JP5487042B2 - Solid oxide fuel cell, oxide-coated ceramic particles for solid oxide fuel cell, and method for producing solid oxide fuel cell - Google Patents

Description

  Embodiments described herein relate generally to a solid oxide fuel cell, oxide-coated ceramic particles for a solid oxide fuel cell, and a method for manufacturing a solid oxide fuel cell.

A solid oxide fuel cell (SOFC) is a next-generation clean fuel cell that can reduce the resistance acting inside the cell due to its high operating temperature (700-1000 ° C), realizing high power generation efficiency and low CO ₂ generation. It is expected as a powerful power generation system.

The SOFC fuel electrode is generally formed by cermet of ceramic particles having oxide ion conductivity and metal particles which are a catalyst and have electronic conductivity. Nickel particles that have high catalytic activity at high temperatures and are useful as reforming catalysts for hydrocarbon fuels such as methane are used for the metal particles that are catalysts. For the oxide ion conductive particles, ZrO ₂ (YSZ) stabilized with Y ₂ O ₃ having high oxide ion conductivity at a high temperature is used.

  The electrochemical reaction at the fuel electrode occurs at the interface of hydrogen gas as the fuel, nickel as the catalyst and electronic conductor, and oxide ion conductor, that is, a three-phase interface. Therefore, increasing the amount of the three-phase interface is the key to improving the fuel electrode performance.

  When mixed conductive particles having both oxide ions and electronic conductivity are used instead of YSZ having only oxide ion conductivity, this three-phase interface is increased, and the performance as a fuel electrode is further improved. On the other hand, the nickel particles as a catalyst can increase the three-phase interface (reaction field) as the particle size is reduced and the number is increased, that is, the catalyst specific surface area is increased, and high catalytic activity is expected. However, when the nickel particle size is reduced, there is a problem that the particles are easily aggregated and sintered under a use environment of a high temperature reducing atmosphere.

  On the other hand, in recent years, higher output has been demanded.

JP 2009-64640 A

J. et al. Electrochem. Soc. 141, [2], 342-346, 1994.

  It is an object of the present invention to provide a solid oxide fuel cell capable of increasing output and a method for manufacturing the same.

  The solid oxide fuel cell of the embodiment includes a solid electrolyte layer having oxygen ion conductivity, and a porous electrode formed on one main surface side of the solid electrolyte layer and made of a first electron-ion mixed conductive material. Formed of at least one part of the surface of the porous sintered body and the porous sintered body and comprising at least one of a second electron-ion mixed conductive material and an oxygen ion conductive material, And a fuel electrode including ceramic particles coated with an oxide film in which particles are dispersed and supported. In addition, an air electrode formed on the other main surface side of the solid electrolyte layer is provided.

It is sectional drawing which shows schematic structure of the solid oxide fuel cell in embodiment. It is sectional drawing which expands and shows the fuel electrode of the solid oxide fuel cell shown in FIG. FIG. 3 is an enlarged view showing a part of a fuel electrode shown in FIG. 2. It is an XRD pattern of the complex oxide film obtained in the example. 4 is a SEM photograph of a fuel electrode obtained in Example 2.

  Hereinafter, embodiments will be described in detail with reference to the drawings.

(Solid oxide fuel cell)
FIG. 1 is a cross-sectional view showing a schematic configuration of a solid oxide fuel cell in the present embodiment, and FIG. 2 is an enlarged cross-sectional view showing a fuel electrode of the solid oxide fuel cell shown in FIG. . FIG. 3 is an enlarged view of a part of the fuel electrode shown in FIG.

  A solid oxide fuel cell 10 shown in FIG. 1 includes a solid electrolyte layer 11 exhibiting oxygen ion conductivity, a fuel electrode 12 formed on the main surface 11A side of the solid electrolyte layer 11, and a solid electrolyte layer 11. It has the air electrode 13 formed in the main surface 11B side opposite to the main surface 11A. Further, current collectors 15 and 16 are formed on the main surfaces 12A and 13A side of the fuel country 12 and the air electrode 13 opposite to the solid electrolyte layer 11 via current collecting layers 17 and 18, respectively. .

