Solid oxide cell stack

Abstract

A solid oxide cell stack includes: a first end plate having a flow path; the solid oxide battery is arranged on the first end plate; and a second end plate including a lower region disposed on the solid oxide battery and having a first through hole and an upper region disposed on the lower region and having a second through hole. In the second end plate, an inner side wall of the upper region forming the second through hole is inclined such that a width of the second through hole increases in an upward direction.

Description

Technical Field

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

[0002] Solid oxide fuel cell (SOFC) and solid oxide electrolyzer (SOEC) include a battery consisting of an air electrode, a fuel electrode and a solid electrolyte with oxygen ion conductivity. In this case, the battery may be referred to as a solid oxide battery. The solid oxide battery generates electrical energy by electrochemical reaction, or generates hydrogen by electrolyzing water through the reverse reaction of the solid oxide fuel cell. Compared with other types of electrolytic cells or fuel cells (such as phosphoric acid fuel cells (PAFC), alkaline fuel cells (AFC), polymer electrolyte fuel cells (PEMFC) and direct methanol fuel cells (DMFC)), solid oxide batteries have low overvoltage and low irreversible losses based on low activation polarization, and thus have high efficiency. In addition, since this solid oxide battery can be used with carbon or hydrocarbon-based fuels and hydrogen, there is a wide range of fuel selection, and since the reaction rate at the electrode is high, the solid oxide battery has the advantage of not requiring relatively expensive precious metals as electrode catalysts.

[0003] Solid oxide cells are typically used in a stacked structure disposed between a pair of end plates, and in this case, the end plates may include flow paths through which a fluid may flow. In this technical field, there is an increasing need to improve the efficiency of introducing air into solid oxide cells or the reliability of solid oxide cell stacks. Summary of the invention

[0004] Technical issues

[0005] One aspect of the present disclosure is to achieve a solid oxide cell stack having end plates with improved air inflow efficiency.

[0006] Technical solutions to technical problems

[0007] According to one aspect of the present disclosure, a novel structure of a solid oxide cell stack is provided. The solid oxide cell stack includes: a first end plate having a flow path; a solid oxide cell disposed on the first end plate; and a second end plate including a lower region and an upper region, the lower region being disposed on the solid oxide cell and having a first through hole, the upper region being disposed on the lower region and having a second through hole. In the second end plate, the inner side wall of the upper region forming the second through hole is inclined so that the width of the second through hole increases in an upward direction.

[0008] In an embodiment, a width of the second through hole may be greater than a width of the first through hole.

[0009] In an embodiment, when viewed from above, a plurality of first through holes may be disposed within the second through hole.

[0010] In an embodiment, the upper region may include a plurality of second through holes.

[0011] In an embodiment, when viewed from above, a plurality of the first through holes may be provided in each of the plurality of the second through holes.

[0012] In an embodiment, the first through hole may have a uniform width.

[0013] In an embodiment, an inner sidewall of the lower region forming the first through hole may be disposed perpendicular to an upper surface of the solid oxide cell.

[0014] In an embodiment, the thickness of the upper region may be greater than the thickness of the lower region.

[0015] In an embodiment, the thickness of the lower region may be greater than or equal to the thickness of the upper region.

[0016] In an embodiment, the solid oxide cell stack may further include a fastening portion coupling the first end plate and the second end plate.

[0017] In an embodiment, a thermal expansion coefficient of the fastening portion may be lower than thermal expansion coefficients of the first end plate and the second end plate.

[0018] In an embodiment, a current collecting layer may be formed on a surface of at least one of the first end plate and the second end plate facing the solid oxide cell.

[0019] In an embodiment, the solid oxide cell stack may further include a terminal portion connected to the current collecting layer.

[0020] In an embodiment, the first end plate may include a groove disposed around the flow path, and the first end plate may further include a sealant disposed in the groove to cover a side surface of the solid oxide cell.

