KR101615694B1 - 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. The anode material in accordance with one embodiment of the present invention include compounds of the _{RE 1-x E 'x T} 2 O 5 + δ. 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.

Japanese Patent No. 422203

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 >

RE _1-x E ' _x T ₂ O _{5 +?}

Wherein R comprises one or more elements selected from rare earth elements or lanthanides, E and E 'comprise different elements selected from the group of the alkaline earth metals, T is 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, and the value of the compound of formula (1) is an electrical neutrality.

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 and E 'may include barium Ba, calcium Ca, or strontium Sr.

In one embodiment of the present invention, E 'may substitute E for occupying the position of E in the compound of formula (1).

In one embodiment of the present invention, the T may include manganese (Mn).

In one embodiment of the present invention, the RE _1-x E ' _x T ₂ O _{5 + δ} compound of Formula 1 may have a bilayer perovskite structure.

In one embodiment of the present invention, the RE _1-x E ' _x T ₂ O _{5 + δ} compound of Formula 1 may include a compound of Formula 2 below.

(2)

_{PrBa 1-x E 'x Mn} 2 O 5 + δ

In Formula 2, E 'includes one or more elements selected from the group of the alkaline earth metal, O is oxygen, x is a number of more than 0 and less than 1, and 隆 is 0 or a positive number of 1 or less , Which is a value that makes the compound of formula (2) electrically neutral.

In one embodiment of the present invention, PrBa of Formula _{2 1-x E 'x Mn} 2 O 5 + δ compound is _{PrBa 1-x Sr x Mn 2} O 5 + δ compound or PrBa _1-x Ca _x Mn of ₂ O _{5 + delta} .

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)

PrBa _0.8 Sr _0.2 Mn ₂ O _{5 +?}

In the formula (3), O is oxygen, and the delta is a positive number of 0 or 1 or less, and the compound of the formula (3) is a value that is electrically neutral.

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

≪ Formula 4 >

PrBa _0.8 Ca _0.2 Mn ₂ O _{5 +?}

In Formula 4, O is oxygen, and? Is a positive number of 0 or 1 or less, and the compound of Formula 4 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 (5).

≪ Formula 5 >

PrBa _0.8 (Sr, Ca) _0.2 Mn ₂ O _{5 +?}

In the above formula (5), O is oxygen, and? Is a positive number of 0 or 1 or less, and the compound of the formula (5) is a value that is electrically neutral.

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, PBSMO and PBCMO 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 the electrical conductivity of an anode of PBSMO prepared according to the first embodiment of the present invention at 5% H ₂ .
FIG. 4 is a graph showing a Nyquist plot showing a frequency spectrum of an impedance according to temperature when hydrogen is used as a fuel for an anode of PBSMO manufactured according to the first embodiment of the present invention. FIG.
5 is a graph showing IV polarization curves and maximum power densities of a fuel cell according to temperature when hydrogen is used as a fuel for a solid oxide fuel cell including an anode of PBSMO manufactured according to the first embodiment of the present invention to be.
6 is a graph showing the electrical conductivity of the anode of PBCMO prepared according to the second embodiment of the present invention at 5% H ₂ .
FIG. 7 is a graph showing a Nyquist plot showing a frequency spectrum of an impedance according to temperature when hydrogen is used as a fuel for an anode of a PBCMO manufactured according to a second embodiment of the present invention.
8 is a graph showing the IV polarization curves and the maximum power density of a fuel cell according to temperature when hydrogen is used as a fuel for a solid oxide fuel cell including an anode of PBCMO manufactured according to the second embodiment of the present invention to be.
9 is a graph showing a Nyquist plot showing the frequency spectrum of impedance according to temperature when propane is used as fuel for the anode of PBCMO manufactured according to the second embodiment of the present invention.
10 is a graph showing IV polarization curves and maximum power densities of a fuel cell according to temperature when propane is used as a fuel for a solid oxide fuel cell including an anode of PBCMO manufactured according to the second embodiment of the present invention to be.

