Solid oxide composite and method for producing same

Abstract

A solid oxide composite according to the present disclosure includes: a solid oxide electrolyte including pores; and an oxide-based electrode active material in the hole.

Description

Technical Field

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

[0002] Solid oxide fuel cells (SOFCs) and solid oxide electrolysis cells (SOECs) generate electrical energy or electrolyze water through the electrochemical reaction of a unit composed of an air electrode, a fuel electrode, and a solid electrolyte having oxygen ion conductivity, and generate hydrogen through the reverse reaction of the solid oxide fuel cell. The unit has a structure in which the air electrode and the fuel electrode are respectively disposed on both sides of a solid electrolyte having oxygen ion conductivity. Air and hydrogen are respectively supplied to the air electrode and the fuel electrode through gas flow paths formed in a separator to perform an electrochemical reaction, thereby generating electricity or performing electrolysis.

[0003] In order to improve the overall performance (such as output characteristics, etc.) of solid oxide fuel cells, active research is being conducted on electrode materials included in the air electrode and the fuel electrode. Therefore, electrode materials tend to be mixed with the electrolyte rather than used alone, but typical conventional processes that simply physically mix separately synthesized electrode materials with the electrolyte have been used. However, there is a problem of insufficient number of triple phase boundaries (TPBs) that are effective reaction sites where electrode particles and electrolyte particles meet. Summary of the Invention

[0004]

Technical Problem

[0005] Another aspect of the present embodiment provides a method for manufacturing a solid oxide composite.

[0006] Another aspect of the embodiment provides a solid oxide fuel cell that includes the solid oxide composite to promote the electrochemical reaction of the unit, thereby improving the output characteristics of the cell and having excellent degradation stability even under high-temperature operating conditions.

[0007] Another aspect of the embodiment provides a solid oxide electrolysis cell that includes the solid oxide composite to improve the output characteristics of the unit by accelerating the electrochemical reaction of the unit and having excellent degradation stability even under high-temperature operating conditions.

[0008] However, the problems to be solved by the embodiment are not limited to the above problems, and various expansions can be made within the scope of the technical idea included in the embodiment.

[0009]

Technical Solution

[0010] The pores of the solid oxide electrolyte may have an inverse helical structure.

[0011] The average size of the pores may be from 2 nm to 50 nm.

[0012] The BET specific surface area of the solid oxide composite may be 5 m 2 / g to 200 m 2 / g.

[0013] Based on the total volume of the pores, the oxide-based electrode active material may be included in an amount of 20 vol% to 95 vol%.

[0014] The weight ratio of the solid oxide electrolyte to the oxide-based electrode active material may be from 40:60 to 60:40.

[0015] The solid oxide electrolyte may include YSZ (yttria-stabilized zirconia), ScSZ (scandia-stabilized zirconia), GDC (gadolinium-doped ceria), SDC (samarium-doped ceria), LSGM (lanthanum strontium gallium magnesium oxide), or a combination thereof.

[0016] The oxide-based electrode active material may include a fuel electrode active material, and the fuel electrode active material may include nickel oxide (NiO).

[0017] The oxide-based electrode active material may include an air electrode active material, and the air electrode active material may include lanthanum strontium manganite (LSM), lanthanum strontium ferrite (LSF), lanthanum strontium cobaltite (LSC), lanthanum strontium cobalt ferrite (LSCF), samarium strontium cobaltite (SSC), barium strontium cobalt ferrite (BSCF), bismuth ruthenate, or a combination thereof.

[0018] A method of manufacturing a solid oxide composite according to another embodiment includes filling first pores of a silica template with a solid oxide electrolyte; removing the silica template with an alkaline solution to prepare a solid oxide electrolyte including second pores; and filling the second pores of the solid oxide electrolyte with the oxide-based electrode active material.

[0019] Filling the first pores of the silica template with the solid oxide electrolyte may include a first process of filling the first pores of the silica template with a portion of the solid oxide electrolyte precursor and a second process of filling the first pores of the silica template with the remaining solid oxide electrolyte precursor. A weight ratio of the solid oxide electrolyte precursor filled in the first pores in the first process to the solid oxide electrolyte precursor added to the first pores in the second process may be 1.5:1 to 3:1.

[0020] Filling the second pores of the solid oxide electrolyte with the oxide-based electrode active material may be repeated 1 to 5 times.

