KR101281772B1 - Solid oxide fuel cell and method of fabricating the same - Google Patents

Abstract

A cathode, an anode having a fuel gas inlet and a fuel gas outlet on each side, and an electrolyte comprising a solid oxide, the anode having a surface coated with a catalyst, the anode coated with the catalyst having the fuel gas inlet A solid oxide fuel cell, and a method for producing the same, having a density gradient of increasing or decreasing catalyst density from the side toward the fuel gas outlet side is provided.

Description

Solid oxide fuel cell and its manufacturing method {SOLID OXIDE FUEL CELL AND METHOD OF FABRICATING THE SAME}

The present disclosure relates to a solid oxide fuel cell and a method of manufacturing the same.

A solid oxide fuel cell (SOFC) is a device that converts the chemical energy of various fuels into electrical energy, and cathodes (also called "air electrodes") on both sides of electrolytes made of solid oxides that pass oxygen ions well. And an anode (also called "fuel electrode") are located and operated by supplying air and fuel to the cathode and the anode, respectively.

Specifically, the oxygen ions produced by the reduction reaction of oxygen at the cathode react with the hydrogen supplied to the anode through the electrolyte to generate electricity, heat and water.

In general, SOFCs have a temperature gradient where the temperature on the fuel gas outlet side at the anode side is higher than the temperature on the fuel gas inlet side. SOFC for the internal reforming reaction is a reforming reaction of the fuel in the interior, methane gas and the like supplied to the anode is due to the nature of the SOFC operating at a high temperature, most of the participation in the reforming reaction at the anode on the fuel gas inlet side. In this case, since the reforming reaction is thermodynamically endothermic, the temperature at the fuel gas inlet side is lowered, resulting in a deeper temperature gradient across the SOFC stack.

In order to alleviate this temperature gradient, a technique of not applying an anode serving as a catalyst for the reforming reaction at the fuel gas inlet side has been published, but it is applicable only to an electrolyte-supported SOFC, but is not applicable to an anode-supported SOFC. It is not possible and also reduces the idle area of the cell, thereby reducing the power output per cell.

One aspect of the present invention is to provide a solid oxide fuel cell having excellent cell performance by alleviating the temperature gradient of the entire solid oxide fuel cell stack.

Yet another aspect of the present invention is to provide a solid oxide fuel cell stack including the solid oxide fuel cell.

Another aspect of the present invention is to provide a method for producing the solid oxide fuel cell.

One aspect of the present invention includes a cathode: an anode having a fuel gas inlet and a fuel gas outlet on each side thereof, and an electrolyte comprising a solid oxide, the anode being coated with a catalyst and having a surface coated with the catalyst. The anode provides a solid oxide fuel cell having a density gradient that increases or decreases the catalyst density from the fuel gas inlet side to the fuel gas outlet side.

The density gradient may comprise a discrete form or a continuous form.

The catalyst is a catalyst comprising Ni; A subcatalyst comprising Fe ₂ O ₃ , TiO ₂ , Cr ₂ O _3, or a combination thereof; Or combinations thereof.

The density ratio of the cocatalyst coated on the surface of the anode may be 5 to 100%, and the density ratio of the subcatalyst coated on the surface of the anode may be 0 to 95%.

The anode coated with the cocatalyst may have a density gradient in which a cocatalyst density increases from the fuel gas inlet side toward the fuel gas outlet side, and the anode coated with the subcatalyst goes from the fuel gas inlet side toward the fuel gas outlet side. It may have a density gradient that decreases the density.

The solid oxide fuel cell may comprise an internally reformed solid oxide fuel cell.

The solid oxide fuel cell may include a high temperature solid oxide fuel cell or a low temperature solid oxide fuel cell.

Using another screen printing plate making of the present invention, a method of manufacturing a solid oxide fuel cell comprising coating a surface of an anode having a fuel gas inlet and a fuel gas outlet on both sides with a density gradient as a catalyst To provide.

The screen printing plate making may include masking the entire screen original with a mask; Forming a pattern on the masked screen disc; And removing a mask of the formed pattern portion to form a patterned region in which a catalyst is coated, and may be manufactured such that a ratio of the patterned region changes from one side of the screen printing plate to the other.