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 >

RE _1-x E ' _x T ₂ O _{5 +?}

In Formula 1, R may include one or more elements selected from a rare earth group or a lanthanide group, and E and E 'may include different elements selected from an alkaline earth metal group, The transition metal may comprise one or more elements selected from transition metals, O is oxygen, x is a number greater than 0 and less than 1, and? Is a positive number equal to or less than 0 or 1, .

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 and E 'may include one or more elements selected from the group of the alkaline metal, and may include, for example, barium Ba, calcium Ca, or strontium Sr. The E 'may be an element that substitutes the E to occupy the position of E in the compound of Formula 1. The substitution may increase the thermal stability and chemical stability of the anode.

The T may include one or more elements selected from transition metals, and may include, for example, manganese (Mn).

O is oxygen. Is a positive number of 1 or less, and the value of the compound of the formula (QBaMnO5 _{+ delta} ) 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)

_{PrBa 1-x E 'x Mn} 2 O 5 + δ

In Formula 2, E 'may include one or more elements selected from an alkaline earth metal group, and may include, for example, calcium (Ca) or strontium (Sr). 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 compounds of the formula (II), may comprise a compound of _{PrBa 1-x Sr x Mn 2} O 5 + δ compound or _{PrBa 1-x Ca x Mn 2} O 5 + δ of.

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

(3)

PrBa _0.8 Sr _0.2 Mn ₂ O _{5 +?}

In the formula (3), O is oxygen, and the delta is a positive number of 0 or 1 or less, and the compound of the formula (3) is a value that is electrically neutral.

The anode according to an embodiment of the present invention may include a compound represented by the following formula (4).

&Lt; Formula 4 >

PrBa _0.8 Ca _0.2 Mn ₂ O _{5 +?}

In Formula 4, O is oxygen, and? Is a positive number of 0 or 1 or less, and the compound of Formula 4 is a value that is electrically neutral.

The anode according to one embodiment of the present invention may include a compound of the following formula (5).

&Lt; Formula 5 >

PrBa _0.8 (Sr, Ca) _0.2 Mn ₂ O _{5 +?}

In the above formula (5), O is oxygen, and? Is a positive number of 0 or 1 or less, and the compound of the formula (5) is a value that is electrically neutral. The above (Sr, Ca) includes strontium and calcium, and calcium substitutes for some of the positions occupied by strontium in the structure of formula (3), or a part of the positions occupied by calcium in the structure of formula Strontium is replaced by something else.

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 mixing each of the metal precursors metered in accordance with the composition of the RE _1-x E ' _x T ₂ O _{5 + δ} compound of Formula 1 (for example, wet using a solvent) , Obtaining a solid from the (wet) mixture, firing the solid 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, E ', T, etc. constituting the anode material of the above formula. For example, the compound forming the anode is PrBa _0.8 Ca _0.2 Mn ₂ O _{5 +?} Compound of the formula (3), and the metal precursor is at least one compound selected from the group consisting of nitrides, oxides, Halides and the like. For example, the compound forming the anode is PrBa _0.8 Sr _0.2 Mn ₂ O _{5 +}隆 compound of Formula 4, and the metal precursor is at least one compound selected from the group consisting of nitrides, oxides, Halides and the like.

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.

[First Embodiment]

Hereinafter, the first embodiment will be described in order to explain the present invention in detail by way of example. The first embodiment is characterized in that strontium is contained in the anode material. The first embodiment is not intended to limit the scope of the invention.

Of the compounds of RE _1-x E ' _x T ₂ O _{5 +?} Of the above formula (1), PrBa _0.8 Sr _0.2 Mn ₂ O _{5 + delta} was selected as the anode material. Hereinafter, the above-mentioned PrBa _0.8 Sr _0.2 Mn ₂ O _{5 + delta} is referred to as "PBSMO &quot;.

