KR20130019171A - Preparation method of anode support for tubular solid oxide fuel cell having high performance, anode support prepared therewith and tubular solid oxide fuel cell comprising the same - Google Patents

Abstract

PURPOSE: A manufacturing method of a fuel electrode support is provided to obtain a fuel electrode support with excellent porosity, electric conductivity, mechanical strength, and gas permeability. CONSTITUTION: A manufacturing method of a fuel electrode support comprises: a step of mixing an activated carbon or carbon black to a Ni/8YSZ cement and adding a solvent to the same to prepare a slurry and uniformizing the slurry by a ball-milling; a step of drying and powderizing the mixture; a step of adding a binder, plasticizer, lubricant, and distilled water, and milling the mixture to manufacture a paste; a step of extruding the paste to manufacture a fuel electrode support; and a step of heat-treating and pre-sintering the fuel electrode support.

Description

A method of manufacturing a cathode support for a cylindrical solid oxide fuel cell, which exhibits high performance, a cathode support for a solid oxide fuel cell manufactured using the same, and a cylindrical solid oxide fuel cell including the same. ANODE SUPPORT PREPARED THEREWITH AND TUBULAR SOLID OXIDE FUEL CELL COMPRISING THE SAME}

The present invention relates to a method of manufacturing a cathode support for a cylindrical solid oxide fuel cell exhibiting high performance, a cathode support for a solid oxide fuel cell manufactured using the same, and a cylindrical solid oxide fuel cell including the same, and more particularly, high porosity and electricity. A method of manufacturing a cathode support for a cylindrical solid oxide fuel cell capable of exhibiting conductivity, strength, and gas permeability, and a cylindrical solid oxide fuel cell including the anode support for a solid oxide fuel cell manufactured using the same.

Solid Oxide Fuel Cell (SOFC) produces electricity by electrochemical reaction of fuel (H ₂ , CO) and air (oxygen) at high temperature of 600 ~ 1000 ℃ using solid ceramic as electrolyte. As a fuel cell, there is an advantage in generating power generation efficiency and excellent economic efficiency among the existing power generation technology.

Since SOFC and electrolyte are in solid state, it can be manufactured in various types of cells such as flat plate and cylinder, and classified into anode support type, cathode support type, and electrolyte support type according to fuel cell support. do.

In general, a cathode support of a cylindrical SOFC is prepared by mixing a zirconia-based ceramic, a pore former, a binder, a plasticizer, a lubricating oil, and distilled water to prepare a paste. It is manufactured by.

The cylindrical SOFC described above is capable of high output, and in order to exhibit high starting speed and heat cycle resistance, it is required that the cylindrical porous anode support has high porosity, electrical conductivity, mechanical strength, and gas permeability.

Accordingly, the inventors have intensively studied a cylindrical SOFC showing excellent performance, and as a result, high porosity when the Ni / 8YSZ cermet, a pore forming agent, a binder, a plasticizer, a lubricating oil, and distilled water are mixed and manufactured at an optimum ratio, The present invention has been accomplished by knowing that an anode support for a cylindrical solid oxide fuel cell exhibiting electrical conductivity, mechanical strength and gas permeability can be manufactured.

SUMMARY OF THE INVENTION An object of the present invention is a method of manufacturing a cathode support for a cylindrical solid oxide fuel cell, which can exhibit high porosity, electrical conductivity, mechanical strength and gas permeability, and a cathode support for a solid oxide fuel cell manufactured using the same, and a cylindrical solid oxide comprising the same. To provide a fuel cell.

In order to achieve the above object, the present invention is a mixture of 3 to 10% by weight of activated carbon or carbon black to 90 to 97% by weight Ni / 8YSZ cermet, and then added to the solvent to make a slurry in the form of a ball mill to homogenize Step (step 1);

Drying the activated carbon or carbon black in the uniform Ni / 8YSZ cermet in a dryer and then pulverized (step 2);

Preparing a paste by kneading by adding 15 to 20 parts by weight of binder, 4 to 8 parts by weight of plasticizer, 2 to 6 parts by weight of lubricant, and 20 to 25 parts by weight of distilled water to the powdered mixture based on 100 parts by weight of the mixture (step 3);

Extruding the paste prepared in step 3 to prepare an anode support for a solid oxide fuel cell (step 4); And

It provides a method for producing a cathode support for a cylindrical solid oxide fuel cell comprising the step (step 5) of heat treating and pre-sintering the anode support prepared in step 4.

