KR20150052662A - anode, anode-supported electrolyte film, fuel cell and method of preparing anode-supported electrolyte film - Google Patents

Abstract

Disclosed are an anode, an anode-supported electrolyte film, a fuel cell, and a manufacturing method of an anode-supported electrolyte film. The disclosed anode includes a nano composite including scandia stabilized zirconia (ScSZ) particles and Ni-based nanoparticles coated on the surface of the ScSZ particles.

Description

[0001] The present invention relates to an anode, an anode-supported electrolyte membrane, a fuel cell-supported electrolyte membrane, a fuel cell, and an anode-

A fuel electrode, a fuel electrode-supported electrolyte membrane, a fuel cell, and a method for manufacturing an anode-supported electrolyte membrane are disclosed. More particularly, a method for manufacturing a fuel electrode, a fuel electrode-supported electrolyte membrane, a fuel cell, and an anode-supported electrolyte membrane including a nanocomposite comprising Ni nanoparticles coated on the surface of ScSZ (Scandia Stabilized Zirconia) particles is disclosed .

Conventional solid oxide fuel cell (SOFC) technology is commercialized because of its high operating temperature of 800 to 1,000 ° C., stability problems of materials and components due to high temperature operation, and economical problems due to use of expensive high temperature heat resistant materials it's difficult. Therefore, it is necessary to develop a low-temperature SOFC technology capable of maintaining high performance and high efficiency at a temperature lower than the conventional SOFC operating temperature in order to secure system stability and economical efficiency at a commercial level.

Among the fuel cell materials for lowering the operating temperature of the high temperature, a new composition electrolyte of ceria or perovskite type which is excellent in ion conductivity even at the middle and low temperature has been attracting attention. However, the electrolyte of the new composition developed so far has a disadvantage in that the manufacturing process is not simple, the mechanical strength is weak, and the thermal and chemical stability is poor at high temperature.

The primary research direction of the design of a single cell to lower the operating temperature of the SOFC is the thinning of the electrolyte layer. Yttria stabilized zirconia (YSZ) has an ionic conductivity of 0.005 S / cm (600 ° C). It is difficult to obtain effective conductivity at low temperatures unless the thickness of the electrolyte layer is reduced to 5 μm. Therefore, developing a manufacturing process that overcomes the limit of the formable thickness is a core technology in the development of a middle-low-temperature fuel cell. In order to manufacture such a thin film type electrolyte, a wet process such as dip coating, spin coating, electrophoretic deposition (EPD), and spraying may be performed on the anode. And development of an anode-supported electrolyte membrane in which an electrolyte layer is coated by thin film forming processes such as sputtering, E-beam, and electrochemical vapor deposition (EVD). However, in developing such an anode-supported electrolyte membrane, it is difficult to obtain a uniform film thickness without defects, and technical problems such as limitations on the thickness reduction of the thin film formed on the porous electrode, and economical problems such as an increase in the process ratio, The standardization of the manufacturing process of the electrolyte thin film has not been made yet.

On the other hand, attempts have been made to develop a technology for thinning an electrolyte layer for high performance of an SOFC by using high-efficiency tape casting, lamination and co-firing processes.

Tape casting, laminating and co-firing processes are mainly used for mass production and continuous production of electronic components such as MLCC (Multi-Layer Ceramic Capacitor) and LTCC (Low Temperature Co-firing Ceramics) However, the co-firing of the heterogeneous bonding material has a great advantage in terms of process cost reduction. Therefore, tape casting, lamination and co-firing processes are considered to be very attractive processes for the production of single cells.

When an anode-supported electrolyte membrane is manufactured by using a conventional unit cell manufacturing process, additional processes such as three or more heat treatment processes, dip coating and pressing are required for formation of components such as a fuel electrode, a functional layer and an electrolyte layer Thereby causing a large increase in the process ratio. However, when tape casting, lamination and co-firing process are used, single cells can be produced by a single heat treatment process and a single manufacturing process, thus establishing a low-cost, high-efficiency manufacturing process base.

On the other hand, when a metal serving as a catalyst for oxidation of a fuel is used as an anode material, it is required to improve the microstructure change due to migration of the metal atoms and Ostwald ripening phenomenon during long-term operation, reduction of three phase boundaries (TPB) And the degradation due to the increase of the electrode resistance causes the life of the battery to be reduced. Therefore, it is necessary to control the anode material and the microstructure to solve this problem in order to increase the life span of the battery.

Also, in the co-firing process, the flat plate type unit cell is warped and peeled due to the difference in thermal expansion coefficient between the different materials. This reduces the contact area between the unit cell and the current collector, thereby deteriorating the performance of the stack, and is a major cause of increasing the possibility of destruction of the unit cell in manufacturing the stack. Therefore, excellent flatness and high strength are important factors in the development of high performance and high reliability (long term stability) SOFC.

One embodiment of the present invention provides a fuel electrode comprising a nanocomposite comprising Ni-based nanoparticles coated on the surface of ScSZ (Scandia Stabilized Zirconia) particles.

Another embodiment of the present invention provides an anode-supported electrolyte membrane comprising the nanocomposite.

Another embodiment of the present invention provides a fuel cell comprising the nanocomposite.

Another embodiment of the present invention provides a method for producing the anode-supported electrolyte membrane.

According to an aspect of the present invention,

An anode comprising a nanocomposite, wherein the nanocomposite comprises a ScSZ (Scandia Stabilized Zirconia) particle and a Ni-based nanoparticle coated on the surface of the ScSZ particle.

The Ni nanoparticles may include at least one of Ni nanoparticles and NiO nanoparticles.