[0021] The silica template may include MCM-41, MCM-48, MCM-50, SBA-11, SBA-12, SBA-15, SBA-16, KIT-5, KIT-6, FDU-2, or COK-12.

[0022] The first pore of the silica template may have a spiral structure.

[0023] The first pores of the solid oxide electrolyte may have an inverse pore structure of the silica template.

[0024] The first pore of the solid oxide electrolyte may have a reverse spiral structure.

[0025] A solid oxide fuel cell according to another embodiment includes an air electrode; a solid oxide electrolyte layer; and a fuel electrode, wherein the fuel electrode or the air electrode includes the solid oxide composite.

[0026] A solid oxide electrolysis cell according to another embodiment includes an air electrode, a solid oxide electrolyte layer, and a fuel electrode. The fuel electrode or the air electrode may include the solid oxide composite.

[0027] A solid oxide composite according to an embodiment includes: an oxide-based electrode active material including pores; and a solid oxide electrolyte in the pores.

[0028] The solid oxide composite according to the embodiment includes a solid oxide electrolyte and an oxide-based electrode active material. One of the solid oxide electrolyte and the oxide-based electrode active material includes a plurality of pores, and the other of the solid oxide electrolyte and the oxide-based electrode active material is disposed in the plurality of pores, so that the solid oxide electrolyte and the oxide-based electrode active material are staggered.

[0029] The solid oxide composite according to the embodiment has electrode particles and electrolyte particles in nano-unit contact to have a very large effective reaction area, thereby promoting the electrochemical reaction of the cell to improve the output characteristics of the battery, and having the advantage of very high degradation stability even under high-temperature operating conditions. Description of the Drawings

[0030] Figure 1 is a schematic diagram schematically showing the solid oxide composite according to the embodiment.

[0031] Figure 2 is a schematic diagram schematically showing KIT-6, which is a silica template.

[0032] Figure 3 is a schematic cross-sectional view of a solid oxide fuel cell according to the embodiment.

[0033] Figure 4 is a transmission electron microscope (TEM) photograph of YSZ, which is a solid oxide electrolyte including pores.

[0034] Figure 5 shows the results of BET analysis of the YSZ solid oxide electrolyte including pores and the solid oxide composites of Preparation Examples 1-1 to 1-4.

[0035] Figure 6 shows the results of BET analysis of the solid oxide composite of Preparation Example 2-2.

[0036] Figure 7 shows the results of BET specific surface area analysis of the YSZ solid oxide electrolyte including pores and the solid oxide composites of Preparation Examples 1-1 to 1-4.

[0037] Figure 8 shows the results of analyzing the BET specific surface area of the solid oxide composite of Preparation Example 2-2.

[0038] Figure 9 shows the results of measuring the power density of solid oxide fuel cells respectively including NiO-YSZ prepared in Preparation Example 1-3 and Comparative Preparation Example 1-5 in the fuel electrode.

[0039] Figure 10 shows the results of measuring the power density of solid oxide fuel cells respectively including LSM-YSZ prepared in Preparation Example 2-2 and Comparative Preparation Example 2-3 in the air electrode. Detailed Description of the Invention

[0040] Hereinafter, various embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art to which the present invention pertains can practice it. The drawings and the description are considered illustrative rather than restrictive in nature. Throughout the specification, the same reference numerals denote the same elements. In addition, the drawings are provided only for facilitating the understanding of the embodiments disclosed in this specification and should not be construed as limiting the spirit disclosed in this specification, and it should be understood that the present invention includes all variations, equivalents, and alternatives without departing from the scope and spirit of the present invention. In addition, some components in the drawings are exaggerated, omitted, or shown schematically, and the dimensions of each component do not fully reflect the actual dimensions.

[0041] In addition, unless explicitly described to the contrary, the word "comprising" and variations such as "including" or "containing" will be understood to imply including the stated elements but not excluding any other elements.

[0042] Hereinafter, various embodiments and variations will be described in detail with reference to the accompanying drawings.

[0043] Solid oxide composite Referring to Figure 1 , the solid oxide composite 1 according to the embodiment includes a solid oxide electrolyte 2 including pores and an oxide-based electrode active material 3 in the pores.

