KR20200017685A - Cathode composition for solid oxide fuel cell, cathode, manufacturing method thereof and solid oxide fuel cell - Google Patents

Abstract

Provided are a cathode composition for a solid oxide fuel cell, a cathode for a solid oxide fuel cell comprising the same, a manufacturing method thereof, and a solid oxide fuel cell. The cathode composition comprises a compound represented by chemical formula 1, BaCo_0.4Fe_0.4Zr_(0.2-x1)Y_(x1)O_(3-δ), and a compound represented by chemical formula 2, La_(1-x2)Sr_(x2)CoO_(3-δ). According to the present invention, it is possible to increase durability and actual performance of the solid oxide fuel cell.

Description

Cathode composition for a solid oxide fuel cell, a cathode, a manufacturing method thereof, and a solid oxide fuel cell TECHNICAL FIELD

The present specification relates to a cathode composition for a solid oxide fuel cell, a cathode for a solid oxide fuel cell including the same, a method for manufacturing the same, and a solid oxide fuel cell.

Recently, as the depletion of existing energy resources such as oil and coal is predicted, interest in energy that can replace them is increasing. As one of the alternative energy sources, the fuel cell has received particular attention due to its advantages such as high efficiency, no pollutants such as NOx and SOx, and abundant fuel.

A fuel cell is a power generation system that converts chemical reaction energy of fuel and oxidant into electrical energy. Hydrogen, hydrocarbons such as methanol, butane, and the like are typically used as fuel, and oxygen is used as the oxidant.

Fuel cells include polymer electrolyte fuel cells (PEMFC), direct methanol fuel cells (DMFC), phosphoric acid fuel cells (PAFC), alkaline fuel cells (AFC), molten carbonate fuel cells (MCFC), and solid oxide fuels. Batteries (SOFC) and the like.

On the other hand, it is also necessary to study the metal air secondary battery for manufacturing the cathode of the metal secondary battery as the cathode by applying the principle of the cathode of the fuel cell.

Korean Patent Publication No. 2012-0110787

The present specification provides a cathode composition for a solid oxide fuel cell, a cathode, a cathode for a fuel cell including the same, and a method of manufacturing the same.

An exemplary embodiment of the present specification provides a cathode composition for a solid oxide fuel cell comprising a compound represented by Formula 1 and a compound represented by Formula 2.

[Formula 1]

BaCo _0.4 Fe _0.4 Zr _0.2-x1 Y _x1 O _3-δ

[Formula 2]

La _1-x2 Sr _x2 CoO _3-δ

In Chemical Formula 1 and Chemical Formula 2,

0 ≦ x1 ≦ 0.2, 0 ≦ x2 <1, and δ is 0 or more and 0.3 or less.

An exemplary embodiment of the present specification provides a cathode for a solid oxide fuel cell including the cathode composition for the solid oxide fuel cell.

An exemplary embodiment of the present specification comprises the steps of synthesizing the compound represented by the formula (1) and the compound represented by the formula (2) by using a solid phase synthesis method; And preparing a cathode composition for a solid oxide fuel cell by mixing the compound represented by the following Chemical Formula 1 and the compound represented by the following Chemical Formula 2 synthesized by the synthesizing step: Provide a method.

[Formula 1]

BaCo _0.4 Fe _0.4 Zr _0.2-x1 Y _x1 O _3-δ

[Formula 2]

La _1-x2 Sr _x2 CoO _3-δ

In Chemical Formula 1 and Chemical Formula 2,

0 ≦ x1 ≦ 2, 0 ≦ x2 <1, and δ is 0 or more and 0.3 or less.

In addition, an exemplary embodiment of the present specification is the cathode; Anode; And it provides a solid oxide fuel cell comprising an electrolyte layer provided between the cathode and the anode.

By manufacturing a solid oxide fuel cell including a cathode composition for a solid oxide fuel cell according to one embodiment of the present specification and operating at a low temperature (600 to 700 ° C.), it is possible to increase the actual performance and durability of the solid oxide fuel cell.

1 schematically shows the electricity generation principle of a solid oxide fuel cell.
2 is a measured image of a scanning electron microscope (SEM) of a solid oxide fuel cell according to one embodiment of the present specification.
3 shows an EDX analysis image of a cathode according to an embodiment of the present disclosure.
Figure 4 shows an EDX analysis image of the cathode according to Comparative Example 2.
5 shows an SEM image of a cathode according to an embodiment of the present disclosure.
Figure 6 shows a SEM picture of the cathode according to Comparative Example 2.

Hereinafter, preferred embodiments of the present application will be described. However, embodiments of the present application may be modified in various other forms, and the scope of the present application is not limited to the embodiments described below. In addition, the embodiments of the present application are provided to more completely describe the present application to those skilled in the art.

In the present specification, when a part "includes" a certain component, this means that it may further include other components, without excluding other components, unless specifically stated otherwise.

In this specification, when a member is located "on" another member, this includes not only when one member is in contact with another member but also when another member exists between the two members.

