Solid oxide cell stack

Abstract

A solid oxide cell stack includes a first interconnect and a second interconnect, a solid oxide cell disposed between the first interconnect and the second interconnect, and a porous metal foam between the first interconnect and the solid oxide cell, the porous metal foam includes a carbon nanostructure formed on a surface of the porous metal foam.

Description

Technical Field

[0001] The present disclosure relates to a solid oxide cell stack. Background Art

[0002] Solid oxide fuel cells (SOFC) and solid oxide electrolyzers (SOEC) include cells composed of solid electrolytes with air electrodes, fuel electrodes and oxygen ion conductivity, and the cells may be referred to as solid oxide cells. Solid oxide cells generate electrical energy by electrochemical reactions, or generate hydrogen by electrolyzing water through the reverse reaction of solid oxide fuel cells. Compared with other types of water electrolysis cells or fuel cells (such as phosphoric acid fuel cells (PAFC), alkaline fuel cells (AFC), polymer electrolyte fuel cells (PEMFC), direct methanol fuel cells (DMFC), solid oxide cells have low overvoltage based on low activation polarization, and have high efficiency due to low irreversible losses. In addition, because solid oxide cells can be used not only for hydrogen fuels, but also for carbon fuels or hydrocarbon fuels, solid oxide cells can have a wide range of fuel selection, and because solid oxide cells have high reaction rates in electrodes, solid oxide cells do not require expensive precious metals as electrode catalysts.

[0003] The solid oxide cell may be used as a stack structure in the form of a pair of interconnectors, and in the present disclosure, it is necessary to sufficiently ensure electrical connectivity / structural connectivity between the interconnectors and the solid oxide cell to improve reliability. Summary of the invention

[0004] Technical issues

[0005] One aspect of the present disclosure is to achieve a solid oxide cell stack configured to improve electrical and structural connectivity between an interconnect and solid oxide cells.

[0006] Technical solutions to technical problems

[0007] In order to solve the above problems, according to one aspect of the present disclosure, a solid oxide cell stack includes: a first interconnector and a second interconnector, a solid oxide cell arranged between the first interconnector and the second interconnector, and a porous metal foam between the first interconnector and the solid oxide cell, wherein the porous metal foam includes a carbon nanostructure formed on its surface.

[0008] According to some embodiments of the present disclosure, the carbon nanostructure may include at least one of a carbon nanotube or a carbon nanofiber.

[0009] According to some embodiments of the present disclosure, the carbon nanostructure may be formed on a surface in contact with the solid oxide in the porous metal foam.

[0010] According to some embodiments of the present disclosure, the carbon nanostructure may be formed on a surface opposite to the surface in contact with the solid oxide in the porous metal foam.

[0011] According to some embodiments of the present disclosure, the carbon nanostructure may be formed throughout the interior and surface of the porous metal foam.

[0012] According to some embodiments of the present disclosure, the carbon nanostructure may be disposed on the surface of the porous metal foam in a direction perpendicular to the surface of the porous metal foam.

[0013] According to an example embodiment of the present disclosure, the carbon nanostructure may be disposed on the surface of the porous metal foam in a random direction with respect to the surface of the porous metal foam.

[0014] According to some embodiments of the present disclosure, the porous metal foam may include Ni.

[0015] According to some embodiments of the present disclosure, the porous metal foam may be an elastomer, and the porous metal foam may be pressed by the first interconnector and the solid oxide cell.

[0016] According to some embodiments of the present disclosure, the solid oxide cell may include a fuel electrode and an air electrode and an electrolyte disposed between the fuel electrode and the air electrode, and the fuel electrode may be disposed at the first interconnector side, and the air electrode may be disposed at the second interconnector side.

[0017] According to some embodiments of the present disclosure, when the porous metal foam is referred to as a first porous metal foam, the solid oxide cell stack may further include a second porous metal foam disposed between the second interconnector and the solid oxide cell.

[0018] According to some embodiments of the present disclosure, the second porous metal foam may include a Cu alloy.

[0019] According to some embodiments of the present disclosure, the solid oxide cell stack may further include: a first end plate and a second end plate, wherein the first and second interconnects, the solid oxide cell and the porous metal foam are disposed between the first and second end plates.

[0020] According to some embodiments of the present disclosure, the solid oxide cell stack may have a structure in which the first interconnector, the porous metal foam, the solid oxide cell, and the second interconnector are sequentially and repeatedly formed two or more times in a direction oriented from the first end plate to the second end plate.

