Solid oxide battery and method for operating same

Abstract

Disclosed is a solid oxide battery including: a unit cell including a solid oxide electrolyte including a first solid oxide electrolyte layer and a second solid oxide electrolyte layer, and a fuel electrode and an air electrode; and a frame having a first manifold surrounding a side surface of the unit cell and through which air supplied to the first solid oxide electrolyte layer flows.

Description

Technical Field

[0001] This application claims the benefit of priority from Korean Patent Application No. 10-2022-0169584 filed on December 7, 2023, in the Korean Intellectual Property Office, and Korean Patent Application No. 10-2023-0021184 filed on February 17, 2023, in the Korean Intellectual Property Office, the entire contents of which are incorporated herein by reference.

[0002] The present disclosure relates to a solid oxide cell and an operating method thereof, wherein the gas separation function of the solid oxide electrolyte can be maintained while ensuring the ductility of the material to improve mechanical properties and long-term reliability, and the cell performance and efficiency of the solid oxide cell can be improved by improving oxygen ion conductivity. Background Art

[0003] A solid oxide cell (SOC) is, for example, a solid oxide fuel cell (SOFC) or a solid oxide electrolysis cell (SOEC), and generates electrical energy through an electrochemical reaction of a cell (composed of an air electrode, a fuel electrode, and a solid oxide electrolyte having oxygen ion conductivity), or electrolyzes water and generates hydrogen through the reverse reaction of a solid oxide fuel cell.

[0004] The solid oxide cell has a structure in which an air electrode and a fuel electrode are arranged on both sides of a solid oxide electrolyte having oxygen ion conductivity to supply air and fuel to the air electrode and the fuel electrode respectively through flow paths formed in a separator, thereby generating electricity or causing electrolysis through an electrochemical reaction.

[0005] The air electrode and the fuel electrode are where the reaction actually takes place, and in order for the reaction to be effective, they generally must have a porous structure so that the gas can easily pass through the air electrode and the fuel electrode. In contrast, a solid oxide electrolyte generally has a dense structure that separates the various spaces so that the air and fuel do not pass through the solid oxide electrolyte.

[0006] However, solid oxide electrolytes are generally very brittle materials and may therefore be easily damaged by residual stress generated during the process, chemical stress caused by oxygen partial pressure differences, stress caused by external loads, etc. In addition, even when the stress level does not exceed the yield strength, there is a risk of fatigue failure or creep failure under high temperature operating conditions, so it is necessary to minimize the residual stress.

[0007] The thickness of the solid oxide electrolyte may be increased to a predetermined level or more to maintain structural rigidity, but since the thickness is inversely proportional to the ionic conductivity of the solid oxide electrolyte, this method is accompanied by degradation of characteristics of the device. Summary of the invention

[0008] Technical issues

[0009] One aspect of the present disclosure provides a solid oxide cell that exhibits improved mechanical properties and long-term reliability by maintaining the gas separation function of a solid oxide electrolyte while ensuring the ductility of the material, and also exhibits improved cell performance and efficiency by improving oxygen ion conductivity.

[0010] Solutions to the problem

[0011] According to some embodiments of the present disclosure, a solid oxide cell includes: a unit cell, the unit cell including a solid oxide electrolyte and a fuel electrode and an air electrode, the solid oxide electrolyte including a first solid oxide electrolyte layer and a second solid oxide electrolyte layer, the second solid oxide electrolyte layer is disclosed on one surface or both surfaces of the first solid oxide electrolyte layer and has a density higher than that of the first solid oxide electrolyte layer, the fuel electrode is arranged on one surface of the solid oxide electrolyte, and the air electrode is arranged on the opposite surface of the solid oxide electrolyte; and a frame having a first manifold surrounding the side of the unit cell, and air supplied to the first solid oxide electrolyte layer flows through the first manifold.

[0012] The air may be dry air having a relative humidity of 0% to 5%.

[0013] The first manifold may penetrate the frame in a direction perpendicular to the sides of the unit cells.

[0014] The frame may have a window to accommodate the unit cells.

[0015] The frame may have a plurality of through holes connecting the window and the first manifold.

[0016] The frame may further have a second manifold through which the fuel supplied to the fuel electrode flows.

[0017] The frame may further include a third manifold through which air supplied to the air electrode flows.

[0018] The frame may have a through hole connecting the window and the third manifold.

[0019] The solid oxide cell may supply air to the air electrode through the first manifold.

[0020] The solid oxide cell may further include a first separator disposed on one surface of the unit cell and having a flow path configured to supply the fuel to a surface facing the fuel electrode.

[0021] The solid oxide cell may further include a second separator disposed on the other surface of the unit cell and having a flow path configured to supply air to a surface facing the air electrode.

[0022] The frame, the first partition, the second partition, or a combination thereof may be integrated with each other.

[0023] The second solid oxide electrolyte layer may have a density level greater than or equal to about 90%.

[0024] The first solid oxide electrolyte layer may have a density level of less than or equal to about 75%.

