KR102001592B1 - Anode supporter for solid oxide fuel cell, method of fabricating the same, and solid oxide fuel cell stack including the same - Google Patents

Abstract

Yttrium stabilized zirconia powder; Nano nickel powders; And zirconium tungsten phosphate powder, a method for producing the anode support, and a solid oxide fuel cell stack including the cathode support.

Description

[0001] The present invention relates to an anode support for a solid oxide fuel cell, a method for manufacturing the same, and a solid oxide fuel cell stack including the anode support, a method for manufacturing the solid oxide fuel cell stack,

An anode support for a solid oxide fuel cell, a method of manufacturing the anode support, and a solid oxide fuel cell stack including the same.

Recently, there is an urgent need for development of environmentally friendly new energy sources due to the depletion of energy resources and interest in environmental problems. For this reason, the development of fuel cells is attracting much attention by many researchers in various countries. Fuel cells are energy conversion devices that convert chemical energy directly into electrical energy. The main fuel uses hydrogen. However, these hydrogen are ideal fuels, but their production costs are high and they are limited to stable storage. As a result, studies on solid oxide fuel cells (SOFCs) operating at high temperatures have been actively conducted so that hydrocarbons as well as hydrogen can be used as fuel.

The stack configuration of solid oxide fuel cells consists largely of a unit cell, a separation plate for electrical passage and stacking, and a gas-tight seal. The dual unit cell is composed of a negative electrode (also referred to as an 'anode'), an electrolyte and an anode (also referred to as a 'cathode'). In the SOFC, which generates electricity through the movement of oxygen ions, oxygen ions move from the anode to the cathode through the difference in oxygen partial pressure between the cathode and the anode. In order to achieve chemical equilibrium at this time, And the current is obtained.

At present, nickel (Ni) -yttrium stabilized zirconia (YSZ) cermet is mainly used as an anode material of a solid oxide fuel cell. Ni-YSZ cermets are low in raw material cost, stable under high temperature reducing atmosphere, and have sufficient electrical conductivity and reactivity at the operating temperature of the SOFC.

This anode material is manufactured by a method of preparing a substrate by sintering at 1400 ° C. or higher using nickel oxide and YSZ powder, but it is difficult to control the size due to severe shrinkage behavior during the sintering process, and further processing is required. There is a problem that warpage occurs and the temperature rise and cooling time must be lengthened.

One embodiment is to provide a negative electrode support for a solid oxide fuel cell having excellent performance and long-term reliability by preventing cracking and floating between the negative electrode support and the electrolyte during operation.

Another embodiment is to provide a method for manufacturing the cathode support for the solid oxide fuel cell.

Another embodiment is to provide a solid oxide fuel cell stack including the cathode support for the solid oxide fuel cell.

One embodiment is a yttrium stabilized zirconia powder; Nano nickel powders; And a zirconium tungstate phosphate powder.

The negative electrode support comprises 35 to 60 wt% of the yttrium stabilized zirconia powder; 35 to 60 wt% of the nano-nickel powder; And 0.1 to 5% by weight of the zirconium tungstate phosphate powder.

The yttrium stabilized zirconia powder and the nano-nickel powder may be contained in a weight ratio of 1: 3 to 3: 1.

The nano-nickel powder may have an average particle diameter (D50) of 10 to 100 nm.

The zirconium tungstate phosphate powder may have an average particle diameter (D50) of 5 to 20 mu m.

The negative electrode support may further include a dispersant, a binder, or a combination thereof, and the dispersant and the binder may be of different kinds. When the negative electrode support includes the dispersant and the binder, the negative electrode support may include 0.5 to 2% by weight of the dispersant and 0.5 to 3% by weight of the binder.

Another embodiment provides a method of preparing a slurry comprising mixing a mixture comprising a yttrium stabilized zirconia powder, a nano-nickel powder, and a zirconium tungstophosphate powder with a solvent; Drying the slurry by a spray drying method to prepare spherical fine particles; And a step of press molding the spherical fine particles to produce a molded body.

