate layer of Example 1 have the same composition.

Next, the NiO—Y ₂ O ₃ molded body, the intermediate layer, and the interconnector were co-fired at 1500 ° C. A sample piece was cut out from the obtained fired body.

The sample piece thus obtained was a disk having a total thickness (total thickness of NiO—Y ₂ O ₃ plate, intermediate layer and interconnector) of 1.0 mm and a diameter of 12 mm. The intermediate layer had a thickness of 5 μm, and the interconnector had a thickness of 30 μm.

[Reduction treatment]
The sample piece was set in the voltage evaluation apparatus, and the voltage drop after NiO reduction was measured. The voltage evaluation apparatus includes a capsule divided into an upper part and a lower part. Pt pedestals are respectively arranged in the upper and lower portions of the capsule, and potential lines and current lines are connected to each Pt pedestal. The sample piece is arranged so that the interconnector is in contact with the Pt pedestal in the upper part of the capsule and the NiO—Y ₂ O ₃ plate is in contact with the Pt pedestal in the lower part of the capsule. The capsule and the sample piece were sealed with molten glass to prevent gas mixing between the top and bottom of the capsule. 35% H2 / Ar gas was allowed to flow in the lower part of the capsule, and air was allowed to flow in the upper part of the capsule.
After NiO was sufficiently reduced, the potential was measured by passing a constant current of 1 A through the Pt pedestal at 750 ° C. The resistance value was calculated from the obtained potential according to Ohm's law.
Moreover, the intermediate | middle layer after reduction | restoration was observed with the electron microscope, and the presence or absence of the crack was confirmed.

※ ＬＣＣは（Ｌａ，Ｃａ）ＣｒＯ₃を表し、ＬＳＣは（Ｌａ，Ｓｒ）ＣｒＯ₃を表し、ＹＣＣは（Ｙ，Ｃａ）ＣｒＯ₃を表す。

* LCC represents (La, Ca) CrO ₃ , LSC represents (La, Sr) CrO ₃ , and YCC represents (Y, Ca) CrO ₃ .

表２に示されるように、インターコネクタの厚み（Ｐ）の中間層９の厚み（Ｑ）に対する比（Ｐ/Ｑ）は、４．４以上であることが好ましく、２０以下であることがより好ましいことが分かった。これは、インターコネクタを中間層に比べて十分に厚く形成することによって、焼成時にインターコネクタから中間層へＣａの移動が抑制され、インターコネクタにおける焼結助剤の不足を抑制できたためである。 [result]
As shown in Table 1, in Example 1, no crack was found in the reduced intermediate layer. Moreover, the sample of Example 1 had a low electrical resistance value. On the other hand, in Comparative Examples 1 to 3, the occurrence of cracks was observed, and the obtained electrical resistance value was relatively high.
[Production of Sample Pieces According to Examples 4 to 16 and Comparative Examples 4 to 6]
Sample pieces according to Examples 4 to 16 and Comparative Examples 4 to 6 were produced as follows.
First, Ni: Y ₂ O ₃ = 40: 60% by volume in terms of Ni after reduction was weighed, and NiO powder and Y ₂ O ₃ powder were mixed in a pot mill. Next, the mixed powder was molded at a molding pressure of 0.4 t / cm ² by uniaxial pressing and then molded at a molding pressure of 3 t / cm ² by the CIP method to obtain a NiO—Y ₂ O ₃ molded body having a diameter of 40 mm. .
Next, it was weighed so that Ni: LCC = 50: 50 vol% in terms of Ni after reduction, and NiO powder and LCC powder were mixed in a pot mill. Next, an intermediate layer paste was obtained by mixing the mixed powder with polyvinyl bratil as a binder and terpineol as a solvent.
Next, the intermediate layer paste was printed on the NiO—Y ₂ O ₃ compact. At this time, the thickness of the intermediate layer after firing was changed by increasing or decreasing the number of times of printing for each sample.
Next, the paste for interconnectors was obtained by mixing polyvinyl bratil and terpineol with the LCC powder.
Next, the interconnector paste was printed on the dried intermediate layer paste. At this time, the thickness of the interconnector after firing was changed by increasing or decreasing the number of times of printing for each sample.
Thereafter, a laminate of the NiO—Y ₂ O ₃ molded body, the intermediate layer paste, and the interconnector paste was co-fired at 1500 ° C. for 2 hours. In addition, the thickness of the interconnector and intermediate | middle layer after baking is put together in Table 2, and is shown.
[Measurement of porosity]
As described below, the cross-sectional observation of the sample pieces according to Examples 4 to 16 and Comparative Examples 4 to 6 was performed, and the porosity was measured.
First, the pores inside the interconnector were impregnated with the resin by evacuating each sample after the reduction treatment while dropping epoxy resin. After the resin was cured overnight, the cut surface of the interconnector was obtained by cutting each sample along the thickness direction with a microcutter.
Next, the cut surface was conditioned with a # 600 water-resistant wafer, and then the cross-section was smoothed with an ion milling device (JEOL Cross Section Polisher).
Next, the cross section of each sample was observed with a high-resolution FE-SEM capable of observing at low acceleration without vapor deposition. The pores were identified based on the contrast difference in the SEM photograph, the volume ratio was estimated from the area ratio of the pores in the cross section, and the relative density of the interconnector was calculated from the estimation result. In addition, about the method of estimating a three-dimensional structure from a two-dimensional organization, “Mizutani Satoshi, Ozaki Yoshiharu, Kimura Toshio, Yamaguchi Satoshi,“ Ceramic Processing ”, Gihodo Publishing Co., Ltd., published on March 25, 1985 From page 190 to page 201 ".
The relative density calculation results are summarized in Table 2.
[Density evaluation test]
The test which evaluates the compactness of the sample piece which concerns on Examples 4-16 and Comparative Examples 4-6 as follows was done.
First, it was reduced over a period of 2 hours at 800 ° C. while passing H ₂ gas (30 ° C. humidified) to each specimen.
Next, as shown in FIG. 3, each sample was fixed to the jig with an epoxy adhesive, and ethanol was stored on the interconnector side.
Next, He gas was supplied to the current collecting layer side at a gauge pressure of 0.2 atm.
At this time, if foaming was not confirmed in ethanol, it was evaluated as being sufficiently dense, and if foaming was confirmed in ethanol, it was evaluated as insufficient. In general, as described in “Mizutani Atsushi, Ozaki Yoshiharu, Kimura Toshio, Yamaguchi Atsushi,“ Ceramic Processing ”, Gihodo Publishing Co., Ltd., published on March 25, 1985, p. 137” When the relative density is 95% or more, it is recognized as a dense body that does not transmit gas, and the evaluation results are summarized in Table 2.

