KR20170076143A - Cell for solid oxid fuel cell comprising reaction preventing layer and method for manufacturing the same - Google Patents

Abstract

According to an embodiment of the present invention, there is provided a cell for a solid oxide fuel cell comprising a fuel electrode layer, an electrolyte layer and a cathode layer, wherein the first reaction preventive layer is formed on the electrolyte layer and comprises 0.5 to 3 mol% And a second reaction preventive layer formed on the first reaction preventive layer and including 10 to 35 mole percent of a sintering auxiliary agent so as to densify the structure of the reaction preventive layer It is possible to effectively prevent the direct contact between the cathode layer and the electrolyte layer to ensure long-term stability of the cell, to improve the performance by reducing the internal resistance of the cell, and to reduce the manufacturing cost by manufacturing a cell for a solid oxide fuel cell with a simple process .

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a cell for a solid oxide fuel cell including a reaction preventive layer,

The present invention relates to a cell for a solid oxide fuel cell including an anti-reaction layer and a method of manufacturing the same.

Since the fuel cell generates electric power through the electrochemical reaction of hydrogen and oxygen, it is not subject to the carnot cycle like the thermal power generation depending on the existing internal combustion engine, has a high power generation efficiency, has low noise, Environmental impacts are very low. The operating temperature of a fuel cell is determined according to the electrolyte to be used. The fuel cell is classified into a polymer electrolyte fuel cell, a solid oxide fuel cell, a molten carbonate fuel cell, and a direct methanol fuel cell.

Solid oxide fuel cells (SOFCs) have the highest efficiency, and when combined with high heat, cogeneration is a very ideal system with power generation efficiencies approaching 70-80%. The solid oxide fuel cell is composed of an electrolyte having oxygen ion conductivity and a fuel electrode and an air electrode provided on both sides thereof. In this case, oxygen and fuel are supplied to the air electrode and the fuel electrode, respectively, so that a reduction reaction of oxygen occurs in the air electrode, and oxygen ions are generated and transferred to the fuel electrode through the electrolyte. In the fuel electrode, . The electrolyte and the electrode which are the basic constituent elements of the solid oxide fuel cell having the above-mentioned principle are all made of ceramics having excellent heat resistance and have excellent efficiency and performance as compared with the low temperature type fuel cell because they operate at high temperature.

However, the solid oxide fuel cell must be exposed to a high temperature for a long time during cell manufacturing and operation, and various deterioration phenomena occur in this process, so that it is difficult to commercialize the solid oxide fuel cell. More specifically, a large resistance material such as La ₂ Zr ₂ O ₇ or SrZrO ₃ is formed at the interface between the air electrode and the electrolyte to increase the resistance and to decrease the performance of the cell. Also, the thermal expansion coefficient difference between the air electrode / There arises a problem that the thermomechanical stability is lowered.

Accordingly, techniques for preventing the reaction between the air electrode and the electrolyte have been developed in order to solve the above-mentioned problems and improve the performance and stability of the solid oxide fuel cell. Among them, a ceria-based reaction preventive layer provided between the cathode and the electrolyte is known, but a ceria-based material is a typical ozone-forming substance and it is difficult to make a dense sintering. In the state where the electrolyte layer is already sintered densely, It is very difficult to form a dense layer by applying ceria-based materials. Further, in order to form a ceria-based reaction preventive layer, the sintering process should be carried out at a high temperature exceeding 1300 DEG C, but at such a high temperature, a second phase is formed to cause electric conductivity, thereby rapidly deteriorating the cell performance.

Conventionally, expensive deposition methods requiring high vacuum such as sputtering and pulsed laser deposition have been used to form a dense film, but this is not appropriate in terms of mass productivity and cost reduction. In addition, in order to form a dense film, a sintering auxiliary agent was added to the reaction preventing side. However, when 0.5 to 3 mole percent of the sintering auxiliary agent was added, it was not enough to make the reaction preventing layer compact. Sintering ability is low even when the amount is more than 10 mol%, and the sintering aid having a mole ratio of 10 mol% or more has a disadvantage that it affects the conductivity because it is similar to the content of dopant added to increase the ion conductivity of ceria.

An object of the present invention is to provide a cell for a solid oxide fuel cell having an anti-reaction layer having a dense structure between a cathode layer and an electrolyte layer and having excellent electric production and electrolysis performance and ensuring long-term stability.

The present invention also provides a method of manufacturing a cell for a solid oxide fuel cell including an anti-reaction layer by a simple process.