[0025] The second solid oxide electrolyte layer may have an average thickness of less than or equal to about 10 μm.

[0026] The first solid oxide electrolyte layer may have an average thickness greater than or equal to about 1 μm.

[0027] The first solid oxide electrolyte layer or the second solid oxide electrolyte layer may include yttria-stabilized zirconia (YSZ), scandia-stabilized zirconia (ScSZ), gadolinium oxide-doped ceria (GDC), samarium oxide-doped ceria (SDC), strontium and magnesium-doped lanthanum gallate (LSGM), barium zirconate doped with samarium oxide and ceria (BaZrO3), barium ceria doped with samarium oxide and ceria (BaCeO3), bismuth oxide (Bi2O3), or a combination thereof.

[0028] The first solid oxide electrolyte layer may include yttria-stabilized zirconia (YSZ), scandia-stabilized zirconia (ScSZ), or a combination thereof.

[0029] The second solid oxide electrolyte layer may include gadolinium oxide-doped ceria (GDC), samarium oxide-doped ceria (SDC), or a combination thereof.

[0030] The solid oxide cell may be a solid oxide fuel cell (SOFC), a solid oxide electrolyzer (SOEC), or both.

[0031] According to another aspect, a method for operating a solid oxide cell includes: in a solid oxide cell including a unit cell, the unit cell includes a solid oxide electrolyte, the solid oxide electrolyte includes a first solid oxide electrolyte layer and a second solid oxide electrolyte layer, the second solid oxide electrolyte layer is disclosed on one surface or both surfaces of the first solid oxide electrolyte layer and has a density higher than that of the first solid oxide electrolyte layer; supplying fuel to the fuel electrode; and supplying dry air to the first solid oxide electrolyte layer.

[0032] The dry air may have a relative humidity of about 0% to about 5%.

[0033] Air may be supplied to the air electrode.

[0034] Advantageous Effects of the Invention

[0035] Based on the solid oxide battery according to one aspect, battery performance and efficiency can be improved by maintaining the gas separation function of the solid oxide electrolyte while ensuring the ductility of the material, and mechanical properties and long-term reliability can also be improved by improving oxygen ion conductivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 is an exploded perspective view of a solid oxide cell according to one aspect.

[0037] Figure 2 is a perspective view showing a modified embodiment of the frame.

[0038] Figure 3 is a perspective view showing another modified embodiment of the frame.

[0039] Figure 4 is a schematic diagram showing a solid oxide fuel cell according to a modified embodiment of an aspect.

[0040] Figure 5 is a schematic diagram showing a solid oxide water electrolysis cell according to another variant embodiment of the one aspect.

[0041] Figure 6 is a schematic diagram for explaining a method of operating a solid oxide cell according to another aspect. DETAILED DESCRIPTION

[0042] Hereinafter, the present embodiment will be described in detail with reference to the accompanying drawings so that ordinary technicians in the field can practice. The drawings and descriptions are essentially considered to be illustrative and not restrictive. Throughout the specification, the same reference numerals represent the same elements. In addition, the drawings are provided only to make the embodiments disclosed in this specification easy to understand, and should not be interpreted as limiting the spirit disclosed in this specification, and it should be understood that the present embodiment includes all variants, equivalents and alternatives without departing from the scope and spirit of the present embodiment. In addition, some components are exaggerated, omitted or schematically depicted in the drawings, and the size of each component does not necessarily indicate the actual size.

[0043] In addition, unless explicitly described to the contrary, the word “comprise” and variations such as “including” or “having”, will be understood to imply the inclusion of stated elements but not the exclusion of any other elements.

[0044] As used herein, the term "about" means approximately. Generally, the term "about" is used herein to modify numerical values ​​that are above and below the stated value with a variance of 10%. On the one hand, the term "about" means the numerical value of the number with which it is used plus or minus 20%.

[0045] Figure 1 is an exploded perspective view of a solid oxide cell 100 according to one aspect.

[0046] Reference Figure 1 The solid oxide battery 100 includes a unit cell 105 and a frame 140 surrounding the unit cell 105 .

[0047] The unit cell 105 includes: a solid oxide electrolyte 130 ; and a fuel electrode (not shown) disposed on one side of the solid oxide electrolyte 130 ; and an air electrode 120 disposed on the other side of the solid oxide electrolyte 130 .

[0048] The air electrode 120 includes an air electrode material. The air electrode material may be a material that reduces oxygen to oxygen ions.

[0049] For example, the air electrode material may include metal oxide particles having a perovskite crystal structure. Perovskite metal oxides are mixed ion electron conductor (MIEC) materials having both ion conductivity and electronic conductivity, and have high oxygen diffusion coefficients and charge exchange reaction rate coefficients, so that redox reactions occur over the entire surface of the electrode, rather than just at the three-phase interface.

[0050] The perovskite type metal oxide may be represented by Chemical Formula 1.

