KR101642427B1 - Method for manufacturing anode material for solid oxide fuel cell - Google Patents

Abstract

The present invention provides an anode material having excellent thermal and chemical stability and high electric conductivity. An anode material according to an embodiment of the present invention includes a compound of RET _2-x T ' _x O _{5 + ?} . Wherein R comprises one or more elements selected from rare earth or lanthanide groups, wherein E and E 'comprise different elements selected from the group of the alkaline earth metals, and T is one or more elements selected from transition metals O is oxygen, x is a number of more than 0 and less than 1, and? Is a positive number of 0 or 1 or less, which is a value that makes the compound of the formula (1) electrically neutral.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an anode material for a solid oxide fuel cell,

The present invention relates to a solid oxide fuel cell, and more particularly, to a solid oxide fuel cell using an oxide having an perovskite-related structure as an anode.

A solid oxide fuel cell (SOFC) is a highly efficient, environmentally friendly electrochemical power generation technology that directly converts the chemical energy of a fuel gas into electrical energy. Since all components are solid, SOFC has a simple structure, relatively low cost, and is free from electrolyte loss and replacement and corrosion problems compared to other fuel cells. Solid oxide fuel cells can also use relatively high impurity fuels and have many advantages such as hybrid power generation capability and high efficiency. In addition, hydrocarbon fuel can be directly used without reforming the fuel into hydrogen, leading to simplification of the fuel cell system and reduction of production cost.

The SOFC includes an anode (anode or anode, cathode) in which a fuel such as hydrogen or a hydrocarbon is oxidized, a cathode (cathode or cathode, anode) where oxygen gas is reduced to oxygen ion (O ^2- ) A solid electrolyte, and specific physical properties are required depending on the type of material used.

As the anode electrode, a nickel-based material is mainly used. Nickel is a very good conversion catalyst and has excellent advantages such as excellent electroconductivity as an electrocatalyst and helping the electrochemical oxidation of hydrogen. Nickel-cermet, which is currently used mainly, is inexpensive and stable in a reducing atmosphere of high temperature. Ni-YSZ is most widely studied due to its thermal expansion coefficient similar to that of Yttria-stabilized zirconia (YSZ) and its low charge transfer resistance at the Ni-YSZ interface.

On the other hand, nickel-cermet has a low resistance to carbon (C) and sulfur (S) contained in hydrocarbon-based fuels. Direct oxidation of hydrocarbons and carbon monoxide without the supply of steam to the dry fuel gas and without the application of a sufficiently high current density results in the formation of anodic materials by carbon deposition because nickel has the catalytic properties of forming carbon- There is a problem in that it is destroyed rapidly. Nickel is an excellent electrochemical catalyst for the electrochemical oxidation of hydrogen. However, when natural gas or hydrocarbon is directly used as a fuel, its activity is lowered by carbon deposition. When carbon is deposited on nickel particles, activation polarization ) Becomes very high, and the anode performance is deteriorated. In addition, it is very important that the structure phase should be stable in a hydrogen environment, and at the same time, it is necessary to maintain an electric conductivity higher than a certain value. In such a hydrogen environment, there is a fear that the performance of the anode may deteriorate during long-term use. Therefore, an anode material having excellent thermal and chemical stability and high electrical conductivity is required.

Korea Patent Publication No. 2011-0106341

A technical object of the present invention is to provide an anode material having excellent thermal and chemical stability and high electric conductivity.

Another object of the present invention is to provide a solid oxide fuel cell including an anode made of the anode material.

According to an aspect of the present invention, there is provided an anode material for a solid oxide fuel cell, comprising:

≪ Formula 1 >

RET _2-x T ' _x O _{5 +?}

In Formula 1, R may include one or more elements selected from a rare earth group or a lanthanide group, and E may include one or more elements selected from an alkaline earth metal group, and T and T 'May comprise different elements selected from transition metals, O is oxygen, x is a number of more than 0 and less than 1, and said delta is a positive number of 0 or 1 or less, .

In one embodiment of the present invention, the R is at least one selected from the group consisting of Y, Sc, Sm, Gd, Nd, Pr, Gd), europium (Eu), terbium (Tb), erbium (Er), or mixtures thereof.

