Solid oxide battery and manufacturing method thereof

Abstract

A solid oxide battery according to an embodiment includes: a fuel electrode and an air electrode facing each other; and an electrolyte electrode provided between the fuel electrode and the air electrode. The fuel electrode is in a plate shape, the edge of the fuel electrode is rounded in the thickness direction of the fuel electrode, and the fuel electrode comprises a central layer and outer layers arranged on the two sides of the central layer. And a first porosity, which is a porosity of the central layer of the fuel electrode, is smaller than a second porosity, which is a porosity of the outer layer of the fuel electrode.

Description

Technical Field

[0001] The present disclosure relates to a solid oxide battery and a method for manufacturing the same. Background Art

[0002] Generally, solid oxide cells (SOCs) include solid oxide electrolysis cells (SOECs) and solid oxide fuel cells (SOFCs) having substantially the same structure.

[0003] A solid oxide electrolyzer (SOEC) is a device that produces hydrogen by electrolyzing water, and can produce green hydrogen by using electricity generated by renewable energy sources such as solar and wind power, and is essential for carbon neutrality and the hydrogen economy. In particular, a solid oxide electrolyzer (SOEC) is an environmentally friendly energy conversion device with high efficiency due to high temperature operation and no carbon emissions.

[0004] In addition, a solid oxide fuel cell (SOFC) is a device that produces electricity by using the reverse reaction of the electrolysis reaction of water, and has several advantages: it has high power generation efficiency because the irreversible loss is small; since various fuels can be used without a reformer, a wide range of fuel selection includes not only hydrogen but also carbon or hydrocarbon-based fuels; the reaction speed at the electrode is fast, so an expensive noble metal catalyst is not required. .

[0005] Electrolytes and electrodes of unit cells used in solid oxide electrolyzers (SOECs) and solid oxide fuel cells (SOFCs) may be formed using solid oxides.

[0006] In particular, a planar solid oxide cell (SOC) may include a fuel electrode, an electrolyte electrode, and an air electrode in a flat shape. In this case, the fuel electrode may be applied as a fuel electrode support that is thicker than the electrolyte electrode and the air electrode and has a wider area than the electrolyte electrode and the air electrode.

[0007] The edges and corners of the fuel electrode, electrolyte electrode, and air electrode of the flat type solid oxide cell have right angle shapes and sharp angle shapes, and thus when a stack is formed by stacking unit cells, the edges and corners may be worn or damaged.

[0008] In addition, when unit cells are stacked, stress and pressure are concentrated on sharp edges and corners due to contact with a sealing material or clamping pressure, and thus the edges and corners may be damaged. Summary of the invention

[0009] Technical issues

[0010] An embodiment is to provide a solid oxide cell and a method of manufacturing the same, which can minimize damage during stack manufacturing by distributing pressure and stress applied to edges and corners.

[0011] However, the problems to be solved by the embodiments can be variously expanded within the scope of the technical ideas included in the embodiments without being limited to the above-mentioned problems.

[0012] Technical Solution

[0013] The solid oxide cell according to the embodiment includes: a fuel electrode and an air electrode facing each other; and an electrolyte electrode disposed between the fuel electrode and the air electrode. The fuel electrode may have a plate shape, an edge of the fuel electrode may be rounded along a thickness direction of the fuel electrode, the fuel electrode may include a central layer and outer layers disposed on both sides of the central layer, and a first porosity as a porosity of the central layer of the fuel electrode may be smaller than a second porosity as a porosity of the outer layer of the fuel electrode.

[0014] A first corner, which is a corner connecting the edges of the fuel electrode, may be rounded in the thickness direction of the fuel electrode.

[0015] The first corner may be rounded on a plane intersecting the thickness direction of the fuel electrode.

[0016] The radius of curvature of the edge of the fuel electrode may range from ¼ of the thickness of the fuel electrode to the thickness of the fuel electrode.

[0017] A second corner of the corners of the electrolyte electrode and a third corner of the corners of the air electrode may be rounded on a plane intersecting the thickness direction of the fuel electrode.

[0018] A radius of curvature of each of the first corner, the second corner, and the third corner on a plane intersecting the thickness direction of the fuel electrode may be in the range of 0.1 mm to 2 mm.

