KR102291279B1 - MCFC cathode to reduce nickel melt - Google Patents

Abstract

The present invention relates to a cathode for a molten carbonate fuel cell (MCFC) surface-coated on the cathode through an atomic layer deposition (ALD) method and a method for manufacturing the same, and more particularly, to an Al ₂ O ₃ , ZrO ₂ , YSZ, YDC, etc. to suppress the melting of Ni into the molten carbonate electrolyte at high temperature by coating the cathode for a molten carbonate fuel cell (MCFC) and a method for manufacturing the same. Since the cathode according to the present invention suppresses the elution of Ni from the cathode in the electrolyte during long-term operation, it is possible to improve the deterioration of the lifespan of the fuel cell due to the formation of a short circuit.

Description

MCFC cathode to reduce nickel melt

The present invention relates to an anode for a molten carbonate fuel cell that reduces nickel dissolution and a method for manufacturing the same, and more particularly, Al ₂ O ₃ , ZrO ₂ , YSZ, YDC through an ALD (atomic layer deposition) method on an existing porous cathode. The present invention relates to a cathode for a molten carbonate fuel cell (MCFC) in which Ni is suppressed from melting into a molten carbonate electrolyte at a high temperature by coating such as, and a method for manufacturing the same.

Molten Carbonate Fuel Cell (MCFC) is an effective device that converts chemical energy of various fuels into electrical energy. A nickel anode, a nickel oxide cathode, a matrix of LiAlO2, and lithium carbonate (Li2CO3) and potassium carbonate (K2CO3) It is generally composed of an electrolyte prepared from a mixed salt of Lithium carbonate and potassium carbonate, which are used as raw materials for electrolyte, have very high melting points, but when mixed and dissolved, they are eutectic at around 500°C. Due to these characteristics, the electrolyte is solid at room temperature, but at the operating temperature of 650° C., carbonate is melted and impregnated in the matrix pores to cause an electrochemical reaction through a three-phase reaction with an electrode in a solid state and a reaction gas in a gaseous state.

Nickel oxide (NiO), which is currently used as a cathode material of a typical MCFC, is dissolved by carbonate used as an electrolyte at normal pressure during long-term operation, causing a serious problem of shortening the life of the battery, and the reaction formula is as follows.

NiO → Ni ^{2 +} + O ^2-

^{Nickel ions (Ni 2 +} ) generated on the cathode side by the above reaction formula are precipitated as metallic nickel by the following formula on the anode side.

Ni ^{2 +} + 2e ^- → metal Ni

The metal nickel formation reaction that occurs on the anode side continues toward the cathode as the dissolution phenomenon of the cathode continues, creating a nickel metal passage between the anode and the cathode, which results in a short circuit between the cathode and the anode, shortening or ending the life of the battery.

In order to solve this problem, it is necessary to prevent the nickel ions from being eluted from the cathode into the molten carbonate electrolyte.

A number of studies have been conducted so far, and they can be broadly classified into two categories.

One of them is to slow the dissolution rate of nickel oxide used in the past. A typical method is to control the carbonate component used as an electrolyte of the MCFC or add a third material such as a basic material to the NiO electrode. Under the normal operating conditions of MCFC, NiO is dissolved in the electrolyte according to the acid dissolution reaction mechanism, so the method to lower the solubility of NiO in the electrolyte is to increase the basicity of the electrolyte. A method of increasing the content of lithium carbonate in eutectic carbonate or replacing it with a eutectic salt of lithium/sodium carbonate, or a method of adding carbonate of alkaline earth metal (magnesium, calcium, strontium, barium) to an electrolyte of lithium/potassium carbonate etc. are presented. In addition, a method of adding an alkaline earth metal oxide such as MgO to the NiO electrode itself is also proposed.

Another method is to develop a substitute for NiO and lower its solubility in carbonate electrolytes. LiFeO _2, but the lithium compounds such as LiMnO _2, LiCoO ₂ mentioned as its substitute material, LiFeO _2, and LiMnO ₂ are studies on these because they are not applicable as a substitute material the cell performance decrease is not performed, LiCoO ₂ has potent It is attracting attention as an alternative material. However _{, in the case of LiCoO 2} , the solubility in carbonate electrolyte is as low as 1/2 that of nickel oxide, but its conductivity is lower than that of conventional NiO, so battery performance is lower than that of conventional electrodes, and the strength during electrode molding is very low. It is very difficult to install in a battery and has the disadvantage of being expensive.

