JP5146631B2 - SUBSTRATE FOR INTERCONNECTOR OF SOLID OXIDE FUEL CELL AND METHOD FOR PRODUCING INTERCONNECTOR OF SOLID OXIDE FUEL CELL - Google Patents

Description

  The present invention relates to a substrate for an interconnector of a solid oxide fuel cell, an interconnector of a solid oxide fuel cell, a method for manufacturing the interconnector, and a solid oxide fuel cell manufactured using the same.

  A solid oxide fuel cell (SOFC) is configured by electrically connecting a plurality of unit cells (cells) each composed of an electrolyte and a fuel electrode and an air electrode sandwiching the electrolyte as a unit. ing. This is because the voltage of the cell used in the solid oxide fuel cell is usually as low as about 0.7V.

  In the solid oxide fuel cell, a material that electrically connects a plurality of cells is an interconnector. In other words, the interconnector electrically connects the fuel electrode of one cell and the air electrode of another cell.

Conventionally, lanthanum chromite (LaCrO ₃ ) has been used as a material for an interconnector of a solid oxide fuel cell. This is because lanthanum chromite has excellent properties as an interconnector material because of its low electrical resistance. In addition, calcium titanate (CaTiO ₃ ) is known as a material for an interconnector of a solid oxide fuel cell having a low electric resistance.

  For example, in Japanese Patent Application Laid-Open No. 2-288162 of Patent Document 1 or Japanese Patent Application Laid-Open No. 8-268750 of Patent Document 2, a lanthanum chromite interconnector material is disclosed in Japanese Patent Application Laid-Open No. 11-86887 of Patent Document 3, Patent Japanese Laid-Open Patent Publication No. 11-54137 of Document 4 or Japanese Patent Laid-Open Publication No. 2003-323906 of Patent Document 5 discloses a calcium titanate-based interconnector material.

JP-A-2-288162 (Claims) JP-A-8-268750 (Claims) JP-A-11-86887 (Claims) JP-A-11-54137 (Claims) JP 2003-323906 A (claim)

  The solid oxide fuel cell interconnector must have a low electrical resistance. As the interconnector structure of the solid oxide fuel cell becomes denser, the electrical resistance becomes smaller. Conventionally, powdered lanthanum chromite particles have been used as a base material. However, since lanthanum chromite particles have a high sintering temperature, a compact body of powdered lanthanum chromite particles is about 1700 ° C. and extremely high temperature. Without firing at, an interconnector having a dense structure could not be obtained.

  In recent years, in solid oxide fuel cells, cells for a solid oxide fuel cell having a porous fuel electrode or air electrode have become mainstream. This is to increase the three-phase interface. In general, the electrolyte and the fuel electrode are obtained by firing a powdered metal oxide particle compact at about 1400 ° C., and the air electrode is a powder metal oxide particle compact approximately 1200 ° C. It is created by baking with.

  However, when the fuel electrode of one solid oxide fuel cell and the air electrode of another solid oxide fuel cell are interconnected by an interconnector, firing is performed at a high temperature of about 1700 ° C. Since the metal oxide constituting the fuel electrode and the air electrode is sintered, the porous structure is broken and the amount of the three-phase interface is reduced, resulting in a decrease in the output of the fuel cell. That is, when powdered lanthanum chromite particles are used as a substrate for an interconnector as in the prior art, there is a problem that the output of the fuel cell is reduced.

  For this reason, the current state of the art is that metal is used instead of metal oxide as the material for the interconnector of the solid oxide fuel cell. However, the use of metal as the interconnector material necessitates low-temperature operation, resulting in a problem that the output of the fuel cell is lowered.

  As other means, addition of various elements to lanthanum chromite or change to a substance other than lanthanum chromite has been performed, but the above problem has not been solved.

  Accordingly, an object of the present invention is to provide an interconnector for a solid oxide fuel cell that has a low electrical resistance and is manufactured by firing at a temperature of about 1400 ° C.

  As a result of intensive studies to solve the above-described problems in the prior art, the present inventors have found that the metal oxide precursor particles in an amorphous state have a crystal structure because the particle surface is extremely active. It has been found that sintering is performed at a lower temperature than the particles, and the present invention has been completed.

That is, the present invention (1) is composed of powdered metal oxide precursor particles having an average particle diameter of 0.01 to 1 μm obtained by oxidizing a metal or metal salt at 300 to 900 ° C. The present invention provides a substrate for an interconnector of a solid oxide fuel cell.