[0019] The fuel electrode may further include an intermediate layer disposed between the central layer and the outer layer and having a third porosity, and the third porosity may be greater than the first porosity and less than the second porosity.

[0020] The length of the intermediate layer may be longer than the length of the outer layer and shorter than the length of the central layer.

[0021] In addition, according to the embodiment, the manufacturing method of the solid oxide cell includes: stacking and pressing a plurality of fuel electrode components, the plurality of fuel electrode components including a central component and outer components arranged on both sides of the central component; stacking an electrolyte component on the fuel electrode component; sintering the plurality of fuel electrode components and the electrolyte component to form a fuel electrode and an electrolyte electrode, so that the edge of the fuel electrode is rounded along the thickness direction of the fuel electrode, and the first porosity is smaller than the second porosity, the first porosity is the porosity of the central layer formed using the central component, and the second porosity is the porosity of the outer layer formed using the outer component; and forming an air electrode on the electrolyte electrode.

[0022] By sintering the plurality of fuel electrode members, the outer members may shrink more than the central member, so that the length of the outer layer formed by sintering the outer members may be shorter than the length of the central layer formed by sintering the central member.

[0023] The step of preparing the plurality of fuel electrode members may include forming a first corner as a corner of the plurality of fuel electrode members to be rounded on a plane intersecting the thickness direction of the fuel electrode.

[0024] The step of stacking the electrolyte members may include forming a second corner, which is a corner of the electrolyte member, to be rounded on a plane intersecting the thickness direction of the fuel electrode.

[0025] The forming of the air electrode may include forming a third corner, which is a corner of the air electrode, to be rounded on a plane intersecting the thickness direction of the fuel electrode.

[0026] The solid oxide cell according to the embodiment includes: a fuel electrode and an air electrode facing each other; and an electrolyte electrode disposed between the fuel electrode and the air electrode. The fuel electrode may have a plate shape, and a central portion of the fuel electrode may be longer than a portion of the fuel electrode closer to the electrolyte electrode than the central portion.

[0027] A first corner, which is a corner connecting edges of the fuel electrode, may be rounded in a thickness direction of the fuel electrode.

[0028] The curvature radius of the fuel electrode may be in the range of 0.1 mm to 2 mm.

[0029] A second corner of the corners of the electrolyte electrode and a third corner of the corners of the air electrode may be rounded on a plane intersecting the thickness direction of the fuel electrode.

[0030] The length of the fuel electrode may decrease in a direction from the central portion of the fuel electrode toward the portion of the fuel electrode closer to the electrolyte electrode than the central portion.

[0031] The porosity of the fuel electrode may increase in a direction from the central portion of the fuel electrode toward the portion of the fuel electrode closer to the electrolyte electrode than the central portion.

[0032] The length of the electrolyte electrode may be greater than the length of the air electrode and less than the length of the fuel electrode.

[0033] Beneficial Effects

[0034] According to an embodiment, a first porosity as a central layer of the fuel electrode is smaller than a second porosity as an outer layer of the fuel electrode, so that edges and corners of the fuel electrode can be rounded along a thickness direction of the fuel electrode.

[0035] Therefore, damage to the fuel electrode during stack manufacturing can be minimized by distributing the pressure and stress applied to the edges and corners of the fuel electrode.

[0036] In addition, by forming the corners of the electrolyte electrode and the air electrode to be rounded, pressure and stress applied to the corners of the electrolyte electrode and the air electrode can be dispersed to minimize damage to the electrolyte electrode and the air electrode during stack manufacturing.

[0037] However, it is apparent that the effects of the embodiment are not limited to the above-described effects, and various extensions can be made within a scope not departing from the spirit and scope of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 is a schematic perspective view of a solid oxide battery according to an embodiment.

[0039] Figure 2 yes Figure 1 Top view of the floor plan.

[0040] Figure 3 yes Figure 2 A cross-sectional view taken along line III-III'.

[0041] Figure 4 yes Figure 3 An enlarged cross-sectional view of portion A in FIG.

[0042] Figure 5 yes Figure 4 A partial enlarged photograph of the central layer and middle layer.

[0043] Figure 6 and Figure 7A description of one step of a method for manufacturing a solid oxide cell according to an embodiment is provided. DETAILED DESCRIPTION

[0044] Hereinafter, with reference to the accompanying drawings, various embodiments of the present invention will be described in detail, so that ordinary technicians can easily practice them in the technical field to which the present invention belongs. The present invention can be embodied in many different forms and is not limited to the embodiments described herein.