In one embodiment of the present invention, E may include barium Ba.

In one embodiment of the present invention, T and T 'may include manganese (Mn) or cobalt (Co).

In one embodiment of the present invention, the T 'may substitute the T to occupy the position of T in the compound of formula (1).

In one embodiment of the present invention, the RET _2-x T ' _x O _{5 +?} Compound of Formula 1 may have a bilayer perovskite structure.

In one embodiment of the present invention, the RET _2-x T ' _x O _{5 + δ} compound of Formula 1 may include a compound of Formula 2 below.

(2)

_{PrBaMn 2-x T 'x O} 5 + δ

Wherein T 'is one or more elements selected from transition metals, O is oxygen, x is a number of more than 0 and less than 1, and? Is a positive number of 0 or 1 or less, The compound of Formula 2 is a value that is electrically neutral.

In order to accomplish the above object, the anode material for a solid oxide fuel cell according to the technical idea of the present invention includes a compound of the following formula (3).

(3)

PrBaMn _2-x Co _x O _{5 +?}

In the formula (3), O is oxygen, x is a number of more than 0 and less than 1, and? Is a positive number of 0 or 1 or less.

In one embodiment of the present invention, the PrBaMn _2-x Co _x O _{5 + delta} compound of Formula 3 may include a compound having x in the range of 0.2 to 0.4.

In one embodiment of the present invention, the PrBaMn _2-x Co _x O _{5 + delta} compound of Formula 3 is PrBaMn _1.8 Co _0.2 O _{5 + delta} compound, PrBaMn _1.7 Co _0.3 O _{5 + delta} compound, or PrBaMn _1.6 Co _0.4 O _{5 +?} Compound.

According to an aspect of the present invention, there is provided a solid oxide fuel cell including: an anode including the anode material; A cathode disposed facing the anode; And an electrolyte disposed between the anode and the cathode.

In one embodiment of the present invention, the electrolyte is selected from the group consisting of yttria stabilized zirconia (YSZ), scandia stabilized zirconia (ScSZ), samaria doped ceria (SDC), gadolinia doped ceria (GDC) And mixtures thereof.

The anode material according to the technical idea of the present invention includes a compound having a novel double layer perovskite structure.

In the examples of the present invention, the electrical conductivity at a high temperature, particularly at 800 ° C, was high and the maximum power density was high. In addition, excellent thermal and chemical stability at high temperatures can be provided.

Further, when nickel is used as an anode material and a hydrocarbon-based fuel is used as a fuel according to the prior art, resistance to carbon (C) and sulfur (S) contained in the fuel is low. However, PBMCO according to the technical idea of the present invention can solve problems such as carbon deposition of nickel.

The effects of the present invention described above are exemplarily described, and the scope of the present invention is not limited by these effects.

1 is a schematic view showing a solid oxide fuel cell according to an embodiment of the present invention.
2 is a schematic view showing a double layer perovskite structure constituting an anode material according to an embodiment of the present invention.
3 is a graph showing an X-ray diffraction pattern of an anode material of PBMCO prepared according to an embodiment of the present invention.
4 is a graph showing the electrical conductivity of an anode of PBMCO prepared according to an embodiment of the present invention at 5% H ₂ .
FIG. 5 is a graph showing the Nyquist plot showing the frequency spectrum of the impedance according to the cobalt content at 800 ° C. when hydrogen is used as fuel for the anode of the PBMCO prepared according to the embodiment of the present invention.
FIG. 6 is a graph showing the IV polarization curve and the maximum power density of the fuel cell according to the content of cobalt at 800 ° C. when hydrogen is used as a fuel for a solid oxide fuel cell including an anode of PBMCO prepared according to an embodiment of the present invention. It is a graph.
7 is a graph showing a result of measuring the stability of a solid oxide fuel cell with respect to a PBMCO anode manufactured according to an embodiment of the present invention.