In one embodiment of the present invention, the Ni / 8YSZ cermet is preferably a mixture of Ni and 8YSZ at 40:60 vol%.

Activated carbon or carbon black mixed with Ni / 8YSZ cermet in the present invention is preferably prepared by mixing in a weight ratio of 90:10 to 97: 3 in terms of high porosity, electrical conductivity, strength and gas permeability of the anode support.

In one embodiment of the present invention, in step 1, ethanol is added as a solvent to a mixture of Ni / 8YSZ cermet and activated carbon or carbon black, and high-purity zirconia balls are mixed and ball milled to prepare a mixed powder of the anode support. .

Methyl cellulose or hydroxypropyl methyl cellulose is used as the binder added to the mixed powder of the anode support in step 3, and as the plasticizer, propylene carbonate, polyethylene glycol, and dibutyl phthalate are used. phthalate), and the lubricating oil may be stearic acid.

The present invention also provides an anode support manufactured according to the method of manufacturing an anode support for a cylindrical solid oxide fuel cell, and a cylindrical solid oxide fuel cell prepared by using the same.

The present invention provides a method of manufacturing a cathode support for a cylindrical solid oxide fuel cell, which exhibits high porosity, electrical conductivity, strength, and gas permeability, and provides a cathode support for a cylindrical solid oxide fuel cell manufactured according to the present invention, which enables high output, startup speed, and thermal cycle. It can be used to manufacture a cylindrical solid oxide fuel cell with increased resistance.

1 is a cathode support and a pore-forming agent prepared by mixing the cermet with activated carbon (AC), carbon black (CB), and PMMA 3, 5, 10 wt% in Test Example 1 of the present invention. It is a graph showing the measured porosity on the anode support manufactured without.
FIG. 2 is a fuel electrode prepared without using a cathode support and a pore-forming agent prepared by mixing the cermet with 5% by weight of activated carbon (AC), carbon black (CB) and PMMA as pore-forming agents in Test Example 1 of the present invention. SEM image taken on the surface of the support.
FIG. 3 is a photograph taken with an optical microscope of pores formed in an anode support manufactured using activated carbon (AC) and carbon black (CB) as pore-forming agents in Test Example 1 of the present invention.
4 is a SEM photograph taken on the surface of the anode support prepared using 3% by weight and 5% by weight of activated carbon (AC) and carbon black (CB) as a pore-forming agent in Test Example 1 of the present invention.
5 is a schematic diagram of a DC 4-terminal method for measuring the electrical conductivity of the anode support in Test Example 1 of the present invention.
FIG. 6 is a view illustrating an anode support prepared by mixing the cermet with 3 wt%, 5 wt%, and 10 wt% of activated carbon (AC), carbon black (CB), and PMMA as a pore-forming agent in Test Example 1 of the present invention; This is a graph showing the conductivity measured.
FIG. 7 is a schematic diagram illustrating measurement of the compressive strength of the anode support in Test Example 1 of the present invention. FIG.
FIG. 8 is without using an anode support and a pore-forming agent prepared using 3% by weight, 5% by weight and 10% by weight of activated carbon (AC) and carbon black (CB) as pore-forming agents in Test Example 1 of the present invention. It is a graph which shows the measurement of the rolling strength for the manufactured anode support.
9 is a schematic diagram of a measuring device for measuring the gas permeability of the anode support in Test Example 1 of the present invention.
10 is without using a cathode support and a pore-forming agent prepared using 3% by weight, 5% by weight and 10% by weight of activated carbon (AC) and carbon black (CB) as a pore-forming agent in Test Example 1 of the present invention. It is a graph which measured and measured the gas permeability with respect to the produced anode support.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The terms and words used in the present specification and claims should not be construed as limited to ordinary or dictionary meanings and should be construed in accordance with the technical meanings and concepts of the present invention.