  In this embodiment, the current collecting layers 17 and 18 and the current collectors 15 and 16 are not essential components, but by providing such a current collecting layer and current collector, a solid oxide fuel is provided. The electric power generated in the battery 10 can be efficiently extracted outside.

The solid electrolyte layer 11 can be composed of, for example, stabilized zirconia. In this case, examples of the stabilizer include Y ₂ O ₃ , Sc ₂ O ₃ , Yb ₂ O ₃ , Gd ₂ O ₃ , Nd ₂ O ₃ , CaO, and MgO. These stabilizers are used as a solid solution in zirconia. Moreover, it can replace with stabilized zirconia and can comprise perovskite type oxides, such as LaSrGaMg oxide, LaSrGaMgCo oxide, LaSrGaMgCoFe oxide, LaSrGaMgCoFe oxide. Furthermore, a ceria-based electrolyte solid solution in which Sm ₂ O ₃ , Gd ₂ O ₃ , Y ₂ O ₃ , La ₂ O _{3 and the} like are dissolved in CeO ₂ can also be used. However, the solid electrolyte layer 11 is not limited to these materials, and may be composed of other materials.

  In addition, although the thickness of the solid electrolyte layer 11 can be arbitrarily set according to the objective, it can be set as the range of 0.01 mm-0.5 mm, for example.

As an example, 8 mol% Y ₂ O ₃ stabilized zirconia having a thickness of 0.01 mm can be used.

  As shown in FIGS. 2 and 3, the fuel electrode 12 includes a porous sintered body 121 made of a first electron-ion mixed conductive material, and ceramic particles 122 formed on at least a part of the surface thereof. It consists of and. On the surface of the ceramic particle 122, an oxide film 123 in which metal particles 124 are dispersedly supported is formed. In the ceramic particles 122, the metal particles 124 are in contact with the ceramic particles 122 and protrude from the oxide film 123. That is, in the fuel electrode 12 shown in FIGS. 2 and 3, the porous sintered body 121 has a skeleton, and the metal particles 124 dispersed and supported on the oxide film 123 of the ceramic particles 122 attached and formed on the surface thereof. Functions as a catalyst.

The porous sintered body 121 is made of a first electron-ion mixed conductive material. Specifically, it can be composed of at least one selected from the group consisting of _Sm 2 _{O 3} doped _CeO 2, _Gd 2 _{O 3} doped CeO _2, and _Y 2 _{O 3} doped CeO _2. In this case, since the surface of the porous sintered body 121 becomes an interface between the electronic conductor and the oxide ion conductor, a fuel gas such as hydrogen gas in the solid oxide fuel cell 10 shown in FIG. And the amount of the interface of the oxide ion conductor, that is, the three-phase interface is increased. Therefore, the electrochemical reaction in the fuel electrode 12 is promoted, and the output characteristics of the solid oxide fuel cell 10 can be improved.

The ceramic particles 122 are also at least one oxygen ion conductive zirconium oxide selected from the group consisting of Y ₂ O ₃ , Sc ₂ O ₃ , and Yb ₂ O ₃ and / or Sm ₂ O ₃ doped CeO _2. , _Gd 2 _{O 3} doped CeO _2, and _Y 2 _{O 3} at least one second electronic selected from the group consisting of doped CeO ₂ - and a ion mixed conductive material. In this case, since the surfaces of the ceramic particles 122 serve as an interface between the oxide ion conductor and / or the electronic conductor, a fuel gas such as hydrogen gas in the solid oxide fuel cell 10 shown in FIG. The amount of the oxide ion conductor interface, that is, the amount of the three-phase interface is increased. Therefore, the electrochemical reaction in the fuel electrode 12 is promoted, and the output characteristics of the solid oxide fuel cell 10 can be improved.

  The ceramic particles 122 have the same effect whether they are zirconium oxide or cerium oxide. However, when the ceramic particles 122 are taken into the porous sintered body 121 during production, the ceramic particles 122 are also formed inside the particles. It is more preferable to use a cerium oxide having electron-ion mixed conductivity.

