KR20120089939A - A method for preparing nio/ysz composite for a solid oxide fuel cell - Google Patents

Abstract

PURPOSE: A manufacturing method of a NiO/YSZ composite for solid oxide fuel cell is provided to obtain uniform nano-sized NiO/YSZ composite through co-precipitation and hydrothermal synthesis by adding NaOH solution precursor-mixed solution of high pH. CONSTITUTION: A manufacturing method of a NiO/YSZ composite for solid oxide fuel cell comprises: a step of adding precursor mixed solution of nickel precursor, ytrrium precursor, and zirconium precursor into basic solution; a step of forming mixed precipitate of nickel hydroxide, yttrium hydroxide, and zirconium hydroxide by controlling pH to 11 or more; and a step of heat treating the mixed precipitate to 80-180 °C. The basic solution is one selected from a group consisting of NaOH, KOH, NH3, (NH3)HCO3, and (NH3)2CO3.

Description

A method for preparing NiO / YSZ Composite for a Solid Oxide Fuel Cell}

The present invention relates to a composite material manufacturing method of the solid oxide fuel cells and nickel oxide, a yttria-stabilized zirconia _{(Yttria Stabilized ZrO 2 (YSZ)} , NiO / YSZ). More specifically, the present invention relates to a method for producing a Ni / YSZ composite for a solid oxide fuel cell by co-precipitation and hydrothermal synthesis.

A fuel cell is a device that generates electricity by reacting fuel such as hydrogen or natural gas with oxygen and is recognized as one of the main energy technologies of the future because of its high efficiency, pollution-free, and noise-free characteristics.

Fuel cell types include molten carbonate fuel cells (MCFC), solid oxide fuel cells (SOFC), and phosphoric acid fuel cells (AFC), polymer electrolyte fuel cells (PEMFC), and direct methanol that operate at relatively low temperatures. Fuel cell (DEMFC);

Dual solid oxide fuel cells (SOFCs) are energy conversion devices that produce direct current electricity by electrochemically reacting oxidants (eg oxygen) and gaseous fuels (eg hydrogen) through an oxide electrolyte. to be.

Key features of current solid oxide fuel cell techniques include solid-state structure, adaptability of multiple fuels, and high temperature operability. Due to the characteristics of such a solid oxide fuel cell, a solid oxide fuel cell has the potential to be a high performance, clean and efficient power source, has been developed for various power generation applications.

A solid oxide fuel cell is formed by stacking unit cells, which are ceramic multilayer structures composed of an oxide electrolyte interposed between a cathode (anode) and an anode (cathode), in series. A unit cell of a conventional solid oxide fuel cell is not limited thereto, for example, Yttria Stabilized ZrO ₂ (YSZ) as an electrolyte, and strontium doped lanthanum manganite (LaSrMnO ₃ ) as an anode. And a composite of nickel oxide (NiO) and yttria stabilized zirconia (NiO / YSZ) as the cathode.

The negative electrode is a very important component that must satisfy the electrochemical properties as well as the physical properties required in terms of structure. The negative electrode requires features such as mechanical strength, electrical conductivity, gas permeability, electrochemical activity, and the like. Specifically, the negative electrode material used in the anode-supported solid oxide fuel cell is not only mechanical strength for supporting the unit cell structure, but also a fuel gas, and has a high porosity and a gas so that hydrogen or natural gas can be sufficiently penetrated and reacted. Permeability is required.

However, the anode material for the solid oxide fuel cell (SOFC) has a problem that the activity of the gas reaction is low due to the coarse anode material particles. Specifically, the coarse anode material particles do not sufficiently form a triple phase boundary (TPB) in which a gas reaction occurs inside the resulting negative electrode material. In order to overcome this problem, a fine NiO / YSZ composite powder structure may be formed between the negative electrode support and the electrolyte to improve reactivity. Hydrothermal synthesis has been applied in various ways as a way to form a nano-sized ceramic powder. However, since NiO and YSZ, which are precursors of NiO and zirconia, which are precursors of YSZ, and yttria, which exist as stable phases, are very different in concentration and pH, they are difficult to produce NiO and YSZ in uniform powders at the same time. Precipitants most widely used for hydrothermal synthesis include ammonia, ammonia carbonate, and ammonia bicarbonate, but it is difficult to prepare NiO / YSZ because it is difficult to control pH by controlling equilibrium with the produced ammonium ions.

