KR20210045118A - Solid oxide electrolyte including thin film electrolyte layer of multiple repetitive structures, method for manufacturing the same, solid oxide fuel cell and solid oxide electrolysis cell comprising the same - Google Patents

Abstract

The present invention relates to: a solid oxide electrolyte including a thin film electrolyte layer of a multi-repeating structure, capable of solving problems such as low reproducibility and durability of a thin film electrolyte; a method for manufacturing the same; a single cell including the same; a solid oxide fuel cell including the single cell; and a solid oxide electrolyzer including the single cell. Accordingly, the multi-layered electrolyte has the advantage that the stress at the interface of adjacent electrolyte-layers may be stably distributed due to a difference in thermal expansion coefficient.

Description

Solid oxide electrolyte including thin film electrolyte layer of multiple repetitive structures, method for manufacturing the same, solid oxide fuel cell and solid oxide electrolysis cell comprising the same}

The present invention relates to a solid oxide electrolyte including a multi-repeated thin film electrolyte layer, a method of manufacturing the same, a solid oxide fuel cell including the same, and a solid oxide electrolyzer.

Solid Oxide Fuel Cells (SOFCs) or Solid Oxide Elctrolysis Cells (SOEC) are composed of ceramics with excellent heat resistance, both of which are the basic elements of the cell, including electrolytes and electrodes.

Solid oxide fuel cells (SOFCs) began to be developed later than phosphoric acid fuel cells and molten carbonate fuel cells. The SOFC has the highest energy efficiency among several fuel cell types, and due to its high operating temperature up to 1000 ℃, hydrocarbons such as LPG and LNG can be directly used as fuel without an expensive external reformer, as well as pollutants during operation. It has the advantage that the emission of gas is very small compared to the combustion engine.

Therefore, in recent years, since it is possible to maximize thermal efficiency by grafting high-quality high-temperature waste heat generated during operation of the SOFC to household or cogeneration power generation, it has been in the spotlight as a large power generation system as well as small and medium-sized power generation systems such as field power generation.

Solid Oxide Electrolysis Cells (SOEC) can be used as high-temperature electrolysis devices that produce hydrogen from steam by the reverse reaction process of fuel cells, and in the US, nuclear power is used in conjunction with Very High Temperature Reactor (VHTR). High-temperature electrolysis hydrogen production technology is being developed, and hydrogen production has been demonstrated by developing a stack-scale high-temperature electrolysis hydrogen production system in Korea. These SOFCs or SOECs are formed as a multi-layered structure (stack) of a unit cell (cell) composed of a cathode, an anode, and an electrolyte. Among them, the electrolyte layer of SOFC or SOEC serves to provide a passage through which oxygen moves in an ionic state, and the electrolyte layer has the greatest influence on the productivity and performance of a solid oxide fuel cell or a solid oxide electrolyzer. Recently, a lot of research on SOFC or SOEC including a thin film electrolyte formed in the form of a dense thin film on an electrode with a large surface area has been conducted.

In general, thin-film electrolytes exist in the form of A-B as a buffer layer to prevent the formation of a secondary phase caused by reaction with A, which is a main electrolyte, and a cathode.

Electrolytes A and B are generally used as materials with similar coefficients of thermal expansion in order to prevent peeling or cracking due to thermal expansion in high temperature operation. On the other hand, since electrolytes A and B are different materials, there may be some differences in the coefficient of thermal expansion. In this case, since the thick electrolyte has sufficient mechanical strength, it can sufficiently withstand the internal stress caused by the corresponding thermal expansion, but the thin film electrolyte having a thickness of several micrometers or less has very small thermal expansion due to low mechanical strength and a very large high-aspect ratio. Even the difference in coefficient can be subject to great thermal shock.

1 is a diagram showing an internal stress distribution diagram that a conventional A-B type thin film electrolyte receives.