  Furthermore, the metal particles 124 have a size of about several nm to 200 nm, and are dispersedly supported on the oxide film 123 on the surface of the ceramic particles 122 as described above. That is, since the fine metal particles 124 of about several nm to 200 nm are supported and fixed on the oxide film 123, aggregation and sintering with respect to the metal particles 124 are unlikely to occur later, and the particle size becomes nonuniform. This does not cause a problem. That is, since the fine metal particles 124 of several nm to 200 nm exist stably and function as a catalyst, the electrochemical reaction at the fuel electrode 12 is promoted as the substantial surface area of the catalyst increases. As a result, the output characteristics of the solid oxide fuel cell 10 can be improved.

  Note that the thickness of the oxide film 122 is preferably in the range of, for example, several nm to several tens of nm so that the metal particles 123 having the above-described size can be exposed from the oxide film 122.

  As a result, in the solid oxide fuel cell 10 according to the present embodiment, oxidation of the porous sintered body 121 made of the electron-ion mixed conductive material, the ceramic particles 122, and the ceramic particles 122 formed on the surface thereof is performed. Along with the effect of promoting the electrochemical reaction by the metal particles 124 dispersedly supported on the material film 123, sufficiently high output characteristics can be obtained as compared with the conventional case.

  The size of the ceramic particles 122 (second ceramic particles) is, for example, in the range of 0.1 μm to 1.0 μm, and the electron-ion mixed conductive particles 121 (first ceramic particles) used for forming the porous sintered body. It is characterized by being smaller. The basic structure is a porous sintered body made up of an electron-ion mixed conductor to the last, thereby forming a path for electron and ion conduction reliably.

  The number of second ceramic particles 122 is greater than the number of first ceramic particles 121 used to form the porous sintered body. And it is preferable that the ratio for which a 2nd ceramic particle accounts among the sintered compact parts except the pore in the electrode finally obtained is the range of 1-60 volume%. When the proportion of the second ceramic particles is smaller than 1% by volume, the amount of the metal particles 124 as the catalyst is too small to cause a sufficient electrochemical reaction. On the other hand, when the proportion of the second ceramic particles is larger than 60% by volume in the porous sintered body, the oxide film 123 formed on the surface of the second ceramic particles 122 becomes a resistance, and sufficient oxygen ions In addition, there is a possibility that electrons cannot be conducted.

The dispersion density of the metal particles 124 in the ceramic particles 122 is, for example, 10 particles / μm ^{2 to} 10,000 particles / μm ² . Thereby, the catalytic effect of the metal particles 124 can be more effectively exhibited.

  The metal particles 124 are preferably composed of nickel, cobalt, iron, copper, or the like that functions as a catalyst in the electrochemical reaction. The oxide film 123 is preferably composed of aluminum oxide or magnesium oxide due to a manufacturing method described below.

  Further, as apparent from FIG. 2, the porous sintered body 121 has open pores, so that a fuel gas such as hydrogen or a generated gas smoothly flows through the porous sintered body 121, that is, the fuel electrode 12. Can diffuse. Therefore, the fuel gas can be supplied to the inside of the porous sintered body 121, the three-phase interface can be sufficiently increased, and the metal particles 123 formed inside the porous sintered body 121 are also in contact with each other. To be able to. As a result, the electrochemical reaction in the fuel electrode 12 can be further promoted, and sufficiently high output characteristics can be obtained.

  The porosity of the porous sintered body 121 is preferably 30% to 70%, for example. When the porosity is less than 30%, the generation ratio of the above-described open pores is reduced, and it is difficult to obtain the above-described effects. On the other hand, when the porosity exceeds 70%, the sintered density of the porous sintered body 121 decreases, the strength decreases, and the long-term reliability of the fuel electrode 12 decreases. That is, when the solid oxide fuel cell 10 shown in FIG. 1 is used for a long time, the fuel electrode 12 may be damaged, and its long-term reliability may not be sufficiently maintained.

  Further, it is preferable that the bonded portion of the porous sintered body 121 is firmly bonded without a defect such as a void. This can contribute to the above-described electrochemical reaction at the three-phase interface without hindering the movement of oxygen ions and electrons due to defects in the bonding portion.