Accordingly, in order to manufacture the NiO / YSZ composite by the hydrothermal synthesis method, nickel oxide (NiO) and YSZ are separately prepared, sintered, and a negative electrode material powder for fuel cells has been prepared by mixing them. Therefore, since the prior art requires a four-step process and a mixing process including two sintering processes of NiO manufacturing process, NiO sintering process, YSZ manufacturing process, and YSZ sintering process in order to prepare NiO / YSZ mixture, a total of 5 Assembly manufacturing process is required. In particular, the sintering process is a factor that greatly affects the manufacturing cost of the ceramic powder, and the conventional method has a problem in that the production cost increases due to two sintering processes.

According to one embodiment of the present invention there is provided a method for producing a nano-sized NiO / YSZ composite in a single process.

According to one embodiment of the present invention, adding a precursor mixed solution of a nickel precursor, a yttrium precursor and a zirconium precursor to a basic solution and adjusting the pH to about 11 or more to form a mixed precipitate of nickel hydroxide, yttrium hydroxide and zirconium hydroxide; And

The NiO / YSZ composite manufacturing method comprising the step of heat-treating the mixed precipitate to 80 to 180 ℃ is provided.

According to the method according to the embodiment of the present invention, NiO / YSZ composites are manufactured in a single process without having to separately prepare NiO and YSZ. By coprecipitation and hydrothermal synthesis, which is achieved by adding a precursor mixture solution to a basic solution of high pH, a uniform nano-sized NiO / YSZ composite is obtained in high yield. The NiO / YSZ composite prepared by the method according to the embodiment of the present invention is coated with (doped) NiO on the surface of the YSZ particles, thereby increasing the triple phase boundary (TPB) in which gas reaction inside the negative electrode material occurs. . In addition, the NiO / YSZ composite is an increase in surface area as a nano-sized powder. The increase in the surface area also increases the three-phase junction (TPB) where the gas reaction inside the anode material occurs and the contact area between the electrolyte and the cathode is increased, thereby reducing the interfacial resistance between the electrolyte and the cathode and outputting the solid oxide fuel cell. Performance is improved. In the preparation of the complex, the basic solutions used, in particular the sodium or potassium impurities of sodium hydroxide and potassium hydroxide, have the advantage of increasing performance by increasing oxygen ion sites between the particles of YSZ, thus removing No precise cleaning process is required.

1 is a SEM photograph (magnification 50000 x) of a NiO / YSZ composite obtained by the method according to the present invention in Example 1. FIG.
FIG. 2 is a SEM photograph (magnification 50000 ×) of the NiO / YSZ composite obtained by the present invention in Example 2. FIG.
3 is a graph showing the performance of a fuel cell using Example 1 and a conventional NiO / YSZ composite powder.

According to one embodiment of the present invention, nickel hydroxide, yttrium hydroxide and zirconium hydroxide are co-precipitated by adding a precursor mixture solution of a nickel precursor, a yttrium precursor and a zirconium precursor to a high pH basic solution and adjusting the pH to a high pH of 11 or higher. A uniform nano-sized NiO / YSZ composite is prepared in a single process by heat-treating the mixed precipitate of nickel coprecipitate, yttrium hydroxide, and zirconium hydroxide (hereinafter referred to as 'mixed precipitate') by hydrothermal synthesis (Hydor Thermal Synthesis). .

To the basic solution, a precursor mixture solution of nickel precursor, yttrium precursor and zirconium precursor (hereinafter referred to as 'precursor mixture solution') is added and the pH is at least 11, preferably at least 12, more preferably at least pH 13, and most Preferably it is adjusted to pH 13-13.7. By allowing the pH to be within the pH range, small and uniform sized precipitates are obtained in a uniformly dispersed state. In addition, most, preferably at least 95%, more preferably 100% (by weight) of precipitates form a precipitate. As the basic solution, at least one selected from the group consisting of NaOH, KOH, NH ₃ , (NH ₃ ) HCO ₃ and (NH ₃ ) ₂ CO ₃ may be used alone or in combination. As the basic solution, preferably NaOH, KOH, and / or NH ₃ , more preferably NaOH, and / or KOH, most preferably NaOH can be used.

