KR20180071673A - Preparation method of support of solid oxide fuel cell and support of solid oxide fuel cell - Google Patents

Abstract

The present invention relates to a method for manufacturing a solid oxide fuel cell support having uniform porosity and thermal expansion coefficient at each site by using a powder prepared by a liquid phase method and having uniform composition and structure, and a solid oxide fuel cell support manufactured therefrom. The method comprises the steps of: (a) manufacturing a mixed solution; (b) drying the mixed solution to manufacture a dried product; (c) pulverizing the product and sintering the same; (d) pulverizing the sintered product; (e) adding a solvent and a pore generating agent to manufacture slurries; (f) forming the slurries into a mold and drying and sintering the same.

Description

TECHNICAL FIELD [0001] The present invention relates to a method of manufacturing a solid oxide fuel cell backing, and a solid oxide fuel cell backing fabricated therefrom,

The present invention relates to a method for producing a solid oxide fuel cell backing and a solid oxide fuel cell backing made therefrom.

A fuel cell is a highly efficient, naturally friendly technology in which hydrogen contained in a hydrocarbon compound such as natural gas, coal gas, and methanol and oxygen contained in the air produce electrical energy by an electrochemical reaction. These fuel cells are largely divided into alkali type, phosphoric acid type, molten carbonate, solid oxide type, and polymer type depending on the type of electrolyte used. The phosphoric acid fuel cell (first generation) uses a phosphoric acid electrolyte while using hydrogen gas derived from a fossil fuel and oxygen in the air as a fuel, and the molten carbonate fuel cell (second generation) uses a molten salt , And the solid oxide fuel cell (third generation) operates at a high temperature of 600 to 1000 DEG C using solid ceramics as an electrolyte.

In a typical solid oxide fuel cell, a unit cell is disposed on a support, and a fuel electrode, an electrolyte, and an air electrode are sequentially stacked on the support. The solid oxide fuel cell has the advantages of being the most efficient among the fuel cells of the related art, having less pollution, requiring no fuel reformer, and capable of combined power generation. Such a solid oxide fuel cell is roughly classified into a cylindrical shape, a flat plate shape, and an integral shape depending on the shape thereof, and also has a flat shape having the advantages of a cylindrical shape and a flat shape. In the case of the flat tubular type, the power density and the productivity are excellent, and the electrolytic thin film can be formed.

On the other hand, in the solid oxide fuel cell, as the fuel permeation amount increases through the support, high output power generation is possible, so that the porous body and heat resistance of the support are indispensably required. Generally, the support is prepared using a mixed powder in which raw materials are mixed. At this time, if the raw materials are not mixed uniformly, voids are not formed uniformly in each portion of the support, so that the fuel efficiency may be lowered, and the thermal expansion coefficient may not be uniform and thermal shock may be a problem. Therefore, a lot of research is needed to solve the problems of such supports.

Patent No. 0648144

In order to solve the above-described problems, the present invention provides a method for producing a solid oxide fuel cell support having uniform porosity and thermal expansion coefficient at each site by using a powder prepared by a liquid phase method and uniformly mixed, and a solid oxide Type fuel cell support.

In order to accomplish the above object, the present invention provides a method for producing a water-soluble magnesium compound, comprising: (a) dissolving a water-soluble magnesium compound and a water-soluble aluminum compound in purified water to prepare a mixed aqueous solution; (b) drying the mixed aqueous solution at 80 to 200 ° C for 6 to 15 hours to obtain a dried product; (c) firstly pulverizing the dried material and then calcining at 1000 to 2000 ° C for 2 to 6 hours; (d) secondarily pulverizing the fired powder; (e) adding a solvent and a pore-forming agent to the second pulverized powder to prepare a slurry; And (f) shaping the slurry into a molded body, followed by drying and sintering the solid oxide fuel cell support.

Further, the present invention provides a solid oxide fuel cell scaffold prepared by the above method.

In the method for producing a solid oxide fuel cell support according to the present invention, water-soluble compounds used as raw materials are dissolved, followed by drying and pulverization, and uniformly mixed powders are used in the production of a molded article (support). When such a powder is mixed with a pore-forming agent to produce a molded article, the pores are uniformly formed, and the thermal expansion coefficient is uniform for each portion of the support. As a result, the solid oxide fuel cell to which such a support is applied can exhibit excellent performance with improved fuel and power efficiency.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a view of a support having a flat profile according to one embodiment of the present invention.
2 is a SEM image of a surface and a fracture surface of a support according to an embodiment of the present invention.

