KR101934006B1 - Solid oxide fuel cell and solid oxide electrolysis cell including Ni-YSZ fuel(hydrogen) electrode, and fabrication method thereof - Google Patents

Abstract

The present invention relates to a solid oxide fuel cell and an electrolytic cell in which a Ni (or NiO or less NiO) -YZZ fuel (hydrogen) electrode is used in a fuel cell (SOFC) And to improve cell performance while maintaining the cell performance. That is, in order to develop a fuel electrode support type cell having excellent cell performance in both modes of fuel cell and electrolysis, an electrolytic cell composed of a conventional Ni-YSZ fuel (hydrogen) electrode having excellent mechanical strength and a YSZ electrolyte is directly used The performance of the solid oxide fuel cell and the electrolytic cell can be improved by impregnating or infiltrating a suspension or a molten salt or a solution of a specific ceramic powder in order to improve the activity and stability of the electrode, (Hydrogen) electrode excellent in both performance and performance, and an electrolytic cell.
The present invention is based on the premise that a Ni-YSZ fuel (hydrogen) electrode is impregnated with a ceramic powder suspension of Gd ₂ O ₃ or Sm ₂ O ₃ (or a suspension of Gd-doped ceria (GDC) or Sm-doped ceria (SDC) powder) As an equivalent effect, Gd salt (salt, eg nitrate) and Sm salt (salt, eg nitrate) are dissolved (or melted and dissolved) in the solution to impregnate or infiltrate the fuel Followed by subsequent heat treatment or simultaneous sintering.
According to the present invention, the manufacturing time and process of the solid oxide fuel cell and the electrolytic cell can be shortened, and the cost required for manufacturing the cell can be reduced. In addition, YSZ-based electrolytes and fuel (hydrogen) electrodes are able to compensate for the performance degradation of ceria-based electrolytes and fuel (hydrogen) electrodes compared to ceria-based electrodes while overcoming the weakness of mechanical strength. Therefore, the Ni-YSZ fuel (hydrogen) electrode layer impregnated with the Gd component or the Sm component is stable in both the solid oxide fuel cell mode for electric production and the solid oxide electrolytic cell mode for producing hydrogen and hydrocarbons by steam electrolysis or carbon dioxide electrolysis High performance and high durability.

Description

Technical Field [0001] The present invention relates to a solid oxide fuel cell including a Ni-YSZ fuel (hydrogen) electrode, an electrolytic cell and a manufacturing method thereof,

The present invention relates to solid oxide fuel cells and electrolytic cells and the production method thereof, and more particularly, NiO-YSZ (Operating Sikkim reduced to Ni, less than Ni-YSZ represented by) fuel Gd ₂ O ₃ in (hydrogen) electrode Or a Sm ₂ O ₃ ceramic powder suspension (or suspension of Gd-doped ceria (GDC) or Sm-doped ceria (SDC) powder) or equivalent effect of Gd salt (or hydrogen sulfide) impregnation or infiltration in a solution (or molten solution) in a solution (water), and then the unit cell is subjected to heat treatment or in-situ sintering in advance, The present invention relates to a solid oxide fuel cell, an electrolytic cell, and a method of manufacturing the same.

Humans are facing serious environmental problems, such as global warming caused by greenhouse gases, due to the large use of fossil fuels, which has a decisive influence on human survival. Hydrogen is a clean energy that does not emit greenhouse gases. Since hydrogen can be produced from unlimited water on the planet, it can fundamentally solve problems such as depletion of energy resources based on fossil fuels and greenhouse gas emissions. It has been recognized as an alternative energy resource.

However, since most of the hydrogen currently produced is made from hydrocarbons, it has the disadvantage of generating carbon dioxide and consuming fossil fuels. High temperature electrolysis (HTE) Hydrogen or Hydrocarbon production process, which is one of the advantageous methods for solving these problems and producing large capacity hydrogen, can produce hydrogen directly from high temperature steam using electrolysis, It is a direct production method of hydrocarbons.

Solid Oxide Electrolysis Cell (SOEC) used for high temperature electrolysis is a very high temperature electrolyzer that not only produces hydrogen through water vapor (H ₂ O) electrolysis, but also CO2 (CO ₂ ) electrolysis (Hydrogen gas and carbon monoxide mixed gas) and hydrocarbons that can be used as fuel can be directly produced. As a result, green technology that can recycle carbon dioxide emitted from fossil fuels has attracted attention recently.

If electricity needed for this hydrogen production process can be obtained from renewable energy sources, this means that hydrogen production is possible without emission of greenhouse gases. In addition, using thermal power or waste heat from nuclear power plants or industrial sites not only increases energy efficiency, but also reduces hydrogen production costs. Electrolysis of water has an important advantage in that it can produce hydrogen at a high concentration without the need for additional steps such as removal of impurities. Since high-temperature electrolysis consumes less electricity than low-temperature electrolysis, the hydrogen production cost can be reduced by reducing the amount of electric energy required for hydrogen and hydrocarbon production, have.