The basic solution is preferably used at a concentration of 0.05M to 0.5M. This is because nickel hydroxide, yttrium hydroxide and zirconium hydroxide precipitate in a fine and evenly dispersed state and in a high yield without aggregation of particles in the concentration range. Specifically, when the concentration of the basic solution is less than 0.05M may be long settling time, the reaction yield may be insufficient, and when the concentration of the basic solution exceeds 0.5M, the aggregation between particles may proceed rapidly due to rapid precipitation.

There is an isoelectric pH, depending on the material, and about 10 to 11 for nickel hydroxide. In the case where nickel hydroxide is produced in the pH range, the precipitate does not charge, so that the particles aggregate to form coarse particles. Therefore, when the basic solution is added to the precursor mixed solution, the pH is increased by adding the basic solution, and thus the isoelectric point pH range of the nickel is passed. As a result, the particles aggregate to form coarse particles, as well as precipitates. This is not preferable because it is not well dispersed.

Therefore, in the method according to one embodiment of the present invention, the precursor mixture solution should be added to the basic solution of high pH so as not to be in the isoelectric point pH range when forming the mixed precipitate, and after addition, the pH is 11 or more, preferably 12 Or more, more preferably pH 13 or more, and most preferably pH 13 to 13.7. The pH adjustment can be adjusted by adding NaOH and / or KOH solution. That is, if the pH is less than 11 particles are aggregated or entangled to become coarse, so the pH is preferably 11 or more. As such, by adding the precursor mixture solution to the basic solution of high pH and adjusting the pH to 11 or more thereafter, the precipitate is not entangled and thus fine particles are evenly dispersed. In addition, most of the reactants may be precipitated, preferably at least 95%, more preferably 100% (by weight).

Furthermore, it is preferable to use the basic solution of the said concentration in the amount which will be 1 equivalent or more with respect to content of the metal anion in precursor solution. The precipitate is formed by the reaction of the hydroxyl group (or ammonia) in the basic solution with the cation of the precursor solution, where the hydroxyl group (or ammonia) and the cation react in a 1: 1 equivalent amount, so that the basic solution contains the amount of the metal anion in the precursor solution. It is preferably used in an amount such that the amount thereof is 1 equivalent or more, preferably 1 to 3 equivalents. The use of the basic solution in this amount is preferred because not only the reactant is completely precipitated, but the precipitate is obtained in a state of being evenly dispersed in fine powder without clumping.

The precursor mixed solution may be prepared by dissolving each precursor in distilled water. As precursors of nickel, yttrium and zirconium, any precursor generally known in the art may be used. Examples thereof are not limited thereto, but the following may be mentioned. Nickel nitrate and / or nickel chloride may be used as the nickel precursor. Yttrium oxychloride, yttrium chloride, and / or yttrium nitrate may be used as the yttrium precursor. Zirconium oxychloride, zirconium chloride, and / or zirconium nitrate may be used as the zirconium precursor. The content of each metal precursor in the precursor mixture solution can be appropriately adjusted according to the content of nickel oxide, yttrium and zirconium intended in the final composite. For example, but not limited to, when preparing the precursor mixture solution, the nickel precursor may be dissolved in distilled water such that the concentration of nickel cation is 0.01 M to 1.0M. The yttrium precursor may be dissolved in distilled water such that the concentration of the yttrium cation is 0.001M to 0.1M. The zirconium precursor may be dissolved in distilled water such that the concentration of zirconium cations is 0.05M to 1.0M.

In detail, it is preferable that the nickel precursor be dissolved in the above range for reasons of extremely small loss and optimum weight ratio. The yttrium precursor is preferably dissolved in the above range to optimize the doping amount. It is preferable to dissolve the zirconium precursor in the above range for reasons of the optimum electrochemical performance considering the weight ratio with nickel oxide. The coprecipitation is performed at room temperature.

