KR101787811B1 - Method of manufacturing electrode, electrode manufactured by the method and fuel cell comprising the same - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing an electrode, an electrode thus manufactured, and a fuel cell including the same.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a method of manufacturing an electrode, an electrode manufactured thereby, and a fuel cell including the same. BACKGROUND ART < RTI ID = 0.0 >

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing an electrode, an electrode thus manufactured, and a fuel cell including the same.

The fuel cell can be classified into a polymer electrolyte membrane fuel cell (PEMFC), a direct methanol fuel cell (DMFC), an alkaline fuel cell (Alkaline Fuel Cell) (AFC), a phosphoric acid fuel cell (PAFC), a molten carbonate fuel cell (MCFC), and a solid oxide fuel cell (SOFC). In addition, depending on the electrolyte used, the operating temperature of the fuel cell and the material of the constituent part of the fuel cell vary.

Among them, the solid oxide fuel cell is a type of fuel cell, which is an energy conversion device that converts chemical energy having hydrogen and oxygen into direct electrical energy by electrochemical reaction. As a fuel cell, a high conversion efficiency and a large number of environmentally friendly Due to its advantages, it is attracting attention as a next generation energy conversion device.

At this time, the anode of the solid oxide fuel cell is preferably a porous membrane having a high electrical conductivity and an ionic conductivity, and having a thermal expansion coefficient similar to that of the electrolyte material, so that oxygen is easily transported. Accordingly, research is underway to develop particles suitable as a cathode material for a solid oxide fuel cell.

Korean Patent Publication No. 10-2005-0021027

The present specification aims to provide a method of manufacturing an electrode, an electrode thus manufactured, and a fuel cell including the same.

The present disclosure provides a method of making composite metal oxide particles, comprising the step of forming composite metal oxide particles using a flux of fluid.

The present invention also provides a method of manufacturing an electrode comprising forming an electrode using the composite metal oxide particles.

The present invention also provides an electrode manufactured by the method for manufacturing the electrode.

The present disclosure also provides an electrode comprising composite metal oxide particles made using a flux of fluid.

The present invention also provides a fuel cell including the electrode.

The present invention also provides a battery module including the fuel cell as a unit cell.

When preparing composite metal oxide particles according to the present specification, it is advantageous to synthesize particles having a large size at a low temperature.

According to the present invention, the dispersibility of the metal oxide particles in the electrode composition is improved.

There is an advantage that the porosity of the electrode can be easily controlled by using the electrode composition including the metal oxide particles synthesized according to the present specification.

1 is a scanning electron microscope (SEM) measurement photograph of the composite metal oxide particles prepared in Example 1. Fig.
2 is a scanning electron microscope (SEM) image of the composite metal oxide particles prepared in Comparative Example 1. FIG.

Hereinafter, the present application will be described in detail.

The present disclosure provides a method of making composite metal oxide particles, comprising the step of forming composite metal oxide particles using a flux of fluid.

Wherein the forming of the composite metal oxide particles comprises: preparing a mixture containing precursor particles of a flux and a composite metal oxide at room temperature; Heating the mixture to a temperature above the melting point of the flux; And forming the composite metal oxide particles using a fluid phase flux.

In preparing the mixture, the flux, which is solid at room temperature, may be mixed with the precursor particles of the composite metal oxide in a particulate state.

The step of forming the composite metal oxide particles may further include a step of preparing the mixture and then placing the prepared mixture in a closed space. This can be accomplished by introducing the prepared mixture into an enclosed space such that impurities do not participate in the reaction or the vaporized reactants in the mixture do not escape to the outside.

In the heating step, the temperature at which the temperature is finally raised may be a temperature equal to or higher than the melting point of the flux. At this time, when the temperature is raised to the temperature above the melting point of the flux, the solid phase flux becomes a fluid phase.

The temperature at which the temperature is finally raised in the heating step is not particularly limited as long as it is a temperature higher than the melting point of the flux and lower than the sintering temperature of the electrode to be described later.

Flux means a substance that acts to promote the melting of a substance at a temperature lower than the melting point of the substance.

In the present specification, the fluid phase flux means a flux in a fluid state, and may include a liquid phase flux and a gaseous phase flux.