  The thickness of the fuel electrode 12 can be set to 5 μm to 50 μm, for example. However, this is not the case when the electrolyte layer is thin and the air electrode is used as the support material.

  Although not particularly shown in FIG. 2, a coating layer made of an electron-ion mixed conductive material may be provided on the surface of the porous sintered body 121 to which the ceramic particles 122 are adhered. In this case, since the entire surface of the coating layer functions as the above-described three-phase interface, the three-phase interface is increased depending on the coating ratio of the coating layer, and the electrochemical reaction in the fuel electrode 12, that is, The output characteristics of the solid oxide fuel cell 10 can be improved.

The air electrode 13, can be composed of any material used as an oxygen electrode of an electrochemical cell than before, preferably, the general formula _{Ln 1-x A x BO 3} -δ (Ln = rare earth elements; A composite oxide represented by A = Sr, Ca, Ba; at least one of B = Cr, Mn, Fe, Co, and Ni) can be used. Such a composite oxide efficiently dissociates oxygen and has electronic conductivity. Therefore, it is possible to promote an electrochemical reaction between oxygen ions and hydrogen gas via the catalyst in the fuel electrode 12 described below, which contributes to higher output of the solid oxide fuel cell 10. .

  In addition, the thickness of the air electrode 13 can be 5 micrometers-100 micrometers, for example. However, this is not the case when the electrolyte layer is thin and the air electrode is used as the support material.

  The current collecting layer 17 includes a metal material such as nickel, cobalt, iron, copper, platinum, gold, silver, and the like and an electron-ion mixed conductive material that constitutes the porous sintered body 121. It can consist of a mixture. On the other hand, in the case of the current collection layer 18, it can be comprised from the mixture of metal materials, such as platinum, gold | metal | money, silver, and these metal materials and the electron-ion mixed conductive material which comprises the porous sintered compact 121. FIG. . The current collecting layers 17 and 18 reduce the resistance between the fuel electrode 12 and the air electrode 13 with respect to the current collectors 15 and 16 more reliably, and collect the generated power. It is for taking out more efficiently than the body.

  The current collectors 15 and 16 must be made of a material that does not oxidize under normal operating conditions. For example, in addition to precious metals such as gold, silver, and platinum, other base metals such as silver are used. What was coated with can be used. A ceramic material having conductivity can also be used. Further, a chromium-based alloy whose oxide film has conductivity can also be used.

(Method for producing solid oxide fuel cell)
Next, a method for manufacturing the solid oxide fuel cell in the embodiment will be described. In the present embodiment, the manufacturing method will be described in relation to the solid oxide fuel cell 10 shown in FIGS.

  First, a first ceramic particle made of a first electron-ion mixed conductive material, and a metal oxide made of at least one of a second electron-ion mixed conductive material and an oxygen ion conductive material The second ceramic particles coated with are mixed to prepare mixed ceramic particles. The first ceramic particles are made of the electron-ion mixed conductive material, and ceramic particles having a predetermined size can be used as they are.

  On the other hand, the second ceramic particles can be produced as follows. After preparing ceramic particles composed of an electron-ion mixed conductive material and / or an oxygen ion conductive material, the ceramic particles are immersed in metal nitrate or metal sulfate or suction filtered to obtain ceramic particles. The metal oxide is obtained from the metal nitrate or the metal sulfate by coating the surface with the metal nitrate or the metal sulfate and heating the obtained coating layer to the decomposition temperature or higher.

  In the mixed ceramic particles, the first ceramic particles are preferably mixed so that the particle size is larger than the second ceramic particles, and the number of the second ceramic particles is larger than the number of the first ceramic particles. . As a result, in the porous sintered body portion excluding pores in the fuel electrode, the proportion of the second ceramic particles is preferably 1 to 60% by volume.

  That is, by reducing the size of the second ceramic particles as compared with the size of the first ceramic particles, the bonding between the first ceramic particles is prevented from being divided by the second ceramic particles. Therefore, the disadvantage that sufficient oxygen ions and electrons cannot be conducted can be eliminated.

