JP6086686B2 - Solid oxide fuel cell and power generation method using the same - Google Patents

Description

  The present invention relates to a solid oxide fuel cell and a power generation method using the same. Specifically, the present invention relates to a solid oxide fuel cell using ammonia as a fuel and a power generation method using the same.

  In a cell for a solid oxide fuel cell (hereinafter sometimes referred to as “SOFC”), oxygen molecules get electrons and become oxygen ions at the air electrode, and these oxygen ions move to the fuel electrode via the solid electrolyte. It reacts with hydrogen and emits electrons. The electrons flow from the fuel electrode to the air electrode via an external circuit, and physical work is performed in this process. The driving force for the operation of the SOFC cell is the difference in oxygen concentration between the air electrode and the fuel electrode. The electromotive force of the SOFC cell is uniquely determined by this oxygen concentration difference and temperature.

  Generally, a nickel-zirconia cermet obtained by mixing nickel oxide and zirconia powder has been used as a fuel electrode material of a solid oxide fuel cell because it has high electrocatalytic activity and high conductivity. (Nickel oxide is reduced by a fuel such as hydrogen to become metallic nickel when operating as a fuel cell. Here, nickel oxide and metallic nickel are referred to as nickel without distinction.) In the cermet, oxidation is performed. The ratio of nickel and zirconia is optimized in consideration of conductivity, coefficient of thermal expansion, electrode reaction activity, and the like. That is, nickel is a substance having electrode activity and electronic conductivity, but if the amount is too large, the ionic conductivity becomes poor and the coefficient of thermal expansion increases. On the other hand, zirconia has ionic conductivity, and maintains the reaction field by fixing nickel powder. However, if the amount is too large, the electronic conductivity is insufficient and densification tends to occur. Therefore, if the mixing ratio of nickel oxide and zirconia is devised, the internal resistance of the fuel cell can be reduced and its performance can be improved.

  On the other hand, a solid oxide fuel cell using ammonia as a fuel has also been proposed. When ammonia is used as the fuel, ammonia is decomposed at the fuel electrode to generate hydrogen and nitrogen, and the oxygen ions are reacted with the generated hydrogen to release electrons. Therefore, when ammonia is used as fuel, it is necessary to efficiently decompose ammonia at the fuel electrode. Therefore, a catalyst using nickel, cobalt, iron or the like as an electrode catalyst for a fuel electrode material and molybdenum, tungsten, iron, ruthenium, cobalt, nickel or the like as an ammonia decomposition catalyst has been proposed (Patent Document 1). .

JP 2011-204416 A

However, in a fuel cell using ammonia as a fuel, in nickel-zirconia cermet generally used as a fuel electrode material, the temperature rise from the room temperature to the operation temperature and the operation temperature to the room temperature associated with the start and stop of the fuel cell are reduced. When exposed to a thermal cycle or at an operating temperature such as 700 to 1000 ° C. for a long time, agglomeration of nickel oxide as an ammonia reforming catalyst component occurs, and the reforming performance of ammonia is lowered, so that the electromotive force is time-consuming. There was a risk of lowering.

  As a result of intensive studies to solve the above problems, the present inventors have obtained a mixture of a nickel compound and zirconia powder after calcining as a fuel electrode material in a fuel cell using ammonia as a fuel. By using nickel oxide-zirconia mixed powder, it has sufficient ammonia decomposition activity as a fuel electrode, has good power generation performance, and suppresses the aggregation of nickel oxide even when exposed to high temperature for a long time, and has high durability The inventors have found that a solid oxide fuel cell exhibiting performance can be obtained, and have completed the present invention. That is, the first invention is a solid oxide fuel cell comprising at least a fuel electrode, an air electrode, and a solid electrolyte, and the fuel electrode material forming the fuel electrode is a mixture of a nickel compound and a first zirconia powder. Of nickel oxide-zirconia mixed powder having an average particle size in the range of 1 to 10 μm and an average particle size in the range of 0.1 to 1 μm obtained by calcination after calcining at a temperature in the range of 500 to 1200 ° C. It is a solid oxide fuel cell that contains second zirconia powder, and in which the nickel compound is at least one selected from the group consisting of nickel oxide, nickel hydroxide, nickel carbonate, and nickel nitrate.