[0051] [Chemical formula 1]

[0052] ABO3±γ

[0053] In Chemical Formula 1, A is an element including La, Ba, Sr, Sm, Gd, Ca or a combination thereof, B is an element including Mn, Fe, Co, Ni, Cu, Ti, Nb, Cr, Sc or a combination thereof, and γ is a number and indicates oxygen excess or oxygen deficiency. γ may be, for example, in the range of 0≤γ≤0.3.

[0054] For example, the perovskite type metal oxide may be represented by Chemical Formula 2.

[0055] [Chemical formula 2]

[0056] A' 1-x A” x B'O 3±γ

[0057] In Chemical Formula 2, A' is an element including Ba, La, Sm or a combination thereof, A" is an element including Sr, Ca, Ba or a combination thereof and is different from A', B' is an element including Mn, Fe, Co, Ni, Cu, Ti, Nb, Cr, Sc or a combination thereof, x is a number in the range of 0≤x<1, and γ is a number and represents oxygen excess or oxygen deficiency. γ may be in the range of, for example, 0≤γ≤0.3.

[0058] For example, the air electrode material may include lanthanum strontium manganese oxide (LSM), lanthanum strontium iron oxide (LSF), lanthanum strontium cobalt oxide (LSC), lanthanum strontium cobalt iron oxide (LSCF), samarium strontium cobalt oxide (SSC), barium strontium cobalt iron oxide (BSCF), bismuth ruthenium oxide, or combinations thereof.

[0059] The air electrode 120 may also include a solid oxide electrolyte material.

[0060] For example, the solid oxide electrolyte material may include yttria-stabilized zirconia (YSZ), scandia-stabilized zirconia (ScSZ), gadolinia-doped ceria (GDC), samarium oxide-doped ceria (SDC), strontium and magnesium-doped lanthanum gallate (LSGM), barium zirconate doped with samarium oxide and ceria (BaZrO3), barium ceria doped with samarium oxide and ceria (BaCeO3), bismuth oxide (Bi2O3), or a combination thereof.

[0061] In this case, when the solid oxide electrolyte material is yttria-stabilized zirconia (YSZ) and the air electrode material is lanthanum strontium manganese oxide (LSM), the air electrode may include a LSM-YSZ composite.

[0062] The air electrode 120 may have a thickness of, for example, about 1 μm to about 100 μm or about 5 μm to about 50 μm.

[0063] The fuel electrode plays a role in the electrochemical oxidation of the fuel and charge transfer.

[0064] For example, the fuel electrode material may include pure metals such as nickel (Ni), cobalt (Co), ruthenium (Ru), palladium (Pd), or platinum (Pt), or oxides thereof.

[0065] The fuel electrode may also include a solid oxide electrolyte material.

[0066] For example, the solid oxide electrolyte material may include yttria-stabilized zirconia (YSZ), scandia-stabilized zirconia (ScSZ), gadolinia-doped ceria (GDC), samarium oxide-doped ceria (SDC), strontium and magnesium-doped lanthanum gallate (LSGM), barium zirconate doped with samarium oxide and ceria (BaZrO3), barium ceria doped with samarium oxide and ceria (BaCeO3), bismuth oxide (Bi2O3), or a combination thereof.

[0067] In this case, the fuel electrode may include a cermet in which the fuel electrode material and the solid oxide electrolyte material are combined. For example, when the solid oxide electrolyte material is yttria-stabilized zirconia (YSZ) and the fuel electrode material is nickel (Ni), the porous solid oxide composite may be a Ni / YSZ cermet, and when the fuel electrode material is ruthenium (Ru), the porous solid oxide composite may be a Ru / YSZ cermet.

[0068] For example, the fuel electrode may have a thickness of, for example, about 1 μm to about 1000 μm or about 5 μm to about 100 μm.

[0069] The solid oxide electrolyte 130 plays a role in transporting oxygen ions generated from the air electrode 120 to the fuel electrode through ion conduction.

[0070] The solid oxide electrolyte 130 has airtightness to prevent contact between the air electrode and the fuel electrode, and also prevents electrons generated at the fuel electrode from moving directly toward the air electrode 120 due to high oxygen ion conductivity and low electron conductivity (high resistance, high insulation).

[0071] In addition, since the solid oxide electrolyte 130 has the air electrode 120 and the fuel electrode on both sides thereof where the oxygen partial pressure is very large, the aforementioned properties may be required to maintain a wide oxygen partial pressure region.

[0072] Therefore, solid oxide electrolyte 130 includes a first solid oxide electrolyte layer 131 and a second solid oxide electrolyte layer 132 provided on one surface or both surfaces of first solid oxide electrolyte layer 131. Here, first solid oxide electrolyte layer 131 has a density lower than that of second solid oxide electrolyte layer 132. In other words, first solid oxide electrolyte layer 131 is more porous than second solid oxide electrolyte layer 132, and, for example, has a higher porosity.

[0073] Therefore, the solid oxide electrolyte 130 has the dense second solid oxide electrolyte layer 132 disposed on one surface or both surfaces of the porous first solid oxide electrolyte layer 131, and thus may have mechanical ductility.