On the other hand, such a high-temperature electrolytic apparatus can be applied as a high-efficiency clean shoe former technology which is a fuel cell capable of producing electricity from hydrogen or fuel when used as a reverse reaction thereof. When this technology is used, The emission of carbon dioxide can be reduced to about 30% or more. Particularly, the use of only hydrogen, which is the clean fuel, has an advantage of completely suppressing the emission of carbon dioxide.

In a solid oxide electrolytic cell, a hydrogen (or fuel) electrode is an electrode in which a reaction occurs in which water vapor is reduced to hydrogen (or fuel). The oxygen electrode is an electrode where oxygen ions are oxidized to oxygen. The high operating temperature of the solid oxide electrolytic cell improves the reaction rate of the electrode, thereby reducing the resistance to the electrolysis reaction of the electrolytic cell (SOEC), thereby improving the performance of the cell.

The principle of high-temperature electrolysis is basically a reverse reaction process of a solid oxide fuel cell (SOFC), and a high-temperature electrolysis technique can share a technology with a fuel cell in many parts such as a device and an operating method. Can be used for the production of hydrogen and hydrocarbons as well as hydrogen (carbonization) production and fuel cell technology.

In particular, surplus power can be stored in hydrogen energy form through hydrogen production using high temperature electrolysis. In the case of peak load with insufficient power, it can be converted into solid oxide fuel cell function and produce electricity by consuming produced hydrogen and hydrocarbon fuel. Therefore, power storage and peak load control functions can maximize utilization of power facilities and prepare for the renewable energy duty allocation system (RPS) to be implemented in 2012.

The solid oxide fuel cell and the electrolytic cell are divided into a high-temperature type operating at about 800 to 1,000 ° C, a mesophilic type operating at 650 to 800 ° C and a low-temperature type operating at 650 ° C or less depending on the materials and applications to be used , And a fuel (hydrogen) electrode support type, an electrolyte support type, and a metal support type, depending on components that serve as a support for maintaining mechanical strength.

A planar solid oxide fuel cell having a dual fuel (hydrogen) electrode support structure and an electrolytic cell are formed by coating an electrolyte membrane having a very thin thickness (10 to 30 탆) on a fuel (hydrogen) electrode support, Not only is it possible to operate at lower temperatures (700 to 800 ° C), it also has the advantage of using cheap metal connectors (separator plates).

In general, a fuel (hydrogen) pole support type unit cell first forms a fuel (hydrogen) pole support, obtaining a pre-sintered body at a high temperature of about 1,200 to 1,450 ° C, And heat-treated at a temperature of about 1,250 ° C. Then, the electrolyte layer is coated and sintered simultaneously with the fuel (hydrogen) electrode at a high temperature of 1,500 ° C or higher. After that, an air electrode is coated on the electrolyte layer and heat treatment is performed to produce a unit cell.

The solid oxide fuel cell and the fuel (hydrogen) electrode of the electrolytic cell provide a site where the electrochemical reaction of the oxidation of the fuel and the reduction of water vapor (carbon dioxide) takes place. Noble metals such as platinum (Pt) and transition metals such as nickel (Ni) and cobalt (Co) are used as the material of the fuel (hydrogen) electrode. However, precious metal-based materials are not commonly used because of their high cost, and nickel (Ni) is widely used in fuel cells and hot electrolysis due to its high electrochemical reactivity at high temperatures. However, since nickel (Ni) has only electronic conductivity, in order to extend the electrochemical reaction at the interface between the electrode where the electrochemical reaction occurs and the electrolyte (TPB, triple phase boundary), nickel (Ni) It is used as an electrode by mixing with an electrolyte material having conductivity. This type of electrode is called a cermet (a mixture of ceramic and metal) electrode.

The electrolyte material is stabilized yttria based on the zirconia (ZrO ₂₎ zirconia (YSZ, yittria-stabilized zirconia), and a ceria-GDC that is based on a _{(CeO 2) (gadolinium-doped} CeO 2) or SDC (samarium-doped ceria) is mainly used.

In the solid oxide fuel cell and the cathode of the electrolytic cell, reduction of oxygen and oxidation of oxygen ions occur. As the electrode material, a mixed oxide of the perovskite structure of ABO ₃ type, which has the property of electron conduction, Typical cathode materials are lanthanum strontium manganate (LSM), lanthanum strontium cobaltite (LSC), lanthanum-strontium iron oxide (LSF), lanthanum strontium ferrite, And lanthanum-strontium-cobaltite (LSCF) lanthanum strontium cobaltite ferrite.

Generally, in a solid oxide fuel cell and an electrolytic cell manufactured by the same material and manufacturing method, cell performance in an electrolysis mode in which water vapor is electrolyzed to produce hydrogen (carbonized) It does not appear the same as the cell performance in the fuel cell (galvanic) mode. As described above, the cell performance in these two modes is highly dependent on the electrode material. In the case of the Ni-YSZ electrode used for the solid oxide fuel cell and the electrolytic cell, the electrochemical performance for the water vapor electrolysis is influenced by the performance Respectively. Therefore, when a unit cell having the same structure as that of the solid oxide fuel cell is used as the solid oxide electrolytic cell, the cell performance is deteriorated, which is disadvantageous from the viewpoint of efficiency.