In the present specification, "about" may mean an exact quantity. For example, "about 5 percent" means "about 5 percent" and / or "5 percent." "About" means within the usual experimental error for the application or intended purpose.

In general, the cathode of the solid oxide fuel cell is a perovskite material of ABO ₃ structure is used. As the cation, the larger one is represented by A, and the smaller one is represented by B. The A and the oxygen O form a face centered cubic structure, and B occupies an octahedral site therein. BCFZY0.1 (BaCo _0.4 Fe _0.4 Zr _0.1 Y _0.1 O _3-x ) in the perovskite material has a low activation energy compared to commonly known materials used as the cathode composition of solid oxide fuel cells. Accordingly, when the BCFZY0.1 is applied to a solid oxide fuel cell, it is possible to solve the problem of battery performance reduction due to polarization loss at low temperature, and thus high performance can be expected even at a driving temperature of 600 ° C. or lower. However, when the solid oxide fuel cell including the BCFZY0.1 is operated at more than 600 and less than 700 ℃, specifically 650 ℃, the actual performance of the fuel cell is very low, which may be due to low electrical conductivity.

According to the present specification, a solid oxide fuel cell cathode composition comprising a compound represented by the following formula (1) and a compound represented by the following formula (2) is used in a solid oxide fuel cell, so that a temperature range of more than 600 and 700 ° C or less, specifically, When the solid oxide fuel cell is driven at 650 ° C., while maintaining the actual performance of the fuel cell properly, durability is maintained when driving for a long time.

In the case of including the compound represented by the following formula (1), it has a stable cubic (cubic) structure and does not contain strontium (Sr free) composition because when applied to the mixed composition lowers the content of strontium (Sr) in terms of durability Do. This is a perovskite material of ABO ₃ structure, in the case of the cathode composition containing strontium (Sr) at the A site, there is a problem of the generation of secondary phase by strontium (Sr) segregation, This is because when the fuel cell is driven for a long time, it causes a decrease in performance.

In addition, the long-term operation of the fuel cell can alleviate the decrease in the actual performance of the fuel cell due to the coarsening phenomenon of the compound represented by the formula (2).

In addition, the compound represented by the following Chemical Formula 2 is a cathode material having high electrical conductivity, and when the compound represented by the following Chemical Formula 2 is included in the cathode composition for a solid oxide fuel cell, the low electrical conductivity characteristics of the compound represented by the following Chemical Formula 1 As a result, the actual performance of the fuel cell can be maintained relatively high.

An exemplary embodiment of the present specification provides a cathode composition for a solid oxide fuel cell comprising a compound represented by Formula 1 and a compound represented by Formula 2.

[Formula 1]

BaCo _0.4 Fe _0.4 Zr _0.2-x1 Y _x1 O _3-δ

[Formula 2]

La _1-x2 Sr _x2 CoO _3-δ

In Chemical Formula 1 and Chemical Formula 2,

0 ≦ x1 ≦ 0.2, 0 ≦ x2 <1, and δ is 0 or more and 0.3 or less.

An exemplary embodiment of the present specification provides a cathode composition for a solid oxide fuel cell in which the weight ratio of the compound represented by Chemical Formula 1 and the compound represented by Chemical Formula 2 is 10: 1 to 1:10.

Specifically, the weight ratio may be 2: 1 to 1: 2. More specifically, the weight ratio may be 1: 1. When the weight ratio satisfies the above range, the fuel cell cathode including the solid oxide fuel cell cathode composition may have excellent seal performance.

In one embodiment of the present specification, the compound represented by Chemical Formula 1 and the compound represented by Chemical Formula 2 included in the cathode composition for a solid oxide fuel cell may exist in a uniformly mixed composite form.

One embodiment of the present specification provides a cathode composition for a solid oxide fuel cell having an OPD (Operation Power Density) value of 0.28 W / cm ² or more.

The OPD value means a measure for evaluating the actual performance of the battery. The higher the OPD value is, the better it is, so the upper limit of the OPD value is not limited.

When the OPD value is 0.28 W / cm ² or more, since the actual performance of the fuel cell is high, a large amount of cells are not required to produce a target output performance when manufacturing a stack of the fuel cell, and thus there is an advantage in terms of cost.

The OPD value can be measured by the method described later. A 3 x 3 cm ² size cell is fabricated and current-voltage analysis is performed in a fuel cell evaluation system. Specifically, a nickel oxide (NiO) paste is applied to the fuel electrode of the cell, and a nickel mesh is used as a current collector to the anode and the air electrode rib of the metal jig to fix the cell. ) And silver mesh. The solid oxide fuel cell is pressurized and sealed using a sealant material containing glass powder. Current-Voltage analysis is performed at 650 ° C with 125 ml / min of hydrogen containing 3 to 4 wt% of moisture at the anode and 500 ml / min of air at the cathode, respectively, at operating temperature. can do. Thereafter, a current collector and a voltage wire may be connected to a metal jig, and current-voltage may be measured using an electric loader (model name: PLZ70UA, KIKUSUI, Japan).