Moreover, this invention ( 2 ) obtains the powder-form metal oxide precursor particle | grains which are amorphous whose average particle diameter is 0.01-1 micrometer by oxidizing a metal or a metal salt at 300-900 degreeC, The amorphous powdery metal oxide precursor particles are molded, and then the amorphous powdered metal oxide precursor particles are fired to form a solid oxide fuel cell interconnector. The present invention provides a method for manufacturing an interconnector for a solid oxide fuel cell.

  ADVANTAGE OF THE INVENTION According to this invention, the interconnector of the solid oxide fuel cell manufactured by baking at the temperature of about 1400 degreeC with low electrical resistance can be provided.

  The substrate for an interconnector of the solid oxide fuel cell of the present invention comprises powdered metal oxide precursor particles that are amorphous. That is, the powdered metal oxide precursor particles are particles that do not have a specific crystal structure, that is, amorphous particles.

  The amorphous powdery metal oxide precursor particles are oxidized into a metal oxide having a specific crystal structure when oxidized. That is, the powdered metal oxide precursor particles are metal oxide precursors. The metal oxide related to the powdered metal oxide precursor particles that are amorphous is usually a metal oxide used in the production of an interconnector of a solid oxide fuel cell, such as lanthanum (La), chromium. (Cr), strontium (Sr), calcium (Ca), titanium (Ti), cerium (Ce), bismuth (Bi), yttrium (Y), zirconium (Zr), scandium (Sc), samarium (Sm), aluminum (Al), magnesium (Mg), gallium (Ga), niobium (Nb), tantalum (Ta), silicon (Si), gadolinium (Gd), ytterbium (Yb), iron (Fe), cobalt (Co), nickel It is an oxide of one or more metals selected from (Ni), praseodymium (Pr) and barium (Ba). Therefore, the powdered metal oxide precursor particles that are amorphous are metal oxide precursors related to the powdered metal oxide precursor particles that are amorphous.

  Specific examples of the metal oxide related to the powdery metal oxide precursor particles that are amorphous include lanthanum chromite, lanthanum calcium chromite, lanthanum strontium chromite, lanthanum calcium strontium chromite, calcium titanate, calcium cerium titanate, calcium Bismuth titanate, calcium cerium bismuth titanate, lanthanum magnesium titanate, lanthanum strontium titanate, lanthanum barium titanate, magnesium titanate, strontium titanate, barium titanate and the like can be mentioned. Among these, lanthanum chromite, lanthanum calcium chromite, lanthanum strontium chromite, lanthanum calcium strontium chromite, calcium titanate, and calcium cerium titanate are preferable in terms of low electrical resistance.

The metal oxide relating to the powdery metal oxide precursor particles that are amorphous is represented by the following general formula (1):
_{La (1-x1) A (} x1) Cr (1-y1) Mg (y1) O 3 (1)
(In the formula, A represents Ca or Sr, x1 is 0 to 0.5, and y1 is 0 to 0.15.)
Lanthanum chromite represented by the following general formula (2):
_{D (1-x2) E (} x2) Ti (1-y2) G (y2) O 3 (2)
(In the formula, D represents an alkaline earth metal, Mg, Ca, Sr or Ba, E represents La, Ce, Sm, Pr, Gd, Y or Sc, G represents Nb or Ta, and x2 represents 0. -0.8 and y2 is 0-0.2.)
The titanate represented by these is preferable at a point with small electrical resistance. In the formula (1), A may be a combination of Ca and Sr. In the formula (2), D is two or more of alkaline earth metals, Mg, Ca, Sr and Ba. E may be a combination of two or more of La, Ce, Sm, Pr, Gd, Y and Sc, and G may be a combination of Nb and Ta. When A is a combination of Ca and Sr, the value of x1 is the total value of Ca and Sr. When D is a combination of two or more of alkaline earth metals, Mg, Ca, Sr and Ba, the value of 1-x2 is the total value of alkaline earth metals, Mg, Ca, Sr and Ba Yes, when E is a combination of two or more of La, Ce, Sm, Pr, Gd, Y and Sc, the value of x2 is the sum of La, Ce, Sm, Pr, Gd, Y and Sc When G is a combination of Nb and Ta, the value of y2 is the total value of Nb and Ta.

  The average particle diameter of the powdery metal oxide precursor particles which are amorphous is 0.01 to 1 μm, preferably 0.05 to 0.1 μm. In the present invention, the average particle diameter is a value measured by particle size distribution measurement by a laser diffraction scattering method.

