KR101902617B1 - Solid Oxide Electrochemical Device having Triple Layer Perovskite for Air-Electrode Catalyst - Google Patents

Abstract

An electrochemical device is provided. The electrochemical device includes a fuel electrode, an air electrode containing a triple layer perovskite cathode catalyst having a composition represented by the following formula (1), and a solid oxide electrolyte layer disposed therebetween.
[Chemical Formula 1]
(Ln _3-a1-a2 X ¹ X ² _{a1 a2) d} (M _{3 ^1-bc} M ² _b M ³ _{c) e} O _f
In Formula 1, Ln may be a lanthanide element, X ¹ and X ² may be different metals selected from the group consisting of Mg, Ca, Sr, and Ba, and M ¹ , M ² , and M ³ May be different metals selected from the group consisting of Ti, V, Cr, Mn, Fe, Co, Ni, Cu and Zn, and a1 and a2 may be 0 or more D is a value between 0.9 and 1, e is a value between 0.9 and 1, f is between 7.5 and 9.5, and b + c is a positive value with a condition satisfying 0 & .

Description

TECHNICAL FIELD [0001] The present invention relates to a solid oxide electrochemical device having a triple-layered perovskite cathode catalyst,

The present invention relates to an electrochemical device, and more particularly, to an electrochemical device having an air electrode.

The electrochemical device includes an anode, a cathode, and an electrolyte layer between the anode and the cathode. Of these electrochemical devices, the devices that consume or generate air include fuel cells, metal-air cells, and water decomposition devices. Such an electrochemical device has an air electrode that consumes or generates air in the anode and the cathode. The air electrode may use a noble metal catalyst such as platinum, iridium, or ruthenium as a catalyst. However, these noble metal catalysts have been studied for various catalysts to replace them because of the increase in the price of the device and the limited durability.

Perovskite materials are being studied as one of these alternative catalysts. As an example, KR 1334902 discloses the application of a bilayer perovskite material to the cathode of a fuel cell.

SUMMARY OF THE INVENTION The present invention provides a solid oxide electrochemical device having a cathode catalyst having improved oxygen generating characteristics and oxygen reducing characteristics.

The technical objects of the present invention are not limited to the technical matters mentioned above, and other technical subjects not mentioned can be clearly understood by those skilled in the art from the following description.

According to an aspect of the present invention, there is provided an electrochemical device. The electrochemical device includes a fuel electrode, an air electrode containing a triple layer perovskite cathode catalyst having a composition represented by the following formula (1), and a solid oxide electrolyte layer disposed therebetween.

[Chemical Formula 1]

(Ln _3-a1-a2 X ¹ X ² _{a1 a2) d} (M _{3 ^1-bc} M ² _b M ³ _{c) e} O _f

In Formula 1, Ln may be a lanthanide element, X ¹ and X ² may be different metals selected from the group consisting of Mg, Ca, Sr, and Ba, and M ¹ , M ² , and M ³ May be different metals selected from the group consisting of Ti, V, Cr, Mn, Fe, Co, Ni, Cu and Zn, and a1 and a2 may be 0 or more D is a value between 0.9 and 1, e is a value between 0.9 and 1, f is between 7.5 and 9.5, and b + c is a positive value with a condition satisfying 0 & .

The triple layer perovskite cathode catalyst may be represented by the following formula (2).

(2)

Ln _1.5 (X ¹ _a3 X ² _a4 ) _1.5 M ¹ M ² M ³ O _9-δ

In the above formula (2), Ln, X ¹ , X ² , M ¹ , M ² and M ³ are as defined in formula (1), a 3 and a 4 are each a hydrogen atom, Value, and [delta] is from 0 to 1.

The triple layer perovskite cathode catalyst may be represented by the following formula (3).

(3)

Ln _1.5 X ¹ _1.5 CoFeM ³ O _9-隆

In Formula 3, Ln, X ¹ , and M ³ are as defined in Formula (1).

Wherein the triple layer perovskite cathode catalyst comprises at least one of Nd _1.5 Ba _1.5 CoFeMnO _{9- ?} , Nd _1.5 Sr _1.5 CoFeMnO _{9- ?} , Nd _1.5 Ca _1.5 CoFeMnO _{9- ?} , La _1.5 Ba _1.5 CoFeMnO _{9- ?} , Nd _1.5 Ba _1.5 CoFeNiO _9-delta , or Nd _1.5 Ba _1.5 CoFeCuO _9-delta . The triple layer perovskite cathode catalyst may be Nd _1.5 Ba _1.5 CoFeMnO _{9- ?} .

The air electrode may further contain an oxygen ion conductor. The electrolyte layer may contain an oxygen ion conductive metal oxide, a proton conductive metal oxide, or a mixture thereof. The fuel electrode may comprise an ion conductor and a catalytic metal, which are oxygen ion conductors or proton conductors.

According to an aspect of the present invention, there is provided a method of operating an electrochemical device. The operation method includes operating the electrochemical device in a fuel cell mode in which fuel is supplied to the fuel electrode and air is supplied to the air electrode to produce electricity. In addition, the operation method includes operating the electrochemical device in a fuel generation mode in which an electric field is applied between the fuel electrode and the air electrode to produce fuel in the fuel electrode.