The coating step may be performed using the screen printing plate making the ratio of the patterning area is higher or lower from the fuel gas inlet side to the fuel gas outlet side.

The catalyst is a catalyst comprising Ni; A subcatalyst comprising Fe ₂ O ₃ , TiO ₂ , Cr ₂ O _3, or a combination thereof; Or combinations thereof.

Coating with the cocatalyst may be performed using the screen printing plate making the ratio of the patterning area increase from the fuel gas inlet side to the fuel gas outlet side, and coating with the subcatalyst is the fuel gas inlet side At the fuel gas outlet side may be performed using the screen printing plate making the ratio of the patterning area is lowered.

According to another aspect of the present invention, a first solid oxide fuel cell of any one of a fuel cell, a second solid oxide fuel cell formed in the same manner as the first solid oxide fuel cell, and the first solid oxide fuel cell and the second A solid oxide fuel cell stack is provided between a solid oxide fuel cell and comprising a separator comprising a cathode side gas passage and an anode side gas passage.

Other aspects of the present invention are included in the following detailed description.

By reducing the temperature gradient of the entire solid oxide fuel cell stack, it is possible to implement a solid oxide fuel cell having excellent cell performance.

1 is a schematic view showing the structure of a solid oxide fuel cell according to one embodiment.
2 is a top view illustrating a structure of a solid oxide fuel cell according to an embodiment.
3 shows a discrete form of density gradient of a catalyst coated on an anode surface according to one embodiment.
4 is a diagram showing a continuous form of a density gradient of a catalyst coated on an anode surface according to one embodiment.
5 is a schematic diagram illustrating coating an anode surface with a cocatalyst according to one embodiment.
6 is a schematic view showing coating of an anode surface with a cocatalyst according to one embodiment.
7 is a schematic view showing the structure of a solid oxide fuel cell stack according to one embodiment.

Hereinafter, embodiments of the present invention will be described in detail. However, it should be understood that the present invention is not limited thereto, and the present invention is only defined by the scope of the following claims.

In the drawings, the thickness is enlarged to clearly represent the layers and regions. Like parts are designated with like reference numerals throughout the specification. Whenever a portion of a layer, film, region, plate, or the like is referred to as being "on" another portion, it includes not only the case where it is "directly on" another portion, but also the case where there is another portion in between. Conversely, when a part is "directly over" another part, it means that there is no other part in the middle.

Unless otherwise specified herein, the term "side" refers to being located in proximity to the anode, fuel gas inlet or fuel gas outlet.

Hereinafter, a solid oxide fuel cell according to an embodiment will be described with reference to the drawings.

1 is a schematic view showing a structure of a solid oxide fuel cell according to an embodiment, and FIG. 2 is a top view showing a structure of a solid oxide fuel cell according to an embodiment.

Referring to FIG. 1, a solid oxide fuel cell 10 according to an embodiment includes an anode 12, a cathode 16, and a solid oxide positioned between the anode 12 and the cathode 16. Electrolyte 14.

Referring to FIG. 2, a solid oxide fuel cell 10 according to an embodiment may include a fuel gas inlet 13 positioned on both sides of the anode 12 between an anode 12 and an electrolyte 14, and A fuel gas outlet 15.

2 illustrates an electrolyte-supported solid oxide fuel cell as an example, but is not limited thereto. That is, the fuel gas inlet and the fuel gas outlet may be included inside the unit cell or may be included outside.

The anode 12 has a surface coated with a catalyst, the surface has a density gradient of different density for each site.

Specifically, the anode 12 of the portion adjacent to the fuel gas outlet 15 at the anode 12 surface of the portion adjacent to the fuel gas inlet 13, that is, the anode 12 surface on the fuel gas inlet 13 side. ), That is, the density gradient of the catalyst density increases or decreases toward the surface of the anode 12 on the fuel gas outlet 15 side.

The form of the density gradient can be described with reference to FIGS. 3 and 4.

3 is a diagram showing a discrete form of density gradient of a catalyst coated on the anode surface according to one embodiment, and FIG. 4 is a continuous view of the density gradient of a catalyst coated on the anode surface according to one embodiment. ) Is a figure showing the shape.