  The second invention is a power generation method in which ammonia is introduced into the fuel electrode of the solid oxide fuel cell and air is introduced into the air electrode.

  By using the fuel electrode material according to the present invention, aggregation of nickel oxide used as an ammonia reforming catalyst component in the fuel electrode formed from the fuel electrode material can be suppressed, and the ammonia reforming reaction efficiency of the fuel electrode is reduced. Can be prevented. As a result, the solid oxide fuel cell using ammonia as the fuel specified by the present invention can continuously obtain a high electromotive force.

  The first invention is a solid oxide fuel cell comprising at least a fuel electrode, an air electrode, and a solid electrolyte, wherein the fuel electrode material forming the fuel electrode is a mixture of a nickel compound and a first zirconia powder. Nickel oxide-zirconia mixed powder having an average particle diameter in the range of 1 to 10 μm obtained by pulverization after calcination at a temperature in the range of ˜1200 ° C. and second in the range of the average particle diameter of 0.1 to 1 μm. A solid oxide fuel cell comprising zirconia powder and using as a fuel ammonia which is at least one selected from the group consisting of nickel oxide, nickel hydroxide, nickel carbonate and nickel nitrate.

(Fuel electrode)
The fuel electrode material used in the present invention has an average particle diameter of 1 to 10 μm obtained by pulverizing a mixture of a nickel compound and first zirconia powder after calcining at a temperature in the range of 500 to 1200 ° C. A nickel-zirconia mixed powder and a second zirconia powder having an average particle size in the range of 0.1 to 1 μm, and the nickel compound is further selected from the group consisting of nickel oxide, nickel hydroxide, nickel carbonate and nickel nitrate. At least one selected is used.

  The fuel electrode material has a ratio of the nickel oxide-zirconia mixed powder in the range of 70 to 95% by mass and a ratio of the second zirconia powder in the range of 5 to 30% by mass. The ratio is preferably nickel oxide. -The ratio of a zirconia mixed powder is in the range of 80 to 90 mass%, and the ratio of the second zirconia powder is in the range of 10 to 20 mass%. When the ratio of the nickel oxide-zirconia mixed powder is less than 70% by mass, the reforming performance of ammonia in the fuel electrode formed from the fuel electrode material is low, and sufficient power generation performance may not be obtained. On the other hand, when the ratio of the second zirconia powder is less than 5% by mass, the adhesive strength with the electrolyte is weakened, and there is a possibility that separation occurs between the electrolyte and the fuel electrode.

  If necessary, an ammonia reforming catalyst component can be further added to the fuel electrode material. Examples thereof include metals and metal compounds such as molybdenum, tungsten, iron, ruthenium, rhodium, and cobalt.

(Nickel oxide-zirconia mixed powder)
The nickel oxide-zirconia mixed powder is a mixed powder having an average particle diameter in the range of 1 to 10 μm obtained by pulverizing a mixture of the nickel compound and the first zirconia powder at a temperature in the range of 500 to 1200 ° C. It is.

The nickel compound is at least one selected from the group consisting of nickel oxide, nickel hydroxide, nickel carbonate and nickel nitrate. The nickel compound can be used in either a solid state or a state dissolved in an aqueous solution, but is preferably a powder. When the nickel compound is a powder, the average particle size is preferably in the range of 0.3 to 5 μm. If it exceeds 5 μm, it may not be sufficiently mixed with the zirconia powder. The specific surface area of the nickel compound powder is preferably in the range of 1.0 to 10 m ² / g because the ammonia reforming performance when the fuel electrode is used becomes high.

  In the present invention, for convenience, zirconia used for the nickel oxide-zirconia mixed powder is distinguished as first zirconia powder, and zirconia powder added as a component of the fuel electrode is distinguished as second zirconia powder.