1 is a cross-sectional view schematically illustrating an air electrode of an electrochemical device according to an embodiment of the present invention.
2 is a schematic view showing a unit cell of a solid oxide electrochemical device according to an embodiment of the present invention.
FIG. 3 is an X-ray diffraction graph of the perovskite material according to Production Example 1, Comparative Example 1, and Comparative Example 2. FIG.
4 is a graph showing the a-axis length and the c-axis length of perovskite materials according to Production Example 1, Comparative Example 1 and Comparative Example 2, respectively.
5 is a graph showing the oxygen content and B-site oxidation number of the perovskite materials according to Production Example 1, Comparative Example 1 and Comparative Example 2, respectively.
6 is a graph showing the results of X-ray photoelectron spectroscopy performed on the perovskite material according to Production Example 1, Comparative Example 1, and Comparative Example 2.
FIG. 7 is an X-ray diffraction graph of the perovskite material according to Production Examples 1 to 3 and 5 to 6. FIG.
FIG. 8 is a graph showing oxygen generation characteristics (a) and oxygen reduction characteristics (b) for perovskite materials according to Production Example 1, Comparative Example 1, and Comparative Example 2;
9A is an X-ray diffraction chart of the perovskite material according to Production Examples 7 to 10 and Comparative Example 2, FIG. 9B is a graph showing the X-ray diffraction pattern of the perovskite material according to Production Example 1, Production Examples 7 to 10, FIG. 2 is a graph showing oxygen generation characteristics for a perovskite material according to the present invention. FIG.
10 is a graph showing IV (a) and electrochemical impedance (b) characteristics obtained by operating an electrochemical device manufactured according to Production Example 11 in a fuel cell mode.
11 is a graph showing IV characteristics obtained by operating an electrochemical device manufactured according to Production Example 11 in a fuel cell mode and a water decomposition mode.
12 is a graph showing a voltage according to an operation time obtained while the electrochemical device manufactured according to Production Example 11 is operated in a circulating operation mode.
13 is a graph showing IV (a) and electrochemical impedance (b) characteristics obtained by operating an electrochemical device manufactured according to Production Example 12 in a fuel cell mode.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to the embodiments described herein but may be embodied in other forms.

Triple layer perovskite cathode catalyst

In the electrochemical device, the air electrode may be referred to as an oxygen generation and / or an oxygen reduction catalyst, because oxygen generation and / or an oxygen reduction reaction may occur in the air electrode.

The cathode catalyst according to an embodiment of the present invention may have a composition represented by the following formula (1).

[Chemical Formula 1]

(Ln _3-a1-a2 X ¹ X ² _{a1 a2) d} (M _{3 ^1-bc} M ² _b M ³ _{c) e} O _f

In the formula 1, Ln may be a lanthanide element, that is, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb or Lu. In one embodiment, Ln may be La, Nd, Sm, or Gd. More specifically, Ln may be La or Nd.

X ¹ and X ² are alkaline earth metal elements, and may be, for example, different metals selected from the group consisting of Mg, Ca, Sr, and Ba, and specifically may be Ba, Sr, or Ca, respectively.

M ¹ , M ² , and M ³ are transition metal elements, and may be, for example, different metals selected from the group consisting of Ti, V, Cr, Mn, Fe, Co, Ni, Cu and Zn. In one embodiment, M ¹ , M ² , and M ³ may be Co, Fe, Mn, or Ni, respectively.

In the above formula (1), a1 and a2 may be 0 or more in the condition that 0 < a1 + a2 < 3. Specifically, a1 and a2 each satisfy a1 + a2 of 2.5 to 0.5, more specifically, a1 + a2 satisfies 2 to 1. In one example, a1 + a2 satisfies 0 Lt; / RTI &gt;

In Formula 1, b and c may be positive values satisfying 0 < b + c < 3. Specifically, b and c may each have a value between 0.5 and 1.5.

In the above formula (1), d may be a value between 0.9 and 1, and e may be a value between 0.9 and 1. Also, f may be a value between 7.5 and 9.5.

Such perovskite materials can have a layered structure due to the presence of the lanthanum element in the unit crystals and can further have a triple layer. Specifically, such a triple-layered perovskite material is a material in which perovskite layers of three layers are laminated in a unit crystal, and a z-axis (c-axis) length varies depending on the tetragonal system, and about 9 to 12 angstroms, which is about three times the length of the (a and b axes). As the triple layer perovskite material has a layered structure, the movement of oxygen molecules becomes smooth, the ratio of oxygen atoms in the lattice increases, and as a result of the difference in the electronic structure in oxygen atoms, oxygen reduction or oxygen generation Can be improved.

Such a triple layer perovskite material may have a composition represented by the following formula (2). The perovskite material represented by the following formula (2) may correspond to a case where a1 + a2 is 1.5, d is 1, e is 1, b is 1, and c is 1 in the above formula (1).

(2)

Ln _1.5 (X ¹ _a3 X ² _a4 ) _1.5 M ¹ M ² M ³ O _9-δ

In Formula 2, Ln, X ¹ , X ² , M ¹ , M ² , and M ³ are as defined in Formula (1).

In formula (2), a3 and a4 may each be a value between 0 and 1 under the condition that a3 + a4 satisfies 1. may be 0 to 1.

Such a triple layer perovskite material may be represented by the following general formula (3).

(3)

Ln _1.5 X ¹ _1.5 CoFeM ³ O _9-隆

In the above formula (3), Ln, X ¹ , and M ³ may be the same as defined in formula (1), and? May be a positive number of 1 or less. Specifically, the Ln may be a Nd or La, X ¹ may be a Ba, Sr, or Ca, M ³ may be Mn, Ni, or Cu. In particular, X ¹ may be Ba having a small degree of lattice deformation because the difference in atomic radius between the lanthanide element (L) is not large.

Specifically, the triple layer perovskite material may be selected from the group consisting of Nd _1.5 Ba _1.5 CoFeMnO _{9- ?} , Nd _1.5 Sr _1.5 CoFeMnO _{9- ?} , Nd _1.5 Ca _1.5 CoFeMnO _{9- ?} , La _1.5 Ba _1.5 CoFeMnO _{9- ?} , Nd _1.5 Ba _1.5 CoFeNiO _9-delta , or Nd _1.5 Ba _1.5 CoFeCuO _9-delta .

