JP2006236820A - Solid oxide fuel cell and manufacturing method of solid oxide fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solid oxide fuel cell capable of preventing overvoltage of an air electrode from augmenting and a manufacturing method of a solid oxide fuel cell. <P>SOLUTION: Transition metal oxide contained in an intermediate layer 5 dissolves only slightly in a solid electrolyte in a solid state at an operating temperature of the SOFC in an oxidation atmosphere, but does not contain rare earth elements with large ionic radii such as La and Sr. Therefore, even if a high temperature heat treatment is applied to have it stably exist at an interface with zirconia, interdiffusion with the electrolyte 2 hardly occurs, and a non-conductive phase such as of pyrochroite is not generated. Thereby, it becomes possible to prevent increase of overvoltage of the air electrode 3 by providing the above intermediate layer 5. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a solid oxide fuel cell (SOFC).

  In recent years, interest in SOFCs using oxygen ion conductors is increasing. This SOFC has excellent characteristics such as high energy conversion efficiency because it is not restricted by Carnot efficiency and good environmental conservation. For this reason, it is especially expected from each field from the viewpoint of effective use of energy.

  In the conventional SOFC, since the operating temperature is as high as 900 ° C. to 1000 ° C., all members must be made of ceramic, and it is difficult to reduce the manufacturing cost of the cell stack. If the operating temperature of the SOFC can be reduced to 800 ° C. or less, preferably about 700 ° C., it becomes possible to use a heat-resistant alloy material for the interconnector and the like, so that the manufacturing cost can be reduced. However, when the operating temperature is lowered, the electrochemical resistance in the air electrode is rapidly increased, so that an overvoltage is increased, resulting in a new problem that the output voltage is lowered. In order to solve the problem of an increase in the overvoltage of the air electrode, miniaturization of the air electrode and development of a new air electrode material have been performed. Among them, the method of reducing the particle size of the material constituting the air electrode is the most effective method because it can always reduce the overvoltage.

The applicant has not yet found prior art documents related to the present invention by the time of filing other than the prior art documents specified by the prior art document information described in this specification.
WA Fischer and A. Hoffmann, Arch. Eisenhuettenwes., Vol.28 [11], P.739-743, 1957

By the way, the air electrode is generally formed by applying the material constituting the air electrode on the electrolyte layer, baking it, and baking it on the electrolyte layer. If baking at this time is performed at an excessively high temperature, Since these particles coalesce to cause grain growth, the overvoltage of the air electrode is increased. In particular, when a zirconia-based material is used as the electrolyte and a La-based material is used as the air electrode, a rare earth element having a large ionic radius such as La is likely to diffuse into the electrolyte, so that SrZrO ₃ or a pyrochlore phase (La ₂ Since an inert substance having extremely low electronic conductivity and ionic conductivity such as Zr ₂ O ₇ ) is formed at the interface between zirconia and the air electrode, the overvoltage of the air electrode is increased. On the other hand, when the baking temperature is too low, the adhesion between the constituent material of the air electrode and zirconia is reduced, and the air electrode is easily peeled off from the electrolyte. As a result, the thermal cycle characteristics are deteriorated and the reliability of the SOFC is lowered. Thus, conventionally, it has been difficult to reduce the overvoltage by reducing the particle size of the material constituting the air electrode.

  Therefore, the present invention has been made to solve the above-described problems, and a solid oxide fuel cell and a method for manufacturing the solid oxide fuel cell that can prevent an overvoltage of the air electrode from increasing. The purpose is to provide.

  In order to solve the above-described problems, a solid oxide fuel cell according to the present invention is a solid oxide in which an air electrode and a fuel electrode are provided on both surfaces of an electrolyte layer, and an intermediate layer is provided between the electrolyte layer and the air electrode. In the oxide fuel cell, the electrolyte layer is composed of rare earth-added zirconia, the air electrode is composed of a first metal composed of La or La and Sr, and at least one of Fe, Co, Mn, and Ni. It is composed of a metal oxide having a perovskite structure composed of a second metal composed of an element, and the intermediate layer is composed of an oxide containing at least one element of Fe, Co, Mn, and Ni. And

  In the solid oxide fuel cell, the thickness of the intermediate layer may be 0.01 μm or more and 1 μm or less.

  In the solid oxide fuel cell, the intermediate layer is composed of a mixed oxide containing rare earth-added zirconia and any one or more elements of Fe, Co, Mn, and Ni. It may be. Here, the rare earth added zirconia may be mixed at a ratio of 1 to 80 wt%. Further, the thickness of the intermediate layer may be 0.02 μm or more and 2 μm or less.