In a recent study, it was reported that ceria-based materials such as Ni-GDC and Ni-SDC electrodes were relatively stable and high-performance measured in fuel cell and electrolysis mode. Therefore, if Ni-GDC composite electrode and GDC electrolyte or Ni-SDC composite electrode and SDC electrolyte are used as fuel (hydrogen) electrode, higher performance can be expected in fuel cell and electrolytic cell composed of Ni-YSZ electrode and YSZ electrolyte It will be possible.

However, since the ceria-based material has mixed conductivity, the open circuit voltage (OCV) of a cell having a ceria-based electrolyte is generally lower than the Nernst Voltage. In addition, the high voltage applied in the electrolysis system may not be suitable as an electrolyte for electrolysis since it can reduce the ion mobility coefficient by reducing Ce ^{4 +} to Ce ^{3 +} in the ceria electrolyte.

In addition, ceria based electrolytes have relatively low mechanical strengths than YSZ electrolytes. Therefore, Ni-GDC and Ni-SDC fuel (hydrogen) electrode support cells are not suitable for mechanical strength problems. In order to use a ceria-based electrolyte, a metal-supported fuel cell or an electrolytic cell capable of increasing the mechanical strength of the cell is suitable. However, in the case of electrolysis, since oxidation is carried out in an environment where the water vapor content is high, oxidation of the metal support is a problem, and it is practically difficult to use the electrolytic cell of the metal support type. Therefore, it is necessary to develop new materials that can improve the electrode performance while using YSZ as the electrolyte in the electrolytic cell.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems and to provide a method of manufacturing a fuel cell (SOFC) for producing electricity and a method for producing a hydrogen- And to provide a solid oxide fuel cell, an electrolytic cell and a method of manufacturing the solid oxide fuel cell.

Specifically, the object of the present invention is to overcome the disadvantage that the cerium (CeO ₂ ) -based fuel (hydrogen) electrode and the electrolyte which are excellent in the cell performance in both the fuel cell and the electrolysis mode are weak in the mechanical strength, (Hydrogen) electrode and YSZ electrolytic cell, which is superior to the existing Ni-YSZ fuel (hydrogen) electrode, can improve the performance of the solid oxide fuel cell and the electrolytic cell by a simple preliminary heat treatment without any heat treatment. A solid oxide fuel cell having a stable fuel (hydrogen) electrode, and an electrolytic cell and a method of manufacturing the same.

In order to achieve the above object, the present invention provides a process for the production of a semiconductor material comprising the steps of: (a) preparing a compound represented by the following general formula (1): wherein R 1 is selected from the group consisting of Gd (gadolinium) oxide, Gd-doped ceria, Gd salt, Sm (samarium) oxide, Sm-doped ceria, Sm salt, A fuel (hydrogen) electrode layer impregnated with an impregnation solution containing at least one impregnation component; An electrolyte layer formed on the fuel (hydrogen) electrode layer; And an air (oxygen) electrode layer formed on the electrolyte layer, and an electrolytic cell.

In the present invention, the fuel (hydrogen) electrode layer includes nickel and zirconia, preferably Ni-YSZ.

In the present invention, the electrolyte layer may include at least one selected from the group consisting of zirconia, ceria, bismuth oxide, and LaSrGaMg oxide.

The zirconia used in each of the fuel (hydrogen) electrode layer and the electrolyte layer in the present invention is zirconia stabilized with yttria, scandia, magnesia or calcium oxide, preferably yttria stabilized zirconia (YSZ).

In the present invention, the concentration of the impregnation component impregnated on the surface of the fuel (hydrogen) electrode layer is preferably 1 to 50 mg / cm 2.

In the present invention, the impregnation solution may be in the form of a suspension, a solution or a melt containing the impregnation component, and the salt used as the impregnation component may be nitrate, sulfate, chloride or hydrated salt.

The present invention also provides a method of manufacturing a fuel cell, comprising: forming a fuel (hydrogen) electrode layer; Forming an electrolyte layer on the fuel (hydrogen) electrode layer; Wherein the impregnation liquid contains at least one impregnation component selected from the group consisting of Gd oxide, Gd-doped ceria, Gd salt, Sm oxide, Sm-doped ceria, Sm salt, ceria, ; And forming an air (oxygen) electrode layer on the electrolyte layer. The present invention also provides a method of manufacturing an electrolytic cell.

According to an embodiment of the present invention, the impregnation component may be subjected to a heat treatment at a temperature of 200 to 1400 캜 at least once (calcining step), followed by a reduction treatment at an initial stage of operation. When operating in the electrolysis or fuel cell mode in the operating temperature range of 400 ° C to 950 ° C, reduction pretreatment is carried out with hydrogen or hydrocarbon fuel gas. The NiO-YSZ used for the initial fuel (hydrogen) electrode in the reduction pretreatment is formed of a material that acts as an electrode while being reduced to Ni (nickel) metal and converted into a composite of Ni-YSZ.

