KR102680852B1 - Interconnector and solid oxide fuel cell stack comprising same - Google Patents

Abstract

The present application relates to an interconnector for a solid oxide battery comprising a nickel (Ni)-cobalt (Co) protective layer and a diffusion prevention layer, wherein the diffusion prevention layer is a layer containing a specific element, and a solid oxide including the interconnector. It relates to fuel cell stacks and their manufacturing methods.

Description

Interconnector and fuel cell stack including the interconnector {INTERCONNECTOR AND SOLID OXIDE FUEL CELL STACK COMPRISING SAME}

This application relates to an interconnector, a fuel cell stack including the interconnector, and a method of manufacturing the interconnector and the fuel cell stack.

In general, solid oxide fuel cells are composed of a stack, which is a structure in which multiple electricity generating units consisting of unit cells and interconnectors are stacked.

Because solid oxide fuel cells operate at high temperatures, they have high energy conversion efficiency and can easily use a variety of fuels. However, in the case of ferritic stainless steel, which is widely used as a substrate for interconnectors, chromium components may volatilize at high temperatures. Volatilized chromium components can deteriorate the performance of the air electrode.

To prevent this, a nickel (Ni)-cobalt (Co) protective layer is currently used to prevent volatilization of chromium components. However, due to this, during the operation of a solid oxide fuel cell at high temperatures, nickel (Ni)-cobalt (Co) protective layers are typically used to prevent volatilization of chromium components. A phenomenon of (Ni) diffusion occurred. When nickel diffuses in this way, pores are created in the substrate and a phenomenon in which the dense structure cannot be maintained is observed. If a problem occurs in the shape of the substrate, the performance of the stack may be reduced.

Therefore, a method is required to prevent nickel diffusion in order to secure the performance of the stack and protect the interconnector.

Korean Patent Application Publication No. 2010-0108956

The present application seeks to provide an interconnector including an oxide protective layer that can ensure the reliability of the performance of a solid oxide fuel cell stack, a fuel cell stack including the interconnector, and a method of manufacturing the interconnector and the fuel cell stack. .

In one embodiment of the present invention, a substrate; A nickel-cobalt protective layer provided on at least one side of the substrate; and an anti-diffusion layer provided between the substrate and the nickel-cobalt protective layer, wherein the thickness of the nickel-cobalt protective layer is greater than the thickness of the anti-diffusion layer, and the anti-diffusion layer includes lanthanum (La) and cerium (Ce). ), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm) ), ytterbium (Yb), and ruthenium (Lu).

In another embodiment of the present invention, two or more solid oxide fuel cell units; and a solid oxide fuel cell stack including at least one interconnector according to the present application between the solid oxide fuel cell units.

In another embodiment of the present invention, preparing a substrate; forming an anti-diffusion layer on at least one surface of the substrate; And forming a nickel-cobalt protective layer on a surface opposite to the surface facing the substrate and the diffusion barrier layer, wherein the thickness of the nickel-cobalt protective layer is greater than the thickness of the diffusion barrier layer, and the diffusion barrier layer is LANTA. Numerum (La), Cerium (Ce), Praseodymium (Pr), Neodymium (Nd), Promethium (Pm), Samarium (Sm), Gadolinium (Gd), Terbium (Tb), Dysprosium (Dy), Holmium (Ho), A method of manufacturing an interconnector for a solid oxide battery comprising one or more metals of erbium (Er), thulium (Tm), ytterbium (Yb), and ruthenium (Lu) is provided.

When the interconnector for a solid oxide fuel cell according to the embodiment of the present application is used, the reliability of the performance of the solid oxide fuel cell stack is good.

By using the interconnector for a solid oxide fuel cell according to the embodiment of the present application, nickel diffusion in the nickel-cobalt protective layer can be prevented.

Figure 1 is a diagram schematically showing an existing interconnector.
Figure 2 is a diagram schematically showing an interconnector according to an embodiment of the present invention.
Figure 3 is a diagram schematically showing the electricity generation principle of a solid oxide fuel cell.
Figures 4 and 5 show cross-sectional images of Example 1 and Comparative Example 1.

Hereinafter, this specification will be described in more detail.

In this specification, when a part 'includes' a certain component, this means that it does not exclude other components but may further include other components, unless specifically stated to the contrary.

In this specification, “layer” means covering more than 70% of the area where the layer exists. Preferably it means covering at least 75%, more preferably at least 80%.

In this specification, “thickness” of a layer means the shortest distance from the bottom to the top of the layer.