  Moreover, the electrochemical reaction by a catalytic action can be promoted by increasing the number of second ceramic particles. Furthermore, by setting the proportion of the second ceramic particles in the porous sintered body in the electrode to 1 to 60% by volume, the catalytic activity can be increased while forming a good electron-ion path. . If the proportion of the second ceramic particles is 1% by volume or less, sufficient reaction activity cannot be obtained, and if it is more than 60% by volume, the oxide film on the surface of the second ceramic particles becomes an electron-ion. Sufficient activity cannot be obtained due to hindering conduction.

  Next, mixed ceramic particles are laminated on the main surface 11 </ b> A of the solid electrolyte layer 11. Such a laminated arrangement can be performed, for example, by pasting mixed ceramic particles and screen printing the obtained paste. In addition, when ceramic particles cannot be laminated and arranged in a predetermined thickness by one screen printing, the above-described screen printing may be performed a plurality of times. In addition, it can replace with such screen printing and can substitute by methods, such as sheet forming, application | coating, and dipping.

  In the paste, when the porous sintered body 121 is formed through subsequent sintering, an organic substance such as styrene particles is used so that the porosity is, for example, in the above-described preferable range. A predetermined amount of system particles can be contained.

Next, the paste applied as described above is sintered to form a porous sintered body 121 that forms the skeleton of the fuel electrode 12 as shown in FIG. When the porous sintered body 121 is made of an electron-ion mixed conductive material (ceramic particles) such as the above-described Sm ₂ O ₃ -doped CeO ₂ , the sintering temperature is in the range of 1200 ° C. to 1400 ° C., for example. To do. The sintering atmosphere can be in the air.

  Next, the metal oxide covering the second ceramic particles is subjected to a reduction treatment, the metal contained in the metal oxide is precipitated in particles, and the deposited metal particles 124 are dispersed and supported. An oxide film 123 of the pole 12 is formed.

  Through the above operation, the ceramic particles in which the oxide film 123 in which the metal particles 124 are dispersedly supported are formed on at least a part of the surface of the porous sintered body 121 as shown in FIG. The target fuel electrode 12 formed by adhesion can be formed.

  In the present embodiment, the metal nitrate used when forming the second ceramic particles becomes the metal particles 124 dispersed and supported on the oxide film 123 through a subsequent reduction treatment, preferably The first metal nitrate containing at least one metal selected from the group consisting of nickel, cobalt, iron, and copper and the oxide film 123 itself are formed by the same reduction treatment, preferably aluminum and It is preferable to include a second metal nitrate containing at least one of magnesium. That is, the metal nitrate is preferably a complex metal nitrate composed of a first metal nitrate and a second metal nitrate.

  In this case, the metal oxide formed on the surface of the second ceramic particles becomes a composite metal oxide obtained by thermally decomposing the composite metal nitrate, and the composite metal oxide is formed of the first metal nitrate. A first metal oxide containing a metal that is easily reduced, i.e., nickel, cobalt, iron, and / or copper, and a metal that is not easily reduced, i.e., aluminum and / or magnesium, derived from the second metal nitrate. And a second metal oxide. Therefore, by obtaining such a composite metal oxide and subjecting it to a reduction treatment, the first metal oxide is easily reduced and the particles constituting the metal particles 124 are precipitated, while the second metal oxide is precipitated. The metal oxide remains as an oxide film 123 without being reduced.

  Therefore, according to the above aspect, the oxide film 123 in which the metal particles 124 are dispersed and supported by the reduction treatment can be easily formed on the ceramic particles 122.

  Similarly to the above, the metal sulfate also becomes the metal particles 124 dispersed and supported on the oxide film 123 through the subsequent reduction treatment, preferably from the group consisting of nickel, cobalt, iron, and copper. The first metal sulfate containing at least one selected metal and the second metal sulfate which preferably forms at least one of aluminum and magnesium, which constitutes the oxide film 123 itself through the subsequent reduction treatment. And a salt. Also in this case, the oxide film 123 in which the metal particles 124 are dispersedly supported by the reduction treatment can be easily formed based on the above-described effects.