The size of the ScSZ particles may be 0.2-1.0 탆, and the size of the Ni nanoparticles may be 10-100 nm.

The nanocomposite may further include YSZ (Yttria Stabilized Zirconia) nanoparticles coated on the surface of the ScSZ particles.

The size of the YSZ nanoparticles may be 10-100 nm.

The BET specific surface area of the nanocomposite may be 10 to 20 m ² / g.

According to another aspect of the present invention,

Wherein the nanocomposite comprises a ScSZ (Scandia Stabilized Zirconia) particle and a Ni-based nanoparticle coated on the surface of the ScSZ particle.

The fuel electrode supporting electrolyte membrane includes a fuel electrode and an electrolyte layer disposed on the fuel electrode.

The nanocomposite may be included in the fuel electrode.

The thickness of the fuel electrode may be 100 to 1,000 占 퐉, and the thickness of the electrolyte layer may be 5 to 10 占 퐉.

The anode-supported electrolyte membrane may further include a functional layer disposed between the anode and the electrolyte layer, and the nanocomposite may be included in the functional layer.

The thickness of the functional layer may be 5 to 100 mu m.

According to another aspect of the present invention,

And a fuel electrode supporting electrolyte membrane.

According to another aspect of the present invention,

(S10) producing a plurality of sheets having casting direction lines by using a tape casting method; And

(S20) of laminating the plurality of sheets in order so that the casting direction lines of the respective sheets cross each other to obtain a first laminate,

Wherein the sheet comprises a nanocomposite and the nanocomposite comprises Scandium Stabilized Zirconia (ScSZ) particles and Ni nanoparticles coated on the surface of the ScSZ particles.

In the step S20, the plurality of sheets may be sequentially stacked such that the casting direction lines thereof are perpendicular to each other clockwise or counterclockwise along the thickness direction of the first laminate.

Wherein the sheet is a sheet for forming a fuel electrode, and the method for producing the fuel electrode-supported electrolyte membrane comprises: after the step (S20), laminating sheets for forming an electrolyte layer on the first laminate using a tape casting method, (S30) of obtaining a second laminate including the first laminate, and a step (S40) of simultaneously firing the second laminate.

Each of the fuel electrode-forming sheets may have a thickness of 25 to 100 mu m.

The step (S40) may be performed while applying a pressure of 5 to 15 g / cm < ² > onto the second laminate.

The step (S40) may be performed at a temperature of 1,300 to 1,450 ° C.

Wherein the sheet is a sheet for forming a functional layer, and the step (S20) is a step of forming a sheet for forming a plurality of functional layers on a third stacked body produced by stacking a plurality of sheets for fuel electrode formation, May be carried out by lamination.

The thickness of each functional layer-forming sheet may be 5 to 100 mu m.

The tape casting method of the step S10 is carried out using a slurry. The slurry is obtained by mixing toluene and alcohol at a ratio of 4: 1 by weight to obtain a liquid medium, adding 100 parts by weight of the liquid medium 20 to 200 parts by weight of a nanocomposite and 10 to 50 parts by weight of a pore former to obtain a first mixture; mixing the first mixture with 40 to 50 parts by weight per 100 parts by weight of the sum of the nanocomposite and the pore- 1 to 5 parts by weight of a dispersant is added to and mixed with 100 parts by weight of the sum of the nanocomposite and the pore-forming agent to the second mixture to obtain a third mixture ≪ / RTI >

The anode according to one embodiment of the present invention may have a high linear shrinkage, porosity, mechanical strength and electrical conductivity.

In addition, the fuel cell-supported electrolyte membrane and the fuel cell according to an embodiment of the present invention may have reduced warping and peeling, and may have a high flatness.

1 is a schematic view of a nanocomposite included in a fuel electrode according to an embodiment of the present invention.
2 is a schematic view of a fuel electrode according to an embodiment of the present invention.
FIGS. 3A and 3B are views for explaining a method of stacking an anode-supported electrolyte membrane according to an embodiment of the present invention and a conventional anode-supported electrolyte membrane according to an embodiment of the present invention.
4 is a view for explaining warpage suppression by pressurization during the co-firing process.
5 is a graph showing a heat treatment schedule for burn-out of an anode-supported electrolyte membrane.
FIG. 6 is a graph showing a change in maximum diameter of Ni particles according to heat cycle recovery when the anode according to an embodiment of the present invention is heat-treated.
FIGS. 7A and 7B are scanning electron microscope (SEM) photographs showing changes in microstructure due to heat cycle recovery when the fuel electrode and the conventional anode according to an embodiment of the present invention are heat-treated.
FIG. 8 is a graph showing a change in electric conductivity according to heat cycle recovery when the anode according to an embodiment of the present invention is heat-treated.
FIGS. 9A and 9B are graphs illustrating the height variation of the anode-supported electrolyte membrane and the anode anode-supported electrolyte membrane according to an embodiment of the present invention, respectively.

Hereinafter, a fuel electrode according to an embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a schematic view of a nanocomposite included in a fuel electrode according to an embodiment of the present invention, and FIG. 2 is a schematic diagram of a fuel electrode according to an embodiment of the present invention.

1 and 2, an anode according to an embodiment of the present invention includes a nanocomposite, wherein the nanocomposite comprises ScSZ (Scandia Stabilized Zirconia) particles and Ni nanoparticles coated on the surface of the ScSZ particles . In the present specification, " Ni-based nanoparticles " means Ni metal nanoparticles, Ni metal oxide nanoparticles or a combination thereof.

The ScSZ particles have excellent conductivity and high linear shrinkage. In the present specification, the term "linear shrinkage ratio" means that the amount of change in length (ΔL) in one direction due to the heat treatment is expressed as a percentage of the length (Lo) in one direction before heat treatment.

