Solid oxide battery

Abstract

A solid oxide battery includes a fuel electrode, an air electrode, and an electrolyte disposed between the fuel electrode and the air electrode. The fuel electrode includes a plurality of hole arrays arranged in a first direction. One of the plurality of hole arrays includes a plurality of holes arranged in the second direction. The first direction refers to a thickness direction of the electrolyte, and the second direction refers to a direction perpendicular to the first direction.

Description

Technical Field

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

[0002] Solid oxide fuel cells (SOFCs) and solid oxide electrolysis cells (SOECs) include cells comprising an air electrode, a fuel electrode, and a solid electrolyte having oxygen ion conductivity, and herein, the cells may be referred to as solid oxide cells. Solid oxide cells generate electric power through an electrochemical reaction or electrolyze water through the reverse reaction of a solid oxide fuel cell to generate hydrogen. Compared with other types of fuel cells or water electrolyzers (such as phosphoric acid fuel cells (PAFCs), alkaline fuel cells (AFCs), polymer electrolyte membrane fuel cells (PEMFCs), and direct methanol fuel cells (DMFCs)), solid oxide cells have a low overvoltage based on low activation polarization and have fewer irreversible losses, thus having high efficiency. In addition, since solid oxide cells can use fuels such as carbon or hydrocarbons as well as hydrogen, they have a wide range of fuel options, and solid oxide cells do not require expensive noble metals as electrode catalysts due to their high reaction rate in the electrodes.

[0003] Solid oxide cells generally have a structure in which an electrolyte is disposed between electrode layers, and reactions that function as a cell occur in the electrode layers. To enable the reactions to occur effectively in the electrode layers, gases must be able to pass through them easily, and for this purpose, a technique of forming the electrode layers into randomly shaped porous bodies is known. Summary of the Invention

[0004] Technical Problem Exemplary embodiments provide a highly reactive solid oxide cell by providing a smooth gas flow.

[0005] Technical Solution According to an aspect of the present disclosure, a solid oxide cell includes: a fuel electrode; an air electrode; and an electrolyte disposed between the fuel electrode and the air electrode. The fuel electrode includes a plurality of hole arrays arranged in a first direction. One of the plurality of hole arrays includes a plurality of holes arranged in a second direction. The first direction refers to the thickness direction of the electrolyte, and the second direction refers to a direction perpendicular to the first direction.

[0006] In one of the plurality of hole arrays, the plurality of holes may also be arranged in a third direction to form a grid structure, and the third direction refers to a direction perpendicular to the first direction and the second direction.

[0007] In one of the plurality of hole arrays, the plurality of holes may be arranged at substantially the same level with respect to the first direction.

[0008] The plurality of holes may include holes having a shape in which a width in the second direction or the third direction narrows toward the electrolyte in the first direction, the third direction being a direction perpendicular to the first direction and the second direction.

[0009] The plurality of holes may include holes having a shape in which a maximum length in the second direction and a maximum length in the third direction are substantially the same, the third direction being a direction perpendicular to the first direction and the second direction.

[0010] The plurality of holes may include hemispherical holes.

[0011] The plurality of holes may include first-line holes having a shape in which a maximum length in the third direction is more than twice a maximum length in the second direction, the third direction being a direction perpendicular to the first direction and the second direction.

[0012] In one of the plurality of arrays, the first-line holes may be provided in plurality, and the plurality of first-line holes are regularly arranged in the second direction.

[0013] In one of the plurality of arrays, the plurality of holes may include second-line holes having a shape in which a maximum length in the second direction is more than twice a maximum length in the third direction.

[0014] The second-line holes may be provided in plurality, and the plurality of second-line holes are regularly arranged in the third direction.

[0015] The first-line holes and the second-line holes may cross each other.

[0016] The fuel electrode may include protrusions partially provided in the plurality of holes.

[0017] The protrusions may overlap some of the plurality of holes in the first direction.

[0018] When a distance in the first direction between adjacent hole arrays in the plurality of hole arrays is t, and a maximum length of the holes in the second direction is d, d may be greater than t.

[0019] d may be equal to more than twice t.

[0020] The plurality of hole arrays may be three or more hole arrays and are regularly arranged in the first direction.