  Next, the air electrode 13 can be formed by producing a paste containing ceramic particles constituting the air electrode on the main surface 11B of the solid electrolyte 11 by a conventional method, and screen-printing this paste.

  Next, if necessary, current collecting layers 17 and 18 are formed by a conventional method, and current collectors 15 and 16 are formed by a conventional method.

  The reduction treatment can be performed in advance at the stage of manufacturing the solid oxide fuel cell 10, but when the solid oxide fuel cell 10 is actually driven, it is post-treated with hydrogen gas used as a fuel gas. Can be done automatically.

This embodiment will be described in more detail with reference to examples.
In this embodiment, powder having a specific particle size is used as an example, but the present invention is not limited to this.

Example 1
First, nickel nitrate (Ni (NO ₃ ) ₂ · 6H ₂ O) and aluminum nitrate (Al (NO ₃ ) ₃ · 9H ₂ O) are mixed and dissolved at a molar ratio of 1: 2, and water is added. An aqueous solution of 1.0 mol / l complex nitrate was prepared. Next, 3 g of SDC powder (Sm _0.2 Ce _0.8 O ₂ ) having an average particle size of 0.15 μm was immersed in the aqueous solution of the composite nitrate, and then suction filtration was performed. After drying, heat treatment was carried out at 500 ° C. for 30 minutes, and the nitrate was thermally decomposed to produce ceramic particles coated with metal oxide (oxide-coated ceramic particles).

  Next, 0.15 g of the oxide-coated ceramic particles obtained as described above and 3.0 g of SDC particles having an average particle diameter of 1.4 μm (30: 1 in number ratio, electrode-sintered body of oxide-coated particles) The ratio of the oxide-coated particles to be contained is equivalent to 4% by volume), kneaded using water as a dispersion medium and pasted, and then screen-printed on a YSZ solid electrolyte plate (φ18 mm, thickness 0.5 mm) . By firing in the atmosphere at 1300 ° C. for 2 hours, a fuel electrode was obtained in which oxide-coated ceramic particles were adhered and formed on the surface of a porous sintered body obtained by sintering SDC particles.

  Next, after the current collector layer is screen-printed and baked on the surface of the fuel electrode, a platinum paste is screen-printed with a diameter of 6 mm on the counter electrode and baked in the atmosphere at 960 ° C. for 30 minutes to form an air electrode. Cell.

(Example 2)
Except that the mixing ratio of oxide-coated ceramic particles (average particle size 0.15 μm) and uncoated SDC particles (average particle size 1.4 μm) was 0.4 g: 2.0 g, all were prepared in the same manner as in the examples. Thus, a solid oxide fuel cell was obtained (number ratio of 160: 1, corresponding to the ratio of oxide-coated particles in the sintered body of the electrode: 16% by volume).

(Example 3)
Mixing ratio of oxide-coated ceramic particles (average particle size 0.5 μm) and uncoated SDC particles (average particle size 1.4 μm) in a number ratio of 30: 1, oxide-coated particles in the electrode sintered body A solid oxide fuel cell was obtained in the same manner as in Example 1 except that the ratio of was equivalent to 58% by volume.

(Example 4)
A mixed nitrate aqueous solution in which samarium nitrate (Sm (NO ₃ ) ₃ .6H ₂ O) and cerium nitrate (Ce (NO ₃ ) ₃ .6H ₂ O) were mixed at a molar ratio of 1: 4 to the mixed powder obtained in Example 2 Was added to 2 g of the mixed ceramic powder and kneaded with a plastic ball in a kneader. The paste was screen-printed on a YSZ solid electrolyte plate (φ18 mm, thickness 0.5 mm) and then fired in air at 1300 ° C. for 2 hours to sinter SDC particles. A fuel electrode having oxide-coated ceramic particles deposited on the surface was obtained.

  Next, after the current collector layer was screen-printed and baked on the surface of the fuel electrode in the same manner as in Example 1, platinum paste was screen-printed with a diameter of 6 mm on the counter electrode, and baked in the atmosphere at 960 ° C. for 30 minutes to form an air electrode A solid oxide fuel cell was obtained.