The size of the ScSZ particles may be 0.2 to 1.0 탆, for example, 0.3 to 0.8 탆.

The Ni nanoparticles may have a size of 10 to 100 nm, for example, 30 to 100 nm.

A plurality of the Ni-based nanoparticles are brought into contact with each other to serve as electron transfer paths. Also, since a plurality of the Ni-based nano-particles adhere to the surface of the ScSZ particles and are fixed in position, even when the fuel electrode is used at a high temperature for a long time, no agglomeration phenomenon occurs between the Ni-based nanoparticles and high conductivity, porosity, Strength and durability can be provided.

The nanocomposite may further include YSZ (Yttria Stabilized Zirconia) nanoparticles coated on the surface of the ScSZ particles. The YSZ nanoparticles are disposed between the Ni nanoparticles to increase the distance between the Ni nanoparticles while maintaining contact between the Ni nanoparticles, thereby further suppressing aggregation between the Ni nanoparticles . The YSZ nanoparticles may also be attached to the surface of the ScSZ grains and fixed in position.

The size of the YSZ nanoparticles may be 10-100 nm, for example, 30-100 nm.

The BET specific surface area of the nanocomposite may be 10 to 20 m ² / g, for example, 15 to 20 m ² / g. When the BET specific surface area of the nanocomposite is within the above range, the three-phase interface of the fuel electrode increases, and when the slurry containing the nanocomposite is produced, a stable colloidal dispersion phase can be obtained. Means takes place the interface in the present specification, "three-phase interface" is also electrochemical oxidation _{^{(H 2 + O 2 - -}} = H 2 O + 2e) of hydrogen to be used as fuel as shown in an enlarged view of a second .

Since the fuel electrode contains ScSZ particles having excellent conductivity, even if including Ni-based nanoparticles and YSZ nanoparticles having a relatively large particle size, they have excellent conductivity as a whole. In addition, the fuel electrode has a high linear shrinkage ratio due to ScSZ particles having a large linear shrinkage ratio. In addition, the fuel electrode has a high strength because it contains a nanocomposite having high strength.

Hereinafter, an anode-supported electrolyte film according to an embodiment of the present invention will be described in detail.

The anode-supported electrolyte membrane according to an embodiment of the present invention includes the nanocomposite.

The anode-supported electrolyte membrane may include a fuel electrode and an electrolyte layer disposed on the anode.

The nanocomposite may be included in the fuel electrode. In this case, the fuel electrode includes a nanocomposite (hereinafter referred to as " NiO-YSZ / ScSZ ") containing the Ni-based nanoparticles and YSZ nanoparticles coated on the surface of the ScSZ particles, Or ScSZ.

The thickness of the fuel electrode may be 100 to 1,000 mu m. When the thickness of the fuel electrode is within the above range, the permeability of the fuel gas to the fuel electrode can be made smooth, while the strength of the fuel electrode is high and the reaction area where reduction of the fuel in the fuel electrode occurs is sufficiently large.

The thickness of the electrolyte layer may be 5 to 10 mu m. If the thickness of the electrolyte layer is within the above range, the strength of the electrolyte layer is high and the gas permeation suppression efficiency by the electrolyte layer is high, and the electrical resistance of the electrolyte layer may be low.

The anode-supported electrolyte membrane may have high conductivity, porosity, mechanical strength, and durability by including the nanocomposite. In addition, since the thermal expansion coefficient of the fuel electrode and the electrolyte layer and the linear shrinkage ratio thereof are similar to each other, the anode-supported electrolyte membrane can have a reduced flatness and warpage.

The anode-supported electrolyte membrane may further include a functional layer disposed between the anode and the electrolyte layer, and the nanocomposite may be included in the functional layer. In this case, the fuel electrode includes a mixture of Ni nanoparticles and YSZ nanoparticles (hereinafter referred to as "NiO-YSZ"), and the functional layer includes the Ni nanoparticles coated on the surface of the ScSZ particles (Hereinafter referred to as " NiO / ScSZ ") or NiO-YSZ / ScSZ, and the electrolyte layer may include YSZ or ScSZ.

The functional layer prevents or suppresses a reaction between the fuel electrode and the electrolyte layer to prevent or suppress the occurrence of a non-conductive layer (not shown) therebetween.

The thickness of the functional layer may be 5 to 100 mu m. When the thickness of the functional layer is within the above range, the specific surface area of the functional layer is sufficiently large, and the fuel gas can be smoothly transmitted through the functional layer.

When the fuel electrode-supported electrolyte membrane further comprises the functional layer, the fuel electrode-supported electrolyte membrane has a low linear shrinkage and peeling phenomenon because the linear shrinkage ratios of the fuel electrode, the functional layer, and the electrolyte layer are similar to each other, .

Hereinafter, a fuel cell according to an embodiment of the present invention will be described in detail.

The fuel cell according to an embodiment of the present invention includes the anode-supported electrolyte membrane. Specifically, the fuel cell includes the anode-supported electrolyte membrane and a buffer layer and an air electrode sequentially disposed thereon. The buffer layer and the air electrode may be those known in the art.

The fuel cell has the advantages of the anode-supported electrolyte membrane.

Hereinafter, a method for manufacturing an anode-supported electrolyte membrane according to an embodiment of the present invention will be described in detail with reference to the drawings.

FIGS. 3A and 3B are views for explaining a method of laminating an anode supporting electrolyte membrane according to an embodiment of the present invention and a cathode anode supporting electrolyte membrane according to the prior art, and FIG. 4 is a cross- Fig.