[0021] In the plurality of hole arrays, a hole array closest to the electrolyte in the first direction may be spaced apart from the electrolyte in the first direction.

[0022] Among the plurality of pore arrays, the pore array that is farthest from the electrolyte in the first direction may be embedded in the fuel electrode.

[0023] Among the plurality of pore arrays, the pore array that is farthest from the electrolyte in the first direction may be exposed to the surface of the fuel electrode.

[0024] According to an aspect of the present disclosure, a solid oxide cell includes: a fuel electrode; an air electrode; and an electrolyte disposed between the fuel electrode and the air electrode. The fuel electrode includes pore arrays embedded in the fuel electrode and spaced apart from each outer surface of the fuel electrode.

[0025] The pore arrays may include pores having a shape with a width narrowing toward the electrolyte.

[0026] The pore arrays may include pores spaced apart from each other in a first horizontal direction and a second horizontal direction of the fuel electrode such that the pores have a grid structure.

[0027] The pore arrays may include pores spaced apart from each other in a first horizontal direction of the fuel electrode.

[0028] One of the pores may have a linear shape extending in a second horizontal direction of the fuel electrode that intersects the first horizontal direction.

[0029] One of the pores may have a line portion and a connecting portion, the line portion extending in a second horizontal direction of the fuel electrode that intersects the first horizontal direction, and the connecting portion connecting the line portions to each other and having a width greater than the width of the line portion.

[0030] The pore arrays may include a first pore and a second pore, the first pore having a linear shape extending in a first horizontal direction of the fuel electrode, and the second pore having a linear shape extending in a second horizontal direction and intersecting the first pore.

[0031] Advantageous Effects The solid oxide cell according to an example of the present exemplary embodiment may provide a smooth gas flow and thus has excellent reactivity. Therefore, when the solid oxide cell is used as a fuel cell or an electrolytic cell for water electrolysis, the performance can be improved. Brief Description of the Drawings

[0032] Figure 1 is a perspective view schematically showing a solid oxide cell according to an exemplary embodiment in the present disclosure; Figure 2 is a cross-sectional view schematically showing a region of the solid oxide cell; Figure 3is a cross-sectional view schematically showing a region of a solid oxide cell; Figure 4 is an enlarged view of a region of a fuel electrode; Figure 5 is an enlarged view of a region of an electrolyte; Figure 6 is an enlarged view of a region of an air electrode; Figure 7 is a cross-sectional view schematically showing a region of a solid oxide cell according to a variant example; Figures 8 to 11 is a cross-sectional view schematically showing regions of a solid oxide cell according to a variant example, respectively; Figures 12 to 14 schematically shows an example of a method of manufacturing a solid oxide cell; and Figure 15 and Figure 16 schematically shows another example of a method of manufacturing a solid oxide cell. Detailed Description

[0033] Hereinafter, exemplary embodiments of the inventive concept will be described in detail with reference to the accompanying drawings. However, the inventive concept may be illustrated in many different forms and should not be construed as limited to the specific exemplary embodiments set forth herein. Rather, these exemplary embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the inventive concept to those skilled in the art. In the drawings, for clarity, the shapes and sizes of elements may be exaggerated, and the same reference numerals will always be used to denote the same or similar elements.

[0034] To clarify this exemplary embodiment, parts irrelevant to the description are omitted, and like reference numerals denote like elements throughout the specification, and in the drawings, for clarity, the thicknesses of layers, films, panels, regions, etc. are exaggerated. Further, in the drawings, although they are shown in different drawings, like reference numerals denote like elements. Throughout the specification, unless explicitly stated to the contrary, the word "comprising" and its variations such as "comprises" or "containing" will be understood to imply the inclusion of the stated elements but not the exclusion of any other elements.

[0035] Figure 1 is a perspective view schematically showing a solid oxide cell according to an exemplary embodiment in the present disclosure. Figure 2 and Figure 3 is a cross-sectional view schematically showing a region of a solid oxide cell. Figures 4 to 6 are enlarged views of a region of a fuel electrode, a region of an electrolyte, and a region of an air electrode, respectively.