  The first zirconia powder includes at least one powder selected from the group consisting of 3 to 10 mol% yttria stabilized zirconia, 4 to 12 mol% scandia stabilized zirconia, and 3 to 15 mol% ytterbia stabilized zirconia. It can be suitably used because of its excellent ionic conductivity.

The average particle size of the first zirconia powder is preferably in the range of 0.1 to 1 μm because it can be quickly mixed with the nickel compound. Further, the specific surface area of the first zirconia powder is preferably within a range of 3.0 to 30 m ² / g because aggregation of nickel oxide when the fuel electrode is used can be further suppressed.

  In the nickel oxide-zirconia mixed powder, the mixing ratio of both components may be adjusted as appropriate, but preferably the ratio of nickel oxide and zirconia is within the range of 40/60 to 70/30 as the mass ratio of nickel oxide / zirconia. is there. When the ratio is less than 40/60 by mass ratio of nickel oxide / zirconia, the resulting fuel electrode has insufficient ammonia reforming activity and insufficient electronic conductivity, which may result in insufficient power generation performance. On the other hand, when the ratio exceeds 70/30, the ionic conductivity of the obtained fuel electrode is insufficient, and the suppression of the aggregation of nickel oxide becomes insufficient, and the durability may be lowered. The mixing ratio of both components is more preferably in the range of 50/50 to 65/35 in terms of mass ratio of nickel oxide / zirconia.

  The average crystallite diameter of nickel oxide in the nickel oxide-zirconia mixed powder of the present invention is preferably in the range of 1 to 100 nm. If the average crystallite diameter of nickel oxide is within this range, the fuel electrode using the mixed powder can have both high ammonia reforming activity and electronic conductivity. The average crystallite diameter is more preferably in the range of 1 to 50 nm, and most preferably in the range of 1 to 20 nm. In addition, the average crystallite diameter of nickel oxide in the present invention is the value of the (111) plane and the (200) plane of NiO in which the respective crystallite diameters are calculated from the values measured by the X-ray diffraction method using the Scherrer equation. Mean value.

(Preparation of nickel oxide-zirconia mixed powder)
To prepare the nickel oxide-zirconia mixed powder, first, the nickel compound and the first zirconia powder are mixed. As a means for mixing the nickel compound and the first zirconia powder, it may be simply dispersed and mixed in a solvent such as water, but it is preferable to use a wet ball mill because a uniform mixture can be obtained. It can also be performed by mixing by a mechanical pulverization method using a rough machine. The obtained mixture is calcined at a temperature in the range of 500 to 1200 ° C. If it is less than 500 degreeC, decomposition | disassembly of the said nickel compound will become inadequate and there exists a possibility that the movement of the nickel component may occur at the time of mixing nickel oxide-zirconia mixed powder and second zirconia powder. On the other hand, by setting the calcining temperature to 1200 ° C. or less, excessive sintering can be suppressed, and the crystallite diameter of nickel oxide in the obtained nickel oxide-zirconia mixed powder can be within a predetermined range, The active sites necessary for the ammonia decomposition reaction can be sufficiently maintained. Moreover, adhesiveness with an electrolyte can also be maintained.

  The calcining temperature is preferably in the range of 600 to 1200 ° C, more preferably in the range of 700 to 1100 ° C.

  Subsequently, the obtained calcined product is pulverized to obtain a nickel oxide-zirconia mixed powder having an average particle size of 1 to 10 μm. The average particle size is preferably in the range of 1-8 μm. If the average particle size is less than 1 μm, nickel oxide may be aggregated during operation of the fuel cell at high temperatures, and if it exceeds 10 μm, the handleability of the fuel electrode paste of the present invention may be deteriorated. By simply calcination, the particle diameter ranges from several μm to several hundred μm, so the average particle diameter is adjusted by grinding. There is no particular limitation on the pulverizing means, and a conventional method can be used, but it is preferable to use a planetary ball mill.