According to an embodiment of the present invention, there is provided a cell for a solid oxide fuel cell comprising a fuel electrode layer, an electrolyte layer and a cathode layer, wherein the first reaction preventive layer is formed on the electrolyte layer and comprises 0.5 to 3 mol% And the second reaction preventive layer formed on the first reaction preventive layer and including 10 to 35 mole percent of a sintering auxiliary agent.

The electrolyte layer may be at least one selected from the group consisting of yttria stabilized zirconia (YSZ), scandia stabilized zirconia (ScSZ), samarium doped ceria (SDC), gadolinia doped ceria (GDC) and lanthanum gallate.

The cathode layer has a perovskite structure and is composed of lanthanum (La), cobalt (Co), strontium (Sr), calcium (Ca), gadolinium (Gd), barium (Ba), magnesium (Mg) (Ti), Cr, Mn, Ni, Fe, Cu, and Zr.

The first reaction preventing layer and the second reaction preventing layer may include a ceria based metal oxide.

The rare earth metal may be added to the ceria based metal oxide.

The sintering aid may be at least one selected from the group consisting of copper, copper oxide, cobalt, cobalt oxide, calcium, calcium oxide, zirconium, zirconium oxide, iron, iron oxide, lithium and lithium oxide.

According to another embodiment of the present invention, there is provided a method for manufacturing a fuel cell, comprising the steps of: forming a fuel electrode layer and an electrolyte layer of a solid oxide on the fuel electrode layer; forming a composition for a first reaction inhibition layer containing 0.5 to 3 mole percent of a sintering auxiliary agent on the electrolyte layer Coating a first reaction inhibiting layer on the first reaction inhibiting layer to form a second reaction inhibiting layer by coating a composition for a second reaction inhibiting layer containing 10 to 35 mole percent of a sintering auxiliary agent on the first reaction preventing layer A method for manufacturing a cell for a solid oxide fuel cell is provided.

And sintering the first reaction preventing layer and the second reaction preventing layer.

Forming a cathode layer by coating the composition for a cathode layer on the second reaction inhibition layer, and sintering the first reaction inhibition layer, the second reaction inhibition layer and the air electrode layer.

The coating can be made continuously by a screen printing process.

The sintering temperature may be 800 to 1300 占 폚.

According to the present invention, the structure of the reaction preventive film is densified to effectively prevent the direct contact between the cathode layer and the electrolyte layer, thereby securing the long-term stability of the cell, improving the performance by reducing the internal resistance of the cell, There is an effect that the manufacturing cost of the battery cell can be reduced.

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a schematic view showing a cross section of a cell for a solid oxide fuel cell according to the present invention. FIG.
2 is a scanning electron microscope (SEM) photograph of a cross-section of a cell prepared from an example.
3 is a scanning electron microscope (SEM) photograph of a cross section of a cell prepared from Comparative Example.

Hereinafter, preferred embodiments of the present invention will be described with reference to various embodiments. However, the embodiments of the present invention can be modified into various other forms, and the scope of the present invention is not limited to the embodiments described below.

The present invention relates to a cell for a solid oxide fuel cell including an anti-reaction layer and a method of manufacturing the same.

The reaction preventive layer means a layer interposed therebetween to prevent or suppress a chemical reaction between the cathode layer and the electrolyte layer of the solid oxide fuel cell. At this time, the reaction preventive layer should be able to prevent the internal resistance from being increased by diffusion of elements of the air electrode layer to form a reactant with the electrolyte layer. If the pores of the reaction preventive layer are large, And thus it is necessary to have a dense structure. In order to have such a dense structure, sintering should be performed at a temperature exceeding 1300 ° C. However, if sintering is performed at such a high temperature, a non-reactant reaction product is generated between the electrolyte layer and the reaction preventive layer to degrade the performance of the fuel cell. It is important to prepare an anti-reaction layer having a dense structure.

Thus, according to one embodiment of the present invention, there is provided a cell for a solid oxide fuel cell comprising a fuel electrode layer, an electrolyte layer and a cathode layer, wherein the first electrode comprises a first sintering auxiliary agent which is formed on the electrolyte layer and contains 0.5 to 3 mol% And a second reaction preventive layer formed on the first reaction preventive layer and including 10 to 35 mole percent of a sintering auxiliary agent.

1 is a schematic view showing a cross section of a cell for a solid oxide fuel cell according to the present invention. According to this, a cell for a solid oxide fuel cell comprises an anode layer 1, an electrolyte layer 2 and a cathode layer 3 And the first and second reaction preventing layers 3 and 4 are provided between the cathode layer and the electrolyte layer.