A method of manufacturing an anode-supported electrolyte membrane according to an embodiment of the present invention includes the steps of: (S10) forming a plurality of sheets having casting direction lines by using a tape casting method; and And a step (S20) of laminating the plurality of sheets in order to obtain a first laminate. In the present specification, the term " casting direction line " means a virtual arrow indicating the direction in which the base tape moves when performing tape casting.

The sheet comprises the nanocomposite.

The tape casting method of step S10 may be performed using a slurry (or a paste).

The slurry is prepared by mixing toluene and alcohol in a ratio of 0: 10 to 10: 0 by weight (for example, 4: 1) by weight to obtain a liquid medium. To 100 parts by weight of the liquid medium, And 10 to 50 parts by weight of a pore forming agent are added and mixed to obtain a first mixture, 40 to 50 parts by weight of a binder is added to the first mixture in 100 parts by weight of the sum of the nanocomposite and the pore-forming agent And mixing and mixing the second mixture with 1 to 5 parts by weight of a dispersant based on 100 parts by weight of the sum of the nanocomposite and the pore-forming agent to obtain a third mixture, .

The nanocomposite comprises dispersing a nickel salt (and optionally a zirconium salt and an yttrium salt) in an aqueous medium to obtain a first mixture, adding an organic acid to the first mixture, heating the mixture at 25 to 100 ° C for 1 to 12 hours And stirring the mixture to obtain a second mixture containing a metal organic complex; adding a polyhydric alcohol to the second mixture; heating and stirring the mixture at 25 to 110 ° C for 2 to 12 hours to progress the esterification reaction; , Obtaining a fourth mixture by adding ScSZ powder to the third mixture, heating and stirring the fourth mixture at 80 to 200 DEG C for 1 to 6 hours to obtain a third mixture containing the aqueous medium Evaporating to obtain a solid, firing the solid at 400-1,000 DEG C for 1 to 12 hours, and milling the fired solids in an alcohol.

The nickel salt may be a _{Ni (NO 3) 2 · 6H} 2 O.

The zirconium salt may be ZrO (NO ₃ ) ₂ .xH ₂ O (x is 1 to 4).

The yttrium salt may be Y (NO ₃ ) ₃ .6H ₂ O.

The organic acid may include at least one compound selected from the group consisting of citric acid, acetic acid, butyric acid, palmitic acid, oxalic acid and tartaric acid.

The polyhydric alcohol may include at least one compound selected from the group consisting of glycerol, ethylene glycol, propylene glycol, sorbitol and dipropylene glycol.

The alcohol may be ethanol.

The pore-forming agent may include at least one compound selected from the group consisting of carbon black, graphite, starch, polystyrene, and polymethyl methacrylate (PMMA).

The binder may comprise polyvinyl butyral (PVB).

The dispersant may include M1201 from Ferro.

3A, the casting direction lines (the arrows in Fig. 3A) are formed in the thickness direction of the first laminate in the clockwise or counterclockwise direction To be perpendicular to each other (for example, to face four directions of east, west, south, and north).

By flattening the plurality of sheets in the same manner as described above, the flatness of the first laminate can be improved. Specifically, when performing the tape casting using the slurry, the evaporation rate of the liquid medium contained in the slurry is fast at both ends of the large sheet formed on the base tape and slower toward the center of the large sheet, The pressure acting on the blade of the casting apparatus becomes smaller at both ends of the blade and toward the central portion of the blade. Therefore, the thickness of the large sheet tends to be thicker at both ends of the large sheet and thicker toward the center of the large sheet. Therefore, when the large sheet is cut to provide a plurality of small sheets, and then the plurality of small sheets are stacked by the same method as in Fig. 3A, the first stacked layer Sieve can be obtained. 3B shows a method in which the plurality of sheets are stacked in order so that their casting direction lines (the arrows in Fig. 3B) are juxtaposed to each other along the thickness direction of the first laminate.

In the present specification, the term "flatness" refers to the case where the height of the center of a specimen (for example, the first laminate) having a length of 5 cm is used as a reference point (Hereinafter referred to as " height deviation ") between the maximum height and the minimum height of the specimen. The smaller the height deviation is, the better the flatness is.

The sheet in the step (S10) may be a sheet for forming a fuel electrode. In this case, after the step (S20), a step of laminating an electrolyte layer-forming sheet produced by using a tape casting method on the first laminate to obtain a second laminate including the first laminate S30), and simultaneously firing the second laminate (S40). In the present specification, "simultaneously firing" means simultaneously firing two or more sheets (for example, a sheet for forming a fuel electrode and a sheet for forming an electrolyte layer) included in the second laminate.

By simultaneously firing the second layered product as described above, the manufacturing cost of the fuel electrode supporting electrolyte membrane can be reduced.

Each of the fuel electrode-forming sheets may have a thickness of 25 to 100 mu m. When the thickness of each of the fuel electrode-forming sheets is within the above range, the production of each of the fuel electrode-forming sheets is easy, and the number of the sheets for forming each of the fuel electrode constituting the first layer- The flatness can be improved. For reference, as the number of the fuel electrode-forming sheets constituting the first laminate increases, the height deviation derived from each fuel electrode-forming sheet accumulates and the flatness of the first laminate finally formed It gets worse.

The step (S40) is for densifying the electrolyte layer included in the second laminate. In addition, the different types of sheets included in the second laminate may be firmly coupled to each other by the step S40.

Also, even if the second laminate is fired at a high temperature in step S40, since the thermal expansion coefficient and thus the linear shrinkage ratio of the sheets included in the second laminate are similar to each other, Does not occur.