[0021] In an embodiment, the solid oxide cell stack may further include a gasket and a stopper disposed outside the flow path between the first end plate and the second end plate.

[0022] In an embodiment, the solid oxide cell may include a fuel electrode, an air electrode, and an electrolyte disposed between the fuel electrode and the air electrode, the fuel electrode may be disposed on the first end plate side, and the air electrode may be disposed on the second end plate side.

[0023] According to another aspect of the present disclosure, a solid oxide cell stack includes: a first end plate having a flow path; a solid oxide cell disposed on the first end plate; and a second end plate including a lower region and an upper region, the lower region being disposed on the solid oxide cell and having a first through hole, the upper region being disposed on the lower region and having a second through hole. When viewed from above, a plurality of the first through holes are disposed in the second through hole.

[0024] In an embodiment, the width of the second through hole increases in an upward direction.

[0025] In an embodiment, the width of the first through hole is constant along the upward direction.

[0026] Technical Effects of the Invention

[0027] In the case of the solid oxide cell stack according to the example, when used as a fuel cell or a water electrolysis cell, the performance can be improved by providing an end plate with improved air inflow efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 is a perspective view schematically showing the appearance of a solid oxide battery stack according to an embodiment;

[0029] Figure 2 Shown along Figure 1 An example of a cross section taken along line II' in a solid oxide battery stack;

[0030] Figures 3 to 11 Shows Figure 1 Components of a solid oxide battery stack; and

[0031] Fig.12 and Fig.13 The connection structure of the solid oxide cell stack is shown. DETAILED DESCRIPTION

[0032] Hereinafter, embodiments will be described with reference to specific embodiments and the accompanying drawings. However, the embodiments of the present disclosure may be modified in many different forms, and the scope of the present disclosure is not limited to the embodiments described below. In addition, the embodiments of the present disclosure are provided in order to more completely describe the present disclosure to those skilled in the art. Therefore, in order to illustrate more clearly, the shapes and sizes of the elements in the drawings may be exaggerated, and the elements indicated by the same reference numerals in the drawings are the same elements.

[0033] In the drawings, in order to clearly describe the present disclosure, parts irrelevant to the description are omitted, and in order to clearly express various layers and regions, the thickness is magnified and shown, and the same reference numerals are used to describe elements having the same functions within the scope of the same concept. In addition, throughout the specification, unless otherwise specified, when a component is mentioned as "including...", it means that it may further include other components without excluding other components.

[0034] Figure 1 is a perspective view schematically showing the appearance of a solid oxide cell stack according to an embodiment. Figure 2 Shows a view taken along line II' Figure 1 Example of a cross-sectional view of a solid oxide battery stack. Figures 3 to 11 Shows Figure 1 Components of a solid oxide battery stack.

[0035] The solid oxide cell stack 100 according to the embodiment includes a first end plate 101, a solid oxide cell 120, and a second end plate 102 as main components. In this case, the second end plate 102 includes a lower region 102a having a first through hole H1 and an upper region 120b including a second through hole H2. In the second end plate 102, the inner side wall of the upper region 102b forming the second through hole H2 is inclined so that the width W2 increases as the second through hole H2 increases upward, and by having such a through hole structure, the efficiency of gas flowing into and out of the solid oxide cell stack 100 can be significantly improved. Hereinafter, the components of the solid oxide cell stack 100 will be described in detail, and the case where the solid oxide cell stack 100 is used as a fuel cell will be mainly described. However, the solid oxide cell stack 100 can also be used as an electrolytic cell, and in this case, the opposite reaction to the case of the fuel cell will occur in the fuel electrode 121 and the air electrode 123 of the solid oxide cell 120.

[0036] The first end plate 101 and the second end plate 102 may include a metal having a high melting point so that it does not melt or soften even when the solid oxide battery 120 is operated at a high temperature, and may have a planar structure of such a metal. For example, the first end plate 101 and the second end plate 102 may use a material such as a nickel-based material, an iron-based material, or a stainless steel material. In addition, when the use temperature of the solid oxide battery stack 100 is relatively low (for example, if it is as low as 800° C. or less), copper or a copper alloy having good electrical conductivity may be used.

