KR20160030677A - Support for micro-solid oxide fuel cell and manufacturing method for micro-solid oxide fuel cell - Google Patents

Abstract

The present invention relates to a metal support comprising a metal support having a plurality of open pores in a fuel cell manufactured through a thin film process and an intermediate layer having a plurality of open pores smaller than the open pores of the metal support, so as to implement a solid oxide fuel cell without passing through a lithography process and an etching process, and to a method for manufacturing a micro-solid oxide fuel cell having the metal support. According to the present invention, a metal support for a micro-solid oxide fuel cell comprises: a metal support having a plurality of open pores; and an intermediate layer having open pores smaller than the open pores of the metal support on average on the metal support.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a support for a micro solid oxide fuel cell and a method for manufacturing the micro solid oxide fuel cell.

The present invention relates to a support for a micro solid oxide fuel cell and a method of manufacturing a micro solid oxide fuel cell comprising the same, and more particularly, to a fuel cell manufactured by a thin film process, a metal support having a plurality of open pores, A metal support having an intermediate layer having a plurality of open pores having a smaller pore size than the metal support and capable of realizing a solid oxide fuel cell without performing a lithography process and an etching process and a manufacturing method of a micro solid oxide fuel cell having the metal support ≪ / RTI >

A solid oxide fuel cell (SOFC) has a structure in which a plurality of electricity generating units each comprising a unit cell and a separator plate are stacked. The unit cell includes a solid electrolyte layer and a cathode located on one surface of the solid electrolyte layer and a cathode located on another surface of the solid electrolyte layer.

Solid oxide fuel cells have the advantage of higher energy conversion efficiency and less pollution compared with other fuel cells, and can generate electricity without fuel reformer even when using various fuels such as natural gas in addition to hydrogen fuel.

In addition, it has high power density and various designs according to the applications. It can be used as a next generation energy source to replace existing power generation systems in a wide range of fields from large cogeneration systems to automobile auxiliary power systems and small and medium power systems such as portable power systems. It is getting attention.

These solid oxide fuel cells are mainly developed and applied to an electrolyte support body and a cathode support body. However, in such a configuration, all of the constituent elements of the unit cell are made of ceramic, which is mechanically weak.

The following Patent Document 1 discloses a porous ceramic support as a fuel electrode support. However, due to the brittleness of the ceramic material itself, it has low impact resistance, is vulnerable to thermal shock due to low thermal conductivity, and is difficult to drive quickly. Further, there is a problem that the unit cell may be broken due to the external pressure applied to stack the unit cells to improve the current collecting state during the manufacture of the stack.

In order to solve such a problem, researches on a metal support type solid oxide fuel cell are under way. The solid oxide fuel cell of the metal support type has a high thermal conductivity of the metal support and resistance to thermal shock and mechanical shock due to the mechanical strength and ductility of the metal.

 Ferritic Fe-Cr steel is inexpensive because it does not contain expensive nickel (Ni), and its thermal expansion coefficient is similar to the electrolyte of a solid oxide fuel cell, so that it has high resistance to thermal cycling. Therefore, solid oxide fuel cells using ferrite-based Fe-Cr steel as a support can be widely used for small-sized, home-use, small portable and mobile power sources.

On the other hand, solid oxide fuel cells to be used in small portable and mobile power sources are required to operate at a low temperature of 600 ° C or less due to rapid operation for carrying and limitations of the system volume and insulation technology. In order to maintain high performance at a low temperature, a micro-SOFC (micro-SOFC) having a thin film of the constituent elements (electrode and electrolyte) of a unit cell is in the spotlight. Technological developments have been started on a micro solid oxide fuel cell in which a component is made thinner.

However, the electrolyte-supported or metal-supported solid oxide fuel cell based on a thin film that has been developed to date has a problem in that a negative electrode, an electrolyte, and a positive electrode are sequentially deposited on a metal or glass substrate having a dense structure as disclosed in Patent Document 2 A wet or dry etching method is used to inject the fuel into the dense support. However, the thin film formed on the support may be damaged during the etching process and the lithography process must be performed. Therefore, the process is complicated and costly.

Korean Patent Laid-Open Publication No. 2013-0075266 Korean Registered Patent No. 10-1002044

The object of the present invention is to provide a support for a solid oxide fuel cell capable of realizing a solid oxide fuel cell without the lithography process and the etching process required for a porous metal substrate for manufacturing a conventional thin film material-based solid oxide fuel cell .

