KR101288375B1 - Ceria based bi-layer electrolyte comprising yttria-stabilized zircornia functional layer formed via atomic layer deposition, and solid oxide fuel cell comprising the same - Google Patents

Abstract

The present invention relates to a ceria-based electrolyte including an yttria-stabilized zirconia functional layer formed by atomic film deposition and a solid oxide fuel cell including the same. It was confirmed that the electrolyte functional layer formed according to various embodiments of the present invention may exhibit various effects as follows. That is, ceria is protected from the reducing gas, electron insulation can be obtained, and the resistive loss can be minimized by thinly depositing a thin YSZ film having a relatively high resistance to oxygen ions, and the thickness of the functional layer can be easily controlled. There is little difference in the density of the membrane and is relatively strong to exposure to reducing gas. In addition, it is possible to deposit sub-nm thin films, large area deposition, excellent deposition uniformity and step coverage, multicomponent film deposition, and high deposition density and pinhole free layer. The advantage is that deposition is possible.

Description

Ceria based bilayer electrolyte comprising yttria-stabilized zircornia functional layer formed via atomic layer deposition, and solid oxide fuel comprising a yttria-stabilized zirconia functional layer formed by atomic film deposition cell comprising the same}

The present invention relates to a ceria-based electrolyte including an yttria-stabilized zirconia functional layer formed by atomic film deposition and a solid oxide fuel cell including the same.

The biggest barrier to the commercialization of solid oxide fuel cells, which is expected with next-generation energy conversion technologies due to hydrocarbon availability, must be durability under high temperature operating conditions. You need to use the production method. In addition, the prolonged exposure to high temperature environment has a problem of sealing, microstructural change of electrode material and diffusion of components, leading to deterioration of overall cell performance.

To solve this problem, SOFC can be manufactured by using ceria-based electrolyte instead of zirconia-based electrolyte for high temperature (800-1,000 ° C) operation such as yttria-stabilized zirconia (YSZ). The low cost of the lanthanum strontium gallate magnesite (LSGM) electrolyte shows that it is commercially available.

However, ceria electrolytes doped with rare earth materials, such as gadolinium doped ceria (GDC) and samarium doped ceria (SDC), have a Ce ⁴ electrolyte that is inevitably exposed for fuel cell operation. ⁺ there is a problem that the electronic conductivity significantly to the reduction reaction of Ce ^{3 +} in, due to this effect, such internal short circuit is displayed is a disadvantage, such as voltage drop and the power density decreases. Another disadvantage is weakness in mechanical strength and chemical stability compared to YSZ, which is also a problem to be solved as it is a big problem in durability and homeostasis for electrolytes that must be kept airtight.

The present invention not only overcomes these conventional problems, but also discloses an electrolyte functional layer that can exhibit various effects as follows. That is, ceria is protected from the reducing gas, electron insulation can be obtained, and the resistive loss can be minimized by thinly depositing a thin YSZ film having a relatively high resistance to oxygen ions, and the thickness of the functional layer can be easily controlled. There is little difference in the density of the membrane and is relatively strong to exposure to reducing gas. In addition, it is possible to deposit sub-nm thin films, large area deposition, excellent deposition uniformity and step coverage, multicomponent film deposition, and high deposition density and pinhole free layer. An electrolyte functional layer having the advantage of being capable of deposition is disclosed.

According to an aspect of the present invention, a method of manufacturing a double layer electrolyte for a solid oxide fuel cell including an YSZ functional layer, comprising: forming an YSZ functional layer by performing an atomic film deposition method, the YSZ for a solid oxide fuel cell Disclosed is a method of producing a functional layer-containing bilayer electrolyte. In the case of a solid oxide fuel cell including a double layer electrolyte including an YSZ functional layer formed by atomic film deposition, it was confirmed that electron insulation and chemical stability are significantly improved as compared with the case of conventionally manufactured by other methods.