In the A-B type electrolyte structure, an internal stress at the interface between A-B is formed as shown in FIG. 1 at an operating temperature of 400° C. or higher due to a difference in coefficient of thermal expansion. Accordingly, both of the electrolyte layers are subjected to a force to be convexly bent while an expansion stress is applied from an upper side and a compressive stress is applied from a lower side, which causes structural instability.

That is, in the A-B type electrolyte structure, due to a small difference in coefficient of thermal expansion between A and B, there is a possibility that the stress generated at the A-B interface is bent, cracked, or peeled due to thermal shock, and there is a problem of thermal instability.

Korean Patent Registration No. 10-0692642

The present invention is to solve the above-described problems, a solid oxide electrolyte including a thin film electrolyte layer having a multi-repeating structure capable of solving problems such as low reproducibility and thermal durability of the thin film electrolyte, a method of manufacturing the same, and a unit cell including the same , To provide a solid oxide fuel cell including a single cell and a solid oxide electrolyzer including a single cell.

In order to achieve the above object, the present invention,

As a solid oxide electrolyte,

It includes a multi-layered electrolyte layer between the anode and the air electrode, and the multi-layered electrolyte layer consists of at least three layers, and two types of electrolyte layers having different coefficients of thermal expansion are sequentially stacked. It provides a solid oxide electrolyte, characterized in that the structure.

In addition, the present invention,

It includes the step of sequentially laminating an electrolyte layer of a multilayer structure consisting of at least three layers on the anode,

The multi-layered electrolyte layer provides a method of manufacturing a solid oxide electrolyte, characterized in that a structure in which two kinds of electrolyte layers having different coefficients of thermal expansion are sequentially stacked.

In addition, the present invention,

It provides a unit cell comprising the solid oxide electrolyte.

In addition, the present invention,

It provides a solid oxide fuel cell including the unit cell.

In addition, the present invention,

It provides a solid oxide electrolyzer comprising the unit cell.

According to the solid oxide electrolyte including the multi-repeated thin film electrolyte layer of the present invention, the stress of the electrolyte layers adjacent to each other can be stably distributed due to the difference in the coefficient of thermal expansion at the interface adjacent to each other in the electrolyte layer of the multilayer structure. .

Accordingly, it is possible to reduce the thermal shock that may occur in the electrolyte layer during the heating and operation of the solid oxide fuel cell or solid oxide electrolyzer, and through the formation of an ABAB-type electrolyte structure, which is a form of the multi-repetitive electrolyte proposed in the present invention. Structurally, a solid oxide electrolyte having improved thermal durability, a method of manufacturing the same, a unit cell including the same, a solid oxide fuel cell including the unit cell, and a solid oxide electrolyzer including the unit cell may be provided.

1 is a diagram showing an internal stress distribution diagram of a conventional AB type thin film electrolyte.
2 is a schematic diagram of a single cell into which a solid oxide electrolyte having an ABAB-type electrolyte layer according to the present invention is introduced.
3 is a diagram showing an internal stress distribution diagram of a solid oxide electrolyte having an ABAB type electrolyte layer according to the present invention.
4 is a photograph taken with a scanning electron microscope (SEM) of a cross section of the solid oxide cell after operation of the solid oxide electrochemical cell in order to confirm the cross-sectional structure of the solid oxide cell prepared in Example. FIG. 4(a) is a photograph showing a cross-section of a solid oxide fuel cell to which the ABAB-type thin film electrolyte of the embodiment was applied, and FIG. 4(b) is an enlarged photograph showing the microstructure of the cross-section of the ABAB-type thin film electrolyte of the embodiment.
5 is a photograph taken with a scanning electron microscope (SEM) of a cross section of the solid oxide cell after operation of the solid fuel cell in order to confirm the cross-sectional structure of the solid oxide cell prepared in Comparative Example.
6 is a graph showing the results of a performance test of the solid oxide fuel cell cell prepared in Example, and is a graph showing the output of a unit cell.
7 is a graph showing the results of a performance test of the solid oxide fuel cell cell prepared in Example, and is a graph showing the resistance of a unit cell.
8 is a graph showing the output of the solid oxide fuel cell cell manufactured in Comparative Example.