Hereinafter, the present invention will be described in more detail. In interpreting the terms or words used in the present specification and claims, it is to be understood that the interpretation of terms or words used herein is necessarily conventional, based on the principle that the inventor can properly define the concept of the term to describe its invention in the best way It is to be understood that the invention is not to be interpreted as being limited only by the precautionary sense, but should be construed in accordance with the meaning and concept consistent with the technical idea of the present invention as described in the present specification.

1 is a schematic view of a solid oxide fuel cell 100 according to an embodiment of the present invention.

Referring to Figure 1, a solid oxide fuel cell 100 includes an anode 110, a cathode 120 disposed opposite the anode 110, and a cathode 120 disposed between the anode 110 and the cathode 120, And an electrolyte 130 which is a solid oxide. And optionally a buffer layer 140 disposed between the anode 110 and the electrolyte 130.

The electrochemical reaction of the solid oxide fuel cell 100 can be performed by an anode reaction in which the oxygen gas O ₂ of the cathode 120 is changed to oxygen ions O ^2- and the anode reaction of the anode 110 in the form of H ₂ or hydrocarbons ) And oxygen ions that have moved through the electrolyte.

<Reaction Scheme>

Anode reaction: 1/2 O ₂ + 2e ^- -> O ^2-

Cathode reaction: H ₂ + O ^2- -> H ₂ O + 2e ^-

In the cathode 120 of the solid oxide fuel cell 100, the oxygen adsorbed on the surface of the electrode is dissociated and diffused to form a triple phase boundary where the electrolyte 130, the cathode 120, and the pores (not shown) The oxygen ions are converted into oxygen ions, and the generated oxygen ions are transferred to the anode 110, which is a fuel electrode, through the electrolyte 130.

In the anode 110 of the solid oxide fuel cell 100, the moved oxygen ions combine with the hydrogen contained in the fuel to generate water. At this time, hydrogen evolves electrons to hydrogen ions (H ⁺ ) and binds to the oxygen ions. The discharged electrons move to the cathode 120 through wiring (not shown) to change oxygen to oxygen ions. Through such electron transfer, the solid oxide fuel cell 100 can perform the battery function.

The technical idea of the present invention relates to a material constituting the anode 110 of the solid oxide fuel cell 100. [ The material constituting the anode 110 will be described in detail below.

The cathode 120 is not particularly limited and a known cathode may be used. The cathode 120 may include, for example, LaSrFe-YSZ, and may include, for example, La _0.8 Sr _0.2 Fe-YSZ. The cathode 120 may comprise, for example, NBSCF50-GDC (NdBa _0.5 Sr _0.8 Co _1.8 Fe _0.8 O _{5 +?} -Ce _0.9 Gd _0.1 O ₂ -δ).

The electrolyte 130 is not particularly limited as long as it can be generally used in the art. For example, the electrolyte 130 may be a stabilized zirconia based system such as yttria stabilized zirconia (YSZ) and scandia stabilized zirconia (ScSZ); Ceria systems doped with rare earth elements such as samaria-doped ceria (SDC), gadolinia-doped ceria (GDC) and the like; Other LSGM ((La, Sr) (Ga, Mg) O ₃ ) system; And the like. In addition, the electrolyte 130 may include strontium or magnesium-doped lanthanum gallate. For example, the electrolyte 130 may include La _0.9 Sr _0.1 Ga _0.8 Mg _0.2 O _{3 -δ} .

The buffer layer 140 may be positioned between the anode 110 and the electrolyte 130 to provide a smooth contact. The buffer layer 140 may function to mitigate the crystal lattice distortion of the anode 110 and the electrolyte 130, for example. The buffer layer 140 may include, for example, LDC (La _0.4 Ce _0.6 O _{2 -δ} ). The buffer layer 140 may be omitted as an optional component.

Since the solid oxide fuel cell 100 can be manufactured by a conventional method known in the art, a detailed description thereof will be omitted here. In addition, the solid oxide fuel cell 100 may be applied to various structures such as a tubular stack, a flat tubular stack, a planar type stack, and the like.

The solid oxide fuel cell 100 may be in the form of a stack of unit cells. For example, a unit cell (MEA, membrane and electrode assembly) composed of an anode 110, a cathode 120, and an electrolyte 130 is stacked in series, and a separator plate a stack of unit cells can be obtained with a separator interposed therebetween.