[0037] Reference Figure 3, the first end plate 101 includes a flow path 106 through which the fluid flows, and in this case, the flow path 106 may be implemented in a tortuous shape, for example, a serpentine slit structure. The serpentine flow path 106 may allow the fuel injected through the fluid inlet 104 to be uniformly supplied to the solid oxide cell 120. Figure 3 , the current collecting layer 103 may be formed on the surface of the first end plate 101 facing the solid oxide battery 120. The current collecting layer 103 may preferably have excellent oxidation resistance to maintain excellent conductivity. In view of these characteristics, the current collecting layer 103 may be formed by coating a material such as gold or silver. In this case, the coating process may use electroplating or electroless plating, deposition, etc. to prevent delamination at high temperatures. In addition, as will be described later, an additional current collecting layer 108 may also be formed on the surface of the second end plate 102 facing the solid oxide battery 120. However, it is not necessary to form the current collecting layers 103 and 108 on both the first end plate 101 and the second end plate 102. The ceramic coating 101I may be formed on at least a portion of the remaining area of ​​the first end plate 101 except for the area where the current collecting layer 103 is formed. The ceramic coating 101I provides excellent oxidation resistance at high temperatures, and thus the durability of the first end plate 101 can be improved. In addition, the ceramic coating 102I may be formed on at least a portion of the remaining area of ​​the second end plate 102 except for the area where the current collecting layer 108 is formed. However, it will not necessarily be necessary to form the ceramic coating on both the first end plate 101 and the second end plate 102.

[0038] like Figure 3 As shown, the first end plate 101 may include a fluid inlet 104 and a fluid outlet 105. In this case, the fluid inlet 104 and the fluid outlet 105 may be respectively arranged on opposite sides of the first end plate 101, and may also be arranged in positions facing each other. As will be described later, in a plurality of solid oxide cell stacks 100, the fluid inlet 104 and the fluid outlet 105 may be connected in series with each other or in parallel with each other, and for this purpose, may be designed to have different sizes to be combined in pairs. In addition, a marking portion M may be formed on the first end plate 101 so that the fuel electrode 121 and the air electrode 123 of the solid oxide cell 120 are positioned in a set direction to prevent assembly errors from occurring.

[0039] The first end plate 101 may have a through hole 107a in the outer portion to be coupled to the second end plate 102. Similarly, the second end plate 102 may also have a through hole in the outer portion (see Fig. 9 The fastening portion 130 may be disposed in the through hole 107a of the first end plate 101 and the through hole 107b of the second end plate 102 to combine the first end plate 101 with the second end plate 102. In addition, the first end plate 101 may include a groove G formed around the flow path 106, and as shown in FIG. Figure 4As shown, the inner gasket 110 may be disposed in the groove G. The inner gasket 110 may perform a main sealing function with respect to gas or liquid, but the inner gasket 110 may not be included according to an embodiment.

[0040] Reference Figure 5 , the solid oxide cell 120 is disposed on the first end plate 101, and corresponds to a functional layer of a fuel cell or a water electrolysis cell. In detail, the solid oxide cell 120 may include a fuel electrode 121, an electrolyte 122, and an air electrode 123, and in this case, the fuel electrode 121 may be disposed on the first end plate 101 side, and the air electrode 123 may be disposed on the second end plate 102 side. In the case of a fuel cell, for example, in the fuel electrode 121, water may be generated due to a hydrogen oxidation reaction or a carbon compound oxidation reaction, and an oxygen ion generation reaction due to oxygen decomposition may occur in the air electrode 123. In the case of a water electrolysis cell, the opposite reaction may occur, for example, hydrogen may be generated by the fuel electrode 121 according to a reduction reaction of water, and oxygen may be generated by the air electrode 123. As another example, in the case of a fuel cell, a hydrogen decomposition (hydrogen ion generation) reaction may occur in the fuel electrode 121, and oxygen ions and hydrogen ions are combined in the air electrode 123 to generate water. In the case of a water electrolysis cell, a decomposition reaction of water (generating hydrogen and oxygen ions) occurs from the fuel electrode 121, and oxygen gas can be generated through the air electrode 123. In the electrolyte 122, ions can move to the fuel electrode 121 or the air electrode 123.