According to an exemplary embodiment of the present specification, the ratio of the average atomic percent (at%) of lanthanum (La) and strontium (Sr) detected at the surface of the cathode by energy dispersive x-ray (EDX) analysis is 3: 1 to 6: Provided is a cathode for a solid oxide fuel cell.

Preferably, the ratio of the average atomic percent (at%) of the lanthanum (La) and strontium (Sr) may be 3: 1 to 4: 1.

More preferably, the average atomic percent (at%) ratio of the lanthanum (La) and strontium (Sr) may be 3: 1 to 3.04: 1.

When the fuel cell is driven for a long time by satisfying the range of the above average atomic percentage ratio, the durability of the fuel cell can be maintained by appropriately maintaining the content of strontium (Sr) that causes performance degradation. When a large amount of strontium is included in the cathode composition for a solid oxide fuel cell, a non-conductor strontium compound may be generated due to segregation of strontium when the fuel cell is driven for a long time. As a result, the porosity of the cathode is reduced, and secondary phase precipitation may occur at grain boundaries, which may cause degradation of a solid oxide fuel cell. However, the cathode composition for a solid oxide fuel cell according to an exemplary embodiment of the present specification includes a strontium content as appropriate, thereby maintaining the actual performance of the fuel cell and improving durability.

The energy dispersive x-ray (EDX) analysis refers to a method of characterizing a material by analyzing energy spectra of protruding electrons when X-rays are reflected on a sample. In the present specification, the EDX analysis may be used to determine an average content of atoms detected on the surface of the cathode, for example, an average content of lanthanum (La) and strontium (Sr).

SEM equipment for the EDX analysis may be used Hitachi TM3030Plus, EDX detector SwiftED3000 of Oxford instruments, but is not limited thereto. Specifically, the cell of the cathode according to the exemplary embodiment of the present specification is driven for 50 hours to analyze an area in which the random area of the cathode cell is enlarged at 6000 magnification.

The “average” means a value obtained by driving 1 to 10 times, preferably 5 times, under the above-described conditions using the EDX analysis.

An exemplary embodiment of the present specification provides a cathode for a solid oxide fuel cell including the cathode composition for the solid oxide fuel cell.

The cathode has a porous structure and may have a thickness of about 10 μm to about 60 μm. Preferably the thickness may be 30 to 40 ㎛.

When the thickness satisfies the above range, it is easy to manufacture by a wet process such as a screen printing method and a reaction area required for oxygen reduction can be secured. In addition, since the movement distance of the oxygen ions is shortened, it is possible to prevent the surface resistance of the air electrode from increasing.

An exemplary embodiment of the present specification provides a cathode composition for a solid oxide fuel cell, wherein the cathode composition for a solid oxide fuel cell is in a powder state.

An exemplary embodiment of the present specification comprises the steps of synthesizing the compound represented by Formula 1 and the compound represented by Formula 2, respectively, using a solid phase synthesis method; And preparing a cathode composition for a solid oxide fuel cell by mixing the compound represented by Formula 1 and the compound represented by Formula 2 synthesized by the synthesizing step. Provide a method.

Another embodiment of the present specification comprises the steps of synthesizing the compound represented by Formula 1 and the compound represented by Formula 2, respectively, using a solid phase synthesis method; And preparing a cathode composition for a solid oxide fuel cell in a powder state by mixing the compound represented by Formula 1 and the compound represented by Formula 2 synthesized by the synthesizing step. Provided are methods for preparing the composition.

The solid state reaction is a method in which a new compound is synthesized by a solid phase reaction by a temperature or pressure after the finely pulverized metal powder by a mechanical grinding method, the material mixed in a pure solid state by a solid phase reaction to be.

Synthesizing the compound represented by Chemical Formula 1 using the solid phase synthesis method weighs the raw powders of BaCO ₃ , Co ₃ O ₄ , Fe ₂ O ₃ , ZrO ₂ and Y ₂ O _{3 according} to stoichiometry, The wet-ball-milling may be performed and the solid phase reaction may be performed at a high temperature to prepare a particle powder. The high temperature means 900 to 1,100 ℃. An element ratio of Ba: Co: Fe: Zr: Y included in the compound represented by Chemical Formula 1 may be 1.0: 0.4: 0.4: 0.1: 0.1.

Synthesizing the compound represented by Chemical Formula 2 by using the solid phase synthesis method weighs La ₂ O ₃ , Sr (CO ₃ ) and Co ₃ O ₄ raw powders in accordance with stoichiometry, and then wet-ball-milling. It may mean that the particle powder is produced by performing a solid phase reaction at a high temperature. An element ratio of La: Sr: Co included in the compound represented by Formula 2 may mean 0.6: 0.4: 1 or 0.8: 0.2: 1. Preferably, the element ratio of La: Sr: Co included in the compound represented by Formula 2 may be 0.8: 0.2: 1.

Synthesizing the compound represented by Chemical Formula 1 and the compound represented by Chemical Formula 2 by using the solid phase synthesis method may include mixing raw materials, milling, drying and calcining. .

In the mixing of the raw material powder, the raw material powder may be mixed in a solvent.