[0045] In order to clearly explain the present invention, parts irrelevant to the description have been omitted, and the same reference numerals are used for the same or similar constituent elements throughout the specification.

[0046] In addition, the drawings are only used to facilitate understanding of the embodiments disclosed in this specification. The technical ideas disclosed in this specification are not limited by the drawings, and all changes included in the spirit and technical scope of the present invention should be understood to include equivalent solutions or alternative solutions.

[0047] In addition, since the size and thickness of each component shown in the drawings are arbitrarily indicated for better understanding and convenience of description, the present invention is not necessarily limited thereto. In the drawings, the thickness of layers and regions is exaggerated for clarity. In the drawings, the thickness of layers, films, panels, regions, etc. is exaggerated for ease of description.

[0048] It will be understood that when an element such as a layer, film, region, or substrate is referred to as being "on" another element, it can be directly on the other element or intervening elements may also be present. In contrast, when an element is referred to as being "directly on" another element, there are no intervening elements. Furthermore, throughout the specification, the term "on" a target element will be understood to mean being positioned above or below the target element, and will not necessarily be understood to mean being positioned "on the upper side" based on being opposite to the direction of gravity.

[0049] In addition, unless explicitly described to the contrary, the word “comprise” and variations such as “include” or “comprising”, will be understood to imply the inclusion of stated elements but not the exclusion of any other elements.

[0050] Furthermore, throughout the specification, the phrase “on a plane” means observing a target portion from the top, and the phrase “on a cross section” means observing a cross section formed by vertically cutting the target portion from the side.

[0051] In addition, throughout the specification, when “connected to” is used, this means not only that two or more constituent elements are directly connected, but also that two or more constituent elements are indirectly connected, physically connected, and electrically connected through other constituent elements, or are referred to by different names according to position or function, but are integrated.

[0052] Hereinafter, various embodiments and exemplary modifications will be described in detail with reference to the accompanying drawings.

[0053] Figure 1 is a schematic perspective view of a solid oxide battery according to an embodiment, Figure 2 yes Figure 1 A top view of the Figure 3 yes Figure 2 A cross-sectional view taken along line III-III', and Figure 4 yes Figure 3 An enlarged cross-sectional view of portion A in FIG.

[0054] like Figures 1 to 3 As shown in , the solid oxide cell according to the embodiment includes a fuel electrode 100, an electrolyte layer 200, and an air electrode 300 which are sequentially stacked.

[0055] The size and thickness of the fuel electrode 100 may be greater than the size and thickness of the electrolyte electrode 200 and the air electrode 300. Therefore, the fuel electrode 100 may support the stacked electrolyte electrode 200 and the air electrode 300. In the case of a solid oxide electrolytic cell (SOEC), the fuel electrode 100 may be supported by receiving a reducing atmosphere such as water (H 2 O) fuel gas to produce hydrogen and oxygen ions through electrolysis.

[0056] Since the fuel electrode 100 has a square plate shape, it may have four edges 100 a and a first corner 100 b connecting the four edges 100 a to one another.

[0057] The edge 100 a of the fuel electrode 100 is rounded along the thickness direction Z of the fuel electrode 100 , and the first corner 100 b of the fuel electrode 100 may also be rounded along the thickness direction Z of the fuel electrode 100 .

[0058] Therefore, compared with the case where the edge 100a of the fuel electrode 100 has a straight shape, the area of ​​the edge 100a of the fuel electrode 100 is increased, and the pressure per unit area is reduced. Therefore, the strength can be increased in terms of physical impact by pressure. As described, by distributing the pressure and stress applied to the edge 100a and the first corner 100b of the fuel electrode 100, the damage to the fuel electrode 100 during the manufacture of the stack can be minimized.

[0059] like Figure 3 and Figure 4 As shown in , the fuel electrode 100 may include a central layer 110 , an intermediate layer 130 , and an outer layer 120 which are stacked.

[0060] The central layer 110 is disposed in the center and may have a first shortest length d1. The middle layer 130 includes a first middle layer 131 and a second middle layer 132 disposed opposite to both sides of the central layer 110, respectively, and may have a second shortest length d2. The outer layer 120 includes a first outer layer 121 and a second outer layer 122 disposed opposite to both sides of the middle layer 130, respectively, and may have a third shortest length d3.

