KR101788553B1 - The Fabrication Method for Eletrode Device Comprising Anode Supporter and Electrolyte for Anode-supported SOFC by Using Sintering Additive and Co-firing - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a method of manufacturing an electrode element including an anode support and an electrolyte for anode-supported ceramic fuel cells using a sintering additive and a simultaneous sintering technique, A manufacturing method includes: a step of adding and sintering a sintering additive to a cathode support, an electrolyte, or both, and a cathode support including an ABO ₃ -based proton conductive ceramic of Formula 1 and a cathode . The formula is _{Ba (Zr 1 -xy Y x M} y) O 3-δ, where, M is at least one selected from the transition metals, the group consisting of Cu and Zn, x is 0 <x≤0.2, y 0 < y? 0.1 and? Is 0 &lt;?&Lt; 0.3.
The sintering may be simultaneous sintering of the cathode support and the electrolyte, the sintering additive may be ZnO or CuO, the cathode support may be formed by a liquid phase condensation method, and the electrolyte may be formed by a screen printing method.

Description

FIELD OF THE INVENTION [0001] The present invention relates to a cathode support for an anode-supported ceramic fuel cell using a sintering additive and a co-sintering method, and a method for manufacturing an electrode element including an electrolyte }

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a cathode support for an anode-supported ceramic fuel cell and an electrode assembly including the anode, and more particularly, to a cathode support for an anode support type ceramic fuel cell and an electrolyte using the sintering additive and the co- To a method of manufacturing an electrode element.

The fuel cell is an electric power generation system that uses an electrochemical reaction between an oxidizer and a fuel. Since the chemical energy of the fuel is not converted into heat and mechanical energy, the power generation efficiency is high and the environment preservation is excellent.

Fuel cells can be classified into phosphoric acid fuel cells (PAFC), polymer electrolyte fuel cells (PEMFC), molten carbonate fuel cells (MCFC), and solid oxide fuel cells (SOFC) depending on the electrolyte used. These fuel cells have operating ranges of about 80 ° C for the PEMFC, about 200 ° C for the PAFC, about 650 ° C for the MCFC, and about 800 ° C for the solid oxide fuel cell. Of these, SOFCs, which consist of ceramic and metal solids, are the most efficient, and have a variety of fuel choices and use of waste heat. They can be used for domestic fuel cells of 1-5 KW and gas turbines of 200 KW or higher And can be applied to cogeneration power generation.

Oxide-ion conductive ceramics such as Yttria Stabilized Zirconia (YSZ) doped with yttria (Y ₂ O ₃ ) as an electrolyte are mainly used in the solid oxide fuel cell, and in recent years, BACKGROUND ART [0002] Fuel cells using hydrogen-ion conductive ceramics which improve the durability of batteries as an electrolyte have attracted attention. The solid oxide fuel cell unit cell is classified into an electrolyte supporting type and an electrode supporting type according to a structural support. An electrode supporting type SOFC capable of minimizing the thickness of the electrolyte, among which an anode supporting type SOFC having a fuel electrode as a support, exhibits the highest performance.

The anode-supported type single cell has a structure in which an anode functional layer, an electrolyte layer, and a cathode layer are sequentially formed on a fuel electrode substrate. When the thermo-mechanical matching between the constituent components of the anode electrode-supported type single cell having such a multi-layered structure is different, the constituent components are broken or the components are separated from each other.

The anode-supported type single cell has a structure in which an anode functional layer, an electrolyte layer, and a cathode layer are sequentially formed on a fuel electrode substrate. At this time, the electrode of the unit cell must have a porous structure and the electrolyte must have a dense structure. Such a multi-layered anode-supported type single cell is liable to break down constituents or to cause interlayer separation when the thermomechanical compatibility between the constituents is different. Interfacial defects such as peeling and cracks occurring between the constituent layers increase the resistance of the unit cells and not only dramatically deteriorate the performance but also have a resistance to thermal stress which is remarkably weak. Such interfacial defects are caused by differences in the sintering shrinkage ratio between the constituent layers or by the difference in thermal expansion coefficient, and when the interfacial strength is weak, the defect size is increased to lower the production yield, The life of the single cell is remarkably reduced. Therefore, it is essential to control the sintering shrinkage ratio between the components in order to maintain the optimum structure for each component and to manufacture the unit cell without the multi-layer structure layer.