The melting point of the flux is not particularly limited as long as it is lower than the sintering temperature of the electrode to be described later. For example, the melting point of the flux may be 800 ° C or more and 1,200 ° C or less.

In one embodiment of the present invention, the heating step may be a step of raising the melting point of the flux to a temperature below the breaking point. At this time, when the temperature is raised to a temperature lower than the melting point of the flux, the solid phase flux may become a liquid phase.

The temperature at which the temperature is finally raised may be a temperature lower than a melting point of the melting point, and is not particularly limited as far as the flux is in a liquid phase. For example, Lt; RTI ID = 0.0 > 1200 C. < / RTI >

In another embodiment of the present disclosure, the heating step may be a step of raising the temperature to a temperature above the breaking point of the flux. At this time, when the temperature is raised to a temperature higher than the breaking point of the flux, the solid phase flux may be in a gaseous phase.

The breaking point of the flux is not particularly limited as long as it is lower than the sintering temperature of the electrode to be described later. For example, the breaking point of the flux may be 800 ° C or more and 1,200 ° C or less.

Wherein the solid phase flux is a fluid phase and the fluid phase flux moves the precursor particles while repeating adsorption and desorption on the surface of the precursor particles of the composite metal oxide on the mixture, Metal oxide particles can be formed.

Specifically, when a fluid phase flux is adsorbed on the surface of the precursor particles of the composite metal oxide, the precursor particles can rotate, vibrate, or move, and through this movement, precursor particles of any one of the composite metal oxides can form another complex metal oxide Lt; RTI ID = 0.0 > metal oxide < / RTI >

In the present specification, when the flux is a gaseous flux, the gaseous flux causes the precursor particles to rotate, vibrate or move while repeatedly adsorbing and vaporizing on the surface of the precursor of the composite metal oxide particle to form composite metal oxide particles I can help.

The flux may comprise at least one of a metal chloride or a metal fluoride.

In one embodiment of the present disclosure, the temperature of the mixture comprising the precursor of the flux and the composite metal oxide particles is raised to a temperature above the melting point of the flux, so that in the flux comprising at least one of metal chloride or metal fluoride, The bonds with atoms are broken. At this time, at least one of chlorine and fluorine is generated, and at least one of generated chlorine and fluorine can help formation of the composite metal oxide while repeating adsorption and desorption on the surface of the precursor of the composite metal oxide particle.

The kind of the flux is not limited as long as the melting point or the breaking point is lower than the sintering temperature of the electrode. For example, the flux may be aluminum fluoride (AlF ₃ ), barium fluoride (BaF ₂ ) , barium chloride (BaCl _2, barium chloride), Lanthanum (ⅲ) chloride (LaCl _3, Lanthanum (ⅲ) chloride), cobalt (ⅱ) fluoride (CoF _2, cobalt (ⅱ) fluoride), and cerium (ⅲ) flow (CeF ₃ , cerium (III) fluoride).

The larger the amount of the flux in the mixture, the larger the size of the composite metal oxide particles, but the flux forms impurities in the composite metal oxide particles and the flux is an impurity. If the influence of the flux on the properties of the composite metal oxide particles is large due to a large amount of the flux, it may be necessary to remove the flux.

In one embodiment of the present disclosure, when preparing a mixture comprising precursors of the flux and composite metal oxide particles, the content of the flux, based on the total weight of the precursors of the composite metal oxide particles in the mixture, is at least 0.1 wt% 2% by weight or less. When the flux is used in an amount of less than 0.1% by weight, the particles are not effective for growth and shape control. When the flux is used in an amount exceeding 2% by weight, the composite metal oxide particles become unnecessarily large or the necking of the particles becomes severe, It is not suitable for use as a material.

In this specification, the precursor of the composite metal oxide particles refers to a material before the composite metal oxide particle to be produced is formed. Specifically, the precursor of the composite metal oxide particles is at least two kinds of metal oxides including one or more metal particles among the composite metal oxides to be produced.

In one embodiment of the present invention, the precursor of the composite metal oxide particle is not particularly limited as long as it is a metal oxide containing one or more metal particles among the composite metal oxides to be produced.