Since the fuel electrode layer 1 serves as an electrochemical reaction and charge transfer of the fuel, the fuel electrode catalyst is chemically stable and has a similar thermal expansion coefficient to the material forming the electrolyte layer 2, . The material of the anode layer may be a zirconia-based metal oxide including a pure metal catalyst such as Ni, Co, Ru, and Pt, such as a Ni / YSZ composite (ceramic-metallic composite) and Ru / YSZ summit. It is preferable that the fuel electrode layer has porosity so that the fuel gas can be diffused well. In addition, the fuel electrode layer and the electrolyte layer may include an anode function layer in order to promote the electrochemical reaction of the fuel.

The electrolyte layer 2 should be dense so that air and fuel are not mixed with each other, have high oxygen ion conductivity and low electron conductivity. In addition, since the electrolyte layer has a very large oxygen partial pressure difference on both sides, it is necessary to maintain the above properties in a wide range of oxygen partial pressure. Such an electrolyte layer is characterized by being a zirconia-based metal oxide generally used in the related art. More preferably, it may be at least one selected from the group consisting of yttria stabilized zirconia (YSZ), scandia stabilized zirconia (ScSZ), samaria-doped ceria (SDC), gadolinia doped ceria (GDC) and lanthanum gallate.

The first and second reaction preventing layers 3 and 4 may be ceria based metal oxides commonly used in the art. More preferably, the rare earth metals include lanthanum (La), yttrium (Y), scandium (Sc), praseodymium (Pr), neodymium (Nd), samarium (Sm) , And gadolinium (Gd).

In addition, the first reaction preventive layer 3 preferably contains 0.5 to 3 mole percent of a sintering auxiliary agent. If the content of the sintering aid is less than 0.5 mole percent, a liquid phase of the ceria-based metal oxide and the sintering auxiliary agent is not formed and the reaction preventing layer is not densified. When the amount exceeds 3 mole percent, a large amount of ceria is uniformly coated it's difficult.

On the other hand, the second reaction preventive layer 4 preferably contains 10 to 35 mole percent of a sintering auxiliary agent. If the sintering aid is contained in an amount less than 10 mol%, the liquid phase between the ceria-based metal oxide and the sintering auxiliary agent is not formed and the reaction preventive layer is not densified. Therefore, the chemical reaction between the cathode layer and the electrolyte layer 2 can not be suppressed, If it is contained in an amount exceeding 35 mole percent, a large amount of a liquid phase of the ceria-based metal oxide and the sintering additive is formed to form a reaction layer with the electrolyte layer, thereby deteriorating the performance of the fuel cell.

The first and second reaction preventing layers 3 and 4 are dense in structure and have excellent ion conductivity as compared with the conventional reaction preventing layer and are disposed between the electrolyte layer 2 and the air electrode layer 5 to effectively prevent element diffusion therebetween To inhibit the formation of the insect reactant. Also, since the first and second reaction preventing layers 3 and 4 can be manufactured by sintering at 800 to 1300 ° C, a second phase is formed during sintering to reduce the electric conductivity, can do.

The sintering auxiliary agent is not particularly limited as long as it is a sintering auxiliary agent capable of densely forming the reaction preventing layers 3 and 4 on the electrolyte layer 2. The sintering auxiliary agent may be copper, Zirconium oxide, iron, iron oxide, lithium, and lithium oxide.

It is preferable that the air electrode layer 5 has porosity so that oxygen gas can be diffused therein. The material of the cathode layer 5 is not particularly limited as long as it can be generally used in the related art. For example, a metal oxide having a perovskite structure can be used. The metal oxide having the perovskite structure is a mixed conductor material having ionic conductivity and electron conductivity at the same time and has a high oxygen diffusion coefficient and a charge exchange rate coefficient so that the electrochemical reaction is performed not only at the three- The electrode activity at low temperature is excellent and can contribute to lowering the operating temperature of the solid oxide cell.

Specifically, the air electrode layer 5 has a perovskite structure and is made of at least one of lanthanum (La), cobalt (Co), strontium (Sr), calcium (Ca), gadolinium (Gd), barium (Mg), a metal selected from titanium (Ti), chromium (Cr), manganese (Mn), nickel (Ni), iron (Fe), copper (Cu) and zirconium desirable.

According to another embodiment of the present invention, a method of manufacturing a cell for a solid oxide fuel cell can be provided.