On the other hand, Atomic Layer Deposition (ALD) is a type of chemical vapor deposition on the surface of a substrate. A precursor of a material to be deposited is pulsed into a chamber together with a carrier gas to react with heat or plasma. After the reaction has progressed on all surfaces, the reaction is completed by a self-saturated reaction that is no longer deposited. After that, the residual precursor in the chamber is removed (purge), the reactant (Reactant) is input (Pulse) to make the surface capable of reacting again, and this reactant (Reactant) is also removed (Purge) (Pulse-Purge-) Pulse-Purge) 1 Cycle is configured. Since this cycle is repeated and stacked in units of atoms, a thin film of uniform quality can be obtained on any surface of any shape.

Accordingly, the present inventors tried to develop a new method to prevent the eluting of nickel ions from the cathode into the molten carbonate electrolyte, and as a result, Al ₂ O ₃ , ZrO ₂ , YSZ, YDC, etc. The present invention was completed by confirming that the cathode for a molten carbonate fuel cell (MCFC) manufactured by coating with Ni was suppressed from elution from the cathode in the electrolyte during long-term operation, thereby improving the deterioration of the lifespan of the fuel cell due to the formation of a short circuit. did.

Republic of Korea Patent Publication No. 10-2007-0135793 Republic of Korea Patent Registration No. 10-1274592 Republic of Korea Patent Registration No. 10-0884646

An object of the present invention is to solve the problem that the cathode and the anode are short-circuited to end the cell life when Ni is melted and eluted from the electrolyte during long-term cell operation in the conventional molten carbonate fuel cell, and Ni wire is formed in the electrolyte. It is to provide an anode in which nickel ions are suppressed from eluting into a molten carbonate electrolyte at a high temperature by coating _{Al 2} O ₃ , ZrO ₂ , YSZ, YDC, etc. on the existing porous cathode through ALD method.

Another object of the present invention is _{by coating Al 2} O ₃ , ZrO ₂ , YSZ, YDC, etc. on the existing porous cathode through ALD method to suppress the elution of nickel ions into the molten carbonate electrolyte at high temperature by manufacturing an cathode, To provide a method for improving the deterioration of the lifespan of a fuel cell due to the formation of a short circuit.

In order to achieve the above object, the present invention

a nickel-base electrode formed of nickel particles and having a porous structure due to gaps between the nickel particles; and

A coating layer composed of any one selected from the group consisting _{of Al 2} O ₃ , ZrO ₂ , YSZ and YDC on the surface of the electrode;

The coating layer is characterized in that a thin film composed of any one selected from the group consisting _{of Al 2} O ₃ , ZrO ₂ , YSZ and YDC is deposited on the surface of the electrode by atomic layer deposition (ALD).

A cathode for a molten carbonate fuel cell (MCFC) is provided.

Also, the present invention

i) preparing a nickel-base electrode formed by nickel particles and having a porous structure by gaps between the nickel particles; and

ii) coating the surface of the electrode by depositing a thin film composed of any one selected from the group consisting _{of Al 2} O ₃ , ZrO _{2 , YSZ and YDC by atomic layer deposition (ALD) and coating;}

A method for manufacturing a cathode for a molten carbonate fuel cell (MCFC) is provided.

In addition, the present invention

There is provided a molten carbonate fuel cell (MCFC) including the cathode for the molten carbonate fuel cell (MCFC) according to the present invention.

_{According to the present invention, by coating Al 2} O ₃ , ZrO ₂ , YSZ, YDC, etc. on the porous cathode through an atomic layer deposition (ALD) method, it is possible to suppress the melting of Ni into the molten carbonate electrolyte at a high temperature.

Therefore, when the molten carbonate fuel cell is operated for a long period of time, the elution of Ni from the cathode in the electrolyte is suppressed, so that the deterioration of the lifespan of the fuel cell due to the formation of a short circuit between the cathode and the anode due to the Ni elution can be improved.

In a fuel cell such as MCFC, a reaction can occur only when a reaction gas is introduced into the electrode. Since the ALD method forms a very thin film in the nanometer unit, it does not affect the pores so that the gas flows smoothly. . On the other hand, the Sol-Gel coating or plating method is difficult to obtain the desired performance because the coating film is not uniform or there is a high possibility of defects such as clogging the pores.

In particular, in order to prevent Ni from being dissolved in the electrolyte, the uniformity of the coating on the surface of the electrode has a lot of influence. .