  The above mixture usually has particle size peaks in the vicinity of 1 μm and several tens of μm, and the ratio of the two particle size peaks changes as the pulverization proceeds, and the average particle size (50% by volume) decreases. Therefore, at the time of pulverization, an appropriate sample may be taken to measure the average particle diameter, and the pulverization operation may be stopped when the desired average particle diameter is reached.

(Second zirconia powder)
As the second zirconia powder in the present invention, the same as the first zirconia powder can be used. For example, at least one powder selected from the group consisting of 3 to 10 mol% yttria stabilized zirconia, 4 to 12 mol% scandia stabilized zirconia, and 3 to 15 mol% ytterbia stabilized zirconia, and having a particle size of The thing of 0.1-1 micrometer and a specific surface area of about 3.0-30 m < ² > / g can be used conveniently. The particle diameter is preferably in the range of 0.1 to 0.8 μm. If the particle diameter is less than 0.1 μm, the handleability of the fuel electrode paste of the present invention may be lowered, and if it exceeds 1 μm, the adhesion between the fuel electrode and the solid electrolyte may be lowered.

(Measurement of particle diameter)
The average particle diameter (50 volume% diameter) of the powder in the present invention is 0.2 mass% metaphosphoric acid as a dispersant in distilled water using, for example, a laser diffraction particle size distribution analyzer “LA-920” manufactured by Horiba, Ltd. This is a measured value after using an aqueous solution to which sodium has been added as a dispersion medium, adding 0.01 to 0.5% by mass of each particle in about 100 cm 3 of the dispersion medium, and dispersing by sonication for 3 minutes. The 50 volume% diameter is the particle diameter at 50 volume% in the cumulative graph in the measurement result of the particle size distribution.

(Solid oxide fuel cell)
The solid oxide fuel cell according to the present invention is composed of at least a fuel electrode, an air electrode, and a solid electrolyte, with a fuel electrode disposed on one surface of the solid electrolyte and an air electrode disposed on the other surface.

  The nickel oxide-zirconia mixed powder in the present invention is reduced to nickel metal in the fuel electrode under a cell operating atmosphere to form metallic nickel, and forms a reaction field for decomposition reaction and electrode reaction of ammonia used as fuel. The mixed powder is thermally stable by calcination and imparts durability to the fuel electrode. In addition, since the mixed powder has a relatively high density, it exhibits high conductivity and also has excellent gas diffusibility because there are voids between the particles.

  The second zirconia powder in the present invention improves the adhesion between the nickel compound-zirconia mixed powders and between the solid electrolyte and the fuel electrode, and imparts high ionic conductivity to the fuel electrode. In addition, aggregation of nickel can be suppressed and a three-phase interface with the mixed powder can be maintained. Therefore, in the fuel electrode in the present invention, the ammonia decomposition activity is superior to that of the conventional one, the electrode reaction field is large, and the aggregation of the nickel oxide powders and the change in the porosity are suppressed. As a result, the solid oxide fuel cell according to the present invention has excellent initial power generation performance when ammonia is used as fuel, and has excellent characteristics that the fuel electrode is hardly deteriorated even if power is generated for a long time. In the present invention, all nickel components in the fuel electrode are indicated as nickel oxide, but it goes without saying that the nickel oxide is reduced to metal nickel in the fuel electrode during actual fuel cell operation. No. Below, the manufacturing method is demonstrated with description of each part.

(Fuel electrode manufacturing method)
In step 1, a nickel oxide-zirconia mixed powder and a second zirconia powder are mixed. As a mixing method, a conventional method may be used. For example, the same means as the mixing means of the nickel compound and the first zirconia powder can be used.

  In step 2, the mixed material is made into a paste. Specifically, the fuel electrode material of the present invention is made of a binder such as ethyl cellulose, polyethylene glycol or polyvinyl butyral resin; a solvent such as ethanol, toluene, α-terpineol or carbitol; a plasticizer such as glycerin, glycol or dibutyl phthalate. Further, a paste having an appropriate viscosity is obtained by using, for example, a ball mill, a three-roll mill or a planetary mill together with a dispersing agent, an antifoaming agent, a surfactant and the like which are blended as necessary.