This triple layer perovskite is prepared by mixing precursor powders such as oxides, carbides, halides, carbonates, nitrates, and acetates of each metal component in accordance with the metal element ratio, milling the mixture, and then molding, firing and pulverizing . In addition, the triple layer perovskite material may be chemically synthesized by co-precipitation, hydrothermal synthesis, solution combustion, sol-gel or CVD (chemical vapor deposition); RF-Magnetron Sputter, PVD (Physical Vapor Deposition), APD (Arc Plasma Deposition), or the like.

Cathode of electrochemical device

1 is a cross-sectional view schematically illustrating an air electrode of an electrochemical device according to an embodiment of the present invention. The electrochemical device includes an air electrode or a cathode, a cathode, and an electrolyte layer positioned therebetween. Such an electrochemical device may be a fuel cell, a metal-air cell, a water decomposition device, a gas sensor, or a capacitor.

Referring to FIG. 1, the cathode current collector 150 is a conductor containing a plurality of pores, and may be a metal mesh, a metal foam, or a porous carbon structure. In the case of a metal mesh or a metal foam, it may be made of Ni, Co, Mn, or an alloy thereof, or stainless steel coated on the surface with Ni, Co, Mn, or their respective alloys.

The air electrode catalyst layer 120 may be positioned on the air electrode collector 110. The air electrode catalyst layer 120 may include a triple layer perovskite as described above as a catalyst and a binder. As an example, the air electrode catalyst layer 120 may be formed by coating a slurry obtained by mixing the triple-layered perovskite and a binder on the air electrode current collector 110, followed by heat treatment. The binder may be selected from the group consisting of carbon black (Ketjen Black), PVdF, vinylidene fluoride / hexafluoropropylene copolymer, polyvinylidene fluoride, polyacrylonitrile, polymethyl methacrylate, polytetrafluoroethylene, styrene, And a rubber-based polymer.

Depending on the type of the electrochemical device, the air electrode may be formed by an oxygen reduction reaction (ORR) represented by the following Reaction Scheme 1, an Oxygen Evolution Reaction (OER) represented by the following Reaction Scheme 2, have.

[Reaction Scheme 1]

ORR: 1 / 2O ₂ + H ₂ O + 2e ^- → 2OH ^-

[Reaction Scheme 2]

OER: 2OH ^- ? 1 / 2O ₂ + H ₂ O + 2e ^-

In an air electrode of a fuel cell such as a solid oxide fuel cell, an oxygen reduction reaction may occur. In an air electrode of a metal-air battery, an oxygen reduction reaction may occur when an oxygen generation reaction is discharged during charging. An occurrence reaction may occur.

When the triple layer perovskite material is used in the air electrode catalyst layer 120, the triple layer perovskite material has a layered structure, so that the movement of oxygen molecules is smooth and the oxygen atom ratio in the lattice is increased , The oxygen reduction reaction and the oxygen generation reaction can be promoted as the difference in the electronic structure in the oxygen atom occurs.

Solid oxide electrochemical device

2 is a schematic view showing a unit cell of a solid oxide electrochemical device according to an embodiment of the present invention.

2, the unit cell may include a fuel electrode 200 and an air electrode 100 facing each other, and an electrolyte layer 300 disposed between the fuel electrode 200 and the air electrode 100 . The solid oxide electrochemical device may have a plurality of such unit cells. At this time, the unit cells may be sequentially stacked.

The air electrode 100 may include an air electrode collector 110 and a air electrode catalyst layer 120 having a triple layer perovskite material disposed on the air electrode collector 110, as described with reference to FIG. The air electrode 100 can perform an oxygen reduction reaction as well as an oxygen reduction reaction. The air electrode collector 110 and the air electrode catalyst layer 120 will be described in detail with reference to FIG. However, the air electrode catalyst layer 120 may further include an oxygen ion conductor in addition to the triple layer perovskite material. Oxygen ion conductors are oxygen ion conducting metal oxides, rare-earth-doped ceria (RDC), such as neodymium-doped ceria (NDC), gadolinium-doped ceria (GDC) samarium-doped ceria); _{YSZ (yttria stabilized zirconia, ZrO 2} / Y 2 O 3); _{ScSZ (scandia stabilized zirconia, ZrO 2} / Sc 2 O 3); And strontium- and magnesium-doped lanthanum gallate (LSGM).

The electrolyte layer 300 may be a solid oxide electrolyte layer and may contain the above-described oxygen ion conductor, proton conductor, or a mixture thereof. The proton conductor is a proton conductive metal oxide. Examples of the proton conductive metal oxide include barium zirconate (BaZrO ₃ ), barium cerate (BaCeO ₃ ), barium zirconate cerate BaZr _(1-x) Ce _x O ₃ , 0.05? _X ? 0.95), strontium cerate (SrCeO ₃ ), strontium zirconate (SrZrO ₃ ), and strontium zirconate cerate _(1-x) Ce _x O ₃ , 0.05? _X ? 0.95). The doped trivalent element in the proton conductor may be yttrium (Y), lanthanum (e.g., ytterbium (Yb)), or a combination thereof. As one example, the proton conductor is a yttrium (Y) -doped barium zirconate capable of being operated at a low temperature and exhibiting high efficiency, specifically Ba ₁ Zr _{1 -x} Y _x O ₃ -δ (0.1 _{? X ?} 0.2; (For example, 2.95?? 2.975), or the proton conductor is a barium zirconate cerate co-doped with yttrium (Y) and ytterbium (Yb), specifically Ba ₁ Zr _0.1 Ce _0.7 Y _0.1 Yb _0.1 O _2.95 .