[0036] Refer to Figures 1 to 3, according to an exemplary embodiment of the present disclosure, the solid oxide battery 100 includes a fuel electrode 110, an air electrode 130, and an electrolyte 120 disposed therebetween as main components. Here, the fuel electrode 110 includes hole arrays A1 to A4, in which a plurality of holes V1 are arranged in a direction perpendicular to the first direction D1, and the first direction D1 is the thickness direction of the electrolyte 120. In the fuel electrode 110, a plurality of hole arrays A1 to A4 are provided and the plurality of hole arrays A1 to A4 are arranged in the first direction D1. The regularly arranged holes V1 in the fuel electrode 110 can be used as channels through which gas can flow in and out. Therefore, the reactivity inside the solid oxide battery 100 can be improved. That is, the structure of the holes V1 can promote the lateral flow of gas in the fuel electrode 110. In particular, when the solid oxide battery 100 is used as a solid oxide electrolysis cell (SOEC), the holes V1 can promote the smooth flow of vapor, thereby contributing to the improvement of characteristics.

[0037] Hereinafter, the components of the solid oxide battery 100 will be described in detail. The solid oxide battery 100 can be used as both a fuel cell and a water electrolysis cell. In the case of the water electrolysis cell mode, reactions opposite to those in the case of the fuel cell may occur in the fuel electrode 110 and the air electrode 130 of the solid oxide battery 120. Specifically, when the solid oxide battery 100 is a fuel cell, for example, in the fuel electrode 110, water may be generated due to the oxidation of hydrogen or the oxidation reaction of a carbon compound, and in the air electrode 130, an oxygen ion generation reaction may occur due to the decomposition of oxygen. When the solid oxide battery 100 is a water electrolysis cell, the opposite reaction may occur. For example, hydrogen can be generated according to the reduction reaction of water in the fuel electrode 110, and oxygen can be generated in the air electrode 130. As another example, in the case of a fuel cell, a hydrogen decomposition (hydrogen ion generation) reaction may occur in the fuel electrode 110, and oxygen and hydrogen ions can combine to generate water in the air electrode 130. In the case of a water electrolysis cell, the decomposition of water (generation of hydrogen and oxygen ions) may occur in the fuel electrode 110, and oxygen can be generated in the air electrode 130. In addition, in the electrolyte 120, ions can move to the fuel electrode 110 or the air electrode 130.

[0038] Referring to the materials constituting the fuel electrode 110, the electrolyte 120, and the air electrode 130, first, as Figure 4 shown, the fuel electrode 110 may include an electronic conductor 111 and an ionic conductor 112, and each of the electronic conductor 111 and the ionic conductor 112 may be a sintered body of particles. The electronic conductor 111 can perform a conductive function and a catalytic function, and may include, for example, Ni-based metal, Co-based metal, or Cu-based metal, or lanthanum chromate-based (La 1-x Sr xCrO3, where 0 ≤ 0 < 1), materials, etc. The ion conductor 112 may include yttria-stabilized zirconia (YSZ)-based materials, cerium dioxide (CeO2)-based materials, bismuth oxide (Bi2O3)-based materials, lanthanum gallate (LaGaO3)-based materials, etc. Additionally, the fuel electrode 110 may be a porous body including random holes H1 with random shapes and arrangements, and the random holes H1 are different from the regularly arranged holes V1. In the present exemplary embodiment, the flow of gas in the fuel electrode 110 can be further improved and effectively controlled through the regularly arranged holes V1. That is, during the manufacture of the fuel electrode 110, the random holes H1 can be formed by adding a polymer-based pore former and then removing the polymer-based pore former through heat treatment, and the random holes H1 tend to have a high tortuosity and a small diameter. In the case of only using the random holes H1, gases (such as vapors) with a low average migration distance and a low intrinsic diffusion coefficient may be difficult to flow smoothly, and in particular, it may be difficult to obtain a smooth gas flow in the lateral direction (the direction perpendicular to the direction D1), but this problem can be solved by using the hole arrays A1 to A4. Additionally, Figure 3 The dashed lines in are used to distinguish the regions where the multiple hole arrays A1 to A4 are located, but the corresponding regions are not always distinguished in the fuel electrode 110.

