KR101307208B1 - Tubular solid oxide fuel cell with external current collection and preparation method thereof - Google Patents

Abstract

According to the present invention, since the solid oxide fuel cell can be easily connected in series, and since the current collector is not inserted into the solid oxide fuel cell, a cylindrical solid oxide fuel using an external current collecting method capable of realizing uniform and excellent performance due to constant fuel flow. It relates to a battery and a method of manufacturing the same.

Description

Cylindrical solid oxide fuel cell using external current collector and its manufacturing method {TUBULAR SOLID OXIDE FUEL CELL WITH EXTERNAL CURRENT COLLECTION AND PREPARATION METHOD THEREOF}

The present invention relates to a cylindrical solid oxide fuel cell using an external current collector and a method for manufacturing the same, and more particularly, to form a current collector on the outside of the cylindrical solid oxide fuel cell, and to facilitate the series connection. The present invention relates to a cylindrical solid oxide fuel cell having a current concentrating structure capable of realizing uniform and excellent performance since the fuel flow is not inserted, and a manufacturing method thereof.

The solid oxide fuel cell (Solid Oxide Fuel Cell: SOFC) is to generate electricity by an electrochemical reaction of a fuel (H _2, CO) and air (oxygen) at high temperatures of 600~1000 ℃ using a ceramic as the solid electrolyte As the fuel cell, there is an advantage that the power generation efficiency is the highest among existing power generation technologies and the economical efficiency is excellent.

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.

Flat SOFCs have high power density, high productivity, and thin electrolyte, but require gas sealing using a separate sealant, and due to the use of metal connecting materials at high temperatures, electrode efficiency is reduced due to chromium volatilization. However, it has a disadvantage of lacking reliability due to low resistance to thermal cycles. Moreover, since flat panel SOFCs are not only difficult to manufacture large-area cells but also easy to manufacture large-capacity stacks, solving these problems becomes a key to practical use.

Cylindrical SOFCs are evaluated as SOFC designs closest to commercialization because they do not require gas sealing, have excellent mechanical strength, and have been tested for reliability in various test items. However, the cylindrical SOFC has a disadvantage of high internal resistance and low power density because of a long current path. In addition, since the voltage output from the module, which is a collection of cells, is low, the power conversion loss during operation is large, and as a result, there is a weakness in efficiency.

As the length of the anode support increases, the reaction area can be increased to obtain high power. However, since the resistance increases in the longitudinal direction and the power density per unit area decreases, it is necessary to optimize in consideration of current collection characteristics.

European Patent No. 2188861 discloses a method of connecting an SOFC using a ring such as a current collector in order to facilitate connection between unit cells in a tubular fuel cell stack, but the current collector method disclosed in the European Patent has a uniform performance. But it can cause big performance drop.

In addition, as in the prior art, when the current is collected using a total current collection (TC) in the anode, the flow of fuel is not uniform by the current collector, and when applied to the stack, the current collector line comes out of the manifold, so that other units The series connection with the cathode of the battery is not easy.

In order to solve the above-mentioned problems, the present inventors can easily connect a series of external current collectors of the anode inlet / outlet part because the current collector lines come out when applied to the stack, and do not insert the current collector into the internal fuel flow. It has been found that this constant and uniform performance can be obtained, thus completing the present invention.

An object of the present invention is to facilitate the series connection of a solid oxide fuel cell, and since the current collector is not inserted into the solid oxide fuel cell has a constant current flow of the solid oxide fuel having a current focusing structure that can implement a uniform and excellent performance It is to provide a battery and a method of manufacturing the same.

In order to achieve the above object, the present invention is a cylindrical anode support; An electrolyte layer formed on an outer surface of the cylindrical anode support; And a cathode formed on the electrolyte layer, the cylindrical solid oxide fuel cell comprising: a silver-glass paste coating layer coated on the outer surface of the inlet and the outlet of the cylindrical anode support, the conductive metal mesh and the conductive wound on the coating layer; Provided is a cylindrical solid oxide fuel cell having a current collector structure comprising a metal-wire.