When the electrolyte layer 300 is an oxygen ion conductor layer, the electrochemical device is an oxygen ion conductive electrochemical device. When the electrolyte layer 300 is a proton conductor layer, the electrochemical device is a proton conducting electrochemical device, or When the electrolyte layer 300 is a mixture layer of an oxygen ion conductor and a proton conductor, it may be called a mixed conducting electrochemical device.

The fuel electrode 200 may be an electrode capable of diffusion of fuel and conduction of electrons therein. Fuel can be hydrogen. The fuel electrode 200 may include a fuel electrode current collector 210 and a fuel electrode catalyst layer 220 disposed on the fuel electrode current collector 210. The fuel electrode current collector 210 may be a conductor containing a plurality of pores and may be a metal mesh, a metal foam, or a porous carbon structure. In the case of a metal mesh or a metal foam, it may be made of Ni, Co, Mn, or an alloy thereof, or stainless steel coated on the surface with Ni, Co, Mn, or their respective alloys.

The fuel electrode catalyst layer 220 may include a catalyst metal and an ion conductor, specifically, an oxygen ion conductor or a proton conductor. Further, the fuel electrode catalyst layer 220 may be a cermet of a catalyst metal and an oxygen ion conductor, or a cermet of a catalyst metal and a proton conductor. Lt; / RTI &gt; When the electrolyte layer 300 is an oxygen ion conductor layer, the fuel electrode catalyst layer 220 may have the same or different oxygen ion conductors as the oxygen ion conductors included in the electrolyte layer 300, If the proton conductor layer 300 is a proton conductor layer, the fuel electrode catalyst layer 220 may have the same or different type of proton conductor than the proton conductor included in the electrolyte layer 300. Specific examples of the oxygen ion conductor and the proton conductor are as described above.

The catalytic metal may serve to enhance the electronic conductivity of the fuel electrode catalyst layer 220 and also to generate protons and electrons from the fuel or to promote the generation of fuel from protons and electrons. The catalytic metal may be a transition metal, and may be, for example, Ni, Cu, Pt, Pd, or a combination of two or more thereof.

In addition, the fuel electrode catalyst layer 220 may further contain a carbon material. The fuel electrode catalyst layer 220 may be formed by mixing a catalyst metal oxide with an oxygen ion conductor and further with a carbon precursor, followed by sintering the catalyst precursor. The catalytic metal oxide may be reduced through hydrogen supplied before the electrochemical device is operated, and may be positioned in the fuel electrode catalyst layer 220 as a catalytic metal.

The electrochemical device can operate in a fuel cell mode in which fuel is supplied to the fuel electrode and air is supplied to the air electrode to generate electricity and an electric field is applied between the fuel electrode and the air electrode, The fuel cell can be operated in the fuel generating mode. The fuel generation mode, specifically, the hydrogen generation mode may be referred to as a water decomposition mode or an electrolysis mode.

The proton conductive solid oxide electrochemical device can be operated in a dual mode of a fuel cell mode and a water decomposition mode through the following reaction formula.

Fuel cell mode

Fuel ^{_{electrode: H 2 → 2H + + 2e}} -

Air electrode: 2H ⁺ + 1 / 2O ₂ + 2e ^- → H ₂ O (oxygen reduction reaction)

Water decomposition mode

Fuel electrode: 2H ⁺ + 2e ^- ? H ₂

Air electrode: H ₂ O → 2H ⁺ + 1 / 2O ₂ + 2e ^- (oxygen generation reaction)

The oxygen ion conductive solid oxide electrochemical device can be operated in a dual mode of a fuel cell mode and a water decomposition mode through the following reaction formula.

Fuel cell mode

Fuel electrode: H ₂ + O ^2- ? H ₂ O + 2e ^-

Air electrode: 1 / 2O ₂ + 2e ^- → O ^2- (oxygen reduction reaction)

Water decomposition mode

Fuel electrode: H ₂ O + 2e ^- → H ₂ + O ^2-

Air electrode: O ^2- → 1 / 2O ₂ + 2e ^- (oxygen generating reaction)

As described above, the solid oxide fuel cell according to the present embodiment performs both the fuel cell mode in which the oxygen reduction reaction takes place and the water decomposition mode or the electrolysis mode in which the oxygen generation reaction occurs, as the triple layer perovskite is contained in the air electrode . In other words, unlike conventional electrochemical devices, the solid oxide fuel cell according to the present embodiment is excellent in that two functions can be realized by one cell.

For example, the fuel cell may be operated in the fuel cell mode to produce electricity when the power consumption is high, and the fuel cell may be operated in the water decomposition mode to produce fuel in the nighttime when the power consumption is low .

Hereinafter, exemplary embodiments of the present invention will be described in order to facilitate understanding of the present invention. It should be understood, however, that the following examples are for the purpose of promoting understanding of the present invention and are not intended to limit the scope of the present invention.

Production Example 1: Nd _1.5 Ba _1.5 CoFeMnO _9-隆>

(NO ₃ ) ₂ .6H ₂ O (0.01 mol), Ba (NO ₃ ) ₂ (0.01 mol), Co (NO ₃ ) ₂ .6H ₂ O (0.0067 mol), Fe (0.0067 mol) of Mn (NO ₃ ) ₃ .9H ₂ O and 0.002 mol of Mn (NO ₃ ) ₂ .H ₂ O and 0.02 mol of glycine as a fuel were dissolved in distilled water, The mixture was heated on a hot plate with stirring to evaporate the water to cause auto-ignition. The resultant ash was first calcined at 600 ° C for 4 hours. Thereafter, the mixture was ball-milled with ethanol using a zirconia ball for 24 hours, dried, and calcined at 900 DEG C for 4 hours to obtain a material.