To form the PBSMO, the 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; And reduced in an atmosphere of 100% H ₂ (corresponding to 3% H ₂ O) to form a bilayer perovskite structure, followed by formation of a PBSMO anode material. The anode material was pulverized and then 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 at about 1475 ° C for 5 hours in the air and polished to obtain a dense electrolyte with a thickness of about 300 μm. Next, a cathode slurry containing PrBa _0.5 Sr _0.5 Co _1.5 Fe _0.5 -GDC (PBSCF-GDC), a buffer layer slurry containing La _0.4 Ce _0.6 O ₂ -δ (LDC), and a slurry containing PrBa _0.8 Sr _0.2 Mn ₂ O _{5 + &lt;} RTI ID = 0.0 &gt; (PBSMO) _{&lt; /} RTI &gt; were each screen printed onto the electrolyte and sintered in air at about 950 DEG C for about 4 hours to produce a fuel cell.

The thicknesses of the anode, cathode, and electrolyte formed as described above were about 50 μm, about 50 μm, and about 300 μm, respectively. Silver wires were attached to the cathode and anode using silver paste for current collection. In addition, 15 wt% of Co-Fe catalyst was added to the PBSMO anode to show the catalytic effect.

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

FIG. 3 is a graph showing the electrical conductivity of an anode of PBSMO 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 voltage were measured using BioLogic's constant potential device (Potentiaostat) at intervals of about 50 占 폚 in a measuring interval of about 100 占 폚 to about 900 占 폚.

Referring to FIG. 3, the electrical conductivity of the anode of PBSMO according to the first embodiment of the present invention tends to increase with increasing temperature (i.e., moving to the left). The measured conductivity of the anode of PBSMO was 2.14 s / cm at 750 캜. 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 electrical conductivity of the anode of PBSMO according to the first embodiment of the present invention is higher than that of the comparative example.

FIG. 4 is a graph showing a Nyquist plot showing a frequency spectrum of an impedance according to temperature when hydrogen is used as a fuel for an anode of PBSMO manufactured according to the first embodiment of the present invention. FIG.

Referring to FIG. 4, the ohmic resistance, non-ohmic resistance, and total resistivity of the unit cell can be calculated according to the temperature, and the power density can be derived from the resistance values. For example, the x-intercept value of the high frequency corresponds to the ohmic resistivity (R _ohm ), the x-intercept value of the low frequency corresponds to the ohmic resistivity and the total resistivity (R _p ) value . The resistivity value (R) for the unit area can be derived by dividing the total resistivity by the total area (0.36 cm ^{2 in} FIG. 4). Then, the power density of one unit cell can be obtained from the formula "P = VI = I ² R &quot;, and the power density per unit area can be obtained by dividing the power density by the total area. In this way, the power density shown in the graph of FIG. 5 below can be obtained.

5 is a graph showing IV polarization curves and maximum power densities of a fuel cell according to temperature when hydrogen is used as a fuel for a solid oxide fuel cell including an anode of PBSMO manufactured according to the first embodiment of the present invention to be.

In FIG. 5, 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. 5 were measured at 700 ° C to 800 ° C using a constant potential device from BioLogic. Specifically, the I-V polarization curves used humidified hydrogen gas (3% moisture) as fuel and ambient air as a oxidant at 700 ° C to 800 ° C. For reference, the graph of FIG. 5 shows a case where Co-Fe (15 wt%) catalyst is added.

Table 1 shows the maximum power density (W / cm ² ) according to the temperature derived from FIG.

Temperature 700 ℃ 750 ℃ 800 ° C Maximum power density 0.443 0.646 1.014

Referring to Table 1, the maximum power density of the solid oxide fuel cell including the anode of the PBSMO according to the first embodiment of the present invention was 1.014 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 PBSMO according to the first embodiment of the present invention was the highest in comparison with the comparative examples.

[Second Embodiment]

Hereinafter, the second embodiment will be described in order to explain the present invention in detail by way of example. The second embodiment differs from the anode material in that calcium is contained in place of the strontium of the first embodiment described above. The second embodiment is not intended to limit the scope of the present invention.