In this specification, a “solid oxide fuel cell unit” refers to a solid oxide fuel cell that includes an electrolyte layer, an anode (air electrode) located on one side of the electrolyte layer, and a cathode (fuel electrode) located on the other side of the electrolyte layer. it means. In addition, in this specification, the term "fuel cell unit" means a "solid oxide fuel cell unit" unless otherwise stated. The solid oxide fuel cell unit can be manufactured using materials and methods known in the art. Additionally, the shape of the fuel cell is not limited and may be, for example, coin-shaped, flat-shaped, cylindrical, horn-shaped, button-shaped, sheet-shaped or stacked.

In this specification, the term “solid oxide fuel cell stack” refers to a structure in which a plurality of electricity generating units consisting of solid oxide fuel cell units and interconnectors are stacked, and can be simply expressed as a “stack.” .

In this specification, the “interconnector” serves to separate the oxidizer and fuel and electrically connect the anode (air electrode) and the cathode (fuel electrode).

As used herein, “nickel (Ni)-cobalt (Co) protective layer” refers to a nickel-cobalt oxide layer and a protective layer containing a compound represented by the chemical formula Ni _a Co _b O _c . In the above formula, a, b, and c represent the ratio of moles, and can be typically expressed as NiCo ₂ O ₄ .

In this specification, the “diffusion prevention layer” refers to a layer that prevents nickel (Ni) or cobalt (Co) from diffusing into the interconnector during the heat treatment process to form the nickel (Ni)-cobalt (Co) protective layer. it means.

Figure 1 schematically shows an existing interconnector, in which a nickel-cobalt protective layer 102 is formed on one side of a substrate 101. In this specification, the nickel-cobalt protective layer 102 is a protective layer made of a nickel-cobalt oxide layer. As such, in the case of the existing interconnector, when operating a solid oxide fuel cell at high temperature, nickel (Ni) diffuses from the nickel-cobalt protective layer 102 to the substrate 101 to prevent chromium volatilization, causing the substrate ( 101) may be damaged.

In this specification, high temperature when operating a solid oxide fuel cell means a temperature of 600°C or higher.

In one embodiment of the present invention, a substrate; A nickel-cobalt protective layer provided on at least one side of the substrate; and an anti-diffusion layer provided between the substrate and the nickel-cobalt protective layer, wherein the thickness of the nickel-cobalt protective layer is greater than the thickness of the anti-diffusion layer, and the anti-diffusion layer includes lanthanum (La) and cerium (Ce). ), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm) ), ytterbium (Yb), and ruthenium (Lu). An interconnector for a solid oxide battery containing one or more metals is provided.

In one embodiment of the present invention, the nickel-cobalt content of the nickel-cobalt protective layer is 50% by weight to 80% by weight, preferably 60% by weight to 70% by weight, based on the total weight of the nickel-cobalt protective layer. It may be weight percent.

In one embodiment of the present invention, the content of the metal included in the diffusion prevention layer may be 50% by weight to 80% by weight, preferably 60% by weight to 70% by weight, based on the total weight of the diffusion prevention layer. .

In one embodiment of the present invention, the diffusion prevention layer may include 0.1% by weight or less of the oxide of the metal based on the total weight of the diffusion prevention layer.

Figure 2 schematically shows an interconnector according to an embodiment of the present invention, and a diffusion prevention layer 103 is formed between the substrate 101 and the nickel-cobalt protective layer 102.

In this way, when using an interconnector including the diffusion prevention layer, when the solid oxide fuel cell stack operates at a high temperature, diffusion of nickel from the nickel-cobalt protective layer corresponding to the nickel-cobalt oxide layer to the substrate is prevented, thereby forming a solid oxide. The performance of the fuel cell stack is easy to maintain.

In one embodiment of the present invention, the thickness of the nickel-cobalt protective layer may be 3㎛ to 12㎛, preferably 5㎛ to 10㎛. In the above thickness range, it has an area resistivity value of 0.015 Ω _· cm ² or less and is excellent as an anti-chromium volatilization layer. In general, if the area resistivity value is 0.015 Ω _· cm ² or less, it is considered an excellent value, and the smaller the area resistivity value, the better.

In this specification, the area resistivity is determined by the influence of the substrate, nickel-cobalt protective layer, diffusion prevention layer, and chromium oxide layer generated by chromium (Cr) volatilization. That is, in this specification, area resistivity (ASR, unit: Ω _· cm2) is determined by the value expressed in Equation 1 below.