In the present invention, various modifications may be made and various embodiments may be provided, and specific embodiments will be illustrated in the drawings and described in detail in the detailed description.

However, this is not intended to limit the present invention to a specific embodiment, it should be understood to include all changes, equivalents, and substitutes included in the spirit and scope of the present invention. In describing the present invention, when it is determined that a detailed description of a related known technology may obscure the subject matter of the present invention, a detailed description thereof will be omitted.

The terms used in the present application are only used to describe specific embodiments, and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise.

In the present invention, terms such as “comprise” or “have” are intended to designate the presence of features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, but one or more other features. It is to be understood that the presence or addition of elements, numbers, steps, actions, components, parts, or combinations thereof, does not preclude in advance the possibility of the presence or addition.

The present invention relates to a solid oxide electrolyte including a multi-repeated thin film electrolyte layer, a method of manufacturing the same, a unit cell including the same, a solid oxide fuel cell including the unit cell, and a solid oxide electrolyzer including the unit cell.

In a conventional solid oxide fuel cell or solid oxide electrolyzer having an A-B type thin film electrolyte structure, an internal stress at the interface between A and B is formed as shown in FIG. 1 at a high operating temperature of 400° C. or higher due to a difference in thermal expansion coefficient. Accordingly, both of the electrolyte layers are subjected to a force to be convexly bent while an expansion stress is applied from an upper side and a compressive stress is applied from a lower side, which causes structural instability.

That is, in the case of the conventional AB type thin-film electrolyte, the thickness is very thin as a few micrometers or less, and the high-aspect ratio is very large, so even a slight difference in the coefficient of thermal expansion causes the shear strain in the bending direction due to the stress distribution inside the thin film. There was a problem that was caught and thermally unstable.

Accordingly, the present invention includes a solid oxide electrolyte including an electrolyte layer having a multi-repetitive structure capable of solving problems such as low reproducibility and durability of a thin film electrolyte due to the above problems, a method of manufacturing the same, a unit cell including the same, and a unit cell. It is intended to provide a solid oxide electrolyzer including a solid oxide fuel cell and a single cell.

Particularly, in the solid oxide electrolyte including the thin film electrolyte layer having a multi-repetition structure according to the present invention, stresses in the electrolyte layers adjacent to each other can be stably distributed due to a difference in coefficient of thermal expansion at an interface adjacent to each other. Accordingly, it is possible to reduce the thermal shock of the electrolyte layer that may occur during the heating and operation of the solid oxide fuel cell and the electrolytic cell, and structurally improved durability through the formation of an ABAB-type electrolyte structure, which is a form of a multi-repetition structure. There is an advantage to be able to provide a battery and an electrolyzer. Meanwhile, hereinafter, the electrolyte of the present invention will be described later as having an A-B-A-B type or first to fourth electrolyte layers, but the number of electrolyte layers is not limited thereto.

Hereinafter, the present invention will be described in detail.

FIG. 2 is a schematic diagram of a single cell in which a solid oxide electrolyte having an ABAB-type electrolyte layer according to the present invention is introduced, and FIG. 3 is a diagram showing an internal stress distribution diagram of a solid oxide electrolyte having an ABAB-type electrolyte layer according to the present invention. to be.

As shown in Fig. 2, the solid oxide electrolyte of the present invention includes a multilayer structure between the anode and the cathode. In this case, the multilayered electrolyte layer may be composed of at least three layers, and two types of electrolyte layers having different coefficients of thermal expansion may be sequentially stacked.

Referring to FIG. 3, the internal stress of the electrolyte layer of the multilayer structure of the present invention will be described. Referring to FIG. 3, in the A1-B1-A2-B2 type electrolyte layer, stresses between the B1 layer and the A2 layer are stably distributed due to the difference in the coefficient of thermal expansion at the interfaces A1-B1, B1-A2, and A2-B2. . In particular, it can be expected that the A2 electrolyte is stabilized together while B1 is stabilized by the compressive stress.