(Comparative Example 1)
Mixing ratio of oxide-coated ceramic particles (average particle size of 0.25 μm) and uncoated SDC particles (average particle size of 1.4 μm) in a 2: 1 ratio by number, oxide-coated particles occupying in the sintered body of the electrode A solid oxide fuel cell was obtained in the same manner as in Example 1 except that the ratio was adjusted so as to correspond to 0.3% by volume.

(Comparative Example 2)
Mixing ratio of oxide-coated ceramic particles (average particle diameter of 0.25 μm) and uncoated SDC particles (average particle diameter of 1.4 μm) in the number ratio of 1: 500, oxide-coated particles occupying in the sintered body of the electrode A solid oxide fuel cell was prepared in the same manner as in Example 1 except that the ratio was adjusted so as to correspond to 74% by volume.

(Comparative Example 3)
A solid oxide fuel was prepared in the same manner as in Example 1 except that SDC particles having an average particle size of 1.4 μm were used for the oxide-coated ceramic particles and 0.5 μm SDC particles were used for the uncoated ceramic particles. A battery cell was obtained.

In Examples 1 and 2, the EDX composition analysis of the film portion of the oxide-coated ceramic particles revealed that the oxide was composed of nickel and aluminum. In addition to this experiment, NiAl ₂ O ₄ was detected by X-ray diffraction analysis of the powder obtained by sintering the composite nitrate at 1300 ° C. (see FIG. 4). Since nickel and aluminum hardly dissolve in the SDC as the base material, the formed complex oxide film is considered to be NiAl ₂ O ₄ which is a spinel type oxide.

  FIG. 5 is a photograph of the structural structure of the fuel electrode produced in Example 2. Ceramic particles in which nickel fine particles having a size of several tens of nm are isolated and dispersed exist on the surface of the porous sintered body. Recognize. As a result of EDX analysis, it was also found that the layer supporting the nickel particles was an extremely thin aluminum oxide layer.

In addition, the maximum output density in the cell power generation test of Examples 1-4 and Comparative Examples 1-3 is put together in Table 1, and is shown. The operating conditions were H ₂ humidified at 30 ° C. at 50 mL / min, and 100 mL / min of dry air was introduced into the oxygen electrode at 900 ° C.

  Further, the detected ohmic resistance of the fuel electrode was almost zero in Examples 1 to 4 and Comparative Example 1. In Examples 1 and 2, a sintering network formed by large SDC particles was formed, an appropriate space was formed between the large particles, and hydrogen was diffused and water vapor as a product gas was smoothly diffused. Conceivable. On the other hand, in Comparative Example 1, it is considered that the amount of catalyst Ni present in the fuel electrode was extremely small and the reaction activity itself was small. In Comparative Examples 2 and 3, there is a possibility that the network of the porous sintered body by SDC is partially interrupted and the movement of electrons and ions by the coating oxide is hindered.

  As can be seen from Table 1, the cells of the solid oxide fuel cells in the examples have higher output performance than the cells of the solid oxide fuel cells obtained in the comparative examples.

  According to the embodiment described above, it is possible to provide a solid oxide fuel cell capable of increasing output and a method for manufacturing the same.

  As mentioned above, although several embodiment of this invention was described, these embodiment was posted as an example and is not intending limiting the range of invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

DESCRIPTION OF SYMBOLS 10 Solid oxide type fuel cell 11 Solid electrolyte layer 12 Fuel electrode 121 Porous sintered body 122 Ceramic particle 123 Oxide film 124 Metal particle 13 Air electrodes 15 and 16 Current collectors 17 and 18 Current collection layer

Claims (15)