According to one embodiment, forming the YSZ functional layer by performing the atomic film deposition method comprises (a-1) supplying an yttria precursor into the chamber, (a-2) purging the chamber, (a -3) supplying an oxidant into the chamber, (a-4) an yttria formation cycle consisting of purging the chamber, and (b-1) supplying one of the zirconia precursors into the chamber (b-2) purging the chamber, (b-3) supplying an oxidant into the chamber, and (b-4) purging the chamber 1-30 times each. Disclosed is a method of manufacturing a double layer electrolyte including an YSZ functional layer for a solid oxide fuel cell, which is repeatedly performed.

According to another embodiment, the yttria precursor is tris- (methylcyclopentadienyl) yttrium, the zirconia precursor is tetrakis (dimethylamido) zirconium, and the oxidant is deionized water. Disclosed is a method for producing a bilayer electrolyte including a battery YSZ functional layer.

According to another embodiment, a double layer including an YSZ functional layer for a solid oxide fuel cell, characterized in that the yttria formation cycle and the number of cycles of the zirconia formation cycle are controlled such that the yttria content is 5-10% in the YSZ functional layer. A method for producing an electrolyte is disclosed. Alternatively, a method of manufacturing a double layer electrolyte including an YSZ functional layer for a solid oxide fuel cell is disclosed, wherein the yttria forming cycle and the zirconia forming cycle are performed at a ratio of 1: 5-10. In this case, it was confirmed that the oxygen ion conductivity of the YSZ is maximized. Also, when it is performed outside the above range, it was confirmed that the electron insulation is not performed.

According to one embodiment, the yttria formation cycle is performed to be deposited at a rate of 1.5-2.5 kW / cycle, and the zirconia formation cycle is performed to be deposited at a rate of 1-1.5 kW / cycle. Disclosed is a method for producing a double layer electrolyte including an YSZ functional layer for a fuel cell. In this case, it was confirmed that the deposition uniformity and the deposition density were greatly improved, and if it was out of the above range, partial damage of ceria by the reducing gas could occur.

According to another embodiment, a method of manufacturing a double layer electrolyte including an YSZ functional layer for a solid oxide fuel cell, wherein the yttria forming cycle and the zirconia forming cycle are performed such that an overall YSZ stacking rate is 1.3-1.7 μs / cycle. Is initiated. In this case, it was confirmed that the deposition uniformity and the deposition density were greatly improved, and when outside the above range, pinholes could be generated in the deposition layer.

According to another embodiment, the steps (a-1) to (a-4) and (b-1) to (b-4) are for a solid oxide fuel cell, characterized in that performed at 200-300 ℃ Disclosed is a method for producing a bilayer electrolyte comprising an YSZ functional layer. In this case, only by the chemisorption reaction on the surface can be controlled by the atomic layer unit can be obtained the effect of forming a thin film, it was confirmed that the effect can not be achieved when performed outside the above range.

According to another aspect of the invention, (A) fixing the GDC powder in the form of pellets using a mold and a press, (B) compressing the pellet at 1,000-2,500 bar, (C) the pellet 1,000-2, Sintering at 0000 ° C., (D) grinding the pellet, (E) polishing the pellet, (F) depositing an YSZ layer on one side of the pellet by atomic film deposition, (G Annealing the pellet on which the YSZ layer is deposited at 500-900 ° C. to complete the electrolyte, (H) screen printing an anode material paste on the electrolyte surface on which the YSZ layer is deposited, and (I) the anode material is Sintering the screen printed electrolyte to 1,000-1,500 ° C., (J) screen printing a cathode material paste on the opposite side of the electrolyte surface on which the YSZ layer is deposited, (K) screen printing the anode material High temperature electrolyte Disclosed is a method of manufacturing a solid oxide fuel cell including a bilayer electrolyte including an YSZ functional layer, which includes sintering at 1,000-1,500 ° C. in an electric furnace.

According to an embodiment, the step (F) may be performed by a method of manufacturing a double layer electrolyte including an YSZ functional layer for a solid oxide fuel cell according to various embodiments of the present disclosure.