The interfacial stress of the electrolyte layer can be calculated as follows.

σ = Eε

E: Young's modulus, ε: strain

On the other hand, since the strain is generated by thermal expansion, the following equation is established.

ε = ΔL/L0 = αΔT

α: Coefficient of thermal expansion, ΔT: temperature difference (T _cell -T ₀ >0)

Therefore, the stress σ = Eε = EαΔT.

In the case of layer A is yttria-stabilized zirconia (YSZ) and layer B is gadolinium-doped ceria (GDC), α _B > α _A, so ΔL _B > ΔL _A. Stress occurs in the opposite direction of the strain. Accordingly, the direction of internal stress applied at the interface of the electrolyte layer is distributed as shown in FIG. 3.

For reference, the present invention has found excellent effects in high electromotive force and electrochemical performance due to high thermal durability compared to the prior art due to the above-described structural features, which will be described later in experimental examples. The multi-repeated solid oxide electrolyte layer of the present invention has a structure in which a first electrolyte layer, a second electrolyte layer, and a third electrolyte layer are sequentially stacked on a fuel electrode. In this case, the second electrolyte layer is a material different from the first and third electrolyte layers and has a different coefficient of thermal expansion.

In addition, the first electrolyte layer and the third electrolyte layer may have the same coefficient of thermal expansion.

Further, a structure in which a fourth electrolyte layer is stacked on a third electrolyte layer, and the fourth electrolyte layer may have the same coefficient of thermal expansion as that of the second electrolyte layer.

More specifically, the solid oxide electrolyte of the present invention may satisfy Equation 1 below at an average temperature of 400°C to 900°C.

[Equation 1]

│CTE _a -CTE _b │≤10×10 ^-6 /K

In Equation 1, CTE _a is the thermal expansion coefficient of the first and third electrolyte layers, and CTE _b is the thermal expansion coefficient of the second and fourth electrolyte layers.

_{If the value of │CTE a} -CTE _b │ exceeds 10×10 ^-6 /K in the above range, the difference in the coefficient of thermal expansion of each electrolyte layer is too large. Since structural problems such as cracks may occur, it is preferable that the _{range of │CTE a} -CTE _b │ is 10×10 ^{-6 /K or less.}

That is, when the solid oxide electrolyte satisfies Equation 1, due to the difference in the coefficient of thermal expansion at the interface where each electrolyte layer contacts, it can be structurally stabilized by suppressing the generation of stress and thermal fatigue due to the difference in the coefficient of thermal expansion of different elements. .

The first and third electrolyte layers are yttria-stabilized zirconia (YSZ, Yttria-stabilized zirconia), scandia-stabilized zirconia (SSZ), yttrium-doped barium zirconate (BZY, yttrium doped barium). zirconate), yttrium doped barium cerate (BCY), a solid solution of yttrium-doped barium zirconate and barium serate (BZCY), or strontium manganese-doped lanthanum gallate (LSGM) ), and the second and fourth electrolyte layers are gadolinium-doped ceria (GDC), samarium-doped ceria (SDC), and yttrium-doped ceria (YDC, Yittrium- Doped ceria) or lanthanum-doped ceria (LDC).

Specifically, the first and third electrolyte layers are YSZ (Zr _0.84 Y _0.16 O _2-δ ), SSZ ( Zr _1-x Sc _x O _2-δ ), BZY ( BaZr _0.8 Y _0.2 O _3-δ ) , BCY ( BaCe _0.8 Y _0.2 O _3-δ ), BZCY ( BaZr _x Ce _0.8-x Y _0.2 O _3-δ ) or LSGM ( La _0.8 Sr _0.2 Ga _0.8 Mg _0.2 O _3-δ ), The second and fourth electrolyte layers are GDC (Ce _0.9 Gd _0.1 O _2-δ ), SDC ( Sm _x Ce _1-x O _2-δ ), YDC ( Y _x Ce _1-x O _2-δ ) or LDC ( La _x Ce _1-x O _2-δ ) may be included. For example, the first and third electrolyte layers may include yttria-stabilized zirconia (Zr _0.84 Y _0.16 O _2-δ ), and the second and fourth electrolyte layers Gadolinium-doped ceria (Gadolinium-doped ceria, Ce _0.9 Gd _0.1 O _2-δ ) may be included.