[0074] In addition, since the porous structure of the first solid oxide electrolyte layer 131 naturally leads to an increase in specific surface area (surface area to volume ratio), and the solid oxide electrolyte 130 has more oxygen vacancies on the surface than inside, an effect of improving ion conductivity can be expected. Since oxygen ions of the solid oxide are conducted by a hopping mode in which oxygen ions move while exchanging vacancies, ion conductivity is proportional to the concentration of oxygen vacancies.

[0075] For example, second solid oxide electrolyte layer 132 may have a density degree higher than or equal to 90%, and first solid oxide electrolyte layer 131 may have a density degree less than or equal to 75%.

[0076] Here, the density degree refers to the percentage (%) of the area excluding pores in a cross section of the first solid oxide electrolyte layer 131 or the second solid oxide electrolyte layer 132 to the total area, and can be measured by obtaining a cross section of a sample of the first solid oxide electrolyte layer 131 or the second solid oxide electrolyte layer 132 in the solid oxide battery 100 by CP (cross-section polisher), FIB (focused ion beam), etc., and measuring the area with a scanning electron microscope (SEM) device.

[0077] In addition, in the first solid oxide electrolyte layer 131 or the second solid oxide electrolyte layer 132, the area other than the hole can be measured by analyzing the cross-sectional image taken by SEM with an electron beam microanalyzer (EPMA). When the composition analysis is performed using an electron beam microanalyzer (EPMA), an energy dispersive spectrometer (EDS) or a wavelength dispersive spectrometer (WDS) can be used as an X-ray spectrometer. Alternatively, when the cross section is examined with an SEM, the solid oxide electrolyte material can be identified as a bright portion of the contrast, and the hole can be identified as a dark portion of the contrast. Therefore, the area other than the hole can be calculated by binarizing the SEM image, etc. to obtain the area ratio of the portion with different contrast to the area of ​​the entire measurement area.

[0078] When the second solid oxide electrolyte layer 132 has a density less than 90%, the gas flow may not be completely blocked. When the first solid oxide electrolyte layer 131 has a density greater than 75%, sufficient ductility may not be ensured, causing problems with internal gas flow.

[0079] For example, second solid oxide electrolyte layer 132 may have an average thickness of less than or equal to about 10 μm or less than or equal to about 2 μm. In addition, first solid oxide electrolyte layer 131 may have an average thickness of greater than or equal to about 2 μm. In the case where the average thickness of first solid oxide electrolyte layer 131 is less than about 2 μm, gas supply may not be smooth.

[0080] The materials of these solid oxide electrolytes 130 are not particularly limited as long as they are generally available in the art, and may include, for example, yttria-stabilized zirconia (YSZ), scandia-stabilized zirconia (ScSZ), gadolinia-doped ceria (GDC), samarium oxide-doped ceria (SDC), strontium and magnesium-doped lanthanum gallate (LSGM), barium zirconate doped with samarium oxide and ceria (BaZrO3), barium ceria doped with samarium oxide and ceria (BaCeO3), bismuth oxide (Bi2O3), or combinations thereof.

[0081] In this case, the first solid oxide electrolyte layer 131 and the second solid oxide electrolyte layer 132 may have the same composition, or may have different compositions. For example, the first solid oxide electrolyte layer 131 may include a zirconia-based material such as yttria-stabilized zirconia (YSZ), scandia-stabilized zirconia (ScSZ), or a combination thereof, and the second solid oxide electrolyte layer 132 may include a ceria-based material such as gadolinium oxide-doped ceria (GDC), samarium oxide-doped ceria (SDC), or a combination thereof. However, the solid oxide cell 100 is not limited thereto, but the composition of the first solid oxide electrolyte layer 131 and the second solid oxide electrolyte layer 132 may be determined by considering the characteristics of the fuel electrode and the air electrode 120 and the characteristics of the solid oxide cell 100.

[0082] The method of manufacturing a solid oxide electrolyte 130 in which a second solid oxide electrolyte layer 132 is disposed on one surface or both surfaces of a first solid oxide electrolyte layer 131 is not particularly limited, but may include, for example, adding a pore former to a raw sheet for forming the first solid oxide electrolyte layer 131, and not adding a pore former to a raw sheet for forming the second solid oxide electrolyte layer 132; stacking the first solid oxide electrolyte layer 131 and the second solid oxide electrolyte layer 132; and firing them simultaneously; or first forming a first solid oxide electrolyte layer 131 having a porous structure, and then coating the second solid oxide electrolyte layer 132 on the surface of the first solid oxide electrolyte layer 131, or separately manufacturing the first solid oxide electrolyte layer 131 and the second solid oxide electrolyte layer 132 and then combining them, and the like.

[0083] Optionally, the solid oxide cell 100 may further include a current collecting layer (not shown) including an electrical conductor on at least one side of the air electrode 120 (eg, the outside of the air electrode 120). The current collecting layer may act as a current collector to collect electricity in the configuration of the air electrode 120.