  A method for producing the amorphous powdered metal oxide precursor particles will be described. For example, in the case of lanthanum calcium chromite, when a mixture of lanthanum nitrate, calcium nitrate and chromium nitrate is oxidized at a temperature of about 1000 ° C. or higher, metal oxide particles having a specific crystal structure are obtained. On the other hand, when a mixture of lanthanum nitrate, calcium nitrate and chromium nitrate is oxidized at a temperature of about 300 to 900 ° C., particles having no crystal structure, that is, amorphous particles are obtained. That is, there are cases where metal oxide particles having a specific crystal structure are obtained and particles in an amorphous state are obtained depending on the oxidation temperature at the time of oxidizing the metal or metal salt.

  Whether the metal oxide particles have a specific crystal structure or are amorphous particles can be confirmed by X-ray diffraction analysis. When the metal oxide particles have a specific crystal structure, the X-ray diffraction analysis chart shows a sharp peak indicating the presence of the crystal structure, but on the other hand, when the particles are amorphous. In the X-ray diffraction analysis chart, a clear peak is not seen, or a broad broad peak is seen.

  That is, the powdered metal oxide precursor particles that are amorphous are produced by oxidizing a metal or metal salt, and the oxidation temperature at that time is set within a temperature range in which amorphous particles are generated. As a result, the amorphous powdery metal oxide precursor particles are produced. In other words, if the oxidation temperature is too high, metal oxide particles having a specific crystal structure are generated. Therefore, the powdered metal oxide precursor particles that are amorphous are at a temperature at which the metal or metal salt is oxidized. And a temperature lower than the temperature at which metal oxide particles having a specific crystal structure are formed is used as the oxidation temperature.

  Since the temperature range in which the amorphous particles are generated varies depending on the type of metal oxide, the oxidation temperature when oxidizing the metal or metal salt is selected for each type of metal oxide. Examples of the method for selecting the oxidation temperature include the following methods. First, a metal or metal salt is oxidized under several oxidation conditions with different oxidation temperatures to obtain a product. Each of the resulting products is then analyzed by X-ray diffraction analysis. Next, the relationship between the oxidation temperature and the peak of the obtained X-ray diffraction chart is obtained, and the oxidation temperature range in which amorphous particles are generated and the oxidation temperature range in which a metal oxide having a specific crystal structure is generated are grasped. To do. And the oxidation temperature at the time of oxidizing this metal or metal salt is selected from the oxidation temperature range which the amorphous particle | grains grasp | ascertained in this way produce | generate.

  The oxidation temperature when oxidizing the metal or metal salt to obtain the powdered metal oxide precursor particles that are amorphous is 300 to 900 ° C., and 300 to 800 ° C. in that the required energy is low. Is preferred.

  As an example of a method for producing the powdered metal oxide precursor particles that are amorphous, there is a method for producing powdered metal oxide precursor particles that are amorphous having a dispersion preparation step and a spray pyrolysis step. Can be mentioned.

  First, the dispersion preparation step will be described. The dispersion preparation step is a step of preparing a dispersion containing a metal salt.

The metal salt is lanthanum, chromium, strontium, calcium, titanium, cerium, bismuth, yttrium, zirconium, scandium, samarium, aluminum, magnesium, gallium, niobium, tantalum, silicon, gadolinium, ytterbium, iron, cobalt, nickel, praseodymium. And one or more metal salts selected from barium. The metal salt is not particularly limited and includes, for example, carbonate, sulfate, nitrate, chloride salt, and more specifically, lanthanum nitrate, chromium nitrate, calcium nitrate, lanthanum carbonate, strontium carbonate, Examples include calcium chloride and titanium chloride. The metal salt may be a combination of two or more metal salts having the same metal species, or a combination of two or more metal salts having different metal species.

  In the dispersion, the metal salt may exist as an aqueous solution dissolved in a dispersion medium, or may exist in a suspended state dispersed in the dispersion medium as a solid. When the metal salt is difficult to dissolve in water, an acid can be added to dissolve the metal salt.

  The content of the metal salt in the dispersion is 0.001 to 100 mol / L, preferably 0.001 to 10 mol / L, particularly preferably 0.01 to 10 mol / L.

  In addition, since the particle size of the powdered metal oxide precursor particles that are amorphous changes depending on the content of the metal salt in the dispersion, it can be obtained by appropriately selecting the content of the metal salt. The average particle diameter of the powdered metal oxide precursor particles that are amorphous can be controlled.

  The method for preparing the dispersion is not particularly limited, and examples thereof include a method in which the metal salt is dissolved in water to obtain an aqueous solution containing the metal salt.