Furthermore, it is more preferable to add and stir the precursor mixed solution to the basic solution so that a precipitate is obtained in a more uniformly dispersed fine phase. Preferably, stirring at 100 rpm or more is good in terms of achieving the intended stirring effect. The upper limit of the stirring speed is not particularly limited, and a person skilled in the art may suitably adjust according to the state of the reactants.

The precipitate is sufficiently precipitated by reacting the reaction for up to 30 minutes, preferably 5 to 30 minutes. Precipitation occurs almost immediately, and after 30 minutes of reaction, it is sufficiently precipitated.

The mixed precipitate of the co-precipitated nickel hydroxide, yttrium hydroxide and zirconium hydroxide is directly added to a hydrothermal synthesizer, followed by heat treatment to directly obtain a NiO / YSZ composite. In the method according to the present invention, the NiO / YSZ composite may be prepared by directly heat treating the basic solution and the precipitate together without having to recover the precipitate from the basic solution. In addition, if necessary, all or part of the basic solution may be removed and the precipitate may be heat treated. In the method according to the embodiment of the present invention, most of the precursor, preferably 95% or more, more preferably 100% (by weight) is precipitated, so there is no unreacted material, so all of the reactants are not required to be recovered separately. The composite may be prepared by hydrothermal synthesis as it is.

The heat treatment is performed at a temperature of 80 ° C to 180 ° C in consideration of the production efficiency and fairness of the NiO / YSZ composite. Specifically, if the heat treatment temperature is less than 80 ℃, the hydrothermal reaction rate is very slow, the precipitation yield is low, if the temperature exceeds 180 ℃ high temperature and high pressure is formed inside the reactor, the reactor life is shortened and the reactor life is difficult and mass production is difficult It is not preferable at the point which manufacture cost increases rapidly.

The heat treatment is preferably performed for 24 to 99 hours in terms of yield of the NiO / YSZ composite. If the heat treatment time is less than 24 hours, it is not preferable in that a yield of 95% or more is difficult, and even if the heat treatment time exceeds 99 hours, the yield is no longer increased. Therefore, it is preferable to perform the said reaction time and reaction temperature in the said optimum range in consideration of the relationship between a yield and process input cost.

By heat treatment as described above, yttria and zirconium hydroxide are dehydrated and condensed with each other and / or with each other to form Yttria Stabilized ZrO ₂ (YSZ). On the other hand, nickel hydroxide by hydrothermal synthesis also becomes nickel oxide by dehydration condensation reaction, and the nickel oxide is coated (doped) on the surface of the YSZ to form a NiO / YSZ composite. Thereafter, the obtained composite is washed and dried to remove Na ⁺ ions dissolved in the solution. Washing and drying can be carried out by general methods known in the art and are not limited thereto.

The obtained NiO / YSZ composite has a particle size of about 20 nm to 100 nm and a surface area of about 5 m 2 / g to 150 m 2 / g.

According to the method according to the embodiment of the present invention, NiO / YSZ composites are manufactured in a single process without having to separately prepare NiO and YSZ. By coprecipitation and hydrothermal synthesis, which is achieved by adding a precursor mixture solution to a high pH basic solution, a uniform nano-sized NiO / YSZ composite is obtained in high yield, preferably at least 95%, more preferably at 100% (by weight). Obtained. NiO / YSZ composite prepared by the method according to an embodiment of the present invention is NiO is coated on the surface of the YSZ particles, the three-phase contact is increased to the gas reaction inside the negative electrode material. In addition, the NiO / YSZ composite is an increase in surface area as a nano-sized powder. The increase in the surface area also increases the three-phase contact point at which the gas reaction inside the anode material occurs and the contact area between the electrolyte and the cathode is increased, thereby reducing the interface resistance between the electrolyte and the cathode and improving the output performance of the solid oxide fuel cell. do.

Hereinafter, the present invention will be described in detail through examples.