Hereinafter, the anode 110 will be described in detail.

The anode 110 according to the technical idea of the present invention has a double layered perovskite crystal structure.

A simple perovskite structure may have the formula ABO ₃ . In the single perovskite structure, elements having relatively large ionic radii may be located in the A-site at the corner of the cubic lattice, and the number of coordination numbers (CN , Coordination number). For example, a rare earth element, an alkaline rare earth element, and an alkaline element may be located in the A-site. The B-site, which is the body center of the cubic lattice, may contain elements having relatively small ionic radii, and may have six coordination numbers by oxygen ions. For example, cobalt (Co), iron (Fe), and the like and a transition metal may be located in the B-site. Oxygen ions may be located at each face center of the cubic lattice. Such a single perovskite structure can generally result in structural displacements when other materials are substituted on the A-site, and it is often the case that the nearest oxygen ions in the octahedron of BO ₆ consisting of six) it may cause structural variations.

2 is a schematic view showing a double layer perovskite structure constituting an anode material according to an embodiment of the present invention.

Referring to FIG. 2, the bilayer perovskite structure is a crystal lattice structure in which two or more elements are regularly arranged on the A-site, and may have a formula of AA'B ₂ O _{5 + delta} . Specifically, a lanthanide compound having a bilayer perovskite structure can be basically repeated with the lamination permutation of [BO ₂ ] - [AO] - [BO ₂ ] - [A'O] along the c axis. For example, B may be manganese (Mn), and A may be a lanthanide group including yttrium (Y) or praseodymium (Pr), and A 'may be barium (Ba).

Upon reduction in a hydrogen atmosphere, the anode material changes from a simple perovskite structure to a double perovskite structure. Such a double perovskite structure can accelerate oxygen ion movement and improve thermal and chemical stability. In addition, an anode having higher electrical conductivity in a hydrogen atmosphere and thermo-chemical stability than the conventional anode and exhibiting excellent performance can be realized.

The anode according to one embodiment of the present invention may include a compound represented by the following formula (1).

&Lt; Formula 1 >

RET _2-x T ' _x O _{5 +?}

In Formula 1, R may include one or more elements selected from a rare earth group or a lanthanide group, and E may include one or more elements selected from an alkaline earth metal group, and T and T 'May comprise different elements selected from transition metals, O is oxygen, x is a number of more than 0 and less than 1, and said delta is a positive number of 0 or 1 or less, .

The R may comprise one or more elements selected from rare earth metals and may include, for example, yttrium (Y), scandium (Sc), samarium (Sm), gadolinium (Gd) .

The R may include one or more elements selected from the group consisting of lanthanides, such as neodymium (Nd), praseodymium (Pr), samarium (Sm), gadolinium (Gd), europium (Eu) Tb), erbium (Er), or mixtures thereof.

The E may include one or more elements selected from the group of the alkaline earth metals, and may include, for example, barium Ba.

The T and T 'may comprise one or more elements selected from transition metals and may include, for example, manganese (Mn) or cobalt (Co). The T 'may be an element that substitutes the T to occupy the position of T in the compound of Formula 1. The substitution may increase the thermal stability and chemical stability of the anode.

O is oxygen. Is a positive number of 1 or less, and the value of the compound of the formula (1) is an electrical neutrality. The above 隆 represents interstitial oxygen in the following double layer perovskite structure and the value of 隆 can be determined according to a specific crystal structure.

The anode according to an embodiment of the present invention may include a compound represented by the following formula (2).

(2)

_{PrBaMn 2-x T 'x O} 5 + δ

In Formula 2, T 'may include one or more elements selected from transition metals, and may include, for example, cobalt (Co). O is oxygen, x is a number of more than 0 and less than 1, and? Is a positive number of 0 or 1 or less.

The anode according to an embodiment of the present invention may include a compound represented by the following formula (3).

(3)

PrBaMn _2-x Co _x O _{5 +?}

In the formula (3), O is oxygen, x is a number of more than 0 and less than 1, and? Is a positive number of 0 or 1 or less.