[0084] The collector layer may include, for example, lanthanum cobalt oxide (LaCoO3), lanthanum strontium cobalt oxide (LSC), lanthanum strontium cobalt iron oxide (LSCF), lanthanum strontium cobalt manganese oxide (LSCM), lanthanum strontium manganese oxide (LSM), lanthanum strontium iron oxide (LSF), or a combination thereof. The collector layer may use the materials listed above alone or in a combination of two or more, wherein these materials may be formed into a single layer or two or more layers having a stacked structure.

[0085] The frame 140 is disposed on the side of the unit cell 105, and, for example, may surround four sides of the unit cell 105. Here, the side of the unit cell 105 may be one of the directions perpendicular to the direction in which the fuel electrode, the solid oxide electrolyte 130, and the air electrode 120 are stacked (hereinafter, referred to as "stacking direction").

[0086] The frame 140 has a window 141 for accommodating the unit battery 105. The window 141 passes through the central portion of the frame 140 in the stacking direction and may have, for example, a rectangular column shape having a width greater than a height. The width of the window 141 may be substantially the same as the width of the unit battery 105. Therefore, the frame 140 may include first to fourth edge portions surrounding the window 141 (the window 141 is located in the center), wherein the first edge portion and the third edge portion face each other, and the second edge portion and the fourth edge portion face each other.

[0087] The frame 140 may have a first manifold 143 through which air supplied to the first solid oxide electrolyte layer 131 flows. Alternatively, the frame 140 may further include a second manifold 144 through which fuel supplied to the fuel electrode flows and a third manifold 145 through which air supplied to the air electrode 120 flows.

[0088] The first manifold 143 , the second manifold 144 , and the third manifold 145 may penetrate the frame 140 in the stacking direction.

[0089] The frame 140 may have each of a plurality of first manifolds 143 , a plurality of second manifolds 144 , and a plurality of third manifolds 145 , for example, four first manifolds 143 , two second manifolds 144 , and two third manifolds 145 .

[0090] Two second manifolds 144 may be respectively disposed on the first edge portion and the third edge portion facing the first edge portion of the frame 140 , and two third manifolds 145 may be respectively disposed on the second edge portion and the fourth edge portion facing the second edge portion of the frame 140 .

[0091] Two first manifolds 143 are respectively disposed at one end and the opposite end of the third manifold 145 at the second edge portion, and another two first manifolds 143 may be respectively disposed at one end and the opposite end of the third manifold 145 at the fourth edge portion. Alternatively, two first manifolds 143 are respectively disposed at one end and the opposite end of the second manifold 144 at the first edge portion, and another two first manifolds 143 may be respectively disposed at one end and the opposite end of the second manifold 144 at the third edge portion. Alternatively, four first manifolds 143 may be respectively disposed at each of the first to fourth edge portions.

[0092] The frame 140 has a plurality of through holes 142 connecting the window 141 with the first manifold 143. The through holes 142 are located between the window 141 and the first manifold 143 and transversely penetrate the frame 140. For example, the through holes 142 may have a tube shape or a window shape.

[0093] Therefore, the air supplied through the first manifold 143 may be directly supplied to the first solid oxide electrolyte layer 131 .

[0094] The first solid oxide electrolyte layer 131 has a porous structure and therefore includes a large number of oxygen vacancies and has high ion conductivity, but when water vapor is present in the surrounding environment (even including general air), the water vapor reacts in the oxygen vacancies on the surface of the first solid oxide electrolyte layer 131, thereby reducing the amount of oxygen vacancies.

[0095] Therefore, dry air may be directly supplied to the first solid oxide electrolyte layer 131 through the first manifold 143 of the frame 140 to prevent the ion conductivity of the first solid oxide electrolyte layer 131 having a porous structure from being deteriorated.

[0096] Dry air directly supplied to first solid oxide electrolyte layer 131 may have a relative humidity of 0% to 5% at room temperature (25° C.) When the dry air has a relative humidity greater than 5%, oxygen ion conductivity of the electrolyte may decrease due to surface adsorption.

[0097] Since the dry air supplied to the first solid oxide electrolyte layer 131 is not consumed but is only used to change the atmosphere of the first solid oxide electrolyte layer 131, it is relatively less important to arrange a flow path for the dry air, unlike other gases (fuel or air) supplied to the fuel electrode or air electrode 120. Therefore, the dry air does not need a specific flow path to be supplied to the first solid oxide electrolyte layer 131, but can be sufficiently supplied from the side of the first solid oxide electrolyte layer 131 through the plurality of through holes 142 connecting the window 141 with the first manifold 143, which also does not limit the arrangement of the plurality of through holes 142.

[0098] Two first manifolds 143 provided at the second edge portion of frame 140 are used to supply dry air to first solid oxide electrolyte layer 131 , and two first manifolds 143 at the fourth edge portion of frame 140 are used to exhaust dry air from first solid oxide electrolyte layer 131 .