  Next, the spray pyrolysis step will be described. The spray pyrolysis step is a step of spraying the dispersion liquid to a heating furnace to obtain powdered metal oxide precursor particles that are amorphous. In the spray pyrolysis step, the temperature of the heating furnace is set as follows: The temperature is such that amorphous metal oxide precursor particles are generated. In the spray pyrolysis step, the dispersion liquid droplets are sprayed onto the heating furnace to evaporate water in the dispersion liquid droplets, and the metal in the dispersion liquid droplets. The salt is oxidized.

  The method for spraying the dispersion liquid on the heating furnace is not particularly limited. For example, the dispersion liquid is pressurized with a pump and the droplets of the dispersion liquid are sprayed from the tip of a nozzle, or the method using an ultrasonic spray element. And a method of placing a droplet of the dispersion on a rotatable disk and flying the droplet by centrifugal force.

  The heating furnace may be a single-stage heating furnace or a multi-stage heating furnace in which a plurality of heating furnaces having different set temperatures are connected.

  The temperature of the heating furnace is appropriately selected depending on the type of metal constituting the metal salt. The method for selecting the heating furnace is to change the temperature of the heating furnace, perform the spray pyrolysis step, find the temperature range in which amorphous particles can be obtained from the X-ray diffraction chart of the product, and the temperature range The temperature of the heating furnace according to the method for producing the powdered metal oxide precursor particles that are amorphous is selected from the inside. In other words, when the temperature of the heating furnace is too high, metal oxide particles having a specific crystal structure are generated. Therefore, the metal oxide particles having a specific crystal structure are at a temperature at which the metal salt is oxidized. The temperature lower than the temperature at which is generated is defined as the temperature of the heating furnace.

  And the particle | grains which passed this heating furnace are collected using a filter etc., and the powdery metal oxide precursor particle | grains which are this amorphous are obtained.

  The amorphous powdered metal oxide precursor particles have high surface activity, and therefore have higher sinterability than metal oxide particles having a specific crystal structure.

  In order to connect two or more solid oxide fuel cell cells, the solid oxide fuel cell interconnector of the present invention is connected to the fuel electrode of one solid oxide fuel cell cell and another solid electrode. It is formed between the air electrodes of the oxide fuel cell. An embodiment of the interconnector of the solid oxide fuel cell of the present invention will be described with reference to FIG. FIG. 1 is a schematic cross-sectional view of a solid oxide fuel cell having an interconnector of the solid oxide fuel cell of the present invention. In FIG. 1, a solid oxide fuel cell 4a composed of a fuel electrode 1a, an electrolyte 2a and an air electrode 3a, and a solid oxide fuel cell 4b composed of a fuel electrode 1b, an electrolyte 2b and an air electrode 3b, This is a cell for a solid oxide fuel cell that is electrically connected by an interconnector (1-1). First, slurry 5 containing powdered metal oxide precursor particles that are amorphous is applied to the surface of the fuel electrode 1a of the solid oxide fuel cell 4a, and formed into a layer (1-2). ). Next, after drying the solid oxide fuel cell 4a on which the molded body of the slurry 5 is formed, the air of the solid oxide fuel cell 4b is formed on the dried molded body 6 of the slurry 5. The electrode 3b is brought into contact, and the solid oxide fuel cell 4a and 4b are fired while the dry molded body 6 and the air electrode 3b are in contact with each other (1-3 and 1-4). And by this baking, the metal oxide precursor particles which are amorphous in the dry molded body 6 are sintered to obtain an interconnector 7 having a dense structure, and the amorphous material in the dry molded body 6 is also obtained. The metal oxide precursor particles and the fuel electrode 1a or the air electrode 3b are sintered, and the interconnector 7 is electrically connected to the fuel electrode 1a and the air electrode 3b (1- 5). Further, by the firing, the amorphous metal oxide precursor particles become a metal oxide having a specific crystal structure.

  In this way, the fuel electrode 1a of the solid oxide fuel cell 4a and the air electrode 3b of the solid oxide fuel cell 4b are electrically connected by the interconnector 7. The solid oxide fuel cell 10 is manufactured.

  That is, the interconnector of the solid oxide fuel cell according to the present invention forms amorphous powdery metal oxide precursor particles, and then forms the amorphous powdered metal oxide precursor particles. Is a solid oxide fuel cell interconnector obtained by firing

  The powdered metal oxide precursor particles that are amorphous according to the interconnector of the solid oxide fuel cell of the present invention are amorphous powders that are related to the substrate for an interconnector of the solid oxide fuel cell of the present invention. The same as the metal oxide precursor particles.