A solid electrolyte layer having oxygen ion conductivity;
A porous sintered body formed on one main surface side of the solid electrolyte layer and made of a first electron-ion mixed conductive material, and formed on at least a part of the surface of the porous sintered body. And a fuel electrode comprising ceramic particles made of at least one of a second electron-ion mixed conductive material and an oxygen ion conductive material and coated with an oxide film in which metal particles are dispersedly supported. ,
An air electrode formed on the other main surface side of the solid electrolyte layer;
A solid oxide fuel cell comprising:   The solid oxide fuel cell according to claim 1, wherein the metal particles include at least one metal selected from the group consisting of nickel, cobalt, iron, and copper.   The solid oxide fuel cell according to claim 1, wherein the oxide film includes at least one of aluminum oxide and magnesium oxide. The first electron-ion mixed conductive material includes at least one selected from the group consisting of Sm ₂ O ₃ -doped CeO ₂ , Gd ₂ O ₃ -doped CeO ₂ , and Y ₂ O ₃ -doped CeO _2. The solid oxide fuel cell according to any one of claims 1 to 3, wherein the solid oxide fuel cell is characterized. The second electron-ion mixed conductive material includes at least one selected from the group consisting of Sm ₂ O ₃ -doped CeO ₂ , Gd ₂ O ₃ -doped CeO ₂ , and Y ₂ O ₃ -doped CeO _2. The solid oxide fuel cell according to any one of claims 1 to 4, wherein the solid oxide fuel cell is characterized. 5. The oxygen ion conductive material includes at least one selected from the group consisting of Y ₂ O ₃ , Yb ₂ O ₃ and Sc ₂ O _{3. 5.} Solid oxide fuel cell.   A coating layer made of a third electron-ion mixed conductive material formed on at least a part of the surface of the porous sintered body to which the ceramic particles are adhered is provided. The solid oxide fuel cell according to any one of claims 1 to 6.   For a solid oxide fuel cell, characterized in that it is made of at least one of an electron-ion mixed conductive material and an oxygen ion conductive material, and is coated with an oxide film in which metal particles are dispersedly supported. Oxide-coated ceramic particles.   The oxide-coated ceramic particle for a solid oxide fuel cell according to claim 8, wherein the metal particle protrudes from the oxide film.   The oxide coating for a solid oxide fuel cell according to claim 8 or 9, wherein the metal particles include at least one metal selected from the group consisting of nickel, cobalt, iron, and copper. Ceramic particles.   The oxide-coated ceramic particles for a solid oxide fuel cell according to any one of claims 8 to 10, wherein the oxide film contains at least one of aluminum oxide and magnesium oxide. The electron-ion mixed conductive material includes at least one selected from the group consisting of Sm ₂ O ₃ -doped CeO ₂ , Gd ₂ O ₃ -doped CeO ₂ , and Y ₂ O ₃ -doped CeO _2. The oxide-coated ceramic particles for a solid oxide fuel cell according to any one of claims 8 to 11. The oxygen ion conductive material _is characterized in that it comprises at least one selected from the group consisting of _{Y 2 O 3, Yb 2 O} 3 and _Sc 2 _{O 3,} according to any one of claims 8 to 12 Oxide-coated ceramic particles for solid oxide fuel cells. A first ceramic particle made of a first electron-ion mixed conductive material, and at least one of a second electron-ion mixed conductive material and an oxygen ion conductive material; A mixed ceramic particle having an average particle size larger than the average particle size of the second ceramic particles and a larger number of the second ceramic particles coated with the metal oxide than the number of the first ceramic particles. Adjusting the process,
The mixed ceramic particles are laminated on one main surface of the solid electrolyte layer having oxygen ion conductivity, and then the mixed ceramic particles are heated to be made of the first electron-ion mixed conductive material. Forming a porous sintered body constituting the fuel electrode, and attaching the second ceramic particles on at least a part of the surface of the porous sintered body;
Reducing the metal oxide and precipitating the metal contained in the metal oxide into particles;
Forming an air electrode on the other main surface side of the solid electrolyte layer;
A method for producing a solid oxide fuel cell, comprising:   The metal oxide includes a first metal oxide containing at least one metal selected from the group consisting of nickel, cobalt, iron, and copper, and a second metal oxide containing at least one of aluminum and magnesium. The metal particle includes a metal of the first metal oxide, and the oxide film includes an oxide of a metal in the second metal oxide. Of manufacturing a solid oxide fuel cell.

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