The step (S40) may be performed while applying a pressure of 5 to 15 g / cm < ² > onto the second laminate. The pressure can be uniformly applied to the entire upper surface of the second laminate as shown in Fig. If the pressure is within the above range, warping of the second laminate during co-firing in step S40 is suppressed, and flatness can be improved.

4 includes a fuel electrode 10, a functional layer 20, and an electrolyte layer 30 which are sequentially disposed between two setters 41 and 42. The second set of layers in Fig. Is applied. The setters 41 and 42 may be porous zirconia setters.

The step (S40) may be performed at a temperature of 1,300 to 1,450 ° C. The temperature is within the above range and the various laminates included in the second laminate are well connected without undue smearing so that the second laminate can have sufficient strength.

The sheet in the step (S10) may be a sheet for forming a functional layer. In this case, step (S20) may be performed by laminating the plurality of functional layer-forming sheets on a third stack formed by stacking a plurality of fuel electrode-forming sheets manufactured using a tape casting method.

The thickness of each functional layer-forming sheet may be 5 to 100 mu m. When the thickness of each of the functional layer forming sheets is within the above range, the fuel gas can be smoothly transmitted through the functional layer forming sheet while the specific surface area of the functional layer forming sheet is sufficiently large.

A fuel cell can be manufactured by sequentially bonding a buffer layer and an air electrode to an anode-supported electrolyte membrane manufactured by the above method. The buffer layer may be bonded by applying a material for forming a buffer layer to the anode-supported electrolyte membrane by a screen printing method, and then firing the resultant material. Here, the firing may be performed at a temperature of 1,300 to 1,450 ° C. The air electrode may be bonded by applying a material for forming an air electrode to the buffer layer by a screen printing method, and then firing the resultant material. Here, the firing may be performed at a temperature of 1,300 to 1,450 ° C.

The buffer layer-forming material may include gadolinium-doped ceria.

The material for forming the air electrode is preferably a lanthanide metal oxide having a perovskite type crystal structure such as lanthanum-strontium-manganese oxide (LSM) or lanthanum-strontium-cobalt-iron oxide (LSCF), barium- strontium- (BSCF), barium-based metal oxides having a perovskite type crystal structure, or a combination thereof.

On the other hand, the buffer layer is formed by preparing a slurry of a material for forming a buffer layer, preparing a plurality of sheets for buffer layer formation by tape casting using the slurry, stacking the sheets on the anode-supported electrolyte membrane , Or by further firing the resultant. The air electrode may be manufactured by preparing a slurry of a material for forming an air electrode, preparing a plurality of sheets for air electrode formation by tape casting using the slurry, stacking the sheets on the buffer layer, Or may be bonded by further firing. On the other hand, after the above-described sheets for forming a fuel electrode, a sheet for forming a functional layer, a sheet for forming an electrolyte layer, a sheet for forming a buffer layer and a sheet for forming an air electrode were produced, these sheets were laminated in order, Thereby manufacturing a fuel cell.

Hereinafter, the present invention will be described with reference to the following examples, but the present invention is not limited thereto.

Example

Manufacturing example  One: NiO / ScSZ  Synthesis of nanocomposites

60 g of Ni (NO ₃ ) ₂ .6H ₂ O was dispersed in 150 ml of distilled water to obtain a first mixture. Then, 25 g of citric acid was added to the first mixture, followed by heating and stirring at 60 DEG C for 1 hour to obtain a second mixture containing Ni-organic complex. Next, 50 ml of ethylene glycol was added to the second mixture, followed by heating and stirring at 90 캜 for 1 hour to carry out the esterification reaction, thereby obtaining a third mixture containing the Ni-containing polymer. Then, 40 g of ScSZ powder (K-ceracell, particle size: 0.3 탆) was added to the third mixture to obtain a fourth mixture. Subsequently, the fourth mixture was heated and stirred at 180 캜 for 4 hours to evaporate the liquid to obtain a solid. The solids were then calcined at 600 ° C for 1 hour and then milled in ethanol for 3 hours. As a result, a NiO / ScSZ nanocomposite having a NiO nanoparticle of 30 nm, a ScSZ particle of 0.3 m and a BET specific surface area of 14.75 m ² / g was obtained.

Manufacturing example  2: NiO - YSZ / ScSZ  Synthesis of nanocomposites

60 g of Ni (NO ₃ ) ₂ .6H ₂ O, ₂ g of ZrO (NO ₃ ) ₂ .xH ₂ O (x = 2) and 0.45 g of Y (NO ₃ ) ₃ .6H ₂ O were dispersed in 150 ml of distilled water, A mixture was obtained. Thereafter, 10 g of citric acid was added to the first mixture, followed by heating and stirring at 60 ° C for 1 hour to obtain a second mixture containing Ni-organic complex. Next, 25 ml of ethylene glycol was added to the second mixture, followed by heating and stirring at 90 캜 for 1 hour to carry out the esterification reaction, thereby obtaining a third mixture containing the Ni-containing polymer. Then, 10 g of ScSZ powder (K-ceracell, particle size: 0.3 mu m) was added to the third mixture to obtain a fourth mixture. Subsequently, the fourth mixture was heated and stirred at 180 캜 for 4 hours to evaporate the liquid to obtain a solid. The solids were then calcined at 600 ° C for 1 hour and then milled in ethanol for 3 hours. As a result, a NiO-YSZ / ScSZ nanocomposite having a 40 nm NiO nanoparticle, a 30 nm YSZ nanoparticle, a 0.3 μm ScSZ particle and a BET specific surface area of 13 m ² / g was obtained.