[0044] Since the oxide-based electrode active material 3 can contact the solid oxide electrolyte 2 in nanometer units of about 10 nm or less, the solid oxide composite 1 can have a large number of triple-phase boundaries (TPBs), which are effective reaction regions. Therefore, it has the advantages of not only promoting the electrochemical reaction of the cell, improving the output characteristics of the battery, but also maintaining many triple-phase boundaries (TPBs) under high-temperature operating conditions and greatly increasing the degradation stability.

[0045] Different from the solid oxide composite according to the embodiment, in a conventional solid oxide composite prepared by simply physically mixing a solid oxide electrolyte and an oxide-based electrode active material, since the solid oxide electrolyte and the oxide-based electrode active material grow independently, this increases the particle size and makes it difficult to ensure the triple-phase boundary (TPB), so it is difficult to sufficiently ensure the electron and ion transfer paths.

[0046] In the embodiment, the pores of the solid oxide electrolyte can be a reverse pore structure of a silica template. For example, the pores of the solid oxide electrolyte can be a reverse spiral structure.

[0047] The silica template may include MCM-41, MCM-48, MCM-50, SBA-11, SBA-12, SBA-15, SBA-16, KIT-5, KIT-6, FDU-2, or COK-12. For example, referring toFigure 2 , the silica template can be KIT-6.

[0048] For example, the average pore size can be from 2 nm to 50 nm. For example, the average pore size can be from 2 nm to 20 nm, or from 2 nm to 10 nm.

[0049] The average pore size can be measured as follows: Sampling a solid oxide composite from the electrode of a solid oxide fuel cell or the solid oxide electrolyzer itself, fabricating a sample with a thickness of about 100 nm or less, and then taking a transmission electron microscope (TEM) photograph thereof. The TEM photograph can be measured as follows: Adjusting the contrast in a method such as binarizing the image to define the relatively dark regions as the solid oxide electrolyte and the relatively bright regions as the oxide-based electrode active material. In this article, the distances between the dark regions at 10 or more points can be measured and then averaged to calculate the average pore size.

[0050] For example, the BET specific surface area of the solid oxide composite can be 5 m 2 / g to 200 m 2 / g. For example, the BET specific surface area of the solid oxide composite can be 5 m 2 / g to 100 m 2 / g, for example 5 m 2 / g to 50 m 2 / g or 10 m 2 / g to 40 m 2 / g. When the solid oxide composite satisfies the BET specific surface area within the above range, a solid oxide composite with easy electron transfer can be achieved while ensuring a large number of triple-phase boundaries (TPBs) as effective reaction sites.

[0051] BET (Brunauer Emmett Teller gas adsorption method) measurement is a method for measuring specific surface area, pore size, and pore size distribution by adsorbing a gas (e.g., nitrogen) to / desorbing a gas (e.g., nitrogen) from a sample. BET (gas adsorption method) measurement can be used to calculate the specific surface area on the surface of a sample by using the volume change of the adsorbed gas according to the pressure change. In addition, the correlation coefficient representing the degree of agreement between the straight line and the C value (BET constant) can be analyzed to evaluate the reliability, and the C value is the y-intercept of the BET plot, and the BET plot is a graph of the volume of the adsorbed gas versus the relative pressure. Specifically, the shape of the pores present in the sample can be predicted from the curve shape of the BET plot. For example, when hysteresis occurs where the adsorption line and the desorption line do not match in the BET plot, it can be predicted that the sample has pores.

[0052] For example, based on the total volume of the pores, an oxide-based electrode active material may be included in an amount of 20% to 95% by volume. For example, based on the total volume of the pores, a fuel electrode active material may be included in an amount of 40% to 80% by volume, or 50% to 80% by volume. If the above ranges are satisfied, a solid oxide composite with easy electron transfer can be achieved while ensuring a large number of triple-phase boundaries (TPBs) as effective reaction sites.

[0053] The weight ratio of the solid oxide electrolyte to the oxide-based electrode active material may be from 40:60 to 60:40. If the weight ratio within the above range is satisfied, a solid oxide composite with easy electron transfer can be achieved while ensuring a large number of triple-phase boundaries (TPBs) as effective reaction sites.

[0054] In an embodiment, the solid oxide electrolyte can be used without limitation as long as it is commonly used.