The embodiments and drawings described in the present specification are preferred embodiments of the present invention and are not intended to represent all of the technical ideas of the present invention, so that various equivalents and modifications may be substituted for them at the time of application of the present invention.

A method of manufacturing the anode support for a cylindrical solid oxide fuel cell according to the present invention will be described in detail below.

First, 3 to 10% by weight of activated carbon or carbon black is mixed with 90% to 97% by weight of Ni / 8YSZ cermet, and then, a solvent is added thereto, a slurry is prepared, and ball milled to homogenize (step 1).

In the present invention, Ni / 8YSZ cermet is used as a raw material powder of the anode support, and the Ni / 8YSZ cermet may be a mixture of Ni and 8YSZ at 40:60 vol%.

Ni, Co, Ru, and Pt may be used as the electrode for the anode support for the solid oxide fuel cell, but Ni is the most suitable material in terms of cost and performance. However, Ni has a disadvantage of low resistance to sintering and grain growth. Ni / 8YSZ cermet is preferably used as the material of the anode support in order to maintain the porous structure and reduce the difference in coefficient of thermal expansion between the electrolyte, and the electrical conductivity of the anode support is determined by the content of Ni and the degree of connection. It is more preferable to use the mixture of 8YSZ and 40:60 vol% as the material of the anode support for excellent performance.

In step 1, the finely powdered NiO powder and 8YSZ powder are weighed to be 40:60 vol% as a raw material of the anode support and mixed, and then activated carbon or carbon black is added as a pore forming agent and a solvent is added thereto. Prepared in a slurry state and homogenized by ball milling.

More specifically, by mixing 3 ~ 10% by weight of activated carbon or carbon black to 90 ~ 97% by weight of Ni / 8YSZ cermet, and then add ethanol as a solvent and a high-purity zirconia ball is mixed by ball milling for 1 to 2 weeks It is prepared by homogenizing the mixed powder of the anode support.

In the preparation of the mixed powder of the anode support, activated carbon and carbon black are preferably mixed with Ni / 8YSZ cermet at 3 to 10% by weight.

When the activated carbon or carbon black is used in less than 3% by weight, the porosity of the anode support may be lowered. When the activated carbon or carbon black is used in excess of 10% by weight, the porosity is increased, but the strength may be decreased. have.

When activated carbon is used as a pore-forming agent in the process of manufacturing a cathode support for a solid oxide fuel cell, the porosity and gas permeability of the anode support may be improved, thereby improving the performance of the SOFC, but it has the disadvantage of lowering the electrical conductivity. When carbon black is used as a pore-forming agent in the process of manufacturing an anode support for a solid oxide fuel cell, the performance of the SOFC can be improved because the electrical conductivity of the anode support is increased, but porosity and gas permeability are lowered.

In the present invention, it was found through experiments that the use of activated carbon or carbon black as a pore-forming agent in the manufacturing process of a cathode support for a solid oxide fuel cell can exhibit excellent porosity, electrical conductivity, strength, and gas permeability of the anode support. (See Test Example 1 below).

Thereafter, the mixture of Ni / 8YSZ cermet and activated carbon or carbon black homogenized in step 1 is dried in a dryer (hot plate) and then pulverized (step 2).

The paste is prepared by kneading by adding 15 to 20 parts by weight of binder, 4 to 8 parts by weight of plasticizer, 2 to 6 parts by weight of lubricant, and 20 to 25 parts by weight of distilled water to the mixture powdered in step 2 based on 100 parts by weight of the mixture. (Step 3).

The binder, plasticizer, and lubricating oil may be used without limitation, those conventionally known in the art to which the present invention pertains. For example, the binder may be methyl cellulose, hydroxypropyl methyl cellulose. The plasticizer may be propylene carbonate, polyethyleneglycol, dibutyl phthalate, and the like, and stearic acid may be used as the lubricant.