1 is a diagram showing the technical concept of the present invention.
FIG. 2 is a photograph analyzed with a transmission electron microscope (TEM) after coating _{Al 2} O ₃ , ZrO ₂ , and YSZ on a porous cathode by an ALD method in an embodiment of the present invention.
3 is a transmission electron microsco-Energy Dispersive X-ray Spectroscopy (TEM-EDS) line after coating _{ZrO 2} on the porous cathode through the ALD method in an embodiment of the present invention; These are photos and graphs analyzed with
4 is a spectra graph analyzed by X-ray photoelectron spectroscopy (XPS) after coating _{ZrO 2} and YSZ through the ALD method on the porous cathode in an embodiment of the present invention:
(a): when only ZrO2 was coated by ALD; and
(b): ALD coated with YSZ (4Zr1Y cycle).
FIG. 5 is a photograph analyzed with a scanning electron microscope (SEM) of an uncoated cathode and a cathode coated with _{ZrO 2} through an ALD method in an embodiment of the present invention.
6 is a photograph analyzed with a scanning electron microscope (SEM) after coating Ag, Cu, and ZnO on a porous cathode through a Sol-Gel coating method in a comparative example of the present invention.
7 is a photograph analyzed with a scanning electron microscope (SEM) after plating Cu and Ru on a porous cathode in a comparative example of the present invention.
8 is a graph showing the results of evaluating electrode performance using cells using each of the uncoated cathode and the cathode coated with YSZ through the ALD method in an embodiment of the present invention.
9 is a schematic diagram showing a method for evaluating electrode solubility in an embodiment of the present invention.
10 shows an uncoated cathode in an embodiment of the present invention, a cathode coated with YSZ having a thickness of 1.5 nm through the ALD method, and an cathode coated with YSZ having a thickness of 3 nm through the ALD method at a temperature of 600° C. and FIG. It is a graph of the result of performing electrode solubility evaluation up to time 150hr.
11 shows an uncoated cathode in an embodiment of the present invention, an cathode coated with YDC to a thickness of 1.5 nm through the ALD method, and an cathode coated with YDC to a thickness of 3 nm through the ALD method at a temperature of 600° C. and FIG. It is a graph of the result of performing electrode solubility evaluation up to time 150hr.
12 shows an uncoated cathode in an embodiment of the present invention, a cathode coated with YSZ to a thickness of 1.5 nm through the ALD method, and an cathode coated with YSZ to a thickness of 3 nm through the ALD method at a temperature of 650° C. and FIG. It is a graph of the result of performing electrode solubility evaluation up to time 250 hr.

Hereinafter, the present invention will be described in detail. In describing the present invention, detailed descriptions of related known configurations or functions may be omitted.

The terms or words used in the present specification and claims are not limited to a conventional or dictionary meaning, and should be interpreted as meanings and concepts consistent with the technical matters of the present invention.

The embodiments described in this specification and the configurations shown in the drawings are preferred embodiments of the present invention, and do not represent all of the technical spirit of the present invention, so various equivalents and modifications that can replace them at the time of the present application there may be

the present invention

a nickel-base electrode formed of nickel particles and having a porous structure due to gaps between the nickel particles; and

A coating layer composed of any one selected from the group consisting _{of Al 2} O ₃ , ZrO ₂ , YSZ and YDC on the surface of the electrode;

The coating layer is characterized in that a thin film composed of any one selected from the group consisting _{of Al 2} O ₃ , ZrO ₂ , YSZ and YDC is deposited on the surface of the electrode by atomic layer deposition (ALD).

A cathode for a molten carbonate fuel cell (MCFC) is provided.

The coating layer is preferably uniformly deposited on the surface of the cathode.

The coating layer preferably has a thickness of 1 to 100 nm, more preferably 1.5 to 10 nm.

_{The coating of Al 2} O ₃ , ZrO ₂ , YSZ, YDC, etc. on the porous cathode according to the present invention through the ALD method allows the reactive gas to penetrate well into the pores of the cathode to uniformly coat the atomic unit.

_{The coating of Al 2} O ₃ , ZrO ₂ , YSZ, YDC, etc. through the ALD method on the porous cathode according to the present invention can control the ratio of the desired element by controlling the number of cycles of the ALD precursor, so the degree of doping can be precisely controlled It can be controlled, and the performance of the fuel cell can be improved by affecting the reaction area and catalyst activity according to the degree of doping.