[0099] Two first manifolds 143 may be provided at one end and the other end of the third manifold 145 at the second edge portion, and another two first manifolds 143 may be provided at one end and the other end of the third manifold 145 at the fourth edge portion. Alternatively, two first manifolds 143 may be provided at one end and the other end of the second manifold 144 at the first edge portion, and the remaining two first manifolds 143 may be provided at one end and the other end of the second manifold 144 at the third edge portion. Alternatively, four first manifolds 143 may be provided at each edge of the first edge portion to the fourth edge portion.

[0100] Figure 2 is a perspective view showing a modified embodiment of the frame 140 .

[0101] When dry air is supplied to first solid oxide electrolyte layer 131 , first manifold 143 is separated from third manifold 145 , but when dry air is discharged from first solid oxide electrolyte layer 131 , the dry air may be discharged through third manifold 145 without separating third manifold 145 from first manifold 143 .

[0102] Therefore, the frame 140 may have a through hole 142 connecting the window 141 with the third manifold 145. Dry air may be exhausted from the first solid oxide electrolyte layer 131 through the through hole 142 connecting the window 141 with the third manifold 145.

[0103] Reference Figure 2 , the frame 140 may have a plurality of first manifolds 143 , a plurality of second manifolds 144 , and a plurality of third manifolds 145 , for example, two first manifolds 143 , two second manifolds 144 , and two third manifolds 145 .

[0104] The two second manifolds 144 may be respectively disposed at the first edge portion and the third edge portion, the first edge portion and the third edge portion face each other and the window 141 is located in the middle, and the two third manifolds 145 may be respectively disposed at the second edge portion and the fourth edge portion, the second edge portion and the fourth edge portion face each other and the window 141 is located in the middle.

[0105] The two first manifolds 143 may be provided only at one end and the opposite end of the third manifold 145 at the second edge portion.

[0106] The frame 140 may have a plurality of through holes 142 connecting the window 141 with the first manifold 143. In addition, the frame 140 has through holes 142 connecting the window 141 with the third manifold 145 at the fourth edge portion. The frame 140 may not have through holes 142 connecting the window 141 with the third manifold 145 at the second edge portion.

[0107] Figure 3 is a perspective view showing another modified embodiment of the frame 140 .

[0108] Dry air may also be supplied to the air electrode 120 of the solid oxide cell 100 instead of normal air.

[0109] Here, the frame 140 may supply air to the air electrode 120 through the first manifold 143 without additionally including the third manifold 145 .

[0110] Reference Figure 3 , the frame 140 may have a plurality of first manifolds 143 and a plurality of second manifolds 144 , for example, two first manifolds 143 and two second manifolds 144 .

[0111] Two second manifolds 144 may be disposed at the first edge portion and the third edge portion of the frame 140 , the third edge portion facing the first edge portion with the window 141 located in the middle, and two first manifolds 143 may be disposed at the second edge portion and the fourth edge portion of the frame 140 , the fourth edge portion facing the second edge portion.

[0112] Here, the frame 140 has a plurality of through holes 142 connecting the window 141 with the first manifold 143. The through holes 142 are located between the window 141 and the first manifold 143 and pass through the frame 140 in a transverse direction.

[0113] In addition, the solid oxide cell 100 may further include a first separator (not shown) on one surface of the unit cell 105 and a second separator (not shown) on the other surface of the unit cell 105 .

[0114] The first separator and the second separator are respectively disposed between two unit cells 105 to separate fuel and air (oxygen) and also electrically connect the unit cells 105 in series. Therefore, the first separator and the second separator may be formed using a material having high electron conductivity and low ion conductivity.

[0115] The first separator has a central portion and an edge portion surrounding the central portion, wherein the central portion has a flow path for supplying fuel to a surface facing the fuel electrode, and the edge portion may have a first manifold 143, a second manifold 144 and a third manifold 145, air supplied to the first solid oxide electrolyte layer 131 flows through the first manifold 143, fuel supplied to the fuel electrode flows through the second manifold 144, and air supplied to the air electrode 120 flows through the third manifold 145.

[0116] In addition, the second separator has a central portion and an edge portion surrounding the central portion, wherein the central portion has a flow path for supplying air to the surface facing the air electrode 120, and the edge portion may have a first manifold 143, a second manifold 144 and a third manifold 145, the air supplied to the first solid oxide electrolyte layer 131 flows through the first manifold 143, the fuel supplied to the fuel electrode flows through the second manifold 144, and the air supplied to the air electrode 120 flows through the third manifold 145.

[0117] Here, for ease of explanation, the frame 140, the first separator, and the second separator are described as components separated from each other, but the solid oxide cell 100 according to the present aspect is not limited to this, and the frame 140, the first separator, the second separator, or a combination thereof may be a single component that is integrated with or bonded to each other.

[0118] For example, the solid oxide cell may be a solid oxide fuel cell (SOFC), a solid oxide electrolyzer (SOEC), or both.

[0119] Figure 4 is a schematic diagram showing a case in which the solid oxide cell 100 is a solid oxide fuel cell 200 .

[0120] Reference Figure 4 The solid oxide fuel cell 200 includes: a fuel electrode 210; an air electrode 220 facing the fuel electrode 210; and an oxygen ion conductive solid oxide electrolyte 230 disposed between the fuel electrode 210 and the air electrode 220.