The binder is preferably added in an amount of 15 to 20 parts by weight based on 100 parts by weight of the mixed powder of the powdered anode support, and when the binder is added in an amount of less than 15 parts by weight, the formability of the anode support is reduced and the pore formation rate is lowered. If the binder is added in excess of 20 parts by weight, a lot of pores are formed in the anode support, but the strength decreases and cracks may occur in the sintering process.

Preferably, the plasticizer is added in an amount of 4 to 8 parts by weight based on 100 parts by weight of the mixed powder of the powdered anode support, and when the plasticizer is added in an amount less than 4 parts by weight, the moldability decreases during extrusion, thereby deforming the extruded body. And cracks may occur, and when the plasticizer is added in excess of 8 parts by weight, the ductility of the extruded body may be excessively increased, such that warpage deformation of the extruded body may occur.

The lubricant is preferably added in an amount of 2 to 6 parts by weight based on 100 parts by weight of the mixed powder of the powdered anode support, and when the lubricant is added in an amount less than 2 parts by weight, the surface is peeled off due to an increase in friction between the extrusion mold and the extruded body. Problems may occur, and when the lubricant is added in excess of 6 parts by weight, surface fringes may occur due to the adhesive force between the extruded body and the mold.

Preferably, the distilled water is added in an amount of 20 to 25 parts by weight based on 100 parts by weight of the mixed powder of the powdered anode support. And, it may cause a problem that the extrusion of the anode support is not easy. In addition, when the distilled water is added in excess of 25 parts by weight, the paste adheres to the screw surface of the extruder when the anode support is extruded, so that extrusion may not be performed well, and cracks may occur in the sintered anode support.

Next, the paste prepared in step 3 is extruded to prepare a cathode support for a solid oxide fuel cell (step 4).

In the step 4, the paste is extruded into a conventional extruder to prepare a cathode support, and it is preferable to undergo refrigeration for a predetermined time so that the moisture of the paste is evenly distributed before extrusion.

Finally, the extruded anode support is heat treated and calcined (step 5).

Step 5 is a process of burning a component such as a binder, a pore-forming agent, a plasticizer, lubricating oil included in the extruded anode support.

Thereafter, the anode support for a cylindrical solid oxide fuel cell according to the present invention is manufactured by sintering the heat treated anode support at 1350 to 1450 ° C.

The anode support manufactured according to the above-described method for manufacturing a cathode support for a cylindrical solid oxide fuel cell has excellent porosity, electrical conductivity, strength, and gas permeability, and the cylindrical solid oxide fuel cell manufactured by using the anode support is capable of high output and start up. Speed and heat cycle resistance can be increased.

Test Example  One: Anode  Physical property and microstructure measurement test of support

A pore former was mixed in a cermet in which 1000 g of NiO powder (JT Baker) and 790.32 g of 8YSZ powder (Tosoh Co.) were mixed. Ethanol was added thereto, homogenized by wet ball milling using high purity zirconia balls, dried on a hot plate, and then ground using a grinder. A paste was prepared by kneading YB-131D 356 g and distilled water 440 g as a binder to a mixture of the prepared NiO / YSZ powder and activated carbon powder, and the resultant was refrigerated after refrigeration for 24 hours so as to distribute the moisture evenly. It was. The extruded support under each condition was reduced at 800 ° C. after sintering at 1400 ° C. for 5 hours. Activated carbon, carbon black, and PMMA as pore-forming agents were mixed with the cermet at 3, 5, and 10% by weight, respectively, to prepare a cathode support according to the above method, and to the method without adding a pore-forming agent as a reference. According to the present invention.

(One) Anode  Measurement of porosity of the support

The pore of the anode support prepared by mixing the cermet with the activated carbon (AC), carbon black (CB) and PMMA 3, 5, 10 wt% as the pore forming agent and the pore forming agent without using the pore forming agent. The figure was measured and the result is shown in FIG.

Referring to FIG. 1, a pore size of 30.73% of a cathode support specimen manufactured without adding a pore-forming agent was shown. This is due to the reduction process and the removal of the additives. The anode support specimens prepared using 3% by weight, 5% by weight, and 10% by weight of activated carbon exhibited porosities of 41.00%, 43.60%, and 47.10%, respectively, and 3% by weight, 5% by weight, and 10% by weight of carbon black. The anode support specimens fabricated using showed a porosity of 33.83%, 34.12% and 34.79%, respectively. In addition, the porosity of the anode support specimen prepared using 5 wt% PMMA was 36.63%. From this, when using activated carbon as a pore forming agent in the process of manufacturing the anode support, it can be seen that the pore forming effect is the greatest.