Example  1 to 6 and Comparative Example  1 ~ 2: Manufacture of fuel cell

(Production of slurry for forming anode, functional layer and electrolyte layer)

A slurry for forming an anode, a functional layer and an electrolyte layer having the composition shown in Table 1 below was prepared. Each of the slurries was charged with a solid material (ceramic powder and optionally carbon black), toluene, ethanol, and a dispersant into a ball mill containing zirconia balls, ball milled for 24 hours, and then a binder was further added to the ball mill. Ball milling.

A NiO-YSZ slurry and a NiO-YSZ / ScSZ slurry were prepared as the anode slurry. The NiO-YSZ slurry was prepared by mixing 59.12 g of NiO (JTBaker, particle size: 2.1 탆), YSZ (FYT13.0-010H, United Ceramics, particle size: 1.8 Mu m) and 15.44 g of YSZ (TZ-8Y, Toshio, particle size: 0.2 mu m). The NiO-YSZ / ScSZ slurry was prepared by using the NiO-YSZ / ScSZ nanocomposite prepared in Preparation Example 2 as a ceramic powder in the preparation of slurry for fuel electrode formation shown in Table 1 below.

A NiO / ScSZ slurry and a NiO-YSZ / ScSZ slurry were prepared as the functional layer-forming slurry. The NiO / ScSZ slurry used in the preparation of the functional layer-forming slurry shown in the following Table 1 was the NiO / ScSZ nanocomposite prepared in Preparation Example 1. The NiO-YSZ / ScSZ slurry was a ceramic powder used in the preparation of the functional layer-forming slurry shown in Table 1, and the NiO-YSZ / ScSZ nanocomposite prepared in Preparation Example 2 was used.

A YSZ slurry and a ScSZ slurry were prepared as the slurry for forming the electrolyte layer. The YSZ slurry used was YSZ (TZ-8Y, Toshio, particle size: 0.2 mu m) as a ceramic powder in the preparation of the slurry for electrolyte layer formation shown in Table 1 below. The ScSZ slurry used was ScSZ (K-ceracell, particle size: 0.3 mu m) as a ceramic powder in the preparation of the slurry for electrolyte layer formation shown in Table 1 below.

Type of slurry Slurry for fuel electrode formation Slurry for functional layer formation Slurry for electrolyte layer formation The ceramic powder (g) 90 100 100 Carbon black (g) 10 0 0 Toluene (g) 40.52 60.8 50 Ethanol (g) 10.13 15.2 12.5 Dispersant ^{* 1} (g) 2 3.46 1.65 Binder ^{* 2} (g) 43 43 40

* 1: Dispersant (M1201, Ferro, USA)

* 2: Binder (B74001, Ferro, USA)

(Production of sheet for forming anode, functional layer and electrolyte layer)

Each of the slurries was poured into a tape casting apparatus (TAPE CASTING MACHINE STC-14A, Hansung system INC. Korea). Thereafter, the height of the blade attached to the apparatus was adjusted, and the moving speed of the polyethylene film as the base tape was adjusted to 2 cm per second to form a sheet for forming the fuel electrode having a thickness of 100 탆, 10 탆 and 7 탆, Thereby preparing a sheet and a sheet for forming an electrolyte layer.

(Lamination)

Each of the above sheets was cut into a square shape having a size of 10 cm x 10 cm to prepare a sheet for forming a fuel electrode having a thickness of 100 mu m, two sheets for forming a functional layer having a thickness of 10 mu m, and one sheet for forming an electrolyte layer having a thickness of 7 mu m Respectively. Each sheet was then laminated in the order of a sheet for forming a fuel electrode, a sheet for forming a functional layer, and a sheet for forming an electrolyte layer in this order, and then heat-treated at 70 ° C under a pressure of 3,500 psi using a hot pressing machine (Nikkiso, Japan) Lt; / RTI > for 30 minutes. As a result, a laminate in which a fuel electrode, a functional layer and an electrolyte layer were laminated in order was obtained. Here, the fuel electrode and the functional layer were formed by laminating the fuel electrode-forming sheet and the functional layer-forming sheet, respectively, according to the method shown in Fig. 3A.

(Burn-out)

In order to completely oxidize and decompose organic substances and carbon black in the laminate, the laminate was heat-treated in air according to the heat treatment schedule of FIG.

(Co-firing)

After the burn-out, the laminate was heated to 1,400 占 폚 at a heating rate of 5 占 폚 / min, held at 1,400 占 폚 for 3 hours, and then cooled to room temperature (25 占 폚) at a cooling rate of 5 占 min Co-firing was carried out under a pressure of 11.3 g / cm ² according to the heat treatment schedule. In order to minimize warpage of the laminate during burn-out and co-firing, a porous zirconia setter was used as a setter serving as a presser in consideration of reactivity with the laminate. As a result, eight anode-supported electrolyte membranes having the structures shown in Table 2 below were obtained.

Anode Functional layer Electrolyte layer Example 1 NiO-YSZ NiO / ScSZ YSZ Example 2 NiO-YSZ NiO-YSZ / ScSZ YSZ Example 3 NiO-YSZ / ScSZ - YSZ Example 4 NiO-YSZ NiO / ScSZ ScSZ Example 5 NiO-YSZ NiO-YSZ / ScSZ ScSZ Example 6 NiO-YSZ / ScSZ - ScSZ Comparative Example 1 NiO-YSZ - YSZ Comparative Example 2 NiO-YSZ - ScSZ

(Buffer layer and air electrode coupling)

After the co-firing of 20㎛ buffer sheet thickness by using a screen print plating on said laminate _{(Gd 0 .2 Ce 0 .8 O} 2) and a cathode sheet (Ba _{0 .5 0 .5} Sr thickness of 30㎛ Co _{0 .2} Fe _{0 .8} O ₃ and La _0.6 Sr _0.4 Co to _0.2 Fe _0.8 O ₃ 1: a sheet formed by mixing in a weight ratio of 1) were laminated in turn. Thereafter, the resultant was fired at 900 DEG C for 1 hour to obtain a fuel cell.