  The method for producing a solid oxide fuel cell according to the present invention is a solid oxide type in which an air electrode and a fuel electrode are provided on both surfaces of an electrolyte layer, and an intermediate layer is formed between the electrolyte layer and the air electrode. A method for manufacturing a fuel cell, in which a solution containing one or more elements of Fe, Co, Mn, and Ni is applied on an electrolyte layer made of rare earth-added zirconia and baked to form an intermediate layer A perovskite comprising: an intermediate layer forming step; a first metal composed of La or La and Sr; and a second metal composed of at least one element of Fe, Co, Mn, and Ni on the intermediate layer. And an air electrode forming step in which a slurry containing a metal oxide having a structure is applied and fired to form an air electrode.

  Further, another method of manufacturing a solid oxide fuel cell according to the present invention includes a solid oxide in which an air electrode and a fuel electrode are provided on both surfaces of an electrolyte layer, and an intermediate layer is formed between the electrolyte layer and the air electrode. A method for manufacturing a physical fuel cell, wherein a solution containing at least one element of Fe, Co, Mn, and Ni is applied onto an electrolyte layer made of rare earth-added zirconia and dried to form a thin film A perovskite structure comprising a thin film forming step, a first metal composed of La or La and Sr, and a second metal composed of at least one element of Fe, Co, Mn, and Ni on the thin film. And a forming step of applying a slurry containing a metal oxide and firing to form an air electrode and an intermediate layer.

  Further, another method of manufacturing a solid oxide fuel cell according to the present invention includes a solid oxide in which an air electrode and a fuel electrode are provided on both surfaces of an electrolyte layer, and an intermediate layer is formed between the electrolyte layer and the air electrode. A method for manufacturing a physical fuel cell, wherein an intermediate layer made of an oxide containing at least one element of Fe, Co, Mn, and Ni is formed by an vacuum film forming method, and an electrolyte layer made of rare earth-added zirconia An intermediate layer forming step formed thereon, a first metal composed of La or La and Sr, and a second metal composed of at least one element of Fe, Co, Mn, and Ni on the intermediate layer; And an air electrode forming step in which a slurry containing a metal oxide having a perovskite structure is applied and fired to form an air electrode.

  According to the present invention, the intermediate layer made of an oxide of at least one element of Fe, Co, Mn, and Ni, the electrolyte made of rare earth-added zirconia, and the first metal made of La or La and Sr And the perovskite structure metal oxide composed of the second metal composed of at least one of Fe, Co, Mn, and Ni, the overvoltage of the air electrode is increased. Can be prevented.

[First Embodiment]
Hereinafter, a first embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a cross-sectional view schematically showing the configuration of a single cell of a solid oxide fuel cell according to the present embodiment. In FIG. 1, a single cell 1 is formed on an electrolyte layer 2, an air electrode 3 formed on one surface of the electrolyte layer 2 via an intermediate layer 5, and another surface of the electrolyte layer 2. A fuel electrode 4 is provided.

  The electrolyte layer 2 is composed of a rare earth-added zirconia oxide.

In the air electrode 3, La (Sr) MnO ₃ , La (occupying the A site with La or La and Sr and the B site with at least one of transition metal elements such as Fe, Co, Mn, Ni, etc. It is composed of a porous material having a perovskite structure (ABO ₃ ) such as Sr) Fe _0.8 Co _0.2 O ₃ , LaNi _0.6 Fe _0.4 O ₃ .

  The fuel electrode 4 is made of a material used as a fuel electrode of a solid oxide fuel cell such as NiO-YSZ.

  The intermediate layer 5 is made of a metal oxide composed of at least one of transition metal elements such as Fe, Co, Mn, and Ni, or a mixture of the transition metal oxide and rare earth-added zirconia oxide. Composed.

  Such a single cell 1 is formed as follows. First, the electrolyte layer 2 having a thickness of about 10 to 10 μm is formed by a known method such as a doctor blade method.

  Next, after forming the fuel electrode 4 on one surface of the electrolyte layer 2, an organic metal salt solution or an inorganic metal solution is applied to the other surface of the electrolyte layer 2, and this solution is dried and fired or dried by heat treatment. Thereby, the intermediate layer 5 made of a transition metal oxide or a thin film made of a mixture of a rare earth-added zirconia-based oxide and a transition metal oxide is formed. The intermediate layer 5 may be formed by a known vacuum film forming method such as an RF sputtering method.