[0055] For example, the solid oxide electrolyte may include at least one selected from the following: zirconia-based solid electrolytes doped or undoped with at least one of yttrium, scandium, calcium, and magnesium; ceria-based solid electrolytes doped or undoped with at least one of gadolinium, samarium, lanthanum, ytterbium, and neodymium; bismuth oxide-based solid electrolytes doped or undoped with at least one of calcium, strontium, barium, gadolinium, and yttrium; and lanthanum gallate-based solid electrolytes doped or undoped with at least one of strontium and magnesium.

[0056] For example, it may include YSZ (yttria-stabilized zirconia), ScSZ (scandia-stabilized zirconia), GDC (gadolinium-doped ceria), SDC (samarium-doped ceria), LSGM (lanthanum-strontium-gallium-magnesium oxide), or a combination thereof.

[0057] The oxide-based electrode active material may include a fuel electrode active material, an air electrode active material, or both.

[0058] The fuel electrode active material can be any commonly used material without limitation. For example, the fuel electrode active material may include nickel (Ni), cobalt (Co), ruthenium (Ru), palladium (Pd), platinum (Pt), their oxides, or a combination thereof, such as nickel oxide (NiO).

[0059] The air electrode is not particularly limited as long as it is commonly used in the prior art. For example, the air electrode may include metal oxide particles having a perovskite-type crystal structure. Perovskite-type metal oxides are mixed ionic and electronic conductor (MIEC) materials having both ionic conductivity and electronic conductivity, and have a high oxygen diffusion coefficient and charge exchange reaction rate coefficient, so that the oxygen reduction reaction can occur on the entire surface of the electrode rather than only at the triple phase boundary, which can improve the electrode activity at low temperatures and thus contribute to reducing the operating temperature of the SOFC.

[0060] The perovskite-type metal oxide can be represented by Chemical Formula 1.

[0061] [Chemical Formula 1] ABO 3±δ In Chemical Formula 1, A is at least one element selected from La, Ba, Sr, Sm, Gd, and Ca, B is at least one element selected from Mn, Fe, Co, Ni, Cu, Ti, Nb, Cr, and Sc, and δ represents the excess or deficiency of oxygen.

[0062] δ can be, for example, in the range of 0 ≤ δ ≤ 0.3.

[0063] For example, the perovskite-type metal oxide can be represented by Chemical Formula 2.

[0064] [Chemical Formula 2] A’ 1-x A” x B’O 3±γ In Chemical Formula 2, A’ is at least one element selected from Ba, La, and Sm, A” is at least one element selected from Sr, Ca, and Ba and different from A’, and B’ is at least one element selected from Mn, Fe, Co, Ni, Cu, Ti, Nb, Cr, and Sc, 0 ≤ x < 1, and γ represents the excess or deficiency of oxygen.

[0065] γ can be, for example, in the range of 0 ≤ γ ≤ 0.3.

[0066] Examples of such perovskite-type metal oxides may include barium strontium cobalt iron oxide (BSCF), lanthanum strontium cobalt oxide (LSC), lanthanum strontium cobalt iron oxide (LSCF), lanthanum strontium cobalt manganese oxide (LSCM), lanthanum strontium iron oxide (LSF), samarium strontium cobalt oxide (SSC), etc.

[0067] Specifically, the perovskite-type metal oxide may include Ba 1-x Sr x Co 1-y Fe y O3 (where 0.1 ≤ x ≤ 0.5, 0.05 ≤ y ≤ 0.5), Baa Sr b Co x Fe y Z 1-x-y O 3±γ (wherein, Z is at least one element selected from transition metal elements and lanthanide elements, 0.4 ≤ a ≤ 0.6, 0.4 ≤ b ≤ 0.6, 0.6 ≤ x ≤ 0.9, 0.1 ≤ y ≤ 0.4), La 1-x Sr x Fe 1-y Co y O 3±γ (wherein 0.1 ≤ x ≤ 0.4, 0.05 ≤ y ≤ 0.5), Sm 1-x Sr x CoO3 (wherein 0.1 ≤ x ≤ 0.5), etc. For example, perovskite-type metal oxides may include oxides such as Ba 0.5 Sr 0.5 Co 0.8 Fe 0.2 O 3±γ 、Ba 0.5 Sr 0.5 Co 0.8 Fe 0.1 Z 0.1 O 3±γ (wherein, Z is Mn, Zn, Ni, Ti, Nb, or Cu), La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3±γ 、Sm 0.5 Sr 0.5 CoO3, etc. These perovskite-type metal oxides can be used alone or in combination of two or more.