Hereinafter, the present invention will be described in detail.

In the solid oxide fuel cell, the fuel permeation amount is regulated through the support, thereby enabling high output power generation. Such a support is required to have heat resistance such that it can withstand the high heat generated at the time of power generation as well as the porosity through which the fuel can sufficiently permeate. Conventionally, since the support is prepared after directly mixing the powdery raw material, the powder is not uniformly mixed, and the physical properties (porosity, heat resistance) are different for each part of the support. When the support having different physical properties is applied to the solid oxide fuel cell, the fuel permeation amount and the heat resistance property are not constant at each site, and the efficiency of the fuel cell may be lowered and thermal shock may be a problem.

Accordingly, the present invention is characterized in that a powder having a uniform composition and structure is first prepared using a raw material of powder type, and a liquid phase method is used, and then a support is manufactured using the powder. More specifically, two or more water-soluble compounds are used as a raw material to prepare a mixed aqueous solution, followed by drying and pulverization to prepare powders having uniform composition and particle size. The powders are calcined and pulverized, And then the resulting slurry is molded into a support having uniform porosity and thermal expansion coefficient at each site.

≪ Method of producing solid oxide type fuel cell support >

A method of manufacturing a solid oxide fuel cell support according to an embodiment of the present invention includes the steps of: (a) preparing a mixed aqueous solution by dissolving a water-soluble magnesium compound and a water-soluble aluminum compound in pure water; (b) drying the mixed aqueous solution at 80 to 200 ° C for 6 to 15 hours to obtain a dried product; (c) firstly pulverizing the dried material and then calcining at 1000 to 2000 ° C for 2 to 6 hours; (d) secondarily pulverizing the fired powder; (e) adding a solvent and a pore-forming agent to the second pulverized powder to prepare a slurry; And (f) shaping the slurry into a compact, followed by drying and sintering.

Hereinafter, a method of manufacturing a solid oxide fuel cell support according to the present invention will be described. However, the solid oxide fuel cell support of the present invention is not limited to the following production method, and the steps of each step may be modified or optionally mixed as necessary.

(a): A water-soluble magnesium compound and a water-soluble aluminum compound are dissolved in purified water to prepare a mixed aqueous solution.

The water-soluble magnesium compound is a magnesium acetate _{((CH 3 CO 2) 2} ), magnesium hydroxide (Mg (OH) _2), magnesium chloride (MgCl _2), magnesium nitrate (Mg (NO _{3) 2)} and magnesium sulfate (MgSO ₄ ). ≪ / RTI > At this time, in order to prevent impurities from being formed in the mixed aqueous solution, the water-soluble magnesium compound is preferably magnesium acetate or magnesium hydroxide.

The water-soluble aluminum compound is ethyl aluminum _{(Al (CH 3 CO 2)} 3), aluminum hydroxide (Al (OH) _3), aluminum chloride (AlCl _3), aluminum nitrate (Al (NO _{3) 3)} and acid aluminum (Al (C ₇ H ₅ O ₃ ) ₃ ). At this time, in order to prevent impurities from being formed in the mixed aqueous solution, the water-soluble aluminum compound is preferably aluminum acetate or aluminum hydroxide.

Such a water-soluble magnesium compound and a water-soluble aluminum compound are prepared as a mixed aqueous solution using an appropriate amount so that they can be sufficiently dissolved in pure water. The above-mentioned mixed aqueous solution can be produced by using any conventional mixing method known in the art without limitation. At this time, the mixed aqueous solution may contain a water-soluble magnesium compound and a water-soluble aluminum compound in a weight ratio of 30 to 60: 40 to 70. Preferably, the mixing ratio of the water-soluble magnesium compound and the water-soluble aluminum compound is 40 to 50: 50 to 60.

(b): The mixed aqueous solution is dried at 80 to 200 ° C for 4 to 15 hours to prepare a dried product.

The mixed aqueous solution may be prepared as a dried product in which magnesium ions and aluminum ions are mixed with each other and dried to uniformly mix magnesium and aluminum.