The mixture may comprise 35 to 60 wt.% Of the yttrium stabilized zirconia powder, 35 to 60 wt.% Of the nano nickel powder, and 0.1 to 5 wt.% Of the zirconium tungstophosphate powder.

The mixture and the solvent may be mixed in a weight ratio of 1: 2 to 2: 1.

The mixture may further comprise a dispersant, a binder or a combination thereof, and the dispersant and the binder may be of different kinds. When the mixture comprises the dispersant and the binder, the mixture may comprise from 0.5 to 2% by weight of the dispersant and from 0.5 to 3% by weight of the binder.

The mixing can be performed by a wet milling process, which may include a basket milling process, a ball milling process, or a combination thereof.

The spherical fine particles may have an average particle diameter (D50) of 10 to 100 mu m.

And sintering the molded body to produce a sintered body, and the sintering may be performed at a temperature of 800 to 900 ° C.

Another embodiment includes a plurality of unit cells including a cathode, an anode, and an electrolyte; A separation plate disposed between the plurality of unit cells; And a seal portion sealing both ends of the plurality of unit cells and the separator plate, wherein the cathode includes the cathode support.

The details of other embodiments are included in the detailed description below.

It is possible to prevent cracks and floating between the anode support and the electrolyte during operation, thereby realizing a solid oxide fuel cell having excellent performance and long-term reliability.

1 is a schematic diagram illustrating 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.

The anode support for a solid oxide fuel cell according to an embodiment may include a yttrium stabilized zirconia (YSZ) powder, a nano nickel (Ni) powder, and a zirconium tungsten phosphate powder.

The yttrium stabilized zirconia powder may be contained in an amount of 35 to 60% by weight, specifically 45 to 55% by weight based on the total weight of the cathode support. When the yttrium stabilized zirconia powder is contained in the above range, the conductivity of oxygen ions is excellent.

The nano-nickel powder may have an average particle diameter (D50) of 10 to 100 nm, specifically 30 to 100 nm. When the nano-nickel powder has an average particle diameter within the above-mentioned range, the specific surface area increases to sufficiently form an oxide layer and have excellent dispersibility. In this case, D50 means a particle diameter corresponding to a cumulative volume of 50 vol% in the particle size distribution.

The nano-nickel powder may be contained in an amount of 35 to 60% by weight, particularly 45 to 55% by weight based on the total weight of the cathode support. When the nano-nickel powder is contained within the above range, it is excellent in electrical conductivity and volume expansion and cracking can be prevented due to proper oxidation.

The yttrium stabilized zirconia powder and the nano-nickel powder may be contained in a weight ratio of 1: 3 to 3: 1, and more specifically, in a weight ratio of 1: 2 to 2: 1. When the yttrium-stabilized zirconia powder and the nano-nickel powder are contained in the weight ratio within the above range, it is possible to simultaneously obtain oxygen ion conductivity by the yttrium-stabilized zirconia, which is a factor required for operating the fuel cell, and electric conductivity by the nano- .

The zirconium tungstophosphate powder may be, for example, a compound represented by the following general formula (1).

[Chemical Formula 1]

Zr ₂ WP ₂ O ₁₂

The zirconium tungstate phosphate powder may have an average particle diameter (D50) of 5 to 20 mu m, specifically, 7 to 15 mu m. When the zirconium tungstate phosphate powder has an average particle size within the above range, the effect of reducing the thermal expansion coefficient is excellent, and the thermal expansion coefficient of Ni-YSZ can be reduced even with a small amount. This makes it possible to improve thermal matching with yttrium stabilized zirconia, which is an electrolyte layer, without impairing the characteristics of Ni-YSZ.

The zirconium tungstate phosphate powder may be contained in an amount of 0.1 to 5% by weight, more specifically 0.5 to 3% by weight based on the total weight of the negative electrode support. When the zirconium tungstophosphate powder is included within the above range, the thermal expansion coefficient can be reduced without deteriorating the Ni-YSZ characteristics, thereby increasing the thermal matching with the electrolyte layer.