[0068] As a specific example, the air electrode active 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 a combination thereof.

[0069] Method for manufacturing a solid oxide composite The method for manufacturing a solid oxide composite according to the embodiment includes filling pores of a silica template with a solid oxide electrolyte; removing the silica template with an alkaline solution to prepare a solid oxide electrolyte including pores; and filling the pores of the solid oxide electrolyte with an oxide-based electrode active material.

[0070] In an embodiment, filling the pores of the silica template with a solid oxide electrolyte may include a first process of filling the pores of the silica template with a portion of the solid oxide electrolyte precursor and a second process of filling the pores of the silica template with the remaining solid oxide electrolyte precursor.

[0071] The weight ratio of the solid oxide electrolyte precursor filled in the pores in the first process to the solid oxide electrolyte precursor added to the pores in the second process may be from 1.5:1 to 3:1.

[0072] As described above, when filling the pores in two steps, the pores can be filled uniformly while minimizing the amount of the solid oxide electrolyte precursor accumulated around the silica template.

[0073] Removing the silica template with an alkaline solution to prepare a solid oxide electrolyte including pores employs an alkali etching method, in which the silica template is removed (etched) by using an alkaline solution.

[0074] The alkaline solution can use any solution used in the prior art without limitation. For example, the alkaline solution may include an aqueous sodium hydroxide solution (NaOH) or an aqueous potassium hydroxide solution (KOH).

[0075] Filling the pores of the solid oxide electrolyte with an oxide-based electrode active material can be repeated one to five times, for example, three to four times, for example, three times.

[0076] When filling the pores of the solid oxide electrolyte with the oxide-based electrode active material is overly repeated, the ratio of the solid oxide electrolyte to the oxide-based electrode active material may be unbalanced, such that the oxide-based electrode active material or the solid oxide electrolyte may not be properly connected, resulting in an insufficient electron transfer path.

[0077] When filling the pores of the solid oxide electrolyte with the oxide-based electrode active material is repeated a certain number of times, a solid oxide composite with easy electron transfer can be prepared while ensuring a large number of triple-phase boundaries (TPBs) as effective reaction sites.

[0078] The silica template may include MCM-41, MCM-48, MCM-50, SBA-11, SBA-12, SBA-15, SBA-16, KIT-5, KIT-6, FDU-2, or COK-12. For example, referring to Figure 2 , the silica template can be KIT-6.

[0079] The pores of the silica template can be interpenetrating bicontinuous pores. For example, the pores of the silica template can be a gyroid structure.

[0080] The helical structure is a three-dimensional structure in which two independent pores are connected three-dimensionally and an infinite surface is maintained at regular intervals. The helical structure has regularly arranged pores (pore size of about 10 nm) and has a large surface area.

[0081] For example, the pores of the solid oxide electrolyte can be the reverse pore structure of a silica template. For example, the pores of the solid oxide electrolyte can be a reverse helical structure. The reason is that when the silica template is removed after filling the pores of the silica template with the solid oxide electrolyte, the pores of the solid oxide electrolyte have the reverse shape of the silica template pores.

[0082] Solid oxide fuel cell and solid oxide electrolytic cell Figure 3 is a cross-sectional view schematically showing the structure of a solid oxide fuel cell (SOFC) according to an embodiment. Referring to Figure 3 , the solid oxide fuel cell 10 includes: an air electrode 11; a solid oxide electrolyte layer 12; and a fuel electrode 13. The fuel electrode 13 or the air electrode 11 includes the aforementioned solid oxide composite.

[0083] A solid oxide electrolysis cell (SOEC) according to another embodiment includes: an air electrode; a solid oxide electrolyte layer; and a fuel electrode. The fuel electrode or the air electrode includes the aforementioned solid oxide composite.

[0084] The solid oxide composite may include a solid oxide electrolyte containing pores and an oxide-based electrode active material in the pores.

[0085] Since the materials of the solid oxide composite, the solid oxide electrolyte including pores, and the electrodes (air electrode, fuel electrode) are the same as those described in detail above, their descriptions are omitted.

[0086] By including the aforementioned solid oxide composite in the air electrode, fuel electrode, or both of the electrodes included in the solid oxide fuel cell and the solid oxide electrolysis cell, the electrochemical reaction of the unit is promoted to improve the output characteristics of the battery and achieve a battery and unit with very high degradation stability even under high-temperature operating conditions.