Another object of the present invention is to provide a solid oxide fuel cell including the support for the solid oxide fuel cell.

According to an aspect of the present invention, there is provided a metal support comprising: a metal support including a plurality of open pores; and an intermediate layer including open pores having an average pore size smaller than the open pores of the metal support, A support for a micro solid oxide fuel cell is formed.

According to another aspect of the present invention, there is provided a method of manufacturing a semiconductor device, Laminating the intermediate layer on the metal support using a warm isostatic pressing (WIP) process; Heat treating the metal support having the intermediate layer stacked thereon; And laminating a cathode thin film, an electrolyte thin film, and a cathode thin film sequentially on the intermediate layer.

The support for a solid oxide fuel cell according to the present invention has a structure in which an intermediate layer having small pores is formed on a metal support having open pores of a large size that facilitates mass transfer, The etching process or the lithography process performed to form the intermediate layer is not required and the intermediate layer has a dense structure as compared with the metal support so that the cell structure formed on the intermediate layer is easily formed do.

In addition, according to one embodiment of the present invention, since a support is manufactured by a method such as screen printing or tape casting, a simple and large-area thin-film-material-based solid oxide fuel cell is manufactured .

In addition, according to one embodiment of the present invention, since a metal support based on a ferrite-based Fe-Cr steel is used, it is possible to realize a solid oxide fuel cell in which thermal and mechanical stability is ensured.

FIG. 1 is a scanning electron micrograph of an LSTN-YSZ intermediate layer and a metal support of a support for a solid oxide fuel cell in which a metal support prepared according to an embodiment of the present invention and an LSTN-YSZ intermediate layer are formed.
2 schematically shows the structure of a solid oxide fuel cell manufactured according to an embodiment of the present invention.
3 is a scanning electron micrograph of a cross section of a solid oxide fuel cell fabricated according to an embodiment of the present invention.
4 is a graph illustrating a voltage-current power characteristic of a solid oxide unit battery according to an embodiment of the present invention.
5 is a graph comparing power characteristics of a solid oxide unit battery manufactured according to an embodiment of the present invention in a hydrocarbon and hydrogen atmosphere at 550 ° C.

In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear. Also, when a component is referred to as "comprising ", it is meant to include other components as well, without departing from the other components unless specifically stated otherwise.

Also, unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

The support for a micro solid oxide fuel cell according to the present invention comprises a metal support including a plurality of open pores and an open pore having an average pore size smaller than the open pores of the metal support, And an intermediate layer is formed.

Since the present invention uses a metal support including open pores, it is not necessary to perform a process of etching and lithography of a metal support having a dense structure as in the prior art, thereby realizing a low-cost process. In addition, a thin film battery structure can be formed on the support by forming an intermediate layer on the open pore metal support having a dense structure with a smaller pore size than the open pores of the metal support.

Various metals may be used for the metal support, but ferritic Fe-Cr steel is preferred. At this time, various alloying elements may be added to the ferrite-based Fe-Cr steel (i.e., ferritic stainless steel) without any particular limitations as long as it can retain the ferrite structure.

The intermediate layer may have a size gradient such that the pore size decreases continuously or intermittently from the metal support to the upper portion. When the size gradient is set as described above, the pore size difference between the metal support and the surface of the intermediate layer can be greatly increased, and the more compact the surface of the intermediate layer, the higher the integrity of the battery element formed on the intermediate layer. For example, the intermediate layer may have a multi-layer structure in which the pore size decreases toward the upper part.

If the thickness of the metal support is less than 1 탆, the mechanical strength is lowered. If the thickness is more than 1000 탆, heat dissipation is not smooth during high-speed driving due to increase of thermal mass. In addition, when the average pore size of the metal support is less than 1 μm, mass transfer is not smooth. When the average pore size exceeds 900 μm, the mechanical strength of the support is limited.

When the thickness of the intermediate layer is less than 1 탆, surface defects are likely to occur due to rough unevenness of the metal support. When the thickness exceeds 100 탆, it is difficult to smoothly move the gas. When the pore size is less than 10 nm, the movement of the material is not smooth. When the pore size is more than 500 nm, it is difficult to coat the thin film electrolyte having a thickness of 1 탆 or less.