In the step of mixing the raw material powder, the raw material powder and the solvent may be added to a ball mill (ball mill) container. The material or type of the ball mill container is not particularly limited, and may be, for example, a container made of polyethylene (PE).

The solvent is not particularly limited as long as the material is easy to disperse, dry and remove the raw material powder, and conventional materials known in the art may be used.

For example, the solvent may be at least one selected from the group consisting of water, iso propanol, toluene, ethanol, n-propanol, n-butyl acetate, ethylene glycol, butyl carbitol and butyl carbitol acetate. It can be used, preferably water or ethanol can be used.

The milling step is a process for physically mixing the raw material powder and the solvent mixed in the step of mixing the raw material powder, it may be mixed for 5 hours to 30 hours at 100rpm to 500rpm. At this time, zirconia balls having a diameter of 3 mm, 5 mm, 10 mm or 15 mm may be used.

In addition, the drying may be performed after milling the raw powder. The drying step is a process for drying the raw material powder in a liquid state together with the solvent to make a solid state, it may be performed for 5 to 24 hours at a temperature of 90 ℃ to 200 ℃ in a circulation dryer.

In addition, the calcining may be performed after the drying. The calcining step is to carry out a heat treatment process for burning the organic material and causing a solid phase reaction to become the solid state obtained in the drying step. The rate of temperature increase and decrease may be calcined while maintaining for 1 hour to 20 hours or 3 hours to 10 hours at 900 ° C to 1200 ° C at a temperature of 3 ° C / min to 5 ° C / min. Thus, the compound represented by Formula 1 and the compound represented by Formula 2 can be synthesized.

If necessary, the step of synthesizing the compound represented by Formula 1 and the compound represented by Formula 2 using the solid phase synthesis method may further include remilling.

The remilling is a process for further controlling the particle size of the powder. The method is not particularly limited, but may include a ball mill, jet mill, bead mill, or attrition mill process.

The particle size of the powder after the re-milling step may be 0.1 to 5㎛, the particle size of the powder obtained according to the type of the process may be different. When the particle size of the powder is in the above range, it is easy to manufacture a paste including a cathode composition for a solid oxide fuel cell to be described later, and there is an effect of securing a reaction area necessary for an oxygen reduction reaction.

The ball mill is the same as the method for mixing the raw powder.

The jet mill is a method of grinding the powder by rotating the disk at the pressure of the compressed air.

The bead mill is a method of pulverizing the beads (bead) in the chamber by the rotational force and centrifugal force, it is possible to obtain smaller particles than the jet mill. At this time, by adjusting the speed of the bead mill chamber or the pump injection speed, it is possible to obtain powder particles of a smaller size.

The remilling step may be milling after dispersing the powder in water or ethanol.

In the step of preparing a cathode composition for a solid oxide fuel cell in a powder state by mixing the compound represented by Formula 1 and the compound represented by Formula 2 synthesized by the synthesizing step, the "mixing" is a blender mixer ( may be performed in a dry state using a blender mixer.

In an exemplary embodiment of the present specification, the cathode composition may be prepared using the method for preparing a cathode composition for a solid oxide fuel cell.

By using the prepared cathode composition, a cathode for a solid oxide fuel cell may be manufactured.

Preparing a cathode composition for the solid oxide fuel cell, and then preparing a paste including the prepared cathode composition to manufacture the cathode for the solid oxide fuel cell; Depositing the paste over the planar cell; And heat treatment.

The flat cell means an anode and an electrolyte layer.

According to the exemplary embodiment of the present specification, the preparing of the paste including the prepared cathode composition may be performed by dispersing and mixing the powder in a dispersion solvent to which a dispersant is added, and then adding and mixing a binder and a plasticizer. It may be.

The preparing of the paste is a process for mixing various additives by pretreatment before coating the powder on the flat cell.

The additive may further include at least one of a binder, a plasticizer, and a dispersant. The binder, plasticizer and dispersant are not particularly limited, and conventional materials well known in the art may be used.

The binder may be at least one of a copolymer of poly (butyl methacrylate) -poly (2-ethylhexyl methacrylate) (PBMA-PEHMA), ethyl cellulose (EC), polyvinylisobutyral (PViB), and poly 2-ethylhexylacrylate (PEHA). .

The binder content is 20% by weight to 35% by weight based on the total weight of the paste.

When the content of the binder satisfies the above range, a paste having an easy viscosity for screen printing may be manufactured and effects such as peeling off during cell sintering and securing sufficient porosity may be obtained.

The plasticizer may be at least one of DBP (Di-butyl-phthalate), DOP (Di-2-ethylhexyl phthalate), DINP (Di-isononyl phthalate), DIDP (Di-isodecyl phthalate) and BBP (Butyl benzyl phthalate). .

The amount of the plasticizer may be 3 wt% or more and 7 wt% or less based on the total weight of the paste.

The dispersant is not particularly limited as long as it is known in the art, and may be, for example, di-butyl-phthalate (DBP).