Example 1

As a nickel precursor at room temperature, nickel chloride hexahydrate _{(Nickel chloride hexahydrate, NiCl 2?} 6H 2 O) 15.911g, zirconium as zirconium oxy chloride Titanium precursor octa hydrate _{(Zirconium oxychloride octahydrate, ZrOCl 2?} 9H 2 O) 12.048g and yttrium was dissolved in distilled water 500㎖ the yttrium chloride hexahydrate _{(yttrium chloride hexahyrate, YCl 3?} 6H 2 O) 0.986g as a precursor to prepare a precursor solution. Then, the precursor solution was added to 0.5 M NaOH 1L at room temperature, and adjusted to pH 13 using 0.5 M NaOH, followed by stirring at 300 rpm for 30 minutes. As a result, a mixed precipitate of nickel hydroxide, yttrium hydroxide and zirconium hydroxide was formed.

The reactant on which the mixed precipitate was formed was heat-treated at 130 ° C. for 72 hours to prepare NiO / YSZ composite powder. Thereafter, the mixture was washed three times by centrifugation using distilled water to remove Na ⁺ ions dissolved in the solution. After washing, the precipitate was taken and dried until completely dried at 60 ° C. The NiO / YSZ composite powders obtained in this example had an average diameter of 90 nm to 100 nm and a surface area of 5 m 2 / g to 10 m 2 / g.

A SEM photograph of the NiO / YSZ composite powder prepared in Example 1 is shown in FIG. 1. As can be seen from FIG. 1, a round-shaped NiO / YSZ powder having an average diameter of 100 nm or less was obtained. As described above, the NiO / YSZ composite obtained in Example 1 has an increased surface area as a nano-sized powder. It can be seen that the increase in the surface area also increases the three-phase junction (TPB) in which the gas reaction inside the anode material occurs.

Example 2

As a nickel precursor at room temperature, nickel chloride hexahydrate _{(Nickel chloride hexahydrate, NiCl 2?} 6H 2 O) 15.911g, zirconium as zirconium oxy chloride Titanium precursor octa hydrate _{(Zirconium oxychloride octahydrate, ZrOCl 2?} 9H 2 O) 12.048g and yttrium by dissolving yttrium chloride hexahydrate _{(yttrium chloride hexahydrate, YCl 3?} 6H 2 O) 0.986g of distilled water 500 ㎖ as a precursor to prepare a precursor solution. Then, the precursor solution was added to 600 mL of 0.5 M NaOH at room temperature, adjusted to pH 11 using 0.5 M NaOH, and stirred at 300 rpm for 30 minutes. As a result, a mixed precipitate of nickel hydroxide, yttrium hydroxide and zirconium hydroxide was formed.

The reactant on which the mixed precipitate was formed was heat-treated at 130 ° C. for 72 hours to prepare NiO / YSZ composite powder. Thereafter, the mixture was washed three times by centrifugation using distilled water to remove Na ⁺ ions dissolved in the solution. After washing, the precipitate was taken and dried until completely dried at 60 ° C. The NiO / YSZ composite powder obtained in Example 2 had an average diameter of 20 nm to 100 nm and a surface area of 10 m 2 / g to 15 m 2 / g.

SEM photographs of the NiO / YSZ composite powder prepared in Example 2 are shown in FIG. 2.

As can be seen in FIG. 2, NiO / YSZ having a coin and / or acicular structure was obtained by rapid reaction. Coin or needle-shaped NiO / YSZ can improve electrical performance by improving ion conductivity when applied to fuel cells.

Example 3

In this embodiment, the performance of the solid oxide fuel cell fabricated using the NiO / YSZ composite powder obtained in Example 1 and conventionally commercially available NiO and YSZ powder (conventional composite) as a negative electrode material was compared. Conventional commercially available NiO powders were used by mixing nickel oxide of JT Baker Co., Ltd. and 8 mol YSZ (trade name TZ-8Y) of TOSOH Co., Ltd. in a 1: 1 weight ratio.