  Next, the material of the air electrode 3 is applied in a slurry form on the intermediate layer 5 or the thin film by a known method such as screen printing, and is fired at a temperature higher than the operating temperature of the SOFC, whereby the air electrode 3 or the air electrode 3 and the intermediate layer 5 are formed. Thereby, the single cell 1 as shown in FIG. 1 is formed.

  In the single cell 1 formed in this way, the transition metal oxide composed of metal elements such as Fe, Co, Mn, and Ni contained in the intermediate layer 5 is converted into a solid electrolyte having a meteorite-type crystal lattice such as zirconia and ceria. The solid solution dissolves very slightly at the operating temperature of SOFC in an oxidizing atmosphere (see, for example, Non-Patent Document 1). However, since the transition metal oxide does not contain a rare earth element having a large ionic radius such as La or Sr, even if heat treatment is performed at a high temperature in order to stably exist at the interface with zirconia, Interdiffusion hardly occurs between them, and non-conductive phases such as pyrochlore are not generated. For this reason, by providing the intermediate layer 5 described above, it is possible to prevent an increase in overvoltage of the air electrode 3.

Further, as described above, the transition metal oxide contained in the intermediate layer 5 is slightly dissolved in the electrolyte layer 2, whereby the adhesion between the transition metal oxide of the intermediate layer 5 and the zirconia of the electrolyte layer 2 is increased. . The transition metal oxide is a perovskite oxide having a composition represented by ABO ₃ such as La (Sr) MnO ₃ , La (Sr) Fe _0.8 Co _0.2 O ₃ , LaNi _0.6 Fe _0.4 O ₃ constituting the air electrode 3. Since it has the same metal element as the B site, it easily interdiffuses with the air electrode 3. Since the intermediate layer 3 is formed to be sufficiently thin on the order of microns, when the air electrode 3 is baked on the intermediate layer 5, the interdiffusion region between the air electrode 3 and the intermediate layer 5 is an interface between the electrolyte layer 2 and zirconia. To reach. For this reason, when the air electrode 3 is baked on the intermediate layer 5, it is sufficient between the electrolyte layer 2 and the air electrode 3 through the intermediate layer 5 even if the baking temperature of the air electrode 3 is relatively low. Since the adhesion is obtained, the air electrode 3 can be prevented from peeling off from the electrolyte layer 2. Further, since the composition of the intermediate layer 5 is also close to the composition of the air electrode 3, the electrochemical activity between the electrolyte layer 2 and the air electrode 3 is not impaired. Thereby, increase of the overvoltage of the air electrode 3 can also be prevented.

  Therefore, when the intermediate layer 5 is made of a transition metal oxide, the thickness of the intermediate layer 5 is 0.01 μm or more so that the intermediate layer 5 does not melt and disappear even through a high-temperature process in manufacturing the single cell 1. 1 μm or less, preferably 0.05 μm or more and 0.5 μm or less, more preferably 0.08 μm or more so that the interdiffusion region between the air electrode 3 and the intermediate layer 5 reaches the interface with the zirconia of the electrolyte layer 2. It is formed to 0.2 μm or less.

  On the other hand, when composed of a mixture of rare earth-added zirconia-based oxide and transition metal oxide, the thickness of the intermediate layer 5 is such that the intermediate layer 5 is melted even through a high-temperature process when the single cell 1 is manufactured. 0.02 μm or more which does not disappear, and 2 μm or less, preferably 0.04 μm or more and 1 μm or less so that the interdiffusion region between the air electrode 3 and the intermediate layer 5 reaches the interface with the zirconia of the electrolyte layer 2. More desirably, it is formed to be 0.05 μm or more and 0.5 μm or less. At this time, the ratio of the rare earth-added zirconia oxide mixed in the intermediate layer 5 is set to 1 to 80 wt%, desirably 10 to 70 wt%, and more desirably 40 to 60 wt%.

[Second Embodiment]
Next, a second embodiment according to the present invention will be described. FIG. 2 is a schematic diagram showing the configuration of a single cell of the solid oxide fuel cell according to the present embodiment, and FIG. 3 is a cross-sectional view of the main part schematically showing the configuration of the fuel cell incorporating the single cell of FIG. FIG. 4 and FIG. 4 are schematic views showing the configuration of a single cell for adhesion test. The present embodiment more specifically represents the first embodiment described above.