Since the intermediate layer must electrically connect the metal support to the thin film anode formed on the upper portion, the intermediate layer should be formed of a conductor, and preferably, a composite material of an oxide electron conductor and an ion conductor.

If the oxide electronic conductor, typically, is to be perovskite (perovskite) structure (ABO ₃₎ of an oxide having, SrTiO _3, YCrO _3, the dual-doped LaCrO ₃ in the composition. At this time, Y and La are doped into Sr of SrTiO ₃ , and Ti, Ni, Co, Cu, Fe, Mn, Zn, Pd, or Ru can be substituted with a dopant. In the case of YCrO ₃ or LaCrO ₃ , La may be doped with Sr, Ba, Ca or Mg, and Cr may be substituted with a dopant such as Ni, Co, Cu, Fe, Mn, Zn, Pd or Ru.

Specifically, the oxide electron conductor is represented by A _x Y _1-x M _y Cr _1-y O ₃ (0.01 _{? X} ? 0.5, 0.01 _{? Y?} 0.3, A is La and M is Ni, Co, Cu, Fe, Mn (Where 0.01? X? 0.5, 0.01? Y? 0.3, A represents Y, and M represents Ni, Co, and the like), A _x La _1-x M _y Cr _1-y O ₃ Cu, Fe, Mn, Zn, Pd, Ru, or mixtures _{thereof), a x Sr 1-x} M y Ti 1-y O 3 (0.01≤x≤0.5, 0.01≤y≤0.3, a is y, La , Or a mixture thereof, M may be Ni, Co, Cu, Fe, Mn, Zn, Pd, Ru, or a mixture thereof.

The intermediate layer may further comprise an ion conductor such as Accepter-doped zirconia, Ceria, Lanthanum Strontium Gallate Magnesite (LSGM), or a mixture thereof. Mixing of such an ion conductor and an oxide electron conductor can suppress severe sintering which may occur when only one composition is formed, and is advantageous for controlling the pore size of the intermediate layer.

Of the composition of the electron conductor constituting the intermediate layer, Ni, Co, Cu, Fe, Mn, Zn, Pd, Ru or a mixture thereof which is a metal element doped to Ti or Cr is added to the perovskite oxide After being solidified, it can be exonerated to a nanoscale on a porous surface when exposed to a high temperature reducing atmosphere, and such nano-sized precipitates can function as a catalyst for hydrocarbon reforming and electrode reactions.

Further, the M element doped in the intermediate layer may be precipitated on the surface of the pores formed in the intermediate layer. In this case, the precipitated M element contributes to the improvement of the electrical conductivity of the intermediate layer.

Also, a method of manufacturing a micro solid oxide fuel cell according to the present invention includes the steps of: preparing a metal support and an intermediate layer; Laminating the intermediate layer on the metal support using a warm isostatic pressing (WIP) process; Heat treating the metal support having the intermediate layer stacked thereon; And depositing a negative electrode thin film, an electrolyte thin film, and a positive electrode thin film sequentially on the intermediate layer.

The metal support and the intermediate layer may be formed by screen printing, tape casting, aerosol deposition, spray coating, spin coating, or dip coating. . ≪ / RTI >

Further, the heat treatment step is preferably performed in a reducing atmosphere or an inert atmosphere, and when the heat treatment is performed in a reducing atmosphere or an inert atmosphere, precipitation of the M component can be promoted. In addition, when the heat treatment is performed at a temperature of less than 800 ° C., a weak bonding force is generated between the interlayer and the layer forming powder, and the M element doped in the intermediate layer hardly precipitates. When the annealing is performed at a temperature exceeding 1500 ° C., It is difficult to obtain a preferable pore size, and therefore, it is preferably 800 to 1500 ° C.

In addition, since the sintering temperature is not saturated when the time is less than 2 hours, and the sintering temperature is more than 4 hours, it is preferably 2 hours to 4 hours.

The heat treatment step may control the electric conductivity of the intermediate layer through the heat treatment temperature and the partial pressure of the inert gas.

Hereinafter, the present invention will be described in detail based on preferred embodiments of the present invention. These embodiments are only for illustrating the present invention, and the present invention is not limited thereto.