The negative electrode support may further include a dispersant, a binder, or a combination thereof. The dispersant and the binder may be of different kinds.

Specifically, the dispersing agent is selected from the group consisting of tetrasodium pyrophosphate, sodium polyacrylate, ammonium polyacrylate, citrate, sodium succinate, sodium tartrate, sodium polysulfonate, ammonium Citrate, or a combination thereof.

The binder may be selected from the group consisting of polyvinyl alcohol, polyvinyl butyral, polymethyl methacrylate, polyethylene glycol, paraffin, wax emulsion, microcrystalline wax, methylcellulose, sodium carboxymethylcellulose or a combination thereof.

The negative electrode support may include both the dispersant and the binder.

At this time, the dispersant may be included in an amount of 0.5 to 2% by weight, specifically 0.8 to 1.5% by weight based on the total weight of the anode support. When the dispersant is contained within the above range, the dispersibility of the yttrium stabilized zirconia powder, the nano-nickel powder and the zirconium tungstophosphate powder is excellent, and organic matter does not remain in the sintering process during the production of the cathode support, .

The binder may be included in an amount of 0.5 to 3% by weight, specifically 1 to 2% by weight based on the total weight of the negative electrode support. When the binder is contained within the above range, a solid molded body can be obtained when the cathode support is manufactured, and defects can be prevented in manufacturing the substrate because the organic matter does not remain in the sintering.

The cathode support described above can be produced by the following method.

Mixing the mixture containing the yttrium stabilized zirconia powder, the nano-nickel powder and the zirconium tungstophosphate powder with a solvent to prepare a slurry; Drying the slurry by a spray drying method to prepare spherical fine particles; And a step of press molding the spherical fine particles to produce a molded article.

The mixture may further comprise the dispersant, the binder or a combination thereof.

The mixing amount of each component in the mixture may be the same as the content range of the components constituting the negative electrode support described above.

The mixture and the solvent may be mixed in a weight ratio of 1: 2 to 2: 1, specifically 1: 1.5 to 1.5: 1. When mixing is carried out within the above-mentioned weight ratio range, the viscosity of the slurry is appropriate and spray drying can be carried out, thereby obtaining spherical fine particles of uniform size.

The solvent may be pure water.

The mixing of the mixture with the solvent may be carried out by a wet milling process. Examples of the wet milling process include a basket milling process, a ball milling process, or a combination thereof. When the wet milling process is performed, a uniformly dispersed slurry can be produced.

The spray drying can be performed by adjusting the rotation speed of the atomizing nozzle to 5,000 to 20,000 rpm. When adjusted to the above range, spherical fine particles having an average particle diameter (D50) of 10 to 100 mu m can be produced.

Spherical fine particles of uniform size can be produced through spray drying to obtain a sintered body having a high filling density and no warping and shrinkage due to uniform filling during the production of a molded body, can do.

The spherical fine particles may have an average particle diameter (D50) of 10 to 100 mu m, and more specifically, an average particle diameter (D50) of 30 to 70 mu m. When the spherical fine particles have an average particle diameter within the above range, it is possible to fill evenly at the time of the production of a molded body, thereby preventing warping and shrinkage during sintering, and a rigid molded body can be produced.

The spherical fine particles may be uniformly filled in a molding mold and then subjected to pressure molding to produce the molded body. The formed body may be in the form of a plate.

A step of pressing the spherical fine particles to produce a molded body, and then sintering the molded body to manufacture a sintered body. It is possible to blow away any organic matter remaining in the molded body during sintering,

The sintering may be carried out at a temperature of 800 to 900 ° C, and more specifically, at a temperature of 850 to 900 ° C. When sintering is performed within the above-mentioned temperature range, distortion and shrinkage do not occur, and a large-area cathode support can be obtained.

 The thus prepared anode support can be used in a solid oxide fuel cell. Specifically, the solid oxide fuel cell stack will be described with reference to the drawings.

1 is a schematic diagram illustrating the structure of a solid oxide fuel cell stack according to one embodiment. FIG. 1 is a view showing an example of a solid oxide fuel cell stack in which two unit cells are stacked to form a stack structure, but the present invention is not limited thereto.