(2) Anode  Microstructure Measurement of Support

SEM image of the anode support prepared by mixing the cermet with 5% by weight of activated carbon (AC), carbon black (CB) and PMMA as the pore-forming agent and the surface of the anode support prepared without using the pore-forming agent were measured. 2 is a photomicrograph of the pores formed in the anode support manufactured using activated carbon (AC) and carbon black (CB) as a pore forming agent, respectively, FIGS. 3A and 3B. The SEM photographs of the anode support surfaces prepared using 3% by weight and 5% by weight of activated carbon (AC) and carbon black (CB) as pore-forming agents are shown in FIG. 4.

Referring to FIG. 2, the effect of pore formation on the anode support by adding the pore forming agent can be confirmed. Although the particle distribution and pore distribution of the anode support to which activated carbon and carbon black are added are not uniform, it can be seen that the anode support to which PMMA is added is distributed relatively uniformly. In the case of PMMA, primary particles are well dispersed, but it can be expected that primary particles of activated carbon and carbon black are aggregated. In order to manufacture a cathode support having a uniform microstructure, it is important to treat the aggregates of activated carbon and carbon black before mixing the powder of the anode support. The problem of agglomeration of primary particles is greater in carbon black than in activated carbon.

Referring to FIG. 3, inside the anode support to which carbon black is added, large pores due to aggregates of primary particles may be observed. Referring to FIG. 4, pores of the anode support may be increased by increasing the content of activated carbon and carbon black. It can be seen that the degree can be improved.

(3) Anode  Measurement of the electrical conductivity of the support

Fuel electrode prepared by mixing the cermet with 3% by weight, 5% by weight and 10% by weight of activated carbon (AC), carbon black (CB) and PMMA as pore-forming agents using the DC 4-terminal method shown in FIG. Electrical conductivity was measured for the support. Electrical conductivity was measured in the range of 650 ~ 850 ℃ applying a current of 100 mA in a reducing atmosphere and the results are shown in FIG.

Referring to FIG. 6, as the content of the pore-forming agent increases, the electrical conductivity of the anode support decreases. The decrease in electrical conductivity was due to the increase in porosity which inhibited the connection of Ni particles. Specimens added with 3% by weight of carbon black showed good conductivity of 1057 S / cm at 600 ° C.

(4) Anode  Mechanical strength measurement of the support

The breakdown strengths of anode support prepared using 3% by weight, 5% and 10% by weight of activated carbon (AC) and carbon black (CB) as pore-forming agents and anode support prepared without pore-forming agent were standardized. It was calculated by the JIS Z 2507 standard formula represented by the following Equation 1 using the crush strength measurement method shown in the crushing strength measurement schematic diagram shown in Figure 7, the results are shown in FIG.

[Equation 1]

In Equation 1, the compressive strength, the maximum load at break, the outer diameter of the specimen, the thickness of the ring, and the length of the specimen.

Referring to FIG. 8, the anode support specimen prepared without using the pore-forming agent exhibited a crushing strength of 123.77 MPa. In addition, the anode support specimens prepared using 3% by weight, 5% by weight and 10% by weight of activated carbon (AC) exhibited strengths of 81.02 MPa, 75.50 MPa, and 53.40 MPa, respectively, and 3% by weight of carbon black (CB) and 5%. The anode support specimens prepared using the wt% and 10 wt% exhibited strengths of 90.78 MPa, 85.64 MPa, and 73.00 MPa, respectively. Differences in the microstructure and porosity of the anode support fabricated using activated carbon and carbon black are considered to be important factors in mechanical strength. The anode support prepared using carbon black has many macropores, but exhibits low porosity and is made of smaller pores, indicating higher mechanical strength than the anode support prepared using activated carbon. Since the anode support used in the solid oxide fuel cell serves to support the unit cell in the construction of the unit cell, the anode support must have sufficient strength to withstand thermal shock or external shock.