In addition, the present invention after extruding the anode support, drying and sintering; Coating and drying an electrolyte layer and a cathode on the anode support; Forming and coating a coating layer with silver-glass paste on outer surfaces of the inlet and outlet of the anode support; And winding the conductive metal-mesh on the coating layer, fixing the conductive metal-mesh by winding the conductive metal-wire on top thereof, and then applying a silver paste to provide a method of manufacturing a cylindrical solid oxide fuel cell.

The conductive metal may be Ag, Au, Pt, Ni, Co, W, Ti, Cu, Pd, Mn, Mo, Si and the like, the silver-glass paste coating layer is a silver powder, glass powder, binder and solvent It is formed using silver-glass paste prepared by mixing.

In one embodiment of the invention, it is preferable to form a coating layer with silver-glass paste on the outer surface of the inlet and outlet of the anode support and heat-treated at 700 ~ 800 ℃.

The present invention provides a cylindrical solid oxide fuel cell using an external current collector and a method for manufacturing the same, thereby facilitating series connection of the solid oxide fuel cell, and since the current is not inserted into the collector, the flow of fuel is constant. It is possible to realize uniform and excellent performance.

1 is a perspective view of a cylindrical solid oxide fuel cell using an external current collector according to the present invention.
Figure 2 is a photograph of the cylindrical solid oxide fuel cell prepared in Example 1, Comparative Example 1 and Comparative Example 2 of the present invention.
3 is a SEM photograph taken on the surface and the cross section of the external current collector of the cylindrical solid oxide fuel cell of Example 1 in Test Example 1 of the present invention.
4 is a graph showing the voltage and the output density measured for the cylindrical solid oxide fuel cells prepared in Example 1, Comparative Example 1 and Comparative Example 2 in Test Example 2 of the present invention.
5 is a graph showing the impedance measured for the cylindrical solid oxide fuel cell prepared in Example 1, Comparative Example 1 and Comparative Example 2 in Test Example 3 of the present invention.

Hereinafter, the present invention will be described in detail with reference to the drawings.

Cylindrical solid oxide fuel cell 100 using an external current collector according to the present invention is a general cylindrical including an electrolyte layer (130) and a cathode (120) formed on an anode support (anode support) It can be applied to a solid oxide fuel cell structure (see FIG. 1).

1, the present invention is characterized in that the external current collector 110 is formed in the structure of the general cylindrical solid oxide fuel cell, the external current collector 110 and the inlet of the cylindrical anode support; And a silver-glass paste coating layer coated on the outer surface of the outlet, a conductive metal mesh and a conductive metal wire wound on the coating layer.

In one embodiment of the present invention, the conductive metal may be Ag, Au, Pt, Ni, Co, W, Ti, Cu, Pd, Mn, Mo, Si and the like, but is not necessarily limited thereto.

The silver-glass paste coating layer uses a silver-glass paste having the same composition as that using an internal current collector of a conventional cylindrical anode support, and is, for example, a silver-made by mixing silver powder, glass powder, a binder, and a solvent. It is formed using glass paste.

Cylindrical solid oxide fuel cell 100 using an external current collector according to the present invention is manufactured by performing the following steps:

 Extruding the anode support, followed by drying and sintering; Coating and drying an electrolyte layer and a cathode on the anode support; Forming and coating a coating layer with silver-glass paste on outer surfaces of the inlet and outlet of the anode support; And winding the conductive metal-mesh on the coating layer, fixing the conductive metal-mesh by winding the conductive metal-wire on top thereof, and then applying a silver paste.

The cylindrical anode support may be a porous cylindrical anode support manufactured using nickel / yttria stabilized zirconia cermet.

In one embodiment of the present invention, the cylindrical anode support is a mixture of nickel oxide, yttria stabilized zirconia and a pore-forming agent ball milling and drying to prepare a compressed powder; Preparing a paste by mixing the compressed powder, an organic binder, a plasticizer, a lubricant, and distilled water; It can be prepared by extruding the paste into a cylindrical support using an extruder and drying and pre-sintering the cylindrical support.

Thereafter, the electrolyte layer 130 and the cathode 120 are sequentially formed on the upper surface of the cylindrical anode support.