In order to fabricate a multilayer ceramic laminate, interlayer bonding is induced through heat treatment every layer as necessary. As the number of the heat treatment processes increases, the process cost and the process time are greatly damaged. Therefore, a simultaneous sintering process is required to minimize the number of heat treatment processes in order to establish low-cost, high-efficiency process conditions. Conventional sintering techniques are generally sintered simultaneously through complicated paths such as controlling the powder size and the composition ratio of the constituents. Particularly, in the case of a cathode supported SOFC, a very complicated design is required for the constituents because the support leads the overall sintering shrinkage ratio. In general, the anode support is composed of a composite of NiO or the like acting as a cathode and an electrolyte component (YSZ, BZY, etc.) having an oxygen ion conductor or hydrogen ion conductivity. In this case, since the sintering degree of the negative electrode component is generally higher than that of the electrolyte component, the mixing ratio between the two components is very important in order to obtain a dense electrolyte layer on the support through the simultaneous sintering process. In addition, since the cathode support has a porous structure in order to serve as an electrode, a pore-forming agent is generally added. It is also necessary to grasp the influence of the pore-forming agent on the shrinkage of the substrate. However, as in the case of the prior art, it becomes more and more difficult to design the simultaneous sintering process as the complexity of the powder size and composition of the components constituting the cathode support becomes complicated, so that the technique of controlling the shrinkage ratio between the anode support and the electrolyte by a simpler method Is required.

It is an object of the present invention to provide a solid oxide fuel cell capable of suppressing structural defects of each constituent layer of a solid oxide fuel cell and detachment or interfacial defects between constituent layers occurring in the manufacturing process and in particular to produce an electrolyte layer having a thin and dense structure without defects, Maximizing the mechanical properties as well as the electrochemical properties.

More specifically, it is an object of the present invention to develop a co-sintering process technology so as to make a dense thin-film electrolyte on a fuel electrode support which is a supporting substrate of a unit cell, without defect, in an anode-supported solid oxide fuel cell.

Another object of the present invention is to provide a method for manufacturing a unit cell more economically through a simultaneous sintering process in a fuel electrode supporting solid oxide fuel cell.

A method of manufacturing a fuel cell cathode element comprising a cathode support and an electrolyte according to the present invention comprises the steps of adding and sintering a sintering additive to an anode support, an electrolyte, or both, wherein the composition has an ABO ₃ -based hydrogen ion conductivity A method for producing a fuel cell cathode element comprising a cathode support comprising a ceramic and an electrolyte.

The formula is _{Ba (Zr 1 -x- y Y x} M y) O 3-δ, where, M is at least one selected from the transition metals, the group consisting of Cu and Zn, x is 0 <x≤0.2 , y is 0 < y? 0.1, and? is 0 <

The sintering may be simultaneous sintering of the cathode support and the electrolyte, the sintering additive may be ZnO or CuO, the cathode support may be formed by a liquid phase condensation method, and the electrolyte may be formed by a screen printing method.

According to the present invention, a large-area solid oxide fuel cell can be economically manufactured without defects by adjusting the shrinkage ratio and sintering degree of the electrolyte. Particularly, it is possible to improve the sintering degree by controlling the composition of the electrolyte through the additive, minimize the sintering effect on the electrolyte layer through simultaneous sintering and ensure a sufficient shrinkage ratio, thereby causing defects in the electrolyte layer, And the interfacial strength can be increased.

FIG. 1 is a graph showing the results of a comparison between BaZr _{0 .85} Y _{0 .15} O ₃ with 15 mol% of Y added with sintering additive and BaZr _{0 .81} Zn ₀ with 15 mol% Y added with sintering additive ZnO and CuO _.04 Y _{0 .15} O _{3 -δ} and BaZr _0.84 Cu _0.01 Y _0.15 O is a graph showing the Dilatometer metric analysis of the _3-δ.
FIG. 2 is a microstructure SEM photograph of BaZr _{0 .81} Zn _{0 .04} Y _{0 .15} O _{3 -δ} with 15 mol% of Y added with sintering additive ZnO.
Fig. 3 is a microstructure SEM photograph of BaZr _{0 .84} Cu _{0 .01} Y _{0 .15} O _{3 -δ} with 15 mol% of Y added with sintering additive CuO.
4 is a graph showing sintering shrinkage curves of an anode support and an electrolyte obtained in an embodiment of the present invention.
5 is a SEM photograph of the cross-sectional microstructure of the anode support and the electrolyte membrane obtained in the embodiment of the present invention.

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The present invention consists of a technique for improving the degree of sintering by adding an additive to an electrolyte to obtain a dense electrolyte layer and a simultaneous sintering technique for sufficiently shrinking the electrolyte layer by coating the electrolyte layer on the anode support and then sintering the same . INDUSTRIAL APPLICABILITY According to the present invention, it is possible to economically produce a high-performance high-output solid oxide fuel cell having a thin electrolyte layer, and the manufactured single cell is greatly improved in durability and reliability.
The core of the present invention is to suppress interface defects of various constituent layers constituting a unit cell, and in particular to suppress defects of an electrolyte layer having a thin and dense structure.