Fabricating a cathode support having a thickness of 1 mm by using a tape casting method using the composite of Example 1 and the conventional composite, respectively; Forming an electrolyte layer (trade name TZ-8Y) having a thickness of 10 μm on the anode support using the same method and co-sintering at 1350 ° C .; A fuel cell was fabricated by applying a positive electrode (LSM: YSZ = 1: 1 weight ratio) to a thickness of 50 μm by screen printing on the electrolyte layer and sintering at 1000 ° C. The produced fuel cell was flowed into the cathode by flowing H ₂ containing 3 volume% of H ₂ O at 800 ° C., and the air was flowed to the anode. After 8 hours of reduction, the general cell and the mechanical layer were inserted using an electric loader. The current voltage curve of the unit cell was measured and shown in FIG. 3.

FIG. 3 shows changes in fuel cell voltage (linear in the graph of FIG. 3) and power density (curve in the graph of FIG. 3) according to current density. As shown in FIG. 3, it was confirmed that the power density and voltage of the fuel cell using the composite according to the present invention (Example 1) were improved compared to the fuel cell using the conventional composite (the conventional example). From this, it can be seen that the composite powder prepared by the method according to the present invention is manufactured in the form of a fine and uniform composite, thereby increasing the three-phase interface on the surface of the cathode, thereby improving the performance of the fuel cell.

Example 4

end. Method according to the invention

Example 1 above, except that NaOH, KOH, NH ₃ , (NH ₃ ) HCO ₃ and (NH ₃ ) ₂ CO ₃ solutions of 0.5 M each were used as the basic solution, and the precursor solution was varied according to the final target. YSZ, NiO and NiO / YSZ composites were prepared in the same manner. However, when (NH ₃ ) HCO ₃ and (NH ₃ ) ₂ CO ₃ basic solutions were used, the pH was adjusted using 0.5N NaOH.

(1) Preparation of YSZ

As a zirconium precursor at room temperature, zirconium oxychloride octa-hydrate _{(Zirconium oxychloride octahydrate, ZrOCl 2?} 9H 2 O) of distilled water for yttrium chloride hexahydrate _{(Yttrium chloride hexahydrate, YCl 3?} 6H 2 O) 0.986g 12.048g and an yttrium precursor A precursor solution dissolved in 500 ml was used. In the basic solution, the basicity was used in an amount such that the basic radical (hydroxy or ammonia) was 2 equivalents to the amount of the metal cation in the precursor solution.

(2) NiO manufacturing

In which the precursor solution of nickel chloride hexahydrate _{(Nickel chloride hexahyrate, NiCl 2?} 6H 2 O) 15.911g of distilled water 500 ml was used as a nickel precursor at room temperature. In the basic solution, the basicity was used in an amount such that the basic radical (hydroxy or ammonia) was 2 equivalents to the amount of the metal cation in the precursor solution.

(3) NiO / YSZ Composite Preparation

As basic solution, 0.5 M phosphorus NaOH, KOH, NH ₃ , (NH ₃ ) HCO ₃ and (NH ₃ ) ₂ CO ₃

It was prepared by the method of Example 1 using.

I. Neutralization Precipitation

A. Sediment Formation

In this method, 0.5 M NaOH, KOH, NH ₃ , (NH ₃ ) HCO ₃ and (NH ₃ ) ₂ CO ₃ solutions, respectively, were added to the precursor solution as a basic solution to form a precipitate.

(1) Preparation of YSZ

As a zirconium precursor at room temperature, zirconium oxychloride octa-hydrate _{(Zirconium oxychloride octahydrate, ZrOCl 2?} 9H 2 O) of distilled water for yttrium chloride hexahydrate _{(Yttrium chloride hexahydrate, YCl 3?} 6H 2 O) 0.986g 12.048g and an yttrium precursor A precursor solution dissolved in 500 ml was used. When 0.5 M NaOH, KOH, and NH ₃ were used as the basic solution, the basic solution was added to the precursor solution until pH 7. When 0.5 M of (NH ₃ ) HCO ₃ and (NH ₃ ) ₂ CO ₃ solutions were used as the basic solution, the basic solution was added in an amount equivalent to 2 equivalents of ammonia radical with respect to the metal cation in the precursor solution. And adjusted to pH 7 with 0.5M NaOH.