In this case, the thickness of the first and third electrolyte layers may be 0.1 to 10 μm, and the thickness of the second and fourth electrolyte layers may be 0.1 to 5 μm.

If the thickness of the first and third electrolyte layers is less than 0.1 μm, a sufficiently dense electrolyte thin film cannot be obtained with the thin film coating technology described above, and if it exceeds 10 μm, it is out of the range of the thin film electrolyte. It may not be suitable for solid oxide electrolytes. In addition, when the thickness of the second and fourth electrolyte layers is less than 0.1 μm, as described above, a dense electrolyte thin film cannot be obtained, and when it exceeds 5 μm, it is outside the range of the buffer layer, so it is suitable for the solid oxide electrolyte of the present invention. I can't.

In a specific embodiment, the solid oxide electrolyte may include a first electrolyte layer, a second electrolyte layer, and a third electrolyte layer, wherein the first and third electrolyte layers are gadolinium-doped ceria (GDC). ceria), samarium-doped ceria (SDC), yttrium-doped ceria (YDC), or lanthanum-doped ceria (LDC), and the second electrolyte layer, Yttria-stabilized zirconia (YSZ), scandia-stabilized zirconia (SSZ), yttrium doped barium zirconate (BZY), yttrium doped barium Serate (BCY, yttrium doped barium cerate), a solid solution of yttrium doped barium zirconate and barium serate (BZCY), or strontium manganese-doped lanthanum gallate (LSGM).

For example, the first and third electrolyte layers may include gadolinium-doped ceria (GDC), and the second electrolyte layer is yttria-stabilized zirconia (YSZ, Yttria-stabilized ceria). zirconia).

In this case, the thickness of the first electrolyte layer and the third electrolyte layer may be 0.1 to 5 μm, and the thickness of the second electrolyte layer may be 0.1 to 10 μm.

In addition, the present invention,

It includes the step of sequentially laminating an electrolyte layer of a multilayer structure consisting of at least three layers on the anode,

The multi-layered electrolyte layer provides a method of manufacturing a solid oxide electrolyte, characterized in that a structure in which two kinds of electrolyte layers having different coefficients of thermal expansion are sequentially stacked.

Specifically, the step of sequentially laminating the multi-layered electrolyte layer includes a physical vapor deposition method (PVD, Physical Vapor Deposition), a chemical vapor deposition method (CVD, Chemical Vapor Deposition), a chemical solution deposition method (CSD, Chemical Solution Deposition), and spraying. It can be performed by any one thin film process selected from the group consisting of a spray pyrolysis, a sol-gel method, a spray coating method, and a spin coating method.

In addition, the present invention

It provides a unit cell comprising the solid oxide electrolyte.

Specifically, the unit cell may mean a unit cell composed of a fuel electrode, an electrolyte, and an air electrode.

Here, in the unit cell, the anode may be formed of Yttria Stabilized Zirconia (hereinafter referred to as'YSZ') to which nickel oxide (hereinafter, referred to as'NiO') is added.

The unit cell is stacked on the anode and the anode, and is stacked on top of the electrolyte layer and the electrolyte layer including a first electrolyte layer consisting of at least two layers, and a second electrolyte layer positioned between the first and third electrolyte layers And a cathode, and the second electrolyte layer may have a different coefficient of thermal expansion than the first electrolyte layer.

Since the electrolyte is the same as described above, a detailed description will be omitted.

In the case of the air electrode, most common air electrodes can be used, and in this example, it was made of LSCF-GDC. LSCF-GDC is a composite material of LSCF, which is a cathode catalyst, and GDC, which is a material for a buffer layer, and was coated and heat treated through screen printing. LSCF is Lanthanum Strontium Cobalt Ferrite, and GDC is Gadolinium-Doped Ceria.