[0041] The fuel electrode 121, the electrolyte 122 and the air electrode 123 may include a solid oxide. In detail, the fuel electrode 121 may include a metal ceramic layer, and the metal ceramic layer includes a metal-containing phase and a ceramic phase. In this case, 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 may be in an oxide state. In the case of the ceramic phase of the fuel electrode 121, gadolinium oxide-doped ceria (GDC), samarium oxide-doped ceria (SDC), ytterbium oxide-doped ceria (YDC), scandium oxide-stabilized zirconia (SSZ), ytterbium oxide ceria scandium oxide-stabilized zirconia (YbCSSZ), etc. may be included.

[0042] The electrolyte 122 may include stabilized zirconia. Specifically, the electrolyte 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.

[0043] The air electrode 123 may include a conductive material, for example, a conductive perovskite material such as lanthanum strontium manganese (LSM). Other conductive perovskites may also be used, for example, 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 0.1 O3 (LSCN) or Pt metal. In some embodiments, the air electrode 123 may include a mixture of a conductive material and an ion conductive ceramic material. For example, the air electrode 123 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. In this case, the ion conductive material may include a zirconia-based material and / or a ceria-based material.

[0044] Reference Figures 6 to 8 , a gasket 111 and a stopper 112 may be provided on the outside of the flow path 106 between the first end plate 101 and the second end plate 102, and a sealant 113 covering the side surface of the solid oxide cell 120 may be provided in a groove of the first end plate 101. In this case, as will be described later, when a compressive force acts on the fastening part 130, the stopper 112 may maintain a distance between the first end plate 101 and the second end plate 102 to prevent the solid oxide cell 120 from being damaged. However, according to an embodiment, at least one of the gasket 111, the stopper 112, and the sealant 113 may be excluded. The sealant 113 may perform a secondary sealing function and may be provided inside the gasket 111 and the stopper 112 and outside the solid oxide cell 120 and the inner gasket 110. The sealant 113 may be formed using a glass-based material, and in this case, the structure is densified at a high temperature, and thus, leakage of liquid or gas may be prevented.

[0045] Will refer to Figures 9 to 11Describe the second end plate. The second end plate 102 may include a current collecting layer 108, which is disposed on the solid oxide cell 120 and formed on the surface facing the solid oxide cell 120 as described above. The second end plate 102 includes a lower region 102a having a first through hole H1 and an upper region 102b disposed on the lower region 102a and including a second through hole H2. In the second end plate 102, the inner side wall of the upper region 102b forming the second through hole H2 is inclined so that the width W2 increases as the second through hole H2 increases upward. In this case, the first through hole H1 and the second through hole H2 may be connected to each other in the vertical direction. As in the present embodiment, the second end plate 102 has a second through hole H2, through which a gas such as air can be introduced and discharged. In the present embodiment, the shape of the second through hole H2 is implemented as a tapered structure so that the gas can be smoothly introduced and discharged by natural convection.

[0046] When describing the multi-level structure of the second end plate 102 in more detail, first, it is preferred that the second end plate 102 maintains rigidity to the extent that there is no deformation when the solid oxide cell 120 is compressed. To this end, the first through hole H1 may be vertically disposed in the lower region 102a adjacent to the solid oxide cell 120. For example, the inner side wall of the lower region 102a forming the first through hole H1 may be disposed perpendicular to the upper surface of the solid oxide cell 120. In the case of the upper region 102b where a gas such as air is introduced, the second through hole H2 is implemented in an inclined shape so that the width increases toward the top, thereby improving the inflow and outflow efficiency of the gas. In this case, the first through hole H1 may be implemented to have a uniform width W1.