[0087] In SOFC and SOEC, only ions and electrons move in opposite directions, and the air electrode, solid oxide electrolyte layer, and fuel electrode constituting the unit are the same. Hereinafter, the solid oxide fuel cell (SOFC) will be described in detail. In addition to the descriptions described above, the structure of the unit will be described in detail.

[0088] The air electrode 11 reduces oxygen (O2) to produce oxygen ions (O 2-), air is continuously supplied to the air electrode 11 to maintain a constant oxygen partial pressure. The generated oxygen ions move toward the solid oxide electrolyte layer 12.

[0089] The air electrode 11 may have a thickness of 1 μm to 100 μm. For example, the thickness of the first air electrode 11 may be 5 μm to 50 μm.

[0090] It is desirable for the air electrode 11 to have a porosity that allows oxygen to diffuse well therein.

[0091] The solid oxide electrolyte layer 12 is used to transport the oxygen ions generated in the air electrode 11 to the fuel electrode 13 through ionic conduction. The solid oxide electrolyte layer 12 has airtightness to block the contact between the air electrode and the fuel electrode, and has high oxygen ion conductivity and low electron conductivity (high resistance, high insulation), so that the electrons generated from the fuel electrode can be blocked from directly moving to the air electrode.

[0092] In addition, since the air electrode 11 and the fuel electrode 13 with a very large oxygen partial pressure difference are on both sides of the solid oxide electrolyte layer 12, it may be necessary to maintain the above properties in a wide oxygen partial pressure range.

[0093] The material constituting the solid oxide electrolyte layer 12 is not particularly limited as long as it can be commonly used in the art, and may include at least one selected from, for example, zirconia-based solid electrolytes, ceria-based solid electrolytes, bismuth oxide-based solid electrolytes, and lanthanum gallate-based solid electrolytes.

[0094] For example, the solid oxide electrolyte layer 12 may be a zirconia-based solid electrolyte doped or undoped with at least one of yttrium, scandium, calcium, and magnesium; a ceria-based solid electrolyte doped or undoped with at least one of gadolinium, samarium, lanthanum, ytterbium, and neodymium; a bismuth oxide-based solid electrolyte doped or undoped with at least one of calcium, strontium, barium, gadolinium, and yttrium; and at least one of lanthanum gallate-based solid electrolytes doped or undoped with at least one of strontium and magnesium. Specific examples of the materials included in the solid oxide electrolyte layer 12 may include yttria-stabilized zirconia (YSZ), scandia-stabilized zirconia (ScSZ), samarium-doped ceria (SDC), gadolinium-doped ceria (GDC), etc.

[0095] The thickness of the solid oxide electrolyte layer 12 is generally 10 nm to 100 μm. For example, the thickness of the solid oxide electrolyte layer 12 may be 100 nm to 50 μm.

[0096] The fuel electrode 13 is used for electrochemically oxidizing fuel and transferring charge. The fuel electrode 13 can be used to produce H2O by reacting hydrogen supplied from the outside with oxygen ions transported from the solid oxide electrolyte layer 12. In this process, electrons are generated, and the generated electrons can move toward the air electrode 11 through the load.

[0097] In addition to the solid oxide composite, the fuel electrode 13 may further include fuel electrode active materials that can generally be used in the art. For example, it may include NiO-YSZ, NiO-ScSZ, NiO-GDC, NiO-SDC, BaZrO3 doped with NiO, Ru, Pd, Rd, or Pt.

[0098] The fuel electrode 13 may have a thickness of 1 μm to 1000 μm. For example, the fuel electrode 13 may have a thickness of 5 μm to 100 μm.

[0099] According to an embodiment, the solid oxide fuel cell 10 further includes an electric collection layer (not shown), which includes an electron conductor on at least one side surface of the air electrode 11, for example, the outer side surface of the air electrode 11.

[0100] The electric collection layer can be used as a current collector to collect electric power in the structure of the air electrode.

[0101] The electric collection layer may include at least one of, 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), and lanthanum strontium iron oxide (LSF). The electric collection layer can be used alone with the materials listed above or in combination of two or more. These materials can be formed into a single layer or two or more layers having a stacked structure.

[0102] The solid oxide cell can be manufactured by conventional methods known in various literatures in the art. The solid oxide cell can be applied to various structures, such as a cylindrical (tubular) stacked structure, a flat tubular stacked structure, a planar stacked structure, etc.