[0039] Referring to Figure 5 , the electrolyte 120 may be a sintered body of particles. The electrolyte 120 may be a porous body including random holes H2, and gases, liquids, etc. can flow in and out through the random holes H2. The electrolyte 120 may include an ion conductor 122, and the materials constituting the ion conductor 122 may include, for example, stabilized zirconia. Specifically, the ion conductor 122 may include scandia-stabilized zirconia (SSZ), yttria-stabilized zirconia (YSZ), scandia-ceria-stabilized zirconia (SCSZ), scandia-ceria-yttria-stabilized zirconia (SCYSZ), scandia-ceria-ytterbium-stabilized zirconia (SCYbSZ), etc.

[0040] Referring to Figure 6 , the air electrode 130 may include an electronic conductor 131 and an ion conductor 132, and the electronic conductor 131 and the ion conductor 132 may each be a sintered body of particles. In the air electrode 130, the electronic conductor 131 may include a conductive material, such as a conductive perovskite material (such as lanthanum strontium manganite (LSM)). Other conductive perovskite materials (such as lanthanum strontium cobalt (LSC), lanthanum strontium cobalt manganese (LSCM), lanthanum strontium cobalt ferrite (LSCF), lanthanum strontium ferrite (LSF), La 0.85 Sr 0.15 Cr 0.9 Ni 0.1O3(LSCN)), or a metal such as Pt. The ion conductor 132 may include materials such as yttria-stabilized zirconia (YSZ), cerium dioxide (CeO2), bismuth oxide (Bi2O3), or lanthanum gallate (LaGaO3). The air electrode 130 may include from about 10 wt% to about 90 wt% of the electronic conductor 131 and from about 10 wt% to about 90 wt% of the ion conductor 132. However, according to an exemplary embodiment, the air electrode 130 may not include the ion conductor 132. As shown, the air electrode 130 may be a porous body including random pores H3, through which gases, liquids, etc. may flow in and out.

[0041] In addition, the solid oxide battery 100 according to the present exemplary embodiment may have a fuel electrode support structure in which the electrolyte 120 and the air electrode 130 are supported by the fuel electrode 110. In the case of the fuel electrode-supported solid oxide battery 100, the thickness of the electrolyte 120 is relatively thin, so the resistance to ion movement may be reduced and the power density may be increased, while the fuel electrode 110 is formed relatively thick, so the gas movement distance may be increased. The increase in the gas movement distance in the fuel electrode 110 may reduce the supply uniformity of the reaction gas, especially when the solid oxide battery 100 is used as a water electrolyzer, resulting in different degrees of local electrochemical reactions, which may cause deterioration of the structure of the solid oxide battery 100. Therefore, in the present exemplary embodiment, by arranging the hole arrays A1 to A4 having regularly arranged holes V1 in the fuel electrode 110, the performance deterioration caused by the increase in the gas movement distance in the fuel electrode-supported solid oxide battery 100 may be reduced. However, the solid oxide battery 100 according to the present exemplary embodiment is not only used as a fuel electrode support structure, but may also be used as an electrolyte 120 support structure in which the fuel electrode 110 and the air electrode 130 are supported by the electrolyte 120.

[0042] Refer to Figure 2 and Figure 3Describe the structure of the pores V1 of the fuel electrode 110 in more detail. The plurality of pore arrays A1 to A4 include a plurality of pores V1 arranged in the second direction D2, and the plurality of pore arrays A1 to A4 are arranged in the first direction D1. Here, the first direction D1 refers to the thickness direction of the electrolyte 120, and the second direction D2 and the third direction D3 refer to directions perpendicular to the first direction D1 and perpendicular to each other. As described above, in the present exemplary embodiment, the plurality of pores V1 are arranged in the lateral direction (corresponding to D2) and the thickness direction (corresponding to D1) of the fuel electrode 110. In this case, as shown, the plurality of pores V1 in at least one of the plurality of pore arrays A1 to A4 may be arranged at substantially the same level with respect to the first direction D1. Additionally, the plurality of pores V1 in at least one of the plurality of pore arrays A1 to A4 may be arranged in the third direction D3 to form a grid structure. In the present exemplary embodiment, an example is shown in which all of the plurality of pore arrays A1 to A4 have the above-described structure.