[0121] As shown in reaction formula 1, the electrochemical reaction of the solid oxide fuel cell 200 includes an air electrode reaction and a fuel electrode reaction. In the air electrode reaction, the oxygen O2 at the air electrode 220 is converted into oxygen ions O2 - In the fuel electrode reaction, the fuel (H2 or hydrocarbon) of the fuel electrode 210 reacts with the oxygen ions that have moved through the electrolyte.

[0122] [Reaction 1]

[0123] Air electrode reaction: 1 / 2O2+2e - →O2 -

[0124] Fuel electrode reaction: H2+O2 - →H2O+2e -

[0125] In the air electrode 220 of the solid oxide fuel cell 200, oxygen adsorbed into the electrode surface is dissociated and moves through surface diffusion to the three-phase interface (three-phase boundary) where the solid oxide electrolyte 230, the air electrode 220 and the pores (not shown) intersect to obtain electrons to become oxygen ions, and the generated oxygen ions move toward the fuel electrode 210 through the solid oxide electrolyte 230.

[0126] In the fuel electrode 210 of the solid oxide fuel cell 200, the moving oxygen ions combine with hydrogen contained in the fuel to generate water. At this time, hydrogen releases electrons to become hydrogen ions (H + ), hydrogen ion (H + ) is combined with oxygen ions. The released electrons move to the air electrode 220 through a wire (not shown) and change oxygen into oxygen ions. Through this movement of electrons, the solid oxide fuel cell 200 can perform a battery function.

[0127] Figure 5 is a schematic diagram showing an embodiment in which the solid oxide cell 100 is a solid oxide electrolysis cell 300 .

[0128] Reference Figure 5 The solid oxide electrolysis cell 300 includes: an air electrode 310; a fuel electrode 320 disposed facing the air electrode 310; and an oxygen ion conductive solid oxide electrolyte 330 disposed between the air electrode 310 and the fuel electrode 320.

[0129] As shown in Reaction Formula 2, the electrochemical reaction of the solid oxide electrolysis cell 300 includes a fuel electrode reaction and an air electrode reaction. In the fuel electrode reaction, water (H2O) at the fuel electrode 320 is converted into hydrogen (H2) and oxygen ions (O2 - ), in the air electrode reaction, the oxygen ions moving through the solid oxide electrolyte 330 become oxygen (O2). This reaction is opposite to the reaction principle of a conventional fuel cell.

[0130] [Reaction 2]

[0131] Fuel electrode reaction: H2O+2e - →O2 - +H2

[0132] Air electrode reaction: O2 - →1 / 2O2+2e -

[0133] When power is applied to the solid oxide electrolysis cell 300 from the external power supply 340, electrons are supplied to the solid oxide electrolysis cell 300 from the external power supply 340. The electrons react with the water supplied to the fuel electrode 320 to produce hydrogen and oxygen ions. The hydrogen is discharged to the outside, and the oxygen ions reach the air electrode 310 through the electrolyte 330. The oxygen ions moved to the air electrode 310 lose electrons and then become oxygen and are discharged to the outside. The electrons flow to the external power supply 340. Through this electron movement, the solid oxide electrolysis cell 300 can electrolyze water to form hydrogen at the fuel electrode 320 and oxygen at the air electrode 310.

[0134] Figure 6 is a schematic diagram illustrating a method of operating a solid oxide cell 100 according to another embodiment. Figure 6 The case where the solid oxide cell 100 is a solid oxide water electrolysis cell 300 is shown.

[0135] Reference Figure 6 , a method of operating the solid oxide cell 100 includes: supplying a fuel to the fuel electrode 110 ; supplying air to the air electrode 120 ; and supplying dry air directly to the first solid oxide electrolyte layer 131 . Figure 6 The case where the solid oxide cell 100 is a solid oxide electrolysis cell 300 is shown, but when the solid oxide cell 100 is a solid oxide fuel cell 200 , air may not be supplied to the air electrode 120 .

[0136] The dry air may have a relative humidity of about 0% to about 5% at room temperature (25° C.) When the relative humidity of the dry air exceeds about 5%, oxygen ion conductivity of the electrolyte may decrease due to surface adsorption.

[0137] While the present disclosure has been described in conjunction with what are presently considered to be practical example embodiments, it is to be understood that the present disclosure is not limited to the disclosed embodiments, but is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

[0138] <Description of Reference Signs>

[0139] 100: Solid oxide battery

[0140] 105: Cell

[0141] 110: Fuel electrode

[0142] 120: Air electrode

[0143] 130: Solid Oxide Electrolyte

[0144] 131: First solid oxide electrolyte layer

[0145] 132: Second solid oxide electrolyte layer

[0146] 140: Framework

[0147] 141: Window

[0148] 142: Through hole

[0149] 143: First Manifold

[0150] 144: Second manifold

[0151] 145: Third Manifold

[0152] 200: Solid Oxide Fuel Cell

[0153] 210: Fuel electrode

[0154] 220: Air electrode

[0155] 230: Solid Oxide Electrolyte

[0156] 300: Solid oxide electrolysis cell

[0157] 310: Air electrode

[0158] 320: Fuel electrode

[0159] 330: Solid Oxide Electrolyte

[0160] 340: External power supply

[0161] Industrial Applicability

[0162] The present disclosure relates to a solid oxide cell and an operating method thereof, wherein the gas separation function of the solid oxide electrolyte can be maintained while ensuring the ductility of the material to improve mechanical properties and long-term reliability, and the cell performance and efficiency of the solid oxide cell can be improved by improving oxygen ion conductivity.