If there is a rapid temperature change during drying, the purity may be lowered due to unreacted materials, and the mixed aqueous solution may be dried at 80 to 200 ° C for 4 to 15 hours. (B-1) stirring the mixed aqueous solution at 85 to 95 캜 for 2 to 5 hours and drying the mixture; (b-2) a second step of stirring the resultant of the first step at 96 to 120 ° C for 2 to 5 hours to dry; And (b-3) a third step of stirring and drying the resultant of the second step at 150 to 200 ° C for 2 to 5 hours. At this time, the mixed aqueous solution may be dried while stirring in a hot plate.

Such a dried material may be in a bulk form.

(c): The dried material is first pulverized and then calcined at 1000 to 2000 ° C for 2 to 6 hours.

The dried material is first pulverized using a finely pulverizing process known in the art without limitation.

Examples of the pulverization process include a ball mill, such as a tube mill, a compound mill, and a rod mill. For example, zirconium (Zr) balls are charged at a rate of 1 to 5 times the amount of the dried material and dried at 200 to 300 rpm for 2 to 12 hours using a solvent such as ethanol or acetone. The conditions of the ball mill may vary depending on the dried material to be pulverized. It can be pulverized. At this time, the primary pulverized powder may have an average particle size of 10 to 15 mu m.

These primary pulverized powders are charged into a crucible and fired in the atmosphere at 1000 to 2000 ° C for 2 to 6 hours. The powder may be reacted through a calcination process and converted to a magnesium-aluminum reactant (e.g., MgAl ₂ O ₄ ).

(d): The fired powder is secondarily pulverized.

The powder obtained in the step (c) is in a state of increased particle size due to the firing process and is secondly pulverized to make it into a powder. The secondary pulverization can be carried out without any limitation in the coarsely pulverizing process and / or the pulverizing process known in the art.

A cutter mixer may be used as the coarse grinding process. For example, 500 g of powder per batch may be milled at 2,000 to 3,000 rpm for 1 to 10 minutes. At this time, if the powder is pulverized for more than 10 minutes, the powder may be contaminated due to the inclusion of foreign matter.

As the pulverization process, a jet mill or a planetary mill may be used. At this time, for example, zirconium balls (Ø15 mm) can be pulverized at 200 to 500 rpm for 5 to 30 minutes by feeding the powder at a rate of 3 to 6 times the amount of the powder.

In order to obtain the fired powder as a fine powder having a size of 6 탆 or less, it is preferable to carry out both of the coarse grinding and the fine grinding by the secondary grinding.

This second milled powder is a reaction product in which magnesium and aluminum are uniformly mixed and has a fine particle size, wherein the average particle size may be 1 to 6 탆, preferably 2 to 4 탆.

(e): adding a solvent and a solvent to the second pulverized powder Pore forming agent  To prepare a slurry.

The solvent may be any conventional solvent known in the art without limitation, and examples thereof include ammonia water; Alcohol solvents such as ethanol, methanol and isopropyl alcohol; Acetone, ketone solvents such as methyl ethyl ketone, and the like. The solvent may be added in an amount of 15 to 30 parts by weight based on 100 parts by weight of the second pulverized powder.

The pore-forming agent may be selected from the group consisting of carbon powder, carbon black, acetylene black, activated carbon, natural graphite, artificial graphite, graphene, carbon fiber, fullerene, carbon nanotube, carbon nanowire, ≪ / RTI > The pore former may be added in an amount of 5 to 15 parts by weight based on 100 parts by weight of the second pulverized powder. At this time, a dispersant may be further added to prevent aggregation of the pore-forming agent. The dispersing agent may be any conventional dispersing agent known in the art and may be used in an amount of 0.1 to 2 parts by weight based on 100 parts by weight of the second pulverized powder.

Conventional additives such as a binder and a plasticizer may be added to the secondary pulverized powder in addition to the solvent and the pore-forming agent.

The binder may be at least one selected from the group consisting of perfluorinated polymers, benzimidazole polymers, polyimide polymers, polyetherimide polymers, polyphenylene sulfide polymers, polysulfone polymers, polyether sulfone polymers, and polyether ketone polymers Hydrophobic polymers; Phenolic resins such as novolak type phenol resins and resol type phenol resins; Cellulose such as methylcellulose, propylcellulose, and the like.

The plasticizer may be polyethylene glycol (PEG), polyethylene oxide, polypropylene glycol, ethylene glycol, propylene glycol, poly (vinyl acetate-co-vinyl alcohol) and the like. Such an additive may be added in an amount of 3 to 7 parts by weight based on 100 parts by weight of the powder obtained by the second pulverization.