[0043] Regarding the shape of the pores V1, the plurality of pores V1 may include pores whose width in the second direction D2 or the third direction D3 narrows toward the electrolyte 120 in the first direction D1 (that is, upward in the drawing). As a more specific example, the plurality of pores V1 may include pores having a shape in which the maximum length in the second direction D2 is substantially the same as the maximum length in the third direction D3. Thus, the plurality of pores V1 may include hemispherical pores.

[0044] The size and arrangement of the pores V1 can be determined in consideration of the level at which gas flows smoothly within the fuel electrode 110 and the structural stability of the fuel electrode 110 is ensured. For example, in the plurality of pore arrays A1 to A4, when the distance in the first direction D1 between adjacent pore arrays A1 to A4 is t, and the maximum length of the pore V1 in the second direction D2 is d, d may be greater than t. Additionally, d may be more than twice t. By arranging the pore arrays A1 to A4 at an interval t narrower than the size d of the pores V1, the pore density in the fuel electrode 110 can be sufficiently increased, and even in this case, according to the research of the present inventors, the structural stability of the fuel electrode 110 can be maintained. However, if the pores V1 are too large compared to the interval t of the pore arrays A1 to A4, the pores V1 may be very close to each other in the first direction D1 and the structural stability of the fuel electrode 110 may deteriorate. Therefore, taking this into account, d can be set to a level of 10 times or less of t.

[0045] Three or more hole arrays A1 to A4 may be provided, and the three or more hole arrays A1 to A4 are regularly arranged along the first direction D1, so that a sufficient hole density can be ensured in the fuel electrode 110, and the gas can flow more smoothly in the lateral direction. In the present exemplary embodiment, four hole arrays A1 to A4 are provided, and three or five or more hole arrays A1 to A4 may also be provided. Optionally, only two hole arrays A1 to A4 may also be provided. Among the multiple hole arrays A1 to A4, the hole array A1 closest to the electrolyte 120 in the first direction D1 may be spaced apart from the electrolyte 120 in the first direction D1, whereby the structural stability of the electrolyte 120 can be ensured. In addition, in terms of ensuring the hole density of the fuel electrode 110, the holes V1 do not necessarily need to be exposed to the outside of the fuel electrode 110, and as shown, among the multiple hole arrays A1 to A4, the hole array A4 farthest from the electrolyte 120 in the first direction D1 may be embedded in the fuel electrode 110. However, as in Figure 7 In a variant example, the hole array A5 farthest from the electrolyte 120 in the first direction D1 among the multiple hole arrays A1 to A5 may be exposed to the surface of the fuel electrode 110. In this case, the hole array A5 farthest from the electrolyte 120 in the first direction D1 among the multiple hole arrays A1 to A5 may be provided to form a groove structure in the surface of the fuel electrode 110.

[0046] Reference will be made to Figures 8 to 11 Describe the form of holes that can be adopted in a solid oxide battery according to a variant example. First, Figure 8 and Figure 9 are cross-sectional views schematically showing regions of a solid oxide battery according to a variant example, which respectively correspond to the II-II' cross-sectional view and the III-III' cross-sectional view. In the case of this variant example, the multiple holes V2 have a linear shape, and the gas can flow more smoothly in the lateral direction through this linear shape. Specifically, the multiple holes V2 may include first-line holes V2 having a shape in which the maximum length L3 in the third direction D3 is more than twice the maximum length L2 in the second direction D2. In this case, in at least one of the multiple arrays A1 to A4, multiple first-line holes V2 may be provided, and the multiple first-line holes V2 may be regularly arranged along the second direction D2. In Figure 8 , the first-line holes V2 have a uniform length in the second direction D2, but are not limited thereto. That is, the length of the first-line holes V2 in the second direction D2 may be relatively longer and shorter in the region. For example, as in Figure 10 In a variant example, the first-line holes V2 may be implemented in a structure having a short length in the second direction D2 in the region, and in this shape, the holes V1 arranged in columns and rows to form a grid in Figure 3 may be connected to each other.