  When the fuel electrode is formed by coating or dipping, the viscosity of the paste is adjusted to 1 to 50 mPa · s, more preferably 2 to 20 mPa · s with a B-type viscometer. A preferable viscosity when the fuel electrode is formed by screen printing is 50,000 to 2,000,000 mPa · s, more preferably 80,000 to 1,000,000 mPa · s, more preferably 100 by Brookfield viscometer. , 000 to 500,000 mPa · s. The fuel electrode paste is coated on a solid electrolyte by a bar coater, a spin coater, a dipping device or the like, or formed into a thin film by a screen printing method or the like, and then a temperature of 40 to 150 ° C., for example, 50 ° C., 80 C. and 120.degree. C., or successively heated up and dried successively. Next, it is preferably fired at 1200 to 1300 ° C. to form a fuel electrode. At this time, if the temperature is 1200 ° C. or higher, the sintering proceeds sufficiently and sufficient electrical conductivity is obtained. On the other hand, by setting the sintering temperature to 1300 ° C. or lower, it is possible to sufficiently suppress a decrease in ammonia decomposition activity and electrode reaction activity due to excessive sintering.

  In the case of an electrolyte self-supporting membrane cell, the thickness of the fuel electrode layer is suitably about 10 to 300 μm, preferably 15 to 100 μm, more preferably 20 to 50 μm. In the case of a fuel electrode supporting membrane type cell, 0.3 to 3 mm is suitable, more preferably 0.5 to 2.5 mm, and particularly preferably 1 to 2 mm.

(Solid electrolyte)
A known solid electrolyte may be used. For example, what consists of various stabilized zirconia with high oxygen ion conductivity can be used on the conditions which use the solid oxide fuel cell which concerns on this invention. More specifically, 3 to 15 mol% of yttria, scandia, ceria, or zirconia stabilized by adding two or more thereof is used. Among them, those made of stabilized zirconia containing 4 mol% or more of scandia are preferable because of high ionic conductivity and excellent mechanical properties.

  The thickness of the solid electrolyte can be appropriately adjusted according to the required electrical conductivity and strength. For example, the supporting substrate made of stabilized zirconia containing 4 to 6 mol% scandia is preferably 100 μm or less. In the stabilized zirconia containing 10 mol% or more of scandia, the thickness is preferably 500 μm or less, more preferably 300 μm or less.

(Air electrode)
As the air electrode, one made of a perovskite oxide that has both electronic conductivity and ionic conductivity and is stable even in an oxidizing atmosphere is generally used. _{Specifically, La 0.8 Sr 0.2 MnO 3,} La 0.6 Sr 0.4 Co 0.2 FeO 3, La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3 , etc. As the air electrode material, lanthanum manganite in which a part of lanthanum is substituted with strontium, lanthanum ferrite or lanthanum cobaltite in which a part of lanthanum is substituted with strontium is preferable. In addition, in order to increase the oxygen ion conductivity of the air electrode, ceria doped with rare earth or the like can be appropriately mixed.

  The air electrode material can be used to form an air electrode on a solid electrolyte after being made into an air electrode paste in the same manner as the fuel electrode material described above. At this time, a reaction preventing layer may be provided in order to prevent the generation of an insulating material between the electrolyte and the air electrode. Such a reaction preventing layer is generally formed of rare earth doped ceria. The reaction preventing layer and the air electrode may be fired individually, or may be fired simultaneously with the fuel electrode.

(Power generation method)
The second invention is a power generation method characterized by introducing ammonia into the fuel electrode of the solid oxide fuel cell according to the present invention and introducing air into the air electrode.