A solvent, a porogen and an additive are mixed together with the second pulverized powder, followed by kneading to prepare a slurry. At this time, the kneading step may be repeated one or more times so that the slurry can be uniformly produced.

(f): The slurry As a molded article  After molding, it is dried and sintered.

The slurry is formed into a desired shape of the formed body. At this time, the shaped body may be cylindrical, flat plate, integral or flat tube depending on the shape of the solid oxide fuel cell. The molding may be performed by any conventional molding method known in the art without limitation, and may be, for example, extrusion molding, press molding, or the like. In the case of the extrusion molding, a screw extruder may be used.

The compact is dried in air and then sintered to produce the final support. More specifically, (f-1) a step of drying the molded body in the air for 10 to 28 hours; And (f-2) sintering the result of the first step at 1000 to 1500 ° C for 4 to 8 hours. At this time, it may be room temperature at the time of drying the formed body, and may be atmosphere or oxygen atmosphere at the time of sintering.

The method of producing such a solid oxide fuel cell backing is a method of preparing a solid oxide fuel cell backing by using a powder having a uniform composition and structure prepared by a liquid phase method using magnesium and aluminum in powder form and thus compared with a powder in which a conventional magnesium powder and aluminum powder are directly mixed Since a high mixing ratio and a uniform particle size are obtained, a support having uniform porosity and thermal expansion coefficient can be produced.

≪ Solid oxide type fuel cell support >

The solid oxide fuel cell support manufactured according to the above-described method provides a passage for supplying fuel while supporting the fuel cell, and may be cylindrical, flat plate, integral or flat pipe. Referring to Fig. 1, the support member 10 having a flat tubular shape includes a fuel supply passage 20, and the shape of the fuel supply passage may be various shapes such as a circle, an ellipse, a pentagon, a hexagon,

Such a support has a porosity of 30% or more and can have the same fuel permeability in one support since it has a uniform porosity at each site. In addition, since the support has a uniform thermal expansion coefficient at each site, it can exhibit the same heat resistance characteristics in one support. Therefore, the solid oxide fuel cell to which the support is applied according to the present invention has excellent fuel efficiency and power generation efficiency due to uniform porosity and thermal expansion coefficient.

Hereinafter, the present invention will be described concretely with reference to Examples. However, the following Examples illustrate only one embodiment of the present invention, and the scope of the present invention is not limited by the following Examples.

[ Example  1] Preparation of Support

Magnesium acetate and aluminum acetate were dissolved in pure water at a weight ratio of 42:58 to prepare a mixed aqueous solution. The mixed aqueous solution was dried by stirring on a hot plate at 90 캜 for 4 hours, at 100 캜 for 4 hours and at 180 캜 for 4 hours. The dried material was first pulverized by a ball mill (powder: ball = 1: 3 weight ratio, 300 rpm, 1 hour), and then calcined at 1500 DEG C for 4 hours under a nitrogen atmosphere. The fired powder (particle size: 12.992 탆) was pulverized by a secondary cutter mixer (powder 500 g / batch, 2500 rpm, 5 minutes) and pulverized with a planetary mill (powder: ball = 1: 5 weight ratio, 350 rpm, 15 minutes) Respectively. 2 g of the pulverized powder (particle size: 21.148 탆), 500 g of ethanol (solvent), 200 g of carbon (porogen), 10 g of PVA (dispersant), 80 g of methyl cellulose (binder) and 5 g of PEG To prepare a slurry. The slurry was extruded into a flat tubular shaped body. The formed body was dried in air at room temperature for 24 hours and then sintered at 1300 ° C for 6 hours to prepare a final support.

At this time, the particle size of the powder was measured by dispersing ultrasonic waves at 2500 rpm in an ethanol atmosphere using a micro particle size analyzer (PSA).

[ Comparative Example  1] Preparation of Support

Magnesium oxide and aluminum oxide were mixed at a weight ratio of 70:30 and then pulverized with a ball mill (weight ratio of powder: ball = 1: 3, 250 rpm, 2 hours) to prepare a mixed powder (particle size: 21 탆). 2 kg of the mixed powder, 500 g of ethanol (solvent), 200 g of carbon (pore forming agent), 10 g of PVA (dispersant), 80 g of methylcellulose (binder) and 5 g of PEG (plasticizer) were added and kneaded to prepare a slurry. The slurry was used to extrude into a flat tubular shaped body. The molded body was dried in the air at room temperature for 24 hours and then sintered at 1300 ° C for 6 hours to prepare a final support.