[0047] Next, inFigure 11 In the case of a modified example, the gas flow path in the lateral direction is further ensured. Specifically, in at least one of the plurality of arrays A1 to A4, in addition to including the first-line holes V2, the plurality of holes V2 and V3 may further include second-line holes V3, and the maximum length of the second-line holes V3 in the second direction D2 is more than twice the maximum length in the third direction D3. Here, a plurality of second-line holes V3 may be provided, and the plurality of second-line holes V3 may be regularly arranged along the third direction D3. In addition, the first-line holes V2 and the second-line holes V3 may cross each other and may contact each other in some regions to form an integral structure.

[0048] Hereinafter, an example of a method for forming the holes V1, V2, and V3 in the fuel electrode 110 will be described. Figures 12 to 14 An example of a method for manufacturing a solid oxide battery (a method using a pore former 201) is schematically shown. First, a plurality of green sheets G1 to G5 are formed using an electrode material for manufacturing a fuel electrode, and the pore former 201 is regularly formed on the surfaces of the plurality of green sheets G1 to G5. In this case, the pore former 201 may not be formed on the uppermost green sheet G5. The pore former 201 may be a polymer-based material and may be formed in the shape and arrangement of the holes V1, V2, and V3 of the above exemplary embodiments. In the prior art, random holes are formed by adding a pore former when manufacturing the green sheets G1 to G5, but in this exemplary embodiment, the pore former 201 is regularly coated on the surfaces of the green sheets G1 to G5. Figure 13 The state in which the green sheets G1 to G5 are laminated is shown, Figure 14 The state in which the holes V1, V2, and V3 are formed by removing the pore former 201 after sintering is shown.

[0049] Figure 15 and Figure 16 Another example of a method for manufacturing a solid oxide battery is schematically shown. In the case of this manufacturing method, a plate 301 having holes H may be used, and recesses 114 for forming holes may be naturally formed in the process of adsorbing and transporting the green sheet G. Therefore, a separate process for forming the holes V1, V2, and V3 may not be required, thereby improving the process efficiency. Specifically, as shown in Figure 15 , the green sheet G is adsorbed through the holes H of the plate 301. After the plate 301 adsorbs the green sheet G, it is moved to a predetermined area and laminated on the predetermined area. In this process, protrusions 113 may be formed in the area of the surface of the green sheet G adsorbed to the plate 301, and recesses 114 may be formed on the opposite side. In this case, in the lamination process, the protrusions 113 on the surface of the green sheet G may be used as an index indicating the position where the green sheet G to be laminated is to be set. Therefore, when using this manufacturing process, a separate index for the lamination process may not be required, and thus the process efficiency may be improved.

[0050] In addition, the concave portions 114 of the green sheet G may remain after sintering to become holes V1, V2, and V3. Further, the height of the protrusions 113 of the green sheet G may be reduced during the lamination process, and depending on the lamination method, the protrusions 113 may be substantially absent after firing. Optionally, the protrusions 113 may remain with a reduced height, and thus, as Figure 16 (an enlarged view of a partial region corresponding to the fuel electrode 110) shows, the fuel electrode 110 may include a plurality of protrusions 113 that partially fill the holes V1, V2, and V3. In this case, the protrusions 113 may overlap some of the plurality of holes V1, V2, and V3 in the first direction D1.

[0051] The solid oxide cell according to the example of the present exemplary embodiment may provide a smooth gas flow and thus have excellent reactivity. Therefore, when the solid oxide cell is used as a fuel cell or an electrolytic cell for water electrolysis, the performance can be improved.

[0052] Although examples of the exemplary embodiments have been shown and described above, it will be readily understood by those skilled in the art that modifications and variations can be made without departing from the scope of the present disclosure defined by the appended claims.

Claims

1. A solid oxide battery, comprising: A fuel electrode; An air electrode; And An electrolyte disposed between the fuel electrode and the air electrode, Wherein, the fuel electrode includes a plurality of hole arrays arranged along a first direction, one of the plurality of hole arrays includes a plurality of holes arranged along a second direction, the first direction refers to the thickness direction of the electrolyte, and the second direction refers to a direction perpendicular to the first direction.

2. The solid oxide battery according to claim 1, wherein In the one hole array of the plurality of hole arrays, the plurality of holes are further arranged along a third direction to form a grid structure, the third direction refers to a direction perpendicular to the first direction and the second direction.