1, a solid oxide fuel cell stack 10 according to an embodiment includes a plurality of unit cells including an anode 12, a cathode 14, and an electrolyte 16, And a sealing portion 18 sealed at both ends of the plurality of unit cells and the separating plate.

The cathode 14 may include the cathode support described above. The unit cell can be manufactured by coating an anode on a cathode support manufactured as described above, and then coating an anode with the electrolyte.

The sealing portion 18 can suppress the leakage of the gas generated in the anode 12 and the cathode 14.

Hereinafter, preferred embodiments and comparative examples of the present invention will be described. However, the following examples are only the preferred embodiments of the present invention, and the present invention is not limited by the following examples.

Example  One

985 g of yttrium stabilized zirconia powder, 985 g of nano-nickel powder having an average particle diameter of 30 nm, 10 g of zirconium tungstophosphate powder, 10 g of tetrasodium pyrophosphate as a dispersing agent, polyvinyl alcohol having a weight average molecular weight of 5,000 g / And 2000 g of pure water were mixed for 12 hours using a basket milling process to prepare a slurry.

The prepared slurry was dried using a spray drier and spherical fine particles having an average particle size (D50) of 30 mu m were prepared by controlling the rotation speed of the atomizing nozzle at 12,000 rpm.

The spherical fine particles thus prepared were filled in a 100 x 100 mm square mold and subjected to pressure molding at a pressure of 1000 kg / cm 2 to prepare a molded body in the form of a plate.

The formed body was heated to 400 ° C at a rate of 5 ° C / min and held for 1 hour to blow up the dispersant and the binder. The temperature was raised to 900 ° C at 2 ° C / min and maintained for 2 hours. min to prepare an anode support.

Example  2

An anode support was prepared in the same manner as in Example 1 except that 980 g of the yttrium stabilized zirconia powder, 980 g of the nano-nickel powder having an average particle diameter of 30 nm, and 20 g of the zirconium tungsten phosphate powder were used in Example 1.

Example  3

An anode support was prepared in the same manner as in Example 1, except that 975 g of the yttrium stabilized zirconia powder, 975 g of the nano-nickel powder having an average particle diameter of 30 nm, and 30 g of the zirconium tungsten phosphate powder were used in Example 1.

Example  4

An anode support was prepared in the same manner as in Example 1, except that 970 g of the yttrium stabilized zirconia powder, 970 g of the nano-nickel powder having an average particle diameter of 30 nm, and 40 g of the zirconium tungsten phosphate powder were used in Example 1.

Comparative Example  One

990 g of yttrium stabilized zirconia powder, 990 g of a nano-nickel powder having an average particle diameter of 30 nm, 10 g of tetrasodium pyrophosphate as a dispersant, 10 g of polyvinyl alcohol having a weight average molecular weight of 5,000 g / mol as a binder and 2000 g of pure water, milling) process for 12 hours to prepare a slurry. The procedure of Example 1 was repeated to prepare an anode support.

Evaluation 1: Measurement of thermal expansion coefficient

The negative electrode support prepared in Examples 1 to 4 and Comparative Example 1 was subjected to TMA (thermomechanical analysis) to raise the temperature from room temperature to 700 占 폚, and the thermal expansion coefficient was measured. The results are shown in Table 1 below.

The thermal expansion coefficient of yttrium stabilized zirconia (YSZ), which is an electrolytic material, was also measured, and the results are shown in Table 1 below.

Evaluation 2: Electrical conductivity measurement

The cathode support prepared in Examples 1 to 4 and Comparative Example 1 was reduced and the electrical conductivity was measured using a low resistance meter. The results are shown in Table 1 below.

Evaluation 3: crack  Measurement of occurrence

The cathode support prepared in Examples 1 to 4 and Comparative Example 1 was coated with an electrolyte layer using a plasma spraying method. The cathode was heated up to 700 ° C at room temperature and then cooled to analyze the cathode support and the electrolyte interface. Are shown in Table 1 below.