[0061] The fuel electrode 100 is a solid oxide having ion conductivity and may include a metal oxide such as yttrium oxide Y 2 O 3 Dissolved in zirconium oxide ZrO 2 Yttria-stabilized zirconia ZrO 2 (YSZ), scandia stabilized zirconia (ScSZ), GDC, and LDC. However, the fuel electrode 100 is not limited thereto and may be made of various materials.

[0062] Figure 5 yes Figure 4 A partial enlarged photograph of the central layer and middle layer.

[0063] like Figure 5 As shown in , the fuel electrode 100 may have a plurality of pores AG used as gas movement paths. The first porosity, which is the porosity of the central layer 110 of the fuel electrode 100, is smaller than the second porosity, which is the porosity of the outer layer 120 of the fuel electrode 100, and the third porosity, which is the porosity of the middle layer 130 of the fuel electrode 100, is larger than the first porosity and smaller than the second porosity. Therefore, in the sintering process, the outer layer 120 having the largest porosity may shrink more than the central layer 110 and the middle layer 130.

[0064] like Figure 4 As shown in , the central layer 110 shrinks a first shrinkage length W1, but the outer layer 120 may shrink a second shrinkage length W2 that is shorter than the first shrinkage length W1. In addition, the intermediate layer 130 may shrink a third shrinkage length W3 that is longer than the first shrinkage length W1 and shorter than the second shrinkage length W2. Therefore, the edge 100a of the fuel electrode 100 may be rounded along the thickness direction Z of the fuel electrode 100.

[0065] In this case, the edge 100a of the fuel electrode 100 may have a curvature radius R of ½ the thickness D of the fuel electrode 100 and may be rounded along the thickness direction Z of the fuel electrode 100. In one example, the curvature radius R of the fuel electrode 100 may be in the range of ¼ the thickness D to the thickness D.

[0066] If the curvature radius R of the fuel electrode 100 is less than 1 / 4 of the thickness D, it may be easily affected by stress in the thickness direction Z, and if the curvature radius R of the fuel electrode 100 is greater than the thickness D, the effect of stress distribution is reduced.

[0067] Thus, the first porosity of the central layer 110 of the fuel electrode 100 is formed to be smaller than the second porosity of the outer layer 120 of the fuel electrode 100 , and thus the edge 100 a and the first corner 100 b of the fuel electrode 100 may be rounded in the thickness direction Z.

[0068] The first corner 100 b of the fuel electrode 100 may be rounded on a plane. Therefore, damage to the fuel electrode 100 during stack manufacturing may be minimized by further distributing pressure and stress applied to the first corner 100 b of the fuel electrode 100 .

[0069] Furthermore, in the case of a solid oxide electrolytic cell (SOEC), the electrolyte electrode 200 may transfer oxygen ions generated from the fuel electrode 100 to the air electrode 300 .

[0070] Since the electrolyte electrode 200 has a square plate shape, it may have four edges 200 a and four second corners 200 b , which are four corners connecting the four edges 200 a to one another.

[0071] The second corner 200 b of the electrolyte electrode 200 may be rounded on a plane. Therefore, damage to the electrolyte electrode 200 during stacking can be minimized by distributing pressure and stress applied to the second corner 200 b of the electrolyte electrode 200 .

[0072] In the case of a solid oxide electrolytic cell (SOEC), the air electrode 300 may generate oxygen by oxidizing oxygen ions transferred from the electrolyte electrode 200 in an oxidizing atmosphere.

[0073] The air electrode 300 may be formed by coating using the following method and then performing sintering at about 1200° C. to about 1300° C.: using lanthanum strontium manganate (La 0.84 Sr 0.16 )MnO 3 ), a dry method (such as electrochemical deposition, sputtering, ion beam, ion implantation, etc.), a wet method (such as tape casting, spraying, dipping, screen printing, doctor blade, etc.). However, the air electrode 300 is not limited thereto and can be made of various materials.

[0074] Since the air electrode 300 has a square plate shape, it may have four edges 300 a and four third corners 300 b connecting the four edges 300 a to one another.