_{The cathode coated with Al 2} O ₃ , ZrO ₂ , YSZ, YDC, etc. through the ALD method on the porous cathode according to the present invention can suppress the melting of Ni into the molten carbonate electrolyte at a high temperature.

The ALD surface-coated cathode according to the present invention suppresses the elution of Ni from the cathode in the electrolyte during long-term operation, thereby preventing a decrease in the lifespan of the fuel cell due to the formation of a short circuit between the cathode and the anode due to the Ni elution.

On the other hand, the Sol-Gel coating method is a method of forming a film on the substrate with a uniformly dispersed solution in the Sol-Gel state. In general, when coating (Dip-coating) by immersing a porous electrode or spraying the coating (Spraying) , sol, and gel aggregate so that the inside of the pore does not become 100% uniform and the quality is poor in terms of uniformity, such as being thickly piled up only on the surface. There is a limit to preventing the Ni component of the electrode from being dissolved in the molten carbonate electrolyte. In addition, even in the case of plating, it is difficult to set the plating conditions, and the plating film grows and blocks the porous pores.

In a fuel cell such as MCFC, a reaction can occur only when a reaction gas is introduced into the electrode. ALD forms a very thin film in nanometers, so it does not affect the pores, so gas flows smoothly. Other Sol-Gel coatings or plating methods have a high possibility of defects such as uneven coating or blocking pores, making it difficult to obtain desired performance. In particular, in order to prevent Ni from being dissolved in the electrolyte, the uniformity of the coating on the surface of the electrode has a lot of influence. .

Also, the present invention

i) preparing a nickel-base electrode formed by nickel particles and having a porous structure by gaps between the nickel particles; and

ii) coating the surface of the electrode by depositing a thin film composed of any one selected from the group consisting _{of Al 2} O ₃ , ZrO _{2 , YSZ and YDC by atomic layer deposition (ALD) and coating;}

A method for manufacturing a cathode for a molten carbonate fuel cell (MCFC) is provided.

In the manufacturing method, ALD in step ii) is

a) loading the sample into the reactor chamber and then evacuating the sample;

b) injecting water as a catalyst capable of reacting on the surface in a pulse;

c) purging and removing the remaining water after the reaction is completed again after the injection of water;

d) injecting a precursor of an element desired for deposition with a 1.5 second pulse;

e) purging to remove reactants remaining after the reaction; and

It is preferable to carry out in a method including; f) repeating steps 3 to 5 as one cycle and increasing it to a desired thickness.

In the manufacturing method, in step ii), ALD is thermal atomic layer deposition technology, plasma atomic layer deposition technology, ozone (O3) based atomic layer deposition technology, atmospheric pressure atomic layer deposition technology, open-air atomic layer deposition It is preferable to use any one selected from the group consisting of a technology, and an atomic layer deposition technology by a roll-to-roll method.

In the manufacturing method, the ALD in step ii) may use all of the conventionally known general thermal atomic layer deposition or plasma atomic layer deposition,

more preferably

a reactor chamber defining a reaction space;

a substrate disposed within the reactor chamber;

a plasma generating device disposed within the reactor chamber;

a precursor source in communication with the reaction space through a first inlet; and

Preferably, the atomic layer evaporator includes a purge gas source communicating with the reaction space through a first inlet.

In the manufacturing method, ALD in step ii) is

a') for Al ₂ O ₃ coating,

The precursor is trimethyl aluminum,

The precursor injection temperature is 5 ~ 15 ℃,

The purge time is 20 to 40 seconds,

Al and O2 pulse time is 1 to 3 seconds, respectively,

Plasma time is preferably 2 to 4 seconds,

b') for ZrO ₂ coating,

The precursor is CP zirconium,

The precursor injection temperature is 90 ~ 110 ℃,

The purge time is 20 to 40 seconds,

Zr and O2 pulse times are 1 to 3 seconds respectively,

Plasma time is preferably 2 ~ 4 seconds,

c') for YDC coating,

The precursors are (tris-(i-propylcyclopentadienyl) cerium) for Ce and (tris-(methylcyclopentadienyl)yttrium(III)) for Y,

The reactor temperature is 230 ~ 270 ℃,

The precursor injection temperature is 140 ~ 150 ℃,

The water, Ce and Y pulse times are 0.1 to 1 sec, 1 to 3 sec, and 0.5 to 2 sec, respectively,

The repeated cycle (cycle) is preferably Ce: Y = 6 cycles: 1 cycle,

d') for YSZ coating,

The precursors are (tetrakis(dimethylamino)zirconium(IV)) for Zr and (tris-(methylcyclopentadienyl)yttrium(III)) for Y,

The reactor temperature is 230 ~ 270 ℃,

The precursor injection temperature is 70 ~ 90 ℃,

The water, Zr and Y pulse times are 0.1 to 1 sec, 1 to 3 sec, and 0.5 to 2 sec, respectively,

The repeated cycle (cycle) is preferably Zr: Y = 4 cycles: 1 cycle.