According to another embodiment of the present invention, the impregnation component can be simultaneously sintered in a normal operation without a pre-heat treatment, so that the heat treatment and the reduction treatment can be simultaneously performed at the initial stage of operation. In this case, the direct reduction pretreatment (400 ° C. to 950 ° C.) instead of the above-mentioned heat treatment in the range of 200 to 1400 ° C. replaces the calcination step and serves as the impregnated electrode.

In the production process of the present invention, a certain amount of impregnation component can be repeatedly impregnated until impregnation.

The present invention is characterized by impregnating a suspension of Gd ₂ O ₃ or Sm ₂ O ₃ ceramic powder (or a suspension of GDC or SDC powder) to a Ni-YSZ fuel (hydrogen) electrode, (Or hydrogen) pole in a solution (or melting and dissolving) the solution to a fuel (hydrogen) solution and then simultaneously sintering the unit cell in a process of heating the unit cell beforehand or heating it to a normal operating temperature without heat treatment. A solid oxide fuel cell, an electrolytic cell and a method of manufacturing the same are provided. Thus, the manufacturing time and process of the solid oxide fuel cell and the electrolytic cell can be shortened, and the cost for manufacturing the cell can be reduced. In addition, YSZ-based electrolytes and fuel (hydrogen) electrodes are able to overcome the performance degradation of ceria-based electrolytes and fuel (hydrogen) electrodes at the same time while overcoming the weakness of mechanical strength. Therefore, the Ni-YSZ fuel (hydrogen) electrode layer impregnated with Gd ₂ O ₃ or Sm ₂ O ₃ (or GDC, SDC, Gd salt or Sm salt) exhibits stable high performance in SOEC and SOFC modes in water vapor electrolysis and has high durability .

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a view showing a configuration of a single cell of a fuel (hydrogen) electrode support type solid oxide fuel cell and an electrolytic cell impregnated with a Gd or Sm component according to an embodiment of the present invention. FIG.
FIG. 2 shows electron micrographs (SEM) of microstructure of Ni-YSZ fuel (hydrogen) electrode before co-sintering according to Gd impregnation amount (0, 5.2, 10.4, 20.4 mg /
3 is _{800 ℃, H 2 O / H} 2 = Gd -impregnated Ni-YSZ electrode, Ni-YSZ electrode, with respect to the Ni-GDC electrode SOFC / graph showing the current / voltage change in SOEC mode in an atmosphere of 70/30 to be.
4 shows the change of current / voltage performance according to the operating temperature change (700 ° C., 750 ° C., 800 ° C.) of Gd-impregnated Ni-YSZ / YSZ / LSM-YSZ cells in an atmosphere of H ₂ O / H ₂ = 70 / FIG.
FIG. 5 is a graph showing current / voltage performance according to changes in the amount of water vapor (H ₂ O / H ₂ = 50/50, 70/30, 90/10) of Gd-impregnated Ni-YSZ / YSZ / LSM-YSZ cells at 800 ° C. FIG.
FIG. 6 is a graph showing the relationship between the Ni-YSZ / YSZ / LSM-YSZ cell (A) and the Gd (YSZ) cell for 200 hours under a steam condition of 800 ° C., 0.1 A / cm 2 and H ₂ O / H ₂ = 70 / YSZ / LSM-YSZ cell (B) of the impregnated Ni-YSZ / YSZ / LSM-YSZ cell.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

1, the fuel (hydrogen) electrode support type solid oxide fuel cell and the electrolytic cell according to the present invention sequentially form a fuel (hydrogen) electrode layer 100, an electrolyte layer 110, and air (oxygen) And an electrode layer (120).

The fuel (hydrogen) electrode layer 100 is made of a mixture of a metal component and an electrolyte component. Nickel, cobalt, and platinum can be used as the metal component. Examples of the electrolyte component include zirconia, ceria, bismuth oxide, LaSrGaMg oxide, Preferably a zirconia-based electrode containing nickel and zirconia, more preferably Ni-YSZ.

The fuel (hydrogen) electrode layer 100 is formed of a material selected from the group consisting of Gd oxide (Gd ₂ O ₃ ), Gd-doped ceria (GDC), Gd salt, Sm oxide (Sm ₂ O ₃ ), Sm- , Ceria, and ceria. The impregnation solution is impregnated with impregnation solution containing at least one impregnation component.

As the impregnation method, an addition method using a syringe, spin coating, spray coating, dipping, or the like can be used. As the salt, nitrates, sulfates, chlorides, hydrates and the like can be used. The impregnation component may be one of the above-mentioned components or may be used in combination of two or more. For example, in the case of Gd salt or Sm salt, it may be used simultaneously with ceria or ceria.