  As a method for forming the powdered metal oxide precursor particles that are amorphous, for example, a slurry containing the powdered metal oxide precursor particles that are amorphous is prepared, and then the obtained slurry is And a method of forming the amorphous powdery metal oxide precursor particles by forming a film of the slurry by a screen printing method, a doctor plate method, or the like, and drying if necessary. . In this case, the slurry containing the powdered metal oxide precursor particles which are amorphous, includes a binder component such as polyvinyl butyral resin and ethyl cellulose, a plasticizer component such as di-n-butyl phthalate, and a nonionic type. A dispersant component such as a dispersant and an antifoam component such as octylphenyl ether can be contained. The slurry containing the powdered metal oxide precursor particles that are amorphous is mixed with the powdered metal oxide precursor particles that are amorphous in a solvent such as an organic solvent, alcohol, oil, and the like. If necessary, the binder component, the plasticizer component, the dispersant component, the antifoaming agent component, etc. are mixed, stirred, etc., and these components are dispersed or dissolved in the solvent. The

  The content of the amorphous powdery metal oxide precursor particles in the slurry containing the amorphous powdery metal oxide precursor particles is preferably 10 to 80% by mass, particularly preferably 40 to 40% by mass. 60% by mass.

  In addition, as a method of molding the amorphous powdered metal oxide precursor particles, the amorphous powdered metal oxide precursor particles are press-molded, and the amorphous powder The method of shape | molding the shape-like metal oxide precursor particle | grains is mentioned. The press molding is performed, for example, by placing the powdered metal oxide precursor particles that are amorphous into a mold and applying a load of about 10 to 200 MPa, preferably about 50 to 100 MPa.

  Next, by firing the amorphous powdered metal oxide precursor particle compact, the amorphous metal oxide precursor particles in the compact are sintered together, and a specific crystal structure is obtained. The solid oxide fuel cell interconnector is obtained by changing to the metal oxide particles. The firing temperature when firing the amorphous powdered metal oxide precursor particle compact is such that the amorphous powdered metal oxide precursor particle is a metal oxide having a specific crystal structure. It is above the temperature at which it changes to physical particles.

  The temperature at which the powdered metal oxide precursor particles that are amorphous changes to metal oxide particles having a specific crystal structure is the temperature of the metal oxide that is related to the powdered metal oxide precursor particles that are amorphous. It depends on the type. On the other hand, if the firing temperature is too high, the fuel electrode or air electrode connected by the interconnector of the solid oxide fuel cell of the present invention is easily sintered, and the amount of the three-phase interface tends to be reduced. Therefore, the firing temperature when firing the molded body of the powdered metal oxide precursor particles that are amorphous is the type of the metal oxide related to the amorphous powdered metal oxide precursor particles, and the present It is appropriately selected in consideration of the type or firing temperature of the fuel electrode or air electrode connected by the interconnector of the solid oxide fuel cell of the invention. The temperature range in which the amorphous powdered metal oxide precursor particles change to metal oxide particles having a specific crystal structure is obtained by firing under firing conditions in which the firing temperature is variously changed. And the peak intensity of the obtained X-ray diffraction chart, the temperature range in which the metal oxide precursor particles that are amorphous in the molded body change to metal oxide particles having a specific crystal structure is determined. , Is required by grasping.

And the firing temperature at the time of firing the compact of the powdered metal oxide precursor particles that are amorphous,
(I) The temperature of the amorphous powdered metal oxide precursor particles is not lower than the temperature at which the powdered metal oxide precursor particles change to metal oxide particles having a specific crystal structure,
And (ii) not higher than the firing temperature of the fuel electrode and the air electrode connected by the interconnector of the solid oxide fuel cell of the present invention,
It is preferable in that the porous structure of the fuel electrode and the air electrode is difficult to break when the molded body of powdered metal oxide precursor particles that are amorphous is fired. Specifically, for example, the temperature at which the amorphous powdered metal oxide precursor particles change to metal oxide particles having a specific crystal structure is 1000 ° C. or higher, and the firing temperature of the fuel electrode is 1400 ° C. When the firing temperature of the air electrode is 1200 ° C., the firing temperature when firing the amorphous powdered metal oxide precursor particle compact is preferably 1000 ° C. or more and 1400 ° C. or less.