In the ALD coating method according to the present invention, the reactive gas penetrates well into the pores of the cathode, so that the coating can be uniformly performed in units of atoms.

In the ALD coating method according to the present invention, it is possible to control the ratio of a desired element by controlling the number of cycles of the ALD precursor, so it is possible to precisely control the degree of doping. It is possible to improve the performance of the fuel cell.

The ALD coating method according to the present invention can suppress the melting of Ni into the molten carbonate electrolyte at the high temperature of the cathode, and thus, during long-term operation, the deterioration of the lifespan of the fuel cell due to the formation of a short circuit between the cathode and the anode due to Ni elution can be prevented. can

In addition, the present invention provides a molten carbonate fuel cell (MCFC) including the cathode for the molten carbonate fuel cell (MCFC) according to the present invention.

Hereinafter, the present invention will be described in more detail through examples.

These examples are only for illustrating the present invention in more detail, and it is obvious to those skilled in the art that the scope of the present invention is not limited by these examples according to the gist of the present invention. .

< Example 1> ALD surface coating air pole Produce

The cathode used had a pore size of 8 to 10 μm, a porosity of 60 to 70%, and a Ni electrode. It was prepared by tape casting using Ni slurry and then heat treated at about 800 to 1000℃ to prepare a Ni electrode.

ALD coating was performed using an atomic layer evaporator (ALD) as follows.

1) After loading the sample into the reactor chamber, it was vacuumed.

2) Water, which becomes a catalyst capable of reacting on the surface, was injected as a pulse.

3) After the injection of water, the reaction was completed and the remaining water was purged to remove it.

4) A precursor of an element desired for deposition was injected with a pulse of 1.5 seconds.

5) Purging was performed to remove the reactants remaining after the reaction.

6) Processes 3 to 5 were viewed as one cycle and repeated to the desired thickness. On the other hand, in the case of YDC, in order to match the doping ratio, the Ce cycle was repeated 6 cycles and then the Y cycle became 1 cycle.

At this time, ALD process conditions were performed as follows.

a) Al ₂ O ₃ coating

Precursor: Al (trimethyl aluminum),

Equipment: PE-ALD (NCD/Lucida M200-PL) used,

Precursor injection temperature: 10℃,

Purge time: 30 s,

Al, O ₂ pulse time 2 s, 2 s,

Plasma Time: 3 s

b) ZrO ₂ coating

Precursor: Zr (CAU zirconium),

Equipment: using PE-ALD;

Precursor injection temperature: 100℃,

Purge time: 30 s,

Zr, O2 pulse time: 2 s, 2 s,

Plasma time: 3 s;

c) YDC coating

Precursor: Ce (tris-(i-propylcyclopentadienyl) cerium),

Y (tris-(methylcyclopentadienyl)yttrium(III)),

Equipment: Thermal ALD (manufactured by Korea Institute of Industrial Technology),

Reactor temperature: 250℃,

Precursor injection temperature: 145℃,

water, Ce and Y pulse times: 0.4 s, 1.5 s, 1 s,

Purge time: 500 s,

Ce : Y = 6 cycles : 1 cycle to match the YDC ratio

d) YSZ coating

Precursor: Zr (tetrakis(dimethylamino)zirconium(IV)),

Y (tris-(methylcyclopentadienyl)yttrium(III)),

Equipment: using Thermal ALD;

Reactor temperature: 250℃,

Zr precursor temperature: 80°C;

water, Ce and Y pulse times: 0.4 s, 1.5 s, 1 s,

Purge time: 500 s,

Zr : Y = 4 cycles : 1 cycle to match the YDC ratio

< Example 2> Coating observation through transmission electron microscope analysis

In order to observe the coating of the surface-coated cathode through the ALD method in <Example 1>, a transmission electron microscope (TEM) analysis and a transmission electron microsco-Energy Dispersive analysis were performed. X-ray Spectroscopy; TEM-EDS) line analysis was performed.