[0075] The third corner 300 b of the air electrode 300 may be rounded on a plane. Therefore, damage to the air electrode during stacking may be minimized by distributing pressure and stress applied to the third corner 300 b of the air electrode 300 .

[0076] The first corner 100b, the second corner 200b, and the third corner 300b may have the same curvature radius r1, r2, and r3 on a plane intersecting the thickness direction of the fuel electrode. Therefore, the damage to the fuel electrode 100, the electrolyte electrode 200, and the air electrode may be further minimized by uniformly distributing the pressure and stress applied to the first corner 100b, the second corner 200b, and the third corner 300b.

[0077] Here, the curvature radius r1 of the first corner 100b, the curvature radius r2 of the second corner 200b, and the curvature radius r3 of the third corner on the plane may be in the range of 0.1 mm to 2 mm.

[0078] If the curvature radii r1, r2 and r3 are less than 0.1 mm, the effect of stress distribution is reduced. If the curvature radii r1, r2 and r3 are greater than 2 mm, the areas of the fuel electrode 100, the electrolyte electrode 200 and the air electrode may be reduced, thereby deteriorating battery performance.

[0079] Next, refer to Figure 6 and Figure 7 as well as Figures 1 to 4 , a method for manufacturing a solid oxide battery according to an embodiment will be described in detail.

[0080] Figure 6 and Figure 7 A description of one step of a method for manufacturing a solid oxide cell according to an embodiment is provided.

[0081] like Figure 6 As shown in , according to the manufacturing method of the solid oxide cell according to the embodiment, a plurality of fuel electrode components 1 having a square plate shape are prepared. The plurality of fuel electrode components 1 may have the same size and thickness. The first corners 100b of the plurality of fuel electrode components 1 may be formed to be rounded on a plane.

[0082] The plurality of fuel electrode members 1 may include a central member 10, an intermediate member 30, and an outer member 20. The central member 10 may have a first porosity. The intermediate member 30 may have a third porosity higher than the first porosity. The outer member 20 may have a second porosity greater than the third porosity.

[0083] Then, a plurality of fuel electrode members 1 are stacked. In this case, a central member 10 may be provided at the center. The intermediate member 30 may include a first intermediate member 31 and a second intermediate member 32 respectively provided opposite to both sides of the central member 10. The outer member 20 may include a first outer member 21 and a second outer member 22 respectively provided opposite to both sides of the intermediate member 30.

[0084] In addition, a plurality of fuel electrode members 1 may be attached to each other by pressing the plurality of fuel electrode members 1 .

[0085] In addition, the electrolyte member 2 is stacked on the fuel electrode member 1. In this case, the second corner of the electrolyte member 2 may be formed to be rounded on the plane.

[0086] In addition, a shrinking process such as sintering a plurality of the fuel electrode members 1 and the electrolyte members 2 may be performed to form the fuel electrode 100 and the electrolyte electrode 200 .

[0087] When sintering a plurality of fuel electrode members 1, the outer member 20 having a large porosity may shrink more than the intermediate member 10 having a small porosity. Therefore, the third shortest length d3 (refer to Figure 3 ) may be shorter than the first shortest length d1 of the central layer 110 formed by sintering the intermediate member 10 .

[0088] In addition, the second shortest length d2 (refer to Figure 3 ) may be shorter than the first shortest length d1 of the central layer 110 and longer than the third shortest length d3 of the outer layer 120 .

[0089] Therefore, the edge 100 a and the first corner 100 b of the fuel electrode 100 may be rounded along the thickness direction Z of the fuel electrode 100 .

[0090] Then, the air electrode 300 is formed on the electrolyte electrode 200. In this case, the third corner 300b of the air electrode 300 may be formed to be rounded on a plane.

[0091] While the invention has been described in conjunction with what are presently considered to be practical embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but rather is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

Claims

1. A solid oxide battery comprising: a fuel electrode and an air electrode, facing each other; as well as an electrolyte electrode disposed between the fuel electrode and the air electrode, Wherein, the fuel electrode has a plate shape, The edge of the fuel electrode is rounded along the thickness direction of the fuel electrode, The fuel electrode includes a central layer and outer layers disposed on both sides of the central layer, and A first porosity which is the porosity of the central layer of the fuel electrode is smaller than a second porosity which is the porosity of the outer layer of the fuel electrode.