Production Example 2: Nd _1.5 Sr _1.5 CoFeMnO _9-隆>

_{Nd (NO 3) 2 · 6H} 2 O (0.01 _{mole), Sr (NO 3) 2} (0.01 _{mole), Co (NO 3) 2} · 6H 2 O (0.0067 _{mol), Fe (NO 3) 3} · 9H 2 O (0.0067 mol), and Mn (NO ₃ ) ₂ .H ₂ O (0.0067 mol) were used in place of the metal precursors.

Production Example 3: Nd _1.5 Ca _1.5 CoFeMnO _9-隆>

_{Nd (NO 3) 2 · 6H} 2 O (0.01 _{mol), Ca (NO 3) 2} · 4H 2 O (0.01 _{mole), Co (NO 3) 2} · 6H 2 O (0.0067 mol), Fe (NO _{3) 3} · 9H ₂ O (0.0067 mol), and Mn (NO _{3) 2} ·, except that metal precursor of H ₂ O (0.0067 mol) was synthesized material using the same method as in Production example 1.

&Lt; Preparation Example 4: La _1.5 Ba _1.5 CoFeMnO _9-隆>

_{La (NO 3) 2 · 6H} 2 O (0.01 _{moles), Ba (NO 3) 2} (0.01 _{mole), Co (NO 3) 2} · 6H 2 O (0.0067 _{mol), Fe (NO 3) 3} · 9H 2 O (0.0067 mol), and Mn (NO ₃ ) ₂ .H ₂ O (0.0067 mol) were used in place of the metal precursors.

Production Example 5: Nd _1.5 Ba _1.5 CoFeNiO _9-隆>

_{Nd (NO 3) 2 · 6H} 2 O (0.01 _{moles), Ba (NO 3) 2} (0.01 _{mole), Co (NO 3) 2} · 6H 2 O (0.0067 _{mol), Fe (NO 3) 3} · 9H 2 O (0.0067 mol), and Ni (NO ₃ ) ₂ .6H ₂ O (0.0067 mol) were used in place of the metal precursors.

&Lt; Preparation Example 6: Nd _1.5 Ba _1.5 CoFeCuO _9-隆>

_{Nd (NO 3) 2 · 6H} 2 O (0.01 _{moles), Ba (NO 3) 2} (0.01 _{mole), Co (NO 3) 2} · 6H 2 O (0.0067 _{mol), Fe (NO 3) 3} · 9H 2 O (0.0067 mol), and Cu (NO ₃ ) ₂揃 2.5H ₂ O (0.0067 mol) were used in place of the metal precursors.

Production Example 7: Nd ₂ BaCo ₃ O _9-隆>

Except using the metal precursors of Nd (NO ₃ ) ₂揃 6H ₂ O (0.013 mol), Ba (NO ₃ ) ₂ (0.0067 mol), and Co (NO ₃ ) ₂揃 6H ₂ O The material was synthesized in the same manner as in Production Example 1.

Production Example 8: Nd ₂ BaCo ₂ FeO _9-隆>

_{Nd (NO 3) 2 · 6H} 2 O (0.013 _{moles), Ba (NO 3) 2} (0.0067 _{mol), Co (NO 3) 2} · 6H 2 O (0.013 mol), and Fe (NO _{3) 3} · 9H ₂ O (0.0067 moles) of metal precursors were used to synthesize the material.

Production Example 9: NdBa ₂ Co ₃ O _9-隆>

Except using the metal precursors of Nd (NO ₃ ) ₂揃 6H ₂ O (0.0067 mol), Ba (NO ₃ ) ₂ (0.013 mol), and Co (NO ₃ ) ₂揃 6H ₂ O The material was synthesized in the same manner as in Production Example 1.

Production Example 10: NdBa ₂ Co ₂ FeO _9-隆>

_{Nd (NO 3) 2 · 6H} 2 O (0.0067 _{moles), Ba (NO 3) 2} (0.013 _{mole), Co (NO 3) 2} · 6H 2 O (0.013 mol), and Fe (NO _{3) 3} · 9H ₂ O (0.0067 moles) of metal precursors were used to synthesize the material.

&Lt; Comparative Example 1: Ba _0.5 Sr _0.5 Co _0.8 Fe _0.2 O _3-隆 >

Ba (NO _{3) 2} (0.0125 _{mol), Sr (NO 3) 2} (0.0125 _{mol), Co (NO 3) 2} · 6H 2 O (0.01 mol), and _{Fe (NO 3) 3 · 9H} 2 O (0.005 Moles) of the metal precursors were used in place of the metal precursors of Preparation Example 1.

Comparative Example 2: Nd (Ba _0.5 Sr _0.5 ) Co _1.5 Fe _0.5 O _6-隆 >

_{Nd (NO 3) 2 · 6H} 2 O (0.0067 _{moles), Ba (NO 3) 2} (0.0033 _{mol), Sr (NO 3) 2} (0.0033 _{mol), Co (NO 3) 2} · 6H 2 O (0.02 mol ), And Fe (NO ₃ ) ₃ .9H ₂ O (0.0033 mol) were used in place of the metal precursors of Preparation Example 1.

FIG. 3 is an X-ray diffraction graph of the perovskite material according to Production Example 1, Comparative Example 1, and Comparative Example 2. FIG.

3, the single layer perovskite material according to Comparative Example 1 exhibits a cubic structure, while the double layer perovskite material according to Comparative Example 2 and the triple layer perovskite material according to Production Example 1 It can be seen that the skate material exhibits a tetragonal structure.