  The fuel introduced into the fuel electrode is ammonia, and the concentration of ammonia may be 100% by volume, but it can also be used by mixing with a gas inert to the reaction of the fuel electrode or with hydrogen. The inert gas that can be mixed includes nitrogen, argon, and helium, and the mixing amount is not particularly limited, but is preferably in the range of 1 to 50% by volume with respect to the gas introduced into the fuel electrode. Further, the mixing amount when hydrogen is mixed is not particularly limited, but is preferably in the range of 1 to 90% by volume, more preferably in the range of 5 to 50% by volume with respect to the gas introduced into the fuel electrode. .

  Any gas can be used as long as it contains oxygen and gas introduced into the air electrode. Oxygen and air can be used. However, if the gas is inert to the reaction of the air electrode, it can be mixed with oxygen or the like. It can also be used.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited by the following examples, but may be appropriately modified within a range that can meet the purpose described above and below. It is also possible to implement, and they are all included in the technical scope of the present invention. Hereinafter, “stabilized zirconia” is simply referred to as “SZ”. For X-ray diffraction measurement, an X-ray diffractometer (product name “X′Pert Pro MPD”, manufactured by Spectris Co., Ltd.) was used. CuKα (0.154 nm) was used as the X-ray source, and the measurement conditions were an X-ray output of 45 kV, 40 mA, a step size of 0.017 °, a scan step time of 100 seconds, and a measurement temperature of 25 ° C.

Example 1
(1) Production of nickel oxide-zirconia mixed powder 125 parts by mass of nickel oxide powder (manufactured by Shodo Chemical Co., Ltd., product name: Green, average particle size: 0.7 μm), 10 mol% scandia 1 mol% ceria stabilized zirconia powder (Hereafter, abbreviated as 10Sc1CeSZ powder.) (Made by 1st rare element, average particle size: 0.63 μm) 65 parts by mass are put in a 1 L magnetic pot and 5 mmφ zirconia balls and 10 mmφ zirconia balls are used as media, and 50% ethanol. Wet mixing was performed for 24 hours at 60 rpm with the aqueous solution as a solvent. The obtained mixed powder was dried and calcined at 1100 ° C. Next, 100 parts by mass of the calcined mixed powder was put in a 250 mL alumina pot, and 6 20 mmφ zirconia balls were used as media to dry-grind with a planetary mill for 10 minutes at 240 rpm, and the mass ratio of nickel oxide / zirconia A 66/34 nickel oxide-zirconia mixed powder was obtained.

  The particle size distribution and average particle size of the obtained nickel oxide-zirconia mixed powder were measured with a laser diffraction particle size distribution measuring device (product name: LA-920, manufactured by Horiba, Ltd.). As a dispersion medium, 0.2 mass% sodium metaphosphate aqueous solution was used, and ultrasonic irradiation was performed for 3 minutes before the measurement. As a result, the average particle size was 7.0 μm. Furthermore, the crystallite diameter of nickel oxide in the nickel oxide-zirconia mixed powder measured by the X-ray diffraction method was 25 nm.

(2) Production of Fuel Electrode Material and Fuel Electrode Paste 90% by mass of the nickel oxide-zirconia mixed powder and 10% by mass of 10Sc1CeSZ powder (manufactured by 1st rare element, average particle size: 0.63 μm) are mixed to obtain 5 mmφ zirconia. Wet mixing was performed for 24 hours at 60 rpm with a ball and 10 mmφ zirconia ball as media and 50% ethanol aqueous solution as a solvent. This was dried to obtain a fuel electrode material. To 100 parts by mass of the fuel electrode material, 3 parts by mass of ethyl cellulose as a binder and 40 parts by mass of α-terpineol as a solvent were added and kneaded using a roll mill to obtain a fuel electrode paste.

(3) Production of air electrode paste La _0.6 Sr _0.4 Co _0.2 Fe _0.8 O ₃ (manufactured by Seimi Chemical, average particle size: 0.5 μm), 3% by weight of ethyl cellulose as a binder, solvent As a fuel electrode paste, α-terpineol was added at a rate of 30% by mass and kneaded using a roll mill.