For example, a complex metal oxide to produce _{La 0 .6 Sr 0 .4 Co 0} .2 Fe 0 .8 O _{3 -δ} if the precursor of the composite metal oxide particles is more than lanthanide (La); Strontium (Sr); Cobalt (Co); And an iron content of at least one of iron oxide, iron nitrate, and iron sulfate. Here, in a perovskite structure having a basic composition of ABO ₃ (A and B are trivalent metals), when a part of a trivalent metal (such as La) is substituted with a bivalent metal (such as Sr) Oxygen vacancies occur to match the oxygen content of the particles, resulting in oxygen in the particles less than 3 being present as "O _{3 -δ} ".

The metal is recombined between two or more metal oxides which are precursors of the composite metal oxide particles through the fluid phase flux to form a composite metal oxide.

The average diameter of the composite metal oxide particles may be 100 nm or more and 3 占 퐉 or less. In this case, since there is no necking that interferes with the dispersion between the particles, there is an advantage that the particles are well dispersed. Specifically, the average diameter of the composite metal oxide particles may be 500 nm or more and 3 占 퐉 or less. If necessary, the average diameter of the composite metal oxide particles may be 1 탆 or more and 3 탆 or less.

The temperature for forming the composite metal oxide particles may be 800 ° C or higher and 1,200 ° C or lower.

The composite metal oxide particles having an average diameter of 100 nm or more and 3 占 퐉 or less can be formed at a temperature of 800 占 폚 to 1,200 占 폚.

When an anode material is synthesized at a very high temperature (higher than 1,200 ° C.) in order to increase the crystallinity and particle size of the cathode material, necking phenomenon between the particles is so severe that there arises a problem in the dispersion of the anode material particles in the production of the cathode composition .

On the other hand, the composite metal oxide particles produced according to the present invention are advantageous in that there is little or no necking between particles because they are synthesized at a relatively low temperature, and that the diameter is large and the shape is controlled.

In addition, the dispersibility of the composite metal oxide particles in the preparation of the electrode composition is good, and the electrode made from such an electrode composition has an advantage that the pores are uniformly distributed and the appropriate porosity is obtained.

In this specification, the diameter means the length of the longest straight line passing through the center of gravity of the particle.

In the present specification, the shape of the particles is a round shape without edges, and may be spherical or elliptical in shape, but is not limited thereto.

The composite metal oxide particles may be perovskite type oxide particles.

In this specification, the perovskite-type oxide particles mean metal oxide particles of a cubic crystal structure which exhibits superconductivity as well as the properties of non-conductors, semiconductors and conductors.

Perovskite type oxide particles can be represented by ABO ₃ where A is the vertex of the cubic unit and B is the center of the cubic unit, It has coordination number. At this time, the cation of any one or two or more elements selected from the rare earth element, the alkaline earth metal element and the transition element may be located in A and / or B.

For example, A has one or more cations with large and low valences, B has a small, generally high valence cation, and the metal atoms at positions A and B have six oxygen atoms in the octahedral configuration Ions.

In the perovskite-type oxide particles, A may contain cations of one or more elements selected from among rare earth elements, alkaline earth metal elements, and transition elements, and B may include cations of the transition metal. For example, the transition metal of B may be a cation of a metal selected from Ti, Cr, Mn, Ni, Fe, Co, Cu and Zr.

The composite metal oxide particles are not particularly limited as long as they are perovskite type oxide particles, and examples thereof include lanthanum strontium manganese oxide (LSM), lanthanum strontium cobalt ferrite (LSCF), lanthanum strontium A lanthanum strontium nickel ferrite (LSNF), a lanthanum calcium nickel ferrite (LCNF), a lanthanum strontium copper oxide (LSC) ) Gadolinium strontium cobalt oxide (GSC), lanthanum strontium ferrite (LSF), samarium strontium cobalt oxide (SSC), and barium strontium cobalt ferrite (BSCF) ) ≪ / RTI > Can.

In the present specification, the method may further include the step of purifying the composite metal oxide particles formed after forming the composite metal oxide particles. Specifically, after the composite metal oxide particles are formed, the composite metal oxide particles can be removed from the fluid such as flux, impurities, and the like.

When the flux is removed during the purification of the composite metal oxide particles, elements such as chlorine or fluorine atoms are removed in addition to the metal in the flux, and the metal contained in the flux is present in the composite metal oxide particle. Since the metal contained in the flux remains in the composite metal oxide particles after the flux is removed in this way, it is preferable to use the flux at a minimum in forming the composite metal oxide particles.