Specifically, a method for manufacturing a cell for a solid oxide fuel cell according to an embodiment of the present invention includes the steps of forming an anode layer 1 and an electrolyte layer 2 of solid oxide on the anode layer, To 3 mole percent of a sintering auxiliary agent to form a first reaction inhibiting layer (3), and a step of forming a first reaction inhibiting layer (3) on the first reaction inhibiting layer by adding 10 to 35 mole percent of a sintering auxiliary agent And coating the second composition for a reaction prevention layer to form a second reaction prevention layer 4. [

First, a fuel electrode layer 1 and an electrolyte layer 2 of solid oxide on the anode layer can be formed. Coating the electrolyte layer on the anode layer using a thin film process, and drying the electrolyte layer. More preferably, it may be screen printing. At this time, in order to control the amount of paste on the anode support and ensure uniformity, drying conditions may be controlled to dry. The anode layer may be coated with the anode layer before the electrolyte layer is coated on the anode layer support. The step of coating the anode functional layer is the same as the step of coating the electrolyte layer. Thereafter, the fuel electrode functional layer or the electrolyte layer may be sintered to form a laminate of the fuel electrode, the anode functional layer, and the electrolyte layer.

The first and second reaction preventing layers 3 and 4 are positioned between the air electrode layer 3 and the electrolyte layer 2 so that La or Sr of the air electrode layer reacts with the zirconia metal oxide of the electrolyte layer to form La ₂ Zr ₂ O _7, SrZrO _3, and the like.

The reaction preventive layer made of only the conventional ceria based metal oxide can have a dense structure only when it is sintered at a temperature exceeding 1,300 캜. However, since the reaction preventive layer is in contact with the electrolyte layer, when sintering is performed at a high temperature, a chemical reaction occurs with the electrolyte layer, thereby generating a reactant having a low ionic conductivity. In order to solve the above problem, when the reaction preventive layer is sintered at a temperature of 1300 ° C or less, the sinterability is low to have a porous structure, so that a reaction layer is formed due to internal diffusion through pores between the cathode layer and the electrolyte layer, Lt; / RTI >

Therefore, conventionally, in order to form a dense film, expensive deposition methods requiring high vacuum such as sputtering and pulsed laser deposition have been used, but this is not appropriate in view of mass productivity and cost reduction. In addition, although a method of adding a sintering auxiliary agent to the reaction preventing side to form a dense film was used, when the sintering auxiliary agent of 0.5 to 3 molar percent was added, the reaction preventing layer was insufficient to be dense and the sintering property was decreased even when 10 mol% In addition, it has a disadvantage that it affects the conductivity because it is similar to the dopant concentration to increase the ion conductivity of ceria.

Accordingly, in order to solve such a problem, in the present invention, the reaction preventing layers 3 and 4 are sintered at a temperature lower than the above-mentioned temperature so as to have a dense structure to effectively block the reaction between the air electrode layer and the electrolyte layer 2 .

Specifically, according to the present invention, the first reaction preventing layer 3 can be formed by coating a composition for a first reaction preventing layer containing 0.5 to 3 mol% of a sintering auxiliary agent on the electrolyte layer 2. Thereafter, the second reaction preventive layer 4 may be formed on the first reaction preventive layer by coating a composition for a second reaction preventive layer containing 10 to 35 mole percent of a sintering auxiliary agent.

The method of coating the first and second reaction preventive layers 3 and 4 can be continuously performed by a screen printing process. Therefore, compared with a conventional method using sputtering or the like, There is an effect that can be saved.

The first and second reaction preventing layers 3 and 4 may be successively coated and then sintered by a screen printing process. If the sintering temperature is less than 800 ° C, the reaction preventive layer is not sufficiently sintered to form a porous structure and the interface bonding force is insufficient. If the sintering temperature is higher than 1300 ° C, the electrolyte layer 2 and the chemical Reacted to form a reaction layer containing a non-reactant reactant, thereby deteriorating the performance of the cell.

According to an embodiment of the present invention, the cathode layer may be formed by coating the composition for a cathode layer on the second reaction preventive layer before sintering the first and second reaction prevention layers 3 and 4. Thereafter, the first reaction preventing layer, the second reaction preventing layer and the air electrode layer may be simultaneously sintered.

Preferably, the cathode layer is coated by a screen printing process. Since the first and second reaction inhibiting layers and the cathode layer can be continuously coated and simultaneously sintered by a screen printing process, the process is very simple and economical to be. The cell for a solid oxide fuel cell manufactured by such a process can maintain the same level of performance as a cell using an expensive fixation such as sputtering.