As a method of firing the interconnector of the solid oxide fuel cell simultaneously with the firing of the electrode,
(1) First, a green body of a fuel electrode, a green body of an air electrode, and a green body of an interconnector base material are formed at predetermined positions. When firing the molded body, that is, a method of firing the fuel electrode, the air electrode and the interconnector simultaneously,
(2) First, the fuel electrode was fired, and then the fired fuel electrode, the unfired air electrode molded body, and the unfired interconnector base material molded body were formed at predetermined positions. A method of obtaining a molded body and then firing the molded body, that is, a method of simultaneously firing an air electrode and an interconnector;
There is. The firing temperature of the fuel electrode of the solid oxide fuel cell is usually 1300 to 1400 ° C., and the firing temperature of the air electrode is usually 1100 to 1300 ° C. Therefore, the amorphous powdered metal In the method (1), the firing temperature when firing the compact of the oxide precursor particles is preferably equal to or lower than the firing temperature of the fuel electrode. In the method (2), the firing temperature of the air electrode The following is preferable.

  On the other hand, if the firing temperature when firing the amorphous powdered metal oxide precursor particles is too higher than the firing temperature of the electrode, the porous structure of the electrode cannot be maintained, and the reaction active point Certain three-phase interfaces are reduced and battery performance is reduced.

  Therefore, the firing temperature when firing the amorphous powdered metal oxide precursor particle compact is usually 1000 to 1500 ° C, preferably 1000 to 1450 ° C, and particularly preferably 1100 to 1400 ° C. .

  The interconnector of the solid oxide fuel cell of the present invention has a density of 85 to 100%, preferably 90 to 100%. In the present invention, the density is a value measured by Archimedes method.

  The electrical conductivity of the interconnector of the solid oxide fuel cell of the present invention is 0.01 to 50 S / cm, preferably 0.1 to 50 S / cm.

  In the solid oxide fuel cell of the present invention, the anode of one solid oxide fuel cell and the air electrode of the other solid oxide fuel cell of the solid oxide fuel cell of the present invention. The fuel cell is electrically connected by an interconnector. That is, the solid oxide fuel cell of the present invention forms amorphous powdery metal oxide precursor particles, and then fires the amorphous powdered metal oxide precursor particle compacts. And a solid oxide fuel cell interconnector obtained in the above manner.

  As an example of the form of the solid oxide fuel cell of the present invention, as shown in FIG. 1, the powdered metal oxide precursor particles that are amorphous are formed on the fuel electrode of one solid oxide fuel cell. Is applied to the slurry molded body to form a slurry molded body, and if necessary, after drying, the slurry molded body or the dried molded body of the slurry is subjected to air of another one solid oxide fuel cell cell. Examples of the solid oxide fuel cell obtained by bringing the electrode into contact with each other and then firing the electrode include the fuel electrode of one solid oxide fuel cell and another solid oxide fuel cell. Examples include a solid oxide fuel cell obtained by sandwiching a powder-shaped metal oxide precursor particle press-molded body between the air electrodes of a fuel cell, and then firing it.

  Another example of the solid oxide fuel cell of the present invention is a cylindrical one.

  Since the substrate for an interconnector of the solid oxide fuel cell of the present invention is an amorphous powdery metal oxide precursor particle, the particle surface activity is extremely high. Therefore, the substrate for an interconnector of the solid oxide fuel cell of the present invention is easier to sinter than metal oxide particles having a specific crystal structure, and sinters at a low temperature. For example, when the metal oxide is lanthanum calcium chromite, the powdered metal oxide precursor particles that are amorphous are sintered at a temperature of about 1100 to 1400 ° C., while having a specific crystal structure. The lanthanum calcium chromite particles possessed do not sinter sufficiently unless the temperature is about 1600 to 1700 ° C.

  In addition, since the substrate for an interconnector of the solid oxide fuel cell of the present invention has a high particle surface activity, when firing at a low temperature of about 1100 to 1400 ° C., the solid oxide fuel cell of the present invention By using the interconnector base material, an interconnector having a high density can be obtained as compared with the case where metal oxide particles having a specific crystal structure are used as the base material. Therefore, the interconnector obtained by firing the substrate for an interconnector of the solid oxide fuel cell of the present invention has an electric resistance as compared with the interconnector obtained by firing metal oxide particles having a specific crystal structure. Is small.

  In addition, since the substrate for an interconnector of the solid oxide fuel cell of the present invention is easily sintered, it is easy to join the interconnector to the fuel electrode or the air electrode. Therefore, an interconnector obtained by sintering a substrate for an interconnector of a solid oxide fuel cell according to the present invention is more fuel-efficient than an interconnector obtained by firing metal oxide particles having a specific crystal structure. High bondability with electrode or air electrode.

  For these reasons, the solid oxide fuel cell of the present invention is less likely to reduce the amount of the three-phase interface during firing of the interconnector, and the interconnector is dense, that is, the electrical resistance of the interconnector is low. It is small and has high jointability between the interconnector, the fuel electrode and the air electrode.