The present invention also provides a method of manufacturing an electrode comprising forming an electrode using the composite metal oxide particles.

In particular, the present disclosure relates to a method of forming composite metal oxide particles using a fluid flux; And forming an electrode using the formed composite metal oxide particles.

The step of forming the electrode may include a step of applying an electrode composition including the formed composite metal oxide particles on a substrate, followed by sintering (heat treatment).

The electrode composition may further include at least one of a solvent, a dispersant, a binder and a plasticizer. The electrode composition can prevent agglomeration of metal oxide particles and can agitate using a ball mill and ultrasonic waves.

The solvent is not limited as far as it is easy to disperse the composite metal oxide particles and easily remove after coating the electrode composition, and conventional materials known in the art can be used. For example, the solvent may comprise at least one selected from water, isopropanol, toluene, ethanol, n-propanol, n-butyl acetate, ethylene glycol, butyl carbitol (BC) and butyl carbitol acetate .

The content of the composite metal oxide particles may be 20 wt% or more and 80 wt% or less based on the total weight of the electrode composition.

The electrode manufactured in the step of forming the electrode may be a porous electrode. Specifically, the electrode formed by applying the electrode composition containing the composite metal oxide particles may be a porous electrode by forming an air gap between the composite metal oxide particles.

The porosity of the porous electrode may be 10% or more and 60% or less. When the pore is too small, the oxygen is difficult to move to the interface between the electrolyte and the anode, and thus the concentration of the concentration is greatly increased. As a result, the electrode performance deteriorates. When the pore is too large, Fall off.

In the step of forming the electrode, the temperature at which the electrode composition is coated on the substrate and then sintered may be 800 ° C or higher and 1,200 ° C or lower.

In the step of forming the composite metal oxide particles of the present invention, the melting point or breaking point of the flux is preferably lower than the sintering temperature of the electrode.

The present invention provides an electrode manufactured by the method for manufacturing the electrode.

The present disclosure provides an electrode comprising composite metal oxide particles made using a flux of fluid.

The thickness of the electrode may be 5 占 퐉 or more and 100 占 퐉 or less.

The electrode may be a porous electrode.

The porosity of the porous electrode may be 10% or more and 60% or less. When the pore is too small, the oxygen is difficult to move to the interface between the electrolyte and the anode, and thus the concentration of the concentration is greatly increased. As a result, the electrode performance deteriorates. When the pore is too large, Fall off.

The electrode may be an electrode for a fuel cell, specifically, a cathode for a fuel cell.

The present invention provides a fuel cell including the electrode.

The fuel cell may be a fuel cell such as a phosphoric acid fuel cell (PAFC), an alkaline fuel cell (AFC), a polymer electrolyte fuel cell (PEMFC), a direct methanol fuel cell (DMFC), a molten carbonate fuel cell (MCFC) SOFC). Among them, the fuel cell according to the present invention is preferably a solid oxide fuel cell (SOFC).

The electrode may be a cathode for a fuel cell, specifically, a cathode for a solid oxide fuel cell.

The anode for a solid oxide fuel cell has a high electrical conductivity and an ion conductivity, and is preferably a porous membrane so that the thermal expansion coefficient is similar to that of the electrolyte material, and oxygen is easily migrated.

The fuel cell includes a cathode; And an electrolyte membrane provided between the anode and the cathode.

The present specification provides a battery module including the fuel cell as a unit cell.

Wherein the battery module comprises: a stack including a unit cell including the fuel cell and a separator provided between the unit cells; A fuel supply unit for supplying fuel to the stack; And an oxidant supply for supplying the oxidant to the stack.

Hereinafter, the present invention will be described in more detail by way of examples. However, the following embodiments are intended to illustrate the present disclosure and are not intended to limit the present disclosure.