In one embodiment of the present invention, the electrolyte layer 130 may be formed by mixing the yttria stabilized zirconia, the dispersant and the solvent by ball milling to coat the electrolyte slurry on the outer surface of the cylindrical anode support, the present invention Oxygen ion conductive electrolyte membranes known in the art can be used without limitation.

In one embodiment of the present invention, as the cathode film, a multilayered cathode film in which an LSM-YSZ layer, an LSM layer, and an LSCF layer are sequentially formed may be used, and thus, the electrode is activated and the polarization resistance is reduced.

Next, a coating layer is formed of silver-glass paste on the outer surfaces of the inlet and the outlet of the anode support and heat treated.

In one embodiment of the present invention, the silver-glass paste coating layer is a silver-glass paste prepared by mixing the silver powder, glass powder, a binder and a solvent on the outer surface of the inlet and outlet, and then 700 ~ 800 ℃ It is preferable to heat-treat with.

Finally, the conductive metal-mesh is wound around the coating layer, and the conductive metal-mesh is fixed by winding the conductive metal-wire on top thereof, and then a commercially available silver paste is applied to form a cylindrical solid oxide fuel cell using an external current collector. Manufacture.

Hereinafter, preferred embodiments and test examples of the present invention will be described in detail. 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, test examples, and drawings described in this specification are preferred embodiments of the present invention and do not represent all the technical ideas of the present invention, so that there are various equivalents and modifications that can be substituted at the time of the present application .

Example  One

(1) Preparation of unit cell

YSZ (8 mol% Y2O3 doped ZrO2, TZ8Y, 0.3 μm, Tosho, Japan) and NiO (Nickleous Oxide, 0.8 μm, JT. Baker, USA) were used to prepare anode powders used in solid oxide fuel cells. Cylindrical micro-SOFC anode support was prepared using a pore-forming agent of AC pore-forming agent (Activated Carbon, YP-50F, ˜20 μm, Kuraray Chemical Co., Japan) in microns. First, it was quantified to 40 vol% Ni / 8YSZ using NiO and YSZ in order to obtain a powder of uniform composition, mixed with a pore-forming agent of AC and wet milled in ethanol solution for 2 weeks, and then dried on a hot plate To prepare a powder for kneading. The sifted mixed powder was added for distilled water, an organic binder, a plasticizer, and a lubricant for extrusion to prepare an extrusion paste through kneading. The kneaded paste was produced by extrusion molding. In this case, the diameter of the molded body was prepared in consideration of the shrinkage ratio after sintering, a cylindrical molded body of 8.1 mm in diameter. The extruded cylindrical molded body was rolled and dried at a speed of 70 rpm in order not to damage the surface. After drying, the molded product was heat-treated at 350 ° C. for 0.5 hours at a heating rate of 0.58 ° C./minute for 5 hours, and then heated to 750 ° C. for 3 hours at a heating rate of 1.33 ° C./minute, and then calcined at 1100 ° C. at 1.33 ° C./minute. Pre-Sintering. The reason for the stepwise heat treatment at 350 ℃, 750 ℃ and 1100 ℃ during plastic sintering is to debind distilled water, polymer additives and pore formers. The sintered support was immersed in a fine anode functional layer having the same composition to enhance the catalytic role of Ni, and then heat-treated at 1000 ° C. for 3 hours in an air atmosphere at a temperature increase rate of 1.67 ° C./min. It was.

In order to form the electrolyte layer into a dense membrane, a vacuum slurry was coated with the highest zirconia-based ScSZ (10 mol% Scandia Stablized-Zirconia), and in the process, an external current collector was formed to form an external current collector at the inlet and the outlet. The part where the current collector is formed was masked to prevent the electrolyte from being coated. After heat treatment at 1000 ° C. for 3 hours in an air atmosphere at a temperature of 1.67 ° C./minute, GDC (Gdolia Doped Ceria) was vacuum-coated again, and then 1400 ° C. and 5 hours at an air temperature of 1.67 ° C./min. Sintered by heat treatment. The air electrode is to the redox reaction at the interface between the air electrode in reducing total polarization resistance LSCF by mixing the electrolyte and the air electrode _{((La 0 .6 Sr 0 .4} Co 0 .2 Fe 0 .8 O 3) / GDC After immersing the composite electrode twice, and then coating the LSCF once, the composite electrode was sintered by heating at 1150 ° C. for 3 hours at an air temperature of 1.67 ° C./min.