(2) NiO manufacturing

In which the precursor solution of nickel chloride hexahydrate _{(Nickel chloride hexahyrate, NiCl 2?} 6H 2 O) 15.911g of distilled water 500 ml was used as a nickel precursor at room temperature. When 0.5 M NaOH, KOH, and NH ₃ were used as the basic solution, the basic solution was added to the precursor solution until pH 7. When 0.5 M (NH ₃ ) HCO ₃ and (NH ₃ ) ₂ CO ₃ solutions are used as the basic solution, the basic solution is added in an amount such that the ammonia radical is 2 equivalents to the amount of metal cations in the precursor solution. And adjusted to pH 7 with 0.5M NaOH.

(3) NiO / YSZ Composite Preparation

In preparing the NiO / YSZ composite, the precursor mixed solution used in Example 1 was used. When 0.5 M NaOH, KOH, and NH ₃ were used as the basic solution, the basic solution was added to the precursor solution until pH 7 was obtained. When 0.5 M of (NH ₃ ) HCO ₃ and (NH ₃ ) ₂ CO ₃ solutions were used as the basic solution, the amount of the ammonia radical was 2 equivalents to the amount of the metal cation in the precursor solution. And adjusted to pH 7 with 0.5M NaOH.

B. Hydrothermal Synthesis

The precipitate obtained in step A was recovered by filtration and then calcined at 130 ° C. for 72 hours to prepare YSZ, NiO and NiO / YSZ composites, respectively.

The method a. ◎ When the reactants form a precipitate of 95% or more (by weight) in the process of manufacturing the composite according to (◎) (100% reaction), the reactants precipitate more than 70% and less than 95% ○ when the target product is formed, the reactant is precipitated at less than 70% and 50% or more to form the final target △, and the reactant is precipitated at less than 50% is formed as the final target X to Table 1 Shown in

precipitant
Kinds YSZ formation NiO Formation Complex Neutralization Precipitation Invention Neutralization Precipitation Invention Neutralization Precipitation Invention NaOH ○ ◎ ○ ◎ △ ◎ KOH ○ ◎ ○ ◎ △ ◎ NH ₃ ○ ◎ △ ○ X ○ (NH ₃ ) HCO ₃ ○ ◎ ○ ○ △ ○ (NH ₃ ) ₂ CO ₃ ○ ◎ △ ○ X ○

Since the precursor solution used for the preparation of YSZ is precipitated in large quantities in both the method according to the present invention and the neutralization precipitation method, YSZ is prepared in excellent yield in both the method and the neutralization precipitation method according to the present invention. However, high pH of 11 or higher is required to allow nickel to precipitate with high efficiency. Therefore, nickel is not sufficiently precipitated in the neutralization precipitation method, and loss of fine particles also occurs in the filtration process of the precipitate.

Therefore, NiO / YSZ composite containing nickel is produced in a good yield in the method according to the invention, it could be confirmed that a high yield cannot be produced by the neutralization precipitation method.

Claims (7)

Adding a precursor mixed solution of a nickel precursor, a yttrium precursor and a zirconium precursor to the basic solution and adjusting the pH to about 11 or more to form a mixed precipitate of nickel hydroxide, yttrium hydroxide and zirconium hydroxide; And
NiO / YSZ composite manufacturing method comprising the step of heat-treating the mixed precipitate to 80 ℃ to 180 ℃.
The method of claim 1, wherein the basic solution is at least one selected from the group consisting of NaOH, KOH, NH ₃ , (NH ₃ ) HCO _3, and (NH ₃ ) ₂ CO ₃ .
The method of claim 1, wherein the basic solution has a concentration of 0.05M to 0.5M.
The method of claim 1, wherein the nickel precursor in the mixed solution of the precursor is an amount of nickel cation is 0.01 M to 1.0 M, the yttrium precursor is an amount of yttrium cation is 0.001 M to 0.1 M, and the zirconium precursor NiO / YSZ composite is a zirconium cation is added in an amount of 0.05 M to 1.0M.
The method of claim 1, wherein the heat treatment is performed for 24 hours to 99 hours.
A NiO / YSZ composite having an average particle size of 20 nm to 100 nm prepared in the method of any one of claims 1 to 5.
The NiO / YSZ composite according to claim 6, wherein the NiO / YSZ composite has a surface area of 5 m 2 / g to 150 m 2 / g.

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