[Example]

[Example 1]

0.5 mol of lanthanum oxide (La ₂ O ₃ ), 0.4 mol of strontium carbonate (SrCO ₃ ), 0.0667 mol of cobalt oxide (Co ₃ O ₄ ) and 0.4 mol of iron oxide (Fe ₂ O ₃ ) were weighed as a precursor of composite metal oxide particles (AlF ₃ ) was added as a flux in an amount of 1% by weight based on the total weight of the precursors of the composite metal oxide particles. The precursor and flux of the composite metal oxide particles were uniformly mixed with a ball mill, and the mixture was placed in an alumina crucible. The mixture was placed in an atmosphere atmosphere furnace, heated to 5 ° C / min, and heat-treated at 1,200 ° C for 2 hours Lt; RTI ID = 0.0 > 5 C < / RTI > per minute to produce lanthanum strontium cobalt ferrite (LSCF) particles having an average diameter of 1.5 m.

[Comparative Example 1]

0.5 mol of lanthanum oxide (La ₂ O ₃ ), 0.4 mol of strontium carbonate (SrCO ₃ ), 0.0667 mol of cobalt oxide (Co ₃ O ₄ ) and 0.4 mol of iron oxide (Fe ₂ O ₃ ) were weighed and uniformly dispersed with a ball mill Mixed. This was placed in an alumina crucible, placed in an atmospheric furnace, heated to 5 ° C / min, annealed at 1,200 ° C for 2 hours and then cooled down to 5 ° C / min to produce lanthanum strontium cobalt ferrite particles having an average diameter of 500 nm.

[Experimental Example]

Electrical conductivity

The most important electrical conductivity was measured with the powder synthesized in Example 1 or Comparative Example 1 as the anode material characteristic. The electrical conductivity specimens were measured using the 4-point probe method with a fixed length between the measuring terminals of 10 mm. In order to minimize the potential difference error between the two terminals, platinum paste (Pt wire) was used as a terminal and platinum wire (lead wire) was used as a terminal.

The test specimens were made in the shape of a square mold and pressed unilaterally. The compressive force was 2 ton. The dimension of the specimen was constantly set to 40 mm x 10 mm x 3 mm and sintered at 1000 ° C for 2 hours. Next, a current and potential measurement terminal was made with Pt electrode pasting, and then platinum was sintered at 1000 ° C again. The measurement conditions were raised to 5 ° C / min up to the measurement temperature and the electrical conductivity was measured in real time using a 4-point probe conductivity test.

The results are shown in Table 1 below. It can be seen that the electric conductivity of particles of Example 1 is higher than that of Comparative Example 1 at 500 ° C or 600 ° C.

Claims (21)

Preparing a mixture comprising precursor particles of a flux and a composite metal oxide at room temperature; Raising the mixture to a temperature above the melting or breaking point of the flux; Forming composite metal oxide particles using a fluid flux; And removing the flux from the composite metal oxide particles,
The flux is aluminum fluoride (AlF _3, Aluminium fluoride), barium fluoride (BaF _2, Barium fluoride), barium chloride (BaCl _2, Barium chloride), Lanthanum (Ⅲ) chloride (LaCl _3, Lanthanum (Ⅲ) chloride ), At least one of cobalt (II) fluoride (CoF ₂ , Cobalt (II) fluoride) and cerium (III) fluoride (CeF ₃ )
The flux phase is a liquid or gas,
Wherein the melting point of the flux is 800 ° C or higher and 1,200 ° C or lower when the flux is a liquid and the breaking point of the flux is 800 ° C or higher and 1,200 ° C or lower when the flux is gaseous. Way. The method for producing composite metal oxide particles according to claim 1, wherein the temperature for forming the composite metal oxide particles is 800 ° C or more and 1,200 ° C or less. delete delete The method for producing composite metal oxide particles according to claim 1, wherein the composite metal oxide particles are perovskite type particles. The method of producing a composite metal oxide particle according to claim 1, wherein the composite metal oxide particles have an average diameter of 100 nm or more and 3 m or less. delete delete delete delete A method of manufacturing an electrode, comprising forming an electrode using composite metal oxide particles produced according to any one of claims 1, 2, 5 and 6. 12. The method of claim 11, wherein the electrode is a porous electrode. [12] The method of claim 12, wherein the porosity of the porous electrode is 10% or more and 60% or less. 12. The method of claim 11, wherein forming the electrode comprises applying an electrode composition comprising the composite metal oxide particles formed on a substrate and sintering. delete delete delete delete delete delete delete

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