  EXAMPLES Next, although an Example is given and this invention is demonstrated more concretely, this is only an illustration and does not restrict | limit this invention.

Example 1
(Preparation of spray solution)
Weighing 303.10 g of lanthanum nitrate hexahydrate, 400.16 g of chromium nitrate nonahydrate and 75.56 g of calcium nitrate tetrahydrate, putting them in 1000 mL of pure water, and heating to 50-80 ° C. Then, the mixture was dissolved by stirring with a stirrer to prepare a 1 mol / L solution of La _0.68 Ca _0.32 Cr _1.0 O ₃ . Then the _{La 0.68 Ca 0.32 Cr 1.0 O 3} 1mol / L of solution were diluted in _{10-fold, La 0.68 Ca 0.32 Cr 1.0 O} 3 of 0.1 mol / L A solution was prepared.

(Spray pyrolysis)
Next, the temperature of the electric furnace was set to 300 ° C., 500 ° C., 700 ° C., and 900 ° C. from the upstream side of the 0.1 mol / L solution of La _0.68 Ca _0.32 Cr _1.0 O ₃ , respectively. In addition, spraying at an air flow rate of 2 L / min in an electric furnace of an ultrasonic spray pyrolysis apparatus of a quadruple electric furnace, and trapping the particles that passed through the last stage electric furnace with a membrane filter made of Teflon (registered trademark). Collected to obtain particles A. When the particle A was observed with an electron microscope, the particle size was 0.2 to 1.0 μm.

(X-ray diffraction analysis)
As a result of X-ray diffraction analysis of the particle A, no diffraction peak indicating the presence of a specific crystal structure was observed in the obtained chart, and a broad and weak diffraction peak specific to the amorphous structure was observed. The particles A were heated in an electric furnace in an air atmosphere at 1000 ° C. or higher for 2 hours, and the particles were subjected to X-ray diffraction analysis. As a result, the obtained chart showed sharp and strong lanthanum calcium chromite. A diffraction pattern was observed. This indicates that the particles A were oxidized to be particles having a specific crystal structure by being heated in an air atmosphere.

(Baking)
The particles A were uniaxially pressed at a pressure of 65 MPa using a mold having a diameter of 30 mm to obtain a molded body of the particles A. Next, the molded body of the particles A was fired in an electric furnace at 1450 ° C. for 2 hours to obtain a fired body A. The density of the fired body A was 89.6%.

(Example 2)
(Preparation of spray solution)
The 0.1 mol / L solution of La _0.68 Ca _0.32 Cr _1.0 O ₃ prepared in Example 1 was further diluted 10 times, and La _0.68 Ca _0.32 Cr _1.0 O ₃ was diluted. Of 0.01 mol / L was prepared.

(Spray pyrolysis)
Instead of the 0.1 mol / L solution of the _{La 0.68 Ca 0.32 Cr 1.0 O 3} , and 0.01 mol / L solution of the _La 0.68 _Ca 0.32 _Cr 1.0 _{O 3} Except that, Particle B was obtained in the same manner as in Example 1. When the particle B was observed with an electron microscope, the particle size was 0.1 to 0.5 μm.

(X-ray diffraction analysis)
As a result of X-ray diffraction analysis of the particle B, no diffraction peak indicating the presence of a specific crystal structure was observed in the obtained chart, and a broad and weak diffraction peak specific to the amorphous structure was observed. Further, when the particles B were heated in an electric furnace in an air atmosphere at 1000 ° C. or higher for 2 hours, the particles were subjected to X-ray diffraction analysis. The obtained chart showed sharp and strong lanthanum calcium chromite. A diffraction pattern was observed. This indicates that the particles B were oxidized to be particles having a specific crystal structure by being heated in an air atmosphere.

(Baking)
A calcined product B was obtained in the same manner as in Example 1 except that the particles B were used instead of the particles A. The density of the fired body B was 91.0%.

(Comparative Example 1)
A commercially available La _0.68 Ca _0.32 Cr _1.0 O ₃ powder (manufactured by Seimi Chemical Co., Ltd.) was prepared. When the commercially available La _0.68 Ca _0.32 Cr _1.0 O ₃ powder was subjected to X-ray diffraction analysis, a sharp and strong lanthanum calcium chromite diffraction pattern was observed.

(Baking)
A calcined product C was obtained in the same manner as in Example 1 except that instead of the particles A, the commercially available La _0.68 Ca _0.32 Cr _1.0 O ₃ powder was used. The density of the fired body C was 84.0%.

(Example 3)
(Preparation of spray solution)
A 0.1 mol / L solution of La _0.68 Ca _0.32 Cr _1.0 O ₃ was prepared in the same manner as in Example 1.