As shown in Table 2, the ratio (P / Q) of the thickness (P) of the interconnector to the thickness (Q) of the intermediate layer 9 is preferably 4.4 or more, and more preferably 20 or less. It turned out to be preferable. This is because by forming the interconnector sufficiently thicker than the intermediate layer, the movement of Ca from the interconnector to the intermediate layer during firing was suppressed, and the shortage of sintering aid in the interconnector could be suppressed.

1 Horizontally striped solid oxide fuel cell (solid oxide fuel cell)
2 Support Substrate 3 Fuel Electrode 4 Electrolyte Layer 5 Reaction Prevention Layer 6 Air Electrode 7 Interconnector 8 Current Collection Layer 9 Intermediate Layer 10 Power Generation Unit 21 Channel

Claims (5)

Two or more power generation units each having an air electrode, a nickel-containing fuel electrode, and an electrolyte layer disposed between the air electrode and the fuel electrode;
An interconnector containing a chromite-based material and arranged to electrically connect two or more of the power generation units;
An intermediate layer disposed between the interconnector and the fuel electrode, containing a chromite-based material and nickel;
A solid oxide fuel cell. The chromite material is
The following general formula (1):
_{Ln 1-x A x Cr 1} -yz B y O 3 (1)
(In the formula (1), Ln is at least one element selected from the group consisting of Y and lanthanoids, A contains at least one element selected from the group consisting of Ca, Sr and Ba, B contains at least one element selected from the group consisting of Ti, V, Mn, Fe, Co, Cu, Ni, Zn, Mg, and Al, and 0.025 ≦ x ≦ 0.3, 0 ≦ (y ≦ 0.22, 0 ≦ z ≦ 0.15)
The solid oxide fuel cell according to claim 1, represented by: The interconnector is made of a lanthanum chromite material,
The intermediate layer is composed of NiO and lanthanum chromite material,
The ratio of the thickness of the interconnector to the thickness of the intermediate layer is 4.4 or more.
The solid oxide fuel cell according to claim 1 or 2. 4. The solid oxide fuel cell according to claim 1, wherein the fuel electrode further contains Y and / or Ce. 5. Further comprising a substrate,
Two or more power generation units are provided on one of the substrates,
5. The solid oxide fuel cell according to claim 1, wherein the interconnector is disposed so as to electrically connect the power generation units provided on one substrate. 6.

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