[0103] Hereinafter, specific examples of the present invention are presented. However, the examples described below are only intended to specifically illustrate or explain the present invention, and the scope of the present invention should not be limited thereto.

[0104] [Preparation Example] (Preparation Example 1-1: Preparation of Solid Oxide Composite NiO-YSZ 1) 3.2 g of a YSZ precursor prepared by mixing 3.029 g of ZrOCl2·8H2O and 0.171 g of Y(NO3)3·6H2O was mixed with a mixed solvent of 15 mL of ethanol and 5 mL of water. Thus, a primary precursor slurry was prepared.

[0105] After mixing the primary precursor slurry with 1.2 g of silica template KIT-6, the solvent was evaporated in a Petri dish at 70 °C. After all the solvent had been evaporated, the residue was fired to 350 °C and then held at the maximum temperature for 4 hours. Thus, the primary product was prepared.

[0106] 1.6 g of YSZ precursor prepared by mixing 1.5145 g of ZrOCl2·8H2O and 0.0855 g of Y(NO3)3·6H2O was mixed in a mixed solvent of 7.5 ml of ethanol and 2.5 ml of water. Thus, the secondary precursor slurry was prepared.

[0107] After mixing the secondary slurry with the primary product, the solvent was evaporated in a Petri dish at 70 °C. After all the solvent had been evaporated, the residue was fired to 550 °C and then held at the maximum temperature for 4 hours. Thus, the secondary product was prepared.

[0108] The secondary product was fired to 650 °C at 2 °C / min within 5 hours and 10 minutes, and then the final firing was carried out (held at the maximum temperature for 2 hours).

[0109] The prepared secondary product was placed in 1.33 g of 1 M aqueous NaOH solution (prepared by mixing 200 ml of water and 8 g of NaOH) and held at 90 °C for 2 hours, and then placed again in 2.45 g of the same 1 M aqueous NaOH solution and held at 90 °C for 2 hours to remove KIT-6.

[0110] Figure 4 The YSZ solid oxide electrolyte including pores (average pore diameter: 10 nm) produced after removing KIT-6 is shown.

[0111] 3.5 g of Ni(NO3)2·6H2O as the NiO fuel electrode precursor was mixed with a mixed solvent of 15 mL of ethanol and 5 mL of water to prepare the fuel electrode slurry. Then, the fuel electrode slurry was coated on the YSZ solid oxide electrolyte at one time to fabricate the solid oxide composite NiO-YSZ 1.

[0112] (Preparation Example 1-2: Preparation of Solid Oxide Composite NiO-YSZ 2) The solid oxide composite NiO-YSZ 2 was prepared in the same manner as Preparation Example 1, except that the fuel electrode slurry coating process in Preparation Example 1-1 was repeated twice.

[0113] (Preparation Example 1-3: Preparation of Solid Oxide Composite NiO-YSZ 3) Except for repeating the fuel electrode paste coating process in Preparation Example 1-1 three times, solid oxide composite NiO-YSZ 3 was prepared in the same manner as in Preparation Example 1.

[0114] (Preparation Example 1-4: Preparation of solid oxide composite NiO-YSZ 4) Except for repeating the fuel electrode paste coating process in Preparation Example 1-1 four times, solid oxide composite NiO-YSZ 4 was prepared in the same manner as in Preparation Example 1.

[0115] (Comparative Preparation Example 1-5) A solid oxide composite NiO-YSZ was prepared by a simple physical mixing method.

[0116] (Preparation Example 2-1: Preparation of solid oxide composite LSM-YSZ 1) Except for mixing 3.5 g of LSM air electrode precursor including La(NO3)3·6H2O, Sr(NO3)2·4H2O, and Mn(NO3)2·6H2O with a mixed solvent of 15 mL of ethanol and 5 mL of water to prepare an air electrode paste, and coating the YSZ solid oxide electrolyte according to Preparation Example 1-1 with the air electrode paste, solid oxide composite LSM-YSZ 1 was prepared in the same manner as in Preparation Example 1-1.

[0117] (Preparation Example 2-2: Preparation of solid oxide composite LSM-YSZ 3) Except for repeating the air electrode paste coating process in Preparation Example 2-1 three times, solid oxide composite LSM-YSZ 3 was prepared in the same method as in Preparation Example 2-1.