[Equation 1]

ASR = τ _{s ·} l _s + 2 _· τ _{0 ·} l ₀ + 2 _· τ _{c ·} l _c + 2 _· τ _{Cr ·} l _Cr

In equation 1 above, τ _s is the resistivity of the substrate (unit: Ω _· cm), l _s is the thickness of the substrate (unit: cm) _, τ ₀ is the resistivity of the nickel-cobalt protective layer (unit: Ω _· cm), l ₀ is the nickel-cobalt Thickness of protective layer (unit: cm), τ _c is the resistivity of the diffusion barrier layer (unit: Ω _· ㎝), l _c is the thickness of the diffusion barrier layer (unit: ㎝), τ _Cr is the resistivity of the chromium oxide layer (unit: Ω _· ㎝), l _Cr is the chromium oxide layer refers to the thickness (unit: cm). Equation 1 above is written on the premise that a nickel-cobalt protective layer, a diffusion barrier layer, and a chromium oxide layer are formed on both sides of the substrate.

In one embodiment of the present invention, the thickness of the diffusion prevention layer may be 5 nm to 30 nm, preferably 10 nm to 20 nm. When the thickness is within the above range, conductivity is not affected and nickel diffusion in the nickel-cobalt protective layer can be more effectively prevented.

In one embodiment of the present invention, the nickel-cobalt protective layer may include NiCo ₂ O ₄ .

In one embodiment of the present invention, the diffusion prevention layer is lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), gadolinium (Gd), and terbium. It may contain one or more metals among (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and ruthenium (Lu).

In one embodiment of the present invention, the substrate may be a conductive substrate.

In one embodiment of the present invention, the substrate may include ferritic stainless steel. When using the above material, it is low cost, has excellent oxidation resistance, and can have high electrical conductivity.

In one embodiment of the present invention, two or more unit cells; and a solid oxide fuel cell stack including the above-described interconnector provided between the unit cells.

In one embodiment of the present invention, preparing a substrate; forming an anti-diffusion layer on at least one surface of the substrate; And forming a nickel-cobalt protective layer on a surface opposite to the surface facing the substrate and the diffusion barrier layer, wherein the thickness of the nickel-cobalt protective layer is greater than the thickness of the diffusion barrier layer, and the diffusion barrier layer is LANTA. Numerum (La), Cerium (Ce), Praseodymium (Pr), Neodymium (Nd), Promethium (Pm), Samarium (Sm), Gadolinium (Gd), Terbium (Tb), Dysprosium (Dy), Holmium (Ho), A method of manufacturing an interconnector for a solid oxide battery comprising one or more metals of erbium (Er), thulium (Tm), ytterbium (Yb), and ruthenium (Lu) is provided. Additionally, in the above manufacturing method, the description of the above-described substrate, nickel-cobalt protective layer, and diffusion prevention layer can be applied.

In one embodiment of the present invention, forming the nickel-cobalt protective layer includes forming a nickel-cobalt plating layer by electrolytic plating; And it may include the step of heat treating the nickel-cobalt plating layer.

The step of heat treating the nickel-cobalt plating layer means forming a nickel-cobalt oxide layer by oxidizing the nickel-cobalt plating layer at a temperature of 750°C to 770°C for 7 to 9 hours.

In one embodiment of the present invention, the step of forming the diffusion prevention layer may be performed by a physical vapor deposition (PVD) method.

In this specification, except for the interconnector, materials or methods commonly used in the relevant field may be used.

Figure 3 schematically shows the principle of electricity generation in a solid oxide fuel cell. Oxygen ions are generated as air is electrochemically reduced at the air electrode (anode), and the generated oxygen ions are transferred to the fuel electrode (cathode) through the electrolyte layer. do. Fuel such as hydrogen, methanol, butane, etc. is injected into the anode (cathode), and the fuel combines with oxygen ions and is electrochemically oxidized, giving up electrons to produce water. This reaction causes the movement of electrons to the external circuit.

Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art can easily practice it. However, the present invention may be implemented in many different forms and is not limited to the embodiments described herein.

<Manufacturing example: Preparation of substrate>

A ferritic stainless steel (FSS) STS-430 substrate was processed to a size of 2 cm x 2 cm, and then the entire surface was sandblasted using Al ₂ O ₃ particles with a size of #80 mesh. The sandblasted conductive substrate was washed with ethanol and then dried in atmospheric conditions above 90°C to prepare the substrate.