The content of the dispersant may be 0.5% by weight or more and 2% by weight or less based on the total weight of the paste. When the dispersant is within the above range, it may be easy to manufacture a paste comprising the cathode composition.

The dispersion solvent is not particularly limited as long as it is a material that disperses the raw material powder and is easy to remove after preparing the paste, and conventional materials known in the art may be used.

For example, the dispersion solvent may be at least one selected from the group consisting of water, iso propanol, toluene, ethanol, n-propanol, n-butyl acetate, ethylene glycol, butyl carbitol and butyl carbitol acetate. May be used, and preferably butyl carbitol may be used.

The content of the dispersion solvent may be 5 wt% or more and 15 wt% or less based on the total weight of the paste. When the above range is satisfied, the raw material powder may be well dispersed, and the solvent may be smoothly dried in the process of drying the solvent.

According to the exemplary embodiment of the present specification, the depositing of the paste on the flat cell may include coating the paste on the flat cell by using screen printing.

According to one embodiment of the present specification, the heat treatment may be performed for 1 hour to 10 hours at an execution temperature of 800 ° C to 1100 ° C. When the above range is satisfied, the density of the coated paste may be excellent and durability may be increased.

One embodiment of the present specification is the cathode; Anode; And it provides a solid oxide fuel cell comprising an electrolyte layer provided between the cathode and the anode.

FIG. 1 schematically illustrates the principle of electricity generation of a solid oxide fuel cell. The solid oxide fuel cell includes an electrolyte layer, an anode, and a cathode formed on both surfaces of the electrolyte layer. do. Referring to FIG. 1, which illustrates electricity generation principle of a solid oxide fuel cell, oxygen ions are generated as air is electrochemically reduced in a cathode, and the generated oxygen ions are transferred to an anode through an electrolyte layer. In the anode, fuels such as hydrogen, methanol, butane, etc. are injected, and the fuel combines with oxygen ions to oxidize electrochemically, producing electrons and producing water. This reaction causes the movement of electrons in the external circuit.

Figure 2 shows a state of the cathode for a solid oxide fuel cell according to an embodiment of the present specification, it can be confirmed that the cathode having a thickness of 10 to 60㎛.

FIG. 3 is a surface photograph after driving an evaluation cell of a cathode for a solid oxide fuel cell according to one embodiment of the present specification for 50 hours, and shows an image of an energy dispersive x-ray (EDX) analysis. The average atomic percent (at%) ratio of lanthanum (La) and strontium (Sr) detected on the surface of the cathode according to one embodiment of the present specification by EDX analysis is 3: 1 to 6 : 1, by satisfying the above range, the content of strontium is properly included in the cathode composition for a solid oxide fuel cell according to an exemplary embodiment of the present specification, there is an advantage of maintaining the actual performance and durability of the fuel cell.

FIG. 4 is an EDX analysis image as a surface photograph after driving a cathode evaluation cell for a solid oxide fuel cell according to Comparative Example 2 for 50 hours. Energy dispersive x-ray (EDX) analysis showed that the average atomic percent (at%) ratio of lanthanum (La) and strontium (Sr) detected on the surface of the cathode according to Comparative Example 2 ranges from 6: 4 to 6: 5 By being in the above range, secondary phase generation by strontium (Sr) segregation can be observed.

5 is a scanning electron microscope (SEM) photograph after driving an evaluation cell of a cathode for a solid oxide fuel cell according to an exemplary embodiment of the present specification for 50 hours, and it cannot be observed that strontium (Sr) is segregated. .

FIG. 6 is a scanning electron microscope (SEM) photograph after driving an evaluation cell of a cathode for a solid oxide fuel cell according to Comparative Example 2 for 50 hours, in which strontium (Sr) is segregated over the entire area of the evaluation cell and is secondary. It can be seen that a phase is formed.

In an exemplary embodiment of the present specification, in addition to the cathode, a method of manufacturing an anode and an electrolyte layer may use materials and methods known in the art.

The anode may include an inorganic material having oxygen ion conductivity, so that the anode may be applied to the anode for a solid oxide fuel cell. The type of the inorganic material is not particularly limited, but the inorganic material is yttria stabilized zirconium oxide (zirconia) (YSZ: (Y ₂ O ₃ ) _x (ZrO ₂ ) _1-x , x = 0.05 to 0.15), Scandia Stabilized zirconium oxide (ScSZ: (Sc ₂ O ₃ ) _x (ZrO ₂ ) _1-x , x = 0.05 to 0.15), samarium dope ceria (SDC: (Sm ₂ O ₃ ) _x (CeO ₂ ) _{1- x} , x = 0.02 to 0.4) and gadolinium dope ceria (GDC: (Gd ₂ O ₃ ) _x (CeO ₂ ) _1-x , x = 0.02 to 0.4).

The thickness of the anode may be 10 ㎛ to 1,000 ㎛. Specifically, the thickness of the anode may be 100 ㎛ to 800 ㎛.

The porosity of the anode may be 10% to 50%. Specifically, the porosity of the anode may be 10% to 30%.