Generally, whether the electrolyte layer is densified or defect formation during the manufacturing process is greatly affected by the negative electrode support. In particular, since the shrinkage ratio of the electrolyte layer is limited by the shrinkage ratio of the negative electrode support, densification becomes difficult. Therefore, in order to form a dense electrolyte layer on the porous cathode support, a sufficient shrinkage ratio of the electrolyte layer should be ensured in sintering. For this purpose, a sintering additive is added to minimize the constraining effect (limiting sintering effect) which limits the sintering degree of the electrolyte layer by securing the shrinkage ratio of the negative electrode support, or to increase the sintering degree of the electrolyte having a low sintering degree. Can be used. The above two methods can be more effective when used in parallel.

A method of minimizing the effect of sintering by the negative electrode support is to simultaneously sinter the electrolyte layer with the shrinkage ratio of the support being maximized. At this time, sufficient strength should be obtained so that the support is not damaged when the electrolyte layer is formed. Also, in order to increase the sintering degree of the electrolyte itself during simultaneous sintering with the anode support, it is necessary to add a sintering additive to help densify the electrolyte layer. Specifically, in the embodiment of the present invention, sintering degree is improved by adding 4 mol% ZnO or 1 mol% CuO to BaZrO ₃ containing 15 mol% Y as a sintering additive.

Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to the examples.

Example

Sintering additive CuO Wow ZnO Added BaZr _{0 .85} Y _{0 .15} O ₃  Production step of sintered body

BaCO ₃ , ZrO ₂ , 15 mol% Y, and 4 mol% ZnO as a sintering additive were mixed and sintered at 1300 ° C. At this time, ZnO was substituted for Zr in the BaZrO ₃ crystal structure. The density was measured by the Archimedes method, and the relative density was 97%.

BaCO ₃ , ZrO ₂ , 15 mol% Y, and 1 mol% CuO as sintering additive were mixed and sintered at 1500 ° C. At this time, CuO was substituted for Zr in the BaZrO ₃ crystal structure. The density was measured by the Archimedes method, and the relative density was 99%.

The chemical formulas of the ceramic composition thus obtained are BaZr _{0 .81} Zn _{0 .04} Y _{0 .15} O _{3 -δ} and BaZr _0.84 Cu _0.01 Y _0.15 O _{3 -δ} .

FIG. 1 is a graph _showing the results of a comparison between BaZrO ₃ with 15 mol% of Y added without sintering additive and BaZr _{0 .81} Zn _{0 .04} Y _{0 .15} O ₃ with 15 mol% Y added with sintering additive ZnO and CuO _-δ and BaZr _0.84 Cu _0.01 Y _0.15 O _{3 -δ} .

FIG. 2 is a SEM micrograph of BaZr _{0 .81} Zn _{0 .04} Y _{0 .15} O _{3 -δ} with 15 mol% Y added with sintering additive ZnO. FIG. mol% Y added BaZr _0.84 Cu _0.01 Y _0.15 O _3-隆.

Production steps of a fuel cell cathode element comprising a cathode support and an electrolyte

The powder of the anode support was prepared by mixing NiO with 15 mol% of Y-added BaZr _{0 .81} Zn _{0 .04} Y _{0 .15} O _{3 -δ} added with the sintering additive ZnO at 40: 60 vol% . The powder was hot-pressed and plasticized at 1100 ° C to secure strength.

A paste for screen printing was prepared using the 15 mol% Y-added BaZr _{0 .84} Cu _{0 .01} Y _{0 .15} O _{3 -δ} powder to which the CuO was added, and the electrolyte paste was applied to the cathode Screen-printed on the substrate twice, and sintered simultaneously at 1500 ° C.

The sintering temperature of BaZrO ₃ added without sintering additive should be higher than 1700 ℃, but the sintering temperature was lowered to 1500 ℃ by adding sintering additive to cathode support and electrolyte. 4 is a graph showing sintering shrinkage curves of an anode support and an electrolyte obtained in an embodiment of the present invention. Similar sintering behavior could be obtained by adding different sintering additives to the anode support and the electrolyte.

5 is a SEM photograph of the cross-sectional microstructure of the anode support and the electrolyte membrane obtained in the embodiment of the present invention. It can be confirmed that a porous cathode support and a thin and dense electrolyte membrane are formed.

Claims (4)

And a cathode support and an electrolyte for producing a fuel cell cathode element comprising an anode support comprising an ABO ₃ -based proton conductive ceramic of the following formula and an electrolyte by adding and sintering a sintering additive to the anode support, the electrolyte, or both Wherein the fuel cell is a cathode.
The
_{Ba (Zr 1-xy Y x} M y) O 3
here,
M is at least one of Cu and Zn,
x is 0 < x? 0.2 and y is 0 < y? 0.1. The method according to claim 1,
Wherein the cathode support and the electrolyte are co-sintered together, and an electrolyte. The method according to claim 1, wherein the sintering additive is ZnO or CuO, and an electrolyte. The method of manufacturing a fuel cell cathode element according to claim 1, wherein the cathode support is formed by a liquid phase coagulation method, and the electrolyte is formed by a screen printing method.

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