(Spray pyrolysis)
Instead of setting the temperature of the electric furnace to 300 ° C, 500 ° C, 700 ° C, and 900 ° C from the upstream side, respectively, the temperature of the electric furnace is set to 150 ° C, 300 ° C, 500 ° C, and 700 ° C from the upstream side, respectively. A particle C was obtained in the same manner as in Example 1 except that the particle C was set.

(X-ray diffraction analysis)
As a result of X-ray diffraction analysis of the particle C, no diffraction peak indicating the presence of a specific crystal structure was observed in the obtained chart, and a broad and weak diffraction peak characteristic of the amorphous structure was observed. Further, when the particles C were heated in an electric furnace in an air atmosphere at 1000 ° C. or higher for 2 hours and then subjected to X-ray diffraction analysis, the obtained chart showed sharp and strong lanthanum calcium chromite. A diffraction pattern was observed. This indicates that the particles C were oxidized to be particles having a specific crystal structure by being heated in an air atmosphere.

Example 4
(Preparation of spray solution)
A 0.1 mol / L solution of La _0.68 Ca _0.32 Cr _1.0 O ₃ was prepared in the same manner as in Example 1.

(Spray pyrolysis)
Instead of setting the temperature of the electric furnace to 300 ° C, 500 ° C, 700 ° C, and 900 ° C from the upstream side, respectively, the temperature of the electric furnace is set to 150 ° C, 150 ° C, 300 ° C, and 500 ° C from the upstream side, respectively. A particle D was obtained in the same manner as in Example 1 except that the particle D was set.

(X-ray diffraction analysis)
As a result of X-ray diffraction analysis of the particle D, no diffraction peak indicating the presence of a specific crystal structure was observed in the obtained chart, and a broad and weak diffraction peak specific to the amorphous structure was observed. Further, when the particles D were heated in an electric furnace in an air atmosphere at 1000 ° C. or higher for 2 hours and then subjected to X-ray diffraction analysis, the obtained chart showed sharp and strong lanthanum calcium chromite. A diffraction pattern was observed. This indicates that the particles D were oxidized to be particles having a specific crystal structure by being heated in an air atmosphere.

  According to the present invention, a solid oxide fuel cell having a low electrical resistance and having an interconnector that is fired at a low temperature can be manufactured. Therefore, a solid oxide fuel cell having a high output can be manufactured. .

It is typical sectional drawing of the solid oxide fuel cell which has the interconnector of the solid oxide fuel cell of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1a, 1b Fuel electrode 2a, 2b Electrolyte 3a, 3b Air electrode 4a, 4b Solid oxide fuel cell cell 5 Slurry containing powdered metal oxide precursor particles that are amorphous 6 Dry molded body 7 Interconnector 10 Solid oxide fuel cell

Claims (4)

A solid oxide fuel cell comprising powdered metal oxide precursor particles having an average particle diameter of 0.01 to 1 μm obtained by oxidizing a metal or metal salt at 300 to 900 ° C. Base material for interconnectors. The metal oxide precursor particles have the following general formula (1):
_{La (1-x1) A (} x1) Cr (1-y1) Mg (y1) O 3 (1)
(In the formula, A represents Ca or Sr, x1 is 0 to 0.5, and y1 is 0 to 0.15.)
Lanthanum chromite represented by the following general formula (2):
_{D (1-x2) E (} x2) Ti (1-y2) G (y2) O 3 (2)
(In the formula, D represents an alkaline earth metal, Mg, Ca, Sr or Ba, E represents La, Ce, Sm, Pr, Gd, Y or Sc, G represents Nb or Ta, and x2 represents 0. -0.8 and y2 is 0-0.2.)
2. The substrate for an interconnector of a solid oxide fuel cell according to claim 1, wherein the precursor particles are titanate precursor particles represented by the formula: By oxidizing a metal or metal salt at 300 to 900 ° C., powdery metal oxide precursor particles having an average particle diameter of 0.01 to 1 μm are obtained, and then the powdered metal that is amorphous Solid oxide characterized by forming oxide precursor particles and then firing the amorphous powder metal oxide precursor particles to obtain a solid oxide fuel cell interconnector For manufacturing an interconnector of a fuel cell. The firing temperature when firing the amorphous powdered metal oxide precursor particle compact is the firing temperature of the fuel electrode and the air electrode electrically connected by the interconnector of the solid oxide fuel cell. 4. The method for producing an interconnector for a solid oxide fuel cell according to claim 3 , wherein the firing temperature is lower than the higher one.

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