Referring to FIGS. 3 and 4, the density gradient may have a discontinuous form in which a difference in density occurs for each section based on a predetermined interval of boundary points on the anode surface, or continuously without density boundary points at the anode surface. It may have a continuous form where the difference of.

In this way, by coating the anode surface with a catalyst having a different density for each site, it is possible to control the location where the reforming reaction occurs, thereby alleviating the temperature gradient throughout the solid oxide fuel cell stack.

The catalyst is a catalyst comprising Ni; A subcatalyst comprising Fe ₂ O ₃ , TiO ₂ , Cr ₂ O _3, or a combination thereof; Or combinations thereof.

In other words, the anode surface may be coated with a cocatalyst, may be coated with a cocatalyst, or may be coated with a mixture of the cocatalyst and the cocatalyst. Specifically, the density ratio of the positive catalyst coated on the anode surface may be 5 to 100%, and the density ratio of the subcatalyst may be 0 to 95%.

Specifically, when the anode surface is coated with the cocatalyst, the cocatalyst density may increase from the anode surface of the fuel gas inlet side to the anode surface of the fuel gas outlet side. In this case, since the anode surface on the fuel gas inlet side is coated with the minimum cocatalyst density, the activity and endothermic amount of the reforming reaction are minimized. On the contrary, since the anode surface on the fuel gas outlet side is coated with the maximum cocatalyst density, the activity and endothermic amount of the reforming reaction are maximized. As a result, the reforming reaction mainly occurs at the fuel gas outlet side, which is a high temperature portion, thereby lowering the temperature of the hot spot on the fuel gas outlet side, thereby alleviating intensification of the temperature gradient.

In addition, when the anode surface is coated with the subcatalyst, the subcatalyst density may be reduced from the fuel gas inlet side toward the fuel gas outlet side. In this case, since the anode surface on the fuel gas inlet side is coated with the maximum subcatalyst density, the activity and endothermic amount of the reforming reaction are minimized. On the contrary, since the anode surface on the fuel gas outlet side is coated with a minimum subcatalyst density, the activity and endothermic amount of the reforming reaction are maximized. Accordingly, the reforming reaction mainly occurs at the fuel gas outlet side, which is a high temperature portion, thereby lowering the temperature of the hot spot on the fuel gas outlet side, so that a deepening of the temperature gradient can be alleviated.

The anode 12 is a metal phase such as nickel, a noble metal (eg Pt); And zirconia, stabilized zirconia (e.g. zirconia stabilized with yttria, scandia, etc.), ceria, doped ceria (e.g. lanthanum, gadolinium, samarium) Cermet) including a ceramic phase including ceria doped), or the like, may be used.

The electrolyte 14 may be stabilized zirconia (eg, zirconia stabilized with yttria, scandia, etc.), doped ceria, an ion conductive ceramic material, and the like.

The cathode 16 may be formed of lanthanum strontium manganite (LSM), lanthanum strontium iron cobaltite (LSCF), lanthanum strontium manganese cobaltite, and electroconductive ferroelectric such as LSMC. Skytight materials can be used.

As described above, the anode surface has a density gradient of the catalyst and the coated solid oxide fuel cell may be mainly applied to an internal reforming solid oxide fuel cell.

The solid oxide fuel cell may also be applied to both a high temperature solid oxide fuel cell or a low temperature solid oxide fuel cell. Specifically, the high temperature solid oxide fuel cell may coat the anode surface with a subcatalyst because the reforming reaction occurs quickly, and the low temperature solid oxide fuel cell may coat the anode surface with the cocatalyst because the reforming reaction occurs slowly.

The solid oxide fuel cell may be manufactured by coating a surface of an anode having a fuel gas inlet and a fuel gas outlet on both sides with a catalyst having a density gradient.

The coating may be performed by screen printing, and the screen printing is a method of coating a catalyst on the surface of the anode using screen printing.

The screen printing method may be performed as follows.

First, screen printing is produced. The screen printing plate making may include masking the entire screen original with a mask; Forming a pattern on the masked screen disc; And removing the mask of the formed pattern to form a patterning region coated with a catalyst. In this case, the ratio of the patterning area may be changed from one side of the screen printing plate to the other.

Thereafter, the screen printing plate is placed on the surface of the anode, and then a paste including a catalyst is applied to the screen printing plate to perform coating. The coating is then completed by removing the screen printing plate making.