  In the present embodiment, a single cell as shown in FIG. 2 is formed under a predetermined condition to be described later, and this single cell is incorporated into a fuel cell as shown in FIG. 3 to perform a power generation test. Moreover, in order to perform the adhesion test of an air electrode, the single cell as shown in FIG. 4 was formed. First, a single cell and a fuel cell incorporating the single cell will be described.

  As shown in FIG. 2, the unit cell 10 includes an electrolyte layer 11 having a plate-like shape having a substantially rectangular shape in plan view, and a fuel electrode 12 having a substantially circular shape in plan view formed on one surface of the electrolyte layer 11. A substantially circular air electrode 13 in plan view formed on the other surface of the electrolyte layer 11, an intermediate layer 14 formed between the electrolyte layer 11 and the air electrode 13, and a surface on the side where the air electrode 13 is formed. And a reference electrode 15 formed at the edge of the electrolyte layer 11. Platinum mesh current collectors 16 and 17 are formed on the surfaces of the fuel electrode 12 and the air electrode 13 in order to improve the current collection efficiency.

As shown in FIG. 3, the fuel cell 20 includes the unit cell 10 described above, a cell cover 30 that holds the portion of the electrolyte layer 11 of the unit cell 10 through the seal 31 and holds the unit cell 10 in an airtight manner, an air supply unit 40 which is disposed on the air electrode 13 side to exhaust the excess air or O ₂ supply air or O ₂ of the single cell 10 is disposed in the fuel electrode 12 side of the unit cell 10 H _2, H _The generated power connected to the fuel supply unit 50 for supplying fuel gas such as ₂ + H ₂ O, CH ₄ + H ₂ O and the like and exhausting the exhaust gas, and the platinum mesh current collectors 16, 17 of the bipolar electrode of the single cell 10 is generated. A terminal 60 made of platinum to be taken out and a reference terminal 70 to take out reference power from the reference electrode 15 of the single cell 10 are provided.

Next, a method for manufacturing the single cell 10 will be described. First, a NiO—YSZ slurry is formed on one surface of an electrolyte layer 11 made of Y ₂ O ₃ -added zirconia (YSZ or 0.9ZrO ₂ -0.1Y ₂ O ₃ ) having a thickness of 0.2 mm fired by a doctor blade method. Was applied by screen printing, and a platinum mesh current collector 16 was placed thereon and baked at 1400 ° C. for 8 hours to form a fuel electrode 12 having a thickness of 60 μm. The NiO—YSZ slurry is composed of 40 wt% of Y ₂ O ₃ added zirconia having an average particle diameter of about 0.6 μm and 60 wt% of NiO powder having an average particle diameter of about 0.2 μm. .

  Next, an alkoxide solution containing Co diluted with toluene is applied to the other surface of the electrolyte layer 11 by a spin coating method, dried at 400 ° C., and then baked at 1000 ° C. for 4 hours. An intermediate layer 14 made of 0.1 μm cobalt oxide was formed. The intermediate layer 14 having a thickness of 0.1 μm or more was formed by drying at 400 ° C. and repeated spin coating of the alkoxide solution.

Next, a slurry of La _0.8 Sr _0.2 MnO ₃ (LSM) having a particle size of about 0.8 μm composed of La and Sr at the A site and Mn at the B site is formed on the intermediate layer 14 having a predetermined thickness. The platinum mesh current collector 17 was placed thereon and baked at 1000 ° C. for 2 hours to form an air electrode 13 having a thickness of 60 μm. The fuel electrode 12 and the air electrode 13 were both formed to have a diameter of 6 mm.

  Cells having different thicknesses of the intermediate layer 14 formed by such a method are designated as cells # 101 to 105, respectively.

  Further, in the same manner as described above, instead of the Co-containing alkoxide solution, an intermediate layer using a Fe-containing alkoxide solution, a Mn-containing alkoxide solution, a Ni-containing alkoxide solution, or a Fe-containing alkoxide solution and a Co-containing alkoxide solution is used. The cells in which 14 is formed are referred to as cells # 111 to 143, respectively.

Further, an intermediate layer 14 is not formed by the same method as described above, but an LSM (La _0.78 Sr _0.2 MnO ₃ ) slurry having a particle size of 0.8 μm is applied on the electrolyte layer 11, and a platinum mesh is applied thereon. A current collector 17 was placed and baked at 1000 ° C. for 4 hours to form a 60 μm thick air electrode 13 as a reference cell. This cell is designated as # 100.