Support manufacturing

Metal oxide powder which is reduced to metal powder or metal is ball milled with polymer solution (toluene (Toluene + Ethanol + Polyvinyl butyral + Dioctyl phthalate) To obtain a slurry, and the obtained slurry is subjected to a known tape casting method to prepare a green sheet.

At this time, an appropriate amount of ceramic powder such as graphite powder, pore fomer such as starch, zirconia, alumina and the like is added to the metal oxide powder which is reduced to the metal powder or metal By metal The porosity and pore size of the support can be controlled.

More specifically, in the embodiment of the present invention, ferrite-based Fe-Cr steel powder having an average particle size of about 25 to 30 μm was used as a metal oxide powder, and 5% of starch as a pore precursor was added The mixture was mixed with a polymer solution (toluene (Toluene) + ethanol (Ethanol) + polyvinyl butyral) and ball milled for 48 hours to obtain a slurry.

A ferrite-based Fe-Cr steel green sheet having a thickness of about 40 탆 or less was prepared by using the tape casting equipment thus obtained.

Next, a La _{0 .2} Sr _{0 .8} Ti _{0 .9} Ni _{0 .1} O _{3 -δ} powder and a Yttria stabilized zirconia (YSZ) powder were mixed at a mass ratio of 7: 3, and a polymer solution (toluene + Mixed with ethanol / polyvinyl butyral to prepare a mixed powder slurry having an average particle size of 1 탆 or less through planetary ball milling. Using this tape casting equipment, An LSTN-YSZ green sheet having a thickness of 30 μm or less was prepared.

The thus prepared ferrite-based Fe-Cr steel green sheet and the LSTN-YSZ green sheet were laminated using a laminator and heated at a temperature of 80 占 폚 using Warm isostatic pressure (WIP) At a pressure of 4000 psi (Pound per Square Inch) to obtain a laminate.

The thus obtained laminate having a two-layer structure was punched to a diameter of 1 cm and then heat-treated and sintered in a hydrogen gas atmosphere at 1250 to 1260 DEG C for 3 hours to obtain a support for a solid oxide fuel cell equipped with a metal support and an intermediate layer Respectively.

Microstructure evaluation

FIG. 1 is a photograph of a multilayer porous support prepared according to an embodiment of the present invention, taken by a scanning electron microscope immediately after sintering, wherein (a) shows the surface of LSTN-YSZ and (b) shows a cross section of the porous metal support.

As a result of analyzing the LSTN-YSZ surface image in FIG. 1 (a), it was confirmed that the porosity was 12% and the pore size was several tens of nanometers to several hundreds of nanometers.

1 (b) is an LSTN-YSZ layer and the lower coarse portion is a ferrite-based Fe-Cr steel. The thickness of the intermediate layer is 30 占 퐉 to 40 占 퐉, and the thickness of the metal support is 300 占 퐉 - And it is confirmed that it is formed to have a thickness of 400 mu m. Also, as a result of the cross-sectional image analysis, it was confirmed that the porosity of the ferrite-based Fe-Cr steel support was 18 to 28% and the pore size had several mu m to several tens of mu m.

Unit cell manufacturing

FIG. 2 is a schematic view showing a structure of a solid oxide fuel cell fabricated according to an embodiment of the present invention, and FIG. 3 is a cross-sectional view of a solid oxide fuel cell fabricated according to an embodiment of the present invention taken with a scanning electron microscope It's a picture.

2, a solid oxide fuel cell according to an embodiment of the present invention includes a metal support having pores of micro size, an intermediate layer having pores of sub micro size (nano size) on the metal support, A thin film negative electrode formed on the intermediate layer, a thin film electrolyte formed on the thin film negative electrode, and a thin film positive electrode formed on the thin film electrolyte.

The thin-film cathode, the thin-film electrolyte and the thin-film anode may be sequentially deposited by a PLD (Pulsed Laser Deposition) method.

Specifically, an anode made of Ni-YSZ and an electrolyte made of YSZ were deposited at a temperature of 600 ° C. and an oxygen partial pressure of 3 mTorr and 5 mTorr, respectively, to form thin films having thicknesses of about 0.7 μm and 2 μm, respectively. In addition, La _{0 .7} Sr _{0 .3} anode consisting of CoO ₃ (LSC) is deposited at room temperature, the oxygen partial pressure was 2 mTorr conditions to form a thin film thickness of about 0.5㎛, thus formed cell structure is shown in Figure 3 Same as.