4 is a graph showing the a-axis length and the c-axis length of perovskite materials according to Production Example 1, Comparative Example 1 and Comparative Example 2, respectively. In this case, the a-axis length and the c-axis length are values calculated by using the Bragg's law (n? = 2d sin?) Of the X-ray diffraction values in FIG.

Referring to FIG. 4, the perovskite material according to Comparative Example 1, the perovskite material according to Comparative Example 2, and the perovskite material according to Preparation Example 1 have an a-axis length of about 3.8-4 angstroms or a Axis grating constant value. On the other hand, in the case of the c-axis length or the c-axis lattice constant value, the perovskite material according to Comparative Example 1 was about 3.99 Å (a: c≈1: 1), and the perovskite material according to Comparative Example 2 was about And a perovskite material according to Production Example 1 is about 11.64 Å (a: c ≒ 1: 3). From this, it can be seen that the perovskite material according to Comparative Example 1 is a single layer perovskite material, the perovskite material according to Comparative Example 2 is a double layer perovskite material, It can be said that the skate material is confirmed to be a triple layer perovskite material.

5 is a graph showing the oxygen content and B-site oxidation number of the perovskite materials according to Production Example 1, Comparative Example 1 and Comparative Example 2, respectively. At this time, the oxygen content and the B site oxidation number were obtained using a chemical titration experiment.

Referring to FIG. 5, in the perovskite material according to Comparative Example 1,? Is about 0.264 in Ba _0.5 Sr _0.5 Co _0.8 Fe _0.2 O _3- ?, the average oxidation number of B site metal, that is, Co and Fe is about Δ is about 0.392 in the perovskite material of Nd (Ba _0.5 Sr _0.5 ) Co _1.5 Fe _0.5 O _6-δ according to Comparative Example 2, and the average of the B sites, ie, Co and Fe The oxidation number was about 3.112, and in the perovskite material according to Production Example 1, i.e., Nd _1.5 Ba _1.5 CoFeMnO _9- ?, The delta was about 0.444 and the average of the B sites, i.e., Co, Fe, and Mn The oxidation number was found to be about 3.277.

Thus, the perovskite material according to Preparation Example 1 showed higher oxygen deficiency (?) Than the perovskite material according to Comparative Examples 1 and 2.

6 is a graph showing the results of X-ray photoelectron spectroscopy performed on the perovskite material according to Production Example 1, Comparative Example 1, and Comparative Example 2.

Referring to Figure 6, (a) is associated as oxygen XPS spectrum, peaks are ^2- O oxygen in the lattice, and OH ^- is an oxygen peak E is low. It is O ^2- that plays a leading role in the oxygen generation reaction. On the other hand, the content of oxygen vacancies can be known from the area of OH ^- peaks, and it can be seen that the triple-layer perovskite according to Production Example 1 has the largest oxygen vacancy content.

(b), (c) and (d) are XPS spectra related to Co, Fe and Nd, respectively. It can be seen that the B site elements Co and Fe represent polyvalent elements. From this, it can be seen that oxygen vacancies are formed in the perovskite material as described above with reference to FIG.

FIG. 7 is an X-ray diffraction graph of the perovskite material according to Production Examples 1 to 3 and 5 to 6. FIG.

Referring to FIG. 7, it can be seen that the perovskite materials according to Production Examples 1 to 3 and 5 to 6 exhibit a tetragonal structure as a whole (a, b).

When the material of the X ¹ in the formula (3) reducing the ionic radius position as Ba, Sr, Ca (Production Example 1, preparation 2, preparation 3), the position of the X- ray diffraction chart can be seen that movement to its respective have. As can be seen from the Bragg rule, this is seen as a result of the reduction of the interplanar distance in the lattice as the ion radius decreases (a).

On the other hand, even if the M ³ -valent material of Formula 3 is changed to Mn, Ni and Cu (Production Example 1, Production Example 5, Production Example 6), there is no significant difference (a).

FIG. 8 is a graph showing oxygen generation characteristics (a) and oxygen reduction characteristics (b) for perovskite materials according to Production Example 1, Comparative Example 1, and Comparative Example 2;

In order to investigate oxygen generation characteristics and oxygen reduction characteristics, a three electrode system was prepared. Specifically, 10 mg of the substance according to the above experimental examples, 5 mg of carbon black (Vulcan X-72, Cabot), 750 uL of distilled water, 250 uL of isopropyl alcohol and 16 uL of Nafion solution (Sigma-Aldrich) The ink was dispersed by ultrasonic dispersion for a minute. 3 uL of this ink was dropped on a RDE (Rotating Disk Electrode) tip and dried to prepare a half-cell, that is, a working electrode. The working electrode, the counter electrode, the platinum wire, and the reference electrode, Hg / HgO, were immersed in a 0.1 M KOH solution to form a three-electrode system.

In the case of the oxygen generating reaction, pre-treatment was carried out using a cyclic voltammetry method to activate the materials according to the above experimental examples. The range was 0.05V to 1.2V (vs. RHE) and the speed was 100mV / s. The pretreatment was repeated 50 times and the oxygen generation characteristics were evaluated by proceeding once at a rate of 5 mV / s in the range of 1.2 to 1.7 V (vs. RHE).

The oxygen reduction reaction was catalyzed by the cyclic voltammetry as in the oxygen generation reaction. The range was from 0.05V to 1.2V (vs. RHE) and the speed was 100mV / s. The pretreatment was repeated 50 times, and the oxygen reduction characteristics were analyzed by advancing the range of 1.1 V to 0.2 V at a rate of 5 mV / s. At this time, oxygen was continuously supplied to the electrolytic solution to keep the oxygen saturation, and the characteristics were evaluated while rotating the working electrode at 400, 900, 1600, and 2500 rpm.