Coefficient of thermal expansion
(x10 < ^-7 > / DEG C) Electrical conductivity
(S / m) Crack occurrence Example 1 131 538 radish Example 2 126 535 radish Example 3 113 530 radish Example 4 106 531 radish Comparative Example 1 143 536 U Electrolyte (YSZ) 110 to 120 - -

It can be seen from Table 1 that the negative electrode supports of Examples 1 to 4 according to one embodiment did not crack even at a high temperature after coating the electrolyte layer as compared with Comparative Example 1. As a result, it can be seen that the performance can be maintained excellent during operation and long-term reliability can be ensured.

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, And it goes without saying that the invention belongs to the scope of the invention.

10: Solid oxide fuel cell stack
12: anode
14: cathode
16: electrolyte
18:
20: separation plate

Claims (18)

Yttrium stabilized zirconia powder;
Nano nickel powders; And
Zirconium tungsten phosphate powder
And a cathode support for a solid oxide fuel cell.
The method according to claim 1,
The negative electrode support
35 to 60% by weight of the yttrium stabilized zirconia powder;
35 to 60 wt% of the nano-nickel powder; And
0.1 to 5% by weight of the zirconium tungsten phosphate powder,
And a cathode support for a solid oxide fuel cell.
The method according to claim 1,
Wherein the yttrium stabilized zirconia powder and the nano-nickel powder are contained in a weight ratio of 1: 3 to 3: 1.
The method according to claim 1,
Wherein the nano-nickel powder has an average particle diameter (D50) of 10 to 100 nm.
The method according to claim 1,
Wherein the zirconium tungstate phosphate powder has an average particle diameter (D50) of 5 to 20 占 퐉.
The method according to claim 1,
The cathode support further comprises a dispersant, a binder or a combination thereof,
Wherein the dispersing agent and the binder are different kinds of negative electrode supports for a solid oxide fuel cell.
The method according to claim 6,
When the negative electrode support includes the dispersant and the binder,
Wherein the negative electrode support comprises 0.5 to 2% by weight of the dispersant and 0.5 to 3% by weight of the binder.
Preparing a slurry by mixing a solvent including a yttrium stabilized zirconia powder, a nano-nickel powder, and a zirconium tungstate phosphate powder with a solvent;
Drying the slurry by a spray drying method to prepare spherical fine particles; And
A step of press molding the spherical fine particles to produce a molded article
Wherein the solid oxide fuel cell comprises a cathode.
9. The method of claim 8,
The mixture
35 to 60% by weight of the yttrium stabilized zirconia powder,
35 to 60 wt% of the nano-nickel powder, and
0.1 to 5% by weight of the zirconium tungsten phosphate powder,
Wherein the solid oxide fuel cell comprises a cathode.
9. The method of claim 8,
Wherein the mixture and the solvent are mixed at a weight ratio of 1: 2 to 2: 1.
9. The method of claim 8,
The mixture further comprises a dispersant, a binder or a combination thereof,
Wherein the dispersant and the binder are different kinds.
12. The method of claim 11,
When the mixture includes the dispersant and the binder,
Wherein the mixture comprises 0.5 to 2% by weight of the dispersant and 0.5 to 3% by weight of the binder.
9. The method of claim 8,
Wherein the mixing is performed by a wet milling process.
14. The method of claim 13,
Wherein the wet milling process comprises a basket milling process, a ball milling process, or a combination thereof.
9. The method of claim 8,
Wherein the spherical fine particles have an average particle diameter (D50) of 10 to 100 占 퐉.
9. The method of claim 8,
And sintering the molded body to produce a sintered body
Wherein the solid oxide fuel cell further comprises a cathode.
17. The method of claim 16,
Wherein the sintering is performed at a temperature of 800 to 900 캜.
A plurality of unit cells including a cathode, an anode, and an electrolyte;
A separation plate disposed between the plurality of unit cells; And
Wherein the plurality of unit cells and the sealing plate
Lt; / RTI >
Wherein the cathode comprises the anode support of any one of claims 1 to 7.

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