The PrBaMn _2-x Co _x O _{5 + delta} compound of Formula 3 may include a compound having x in the range of 0.2 to 0.4. For example, the PrBaMn _2-x Co _x O _{5 + delta} compound of Formula 3 may be PrBaMn _1.8 Co _0.2 O _{5 + delta} compound, PrBaMn _1.7 Co _0.3 O _{5 + delta} compound, or PrBaMn _1.6 Co _0.4 O _{5 +} &Lt; / RTI &gt; compounds.

Hereinafter, a method for manufacturing an anode material for a solid oxide fuel cell according to the technical idea of the present invention will be described.

The method for producing the anode material includes the steps of mixing each of the metal precursors metered in accordance with the composition of the RET _2-x T ' _x O _{5 + δ} compound of Formula 1 (for example, wet using a solvent) (Wet) mixture, firing the solid material in air to obtain a fired product, and polishing the fired product.

The metal precursor is mixed in a stoichiometric ratio to obtain the compound of the above formula. Examples of the metal precursor include, but are not limited to, nitrides, oxides, halides and the like of R, E, T, T 'and the like constituting each of the anode materials of the above chemical formula. For example, when the compound forming the anode is PrBaMn _2-x Co _x O _{5 +?} Compound of formula (3), for example, the compound forming the anode is PrBaMn _1.8 Co _0.2 O _{5 +?} Compound, PrBaMn _1.7 Co _0.3 O _{5 +?} Compound, or PrBaMn _1.6 Co _0.4 O _{5 +?} Compound, and the metal precursor may be a nitride, an oxide, a halide, or the like containing at least one of Pr, Ba, Mn and Co.

In the step of mixing the metal precursor with the solvent, water may be used as a solvent, but the present invention is not limited thereto. The metal precursor can be used without limitation as long as it can dissolve the metal precursor. For example, a lower alcohol having 5 or less carbon atoms, such as methanol, ethanol, 1-propanol, 2-propanol and butanol; Acidic solutions such as nitric acid, hydrochloric acid, sulfuric acid, and citric acid; water; Organic solvents such as toluene, benzene, acetone, diethyl ether and ethylene glycol; May be used alone or in combination.

The step of mixing the metal precursor with the solvent may be performed at a temperature in the range of about 100 ° C to about 200 ° C and may be carried out for a predetermined time under agitation so that each component can be thoroughly mixed. The mixing process, removing the solvent, and addition of additives required for this purpose are well known, for example, by the pechini method, and therefore are not described here.

After the mixing process, ultrafine solid material can be obtained by spontaneous combustion. The ultrafine solid can then be heat treated (calcined, sintered) for a time period ranging from about 400 ° C. to about 950 ° C. for a time period ranging from about 1 hour to about 5 hours, for example, at about 600 ° C. for about 4 hours.

If necessary, a second heat treatment (calcination, sintering) may be performed after the firing. This second heat treatment step is a step of calcining in air for about 12 hours at a temperature in the range of about 950 ° C to about 1500 ° C, for a period of about 1 hour to about 24 hours, for example, at a temperature in the range of about 950 to about 1500 ° C To obtain a powdery product.

Then, the fired product may be ground or pulverized to obtain a fine powder having a predetermined size. For example, milling and mixing by ball milling in acetone for about 24 hours. Next, the mixed powder is put into a metal mold and pressed, and then the pressurized pellet is sintered in the atmosphere to produce an anode material. Sintering may be performed at a temperature in the range of about 950 ° C to about 1500 ° C for a period ranging from about 12 hours to about 24 hours, for example, at a temperature in the range of from about 950 to about 1500 ° C for a period of about 24 hours, . The fired product may be ground or pulverized to obtain a fine powder having a predetermined size.

An anode can be prepared from the composition for an anode. For example, the anode can be formed by coating a composition for the anode-forming material on a substrate and then performing heat treatment.

The thickness of the anode can typically range from about 1 [mu] m to about 100 [mu] m in a solid oxide fuel cell. For example, the thickness of the anode may range from about 5 [mu] m to about 50 [mu] m.

[Example]

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The above embodiments are not intended to limit the scope of the present invention.