(4) Preparation of reaction prevention layer paste 20 mol% Gadria-doped ceria (manufactured by Seimi Chemical, average particle size: 0.5 μm) is added to glycerin containing 10% water and kneaded using a roll mill to prevent reaction. A layer paste was used.

(5) Manufacture of electrolyte support membrane type cell The above fuel electrode paste was applied in a 10 mmφ circle shape by screen printing on one side of a 6 mol% scandia stabilized zirconia sheet (30 mmφ × 100 μm thickness). And dried at 90 ° C. for 5 hours. Next, on the opposite side, the reaction preventing layer paste was applied in the shape of a circle of 10 mmφ by screen printing and dried in the same manner. This was sintered at 1300 ° C. for 5 hours. Subsequently, the air electrode paste is screen-printed in the shape of a circle of 10 mmφ on the reaction preventing layer, dried at 90 ° C. for 5 hours, and then sintered at 1000 ° C. for 3 hours. A mold cell was obtained. The film thicknesses of the fuel electrode, air electrode, and reaction preventing layer were about 40 μm, 30 μm, and 10 μm, respectively.

(Example 2)
(1) Manufacture of nickel oxide-zirconia mixed powder 196 parts by mass of basic nickel carbonate (manufactured by Wako Pure Chemical Industries) and 100 parts by mass of 10Sc1CeSZ powder (manufactured by Daiichi Rare Elements, average particle size: 0.63 μm) The mixture was placed in a pot and wet-mixed for 24 hours at 60 rpm with a 5 mmφ zirconia ball and a 10 mmφ zirconia ball as media and a 50% ethanol aqueous solution as a solvent. The obtained mixed powder was dried and calcined at 600 ° C. Next, in the same manner as in Example 1, a nickel oxide-zirconia mixed powder having a nickel oxide / zirconia mass ratio of 50/50 was obtained.

  The particle size distribution and average particle size of the obtained mixed particles were measured in the same manner as in Example 1, and the average particle size was 6.5 μm. Further, the crystallite diameter of nickel oxide in the mixed powder measured by the X-ray diffraction method was 18 nm.

(2) Manufacture of fuel electrode material and fuel electrode paste The nickel oxide-zirconia mixed powder was mixed with 95% by mass and 5% by mass of 10Sc1CeSZ powder (manufactured by 1st rare element, average particle size: 0.63 μm). In the same manner as in Example 1, a fuel electrode material was obtained. Further, a fuel electrode paste was prepared in the same manner as in Example 1.

(3) Manufacture of electrolyte support membrane type cell An electrolyte support membrane type cell for a fuel cell was obtained in the same manner as in Example 1 except that the fuel electrode paste was used.

(Comparative Example 1)
(1) Production of Comparative Nickel Oxide-Zirconia Mixed Powder 196 parts by mass of basic nickel carbonate (manufactured by Wako Pure Chemical Industries) and 100 parts by mass of 10Sc1CeSZ powder (manufactured by Daiichi Rare Elements, average particle size: 0.63 μm) In the same manner as in Example 2, a mixed powder was obtained and calcined at 1400 ° C. Next, in the same manner as in Examples, a comparative nickel oxide-zirconia mixed powder having a mass ratio of nickel oxide / zirconia of 50/50 was obtained.

  The particle size distribution and average particle size of the obtained mixed particles were measured in the same manner as in Example 1, and the average particle size was 17.5 μm. Further, the crystallite diameter of nickel oxide in the mixed powder measured by the X-ray diffraction method was 110 nm.

(2) Manufacture of fuel electrode material and fuel electrode paste The nickel oxide-zirconia mixed powder was mixed with 95% by mass and 5% by mass of 10Sc1CeSZ powder (manufactured by 1st rare element, average particle size: 0.63 μm). In the same manner as in Example 1, a comparative fuel electrode material was obtained. Further, a comparative fuel electrode paste was prepared in the same manner as in Example 1.

(3) Manufacture of electrolyte support membrane type cell An electrolyte support membrane type cell for a comparative fuel cell was obtained in the same manner as in Example 1 except that the fuel electrode paste was used.