[0021] According to some embodiments of the present disclosure, the porous metal foam may further include a protective film formed on a surface of the carbon nanostructure.

[0022] According to some embodiments of the present disclosure, the protective layer may include at least one of B and Al.

[0023] Beneficial technical effects of the present invention

[0024] In the case of a solid oxide cell stack according to some embodiments of the present disclosure, reliability can be improved by ensuring electrical connectivity and structural connectivity between an interconnect and a solid oxide cell, thereby improving performance when the solid oxide cell stack is used as a fuel cell or a water electrolysis cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is an exploded perspective view schematically showing a solid oxide cell stack according to an example embodiment of the present disclosure;

[0026] Figure 2 and Figure 3 is a cross-sectional view of a region of a solid oxide cell stack;

[0027] Figure 4 It is shown in Figure 2 An illustration of an example of pressing a metal foam in a solid oxide battery stack;

[0028] Figures 5 to 8 is a diagram showing an example of a metal foam that can be used in a solid oxide cell stack;

[0029] Fig. 9 is a diagram showing an example of a carbon nanostructure that can be used in a solid oxide cell stack; and

[0030] Fig.10 and Fig.11 is a diagram showing a solid oxide cell stack according to a modified example. DETAILED DESCRIPTION

[0031] Hereinafter, the example embodiments of the present disclosure will be described with reference to specific example embodiments and the accompanying drawings. However, the example embodiments of the present disclosure may be illustrated in many different forms and should not be construed as being limited to the specific embodiments set forth herein. The example embodiments disclosed herein are provided to better explain the present disclosure to those skilled in the art. In the accompanying drawings, the shapes and sizes of the elements may be exaggerated for clarity, and the same reference numerals will always be used to represent the same or similar elements.

[0032] In order to clearly explain the present disclosure in the drawings, contents irrelevant to the description are omitted, the thickness of each component is exaggerated to clearly indicate multiple layers and regions, and the same reference numerals are used to describe components having the same functions within the scope of the same concept. Throughout the specification, unless otherwise specified, when a part "includes" or "contains" a component, this indicates that other components are not excluded and other components may be further included.

[0033] Figure 1 is an exploded perspective view schematically showing a solid oxide cell stack according to an example embodiment of the present disclosure. Figure 2 and Figure 3 is a cross-sectional view of a region of a solid oxide cell stack. Figure 4 It is shown in Figure 2 Illustration of an example of pressing metal foam in a solid oxide battery stack. Figures 5 to 8 is a diagram showing examples of metal foams that may be used in a solid oxide cell stack.

[0034] Reference Figures 1 to 5 According to some example embodiments of the present disclosure, the solid oxide cell stack 100 may include a first interconnect 111, a solid oxide cell 120, and a second interconnect 112 as main components, and a porous metal foam 131 is disposed between the first interconnect 111 and the solid oxide cell 120. In addition, the porous metal foam 131 may include a carbon nanostructure 132 formed on its surface. The carbon nanostructure 132 employed in this example embodiment may use the porous metal foam 131 formed on its surface to improve the electrical connectivity / structural connectivity between the first interconnect 111 and the solid oxide cell 120, thereby improving the performance and durability of the solid oxide cell stack 100. Hereinafter, the components of the solid oxide cell stack 100 are described in detail, and the case where the solid oxide cell stack 100 is used as a fuel cell is mainly described. However, the solid oxide cell stack 100 may also be used as a water electrolysis cell, and in this case, in the fuel electrode 121 and the air electrode 122 of the solid oxide cell 120, a reaction opposite to that of the fuel cell will occur.

[0035] The first interconnect 111 and the second interconnect 112 may be electrically connected to the solid oxide cell 120, and for example, when the solid oxide cell stack 100 includes a stacked structure including a plurality of solid oxide cells 120, the solid oxide cell stack 100 may be disposed between adjacent solid oxide cells 120 so that the solid oxide cells 120 are connected to each other. The first interconnect 111 and the second interconnect 112 may have a flat plate structure, and may also include a flow path and a through hole through which a gas may diffuse. The first interconnect 111 and the second interconnect 112 may include a material having excellent electrical conductivity and low degradation in a high temperature environment. As a specific example, the first interconnect 111 and the second interconnect 112 may include a metal such as stainless steel, nickel, iron, or copper.