The impregnation solution may be in the form of a suspension, solution or melt containing the impregnation component. In the case of Gd ₂ O ₃ , GDC, Sm ₂ O ₃ and SDC, the impregnation solution is used in the form of a slurry containing ceramic powder, Gd salt and Sm salt can be used in the form of a solution in which these salts are dissolved or in the form of a melt in which a salt is melted. And in the case of solution form, it has an advantageous effect in terms of production of impregnation solution and the like. In addition, the impregnating liquid may contain organic substances, organic solvents, etc. in order to control viscosity, adhesiveness and dispersibility.

For example, the suspension of Gd ₂ O ₃ , GDC, Sm ₂ O ₃ , and SDC has a concentration of 0.1 to 2 M and contains 5 to 35 wt% of ceramic powder (Gd ₂ O ₃ , GDC, Sm ₂ O ₃ , SDC) , 60 to 90 wt% of a solvent (water, alcohol, xylene, etc.), and 1 to 10 wt% of organic materials (polyvinyl pyrrolidone, polyethylene glycol, butvar and the like).

The concentration of the impregnation component impregnated on the surface of the hydrogen electrode layer 100 is preferably 1 to 50 mg / cm 2, more preferably 2 to 20 mg / cm 2 to obtain homogeneous characteristics by simultaneous sintering and to obtain high performance. Lt; 2 >

The electrolyte layer 110 is made of an electrolyte material and is composed of zirconia (CaO, MgO, Sc ₂ O ₃ , Y ₂ O ₃ doped ZrO ₂ ), ceria (Sm ₂ O ₃ , Gd ₂ O ₃ , Y ₂ O ₃ doped CeO ₂ ), perovskite oxides ((La, Sr) (Ga, Mg) O _{3 -δ} , Ba (Ce, Gd) O _{3 -δ} and bismuth oxide Zirconia (ZrO ₂ ) may be stabilized with yttria (Y ₂ O ₃ ), scandia (Sc ₂ O ₃ ), magnesia (MgO) or calcium oxide (CaO) It is preferable that the electrolyte layer 110 is made of yttria stabilized zirconia (YSZ).

The air (oxygen) electrode layer 120 is an electrode in which reduction of oxygen and oxidation of oxygen ions occur. As the electrode material, a mixed oxide of a perovskite structure of ABO ₃ type having electron conduction property Typical cathode materials include lanthanum-strontium manganate (LSM), lanthanum-strontium cobaltite (LSC), lanthanum-strontium ferrite (LSF) , And lanthanum-strontium-cobalt-iron oxide (LSCF, lanthanum strontium cobaltite ferrite). As the oxygen electrode material preferred in the present invention, lanthanum-strontium-manganese oxide (LSM) or lanthanum-strontium-cobalt-iron oxide (LSCF) may be used.

The method of manufacturing a solid oxide fuel cell and an electrolytic cell according to the present invention includes the steps of: (1) forming a fuel (hydrogen) electrode made of NiO (or Ni) -YSZ; (2) forming an electrolyte layer made of YSZ or the like on the fuel (hydrogen) electrode; (3) making an impregnation solution containing Gd ₂ O ₃ , Sm ₂ O ₃ , GDC, SDC, Gd salt and / or Sm salt, and the like; (4) impregnating a fuel (hydrogen) electrode with an impregnation solution; (5) coating a slurry containing an oxygen electrode material on the electrolyte layer to form an oxygen electrode through heat treatment; Subsequently, a subsequent heat treatment or an in-situ sintering step is performed.

In the present invention, simultaneous sintering refers to a process of sintering a solid oxide fuel cell and an electrolytic cell by sintering the impregnation components Gd ₂ O ₃ , Sm ₂ O ₃ , GDC, SDC, Gd and / Means that the fuel (hydrogen) electrode impregnated with the impregnation component is sintered (heat-treated) during heating or normal operation to a normal operating temperature for the operation of the solid oxide fuel cell and the electrolytic cell without performing the heat treatment.

In the case of the solid oxide fuel cell and the electrolytic cell according to the present invention, the temperature during normal operation is around 800 ° C. (Hydrogen) electrode impregnated with an impregnation component at the first elevated temperature for operation of the fuel cell and the electrolytic cell is sintered, and the fuel (hydrogen) electrode layer is sintered by repeated operation of on / Can be added. Preferably, the rate of temperature rise to the operating temperature is 2.5 to 3.5 DEG C / min.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings in order to facilitate a person skilled in the art to which the present invention belongs.

[Example 1]

This embodiment is a case where a suspension (slurry) of Gd ₂ O ₃ (or Sm ₂ O ₃ ) ceramic powder is used as an impregnation solution.

(1) NiO powder and 8 mol% YSZ are mixed mechanically at a ratio of 60:40 or 50:50 for fuel (hydrogen) electrode production. Also, 12 wt% starch is mixed together with the pore forming agent to form sufficient porosity. A wet ball mill is performed using ethanol for 24 hours and dried in an oven at 70 DEG C for 24 hours. The obtained powder is formed through uniaxial pressing (1 metric ton, 30s) and sintered at 1200 ° C for 2 hours. The pellets are 25.5-26.5 mm in diameter and 1.15-1.25 mm in thickness.