Among the compounds of RE _1-x E ' _x T ₂ O _{5 +?} Of the above formula (1), PrBa _0.8 Ca _0.2 Mn ₂ O _{5 + delta} was selected as the anode material. Hereinafter, the above-mentioned PrBa _0.8 Ca _0.2 Mn ₂ O _{5 + delta} will be referred to as "PBCMO &quot;.

To form the PBCMO, the 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; And reduced in an atmosphere of 100% H ₂ (corresponding to 3% H ₂ O) to form a bilayer perovskite structure to form a PBCMO anode material. The anode material was pulverized and then 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 PrBa _0.5 Sr _0.5 Co _1.5 Fe _0.5 -GDC (PBSCF-GDC), a buffer layer slurry containing La _0.4 Ce _0.6 O ₂ -δ (LDC), and a slurry containing PrBa _0.8 Ca _0.2 Mn ₂ O _{5 +} (PBCMO) were each screen-printed on the electrolyte, and then sintered in air at about 950 DEG C for about 4 hours to prepare a fuel cell.

The thicknesses of the anode, cathode, and electrolyte formed as described above were about 20 mu m, about 20 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 PBCMO anode to show the catalytic effect.

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

6 is a graph showing the electrical conductivity of the anode of PBCMO prepared according to the second 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 voltage were measured using BioLogic's constant potential device (Potentiaostat) at intervals of about 50 占 폚 in a measuring interval of about 100 占 폚 to about 900 占 폚.

Referring to Figure 6, in _{PrBa 1-x Ca x Mn 2} O 5 + δ, exhibited an electrical conductivity byeonhwadoem according to the content of x. When x is 0 (that is, PrBaMn ₂ O _{5 + delta} , density is 77%), the range of electric conductivity is 2.456 to 0.099 (s / cm) _{0.9 x} Ca _0.1 Mn ₂ O _{5 + delta} and a density of 88%) and an electric conductivity range of 3.878 to 0.122 (s / cm). When x is 2 (that is, PrBa _0.8 Ca _0.2 Mn ₂ O _{5 + δ,} density 80%), the range of electrical conductivity showed as a 5.477 to 0.164 (s / cm), (that _{is, PrBa 0.7 Ca 0.7 Mn 2 O} 5 + δ, density of 87% when the above x is 3) , And the range of electric conductivity was 4.309 to 0.147 (s / cm). Therefore, when x is 2, that is, PrBa _0.8 Ca _0.2 Mn ₂ O _{5 + δ} has the highest electrical conductivity as compared to other calcium contents.

The electrical conductivity of the anode of the PBCMO according to the second embodiment of the present invention showed a tendency to increase with increasing temperature (i.e., moving to the left). Also, the measured conductivity of the anode of PBCMO was 4.298 s / cm at 750 캜. 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 the PBCMO according to the second embodiment of the present invention is higher than that of the comparative example.

FIG. 7 is a graph showing a Nyquist plot showing a frequency spectrum of an impedance according to temperature when hydrogen is used as a fuel for an anode of a PBCMO manufactured according to a second embodiment of the present invention.

Referring to FIG. 7, as described with reference to FIG. 4, the power density shown in the graph of FIG. 8 below can be obtained.

8 is a graph showing the IV polarization curves and the maximum power density of a fuel cell according to temperature when hydrogen is used as a fuel for a solid oxide fuel cell including an anode of PBCMO manufactured according to the second embodiment of the present invention to be.

In FIG. 8, 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. 8 were measured at 700 ° C to 800 ° C using a constant potential device from BioLogic. Specifically, the I-V polarization curves used humidified hydrogen gas (3% moisture) as fuel and ambient air as a oxidant at 700 ° C to 800 ° C. For reference, the graph of FIG. 8 shows a case where Co-Fe (15 wt%) catalyst is added.