Among the compounds of RET _2-x T ' _x O _{5 +?} Of the above formula 1, PrBaMn _1.8 Co _0.2 O _{5 +}隆 compound, PrBaMn _1.7 Co _0.3 O _{5 +}隆 compound, or PrBaMn _1.6 Co _0.4 O _{5 +} Was selected as the anode material. Hereinafter the PrBaMn _1.8 Co _0.2 O _{5 + δ} compound, PrBaMn _1.7 Co _0.3 O _{5 + δ} compound, or PrBaMn _1.6 Co _0.4 O to referred to as "PBMCO" a _{5 + δ} compound as a whole, and individually PrBaMn _1.8 Co _0.2 O _{5 + δ} compound is _{"PBMCO2", PrBaMn 1.7 Co 0.3} O 5 + δ compound is _{"PBMCO3", PrBaMn 1.6 Co 0.4} O 5 + δ compound will be referred to as "PBMCO4".

To form the PBMCO, the corresponding metal precursors were dissolved in a solvent mixed with ethylene glycol, citric acid, and distilled water. After melting, ultrafine solid can be obtained through self-combustion process. The ultrafine solid was heat-treated at 600 ° C. for 4 hours, pulverized and mixed in a ball mill for 24 hours in acetone, dried, compressed with pellets at 5 MPa and air-dried at 1500 ° C. for 24 hours Lt; / RTI &gt; The PBMCO anode material was formed after reduction in an atmosphere of 100% H ₂ (corresponding to 3% H ₂ O) to form a bilayer perovskite structure. The anode material was mixed with an organic binder (Heraeus V006) to synthesize an anode slurry.

The full single cell was compacted with pellets of LSGM powder and sintered in air at about 1475 ° C for 5 hours and polished to obtain a dense electrolyte with a thickness of about 250 μm. Next, a cathode slurry containing NdBa _0.5 Sr _0.8 Co _1.8 Fe _0.8 O _{5 +?} -Ce _0.9 Gd _0.1 O ₂ -δ, a buffer layer slurry containing La _0.4 Ce _0.6 O ₂ -δ (LDC), and PrBaMn ₂ after _{-x Co x O 5 + δ (PBMCO} ) printing each screen on the electrolyte of the anode slurry comprising, by sintering at about about 950 ℃ for 4 hours in air to prepare a fuel cell.

The thicknesses of the anode, cathode, and electrolyte formed as described above were about 50 mu m, about 50 mu m, and about 250 mu m, respectively, and silver wire was attached to the cathode and anode using silver paste for current collection. In addition, 15 wt% of Co-Fe catalyst was added to the PBMCO anode to demonstrate the catalytic effect.

According to the above manufacturing method, a solid oxide fuel cell composed of a PBMCO anode, an LDC buffer layer, an LSGM electrolyte, and an NBSCF-GDC cathode was fabricated.

3 is a graph showing an X-ray diffraction pattern of an anode material of PBMCO prepared according to an embodiment of the present invention. This X-ray diffraction was measured by Cu Kα radiation powder dispersion method using a diffractometer of Rigaku Corporation, Japan.

Referring to FIG. 3, the PBMCO anode material was sintered in the air, exposed to 97% H ₂ , and then showed a bilayer perovskite structure. These double layer perovskite structures were all found when the content of cobalt (Co) in PBMCO compounds was 0.2, 0.3, and 0.4.

4 is a graph showing the electrical conductivity of an anode of PBMCO prepared according to an embodiment of the present invention at 5% H ₂ .

The electrical conductivity was measured by four terminal DC arrangement in an atmosphere of 5% H ₂ (the rest being N ₂ ). A silver wire was used as a probe of the four terminals. The current and the voltage were measured using BioLogic's constant potential device at intervals of about 50 DEG C in a measurement interval of about 100 DEG C to about 800 DEG C. [

Referring to FIG. 4, the electrical conductivity of the anode of PBMCO according to an embodiment of the present invention tends to increase with increasing temperature (i.e., moving to the left). The increasing tendency of the electrical conductivity to this temperature was the same when the content of cobalt (Co) in the PBMCO compound was 0.2, 0.3, and 0.4.

Table 1 is a table showing the electric conductivity (s / cm) according to the temperature derived from Fig.