As a result, as shown in FIGS. 2 and 3 , it was confirmed that they were uniformly deposited on the surface of the cathode through ALD.

Through this, it was found that the coating material and the cathode form an interface to inhibit Ni dissolution.

< Example 3> Coating observation through X-ray photoelectron spectroscopy analysis

In order to observe the coating of the surface-coated cathode through the ALD method in <Example 1>, it was analyzed by X-ray photoelectron spectroscopy (XPS).

As a result, as shown in FIG. 4 , it was possible to control the ratio of a desired element by controlling the number of cycles of the ALD precursor, and it was found that the degree of doping of YSZ, YDC, etc. could be precisely controlled.

It was found that the performance of the fuel cell can be improved by affecting the reaction area and catalyst activity according to the degree of doping.

< Example 4> Coating observation through scanning electron microscope analysis

In order to observe the coating of the surface-coated cathode through the ALD method in <Example 1>, a scanning electron microscope (SEM) was used for analysis.

As a result, as shown in FIG. 5 , it was confirmed that the reactive gas penetrated well into the pores of the cathode by performing ALD, so that the coating was uniformly performed in units of atoms.

In addition, it was confirmed that there was little difference in the morphology of the uncoated electrode and the electrode after being coated with ALD.

< comparative example 1> Observation of comparative coating (Sol-Gel coating)

In order to compare with the ALD coating of <Example 1>, the cathode surface was coated with Ag, Cu, and ZnO through the Sol-Gel coating method, and Sol-Gel-coated cathodes with Ag, Cu, and ZnO, respectively, were scanned. It was analyzed with a microscope (Scanning Electron Microscope; SEM).

As a result, as shown in FIG. 6, when coating (Dip-coating) by immersing a porous electrode or spraying coating (Spraying), the sol and gel aggregate and the inside of the pore does not become 100% uniform, but only on the surface. The quality deteriorated in terms of uniformity, such as thick accumulation.

In addition, in the case of coating with a very dilute sol solution in order not to block the pores, since 100% of the electrode surface is not covered, there is a limit in preventing the Ni component of the electrode from being dissolved in the molten carbonate electrolyte.

Through this, it was found that Sol-Gel coating has a high possibility of defects such as uneven coating or clogging of pores, making it difficult to obtain desired performance.

< comparative example 2> Comparative coating (plating) observation

In order to compare with the ALD coating of <Example 1>, the cathode plated with Cu and Ru, each prepared by plating the surface of the cathode with Cu and Ru, respectively, was analyzed with a scanning electron microscope (SEM).

As a result, as shown in FIG. 7 , it was difficult to set the plating conditions even in the case of plating, but it was observed that the plating film grew and blocked the porous pores.

Through this, it was found that there is a limit to reducing Ni dissolution because the plating film is not uniform or there is a high possibility that defects such as clogging of pores occur, so it is difficult to obtain the desired performance, and the uniformity of the plating film is low.

< Example 5> YSZ Performance evaluation of coated electrodes

In order to evaluate the performance of the cathode coated with the YSZ surface through the ALD method in <Example 1>, a unit cell was manufactured and the performance was evaluated.

Electrode performance evaluation was performed under the following conditions.

unit cell component Value operation temperature 600℃ Anode electrode and current collector Size 5.64 cm ² Material (electrode; current collector) Ni-5 wt%Al; Ni Mole ratio of fuel gas (H ₂ : CO ₂ ) 80:20 Total flow rate 80.5 cc/min Cathode electrode and current collector Size 5.64 cm ² Material (electrode; current collector) YSZ coated Ni; SUS316 Mole ratio of fuel gas (Air : CO ₂ ) 70:30 Total flow rate 214.8 cc/min Electrolyte Li ₂ CO ₃ /K ₂ CO ₃ mole ratio 62:38 Matrix γ-LiAlO ₂ U _f (fuel utilization) 0.1

As a result, as shown in FIG. 8, the open circuit voltage of the cell using the uncoated standard cathode was 1.089 V, and the cell using the YSZ coated cathode was 1.084 V, and both at ^{150 mA/cm 2} The difference in the IR loss of the cell was 0.017 V, confirming that there was no significant effect on the performance due to the YSZ coating.