The pore diameter of the anode may be 0.1 ㎛ to 10 ㎛. Specifically, the diameter of the pores of the anode may be 0.5 ㎛ to 5 ㎛. More specifically, the diameter of the pores of the anode may be 0.5 ㎛ to 2 ㎛.

The manufacturing method of the anode is not particularly limited, for example, by coating the slurry for the anode and drying and baking it, or coating the anode slurry on a separate release paper and dried to prepare a green sheet for the anode, at least one anode The green sheet may be calcined alone or with the green sheet of a neighboring layer to produce an anode.

The anode green sheet may have a thickness of about 10 μm to about 500 μm.

The anode slurry includes inorganic particles having oxygen ion conductivity, and if necessary, the anode slurry may further include at least one of a binder resin, a plasticizer, a dispersant, and a solvent, and the binder resin, a plasticizer, a dispersant, and The solvent is not particularly limited, and conventional materials known in the art may be used.

Based on the total weight of the slurry for the anode, the content of the inorganic particles having the oxygen ion conductivity is 10% to 30% by weight, the content of the solvent is 10% to 30% by weight, the content of the dispersant is 5% by weight % To 10% by weight, a plasticizer content of 0.5% to 3% by weight, and a binder content of 10% to 30% by weight.

The anode slurry may further include NiO. Based on the total weight of the slurry for the anode, the content of NiO may be 10% by weight to 30% by weight.

The anode may be provided on a separate porous ceramic support or a porous metal support, or may include an anode support and an anode functional layer. In this case, the anode support is a layer including the same inorganic material as the anode functional layer but having a higher porosity and relatively thicker thickness than the anode functional layer to support another layer, and the anode functional layer is provided between the anode support and the electrolyte layer. It may be a floor that plays a major role as an actual anode.

When the anode is provided on the porous ceramic support or the porous metal support, the anode may be manufactured by laminating the manufactured green sheet for the anode on the fired porous ceramic support or the porous metal support and then firing it.

When the anode includes an anode support and an anode functional layer, an anode may be manufactured by laminating the manufactured green sheet for the anode functional layer on the fired anode support and then firing it.

When the anode includes an anode support and an anode functional layer, the thickness of the anode support may be 350 μm to 1,000 μm, and the thickness of the anode function layer may be 5 μm to 50 μm.

In addition, in an exemplary embodiment of the present specification, the electrolyte layer may include an oxygen ion conductive inorganic material, and is not particularly limited as long as it has oxygen ion conductivity.

Specifically, the oxygen ion conductive inorganic material of the electrolyte layer may include a composite metal oxide including one or more selected from the group consisting of zirconium oxide based, cerium oxide based, lanthanum oxide based, titanium oxide based and bismuth oxide based materials. Can be. More specifically, the oxygen ion conductive inorganic material of the electrolyte layer is yttria stabilized zirconium oxide (zirconia) (YSZ: (Y ₂ O ₃ ) _x (ZrO ₂ ) _1-x , x = 0.05 ~ 0.15), Scandia Stabilized zirconium oxide (ScSZ: (Sc ₂ O ₃ ) x (ZrO ₂ ) _1-x , x = 0.05 to 0.15), samarium dope ceria (SDC: (Sm ₂ O ₃ ) x (CeO ₂ ) 1- x, x = 0.02 to 0.4) and gadolinium dope ceria (GDC: (Gd ₂ O ₃ ) x (CeO ₂ ) 1-x, x = 0.02 to 0.4).

The electrolyte layer may have a thickness of about 10 μm to about 100 μm. Specifically, the thickness of the electrolyte layer may be 20 ㎛ to 50 ㎛.

The manufacturing method of the electrolyte layer is not particularly limited, for example, by coating the slurry for the electrolyte layer and drying and baking it, or by coating and drying the electrolyte layer slurry on a separate release paper to prepare an electrolyte layer green sheet, the electrolyte The layer green sheet may be calcined alone or with the green sheet of the neighboring layer to prepare an electrolyte layer.

The electrolyte sheet green sheet may have a thickness of about 10 μm to about 100 μm.

The slurry for the electrolyte layer includes inorganic particles having oxygen ion conductivity, and the electrolyte layer slurry may further include at least one of a binder resin, a plasticizer, a dispersant, and a solvent, if necessary, and the binder resin, a plasticizer, a dispersant, and The solvent is not particularly limited, and conventional materials known in the art may be used.

Based on the total weight of the slurry for the electrolyte layer, the content of the inorganic particles having oxygen ion conductivity may be 40 wt% to 70 wt%.

Based on the total weight of the slurry for the electrolyte layer, the solvent content is 10 wt% to 30 wt%, the dispersant content is 5 wt% to 10 wt%, the plasticizer content is 0.5 wt% to 3 wt%, and the binder The content of may be 10% to 30% by weight.

In the present specification, the green sheet refers to a film in the form of a film that can be processed in the next step, not a complete final product. In other words, the green sheet is coated with a coating composition containing inorganic particles and a solvent and dried in a sheet form, and the green sheet refers to a sheet in a semi-dried state that can maintain a sheet form while containing some solvent.