Claims

1. A solid oxide battery comprising: A unit cell, the unit cell comprising: a solid oxide electrolyte, the solid oxide electrolyte comprising a first solid oxide electrolyte layer and a second solid oxide electrolyte layer, the second solid oxide electrolyte layer being disclosed on one surface or both surfaces of the first solid oxide electrolyte layer and having a density higher than that of the first solid oxide electrolyte layer; a fuel electrode disposed on one surface of the solid oxide electrolyte; and an air electrode disposed on an opposite surface of the solid oxide electrolyte; A frame has a first manifold and surrounds the respective side surfaces of the unit cells, and air supplied to the first solid oxide electrolyte layer flows through the first manifold.

2. The solid oxide battery according to claim 1, wherein: The air is dry air with a relative humidity of 0% to 5%.

3. The solid oxide battery according to claim 1, wherein: The first manifold penetrates the frame in a thickness direction of the frame, the thickness direction being perpendicular to the surface of the first solid oxide electrolyte layer of the unit cell.

4. The solid oxide battery according to claim 1, wherein: The frame has a window to accommodate the unit cells and a plurality of through holes connecting the window and the first manifold.

5. The solid oxide battery according to claim 1, wherein: The frame also has a second manifold through which fuel supplied to the fuel electrode flows and a third manifold through which air supplied to the air electrode flows.

6. The solid oxide battery according to claim 5, wherein: The frame has a window to accommodate the unit cells and a through hole to connect the window and the third manifold.

7. The solid oxide battery according to claim 4, wherein: The solid oxide cell supplies air to the air electrode through the first manifold.

8. The solid oxide battery according to claim 1, further comprising: a first separator disposed on one surface of the unit cell and having a flow path for supplying a fuel to a surface of the first separator facing the fuel electrode; as well as A second separator is disposed on an opposite surface of the unit cell and has a flow path for supplying air to a surface of the second separator facing the air electrode.

9. The solid oxide battery according to claim 8, wherein: The frame and at least one of the first partition or the second partition are integrated with each other.

10. The solid oxide battery according to claim 1, wherein: The second solid oxide electrolyte layer has a density greater than or equal to about 90%, and The first solid oxide electrolyte layer has a density level less than or equal to about 75%.

11. The solid oxide battery according to claim 1, wherein: The second solid oxide electrolyte layer has an average thickness of less than or equal to about 10 μm, and The first solid oxide electrolyte layer has an average thickness greater than or equal to about 2 μm.

12. The solid oxide battery according to claim 1, wherein: The first solid oxide electrolyte layer or the second solid oxide electrolyte layer includes at least one of yttria-stabilized zirconia (YSZ), scandia-stabilized zirconia (ScSZ), gadolinium oxide-doped ceria (GDC), samarium oxide-doped ceria (SDC), strontium and magnesium-doped lanthanum gallate (LSGM), barium zirconate doped with samarium oxide and ceria (BaZrO3), barium ceria doped with samarium oxide and ceria (BaCeO3), bismuth oxide (Bi2O3) or a combination thereof.

13. The solid oxide battery according to claim 12, wherein: The first solid oxide electrolyte layer includes yttria-stabilized zirconia (YSZ), scandia-stabilized zirconia (ScSZ), or a combination thereof.

14. The solid oxide battery according to claim 12, wherein: The second solid oxide electrolyte layer includes gadolinium oxide-doped ceria (GDC), samarium oxide-doped ceria (SDC), or a combination thereof.

15. The solid oxide battery according to claim 1, wherein: The solid oxide cell is a solid oxide fuel cell (SOFC), a solid oxide electrolyzer (SOEC), or both.

16. A method of operating a solid oxide cell, the method comprising: preparing a solid oxide cell, the solid oxide cell comprising a unit cell, the unit cell comprising: a solid oxide electrolyte, the solid oxide electrolyte comprising a first solid oxide electrolyte layer and a second solid oxide electrolyte layer, the second solid oxide electrolyte layer being disclosed on one surface or both surfaces of the first solid oxide electrolyte layer and having a density higher than that of the first solid oxide electrolyte layer; supplying a fuel to the fuel electrode; and Dry air is supplied to the first solid oxide electrolyte layer.

17. The method according to claim 16, wherein: The dry air has a relative humidity of about 0% to about 5%.

18. The method according to claim 16, wherein: Air is supplied to the air electrode.

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