(Comparative Example 2)
(1) Production of Comparative Fuel Electrode Material and Fuel Electrode Paste Nickel oxide powder (manufactured by Shodo Chemical, product name: Green, average particle size: 0.7 μm) 50% by mass and 10Sc1CeSZ powder (manufactured by 1st rare element, average) (Particle size: 0.63 μm) 50% by mass was mixed, and a comparative fuel electrode material was obtained in the same manner as in Example 1. Further, a comparative fuel electrode paste was prepared in the same manner as in Example 1.

(2) Manufacture of electrolyte support membrane type cell An electrolyte support membrane type cell for a comparative fuel cell was obtained in the same manner as in Example 1 except that the fuel electrode paste was used.

(Test Example 1)
For the electrolyte support membrane cells of Examples 1 and 2 and Comparative Examples 1 and 2, a power generation test was performed using a small single cell power generation test apparatus, and the output density was measured. Ammonia (flow rate 0.167 L / min) was used as the fuel electrode side gas, air (flow rate 0.250 L / min) was used as the air electrode side gas, and the test temperature was 800 ° C. In the measurement, a model number “TR6845” manufactured by Advantest Corporation was used as a current measuring instrument, and a model number “GP016-20R” manufactured by Takasago Seisakusho Co., Ltd. was used as a current voltage generator. The maximum power density (W / cm ² ) at the start of the power generation test and after 400 hours was determined. The results are shown in Table 1.

  In Examples 1 and 2 which are solid oxide fuel cells according to the present invention, a nickel oxide-zirconia mixture obtained by pulverizing a mixture of a nickel compound and zirconia powder as a fuel electrode material after calcining at a predetermined temperature By using the powder, it has sufficient ammonia decomposition activity as a fuel electrode, has good power generation performance, and suppresses the aggregation of nickel oxide even when exposed to high temperatures for a long time, and has excellent durability. It was. On the other hand, in Comparative Example 1, since calcining was performed at a temperature higher than a predetermined temperature during the production of the nickel oxide-zirconia mixed powder, the nickel oxide agglomerates, and the fuel electrode using the mixed powder has ammonia decomposition activity. The solid oxide fuel cell having the fuel electrode had poor power generation characteristics. Further, in Comparative Example 2, since the nickel oxide powder is used as it is, the initial ammonia decomposition activity as the fuel electrode is excellent, but the stability of nickel oxide in the fuel electrode is poor, so the solid having the fuel electrode The durability of the oxide fuel cell was poor.

  In the present invention, ammonia can be used as a fuel in a solid oxide fuel cell, and further, electric power can be generated using this cell.

Claims (3)

A solid oxide fuel cell comprising at least a fuel electrode, an air electrode and a solid electrolyte, wherein the fuel electrode material is a mixture of a nickel compound and a first zirconia powder in the range of 500 to 1100 ° C. A nickel oxide-zirconia mixed powder having an average particle size in the range of 1 to 10 μm and a second zirconia powder having an average particle size in the range of 0.1 to 1 μm, obtained by pulverizing after calcination at an internal temperature, In the nickel oxide-zirconia mixed powder, the ratio of nickel oxide to zirconia is in the range of 40/60 to 70/30 by mass ratio of nickel oxide / zirconia, and the average crystallite diameter of nickel oxide in the mixed powder is in the range of 1 to 100 nm, selected from the group the nickel compound is nickel oxide, nickel hydroxide, nickel carbonate and nickel nitrate Solid oxide fuel cell using ammonia, characterized in that at least one the fuel. 2. The ammonia according to claim 1 , wherein in the fuel electrode material, the ratio of the nickel oxide-zirconia mixed powder is in the range of 70 to 95 mass% and the ratio of the second zirconia powder is in the range of 5 to 30 mass%. Solid oxide fuel cell. A power generation method, wherein ammonia is introduced into the fuel electrode of the solid oxide fuel cell according to claim 1 or 2 , and air is introduced into the air electrode.