(2) YSZ electrolyte layer A slurry is prepared for dip coating and mixed with 15wt% binder, 2wt% dispersant, 10wt% plasticizer and YSZ powder. A wet ball mill is applied for 36 hours to form a YSZ electrolyte layer by dip coating. The formed reversed zirconia (NiO-YSZ / YSZ) sintered at 1500 ℃ for 4 hours, and the formed electrolyte layer has a thickness of 22-28 ㎛.

(3) A mixture of 20 wt% Gd ₂ O ₃ or Sm ₂ O ₃ powder, 78 wt% organic solvent (mixture of butanol and xylene), 1 wt% polyvinyl pyrrolidone, 0.5 wt% polyethylene glycol and 0.5 to prepare an impregnated Gd ₂ O ₃ slurry solution containing wt% butvar.

(4) When the air electrode is excluded for immersion and the sintered body of the electrolyte and the fuel (hydrogen) electrode is immersed in the impregnation suspension (slurry) and the entire vessel is evacuated by vacuum, air is discharged from the pores in the fuel It happens. The amount of Gd ₂ O ₃ impregnated in the NiO (or Ni) -YYSZ fuel (hydrogen) electrode to obtain homogeneous characteristics and obtain high performance is repeated once or more times with 1 to 100 mg / cm 2. Impregnated and dried at 70 ° C.

(5) Lastly, LSM (or LSCF) -YSZ ink is prepared by using α-terpineol (Sigma Aldrich, USA) and cellulose using commercial powder for air electrode production (attachment). LSM (or LSCF) and YSZ mixed electrode were prepared at 50:50 wt% and were formed by screen printing on YSZ electrolyte using the prepared ink. Thereafter, the electrode is sintered at 1100 ° C for 2 hours to form an electrode having an effective area of 0.785 cm 2 and a thickness of 25-30 탆.

[Example 2]

This embodiment is a case where a suspension (slurry) of a Gd-doped ceria (GDC) (or Sm-doped ceria (SDC)) ceramic powder is used as an impregnation solution.

(1) NiO powder and 8 mol% YSZ are mixed mechanically at a ratio of 60:40 or 50:50 for fuel (hydrogen) electrode production. Also, 12 wt% starch is mixed together with the pore forming agent to form sufficient porosity. A wet ball mill is performed using ethanol for 24 hours and dried in an oven at 70 DEG C for 24 hours. The obtained powder is formed through uniaxial pressing (1 metric ton, 30s) and sintered at 1200 ° C for 2 hours. The pellets are 25.5-26.5 mm in diameter and 1.15-1.25 mm in thickness.

(2) YSZ electrolyte layer A slurry is prepared for dip coating and mixed with 15wt% binder, 2wt% dispersant, 10wt% plasticizer and YSZ powder. A wet ball mill is applied for 36 hours to form a YSZ electrolyte layer by dip coating. The formed reversed zirconia (NiO-YSZ / YSZ) sintered at 1500 ℃ for 4 hours, and the formed electrolyte layer has a thickness of 22-28 ㎛.

(3) A powder mixture of 20 wt% Gd-doped ceria (GDC) (or Sm-doped ceria (SDC)) ceramic powder, 78 wt% organic solvent (mixture of butanol and xylene) (GDC) (or Sm-doped ceria (SDC)) ceramic powder suspension (slurry) solution containing 0.5 wt% polyethylene glycol and 0.5 wt% butvar.

(4) If the air electrode is excluded for immersion and the sintered body of electrolyte and fuel (hydrogen) electrode is immersed in the slurry for impregnation, and the entire vessel is evacuated by vacuum, the air is discharged from the pores in the fuel (hydrogen) The amount of Gd-doped ceria (GDC) (or Sm-doped ceria (SDC)) ceramic powders impregnated in a Ni-YSZ fuel (hydrogen) electrode for obtaining homogeneous characteristics and high performance is 1 to 100 mg / Repeat the impregnation with as many times or as many times. Impregnated and dried at 70 ° C.

(5) Lastly, LSM (or LSCF) -YSZ ink is prepared by using α-terpineol (Sigma Aldrich, USA) and cellulose using commercial powder for air electrode production (attachment). LSM (or LSCF) and YSZ mixed electrode were prepared at 50:50 wt% and were formed by screen printing on YSZ electrolyte using the prepared ink. Thereafter, the electrode is sintered at 1100 ° C for 2 hours to form an electrode having an effective area of 0.785 cm 2 and a thickness of 25-30 탆.

[Example 3]

This embodiment is a case where a (water) solution of Gd salt (nitric acid) (or Sm salt (nitric acid)) is used as an impregnation solution.

(1) NiO powder and 8 mol% YSZ are mixed mechanically at a ratio of 60:40 or 50:50 for fuel (hydrogen) electrode production. Also, 12 wt% starch is mixed together with the pore forming agent to form sufficient porosity. A wet ball mill is performed using ethanol for 24 hours and dried in an oven at 70 DEG C for 24 hours. The obtained powder is formed through uniaxial pressing (1 metric ton, 30s) and sintered at 1200 ° C for 2 hours. The pellets are 25.5-26.5 mm in diameter and 1.15-1.25 mm in thickness.