Evaluation of power characteristics

FIG. 4 is a graph illustrating voltage-current power characteristics of a solid oxide unit battery manufactured according to an embodiment of the present invention. FIG. 5 is a graph illustrating a voltage versus current characteristic of a solid oxide unit battery according to an embodiment of the present invention. Lt; RTI ID = 0.0 > C, < / RTI >

The solid oxide unit battery prepared as in the present invention was exposed to air and the anode was subjected to a voltage-current characteristic evaluation using hydrogen gas (H ₂ 97% to H ₂ O 3%) as a fuel at 450 to 550 ° C. As shown in FIG. 4, the maximum output was 560 mW / cm 2 at 550 ° C.

Also, as shown in FIG. 5, the solid oxide unit battery manufactured according to the embodiment of the present invention showed a conversion efficiency of 60% in a hydrocarbon atmosphere when exposed to a hydrogen and hydrocarbon atmosphere at 550 ° C.

When the metal element (Ni, Co, Cu, Fe, Mn, Zn, Pd, or Ru) doped in Ti or Cr among the composition of the electron conductor constituting the intermediate layer is exposed to the high temperature and reducing atmosphere, It can be seen that the precipitation occurs at the nano size of the element and the deposited precipitate functions as a catalyst for the hydrocarbon reforming and the electrode reaction.

Claims (13)

A metal support including a plurality of open pores,
An intermediate layer including open pores having an average pore size smaller than that of the open pores of the metal support is formed on the metal support. The method according to claim 1,
Wherein the metal support is made of ferritic Fe-Cr steel. 3. The method according to claim 1 or 2,
Wherein the intermediate layer has a size gradient such that the pore size decreases continuously or intermittently from the metal support to the upper portion thereof. 3. The method according to claim 1 or 2,
The metal support has a thickness of 1 탆 to 1000 탆,
A support for a micro-solid oxide fuel cell having an average pore size of 1 탆 to 900 탆. 3. The method according to claim 1 or 2,
The intermediate layer has a thickness of 1 탆 to 100 탆,
A support for a micro-solid oxide fuel cell having an average pore size of 10 nm to 500 nm. 3. The method according to claim 1 or 2,
Wherein the intermediate layer comprises at least _one selected from the group consisting of A _x Y _{1 - x} M _y Cr _{1 - y} O ₃ (0.01 x 0.5, 0.01 _y x 0.3, A is La, M is Ni, Co, Cu, Fe, , Ru, or a mixture thereof), A _x La _{1 -x} M _y Cr _{1 -y} O ₃ (0.01? X? 0.5, 0.01? Y? 0.3, A is Y, M is Ni, Co, Mn, Zn, Pd, Ru or a mixture thereof), A _x Sr _1-x M _y Ti _1-y O ₃ (0.01? X? 0.5, 0.01? Y? 0.3, A is Y, La, And M is at least one selected from the group consisting of Ni, Co, Cu, Fe, Mn, Zn, Pd, Ru, or mixtures thereof. The method according to claim 6,
And the M element doped in the intermediate layer is deposited on the surface of the pores formed in the intermediate layer. The method according to claim 6,
Wherein said intermediate layer further comprises Accepter-doped zirconia, Ceria, Lanthanum Strontium Gallate Magnesite (LSGM), or mixtures thereof. Preparing a metal support and an intermediate layer;
Laminating the intermediate layer on the metal support using a warm isostatic pressing (WIP) process;
Heat treating the metal support having the intermediate layer stacked thereon; And
And stacking a cathode thin film, an electrolyte thin film, and a cathode thin film in this order on the intermediate layer. 10. The method of claim 9,
Wherein the metal support comprises a ferritic Fe-Cr steel. 11. The method according to claim 9 or 10,
The metal support and the intermediate layer may be any of screen printing, tape casting, aerosol deposition, spray coating, spin coating, or dip coating. A method of manufacturing a micro solid oxide fuel cell. 11. The method according to claim 9 or 10,
Wherein the heat treatment step is performed in a reducing atmosphere or an inert atmosphere at a temperature ranging from 800 to 1500 占 폚 for 2 to 4 hours. 11. The method according to claim 9 or 10,
Wherein the electrical conductivity of the intermediate layer is controlled by controlling the temperature of the heat treatment and the partial pressure of the inert gas in the heat treatment step.

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