The coating may be performed by using a screen printing plate making such that the ratio of the patterning area to which the catalyst is coated is gradually increased or decreased from the fuel gas inlet side to the fuel gas outlet side.

Hereinafter, a method of coating the anode surface with a catalyst will be described in detail with reference to the accompanying drawings.

5 is a schematic diagram illustrating coating an anode surface with a cocatalyst according to one embodiment. FIG. 5 is an example of a method of coating with a cocatalyst, and illustrates a coating having a density gradient of four sections using a screen printing plate made by changing the ratio of the patterning area into four types, but is not limited thereto.

Referring to FIG. 5, first, an anode 12 having fuel gas inlet 13 and fuel gas outlet 15 located on both sides thereof is prepared, and then a screen printing plate 40 is placed on the anode 12. A paste containing a subcatalyst is applied and coated. The coating can be carried out from the surface of the anode 12 on the fuel gas inlet 13 side to the surface of the anode 12 on the fuel gas outlet 15 side, with the proportion of the patterning area 41 on which the catalyst is coated. This may be performed using the screen printing plate 40, which is made to be gradually lowered from the surface of the anode 12 on the fuel gas inlet 13 side to the surface of the anode 12 on the fuel gas outlet 15 side. .

In this case, the patterning region 41 may represent an opening as a region in which the catalyst is coated, and the non-patterning region 42 may represent a closed portion as a region in which the catalyst is not coated.

As described above, when the anode surface is coated with the subcatalyst by using a screen printing plate which is manufactured such that the proportion of the patterning region coated with the catalyst is gradually lowered, the subcatalyst is gradually moved from the fuel gas inlet side anode surface to the fuel gas outlet side anode surface. It may have a density gradient that decreases the density. In this case, since the anode surface on the fuel gas inlet side is coated with the maximum subcatalyst density, the activity and endothermic amount of the reforming reaction are minimized. On the contrary, since the anode surface on the fuel gas outlet side is coated with a minimum subcatalyst density, the activity and endothermic amount of the reforming reaction are maximized. As a result, the reforming reaction mainly occurs at the fuel gas outlet side, which is a high temperature portion, so that the temperature gradient can be alleviated.

6 is a schematic view showing coating of an anode surface with a cocatalyst according to one embodiment. FIG. 6 illustrates an example of a coating having a density gradient of four sections using a screen printing plate made by changing the ratio of the patterning area into four types as an example of a method of coating with a catalyst, but is not limited thereto.

Referring to FIG. 6, first, an anode 12 having fuel gas inlet 13 and fuel gas outlet 15 located on both sides thereof is prepared, and then, the screen printing plate 40 is placed on the anode 12. The paste containing the positive catalyst is applied and coated. The coating can be carried out from the surface of the anode 12 on the fuel gas inlet 13 side to the surface of the anode 12 on the fuel gas outlet 15 side, with the proportion of the patterning area 41 on which the catalyst is coated. The screen printing plate 40 may be fabricated to increase gradually from the surface of the anode 12 on the side of the fuel gas inlet 13 to the surface of the anode 12 on the side of the fuel gas inlet 15. .

As described above, when the anode surface is coated with the positive catalyst by using a screen printing plate made so that the ratio of the patterning area coated with the catalyst is gradually increased, the catalyst is gradually moved from the fuel gas inlet side anode surface to the fuel gas outlet side anode surface. It may have a density gradient that increases in density. In this case, since the anode surface on the fuel gas inlet side is coated with the minimum cocatalyst density, the activity and endothermic amount of the reforming reaction are minimized. On the contrary, since the anode surface on the fuel gas outlet side is coated with the maximum cocatalyst density, the activity and endothermic amount of the reforming reaction are maximized. As a result, the reforming reaction mainly occurs at the fuel gas outlet side, which is a high temperature portion, so that the temperature gradient can be alleviated.

As such, by using a screen printing plate with a controlled proportion of the patterning area, the catalyst can be simply coated to have a density gradient on the surface of the anode, and the density of the catalyst can be controlled on the surface of the anode for each desired portion, thereby determining the position at which the reforming reaction occurs. Control, thereby mitigating the temperature gradient across the solid oxide fuel cell stack.