It was confirmed that the electrolyte functional layer formed according to various embodiments of the present invention may exhibit various effects as follows. That is, ceria is protected from the reducing gas, electron insulation can be obtained, and the resistive loss can be minimized by thinly depositing a thin YSZ film having a relatively high resistance to oxygen ions, and the thickness of the functional layer can be easily adjusted. There is little difference in coverage and density of the formed film and is relatively strong to exposure to reducing gas. In addition, it is possible to deposit sub-nm thin films, large area deposition, excellent deposition uniformity and step coverage, multicomponent film deposition, and high deposition density and pinhole free layer. The advantage is that deposition is possible.

In addition, when manufacturing the SOFC including the electrolyte functional layer formed as described above, the deposition uniformity and the deposition density are high, so that the maximum protection of ceria from the reducing gas, ionic conductivity can be maximized, and the thickness of the deposited film can be minimized. The advantage is that the loss of resistance, which is a large loss, can be minimized.

1 is a view schematically showing a concept for explaining the present invention.
2 is a schematic of an ALD process for depositing a thin film of two materials.
3 and 4 illustrate a procedure for fabricating a bilayer electrolyte-supported SOFC using a thin film process.
5 is a graph comparing the points showing the highest output of the double-layer electrolyte cells excluding ALD and the performance prediction curve of SOFC applying the electrolyte using ALD.
6 is a graph showing the electronic conductivity expressed due to reduction in ceria at each temperature and oxygen partial pressure environment.

The present invention discloses a SOFC to which a bilayer electrolyte including an YSZ functional layer formed by atomic layer deposition (ALD) is applied, whereby electron insulation and chemical stability are greatly improved.

The atomic layer deposition (ALD) employed in the present invention is a thin film deposition method that is a special modification of chemical vapor deposition (CVD) to induce self-limiting growth of a thin film. At this time, most of the electrolyte thickness was occupied by ceria-based materials such as GDC and SDC, and it was confirmed that YSZ was deposited on the electrolyte side of the anode through a thin film process.

In this case, when the metal oxide film is deposited by chemical vapor deposition, the metal precursor to be deposited as a thin film and the oxidant gas are simultaneously supplied to the reactor to form a thin film by thermal decomposition and surface reaction thereof. In the ALD method, the metal precursor and the oxidant gas are formed. As the supply of is carried out sequentially, a purging step is added between the supplying step of the metal precursor and the oxidant to remove residual gas and reaction byproducts from the reactor with an inert gas which is not reactive such as Ar. Therefore, the ALD process employed in the present invention includes a process cycle consisting of four steps: (1) precursor supply, (2) purge, (3) oxidant supply, and (4) purge, and the deposition is performed in one cycle. The cycle is repeated to deposit a thin film.

In addition, all these processes were carried out at less than 300 ℃, it was confirmed that only the chemical adsorption reaction on the surface of the atomic layer unit to form a thin film.

Specific conditions for depositing an YSZ thin film on a ceria substrate using an ALD equipment and an ALD process for depositing a thin film of two materials are shown in Tables 1 and 2, respectively.

As such, the method of depositing a thin film functional layer forms a high-density thin film using ALD on a doped ceria substrate, which protects ceria from reducing gas, electronic insulation, and relatively resistance of oxygen ions. Thin deposition of a large YSZ film serves to minimize ohmic loss.

Previously, there have been reports of electrolyte functional layer deposition using wet process such as screen printing, dip coating, spin coating, sputtering, thin film process such as plasma laser deposition, and CVD method, but functional layer deposition using ALD Previous studies on the situation have not been reported.

Therefore, in the case of performing the electrolyte functional layer deposition according to various embodiments of the present invention, (1) thin films of sub-nm can be deposited, (2) large-area deposition is possible, and (3) deposition uniformity and step coverage. (step coverage) is excellent, (4) multi-component film deposition is possible, (5) high deposition density and pinhole-free layer deposition is possible.