(2) external current Whole  formation

Ag-glass paste was coated on the outside of the masked inlet and outlet of the anode support by brush coating to coat the unit cell manufactured as described above, and dried at 90 ° C. It was coated on a commercial Ag-paste and then heat-treated at 700 ℃. Ag-mesh and Ag-wire were wound on the outer surface of the anode, and then Ag-wire was wound in the circumferential direction to fix Ag-mesh and collected evenly using Ag-paste.

(3) Air pole  Current collector

In the cathode current collecting method, the Ag-mesh was wound around the cathode and the Ag-wire was wound in the circumferential direction to fix the Ag-mesh. Then La _{0 .6} Sr _{0 .4} gave apply a Ni- paste CoO ₃ (LSCo) paste on the air electrode surface to reduce the contact resistance evenly using a brush coating method.

2 illustrates a cylindrical solid oxide fuel cell of the present invention manufactured as described above.

Comparative example  One

The same process as in Example 1 was performed except that the electrolyte was not coated by masking a portion of the inlet and the outlet to form an external current collector during the formation of the electrolyte layer, and then forming an external current collector on the masked portion. A cylindrical solid oxide fuel cell was manufactured, and the manufactured cylindrical solid oxide fuel cell is shown in FIG. 2.

Comparative example  2

After forming the electrolyte layer and coating the electrolyte without masking, Ni-Felt and Ni-Wire are metal-welded to the inside of the anode to collect the inside of the anode, and the Ni-paste is brushed using a brush coating method. After inserting and evenly applying current, the cathode was collected as in Example 1 to manufacture a cylindrical solid oxide fuel cell, and the prepared cylindrical solid oxide fuel cell is shown in FIG. 2.

Test Example  1: Observation of Microstructure of Cylindrical Solid Oxide Fuel Cell

The surface of the external current collector of the cylindrical solid oxide fuel cell manufactured in Example 1 was photographed with a scanning electron microscope (SEM) and is shown in FIG. The cross section of the external current collector of the battery was photographed with an electron scanning microscope and shown in FIG. 3 (b).

Referring to (a) of FIG. 3, it can be seen that fine holes exist on the surface of the external current collector, but grain growth of silver (Ag) is well achieved. In addition, referring to Figure 3 (b), it can be seen that the sintering is well connected and electrically connected between the external current collector and the anode functional layer, and the fracture surface of the external current collector is densely formed. This means that the outflow of fuel from the porous anode support can be blocked.

Test Example  2: Performance and Characterization of Cylindrical Solid Oxide Fuel Cells

In order to evaluate the performance and characteristics of the cylindrical solid oxide fuel cells prepared in Example 1, Comparative Example 1 and Comparative Example 2, a unit cell was installed in an electric furnace, and the temperature was increased at a rate of 1.5 to 2 ° C./minute, followed by performance evaluation. . Performance characteristics of the cylindrical solid oxide fuel cells manufactured in Example 1, Comparative Example 1 and Comparative Example 2 using an electric furnace (DP-500, Daegil Electrics) was flowed at 2 L / min to the cathode at 750 ℃, respectively In the fuel electrode, H ₂ was flowed at 150 cc / min, and the change in voltage and power density was measured while changing the electronic load, and the results are shown in FIG. 4.

Referring to Figure 4, the maximum power density of each of the cylindrical solid oxide fuel cells prepared in Example 1, Comparative Example 1 and Comparative Example 2 is 236 mW / cm ² , 56 mW / cm ² And 261 mW / cm ² . In the cylindrical solid oxide fuel cell manufactured in Comparative Example 2, current collection was performed in the entire unit cell, and the cylindrical solid oxide fuel cell prepared in Comparative Example 1 exhibited maximum resistance in the longitudinal direction of the unit cell. As it is rapidly increased, the performance is rapidly decreased. In the cylindrical solid oxide fuel cell manufactured in Example 1, the unit cell showed similar performance as that of Comparative Example 2, which can be seen that the same performance as the conventional internal current collector even if the external current collector.