PBMCO type Cobalt content
(x value) density Electrical conductivity
(700 ° C) Electrical conductivity
(800 ° C) PBMCO2 0.2 70% 0.98 1.6 PBMCO3 0.3 70% 0.92 1.5 PBMCO4 0.4 63% 0.39 0.67

Referring to Table 1, as the content of cobalt in the PBMCO compound increases, the electrical conductivity tends to decrease somewhat. In particular, the content of cobalt in the PBMCO compound showed the highest electrical conductivity at x = 0.2 at 700 ℃ and 800 ℃. It is known that as the content of cobalt in the PBMCO compound increases, the electrical conductivity decreases as the content of cobalt increases in a hydrogen atmosphere. This result corresponds to this.

The measured conductivity of the anode of PBMCO was 0.98 s / cm at 700 ° C and 1.6 s / cm at 800 ° C for x = 0.2 (ie PrBaMn _1.8 Co _0.2 O _{5 + δ} ). As a comparative example, the measured electrical conductivity of the anode formed using La _0.75 Sr _0.25 Cr _0.5 Mn _0.5 O _{5 + delta} was 0.54 s / cm at 750 ° C and 1.5 s / cm at 850 ° C. Therefore, the electric conductivity of the anode of PBMCO according to the embodiment of the present invention is higher than that of the comparative example.

FIG. 5 is a graph showing the Nyquist plot showing the frequency spectrum of the impedance according to the cobalt content at 800 ° C. when hydrogen is used as fuel for the anode of the PBMCO prepared according to the embodiment of the present invention.

Referring to FIG. 5, ohmic resistance, non-ohmic resistance, and total resistivity can be obtained, which are summarized in Table 2. In Table 2, the unit of ohmic resistivity, non-ohmic resistivity, and total resistivity is ohm cm ^-2 .

PBMCO type Cobalt content
(x value) OCV
(V) Ohmic resistivity Non-ohmic resistivity Total resistivity PBMCO2 0.2 1.094 0.1655 0.3878 0.5533 PBMCO3 0.3 1.071 0.1302 0.1040 0.2342 PBMCO4 0.4 1.09 0.1751 0.0920 0.2671

Referring to Table 2, the non-ohmic resistivity tends to decrease as the content of cobalt in the PBMCO compound increases. On the other hand, the ohmic resistivity showed no tendency to increase or decrease with the content of cobalt, and showed the lowest value at x = 0.3.

FIG. 6 is a graph showing the IV polarization curve and the maximum power density of the fuel cell according to the content of cobalt at 800 ° C. when hydrogen is used as a fuel for a solid oxide fuel cell including an anode of PBMCO prepared according to an embodiment of the present invention. It is a graph.

In FIG. 6, the solid symbols represent the voltage according to the current density, and the open symbols represent the power density according to the current density.

The I-V polarization curves of FIG. 6 were measured at 800 DEG C using a constant potential device from BioLogic. Specifically, the I-V polarization curves used humidified hydrogen gas (3% moisture) at 800 ° C as fuel and ambient air as stationary oxidant. For reference, the graph of FIG. 6 shows the case where Co-Fe (15 wt%) catalyst is added.

Table 3 is a table showing the maximum power density (W / cm ² ) according to the cobalt content derived from FIG.

Cobalt content 0.2 0.3 0.4 Maximum power density 0.897 1.520 1.360

Referring to Table 3, the maximum power density of a solid oxide fuel cell including an anode of PBMCO according to an embodiment of the present invention was 0.897 W / cm ² to 1.520 W / cm ² at 800 ° C.

On the other hand, as a comparative example, when the anode is composed of SrTi _0.3 Fe _0.7 O ₃ -δ -GDC, the maximum power density was found to be 0.339 W / cm ² at 800 ° C. and the anode was composed of Sr ₂ MgMoO ₆ -δ The maximum power density was 0.838 W / cm ² at 800 ° C., and the maximum power density at 800 ° C. was 0.650 W / cm ² when the anode was composed of Sr ₂ MnMoO _6-δ . _0.8 Sr _1.2 (Co, Fe) _0.8 Nb _0.2 O _{4 + δ} , the maximum power density was found to be 0.900 W / cm ² at 800 ° C.