[0047] As shown, the width of the second through hole H2 may be greater than the width of the first through hole H1 (W2>W1), and in this case, the width may be a length measured in a horizontal direction perpendicular to the vertical direction based on the drawing. Fig. 9 As shown, when viewed from the top of the solid oxide cell stack 100, the plurality of first through holes H1 may be disposed in the second through hole H2. In addition, the upper region 102b may include a plurality of second through holes H2, and in this case, when viewed from the top of the solid oxide cell stack 100, the plurality of first through holes H1 may be disposed in each of the plurality of second through holes H2. In this way, when the plurality of first through holes H1 are disposed in the second through hole H2 in a tapered shape, since the area of ​​the through hole (i.e., the second through hole) opened to the outside can be further increased, the gas inflow and outflow efficiency can be improved.

[0048] In addition, the thickness h1 of the lower region 102a of the second end plate 102 and the thickness h2 of the upper region 102b may vary according to the overall thickness of the second end plate 102. First, in an embodiment, the thickness of the upper region 102b may be greater than the thickness of the lower region 102a (h2>h1). In the case where the second end plate 102 has sufficient rigidity or is designed to be thick enough so that the compression force generated by the fastening portion 130 or the like does not cause deformation, the thickness of the upper region 102b may be formed to be greater than the thickness of the lower region 102a to more smoothly introduce air. Alternatively, in the case where the second end plate 102 does not have sufficient rigidity, the thickness of the lower region 102a may be greater than the thickness of the upper region 102b (h1>h2), or may be the same as the thickness of the upper region 102b (h1=h2).

[0049] Reference Fig.11 , which shows a form in which the first end plate 101 and the second end plate 102 are combined with each other by a fastening portion 130. In order to connect the first end plate 101 and the second end plate 102, the fastening portion 130 may be screwed into the through hole on the outside of the first end plate 101 and the second end plate 102. In this embodiment, the fastening portion 130 may have a thermal expansion coefficient lower than that of the first end plate 101 and the second end plate 102. Even when the fastening portion 130 is not tightly bonded to the first end plate 101 and the second end plate 102 at room temperature, a stable fastening structure can be obtained due to the compression force generated by the fastening portion 130 having a relatively low thermal expansion rate. The thermal expansion coefficients of the fastening portion 130 and the end plates 101 and 102 can be designed to provide the required compression force at the target operating temperature. In detail, the fastening part 130 uses the same material as the base material of the end plates 101 and 102 (e.g., nickel-based material, iron-based material, stainless steel-based material, copper-based material, etc.), but a material of a different composition having a low thermal expansion coefficient may also be used. In the case where the fastening part 130 has conductivity, since an unintended current path may be generated, an insulating coating may be additionally formed on the surface of the fastening part 130. In addition, a separate insulator 130I may be inserted between the fastening part 130 and the inner wall of the through hole of the plates 101 and 102.

[0050] On the other hand, Figure 1 As shown, the solid oxide cell stack 100 may further include terminal portions 141 and 142 respectively connected to the current collecting layers 103 and 108. As will be described later, a plurality of solid oxide cell stacks 100 may be electrically connected to each other through the terminal portions 141 and 142.

[0051] The solid oxide battery stack 100 may be provided as a plurality of solid oxide battery stacks 100 to provide a structure in which they are connected to each other. Fig.12 and Fig.13The forms of the solid oxide battery stack 100 being connected in series and in parallel are shown respectively. By using the solid oxide battery stack 100 in the form of a connection structure, the use for high voltage or high current can be expanded. In this case, the solid oxide battery stack 100 becomes a unit stack, and may be provided with a connection conductor 150 for electrical connection to each other and a connection flow path 160 used as a fluid connection flow path. The connection structure of the solid oxide battery stack 100 may include a fluid inlet 161, a fluid outlet 162, and terminal portions 151 and 152.