The cells # 100 to 143 were incorporated into a fuel cell 20 as shown in FIG. 3 as a single cell 10 and a power generation test was performed at 800 ° C. In this power generation test, the interfacial resistance, which is an index of electrode performance, was measured by the AC impedance method. Further, in the cells # 100 to 143, as shown in FIG. 4, a cell in which the fuel electrode 12 and the reference electrode 15 are not provided and the electrolyte layer 11 is formed in a rectangular shape of 1 cm square is also produced, and an adhesion test is performed. Went. In this adhesion test, a tape was attached to the air electrode 13 after firing, and the residual ratio after peeling the tape was measured. These test results are shown in Table 1. In the power generation test, O ₂ was supplied from the air supply unit 40 and room temperature humidified hydrogen gas was supplied from the fuel supply unit 50. Then, a value of 1.12 V or more was obtained as the open electromotive force.

  As shown in Table 1, cells # 101 to 143 in which the intermediate layer 14 is formed have improved adhesion than the cell # 100 in which the intermediate layer 14 is not formed. Moreover, cell # 101-143 obtained the interface resistance lower than cell # 100, ie, the more superior electrode specification. This is because the adhesion of the air electrode 13 is improved, so that the micro peeling of the air electrode 13 is suppressed, and the interface between the electrolyte layer 11 and zirconia can be more firmly adhered, and the intermediate layer 14 provided at this interface. This is considered to be because the composition of is close to the highly active air electrode 13. As described above, according to the present embodiment, the formation of the intermediate layer 14 improves the adhesion of the air electrode 13 to the zirconia-based electrolyte layer 11 and lowers the air electrode interface resistance. The value could be stabilized.

[Third Embodiment]
Next, a third embodiment of the present invention will be described. In the present embodiment, the same components as those in the second embodiment are denoted by the same names and reference numerals, and description thereof will be omitted as appropriate.

In this embodiment, in the cells # 100 to 143 of the second embodiment described above, the material of the electrolyte layer 11 is changed from YSZ to SSZ (0.9ZrO ₂ −0.1Sc ₂ O ₃ ), and the air electrode 13 Cells # 200 to 243 were used in which the material was changed from LSM to LSF (La _0.8 Sr _0.2 FeO ₃ ) composed of La and Sr at the A site and Fe at the B site. Using the cells # 200 to 243, the same test as in the second embodiment was performed. The test results are shown in Table 2.

  As shown in Table 2, also in the present embodiment, the cells # 201 to # 243 provided with the intermediate layer 14 have improved adhesion as compared to the cell # 200 where the intermediate layer 14 is not formed. The same or good characteristics were obtained in the interface resistance.

[Fourth Embodiment]
Next, a fourth embodiment of the present invention will be described. In the present embodiment, the same components as those in the first and second embodiments are denoted by the same names and reference numerals, and description thereof will be omitted as appropriate.

This embodiment, in the cell # 100-143 of the second embodiment described above, SASZ material of the electrolyte layer 11 from _{YSZ (0.89ZrO 2 -0.1Sc 2 O 3} -0.01Sc 2 O 3 ), The material of the air electrode 13 is changed from LSM to LNF (LaNi _0.6 Fe _0.4 O ₃ ) composed of A site La and B site Ni and Fe, respectively, to cells # 300 to 343 It is. Using the cells # 300 to 343, the same test as in the second embodiment was performed. The test results are shown in Table 3.

  As shown in Table 3, also in the present embodiment, the cells # 301 to # 343 provided with the intermediate layer 14 have improved adhesion as compared to the cell # 300 where the intermediate layer 14 is not formed. The same or good characteristics were obtained in the interface resistance.

[Fifth Embodiment]
Next, a fifth embodiment of the present invention will be described. In the present embodiment, the same components as those in the second embodiment are denoted by the same names and reference numerals, and description thereof will be omitted as appropriate.

In this embodiment, in the cells # 100 to 143 of the second embodiment described above, the material of the electrolyte layer 11 is changed from YSZ to YSZ-YDC (0.9 {0.9ZrO ₂ -0.1Y ₂ O ₃ }). +0.1 {Ce _0.8 Y _0.2 O ₂ }), and the material of the air electrode 13 is made of LSCF (La _0.8 Sr _0.2 Fe _0.8 Co _0.2 O made of LSM, A site is La and Sr, and B site is Fe and Co). _The cells replaced with ₃ ) are cells # 400 to 443, respectively. Here, the intermediate layer 14 was only dried at 400 ° C., and after the air electrode 13 was applied, the air electrode 13 and the intermediate layer 14 were simultaneously fired at 1000 ° C. for 2 hours. Using the cells # 400 to 443, the same test as in the second embodiment was performed. The test results are shown in Table 4.