[ Experimental Example  1] Cross section observation

Surface and fracture surfaces of the support prepared in Example 1 and Comparative Example 1 were observed with a scanning electron microscope (SEM), and the results are shown in Fig.

As shown in FIG. 2, it was found that the support according to the present invention (Example 1) had uniform pores as compared with the support prepared according to the conventional method (Comparative Example 1).

[ Experimental Example  2] Porosity measurement

The porosity of the support prepared in Example 1 and Comparative Example 1 was measured and the results are shown in Table 1 below.

At this time, the porosity of the specimen manufactured to have a size of 10 * 10 mm was measured by mercury pressurization using Proscimer (Micromeritics).

Example 1 Comparative Example 1 Porosity (%) 30.03 20.59

 As shown in Table 1, it was found that the support according to the present invention (Example 1) had a higher porosity than the support (Comparative Example 1) by the conventional method.

[ Experimental Example  3] Measurement of thermal expansion coefficient

The thermal expansion coefficients of the supports prepared in Example 1 and Comparative Example 1 were measured and the results are shown in Table 2 below.

At this time, one support was divided into the first half, the middle half, and the second half to prepare specimens each having a size of 8 * 5 * 5 mm. These specimens were processed to a temperature of 1400 ° C using a dilatometer (NETZSCH) and the thermal expansion coefficient was measured by changing the specimen.

Thermal Expansion Coefficient (ppm / k) Example 1 Comparative Example 1 Psalter First half 12.07 10.06 Middle 12.67 13.93 Second half 12.41 14.81

As shown in Table 2, it was confirmed that the support according to the present invention (Example 1) had a uniform thermal expansion coefficient as compared with the support (Comparative Example 1) by the conventional method.

10: Support
20: fuel supply passage

Claims (9)

(a) preparing a mixed aqueous solution by dissolving a water-soluble magnesium compound and a water-soluble aluminum compound in purified water;
(b) drying the mixed aqueous solution at 80 to 200 ° C for 6 to 15 hours to obtain a dried product;
(c) firstly pulverizing the dried material and then calcining at 1000 to 2000 ° C for 2 to 6 hours;
(d) secondarily pulverizing the fired powder;
(e) adding a solvent and a pore-forming agent to the second pulverized powder to prepare a slurry; And
(f) molding the slurry into a compact, drying and sintering
Wherein the solid oxide fuel cell support comprises a solid oxide fuel cell. The method according to claim 1,
The (a) water-soluble magnesium compound is a magnesium acetate in step _{((CH 3 CO 2) 2} ), magnesium hydroxide (Mg (OH) _2), magnesium chloride (MgCl _2), magnesium nitrate (Mg (NO _{3) 2),} and Magnesium sulfate (MgSO ₄ ), and the like,
Water-soluble aluminum compound is ethyl aluminum _{(Al (CH 3 CO 2)} 3), aluminum hydroxide (Al (OH) _3), aluminum chloride (AlCl _3), aluminum nitrate (Al (NO _{3) 3)} and acid aluminum (Al ( C ₇ H ₅ O ₃ ) ₃ ). The method according to claim 1,
Wherein the mixed aqueous solution of the step (a) is prepared by mixing the water-soluble magnesium compound and the water-soluble aluminum compound at a weight ratio of 30 to 60:40 to 70 to dissolve the solid solution. The method according to claim 1,
The step (b)
(b-1) stirring the mixed aqueous solution at 85 to 95 캜 for 2 to 5 hours and drying;
(b-2) a second step of stirring the resultant of the first step at 96 to 120 ° C for 2 to 5 hours to dry; And
(b-3) The third step of stirring the resultant of the second step at 150 to 200 DEG C for 2 to 5 hours to dry
Is carried out in sequence. The method according to claim 1,
Wherein a ball mill is used for the primary pulverization in the step (c). The method according to claim 1,
Wherein the second pulverization in the step (d) uses a cutter mixer and / or a planetary mill. The method according to claim 1,
Wherein the step (e) further comprises adding a binder and / or a plasticizer to the second pulverized powder and kneading the same. The method according to claim 1,
The step (f)
(f-1) drying the shaped body in the air for 10 to 28 hours; And
(f-2) a second step of sintering the result of the first step at 1000 to 1500 ° C for 4 to 8 hours
Is carried out in sequence. A solid oxide fuel cell support prepared by the method of any one of claims 1 to 8.

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