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

Temperature 700 ℃ 750 ℃ 800 ° C Maximum power density 0.897 1.258 1.907

Referring to Table 2, the maximum power density of the solid oxide fuel cell including the anode of the PBCMO according to the second embodiment of the present invention was found to be 1.907 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 0.900 W when the anode was composed of Pr _0.8 Sr _1.2 (Co, Fe) _0.8 Nb _0.2 O _{4 +} / cm &lt; ² &gt;. Therefore, the maximum power density of the solid oxide fuel cell including the anode of the PBCMO according to the second embodiment of the present invention is the highest in comparison with the comparative examples.

9 is a graph showing a Nyquist plot showing the frequency spectrum of impedance according to temperature when propane is used as fuel for the anode of PBCMO manufactured according to the second embodiment of the present invention.

Referring to FIG. 9, as described with reference to FIG. 4, the power density shown in the graph of FIG. 10 below can be obtained.

10 is a graph showing IV polarization curves and maximum power densities of a fuel cell according to temperature when propane is used as a fuel for a solid oxide fuel cell including an anode of PBCMO manufactured according to the second embodiment of the present invention to be.

In FIG. 10, 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. 10 were measured at 700 ° C to 800 ° C using a constant potential device from BioLogic. Specifically, the I-V polarization curve used humidified propane gas (3% moisture) as fuel and ambient air at rest as an oxidizing agent at 700 ° C to 800 ° C. For reference, the graph of Fig. 10 shows a 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 temperature derived from FIG.

Temperature 700 ℃ 750 ℃ 800 ° C Maximum power density 0.120 0.369 0.970

Referring to Table 3, the maximum power density of the solid oxide fuel cell including the anode of the PBCMO according to the second embodiment of the present invention was 1.907 W / cm ² at 800 ° C. On the other hand, as a comparative example, when the anode is composed of Pr _{0 .8} Sr _{1 .2} (Co, Fe) _0.8 Nb _{0 .2} O _{4 + δ} , the maximum power density at 900 ° C. is 0.970 W / cm ² . Therefore, the maximum power density of the solid oxide fuel cell including the anode of the PBCMO according to the second embodiment of the present invention was higher than that of the comparative example even when propane was used as the fuel.

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, PBSMO and PBCMO 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 (13)

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 (2): < EMI ID =
(2)
RBa _1-x E ' _x Mn ₂ O _{5 +?}
Wherein R comprises one or more elements selected from rare earth elements or lanthanides, E 'comprises one or more elements selected from the group of the alkaline earth 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, and the compound of the formula (2) is a value that is electrically neutral. The method according to claim 1,
The R may be at least one selected from the group consisting of Y, Sc, Sm, Gd, Nd, Pr, Si, Gd, Eu, (Tb), erbium (Er), or mixtures thereof. The method according to claim 1,
Wherein E 'comprises barium Ba, calcium Ca, or strontium Sr. A method of making an anode material for a solid oxide fuel cell, delete delete delete delete The method according to claim 1,
_{RBa 1-x E 'x Mn} 2 O 5 + δ compound of Formula 2 is a compound of PrBa _1-x Sr _x Mn ₂ O _{5 + δ} compound or PrBa _1-x Ca _x Mn ₂ O _{5 + δ} of Wherein the solid oxide fuel cell is a cathode. 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)
PrBa _0.8 Sr _0.2 Mn ₂ O _{5 +?}
In the formula (3), O is oxygen, and the delta is a positive number of 0 or 1 or less, and the compound of the formula (3) is a value that is electrically neutral. 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 (4): < EMI ID =
&Lt; Formula 4 &gt;
PrBa _0.8 Ca _0.2 Mn ₂ O _{5 +?}
In Formula 4, O is oxygen, and? Is a positive number of 0 or 1 or less, and the compound of Formula 4 is a value that is electrically neutral. 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 producing compounds of formula (5): < EMI ID =
&Lt; Formula 5 &gt;
PrBa _0.8 (Sr, Ca) _0.2 Mn ₂ O _{5 +?}
In the above formula (5), O is oxygen, and? Is a positive number of 0 or 1 or less, and the compound of the formula (5) is a value that is electrically neutral. delete delete

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