  As shown in Table 4, also in the present embodiment, the cells # 401 to # 443 provided with the intermediate layer 14 have improved adhesion as compared to the cell # 400 where the intermediate layer 14 is not formed. The same or good characteristics were obtained in the interface resistance.

[Sixth Embodiment]
Next, a sixth embodiment of the present invention will be described. In the present embodiment, the same components as those in the second embodiment are denoted by the same names and reference numerals, and description thereof will be omitted as appropriate.

In the present embodiment, in the second embodiment described above, a transition metal composed of any one of Co, Fe, Mn, and Ni, a metal element corresponding to the same YSZ composition as the electrolyte layer 11, and a predetermined mixing ratio are used. The solution mixed in (1) was applied onto the electrolyte layer 11 by spin coating, dried at 400 ° C., and then baked at 1000 ° C. for 4 hours, thereby forming an intermediate layer 14 having a thickness of 0.3 μm. Cells with different components or mixing ratios of the intermediate layer 14 formed by such a method are designated as cells # 501 to 531, respectively. Using the cells # 501 to 531, a test similar to that of the second embodiment was performed. The test results are shown in Table 5. In Table 5, the composition of the intermediate layer means a molar mixing ratio (ratio of MO _X and (Zr + Y) O ₂ ). For comparison, Table 5 also shows cell # 100 used as a reference cell in the second embodiment.

  As shown in Table 5, also in the present embodiment, the cells # 501 to # 531 provided with the intermediate layer 14 have improved adhesion as compared to the cell # 100 where the intermediate layer 14 is not formed. The same or good characteristics were obtained in the interface resistance.

[Seventh Embodiment]
Next, a seventh embodiment of the present invention will be described. In the present embodiment, the same components as those in the second and third embodiments are denoted by the same names and reference numerals, and description thereof will be omitted as appropriate.

In the present embodiment, in the third embodiment described above, a transition metal composed of any one of Co, Fe, Mn, and Ni, a metal element corresponding to the same SSZ composition as the electrolyte layer 11, and a predetermined mixing ratio. The solution mixed in (1) was applied onto the electrolyte layer 11 by spin coating, dried at 400 ° C., and then baked at 1000 ° C. for 4 hours, thereby forming an intermediate layer 14 having a thickness of 0.3 μm. Cells having different components or mixing ratios of the intermediate layer 14 formed by such a method are referred to as cells # 601 to 631, respectively. Using the cells # 601 to 631, tests similar to those in the second embodiment were performed. The test results are shown in Table 6. In Table 6, the composition of the intermediate layer means a molar mixing ratio (ratio of MO _X and (Zr + Sc + Al) O ₂ ). For comparison, Table 6 also shows cell # 200 used as a reference cell in the third embodiment.

  As shown in Table 6, also in the present embodiment, the cells # 601 to # 631 provided with the intermediate layer 14 have improved adhesion as compared to the cell # 200 where the intermediate layer 14 is not formed. The same or good characteristics were obtained in the interface resistance.

[Eighth Embodiment]
Next, an eighth embodiment of the present invention will be described. In the present embodiment, the same components as those in the second and fourth embodiments are denoted by the same names and reference numerals, and description thereof will be omitted as appropriate.

In the present embodiment, in the above-described fourth embodiment, a transition metal made of any one of Co, Fe, Mn, and Ni, a metal element corresponding to the same composition of SASZ as the electrolyte layer 11, and a predetermined mixing ratio are used. The solution mixed in (1) was applied onto the electrolyte layer 11 by spin coating, dried at 400 ° C., and then baked at 1000 ° C. for 4 hours, thereby forming an intermediate layer 14 having a thickness of 0.3 μm. Cells having different components or mixing ratios of the intermediate layer 14 formed by such a method are referred to as cells # 701 to 731, respectively. A test similar to that of the second embodiment was performed using such cells # 701 to 731. The test results are shown in Table 7. In Table 7, the composition of the intermediate layer means a molar mixing ratio (ratio of MO _X and (Zr + Sc + Al) O ₂ ). For comparison, Table 7 also shows cell # 300 used as a reference cell in the fourth embodiment.

  As shown in Table 7, also in the present embodiment, the cells # 701 to # 731 provided with the intermediate layer 14 have improved adhesion as compared to the cell # 300 where the intermediate layer 14 is not formed. The same or good characteristics were obtained in the interface resistance.