Hereinafter, a structure of a solid oxide fuel cell stack including the solid oxide fuel cell will be described with reference to the drawings.

7 is a schematic view showing the structure of a solid oxide fuel cell stack according to one embodiment.

Referring to FIG. 7, a solid oxide fuel cell including an anode 12, an electrolyte 14, and a cathode 16 may be viewed as a unit cell, and a stack structure in which several unit cells are stacked may be seen. have.

Since the amount of electric energy produced by one unit cell is very limited, it is inevitable to form a stack structure in which a plurality of unit cells are stacked to utilize a fuel cell for power generation.

The solid oxide fuel cell stack 20 includes a separator 22 to prevent gas mixing while electrically connecting the anode and the cathode when connecting each unit cell.

The separator 22 may use a ferritic stainless steel sheet based on Fe—Cr, and includes a cathode-side gas flow path 28 to the cathode and an anode-side gas flow path 30 to the anode.

10: solid oxide fuel cell
12: anode
14: electrolyte
16: cathode
13: fuel gas inlet
15: fuel gas outlet
20: solid oxide fuel cell stack
22: separator
24: anode side end plate
26: cathode side end plate
28: cathode gas passage
30: gas path on the anode side
40: Screen Printing
41: patterning area
42: non-patterned area

Claims (15)

Cathode:
An anode having a fuel gas inlet and a fuel gas outlet on each side thereof: and
An electrolyte comprising a solid oxide,
The anode is coated on the surface with a catalyst,
The anode coated with the catalyst has a density gradient that increases or decreases the catalyst density from the fuel gas inlet side to the fuel gas outlet side,
The catalyst is a catalyst comprising Ni; A subcatalyst comprising Fe ₂ O ₃ , TiO ₂ , Cr ₂ O _3, or a combination thereof; Or a combination thereof. The method of claim 1,
Wherein said density gradient comprises a discrete form or a continuous form.
delete The method of claim 1,
The density ratio of the cocatalyst coated on the surface of the anode is 5 to 100%, the density ratio of the subcatalyst coated on the surface of the anode is 0 to 95%.
The method of claim 1,
And the anode coated with the cocatalyst has a density gradient in which the cocatalyst density increases from the fuel gas inlet side to the fuel gas outlet side.
The method of claim 1,
And the anode coated with the subcatalyst has a density gradient such that the subcatalyst density decreases from the fuel gas inlet side to the fuel gas outlet side.
The method of claim 1,
Wherein said solid oxide fuel cell comprises an internally reformed solid oxide fuel cell.
The method of claim 1,
Wherein said solid oxide fuel cell comprises a high temperature solid oxide fuel cell or a low temperature solid oxide fuel cell.
A method of manufacturing a solid oxide fuel cell, the method comprising: coating a surface of an anode having a fuel gas inlet and a fuel gas outlet on each side using a screen printing plate to have a density gradient with a catalyst.
10. The method of claim 9,
The screen printing plate making may include masking the entire screen original with a mask; Forming a pattern on the masked screen disc; And removing a mask of the formed pattern portion to form a patterning region to which a catalyst is coated.
And a ratio of the patterning area is changed from one side of the screen printing plate to the other.
The method of claim 10,
Wherein the coating step is performed by using the screen printing plate making the ratio of the patterning area higher or lower from the fuel gas inlet side to the fuel gas outlet side.
The method of claim 10,
The catalyst is a catalyst comprising Ni; A subcatalyst comprising Fe ₂ O ₃ , TiO ₂ , Cr ₂ O _3, or a combination thereof; Or a combination thereof.
The method of claim 12,
The coating with the cocatalyst is performed using the screen printing plate making the ratio of the patterning area increases from the fuel gas inlet side to the fuel gas outlet side. The method of claim 12,
The coating with the subcatalyst is performed using the screen printing plate making the ratio of the patterning area is lowered from the fuel gas inlet side to the fuel gas outlet side.
A first solid oxide fuel cell of any one of claims 1, 2 or 4;
A second solid oxide fuel cell formed in the same manner as the first solid oxide fuel cell; And
And a separator plate disposed between the first solid oxide fuel cell and the second solid oxide fuel cell, the separator including a cathode side gas passage and an anode side gas passage.

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