Hereinafter, the present invention will be described more specifically by way of specific examples. The following examples are provided to aid understanding of the present invention, and the scope of the present invention is not limited thereto.

Example

(ZrO ₂ ) 0.9 (Y ₂ O ₃ ) _0.1 was formed on the surface of the electrolyte layer, and a layer of Gd _0.1 Ce _0.9 O (0.001 mol) containing 0.5 mole percent of copper oxide (CuO, sintering auxiliary) ₂ (gadolinia doped ceria) was coated with a composition for a first reaction preventing layer by a screen printing method to form a first reaction preventing layer. Since Gd ₀ containing the first cobalt oxide of 30 mole percent on the reaction preventing layer (Mn ₂ O _3, sintering _{aid). 1} Ce _{0 . 9} O ₂ was coated with a composition for a second reaction preventing layer by a screen printing method to form a second reaction preventing layer. On the second reaction preventive layer, La _{0 . 6} Sr _{0 . 4} Co _{0 . 2} Fe _{0 . 8} O ₃ , Gd _{0 . 1} Ce _{0 . 9} O ₂ and La _{0 . 6} Sr _{0 . 4} CoO ₃ was coated by a screen printing method to form a cathode layer, and then the first and second reaction-preventing layers and the cathode layer were simultaneously sintered at 1000 ° C.

Comparative Example

A cell for a solid oxide fuel cell was prepared in the same manner as in the above example except that the second reaction preventive layer was not included.

FIG. 2 is a scanning electron microscope (SEM) photograph of a cross section of a cell prepared from an embodiment, and FIG. 3 is a scanning electron microscope (SEM) photograph of a cross section of a cell prepared from a comparative example. According to the example, it was confirmed that the surface of the cell on which the first and second reaction preventing layers were deposited was formed more densely, but the comparative example was confirmed to be insufficient due to pores formed in the reaction preventing layer.

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 exemplary embodiments, but, on the contrary, It will be obvious to those of ordinary skill in the art.

1: anode layer
2: electrolyte layer
3: First reaction preventive layer
4: Second reaction preventive layer
5: cathode layer

Claims (11)

1. A cell for a solid oxide fuel cell comprising an anode layer, an electrolyte layer and a cathode layer,
A first reaction preventive layer formed on the electrolyte layer and comprising 0.5 to 3 mole percent of a sintering auxiliary agent; And
And a second reaction preventive layer formed on the first reaction preventive layer and including 10 to 35 mole percent of a sintering auxiliary agent.
The method according to claim 1,
Wherein the electrolyte layer comprises at least one solid oxide fuel selected from the group consisting of yttria stabilized zirconia (YSZ), scandia stabilized zirconia (ScSZ), samaria doped ceria (SDC), gadolinia doped ceria (GDC) and lanthanum gallate Battery cell.
The method according to claim 1,
The cathode layer has a perovskite structure and is composed of lanthanum (La), cobalt (Co), strontium (Sr), calcium (Ca), gadolinium (Gd), barium (Ba), magnesium (Mg) And at least two metals selected from the group consisting of Ti, Cr, Mn, Ni, Fe, Cu and Zr.
The method according to claim 1,
Wherein the first reaction preventing layer and the second reaction preventing layer comprise a ceria based metal oxide.
5. The method of claim 4,
Wherein the ceria-based metal oxide is a rare earth-doped solid oxide fuel cell.
The method according to claim 1,
Wherein the sintering aid is at least one selected from the group consisting of copper, copper oxide, cobalt, cobalt oxide, calcium, calcium oxide, zirconium, zirconium oxide, iron, iron oxide, lithium and lithium oxide.
Forming an anode layer, and an electrolyte layer of solid oxide on the anode layer;
Coating a first anti-reaction layer composition comprising 0.5 to 3 mole percent of a sintering aid on the electrolyte layer to form a first anti-reaction layer; And
And forming a second reaction preventing layer by coating a composition for a second reaction preventing layer containing 10 to 35 mole percent of a sintering auxiliary agent on the first reaction preventing layer.
8. The method of claim 7,
And sintering the first reaction preventive layer and the second reaction preventive layer.
8. The method of claim 7,
Coating a composition for a cathode layer on the second reaction preventive layer to form a cathode layer; And
And sintering the first reaction preventive layer, the second reaction preventive layer, and the air electrode layer.
10. The method according to claim 7 or 9,
Wherein the coating is continuous with a screen printing process.
10. The method according to claim 8 or 9,
Wherein the sintering temperature is 800 to 1300 ° C.

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