Evaluation example

Evaluation example  One: Anode  Comparison of physical properties

(NiO-YSZ / ScSZ) prepared in the same manner as in Examples 3 and 6 and the anode (NiO-YSZ / ScSZ) prepared in the same manner as in Examples 1-2, 4-5, ), The porosity, the mechanical strength and the electrical conductivity were evaluated by the following methods, and the results are shown in Table 3 below.

(Measurement of linear shrinkage rate)

Bar specimens were prepared from each of the fuel electrodes before co-firing, and then the lengths of the specimens before and after co-firing were measured directly with a burner caliper to calculate the linear shrinkage ratio according to the following equation (1).

[Equation 1]

(%) = (Specimen length before co-firing - specimen length after co-firing) / (specimen length before co-firing) * 100

(Measurement of porosity)

The porosity was measured by mercury porosimeter using mercury porosimeter equipment to obtain mercury penetration into the pores (see AB Abell, KL Wills, DA Lange, "Mercury Intrusion Porosimetry and Image Analysis of Cement-Based Materials," Journal of Colloid and Interface Science 211: 39-44).

(Measurement of mechanical strength)

The respective fuel electrodes were reduced to convert NiO contained in each of them into Ni, and the mechanical strength of each of the reduced fuel electrodes was measured. The mechanical strength was measured by three-point flexural strength using Instron, and the method was in compliance with KSL-1591.

(Measurement of electric conductivity)

Each of the fuel electrodes was reduced to convert NiO contained therein into Ni, and the electrical conductivity of each of the reduced fuel electrodes was measured according to the 4 point DC measurement method (Van der Pauw, LJ , "A method of measuring specific resistivity and Hall coefficient on lamellae of arbitrary shape", Philips Technical Review 20: 220-224).

Type of anode NiO-YSZ / ScSZ NiO-YSZ Line Shrinkage (%) 29 22 Porosity (%) 50 45 Mechanical strength (MPa) 95 54 Electrical Conductivity (S / cm) 1,400 1,350

Referring to Table 3, it was found that the anode (NiO-YSZ / ScSZ) exhibited excellent linear shrinkage, porosity, mechanical strength and electrical conductivity as compared with the anode (NiO-YSZ). (NiO-YSZ / ScSZ) and the electrolyte layer (NiO-YSZ / ScSZ) because the electrolyte layer made of ScSZ has a linear shrinkage ratio of 28% and is very similar to the line shrinkage ratio of 29% ScSZ), warping and peeling can be suppressed during co-firing.

Evaluation example  2: Anode  Durability comparison

(NiO-YSZ / ScSZ) prepared in the same manner as in Examples 3 and 6 and the anode (NiO-YSZ / ScSZ) prepared in the same manner as in Examples 1-2, 4-5, ), The change of maximum grain size, microstructure and electrical conductivity of Ni particles were evaluated. The heat cycle is performed by heating each of the fuel electrodes at a heating rate of 5 DEG C / min from room temperature (25 DEG C) to 800 DEG C and then cooling the mixture at 800 DEG C to room temperature (25 DEG C) at a cooling rate of 5 DEG C / This is referred to as one cycle).

Fig. 6 shows changes in the maximum particle diameter of the Ni particles of each of the fuel electrodes according to the heat cycle recovery. Here, the Ni particles are referred to not only as Ni particles but also NiO particles. Referring to FIG. 6, the maximum particle diameter of the Ni particles is maintained substantially constant according to the recovery of the heat cycle of the fuel electrode (NiO-YSZ / ScSZ). On the other hand, Of the total population. The increase in the maximum particle diameter of the Ni particles according to the heat cycle recovery means that cohesion occurs between the Ni particles.

7A and 7B show changes in the microstructure of each of the fuel electrodes according to the number of heat cycles (0, 5, and 10 times). FIG. 7A shows the microstructure change of the fuel electrode (NiO-YSZ / ScSZ) according to the heat cycle recovery, and FIG. 7B shows the microstructure change of the fuel electrode (NiO-YSZ) according to the heat cycle recovery. Referring to FIGS. 7A and 7B, NiO-YSZ / ScSZ exhibits little change in microstructure due to heat cycle recovery, while NiO-YSZ has a large number of Ni particles aggregated due to heat cycle recovery The microstructural change was large.

The change in the electrical conductivity of each of the fuel electrodes according to the recovery of the heat cycle is shown in Fig. 8, the electric conductivity of the fuel electrode (NiO-YSZ / ScSZ) is maintained almost constant according to the recovery of the heat cycle, whereas the electric conductivity of the fuel electrode (NiO-YSZ) . The decrease in the electrical conductivity according to the heat cycle recovery means that the cohesion between the Ni particles occurs and the connectivity between the Ni particles decreases.

Evaluation example  3: Anode  Support type Electrolyte membrane  Flatness comparison

The height deviations of the anode-supported electrolyte membranes prepared in Examples 1 to 6 and Comparative Examples 1 and 2 were measured with a simple flatness measuring apparatus (543-250, MITUTOYO, Japan), and the results are shown in Table 4 . Here, the smaller the height deviation is, the better the flatness is. 9A and 9B show changes in height according to the positions of the upper surface and the lower surface of the anode-supported electrolyte membrane produced in Examples 1 and 6. As shown in FIG.

Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Comparative Example 1 Comparative Example 2 Height deviation 42 탆
/ 5cm 55 탆
/ 5cm 65 탆
/ 5cm 48 탆
/ 5cm 41 탆
/ 5cm 19 탆
/ 5cm 110 탆
/ 5cm 215 탆
/ 5cm

Referring to Table 4, the anode-supported electrolyte membranes prepared in Examples 1 to 6 have superior flatness compared to the anode-supported electrolyte membranes prepared in Comparative Examples 1 and 2.

Evaluation example  4: Anode  Support type Electrolyte membrane  Comparison of mechanical strength

The mechanical strengths of the anode-supported electrolyte membranes prepared in Examples 1 to 6 and Comparative Examples 1 and 2 were measured, and the results are shown in Table 5 below. The method for measuring the mechanical strength of the anode-supported electrolyte membrane was the same as the method for measuring the mechanical strength of the anode described in Evaluation Example 1. [

Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Comparative Example 1 Comparative Example 2 Mechanical strength
(MPa) 83 85 96 81 86 112 70 69

Referring to Table 5, the anode-supported electrolyte membranes prepared in Examples 1 to 6 have excellent mechanical strengths as compared with the anode-supported electrolyte membranes prepared in Comparative Examples 1 and 2.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, . Accordingly, the scope of protection of the present invention should be determined by the appended claims.

10: fuel electrode 20: functional layer
30: electrolyte layer 41, 42: setter

Claims (21)

Wherein the nanocomposite comprises Scandium Stabilized Zirconia (ScSZ) particles and Ni-based nanoparticles coated on the surface of the ScSZ particles, the size of the ScSZ particles is 0.2 to 1.0 탆, the Ni The size of nanoparticles is 10 ~ 100nm. The method according to claim 1,
Wherein the Ni nanoparticles include at least one of Ni nanoparticles and NiO nanoparticles. The method according to claim 1,
Wherein the nanocomposite further comprises YSZ (Yttria Stabilized Zirconia) nanoparticles coated on the surface of the ScSZ grains. The method according to claim 1,
Wherein the nanocomposite has a BET specific surface area of 10 to 20 m ² / g. Wherein the nanocomposite comprises Scandium Stabilized Zirconia (ScSZ) particles and Ni nanoparticles coated on the surface of the ScSZ particles. 6. The method of claim 5,
Wherein the nanocomposite further comprises YSZ (Yttria Stabilized Zirconia) nanoparticles coated on the surface of the ScSZ particles. 6. The method of claim 5,
An electrolyte membrane supporting a fuel electrode, comprising: a fuel electrode; and an electrolyte layer disposed on the fuel electrode. 8. The method of claim 7,
Wherein the nanocomposite is contained in the fuel electrode. 8. The method of claim 7,
Wherein the thickness of the fuel electrode is 100 to 1,000 占 퐉, and the thickness of the electrolyte layer is 5 to 10 占 퐉. 8. The method of claim 7,
Further comprising a functional layer disposed between the fuel electrode and the electrolyte layer, wherein the nanocomposite is contained in the functional layer. 11. A fuel cell comprising an anode-supported electrolyte membrane according to any one of claims 5 to 10. (S10) producing a plurality of sheets having casting direction lines by using a tape casting method; And
(S20) of laminating the plurality of sheets in order so that the casting direction lines of the respective sheets cross each other to obtain a first laminate,
Wherein the sheet comprises a nanocomposite, wherein the nanocomposite comprises ScSZ (Scandia Stabilized Zirconia) particles and Ni nanoparticles coated on the surface of the ScSZ particles. 13. The method of claim 12,
Wherein the nanocomposite further comprises YSZ (Yttria Stabilized Zirconia) nanoparticles coated on the surface of the ScSZ particles. 13. The method of claim 12,
Wherein the plurality of sheets are sequentially stacked such that the casting direction lines are perpendicular to each other in a clockwise direction or a counterclockwise direction along the thickness direction of the first stacked body in the step (S20). 13. The method of claim 12,
Wherein the sheet is a sheet for forming a fuel electrode, and after the step (S20)
(S30) of obtaining a second laminate including the first laminate by laminating sheets for forming an electrolyte layer on the first laminate using a tape casting method; And
(S40) simultaneously firing the second stacked body. 16. The method of claim 15,
Wherein each of the fuel electrode-forming sheets has a thickness of 25 to 100 占 퐉. 16. The method of claim 15,
Wherein the step (S40) is performed while applying a pressure of 5 to 15 g / cm < ² > on the second laminate. 16. The method of claim 15,
Wherein the step (S40) is performed at a temperature of 1,300 ~ 1,450 ° C. 13. The method of claim 12,
Wherein the sheet is a sheet for forming a functional layer, and the step (S20) is a step of forming a sheet for forming a plurality of functional layers on a third stacked body produced by stacking a plurality of sheets for fuel electrode formation, Wherein the electrolyte membrane is formed by laminating. 20. The method of claim 19,
Wherein the thickness of each of the functional layer-forming sheets is 5 to 100 占 퐉. 13. The method of claim 12,
The tape casting method of step S10 is carried out using a slurry,
Mixing toluene and alcohol in a ratio of 4: 1 by weight to obtain a liquid medium;
20 to 200 parts by weight of the nanocomposite and 10 to 50 parts by weight of a pore former are added to and mixed with 100 parts by weight of the liquid medium to obtain a first mixture;
Adding and mixing a binder to the first mixture in an amount of 40 to 50 parts by weight based on 100 parts by weight of the sum of the nanocomposite and the pore-forming agent to obtain a second mixture; And
And adding a dispersant to the second mixture in an amount of 1 to 5 parts by weight based on 100 parts by weight of the sum of the nanocomposite and the pore-forming agent to obtain a third mixture.

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