In addition, the anode, a porous support; And an anode functional layer stacked on the porous support. In an exemplary embodiment of the present invention, a porous substrate having a single-layer structure is prepared by sintering a NiO-YSZ tape, and a spin coating process is performed using a paste of the same material on the porous substrate to heat-treat the anode functional layer.

In addition, the present invention provides a solid oxide fuel cell including the unit cell and a solid oxide electrolyzer including the unit cell. Since the structure of the unit cell is the same as described above, a detailed description of the unit cell will be omitted.

In particular, the solid oxide fuel cell and the solid oxide electrolyzer according to the present invention contain a solid oxide electrolyte including a multi-repeated thin film electrolyte layer, so that the solid oxide fuel cell and the solid oxide electrolyzer contain a solid oxide electrolyte. It can reduce the thermal shock that may occur. In addition, the solid oxide fuel cell and the solid oxide electrolyzer may structurally improve thermal durability.

Hereinafter, the present invention will be described in more detail through examples and experimental examples.

However, the following Examples and Experimental Examples are merely illustrative of the present invention, and the contents of the present invention are not limited to the following Examples and Experimental Examples.

<Example>

Anode manufacturing

A single-layer porous substrate made by sintering a NiO-YSZ tape at 1000° C. for 4 hours was prepared. Then, after the spin coating process using a paste of the same material on the porous substrate, heat treatment was performed at 1300 degrees Celsius for 4 hours to prepare a functional anode layer. The thickness of the substrate is about 400 µm, and the thickness of the functional layer is about 10 to 20 µm.

Electrolyte layer manufacturing

An electrolyte was laminated on the anode functional layer. First, an YSZ layer, a GDC layer, an YSZ layer, and a GDC layer were sequentially stacked on the anode functional layer.

Specifically, an A-B-A-B-type electrolyte layer was formed on the anode by depositing at a process pressure of 5 mTorr using sputtering, a kind of physical vapor deposition in order. At this time, the YSZ layer deposited on the anode was 1 μm, and the GDC layer was 300 nm.

Air cathode manufacturing

The cathode was screen-printed on the surface of the electrolyte using a composite paste _{of La 0.6} Sr _0.4 Co _0.2 Fe _0.8 O _3-δ and Ce _0.9 Gd _0.1 O _2-δ at a weight ratio of 6:4. The cathode was manufactured by sintering through heat treatment at 970°C for 2 hours, and the total thickness of the cathode was about 20 μm.

Accordingly, a unit cell including an A-B-A-B type electrolyte was prepared.

<Comparative Example>

A unit cell was manufactured in the same manner as in Example, except that the A-B type electrolyte layer was included.

<Experimental Example>

Experimental Example 1. Photographing the cross-sectional structure of a solid oxide cell

In order to confirm the cross-sectional structure of the solid oxide cells prepared in Examples and Comparative Examples, photographs were taken with a scanning electron microscope (SEM).

And, the results are shown in FIGS. 4 and 5.

First, FIG. 4 is a photograph taken with a scanning electron microscope (SEM) of a cross section of the solid oxide cell after the operation of the solid oxide electrochemical cell in order to confirm the cross-sectional structure of the solid oxide cell prepared in Example. Figure 4(a) is a photograph showing a cross-section of a solid oxide fuel cell to which the A-B-A-B type thin film electrolyte of the embodiment is applied, and FIG. 4(b) is an enlarged photograph showing the microstructure of the cross-section of the A-B-A-B type thin film electrolyte of the embodiment.

Referring to FIG. 4, it can be seen that the solid oxide cell prepared in the embodiment does not cause cracks or peeling in the thin film electrolyte.

5 is a photograph taken with a scanning electron microscope (SEM) of a cross section of the solid oxide cell after operation of the solid oxide electrochemical cell in order to confirm the cross-sectional structure of the solid oxide cell prepared in Comparative Example.