Therefore, the maximum power density of the solid oxide fuel cell including the anode of the PBMCO according to the embodiment of the present invention is the highest as compared with the comparative examples. As the cobalt content increases, the maximum power density increases and x can have the largest maximum power density in the range of 0.3 to 0.4.

7 is a graph showing a result of measuring the stability of a solid oxide fuel cell with respect to a PBMCO anode manufactured according to an embodiment of the present invention.

7 shows the result of measuring a change in current when a constant voltage of 600 mV is applied at 700 ° C for a predetermined time. Section " a "is a value measured under a hydrogen gas atmosphere, section" b "is a value measured under the condition of water bubbler under hydrogen gas and 20 ppm hydrogen sulfide (H ₂ S) atmosphere, "c" is a value measured under the condition of not generating water bubbles under a hydrogen gas and 20 ppm hydrogen sulfide (H ₂ S) atmosphere.

Referring to FIG. 7, it can be seen that the current density is stabilized in the sections "a", "b", and "c", and the current density is stable even under the hydrogen sulfide atmosphere like "c" .

Therefore, the PBMCO anode manufactured according to the present invention exhibits a stable current density in a hydrogen sulfide atmosphere, and thus has high stability against sulfur and high oxidation-reduction stability. Therefore, the PBMCO anode prepared according to the embodiment of the present invention, compared to the conventional Ni-YSZ having low stability against sulfur and low oxidation-reduction stability, can provide excellent effects.

According to the prior art, when nickel is used as an anode material and a hydrocarbon hydrocarbon is used as a fuel, resistance to carbon (C) and sulfur (S) contained in the fuel is low. Direct oxidation of hydrocarbons and carbon monoxide without the supply of steam to the dry fuel gas and without the application of a sufficiently high current density results in the formation of anodic materials by carbon deposition because nickel has the catalytic properties of forming carbon- There is a problem in that it is destroyed rapidly. Nickel is an excellent electrochemical catalyst for the electrochemical oxidation of hydrogen. However, when natural gas or hydrocarbon is directly used as a fuel, its activity is lowered by carbon deposition. When carbon is deposited on nickel particles, activation polarization ) Becomes very high, and the anode performance is deteriorated. However, PBMCO according to the technical idea of the present invention can solve problems such as carbon deposition of nickel.

While the present invention has been particularly shown and described with reference to certain exemplary embodiments thereof, it should be understood that the same is by way of illustration and example only and is not to be taken by way of limitation. It will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the appended claims. .

Accordingly, all equivalents of the claims and their equivalents, as well as the embodiments described hereinabove and the appended claims, are also within the scope of the inventive concept.

100: solid oxide fuel cell, 110: anode,
120: cathode, 130: electrolyte, 140: buffer layer

Claims (12)

Dissolving the metal precursors in a solvent;
After the dissolving step, obtaining ultrafine solid from the metal precursors through a spontaneous combustion process;
Sintering the ultrafine solid; And
And reducing the sintered ultrafine solid material in a hydrogen atmosphere to form a double layer perovskite structure on the sintered ultrafine solid material,
Wherein the metal precursors are mixtures of stoichiometric proportions capable of forming compounds of Formula 3: < EMI ID =
(3)
PrBaMn _2-x Co _x O _{5 +?}
In the formula (3), O is oxygen, x is a number of more than 0 and less than 1, and? Is a positive number of 0 or 1 or less. delete delete delete delete delete delete delete The method according to claim 1,
Wherein the PrBaMn _2-x Co _x O _{5 + delta} compound of Formula 3 comprises a compound having x in the range of 0.2 to 0.4. The method according to claim 1,
The PrBaMn _2-x Co _x O _{5 + delta} compound of the above formula (3) is preferably a PrBaMn _1.8 Co _0.2 O _{5 + delta} compound, a PrBaMn _1.7 Co _0.3 O _{5 + delta} compound or a PrBaMn _1.6 Co _0.4 O _{5 +} Method for manufacturing an anode material for a solid oxide fuel cell. delete delete

Images