The shape of the fuel cell is not limited, and may be, for example, coin, flat, cylindrical, horn, button, sheet or stacked.

Specifically, the fuel cell may be used as a power source for an electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, or a power storage device.

Hereinafter, the present specification will be described in more detail with reference to Examples. However, the following examples are merely to illustrate the present specification, but not to limit the present specification.

<Example>

1. Preparation of cathode composition for solid oxide fuel cell

Example 1 Powder Composition 1

Storing powders of BaCO ₃ , Co ₃ O ₄ , Fe ₂ O ₃ , ZrO ₂ and Y ₂ O ₃ were stoichiometrically followed by wet-ball-milling and solid phase reaction at high temperature (1,000 ° C.). It was carried out to prepare a particle powder of the compound represented by the formula (1). The element ratio of Ba: Co: Fe: Zr: Y included in the compound represented by Formula 1 was 1.0: 0.4: 0.4: 0.1: 0.1.

Thereafter, La ₂ O ₃ , Sr (CO ₃ ) and Co ₃ O ₄ raw powders were weighed according to stoichiometry, followed by wet-ball-milling, and a solid phase reaction at a high temperature (1,000 ° C.). Particle powder of the compound represented by 2 was prepared. The element ratio of La: Sr: Co contained in the compound represented by the following formula (2) was 0.8: 0.2: 1.

After the weight ratio of the prepared particle powder of the compound represented by the formula (1) and the particle powder of the compound represented by the formula (2) is 1: 1, and added to a stainless steel container of the blender mixer (Blender mixer), Stirred for 1 minute.

[Formula 1]

BaCo _0.4 Fe _0.4 Zr _0.2-x1 Y _x1 O _3-δ

[Formula 2]

La _1-x2 Sr _x2 CoO _3-δ

In Chemical Formula 1 and Chemical Formula 2,

0 ≦ x1 ≦ 0.2, 0 ≦ x2 <1, and δ is 0 or more and 0.3 or less.

Thus, the cathode composition 1 for the solid oxide fuel blocking in the powder state was prepared.

2. Preparation of Paste Containing Cathode Composition for Solid Oxide Fuel Cell

Example 1 Paste Composition 1

Cathode composition 1 for the solid oxide fuel cell prepared above, ethyl cellulose (Ethyl cellulose) as a binder and butyl carbitol as a dispersion solvent was mixed, and the plasticizer dibutyl phthalate (DBP) was added After that, the mixture was mixed at a speed of 2000 rpm using a paste mixer to form a paste primarily.

The first formed paste was mixed and pulverized three times using a 3 roll milling equipment to finally prepare a paste composition 1 including the oxide powder 1.

The weight% of the powder composition 1, the binder, the dispersion solvent, and the plasticizer to the total weight of the prepared paste composition 1 are shown in Table 1 below.

ingredient Kinds Content (% by weight) Paste Composition 1 Powder Composition 1 - 54.71 bookbinder Ethyl cellulose 30.03 Dispersing solvent Butyl Carbitol 10.18 Plasticizer Dibutyl phthalate 5.09

3. Fabrication of cathode for solid oxide fuel cell

The paste composition 1 was coated on the flat plate cell (including the anode and the electrolyte layer) by using screen printing.

Thereafter, the solvent was removed in a circulation dryer at a temperature of 100 ° C. Thereafter, a cathode having a thickness of 35 μm was prepared by heat treatment at a temperature of 1100 ° C. for 2 hours, and the appearance of the cathode is shown in FIG. 2.

4. Manufacturing of evaluation cell

The prepared 3 × 3 cm ² size cells were tested for IV characteristics in a fuel cell evaluation system.

NiO paste (Anode Contact paste) was applied to the cell's anode, and nickel mesh and silver mesh were used as current collectors on the anode and cathode rib of the metal jig to fix the cell. Was attached. Thereafter, the solid oxide fuel cell was pressurized and sealed using a sealant material including glass powder, thereby preparing an evaluation cell.

Comparative Example

(Comparative Example 1)

In Example 1, except for the particle powder of the compound represented by Formula 1 and the particle powder of the compound represented by Formula 2, except that only the particle powder of the compound represented by Formula 1 as a cathode composition In the same manner as in Example 1, a cathode and an evaluation cell for a solid oxide fuel cell were manufactured.

(Comparative Example 2)

In Example 1, except that the particle powder of the compound represented by the formula (2) instead of the particle powder of the compound represented by the formula (1) and the particle powder of the compound represented by the formula (2) as the cathode composition In the same manner as in Example 1, a cathode and an evaluation cell for a solid oxide fuel cell were manufactured. The element ratio of La: Sr: Co included in the compound represented by Formula 2 was 0.8: 0.2: 1.

Experimental Example

One. Cell performance measurement

IV characteristics were tested in a fuel cell evaluation system with the evaluation cells of the examples and comparative examples being 3 × 3 cm ² .

Current-Voltage analysis provides 650 mL / min of hydrogen (H ₂ ) containing 3-4% moisture at the anode and 500 mL / min of air at the cathode, respectively, at operating temperature. Measurement was made at the driving temperature.