<Example 1: Deposition of diffusion prevention layer>

The substrate of the manufacturing example was transferred into a vacuum chamber, and an RF multi-target (Multi-target RF magnetron) sputtering method was performed using only the cerium (Ce) target provided in the vacuum chamber. Specifically, power was applied for 12000 seconds under a power condition of 100 W, and argon (Ar), a sputter gas, was supplied into the vacuum chamber at a flow rate of 20 sccm under a pressure condition of 5 mTorr. Through this, a diffusion prevention layer (Ce) with a thickness of 7 nm was deposited on both sides of the substrate. Afterwards, electroplating was performed using a plating solution of nickel (Ni) and cobalt (Co) so that the plating ratio of nickel and cobalt was 1:2, thereby forming a nickel-cobalt plating layer with a thickness of 5 μm. Afterwards, an interconnector with a spinel-structured nickel-cobalt protective layer (NiCo ₂ O ₄ ) with a thickness of 7 μm was manufactured by heat treatment at 760°C for 8 hours.

<Comparative Example 1: Non-deposition of diffusion prevention layer>

An interconnector with a nickel-cobalt protective layer (NiCo ₂ O ₄ ) with a thickness of 7 μm was manufactured in the same manner as in Example 1, except that the diffusion prevention layer (Ce) was not formed.

<Experimental Example 1>

The interconnectors of Example 1 and Comparative Example 1 were heat treated at 800°C for 3 hours, and then their cross-sections were photographed using a scanning electron microscope (equipment name: TM3000). The results are shown in Figures 4 and 5 below.

<Experimental Example 2>

After the interconnectors of Example 1 and Comparative Example 1 were heat treated at 800°C for 3 hours, the area resistivity values were measured using a multi-channel multimeter (KEITHLEY-3706A). The results are shown in Table 1 below.

Area resistivity (Ω·cm ² ) Example 1 0.007 Comparative Example 1 (Reference) 0.015

4 and 5, which are the photographic results of Experimental Example 1, it can be seen that in Comparative Example 1, in which only the NiCo ₂ O ₄ protective layer was formed without a diffusion prevention layer, the Ni component of the protective layer diffused and moved from the protective layer to the substrate during the heat treatment process. I was able to confirm. In contrast, in the case of Example 1 in which the diffusion prevention layer was formed, it was confirmed that the Ni component did not diffuse into the protective layer.

Through the area resistivity values of Experimental Example 2, it was confirmed that Example 1 had an excellent area resistivity value because the Ni component did not diffuse into the protective layer.

101: substrate
102: Nickel-cobalt protective layer
103: Anti-diffusion layer

Claims (10)

Board;
A nickel (Ni)-cobalt (Co) protective layer provided on at least one side of the substrate; and
Comprising a diffusion prevention layer provided between the substrate and the nickel-cobalt protective layer,
The thickness of the nickel-cobalt protective layer is greater than the thickness of the diffusion prevention layer,
The diffusion barrier layer includes lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), gadolinium (Gd), terbium (Tb), dysprosium (Dy), Contains one or more metals among holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and ruthenium (Lu),
The nickel-cobalt protective layer includes NiCo ₂ O ₄ ,
The thickness of the nickel-cobalt protective layer is 3㎛ to 12㎛,
An interconnector for a solid oxide battery, wherein the anti-diffusion layer has a thickness of 5 nm to 30 nm. According to paragraph 1,
The interconnector for a solid oxide battery, wherein the nickel-cobalt content of the nickel-cobalt protective layer is 50% by weight to 80% by weight based on the total weight of the nickel-cobalt protective layer. According to paragraph 1,
An interconnector for a solid oxide battery, wherein the content of the metal included in the diffusion prevention layer is 50% by weight to 80% by weight based on the total weight of the diffusion prevention layer. delete delete delete According to paragraph 1,
An interconnector for a solid oxide battery, wherein the substrate is made of ferritic stainless steel. Two or more solid oxide fuel cell units; and
A solid oxide fuel cell stack including at least one solid oxide cell interconnector according to any one of claims 1 to 3 and 7 between the solid oxide fuel cell units. Preparing a substrate;
forming an anti-diffusion layer on at least one surface of the substrate; and
Comprising the step of forming a nickel-cobalt protective layer on a surface opposite to the surface facing the substrate and the diffusion barrier layer,
The thickness of the nickel-cobalt protective layer is greater than the thickness of the diffusion prevention layer,
The diffusion barrier layer includes lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), gadolinium (Gd), terbium (Tb), dysprosium (Dy), Contains one or more metals among holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and ruthenium (Lu),
The nickel-cobalt protective layer includes NiCo ₂ O ₄ ,
The thickness of the nickel-cobalt protective layer is 3㎛ to 12㎛,
A method of manufacturing an interconnector for a solid oxide battery, wherein the thickness of the diffusion prevention layer is 5 nm to 30 nm. According to clause 9,
A method of manufacturing an interconnector for a solid oxide battery in which the step of forming the diffusion prevention layer is performed by a physical vapor deposition (PVD) method.