[0052] As described above, in the case of the solid oxide cell stack according to the example, the performance when the solid oxide cell stack according to the example is used as a fuel cell or a water electrolysis cell can be improved by providing an end plate having improved air inflow efficiency.

[0053] While example embodiments have been shown and described above, it will be readily apparent to those skilled in the art that modifications and variations may be made without departing from the scope of the present disclosure as defined by the appended claims.

Claims

1. A solid oxide battery stack, comprising: A first end plate having a flow path; A solid oxide cell disposed on the first end plate; as well as a second end plate, comprising a lower region and an upper region, the lower region being disposed on the solid oxide cell and having a first through hole, the upper region being disposed on the lower region and having a second through hole, Wherein, in the second end plate, the inner side wall of the upper region forming the second through hole is inclined so that the width of the second through hole increases in an upward direction.

2. The solid oxide battery stack according to claim 1, wherein: The width of the second through hole is greater than the width of the first through hole.

3. The solid oxide battery stack according to claim 2, wherein: When viewed from above, a plurality of the first through holes are arranged in the second through hole.

4. The solid oxide battery stack according to claim 2, wherein: The upper region includes a plurality of the second through holes.

5. The solid oxide battery stack according to claim 4, wherein: When viewed from above, a plurality of the first through holes are provided in each of the plurality of the second through holes.

6. The solid oxide battery stack according to claim 1, wherein: The first through hole has a uniform width.

7. The solid oxide battery stack according to claim 1, wherein: The inner sidewall of the lower region forming the first through hole is arranged perpendicular to the upper surface of the solid oxide cell.

8. The solid oxide battery stack according to claim 1, wherein: The thickness of the upper region is greater than the thickness of the lower region.

9. The solid oxide battery stack according to claim 1, wherein: The thickness of the lower region is greater than or equal to the thickness of the upper region. 10 . The solid oxide cell stack according to claim 1 , further comprising a fastening portion combining the first end plate and the second end plate.

11. The solid oxide battery stack according to claim 10, wherein: The fastening portion may have a lower thermal expansion coefficient than the first end plate and the second end plate.

12. The solid oxide battery stack according to claim 1, wherein: A current collecting layer is disposed on a surface of at least one of the first end plate and the second end plate that faces the solid oxide cell. 13 . The solid oxide cell stack according to claim 12 , further comprising a terminal portion connected to the current collecting layer.

14. The solid oxide battery stack according to claim 12, wherein: In at least one of the first end plate and the second end plate, a ceramic coating is provided in at least a portion of a region other than a region where the current collecting layer is provided.

15. The solid oxide battery stack according to claim 1, wherein: The first end plate includes a groove disposed around the flow path, and the first end plate further includes a sealant disposed in the groove to cover a side surface of the solid oxide cell. 16 . The solid oxide cell stack of claim 1 , further comprising a gasket and a stopper disposed outside the flow path between the first end plate and the second end plate.

17. The solid oxide battery stack according to claim 1, wherein: The solid oxide cell includes a fuel electrode, an air electrode, and an electrolyte disposed between the fuel electrode and the air electrode. wherein the fuel electrode is disposed on the first end plate side, and the air electrode is disposed on the second end plate side.

18. A solid oxide battery stack comprising: A first end plate having a flow path; A solid oxide cell disposed on the first end plate; as well as a second end plate, comprising a lower region and an upper region, the lower region being disposed on the solid oxide cell and having a first through hole, the upper region being disposed on the lower region and having a second through hole, Wherein, when viewed from above, a plurality of the first through holes are arranged in the second through hole.

19. The solid oxide battery stack according to claim 18, wherein: The width of the second through hole increases in an upward direction.

20. The solid oxide battery stack according to claim 18, wherein: The width of the first through hole is constant in an upward direction.

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