3. The solid oxide battery according to claim 1, wherein, In the one hole array of the plurality of hole arrays, the plurality of holes are arranged on substantially the same level with respect to the first direction.

4. The solid oxide battery according to claim 1, wherein, The plurality of holes include holes having a shape in which the width in the second direction or the third direction narrows toward the electrolyte along the first direction, the third direction refers to a direction perpendicular to the first direction and the second direction.

5. The solid oxide battery according to claim 1, wherein, The plurality of holes include holes having a shape in which the maximum length in the second direction and the maximum length in the third direction are substantially the same, the third direction refers to a direction perpendicular to the first direction and the second direction.

6. The solid oxide cell according to claim 5, wherein, The plurality of holes include hemispherical holes.

7. The solid oxide battery according to claim 1, wherein, The plurality of holes include first-line holes having a shape in which the maximum length in the third direction is more than twice the maximum length in the second direction, the third direction refers to a direction perpendicular to the first direction and the second direction.

8. The solid oxide battery according to claim 7, wherein, In the one hole array of the plurality of arrays, the first-line holes are provided in plurality, and the plurality of first-line holes are regularly arranged along the second direction.

9. The solid oxide battery according to claim 8, wherein, In the one hole array of the plurality of arrays, the plurality of holes include second-line holes having a shape in which the maximum length in the second direction is more than twice the maximum length in the third direction.

10. The solid oxide battery according to claim 9, wherein, The second-line holes are provided in plurality, and the plurality of second-line holes are regularly arranged along the third direction.

11. The solid oxide battery according to claim 9, wherein, The first-line holes and the second-line holes cross each other.

12. The solid oxide battery according to claim 1, wherein, The fuel electrode includes protrusions partially disposed in the plurality of holes.

13. The solid oxide battery according to claim 12, wherein, The protrusions overlap some of the plurality of holes in the first direction.

14. The solid oxide battery according to claim 1, wherein, d is greater than t, where t is the distance in the first direction between adjacent hole arrays of the plurality of hole arrays, and d is the maximum length of the holes in the second direction.

15. The solid oxide battery according to claim 14, wherein, d is equal to more than twice t.

16. The solid oxide battery according to claim 1, wherein, The plurality of hole arrays are three or more hole arrays and are regularly arranged along the first direction.

17. The solid oxide battery according to claim 1, wherein, In the plurality of hole arrays, the hole array closest to the electrolyte in the first direction is spaced apart from the electrolyte in the first direction.

18. The solid oxide battery according to claim 1, wherein, In the plurality of hole arrays, the hole array farthest from the electrolyte in the first direction is embedded in the fuel electrode.

19. The solid oxide battery according to claim 1, wherein, In the plurality of hole arrays, the hole array farthest from the electrolyte in the first direction is exposed to the surface of the fuel electrode.

20. A solid oxide battery, comprising: A fuel electrode; An air electrode; And An electrolyte, disposed between the fuel electrode and the air electrode, wherein the fuel electrode includes a hole array embedded in the fuel electrode and spaced apart from each outer surface of the fuel electrode.

21. The solid oxide battery according to claim 20, wherein, The hole array includes holes having a shape with a width narrowing toward the electrolyte.

22. The solid oxide battery according to claim 20, wherein, The hole array includes holes spaced apart from each other in a first horizontal direction and a second horizontal direction of the fuel electrode such that the holes have a grid structure.

23. The solid oxide battery according to claim 20, wherein, The hole array includes holes spaced apart from each other in a first horizontal direction of the fuel electrode.

24. The solid oxide battery according to claim 23, wherein, One of the holes has a linear shape extending in a second horizontal direction intersecting the first horizontal direction of the fuel electrode.

25. The solid oxide battery according to claim 23, wherein, One of the holes has a line portion and a connecting portion, the line portion extending in a second horizontal direction intersecting the first horizontal direction of the fuel electrode, the connecting portion connecting the line portions to each other and the width of the connecting portion being greater than the width of the line portion.

26. The solid oxide battery according to claim 20, wherein, The hole array includes a first hole and a second hole, the first hole having a linear shape extending in a first horizontal direction of the fuel electrode, the second hole having a linear shape extending in a second horizontal direction and intersecting the first hole.

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