2. The solid oxide battery according to claim 1, wherein: A first corner, which is a corner connecting the edges of the fuel electrode, is rounded along the thickness direction of the fuel electrode.

3. The solid oxide battery according to claim 2, wherein: The first corner is rounded on a plane intersecting the thickness direction of the fuel electrode.

4. The solid oxide battery according to claim 3, wherein: The radius of curvature of the edge of the fuel electrode is in a range from ¼ of the thickness of the fuel electrode to the thickness of the fuel electrode.

5. The solid oxide battery according to claim 3, wherein: A second corner of the corners of the electrolyte electrode and a third corner of the corners of the air electrode are rounded on a plane intersecting the thickness direction of the fuel electrode.

6. The solid oxide battery according to claim 5, wherein: A radius of curvature of each of the first corner, the second corner, and the third corner on a plane intersecting the thickness direction of the fuel electrode ranges from 0.1 mm to 2 mm.

7. The solid oxide battery according to claim 1, wherein: The fuel electrode further includes an intermediate layer disposed between the central layer and the outer layer and having a third porosity, and The third porosity is greater than the first porosity and less than the second porosity.

8. The solid oxide battery according to claim 7, wherein: The length of the intermediate layer is longer than the length of the outer layer and shorter than the length of the central layer.

9. A method for manufacturing a solid oxide battery, comprising: preparing a plurality of plate-shaped fuel electrode members including a central member and outer members provided on both sides of the central member; stacking and pressing the plurality of fuel electrode components; stacking an electrolyte member on the fuel electrode member; sintering the plurality of fuel electrode members and the electrolyte member to form a fuel electrode and an electrolyte electrode, so that the edges of the fuel electrode are rounded in a thickness direction of the fuel electrode and a first porosity is smaller than a second porosity, the first porosity being a porosity of a central layer formed using the central member and the second porosity being a porosity of an outer layer formed using the outer member; as well as An air electrode is formed on the electrolyte electrode.

10. The method for manufacturing a solid oxide battery according to claim 9, wherein: By sintering the plurality of fuel electrode components, The outer member shrinks more than the central member, so that the length of the outer layer formed by sintering the outer member is shorter than the length of the central layer formed by sintering the central member.

11. The method for manufacturing a solid oxide battery according to claim 10, wherein: The step of preparing the plurality of fuel electrode components comprises: A first corner as a corner of the plurality of fuel electrode members is formed to be rounded on a plane intersecting the thickness direction of the fuel electrode.

12. The method for manufacturing a solid oxide battery according to claim 11, wherein: The step of stacking the electrolyte components comprises: A second corner, which is a corner of the electrolyte member, is formed to be rounded on a plane intersecting the thickness direction of the fuel electrode.

13. The method for manufacturing a solid oxide battery according to claim 12, wherein: The step of forming the air electrode comprises: A third corner, which is a corner of the air electrode, is formed to be rounded on a plane intersecting the thickness direction of the fuel electrode.

14. A solid oxide battery comprising: a fuel electrode and an air electrode, facing each other; as well as an electrolyte electrode disposed between the fuel electrode and the air electrode, wherein the fuel electrode has a plate shape, and A central portion of the fuel electrode is longer than a portion of the fuel electrode that is closer to the electrolyte electrode than the central portion.

15. The solid oxide battery according to claim 14, wherein: A first corner, which is a corner connecting edges of the fuel electrode, is rounded in a thickness direction of the fuel electrode.

16. The solid oxide battery according to claim 15, wherein: in, The curvature radius of the fuel electrode is in the range of 0.1 mm to 2 mm.

17. The solid oxide battery according to claim 15, wherein: A second corner of the corners of the electrolyte electrode and a third corner of the corners of the air electrode are rounded on a plane intersecting the thickness direction of the fuel electrode.

18. The solid oxide battery according to claim 14, wherein: The length of the fuel electrode decreases in a direction from the central portion of the fuel electrode toward the portion of the fuel electrode closer to the electrolyte electrode than the central portion.

19. The solid oxide battery according to claim 14, wherein: The porosity of the fuel electrode increases in a direction from the central portion of the fuel electrode toward the portion of the fuel electrode closer to the electrolyte electrode than the central portion.

20. The solid oxide battery according to claim 14, wherein: The length of the electrolyte electrode is greater than the length of the air electrode and smaller than the length of the fuel electrode.

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