In addition, when fabricating the SOFC including the electrolyte functional layer formed as described above (1) high deposition uniformity and deposition density, it is possible to maximize protection of ceria from reducing gas and maximize ion conductivity, (2) minimize the thickness of the deposited film This can minimize the resistive loss, which is the biggest loss of SOFC.

In an embodiment of the present invention, commercial precursors of Sigma Aldrich and Strem Chemical were used as sources of yttria oxide (yttria) and zirconium oxide (zirconia), which are two materials of yttria-stabilized zirconia (YSZ). In addition, deionized water (DI water) was used as an oxidizing agent because each substance was an oxide. In addition, the temperature in the ALD chamber was 230 ℃, the cycle ratio of each precursor is exposed to 7: 1 so that the yttria ratio is 8%, it was confirmed that the oxygen ion conductivity of YSZ is maximized. YSZ deposition rate was adjusted to be 1.4-1.5 Hz per cycle.

As shown in FIGS. 3 and 4, the procedure for fabricating a bilayer electrolyte-supported SOFC using a thin film process is as follows: (1) temporarily fixing the GDC powder in pellet form using a mold and a press, and (2) using a CIP apparatus. Compacting the pellets at 1,800 bar, (3) sintering at 1,400 ° C. in a high temperature furnace, (4) grinding the sintered pellets to the desired shape and thickness, (5) diamond sand furnace Polishing both sides, (6) performing ALD on the YSZ layer on one side, (7) annealing at 800 ° C. to complete the electrolyte, and (8) screening the anode material paste on the electrolyte side with YSZ Printing, (9) sintering at 1,400 ° C. in a high temperature furnace, (10) screen printing a cathode material paste on the electrolyte side without YSZ, and (11) sintering at 1,100-1,200 ° C. in a high temperature furnace. And a step.

The bilayer electrolyte SOFC utilizing existing thin film processes such as sputtering, pulsed laser deposition, CVD, etc., is not easy to control the thickness of the functional layer compared to the ALD deposition method disclosed in various embodiments of the present invention. The difference in the step coverage and the density of the formed film is vulnerable to exposure to reducing gases, and does not guarantee electron insulation.

Points shown in FIG. 5 indicate the highest output values in the literature for measuring performance by making a double layer electrolyte cell except for ALD. However, since these double layer electrolytes are those of relatively thin (10-100 μm) electrolyte-supported cells, for the satisfactory comparison with the above experiments, the most inferred solid line is drawn based on the performance of the current 500 μm cell. At 20 μm, this yields significantly higher output density estimates for both 600 ° C and 650 ° C. This makes it possible to explain the superiority of the preparation of the double layer electrolyte using ALD.

Application of various embodiments of the present invention lowers the operating temperature of the SOFC, and thus has the effect of economical efficiency, durability, and the like. In addition, if a high-temperature SOFC can be driven, a higher output density and efficiency can be manufactured. Can be. This is because the higher the temperature, the higher the CIA's electronic conductivity is expressed in the low oxygen partial pressure atmosphere, and if it is effectively blocked by the YSZ functional layer, it is obvious that it will be a high output SOFC without internal short circuit. Therefore, there is no need to be concerned with the operating temperature, so all the fields that can be applied to SOFC such as power generation and portable can be the market.

Claims (16)