Test Example  3: Impedance Analysis of Cylindrical Solid Oxide Fuel Cells

Nyquist plot showing the change of impedance value on real and imaginary axis by using alternating current impedance (SI1260, Solatron) for cylindrical solid oxide fuel cells manufactured in Example 1, Comparative Example 1 and Comparative Example 2 5 is shown.

Referring to FIG. 5, the magnitudes of the impedance curves representing the magnitude of the polarization resistance of the cylindrical solid oxide fuel cells prepared in Comparative Example 1 and Comparative Example 2 were similar. On the other hand, the magnitudes of the impedance curves of the cylindrical solid oxide fuel cell manufactured in Comparative Example 1 gradually increased. The magnitude of the impedance curve is the smallest in the cylindrical solid oxide fuel cells prepared in Example 1 and Comparative Example 2. Therefore, their polarization resistance value is the lowest. It can be observed that the polarization resistance of the cylindrical solid oxide fuel cell manufactured in Comparative Example 1 increases rapidly. It can be interpreted that the resistance component of the high frequency region has a greater influence on the increase in the polarization resistance than the resistance component of the low frequency region. The Ohmic resistance from the origin of the impedance spectrum to the start of the semicircle is greatly influenced by the electrode contact problem and the charge transfer resistance. Therefore, as shown in Example 1, Comparative Example 1, and Comparative Example 2, the difference in the polarization resistance values of the cylindrical solid oxide fuel cells manufactured by using three current collector methods is the largest in the charge transfer resistance in the longitudinal direction. You can conclude that you are affected.

Referring to Test Example 2 and Test Example 3, the cylindrical solid oxide fuel cells prepared in Example 1 and Comparative Example 2 showed about five times the performance of the cylindrical solid oxide fuel cells prepared in Comparative Example 1. The longitudinal resistance of the support is reduced to improve performance. From this, it can be seen that the cylindrical solid oxide fuel cell of the present invention can be easily implemented in series and excellent in performance by using an external current collector.

Description of the Related Art [0002]
100: cylindrical solid oxide fuel cell
110: external current collector
120: air electrode
130: electrolyte layer

Claims (7)

Cylindrical anode support; An electrolyte layer formed on an outer surface of the cylindrical anode support; And a cathode formed on the electrolyte layer, the cylindrical solid oxide fuel cell comprising: a silver-glass paste coating layer coated on the outer surface of the inlet and the outlet of the cylindrical anode support, the conductive metal mesh and the conductive wound on the coating layer; A cylindrical solid oxide fuel cell having a current collector comprising a metal-wire.
The method according to claim 1,
The conductive metal is cylindrical solid oxide, characterized in that any one or two or more materials selected from the group consisting of Ag, Au, Pt, Ni, Co, W, Ti, Cu, Pd, Mn, Mo and Si Fuel cell.
The method according to claim 1,
The silver-glass paste coating layer is a cylindrical solid oxide fuel cell, characterized in that formed by coating a silver-glass paste prepared by mixing a silver powder, glass powder, a binder and a solvent.
Extruding the anode support, drying and plasticizing the anode support;
Coating and drying an electrolyte layer and a cathode on the anode support;
Forming and coating a coating layer with silver-glass paste on outer surfaces of the inlet and outlet of the anode support; And
Winding the conductive metal-mesh on the coating layer, fixing the conductive metal-mesh by winding the conductive metal-wire on top thereof, and then applying a silver paste;
Cylindrical solid oxide fuel cell manufacturing method comprising a.
The method of claim 4,
Forming a coating layer with a silver-glass paste on the outer surface of the inlet and outlet of the anode support and the heat treatment at 700 ~ 800 ℃ characterized in that the manufacturing method of the cylindrical solid oxide fuel cell.
The method of claim 4,
The conductive metal-mesh and the conductive metal-wire are a method of manufacturing a cylindrical solid oxide fuel cell, characterized in that the silver-mesh and silver-wire, respectively.
The method of claim 4,
The coating layer is a method of manufacturing a cylindrical solid oxide fuel cell, characterized in that formed by coating a silver-glass paste prepared by mixing a silver powder, glass powder, a binder and a solvent.

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