[0036] The solid oxide cell 120 may be disposed between the first interconnect 111 and the second interconnect 112 and corresponds to a functional layer of a fuel cell or a water electrolysis cell. Specifically, the solid oxide cell 120 may include a fuel electrode 121 and an air electrode 122 and an electrolyte 123 disposed between the fuel electrode 121 and the air electrode 122. In this case, the fuel electrode 121 may be disposed on a surface of the electrolyte 123 closer to the first interconnect 111, and the air electrode 122 may be in contact with the second interconnect 112. When the solid oxide cell 120 is a fuel cell, for example, water may be generated in the fuel electrode 121 due to a hydrogen oxidation reaction or an oxidation reaction of a carbon compound, and an oxygen ion generation reaction due to oxygen decomposition may occur in the air electrode 122. When the solid oxide cell 120 is a water electrolysis cell, a reaction opposite to that of a fuel cell may occur, for example, hydrogen may be generated by a reduction reaction of water in the fuel electrode 121, and oxygen may be generated in the air electrode 122. In addition, in the case of a fuel cell, a hydrogen decomposition (hydrogen ion generation) reaction may occur in the fuel electrode 121, and water may be generated by combining oxygen ions and hydrogen ions in the air electrode 122. In the case of a water electrolysis cell, a water decomposition (hydrogen and oxygen ion generation) reaction may occur in the fuel electrode 121, and oxygen may be generated in the air electrode 122. In addition, in the electrolyte 123, ions may move to the fuel electrode 121 or the air electrode 122.

[0037] The fuel electrode 121, the electrolyte 123 and the air electrode 122 may include a solid oxide. Specifically, in the case of the fuel electrode 121, a metal ceramic layer may be included, the metal ceramic layer including a metal-containing phase and a ceramic phase. Here, the metal-containing phase may include a metal catalyst (such as nickel (Ni), cobalt (Co), copper (Cu) or their alloys) acting as an electronic conductor. The metal catalyst may be in a metallic state or an oxide state. In the case where the fuel electrode 121 includes a ceramic phase, the fuel electrode 121 may include gadolinium oxide-doped ceria (GDC), samarium-doped ceria (SDC), yttrium oxide-doped ceria (YDC), scandium oxide-stabilized zirconia (SSZ), yttria ceria scandium oxide-stabilized zirconia (YbCSSZ).

[0038] The electrolyte 123 may include stabilized zirconia. Specifically, the electrolyte 123 may include scandia stabilized zirconia (SSZ), yttria stabilized zirconia (YSZ), scandia ceria stabilized zirconia (SCSZ), scandia ceria yttria stabilized zirconia (SCYSZ), and scandia ceria yttria stabilized zirconia (SCYbSZ).

[0039] The air electrode 122 may include a conductive material including a conductive perovskite material such as lanthanum strontium manganese (LSM). Other conductive perovskites may also be used, for example, lanthanum strontium cobalt (LSC), lanthanum strontium cobalt manganese (LSCM), lanthanum strontium cobalt ferrite (LSCF), lanthanum strontium ferrite (LSF), and other conductive perovskites such as La 0.85 Sr 0.15 Cr 0.9 Ni 0.1 O3 (LSCN) or Pt metal. In some embodiments, the air electrode 122 may include a mixture of a conductive material and an ion conductive ceramic material. For example, the air electrode 122 may include about 10 wt % to about 90 wt % of a conductive material (e.g., LSM, etc.) and about 10 wt % to about 90 wt % of an ion conductive material. Here, the ion conductive material may include a zirconia-based material and / or a ceria-based material.

[0040] In addition, Figure 2 In the exemplary embodiment of FIG. 1 , a portion of the solid oxide cell 120 and the porous metal foam 131 are exposed to the outside, but a sealing structure may be added to protect the solid oxide cell 120 and the porous metal foam 131 and prevent gas leakage. Figure 3As shown, a sealing portion 140 covering the side surface of the solid oxide cell 120 and the side surface of the porous metal foam 131 may also be provided. The sealing portion 140 may include a glass-based material, and in this case, the structure of the sealing portion may be densified at high temperature to prevent liquid or gas leakage. The sealing portion 140 may also include a frame and a gasket structure. In addition, according to some example embodiments, an additional sealing portion for sealing the first interconnect 111 and the second interconnect 112 may also be provided.