delete delete delete delete delete A method for producing a double layer electrolyte for a solid oxide fuel cell comprising an YSZ functional layer;
Forming an YSZ functional layer by performing atomic film deposition;
Forming an YSZ functional layer by performing the atomic film deposition method includes (a-1) supplying an yttria precursor into the chamber, (a-2) purging the chamber, (a-3) into the chamber Supplying an oxidant, (a-4) an yttria formation cycle consisting of purging the chamber, and (b-1) feeding one of the zirconia precursors into the chamber, (b-2) Purging the zirconia forming cycle consisting of purging the chamber, (b-3) feeding an oxidant into the chamber, and (b-4) purging the chamber;
The yttria precursor is tris- (methylcyclopentadienyl) yttrium, the zirconia precursor is tetrakis (dimethylamido) zirconium, and the oxidant is deionized water;
Adjusting the number of yttria forming cycles and the number of zirconia forming cycles so that the yttria content in the YSZ functional layer is 5-10%;
The yttria formation cycle and the zirconia formation cycle are performed at a ratio of 1: 5-10;
The yttria formation cycle is performed to be deposited at a rate of 1.5-2.5 kW / cycle, and the zirconia formation cycle is performed to be deposited at a rate of 1-1.5 kW / cycle. Method for producing a double layer electrolyte. The method of claim 6, wherein the yttria formation cycle and the zirconia formation cycle are performed such that the total YSZ deposition rate is 1.3-1.7 kPa / cycle. The YSZ of claim 7, wherein the steps (a-1) to (a-4) and the steps (b-1) to (b-4) are performed at 200-300 ° C. Method for producing a bilayer electrolyte containing a functional layer. A method of manufacturing a solid oxide fuel cell comprising a bilayer electrolyte comprising an YSZ functional layer comprising the following steps:
(A) fixing the GDC powder in pellet form using a mold and a press,
(B) compacting the pellets at 1,000-2,500 bar,
(C) sintering the pellet at 1,000-2,0000 ° C.,
(D) grinding the pellets,
(E) polishing the pellets,
(F) depositing an YSZ layer on one side of the pellet by atomic film deposition;
(G) annealing the pellet deposited with the YSZ layer at 500-900 ° C. to complete the electrolyte,
(H) screen printing an anode material paste on the electrolyte surface on which the YSZ layer is deposited;
(I) sintering the electrolyte with the anode material screen printed to 1,000-1,500 ° C.,
(J) screen printing a cathode material paste on the opposite side of the electrolyte surface on which the YSZ layer is deposited;
(K) sintering the anode screened electrolyte at 1,000-1,500 ° C. in a high temperature electric furnace. The method of claim 9, wherein (F) comprises: (a-1) supplying an yttria precursor into the chamber, (a-2) purging the chamber, and (a-3) supplying an oxidant into the chamber. (A-4) an yttria formation cycle consisting of purging the chamber, and (b-1) supplying one of the zirconia precursors into the chamber, (b-2) the chamber YSZ, wherein the zirconia formation cycle consisting of the step of purging, (b-3) supplying an oxidant into the chamber, and (b-4) purging the chamber are repeated 1-30 times each. A method of manufacturing a solid oxide fuel cell comprising a bilayer electrolyte with a functional layer. The YSZ functional layer according to claim 10, wherein the yttria precursor is tris- (methylcyclopentadienyl) yttrium, the zirconia precursor is tetrakis (dimethylamido) zirconium, and the oxidizing agent is deionized water. A method of manufacturing a solid oxide fuel cell comprising a bilayer electrolyte. 12. The solid comprising the bilayer electrolyte of the YSZ functional layer of claim 11, wherein the yttria formation cycle and the number of the zirconia formation cycles are controlled so that the yttria content is 5-10% in the YSZ functional layer. Method of manufacturing an oxide fuel cell. The method of claim 12, wherein the yttria forming cycle and the zirconia forming cycle are performed at a ratio of 1: 5-10. The YSZ function of claim 13, wherein the yttria forming cycle is performed to be deposited at a rate of 1.5-2.5 kW / cycle, and the zirconia forming cycle is performed to be deposited at a rate of 1-1.5 kW / cycle. A method of manufacturing a solid oxide fuel cell comprising a bilayer electrolyte with layers. 15. The solid oxide fuel cell of claim 14, wherein the yttria forming cycle and the zirconia forming cycle are performed such that an overall YSZ deposition rate is 1.3-1.7 dl / cycle. Manufacturing method. 16. The bilayer according to claim 15, wherein the steps (a-1) to (a-4) and the steps (b-1) to (b-4) are performed at 200-300 ° C. A method of manufacturing a solid oxide fuel cell comprising an electrolyte.

Images