[Ninth Embodiment]
Next, a ninth embodiment of the present invention will be described. In the present embodiment, the same components as those in the second and fifth embodiments are denoted by the same names and reference numerals, and description thereof will be omitted as appropriate.

In the present embodiment, in the fifth embodiment described above, the transition metal composed of any one of Co, Fe, Mn, and Ni and the same YSZ-YDC (0.9 {0.9ZrO ₂ − 0.1Y ₂ O ₃ } +0.1 {Ce _0.8 Y _0.2 O ₂ }) and a solution mixed with a metal element corresponding to the composition at a predetermined mixing ratio are applied onto the electrolyte layer 11 by a spin coating method, and 400 ° C. The air electrode 13 and the intermediate layer 14 were simultaneously baked at 1000 ° C. for 2 hours after application of the air electrode 13 to form an intermediate layer 14 having a thickness of 0.3 μm. Cells having different components or mixing ratios of the intermediate layer 14 formed by such a method are referred to as cells # 801 to 831, respectively. Using the cells # 801 to 831, the same test as in the second embodiment was performed. The test results are shown in Table 8. In Table 8, the composition of the intermediate layer means a molar mixing ratio (a ratio of MO _X to (Zr + Ce + Y + Al) O ₂ ). For comparison, Table 8 also shows cell # 400 used as a reference cell in the fifth embodiment.

  As shown in Table 8, also in the present embodiment, the cells # 801 to # 831 provided with the intermediate layer 14 have improved adhesion as compared to the cell # 400 where the intermediate layer 14 is not formed. The same or good characteristics were obtained in the interface resistance.

[Tenth embodiment]
Next, a tenth embodiment of the present invention will be described. In the present embodiment, the same components as those in the second, fourth, and eighth embodiments are denoted by the same names and reference numerals, and description thereof will be omitted as appropriate.

  In the present embodiment, in the eighth embodiment, the cell # 901 to 905 is obtained by changing the thickness of the intermediate layer of the cell # 704 from 0.05 to 2 μm. Cell # 911-915 was obtained by changing the thickness of the intermediate layer of cell # 714 to 0.05-2 μm. Using the cells # 901 to 915, the same test as in the second embodiment was performed. The test results are shown in Table 9. For comparison, Table 9 also shows cell # 300 used as a reference cell in the fourth embodiment.

  As shown in Table 9, also in the present embodiment, the cells # 901 to # 915 provided with the intermediate layer 14 have improved adhesion as compared to the cell # 300 where the intermediate layer 14 is not formed. The same or good characteristics were obtained in the interface resistance.

[Eleventh embodiment]
Next, an eleventh embodiment of the present invention will be described. In the present embodiment, the same components as those in the fourth embodiment are denoted by the same names and reference numerals, and description thereof will be omitted as appropriate.

In the present embodiment, a cell in which the intermediate layer 14 is formed by the RF sputtering method using Co ₃ O ₄ or Fe ₂ O ₃ as a target in the above-described fourth embodiment cells # 302 to 304, 312 to 314, These are cells # 1001 to 1013, respectively. Using the cells # 1001 to 1013, the same test as in the fourth embodiment was performed. The test results are shown in Table 10. For comparison, Table 10 also shows the cell # 300 used as a reference cell in the fourth embodiment.

  As shown in Table 10, also in the present embodiment, the cells # 1001 to # 1013 provided with the intermediate layer 14 have improved adhesion as compared to the cell # 300 where the intermediate layer 14 is not formed. The same or good characteristics were obtained in the interface resistance.

[Twelfth embodiment]
Next, a twelfth embodiment of the present invention will be described. In the present embodiment, the same components as those in the eleventh embodiment are denoted by the same names and reference numerals, and description thereof will be omitted as appropriate.

In this embodiment, in the eleventh embodiment described above, a thickness having a predetermined composition is obtained by two-dimensional simultaneous RF sputtering using a SASZ target and Co ₃ O ₄ or a SASZ target and Fe ₂ O _3. An intermediate layer 14 having a thickness of 0.2 μm was formed. Cells having different components or mixing ratios of the intermediate layer 14 formed by such a method are designated as cells # 1101 to 1114, respectively. A test equivalent to that of the eleventh embodiment was performed using such cells # 1101 to 1114. The test results are shown in Table 11. In Table 11, the composition of the intermediate layer is obtained by changing the mixing ratio of SASZ and Mo _x (M = Co, Fe) as (Zr + Sc + Al): M. For comparison, Table 11 also shows cell # 300 used as a reference cell in the fourth embodiment.