[0041] The porous metal foam 131 is disposed between the first interconnect 111 and the solid oxide cell 120, and includes a carbon nanostructure 132 formed on the surface of the porous metal foam 131. The porous metal foam 131 may be, for example, a foam-type metal body structure or a sponge structure wound with a metal wire. As a more specific example, considering that the fuel electrode 121 may have a reducing atmosphere when the solid oxide cell 120 is driven, the porous metal foam 131 may be in the form of Ni foam including Ni. Figure 4 As shown, the porous metal foam 131 may be an elastomer and may be pressed by the first interconnector 111 and the solid oxide cell 120. Because the porous metal foam 131 may include pores H therein, the first interconnector 111 and the solid oxide cell 120 may be electrically connected to each other without interfering with the flow of fuel.

[0042] The carbon nanostructure 132 formed on the surface of the porous metal foam 131 may include at least one of a carbon nanotube and a carbon nanofiber. For example, the carbon nanostructure 132 may have a diameter of several nm to several tens of nm and a length of several μm to several mm. As described, the carbon nanostructure 132 may be formed on the surface S1 of the porous metal foam 131 that contacts the solid oxide 120 or the fuel electrode (121) of the solid oxide (120) (the importance of connectivity at the surface S1 that contacts the solid oxide 120 may be taken into consideration). Figure 5 In FIG. 1 , the shaded area at the surface S1 of the solid oxide 120 in contact with the fuel electrode 121 indicates the area where the carbon nanostructure 132 is formed. Figure 7 As shown, the carbon nanostructure 132 may also be formed on a surface S2 (contacting the first interconnector 111) of the porous metal foam 131 opposite to the surface S1. Figure 8 As shown, the carbon nanostructure 132 may be formed throughout the interior and on the surface of the porous metal foam 131 .

[0043] Reference Figure 5In the enlarged area of ​​the surface S1 in FIG. 1 , the carbon nanostructure 132 may be arranged vertically relative to the surface of the porous metal foam 131. The vertical arrangement method may be achieved by growing the carbon nanostructure 132 on the surface of the porous metal foam 131. Here, the growth of the carbon nanostructure 132 may be formed by a method such as chemical vapor deposition or thermal vapor deposition. In addition, as another example, Figure 6 As shown, the carbon nanostructure 132 may be arranged in a form tilted in a random direction with respect to the surface of the porous metal foam 131. The randomly arranged configuration may be achieved by attaching the previously prepared carbon nanostructure 132 to the surface of the porous metal foam 131.

[0044] As in this example embodiment, when the porous metal foam 131 having the carbon nanostructure 132 is disposed between the first interconnect 111 and the solid oxide cell 120, the electrical characteristics and structural stability of the solid oxide cell stack 100 can be improved. When the solid oxide cell stack 100 is driven, the deformation of the solid oxide cell stack 100 due to vibration may reduce the connectivity between the first interconnect 111 and the solid oxide cell 120, but even in such an environment, the porous metal foam 131 can maintain the connectivity between the first interconnect 111 and the solid oxide cell 120, and the porous metal foam 131 can include a plurality of pores H, so that fuel and the like can pass through the porous metal foam 131. For this reason, as described above, the porous metal foam 131 can have elasticity. In addition, because the carbon nanostructure 132 is formed on the surface of the porous metal foam 131, the resistance between the first interconnect 111 and the solid oxide cell 120 can be further reduced. In addition, the carbon nanostructure 132 can be oriented in various directions, which can further improve resistance to mechanical deformation or anti-contamination.

[0045] In addition, if Fig. 9 As shown, the porous metal foam 131 may further include a protective film 133 formed on the surface of the carbon nanostructure 132. The protective film 133 may perform the function of protecting the carbon nanostructure 132 and preventing oxidation thereof, and may include, for example, at least one of B and Al. In this case, the protective layer 133 may be formed using a metal body of B or Al, an oxide of B or Al, or a combination thereof.

[0046] Will refer to Fig.10 and Fig.11 Describe the modified example. First, Fig.10In the case of, in this example embodiment, the porous metal foam 132 is additionally disposed at the second interconnector 112. In other words, the second porous metal foam 132 is also disposed between the second interconnector 112 and the solid oxide cell 120, and in this case, the first porous metal foam 131 disposed on the side of the first interconnector 111 may be referred to as the first porous metal foam 131. The electrical connectivity and durability between the solid oxide cell 120 and the second interconnector 112 may be improved by further including the second porous metal foam 132. The second porous metal foam 132 may be driven in an oxidizing atmosphere, and in consideration of the driving of the second porous metal foam 132, may be formed using a material including a Cu alloy (e.g., a Cu-Mn alloy).