(5) Anode  Gas Permeability Measurement of Support

Gas permeability of the anode support prepared using 3% by weight, 5% and 10% by weight of activated carbon (AC) and carbon black (CB) as the pore-forming agent and the anode support prepared without the pore-forming agent is shown in FIG. 9. As shown in the schematic diagram of the measuring device for measuring the gas permeability of the anode support as shown in Fig. 2, a constant flow rate of hydrogen was flowed to the anode support and the opposite side was sealed to measure the pressure difference generated when hydrogen gas penetrated the anode support. , Gas permeability was calculated using Darcy's law represented by the following equation (2). The results are shown in Fig.

&Quot; (2) "

In equation (2): flow rate, gas permeability, viscosity coefficient, differential pressure, support surface area, support thickness.

Referring to FIG. 10, an anode support manufactured using activated carbon having a high porosity and a large pore size exhibits higher gas permeability than an anode support using another pore-forming agent. In addition, it can be seen that the effect on the gas permeability according to the content is greater in the anode support manufactured using activated carbon than carbon black.

Claims (11)

90% to 97% by weight of Ni / 8YSZ cermet and 3 to 10% by weight of activated carbon or carbon black, followed by adding a solvent to the slurry to prepare a slurry and uniformly ball milling (step 1);
Drying the mixture of the homogenized Ni / 8YSZ cermet and activated carbon or carbon black in a dryer and then pulverizing the powder (step 2);
Preparing a paste by kneading by adding 15 to 20 parts by weight of binder, 4 to 8 parts by weight of plasticizer, 2 to 6 parts by weight of lubricant, and 20 to 25 parts by weight of distilled water to the powdered mixture based on 100 parts by weight of the mixture (step 3);
Extruding the paste prepared in step 3 to prepare an anode support for a solid oxide fuel cell (step 4); And
A method of manufacturing a cathode support for a cylindrical solid oxide fuel cell comprising the step (step 5) of heat treating and pre-sintering the anode support prepared in step 4.
The method according to claim 1,
The Ni / 8YSZ cermet is a method of manufacturing a cathode support for a cylindrical solid oxide fuel cell, characterized in that Ni and 8YSZ is mixed at 40:60 vol%.
The method according to claim 1,
The method of manufacturing a cathode support for a cylindrical solid oxide fuel cell, characterized in that prepared in step 1 by mixing 3 to 10% by weight of a mixture of activated carbon or carbon black to 90 ~ 97% by weight Ni / 8YSZ cermet.
The method according to claim 1,
The binder is a manufacturing method of a cathode support for a cylindrical solid oxide fuel cell, characterized in that the methyl cellulose or hydroxypropyl methyl cellulose.
The method according to claim 1,
And the plasticizer is selected from the group consisting of propylene carbonate, polyethyleneglycol, and dibutyl phthalate.
The method according to claim 1,
The lubricating oil is a method of manufacturing a cathode support for a cylindrical solid oxide fuel cell, characterized in that stearic acid (Stearic Acid).
The method according to claim 1,
Preparation of a cylindrical solid oxide fuel cell anode support for a cylindrical solid oxide fuel cell, characterized in that in step 1 by adding ethanol as a solvent to the Ni / 8YSZ cermet and a mixture of activated carbon and carbon black and mixing high purity zirconia balls for 1 to 2 weeks Way.
The method according to claim 1,
The method of manufacturing a cylindrical solid oxide fuel cell anode support for the solid oxide fuel cell, characterized in that the refrigerated storage so that the moisture is evenly distributed before extruding the anode support for solid oxide fuel cell.
The method according to claim 9,
A method for producing a cylindrical solid oxide fuel cell anode support, characterized in that the sintered anode support for solid oxide fuel cells is sintered at 1350 to 1450 ° C.
A cathode support for a cylindrical solid oxide fuel cell manufactured according to any one of claims 1 to 9.
A cylindrical solid oxide fuel cell comprising the anode support for a cylindrical solid oxide fuel cell of claim 10.

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