< Example 6> YSZ / YDC Solubility evaluation of coated electrodes

In order to evaluate the solubility of the YSZ and YSD surface-coated cathodes through the ALD method in <Example 1>, the electrode solubility was evaluated in the following way.

1) Li ₂ CO ₃ : K ₂ CO ₃ = An electrolyte prepared in a ratio of 62:38 mol was placed in a crucible.

2) The electrode was placed on top of the electrolyte with the coated side facing up and placed in the reactor.

3) After heating up to 600°C at a rate of 0.2°C/min, the temperature was set to be maintained at 600°C for 300 hours.

4) When the temperature reached 450℃ during temperature increase _{, 30 cc/min of 30% CO 2} , 70% Air Balance mixed gas was flowed.

5) After reaching the target temperature (600°C, 650°C), the electrolyte was periodically collected.

6) When the collected sample cooled, it was sealed and analyzed by inductively coupled plasma-mass spectroscopy (ICP-MS).

As a result, as shown in FIGS. 10-12 and Table 2-4, it was confirmed that the solubility of Ni decreased as the thickness of the YSZ and YDC coatings increased.

It was found that the coating of YSZ, YDC, etc. suppresses the elution of Ni from the cathode in the electrolyte during long-term operation, thereby improving the reduction in the lifespan of the fuel cell due to the formation of a short circuit.

temperature 600℃ time (hr) Sample 20 40 80 150 Standard 2.85 6.52 9.49 9.85 YSZ 1.5 nm 2.96 6.31 8.27 8.67 YSZ 3 nm 2.56 4.72 6.44 8.28

temperature 600℃ time (hr) Sample 20 40 80 150 Standard 2.85 6.52 9.49 9.85 YDC 1.5 nm 3.13 4.78 5.29 6.63 YDC 3 nm 3.07 4.44 5.07 5.65

temperature 650℃ time (hr) Sample 20 40 80 150 250 Standard 2.32 3.84 4.92 6.92 YSZ 1.5 nm 1.41 3.71 5.21 8.75 YSZ 3 nm 2.29 3.84 5.47 5.29 5.83

As described above, preferred embodiments of the present invention have been disclosed in the present specification and drawings, and although specific terms are used, these are only used in a general sense to easily explain the technical content of the present invention and help the understanding of the present invention. , it is not intended to limit the scope of the present invention.

It will be apparent to those of ordinary skill in the art to which the present invention pertains that other modifications based on the technical spirit of the present invention can be implemented in addition to the embodiments disclosed herein.

Claims (7)

a nickel-base electrode formed of nickel particles and having a porous structure due to gaps between the nickel particles; and
A coating layer composed of any one selected from the group consisting _{of Al 2} O ₃ , ZrO ₂ and YSZ on the surface of the electrode;
The coating layer is a thin film composed of any one selected from the group consisting _{of Al 2} O ₃ , ZrO ₂ and YSZ by atomic layer deposition (ALD) on the surface of the electrode,
The coating layer is uniformly deposited on the surface of the cathode,
The coating layer is characterized in that the thickness is 1 ~ 100 nm,
Cathode for molten carbonate fuel cell (MCFC).
delete delete i) manufacturing a nickel-base electrode formed by nickel particles and having a porous structure by gaps between the nickel particles; and
ii) coating by depositing a thin film composed of any one selected from the group consisting _{of Al 2} O ₃ , ZrO ₂ and YSZ on the surface of the electrode by atomic layer deposition (ALD) and coating;
The coating layer formed by the coating is uniformly deposited on the surface of the cathode,
The coating layer is characterized in that the thickness is 1 ~ 100 nm,
A method for manufacturing a cathode for a molten carbonate fuel cell (MCFC).
5. The method of claim 4,
Atomic layer deposition is thermal atomic layer deposition technology, plasma atomic layer deposition technology, ozone (O3) based atomic layer deposition technology, atmospheric pressure atomic layer deposition technology, open-air atomic layer deposition technology, and roll-to-roll method A method of manufacturing a cathode for a molten carbonate fuel cell (MCFC), characterized in that it is performed by any one selected from the group consisting of an atomic layer deposition technique by
5. The method of claim 4,
A method of manufacturing a cathode for a molten carbonate fuel cell (MCFC), characterized in that the doping degree is controlled by controlling the ratio of a desired element by controlling the number of cycles of the atomic layer deposition precursor (precursor).
A molten carbonate fuel cell (MCFC) comprising the cathode according to claim 1 .

Images