  As shown in Table 11, also in the present embodiment, the cells # 1101 to # 1114 provided with the intermediate layer 14 have improved adhesion as compared to the cell # 300 where the intermediate layer 14 is not formed. The same or good characteristics were obtained in the interface resistance.

It is sectional drawing which shows the structure of the single cell of the solid oxide fuel cell of this invention. (A) The top view which shows the structure of the single cell of the solid oxide fuel cell of this invention, (b) It is sectional drawing which shows the structure of the single cell of the solid oxide fuel cell of this invention. It is principal part sectional drawing which shows the structure of the fuel cell incorporating the single cell of FIG. It is a schematic diagram which shows the structure of the single cell for an adhesive force test.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Single cell, 2 ... Electrolyte layer, 3 ... Air electrode, 4 ... Fuel electrode, 5 ... Intermediate layer, 10 ... Single cell, 11 ... Electrolyte layer, 12 ... Fuel electrode, 13 ... Air electrode, 14 ... Intermediate layer, DESCRIPTION OF SYMBOLS 15 ... Reference electrode, 16 ... Platinum mesh current collector, 20 ... Fuel cell, 30 ... Cell cover, 31 ... Seal, 40 ... Air supply part, 50 ... Fuel supply part, 60 ... Terminal, 70 ... Reference terminal.

Claims (8)

In a solid oxide fuel cell in which an air electrode and a fuel electrode are provided on both surfaces of an electrolyte layer, and an intermediate layer is provided between the electrolyte layer and the air electrode,
The electrolyte layer is composed of rare earth added zirconia,
The air electrode is composed of a metal oxide having a perovskite structure composed of a first metal composed of La or La and Sr, and a second metal composed of at least one element of Fe, Co, Mn, and Ni. And
The intermediate layer is composed of an oxide containing at least one element of Fe, Co, Mn, and Ni. A solid oxide fuel cell, wherein: 2. The solid oxide fuel cell according to claim 1, wherein a thickness of the intermediate layer is not less than 0.01 μm and not more than 1 μm. 2. The solid oxide according to claim 1, wherein the intermediate layer is composed of a mixed oxide containing rare earth-added zirconia and at least one element of Fe, Co, Mn, and Ni. Physical fuel cell. The solid oxide fuel cell according to claim 3, wherein the rare earth-added zirconia is mixed at a ratio of 1 to 80 wt%. 5. The solid oxide fuel cell according to claim 3, wherein the intermediate layer has a thickness of 0.02 μm to 2 μm. A method for producing a solid oxide fuel cell in which an air electrode and a fuel electrode are provided on both surfaces of an electrolyte layer, and an intermediate layer is formed between the electrolyte layer and the air electrode,
An intermediate layer forming step of applying a solution containing any one or more elements of Fe, Co, Mn, and Ni onto the electrolyte layer made of rare earth-added zirconia and firing to form the intermediate layer;
A metal oxide having a perovskite structure made of a first metal made of La or La and Sr and a second metal made of at least one element of Fe, Co, Mn, and Ni is formed on the intermediate layer. And an air electrode forming step of forming an air electrode by applying and baking a slurry containing the solid oxide fuel cell. A method for producing a solid oxide fuel cell in which an air electrode and a fuel electrode are provided on both surfaces of an electrolyte layer, and an intermediate layer is formed between the electrolyte layer and the air electrode,
Applying a solution containing at least one element of Fe, Co, Mn, and Ni onto the electrolyte layer made of rare earth-added zirconia and drying to form a thin film; and
A metal oxide having a perovskite structure including a first metal composed of La or La and Sr and a second metal composed of at least one element of Fe, Co, Mn, and Ni is included on the thin film. And a formation step of forming the air electrode and the intermediate layer by applying a slurry and firing the slurry. A method for producing a solid oxide fuel cell, comprising: A method for producing a solid oxide fuel cell in which an air electrode and a fuel electrode are provided on both surfaces of an electrolyte layer, and an intermediate layer is formed between the electrolyte layer and the air electrode,
An intermediate layer forming step of forming the intermediate layer made of an oxide containing at least one element of Fe, Co, Mn, and Ni on the electrolyte layer made of rare earth-added zirconia by a vacuum film forming method; ,
A metal oxide having a perovskite structure made of a first metal made of La or La and Sr and a second metal made of at least one element of Fe, Co, Mn, and Ni is formed on the intermediate layer. And an air electrode forming step of forming an air electrode by applying and baking a slurry containing the solid oxide fuel cell.

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