Referring to FIG. 5, it can be seen that cracks and peeling phenomena occur on the surface of the thin film electrolyte and are separated from the substrate.

This is, due to the small difference in the coefficient of thermal expansion of the A-B type, it seems that the internal stress generated at the A-B interface cracks and peels due to thermal shock.

Experimental Example 2. Evaluation of electrochemical performance of solid oxide cell

The electrochemical performance of the solid oxide cells prepared in Examples and Comparative Examples were evaluated. Specifically, the change in current density was measured while changing the voltage flowing through the unit cell using a DC electronic load and a DC power supply.

The performance of the unit cell was measured while changing the operating temperature of the examples to 550° C., 600° C., and 650° C. In addition, hydrogen (H ₂ ) containing 3% moisture (H ₂ O) flows through the anode at a rate of 100 ml/min, and air flows through the cathode at a rate of 150 ml/min, while the current-voltage ( IV) After measuring the curve, the electrochemical resistance of the unit cell was measured by impedance measurement immediately after the open circuit state.

Meanwhile, in the comparative example, the performance of the unit cell was measured at an operating temperature of 650° C., and the remaining experimental conditions were the same as in the example.

And, the results are shown in Figs. 6 to 8. With reference to FIGS. 6 to 8, the results of the performance test according to embodiments of the present invention will be briefly described.

For reference, FIG. 6 is a graph showing the performance test results of the solid oxide fuel cell cell manufactured in the Example, a graph showing the output of the unit cell, and FIG. 7 is an electrochemical diagram of the solid oxide fuel cell cell manufactured in the Example. It is a graph showing the resistance.

Referring to FIGS. 6 and 7, the solid oxide fuel cell prepared in the Example has an open circuit voltage close to the theoretical value (~ 1.1 V), and shows sufficiently high performance without the use of a new material.

8 is a graph showing the output of the solid oxide fuel cell cell manufactured in Comparative Example. Referring to FIG. 8, it was confirmed that the solid oxide fuel cell cell prepared in the comparative example exhibited remarkably low electromotive force due to cracking and peeling of the electrolyte, and accordingly, the output value was significantly lower than that of the example.

This may provide a solid oxide electrochemical cell capable of stabilizing a stress distribution due to thermal shock by including an A-B-A-B type electrolyte having a different thermal stress coefficient. Accordingly, it is possible to secure a sufficient contact area at the interface between the anode and the cathode and between each layer of the electrolyte, thereby suppressing the movement resistance of oxygen ions and expanding the reaction field, resulting in electromotive force and electrochemical performance. It seems to be improving.

From these results, it can be seen that the solid oxide electrochemical cell including the multi-repetitive structure electrolyte according to the present invention has superior thermal durability and thus electrochemical performance compared to the conventional solid oxide electrochemical cell.

Claims (18)

It includes a multi-layered electrolyte layer between the anode and the air electrode, and the multi-layered electrolyte layer consists of at least three layers, and two types of electrolyte layers having different coefficients of thermal expansion are sequentially stacked. Solid oxide electrolyte, characterized in that the structure.
The method of claim 1,
The electrolyte layer of a multilayer structure is a structure in which a first electrolyte layer, a second electrolyte layer, and a third electrolyte layer are sequentially stacked on a fuel electrode,
The solid oxide electrolyte, wherein the second electrolyte layer has a different coefficient of thermal expansion than the first and third electrolyte layers.
The method of claim 2,
A solid oxide electrolyte, wherein the first electrolyte layer and the third electrolyte layer have the same coefficient of thermal expansion.
The method of claim 2,
It is a structure in which a fourth electrolyte layer is stacked on the third electrolyte layer,
The solid oxide electrolyte, wherein the fourth electrolyte layer has the same coefficient of thermal expansion as the second electrolyte layer.
The method of claim 4,
The solid oxide electrolyte is a solid oxide electrolyte, characterized in that it satisfies the following formula 1 at an average temperature of 400 to 900°C:

[Equation 1]
│CTE _a -CTE _b │≤10×10 ^-6 /K
In Equation 1, CTE _a is the thermal expansion coefficient of the first and third electrolyte layers, and CTE _b is the thermal expansion coefficient of the second and fourth electrolyte layers.
The method of claim 4,
The first and third electrolyte layers are yttrium-stabilized zirconia (YSZ, Yttria-stabilized zirconia), scandia-stabilized zirconia (SSZ), yttrium-doped barium zirconate (BZY, yttrium doped barium zirconate). ), yttrium doped barium cerate (BCY), a solid solution of yttrium doped barium zirconate and barium serate (BZCY) or strontium manganese-doped lanthanum gallate (LSGM) Including,
The second and fourth electrolyte layers are gadolinium-doped ceria (GDC), samarium-doped ceria (SDC), yttrium-doped ceria (YDC), or lanthanum-doped ceria. A solid oxide electrolyte comprising (LDC, Lanthanum-Doped Ceria).
The method of claim 4,
The first electrolyte layer and the third electrolyte layer include yttria-stabilized zirconia (YSZ, Yttria-stabilized zirconia),
The second and fourth electrolyte layers are solid oxide electrolytes, characterized in that they contain gadolinium-doped ceria (GDC).
The method of claim 4,
The thickness of the first electrolyte layer and the third electrolyte layer is 0.1 to 10 μm,
The solid oxide electrolyte, characterized in that the thickness of the second electrolyte layer and the fourth electrolyte layer is 0.1 to 5 ㎛.
The method of claim 2, wherein the first and third electrolyte layers are gadolinium-doped ceria (GDC), samarium-doped ceria (SDC), and yttrium-doped ceria (YDC). Doped ceria) or Lanthanum-Doped Ceria (LDC),
The second electrolyte layer is yttria-stabilized zirconia (YSZ, Yttria-stabilized zirconia), scandia-stabilized zirconia (SSZ), yttrium-doped barium zirconate (BZY, yttrium doped barium zirconate), yttrium doped. Containing yttrium doped barium cerate (BCY), a solid solution of yttrium doped barium zirconate and barium serate (BZCY), or strontium manganese-doped lanthanum gallate (LSGM). Solid oxide electrolyte, characterized in that.
The method of claim 2, wherein the first and third electrolyte layers include gadolinium-doped ceria (GDC),
The second electrolyte layer is a solid oxide electrolyte comprising yttria-stabilized zirconia (YSZ).
The method of claim 9,
The thickness of the first electrolyte layer and the third electrolyte layer is 0.1 to 5 μm,
Solid oxide electrolyte, characterized in that the thickness of the second electrolyte layer is 0.1 to 10 ㎛.
It includes the step of sequentially laminating an electrolyte layer of a multilayer structure consisting of at least three layers on the anode,
The method of manufacturing a solid oxide electrolyte, wherein the multi-layered electrolyte layer has a structure in which two types of electrolyte layers having different coefficients of thermal expansion are sequentially stacked.
The method of claim 12,
The steps of sequentially laminating multi-layered electrolyte layers include physical vapor deposition (PVD), chemical vapor deposition (CVD), chemical solution deposition (CSD), and spray pyrolysis. ), a sol-gel method, a spray coating method, and a spin coating method.
A single cell comprising the solid oxide electrolyte according to any one of claims 1 to 11.
The method of claim 14,
The unit cell, the fuel electrode;
An electrolyte layer stacked on the anode and including a first electrolyte layer comprising at least two layers and a second electrolyte layer positioned between the first and third electrolyte layers; And
An air electrode stacked on the electrolyte layer; Including,
The unit cell, wherein the second electrolyte layer has a different coefficient of thermal expansion than the first electrolyte layer.
The method of claim 14,
The anode, a porous support; And an anode functional layer stacked on the porous support.
A solid oxide fuel cell comprising the unit cell according to claim 14.
A solid oxide electrolyzer comprising the unit cell according to claim 14.

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