Referring to FIG. 8, the oxygen generation characteristics (a) of the triple layer perovskite material according to Production Example 1, as compared to the single layer perovskite material according to Comparative Example 1 and the double layer perovskite material according to Comparative Example 2 ) And oxygen reduction characteristics (b) were both excellent. This is presumably due to the increase in the ratio of the lattice structure to the lattice oxygen atom and the difference in the electron structure in the oxygen atom due to the addition of the lanthanide element.

9A is an X-ray diffraction chart of the perovskite material according to Production Examples 7 to 10 and Comparative Example 2, FIG. 9B is a graph showing the X-ray diffraction pattern of the perovskite material according to Production Example 1, Production Examples 7 to 10, FIG. 2 is a graph showing oxygen generation characteristics for a perovskite material according to the present invention. FIG.

Referring to FIG. 9A, it can be seen that the perovskite materials according to Production Examples 7 to 10, especially the materials according to Production Example 9 and Production Example 10, do not form a single phase uniformly depending on the composition

9B, the perovskite materials according to Production Examples 7 to 10 are similar to the double layer perovskite materials according to Comparative Example 2 (Production Example 8 and Production Example 10) or lower (Production Example 7 and Production Example 9). On the other hand, the perovskite material according to Preparation Example 1 was formed into a single phase of a triple layer perovskite (FIG. 3), and oxygen generation characteristics were superior to double layer perovskite materials (FIG. 5A).

From these results, it is found that when the ratio of the lanthanide metal and the alkaline earth metal is 1.5: 1.5, it is advantageous to form a triple-layered perovskite structure and excellent oxygen generating property.

PREPARATION EXAMPLE 11 Proton Conducting Solid Oxide Electrochemical Device [

65 wt% NiO and a proton conductor, 35 wt% Ba ₁ Zr _0.1 Ce _0.7 Y _0.1 Yb _0.1 O _3-δ , a binder and a plasticizer were mechanically mixed to prepare a round fuel electrode having a diameter of 25 mm and a thickness of 1 mm And pre-sintering was performed at 900 ° C. A slurry of Ba ₁ Zr _0.1 Ce _0.7 Y _0.1 Yb _0.1 O _3-δ , which is a prepared proton conductor, was coated on one side of the fuel electrode three times and co-fired at 1450 ° C for 4 hours to form a diameter A half-cell having a thickness of 20 mm and a thickness of 0.75 mm was produced. The air electrode was prepared by weighing Nd _1.5 Ba _1.5 CoFeMnO _9-δ , which is a triple-layered perovskite material according to Production Example 1, and NDC in a mass ratio of 1: 1, followed by alpha-terpineol, Di-n butyl phthalate, and polyvinyl butyral, and then coated on the electrolyte of the half-cell (reaction area: 0.2827 cm ² ). Thereafter, a button-shaped unit device was completed through heat treatment at 950 ° C for 2 hours.

PREPARATION EXAMPLE 12 Oxygen Ion Conducting Solid Oxide Electrochemical Device [

A mixture of 65 wt% NiO and 35 wt% NDC (neodymium-doped ceria, Nd _0.1 Ce _0.9 O _2-δ ), a binder and a plasticizer were mechanically mixed to form a circular shape with a diameter of 25 mm and a thickness of 1 mm And pre-sintering was performed at 900 占 폚. A pre-prepared oxygen ion conductive NDC electrolyte slurry was coated on one side of the fuel electrode three times and co-fired at 1550 占 폚 for 4 hours to produce a 20 mm diameter, 0.75 mm thick half-cell. The air electrode was prepared by weighing Nd _1.5 Ba _1.5 CoFeMnO _9-δ , which is a triple-layered perovskite material according to Production Example 1, and NDC in a mass ratio of 1: 1, followed by alpha-terpineol, Di-n butyl phthalate, and polyvinyl butyral, and then coated on the electrolyte of the half-cell (reaction area: 0.2827 cm ² ). Thereafter, a button-shaped unit device was completed through heat treatment at 950 ° C for 2 hours.

<Operation example: Operation of solid oxide electrochemical device>

The unit devices prepared in Production Example 11 or 12 were placed in a reactor and closed with a sealing agent to maintain the oxygen partial pressure difference between the fuel electrode and the air electrode.

The fuel cell mode operation was performed under the conditions of supplying hydrogen at a flow rate of 200 sccm to the fuel electrode at an operating temperature of 650 ° C and air at a flow rate of 200 sccm to the air electrode.

The water decomposition mode operation was performed under the condition that hydrogen was supplied at a flow rate of 25 sccm to the fuel electrode at an operating temperature of 650 ° C, and air humidified to the air electrode was supplied at a flow rate of 200 sccm.

In addition, in the circulation operation mode, the fuel cell mode operation was performed for about 20 hours, and then the water decomposition mode operation was performed for about 2 hours.

10 is a graph showing I-V (a) and electrochemical impedance (b) characteristics obtained by operating an electrochemical device manufactured according to Production Example 11 in a fuel cell mode.

Referring to FIG. 10, the maximum output density was about 560 mWcm ^-2 , which is higher than that of the conventional proton conductive fuel cell. This is because the triple layer perovskite used in the air electrode has a large amount of oxygen deficiency, so that the movement of oxygen molecules is smooth and the electrochemical characteristics are improved.

11 is a graph showing I-V characteristics obtained by operating an electrochemical device manufactured according to Production Example 11 in a fuel cell mode and a water decomposition mode.

Referring to FIG. 11, the electrochemical device according to the present experimental example includes both a fuel cell mode in which an oxygen reduction reaction occurs in the air electrode and a water decomposition mode, that is, an electrolysis mode in which an oxygen generation reaction occurs Can be performed.

12 is a graph showing a voltage according to an operation time obtained while the electrochemical device manufactured according to Production Example 11 is operated in a circulating operation mode.