The current collector and the voltage line were connected to the metal jig, and the current-voltage was measured using an electric loader (Model: PLZ70UA, KIKUSUI, Japan), and the results are shown in Table 2 below. .

Battery performance evaluation:
OPD (W / cm ² ) Example 1 0.284 Comparative Example 1 0.200

According to Table 2, the OPD value of Example 1 was higher than the OPD value of Comparative Example 1, it was confirmed that the solid oxide fuel cell seal performance according to Example 1 is excellent.

2. Durability rating

After the heat treatment of the evaluation cell of the fuel cell according to the Examples and Comparative Examples for 50 hours at 650 ℃ driving temperature, the lanthanum (La) and strontium (La) detected on the surface of the cathode by the energy dispersive x-ray (EDX) analysis The average atomic percent (at%) of Sr) was measured.

Specifically, the SEM 30 for EDX analysis was used as a TM3030Plus manufactured by Hitachi, and the SwiftED3000 system of Oxford instruments as an EDX detector, and an area where the random region of the cathode cell was magnified at 6000 magnification was analyzed.

The results are shown in Table 3 below.

Cathode composition
(Based on 100 wt% of the cathode composition) Lanthanum (La) average atomic percent (at%) Strontium (Sr) Average Atomic Percent (at%) Example 1 50% by weight of the compound represented by Formula 1 + 50% by weight of the composition represented by Formula 2 75.24 24.76 Comparative Example 2 100% by weight of the compound represented by formula (2) 61.73 38.27

According to Table 3, the ratio of the average atomic percent (at%) of lanthanum (La) and strontium (Sr) detected on the surface of the cathode prepared from the cathode composition according to Example 1 is about 3: 1, Comparative Example 2 The average atomic percent (at%) ratio of lanthanum (La) and strontium (Sr) detected on the cathode surface prepared with the cathode composition according to Example 6 was about 6: 4, and thus the amount of strontium detected on the cathode surface according to Example 1 It was confirmed that it was less than the thing of this comparative example 1, and was close to 4: 1 which is a theoretical ratio.

As a result, the long-term operation of the solid oxide fuel cell including the cathode prepared by using the cathode composition according to an exemplary embodiment of the present disclosure can suppress the secondary phase generation problem due to excessive content of strontium, it was confirmed that the durability is improved. .

As confirmed in Table 2 and Table 3, when the fuel cell including the solid oxide fuel cell cathode according to one embodiment of the present specification is operated at low to low temperatures (above 600 ° C. and less than 700 ° C.), excellent performance is maintained while maintaining actual performance. It was confirmed that stable battery operation was possible due to the durability.

Although the preferred embodiment of the present invention has been described above, the present invention is not limited thereto, and various modifications and changes can be made within the scope of the claims and the detailed description of the invention, which also belong to the scope of the invention. .

Claims (8)

A cathode composition for a solid oxide fuel cell comprising a compound represented by Formula 1 and a compound represented by Formula 2 below:
[Formula 1]
BaCo _0.4 Fe _0.4 Zr _0.2-x1 Y _x1 O _3-δ
[Formula 2]
La _1-x2 Sr _x2 CoO _3-δ
In Chemical Formula 1 and Chemical Formula 2,
0 ≦ x1 ≦ 0.2, 0 ≦ x2 <1, and δ is 0 or more and 0.3 or less. The cathode composition of claim 1, wherein a weight ratio of the compound represented by Chemical Formula 1 and the compound represented by Chemical Formula 2 is 10: 1 to 1:10. The cathode composition of claim 1, wherein an OPD (Operation Power Density) value is 0.28 W / cm ² or more. The cathode composition of claim 1, wherein the cathode composition for a solid oxide fuel cell is in a powder state. A cathode for a solid oxide fuel cell comprising the cathode composition for a solid oxide fuel cell according to any one of claims 1 to 4. The method according to claim 5, wherein the average atomic percentage (at%) ratio of lanthanum (La) and strontium (Sr) detected on the surface of the cathode by energy dispersive x-ray (EDX) analysis is 3: 1 to 6: 1 The cathode for a solid oxide fuel cell. Synthesizing the compound represented by the following Chemical Formula 1 and the compound represented by the following Chemical Formula 2 using the solid phase synthesis method; And preparing a cathode composition for a solid oxide fuel cell by mixing the compound represented by the following Chemical Formula 1 and the compound represented by the following Chemical Formula 2 synthesized by the synthesizing step: Method for producing a cathode composition for a solid oxide fuel cell according to:
[Formula 1]
BaCo _0.4 Fe _0.4 Zr _0.2-x1 Y _x1 O _3-δ
[Formula 2]
La _1-x2 Sr _x2 CoO _3-δ
In Chemical Formula 1 and Chemical Formula 2,
0 ≦ x1 ≦ 0.2, 0 ≦ x2 <1, and δ is 0 or more and 0.3 or less. A cathode for a solid oxide fuel cell according to claim 5; Anode; And an electrolyte layer provided between the cathode and the anode.

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