(2) YSZ electrolyte layer A slurry is prepared for dip coating and mixed with 15wt% binder, 2wt% dispersant, 10wt% plasticizer and YSZ powder. A wet ball mill is applied for 36 hours to form a YSZ electrolyte layer by dip coating. The formed reversed zirconia (NiO-YSZ / YSZ) sintered at 1500 ℃ for 4 hours, and the formed electrolyte layer has a thickness of 22-28 ㎛.

(3) The Gd salt (nitric acid) (or Sm salt) (water) solution may contain organic substances and organic solvents for controlling viscosity, adhesiveness and dispersibility. Alternatively, a molten salt of a Gd salt (nitric acid) (or Sm salt) may be prepared and impregnated with the same to obtain the same effect. Preferably, the solution has a concentration of 0.2 M and contains water or alcohols as a solvent. It is preferable that the amount of nitrate impregnated in the NiO (or Ni) -YYSZ fuel (hydrogen) electrode is 1 to 50 mg / cm 2 for achieving homogeneous characteristics by simultaneous sintering.

(4) If the air electrode is excluded for immersion and the sintered body of electrolyte and fuel (hydrogen) electrode is immersed in a solution of Gd (or Sm) water for impregnation and the entire vessel is evacuated, air is discharged from pores in the fuel The impregnation of the solution in which the salt is dissolved occurs uniformly. The amount of Gd salt (nitric acid) impregnated in the NiO (or Ni) -YYSZ fuel (hydrogen) electrode for obtaining homogeneous characteristics and high performance is 1 to 100 mg / cm 2, and the impregnation is repeated once or more times do. Impregnated and dried at 70 ° C.

(5) Lastly, LSM (or LSCF) -YSZ ink is prepared by using α-terpineol (Sigma Aldrich, USA) and cellulose using commercial powders for air electrode fabrication (attachment). LSM (or LSCF) and YSZ mixed electrode were prepared at 50:50 wt%, and were formed by screen printing on YSZ electrolyte using the prepared ink. Thereafter, the electrode is sintered at 1100 ° C for 2 hours to form an electrode having an effective area of 0.785 cm 2 and a thickness of 25-30 탆.

[Test Example]

Fig. 2 is a graph showing the relationship between the Gd ₂ O ₃ (Or Sm ₂ O ₃₎ impregnated amount (a) 0, (b) 5.2, (c) 10.4, (d) prior to co-sintering of the Ni-YSZ electrode of the 20.4 mg / ㎠ a microstructure SEM analysis. When the impregnation amount of Gd ₂ O ₃ (or Sm ₂ O ₃ ) is 10.4 mg / cm 2, it has an appropriate microstructure as an electrode.

Figure 3 is _{H 2 O / H 2 = 70/30} (54% H 2 O + 23% H 2 + 23% N 2) atmosphere, a fuel cell (SOFC) under operating conditions of 800 ℃ of the electrolysis (SOEC) mode (Hydrogen) electrode of the fuel cell. The three electrode measurement method was used to compare the performance of the fuel (hydrogen) electrode in the SOFC and SOEC modes. The measurement results were analyzed using a Tafel plot. Gd ₂ O ₃ (Or Sm ₂ O ₃₎ The overvoltage according to the current density of the impregnated fuel (hydrogen) electrode was measured and compared with Ni-YSZ (NiO before reductive pretreatment, hereinafter referred to as Ni only) electrode and Ni-GDC electrode. The activity of the Ni-YSZ electrode was different in SOFC mode and SOEC mode, and the activity for hydrogen oxidation was higher than the activity for water vapor electrolysis reaction. In contrast, Ni-GDC electrodes exhibited similar activity in the SOFC and SOEC modes, all with relatively high performance and activity. This suggests that the Ni-GDC electrode is more suitable for the reversible system of SOFC / SOEC. The ability to operate SOFC and SOEC together with high efficiency in the same system will have a major impact on total cost savings.

In FIG. 3, the Ni content in the electrode (Ni-YSZ, Ni-GDC) was all 60 wt%, which indicates the role of the GDC component in the electrolytic bath and the inhibition of oxidation of the Ni surface in a high water vapor atmosphere . Under the above atmosphere, the surface oxidation of Ni forms an inactive layer, which is a reason for the performance reduction of the electrode under electrolysis conditions. However, when the Ni-YSZ electrode is doped with Gd ₂ O ₃ (Or Sm ₂ O ₃ ), SOFC activity was higher than that in SOEC mode, but Gd ₂ O ₃ (Or Sm ₂ O ₃₎ The activity at SOEC was higher than that of Ni-YSZ electrode without impregnation, and showed a relatively symmetrical tendency in SOEC and SOFC modes.