Referring to FIG. 12, the electrochemical device manufactured according to Production Example 11 operated in a fuel cell mode at about 0.8 V and operated in a water decomposition mode at about 1.2 V. On the other hand, since the conventional water decomposition apparatus is operated in a relatively harsh environment such as to maintain a high water vapor partial pressure (P _H2O ) to supply water molecules and to operate at a relatively high potential (V), deterioration easily occurs It was difficult to apply a single perovskite. However, it can be seen that the electrochemical device manufactured according to Production Example 11 to which the triple perovskite material is applied shows a more stable behavior even in the operation of repeating the fuel cell mode and the water decomposition mode for about 100 hours.

13 is a graph showing I-V (a) and electrochemical impedance (b) characteristics obtained by operating an electrochemical device manufactured according to Production Example 12 in a fuel cell mode.

Referring to FIG. 13, the maximum power density was as high as about 1200 mWcm ^-2 . This is because the triple layer perovskite used in the air electrode has a large amount of oxygen deficiency, so that the movement of the oxygen molecules is smooth and the electrochemical characteristics are greatly improved.

10 and 12, it can be seen that the triple layer perovskite can be applied to both the proton conductive solid oxide electrochemical device and the oxygen ion conductive solid oxide electrochemical device.

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 exemplary embodiments, but, on the contrary, This is possible.

Claims (9)

Fuel electrode;
An air electrode containing a triple layer perovskite cathode catalyst having a composition represented by the following formula (1); And
An electrochemical device comprising a solid oxide electrolyte layer disposed therebetween:
[Chemical Formula 1]
(Ln _3-a1-a2 X ¹ X ² _{a1 a2) d} (M _{3 ^1-bc} M ² _b M ³ _{c) e} O _f
In Formula 1,
Ln is a lanthanide element,
X ¹ and X ² are different metals selected from the group consisting of Mg, Ca, Sr, and Ba,
M ¹ , M ² and M ³ are different metals selected from the group consisting of Ti, V, Cr, Mn, Fe, Co, Ni,
each of a1 and a2 is a value of 0 or more under the condition that 0.5? a1 + a2? 2.5,
Each of b and c is a positive value in a condition satisfying 0 < b + c < 3,
d is a value between 0.9 and 1,
e is a value between 0.9 and 1,
f is a value between 7.5 and 9.5. The method according to claim 1,
Wherein d is 1, the sum of a1 and a2 is 1.5, e is 1, b is 1, and c is 1, the triple-layered perovskite cathode catalyst is represented by the following Chemical Formula 2 :
(2)
Ln _1.5 (X ¹ _a3 X ² _a4 ) _1.5 M ¹ M ² M ³ O _9-δ
In Formula 2, Ln, X ¹ , X ² , M ¹ , M ² , and M ³ are as defined in Formula 1,
each of a3 and a4 is a value between 0 and 1 under the condition satisfying a3 + a4 = 1,
9-delta is the same as f in formula (1), and delta is 0 to 1. 3. The method of claim 2,
Wherein a3 is 1 and a4 is 0 in Formula 2, the triple-layered perovskite cathode catalyst is represented by Formula 3:
(3)
Ln _1.5 X ¹ _1.5 CoFeM ³ O _9-隆
In Formula 3, Ln, X ¹ , and M ³ are as defined in Formula (1). The method of claim 3,
Wherein the triple layer perovskite cathode catalyst comprises at least one of Nd _1.5 Ba _1.5 CoFeMnO _{9- ?} , Nd _1.5 Sr _1.5 CoFeMnO _{9- ?} , Nd _1.5 Ca _1.5 CoFeMnO _{9- ?} , La _1.5 Ba _1.5 CoFeMnO _{9- ?} , Nd _1.5 Ba _1.5 CoFeNiO _9-delta , or Nd _1.5 Ba _1.5 CoFeCuO _9-delta . 5. The method of claim 4,
Wherein the triple layer perovskite cathode catalyst is Nd _1.5 Ba _1.5 CoFeMnO ₉ -δ. The method according to claim 1,
Wherein the air electrode further contains an oxygen ion conductor. The method according to claim 1,
Wherein the electrolyte layer contains an oxygen ion conductive metal oxide, a proton conductive metal oxide, or a mixture thereof. The method according to claim 1,
Wherein the fuel electrode comprises an ionic conductor, which is an oxygen ion conductor or a proton conductor, and a catalytic metal. Providing an electrochemical device comprising a fuel electrode, an air electrode containing a triple-layered perovskite cathode catalyst having a composition represented by Formula 1, and a solid oxide electrolyte layer disposed therebetween;
Operating the electrochemical device in a fuel cell mode in which fuel is supplied to the fuel electrode and air is supplied to the air electrode to produce electricity; And
And operating the electrochemical device in a fuel generating mode for producing fuel in the fuel electrode by applying an electric field between the fuel electrode and the air electrode.
[Chemical Formula 1]
(Ln _3-a1-a2 X ¹ X ² _{a1 a2) d} (M _{3 ^1-bc} M ² _b M ³ _{c) e} O _f
In Formula 1,
Ln is a lanthanide element,
X ¹ and X ² are different metals selected from the group consisting of Mg, Ca, Sr, and Ba,
M ¹ , M ² and M ³ are different metals selected from the group consisting of Ti, V, Cr, Mn, Fe, Co, Ni,
each of a1 and a2 is a value of 0 or more under the condition that 0.5? a1 + a2? 2.5,
Each of b and c is a positive value in a condition satisfying 0 < b + c < 3,
d is a value between 0.9 and 1,
e is a value between 0.9 and 1,
f is a value between 7.5 and 9.5.

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