[0047] Next, Fig.11 The exemplary embodiment of further includes a first end plate 151 and a second end plate 152, and the first interconnector 111 and the second interconnector 112, the solid oxide cell 120 and the porous metal foam 131 may be disposed between the first end plate 151 and the second end plate 152. This case may have a structure in which the first interconnector 111, the porous metal foam 131, the solid oxide cell 120 and the second interconnector 112 are sequentially and repeatedly formed two or more times in a direction oriented from the first end plate 151 to the second end plate 152 (i.e., a direction facing upward relative to the drawing). Therefore, a plurality of solid oxide cells 120 may be connected in series to each other to improve their output, so that the water electrolysis cell can provide a larger amount of hydrogen generation, and the fuel cell can obtain electricity with a higher voltage. The first end plate 151 and the second end plate 152 may include a metal having a high melting point so as not to melt or soften even when the solid oxide cell 120 is driven at a high temperature, and may have a flat structure of the metal. For example, the first end plate 151 and the second end plate 152 may include a material such as a nickel-based material, an iron-based material or a stainless steel-based material. Furthermore, when the operating temperature of the solid oxide cell stack 100 is relatively low (eg, as low as 800° C. or less), copper or a copper alloy having good electrical conductivity may be used.

[0048] The present disclosure is not limited to the above-mentioned exemplary embodiments and the accompanying drawings, but is limited by the appended claims. Therefore, without departing from the scope of the present disclosure defined by the appended claims, a person of ordinary skill in the art may make various substitutions, modifications or changes, and these substitutions, modifications or changes should be interpreted as being included in the scope of the present disclosure.

Claims

1. A solid oxide battery stack, comprising: a first interconnect and a second interconnect; a solid oxide cell disposed between the first interconnect and the second interconnect; as well as a porous metal foam located between the first interconnect and the solid oxide cell, Wherein, the porous metal foam includes a carbon nanostructure located on the surface of the porous metal foam.

2. The solid oxide battery stack according to claim 1, wherein: The carbon nanostructure includes at least one of carbon nanotubes or carbon nanofibers.

3. The solid oxide battery stack according to claim 1, wherein: The porous metal foam includes the carbon nanostructure on a surface of the porous metal foam in contact with the solid oxide.

4. The solid oxide battery stack according to claim 3, wherein: The porous metal foam includes the carbon nanostructures on the surface of the porous metal foam opposite the surface contacting the solid oxide.

5. The solid oxide battery stack according to claim 4, wherein: The porous metal foam includes the carbon nanostructure located throughout the interior and on the surface of the porous metal foam.

6. The solid oxide battery stack according to claim 1, wherein: The carbon nanostructures are disposed perpendicular to the surface of the porous metal foam.

7. The solid oxide battery stack according to claim 1, wherein: The carbon nanostructures are arranged in random orientations relative to the surface of the porous metal foam.

8. The solid oxide battery stack according to claim 1, wherein: The porous metal foam includes Ni.

9. The solid oxide battery stack according to claim 1, wherein: The porous metal foam is an elastomer, and the porous metal foam is compressed by the first interconnect and the solid oxide cell.

10. The solid oxide battery stack according to claim 1, wherein: The solid oxide cell includes a fuel electrode and an air electrode and an electrolyte disposed between the fuel electrode and the air electrode, and the fuel electrode is disposed on a surface of the electrolyte closer to the first interconnector, and the air electrode is disposed at the second interconnector side.

11. The solid oxide battery stack according to claim 10, further comprising: When the porous metal foam is referred to as a first porous metal foam, a second porous metal foam is disposed between the second interconnect and the solid oxide cell.

12. The solid oxide battery stack according to claim 11, wherein: The second porous metal foam includes a Cu alloy.

13. The solid oxide battery stack according to claim 1, further comprising: a first end plate and a second end plate, Wherein, the first interconnector and the second interconnector, the solid oxide cell and the porous metal foam are arranged between the first end plate and the second end plate.

14. The solid oxide battery stack according to claim 13, wherein: The solid oxide cell stack has a structure in which the first interconnector, the porous metal foam, the solid oxide cells, and the second interconnector are sequentially and repeatedly formed two or more times in a direction oriented from the first end plate to the second end plate.

15. The solid oxide battery stack according to claim 1, wherein: The porous metal foam further includes a protective film disposed on a surface of the carbon nanostructure.

16. The solid oxide battery stack according to claim 15, wherein: The protective layer includes at least one of B and Al.

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