FIG. 4 is a graph showing the relationship between Gd ₂ O ₃ (Or Sm ₂ O ₃ ) impregnated Ni-YSZ / YSZ / LSM-YSZ cell. The H ₂ O / H ₂ ratio was fixed at 70/30 and the operating temperature was changed to 700 ° C, 750 ° C and 800 ° C respectively. As expected, as the operating temperature increases, the performance of SOEC increases, which is similar to the increase in SOFC performance.

FIG. 5 shows changes in cell performance depending on the water vapor content in the SOFC and SOEC modes. The current / voltage curve varied with the H ₂ O / H ₂ ratio, the ratio being H ₂ O / H ₂ = 50/50, 70/30 and 90/10, and the temperature was fixed at 800 ° C. The higher the water vapor content, the lower the OCV, which is consistent with the Nernst potential. Gd ₂ O ₃ (Or Sm ₂ O ₃ ) impregnated Ni-YSZ cell, the performance was changed in the SOFC mode as the water vapor content was changed. In contrast, in the SOEC mode, a similar performance was measured regardless of the change in the water vapor content. The overvoltage was slightly increased when the H ₂ O / H ₂ ratio was increased from 50/50 to 70/30, and the overvoltage was significantly increased when the ratio was increased from 50/50 to 90/10. This is considered to be due to the sensitivity of GDC conductivity depending on the oxygen partial pressure, which can be a disadvantage in using GDC as an electrode material. However, a trace amount of Gd ₂ O ₃ (Or Sm ₂ O ₃ ) impregnation method was used.

6 is a graph showing the relationship between the concentration of Gd ₂ O ₃ at 800 ° C and the current density of 0.1 A cm ₂ , H ₂ O / H ₂ ratio of 70/30 (Or Sm ₂ O ₃₎ is the result of the durability test for 200 hours of the impregnated Ni-YSZ / YSZ / LSM- YSZ cells with Ni-YSZ / YSZ / LSM- YSZ cell mainly used in conventional. As a result, Gd ₂ O ₃ (Or Sm ₂ O ₃ ), the durability of the performance is significantly improved, and it is easy to impregnate Gd ₂ O ₃ (or Sm ₂ O ₃ ) into the NiO (Ni) -YYSZ fuel But it is an efficient method of improving performance and durability. The test results for Example 2 (impregnation with GDC or SDC powder suspension) and Example 3 (Gd salt or Sm salt solution or melt impregnation) are the same as described above.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, Those skilled in the art will recognize that many modifications and variations are possible in light of the above teachings.

Accordingly, the spirit of the present invention should not be construed as being limited to the embodiments described, and all of the equivalents or equivalents of the claims, as well as the following claims, belong to the scope of the present invention .

100: fuel (hydrogen) electrode layer
110: electrolyte layer
120: air (oxygen) electrode layer

Claims (11)

Impregnated with an impregnation solution comprising 5 to 35 wt% of Sm ₂ O ₃ as an impregnation component, 60 to 90 wt% of a mixed solution of butanol and xylene as a solvent, and 1 to 10 wt% of organic materials containing polyvinylpyrrolidone and polyethylene glycol A fuel (hydrogen) electrode layer;
An electrolyte layer formed on the fuel (hydrogen) electrode layer; And
(Oxygen) electrode layer formed on the electrolyte layer by using lanthanum-strontium-manganese oxide or lanthanum-strontium-cobalt-iron oxide, yttria stabilized zirconia,? -Terpineol or cellulose,
The fuel (hydrogen) electrode layer includes nickel and zirconia,
Wherein the electrolyte layer comprises at least one selected from the group consisting of zirconia, ceria, bismuth oxide, and LaSrGaMg oxide,
Zirconia is zirconia stabilized with yttria, scandia, magnesia or calcium oxide,
The concentration of the impregnation component impregnated on the surface of the fuel (hydrogen) electrode layer is 8 to 12 mg / cm 2,
Wherein the impregnating liquid is a suspension containing an impregnating component. delete delete delete delete delete delete A method for producing a solid oxide electrolytic cell according to claim 1,
Forming a fuel (hydrogen) electrode layer;
Forming an electrolyte layer on the fuel (hydrogen) electrode layer;
An impregnation solution comprising 5 to 35 wt% of Sm ₂ O ₃ as an impregnation component, 60 to 90 wt% of a mixed solution of butanol and xylene as a solvent, and 1 to 10 wt% of organic material containing polyvinylpyrrolidone and polyethylene glycol (Hydrogen) electrode layer; And
(Oxygen) electrode layer on the electrolyte layer using lanthanum-strontium-manganese oxide or lanthanum-strontium-cobalt-iron oxide, yttria stabilized zirconia,? -Terpineol or cellulose,
The impregnation component is subjected to a heat treatment at a temperature in the range of 200 to 1400 ° C at least once and then subjected to a reduction treatment at the initial stage of the operation or to the simultaneous sintering of the impregnated component under normal operation without preheating, Processing simultaneously,
The concentration of the impregnation component impregnated on the surface of the fuel (hydrogen) electrode layer is 8 to 12 mg / cm 2,
And then impregnating the solid oxide electrolytic cell repeatedly until a predetermined amount of the impregnation component is impregnated. delete delete delete

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