[0118] (Comparative Preparation Example 2-3) A solid oxide composite LSM-YSZ was prepared by a simple physical mixing method.

[0119] [Experimental Example] (Experimental Example 1: BET analysis of solid oxide composites) BET analysis was performed on the solid oxide electrolyte YSZ including pores and solid oxide composites NiO-YSZ 1 to 4 (Preparation Examples 1-1 to 1-4), and the results are shown in Figure 5 .

[0120] In addition, BET analysis was performed on the solid oxide composite LSM-YSZ 3 (Preparation Example 2-2), and the results are shown in Figure 6 .

[0121] In Figure 5 and Figure 6In this case, the horizontal axis represents the size of the pores, and the vertical axis represents the volume of the pores. Figure 5 It is shown that the volume of the pores decreases according to the number of coating times of the fuel electrode active material, and Figure 5 and Figure 6 it is shown that the pores exhibit a size distribution of about 10 nm or less. Therefore, the pores generated in the solid oxide composite have an average size of about 10 nm or less.

[0122] (Experimental Example 2: BET Specific Surface Area Analysis of Solid Oxide Composites) The BET specific surface areas of the solid oxide electrolyte YSZ and the solid oxide electrolytes NiO-YSZ 1 to 4 (Preparation Examples 1-1 to 1-4) including pores were analyzed, and the results are shown in Figure 7 this figure.

[0123] In addition, the BET specific surface area of the solid oxide composite LSM-YSZ 3 (Preparation Example 2-2) was analyzed, and the results are shown in Figure 8 this figure.

[0124] Referring to Figure 7 and Figure 8 this figure, since all the curves confirm the hysteresis phenomenon where the adsorption curve and the desorption curve do not match, both the solid oxide composites NiO-YSZ 1 to 4 and the solid oxide composite LSM-YSZ 3 include pores.

[0125] (Experimental Example 3: Analysis of Electrical Characteristics of Solid Oxide Fuel Cells) Each solid oxide fuel cell was fabricated to include NiO-YSZ 3 of Preparation Example 1-3 and NiO-YSZ of Comparative Preparation Example 1-5 in each fuel electrode, and then the power density was measured, and the results are shown in Figure 9 this figure.

[0126] In addition, each solid oxide fuel cell was fabricated to include LSM-YSZ 3 of Preparation Example 2-2 and LSM-YSZ of Comparative Preparation Example 2-3 in each air electrode, and then the power density was measured, and the results are shown in Figure 10 this figure.

[0127] A solid oxide fuel cell including the solid oxide composite NiO-YSZ 3 according to the embodiment in each fuel electrode or a solid oxide fuel cell including the solid oxide composite LSM-YSZ 3 in each fuel electrode has a triple-phase boundary (TPB) as a very large effective reaction area because the electrode particles and the electrolyte particles can contact each other in nanometer units of about 10 nm or less, and thus promotes the electrochemical reaction, thereby improving the output characteristics.

[0128] On the other hand, a solid oxide fuel cell including NiO-YSZ prepared by simply mixing in a fuel electrode or LSM-YSZ prepared by simply mixing in an air electrode cannot ensure a triple-phase boundary (TPB) because the solid oxide electrolyte and the oxide-based electrode active material grow independently, and thus cannot sufficiently ensure an electron transfer path, showing relatively poor output characteristics.

[0129] Although the present invention has been described in connection with what is presently considered to be practical example embodiments, it should be understood that the present invention is not limited to the disclosed embodiments. On the contrary, it is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

[0130] 《Industrial Applicability》 The present disclosure relates to a solid oxide fuel cell (SOFC) or a solid oxide electrolytic cell (SOEC) that improves the output characteristics of the cell by accelerating the electrochemical reaction of the unit, and has excellent degradation stability even under high-temperature operating conditions, and can be used in various electrochemical devices and electronic devices.

[0131] <Description of Reference Numerals> 1: Solid oxide composite 2: Solid oxide electrolyte 3: Oxide-based electrode active material 10: Solid oxide fuel cell 11: Air electrode 12: Solid oxide electrolyte layer 13: Fuel electrode

Claims

1. A solid oxide composite, comprising: A solid oxide electrolyte, including pores; and an oxide-based electrode active material, within the pores.

2. The solid oxide composite according to claim 1, wherein, The pores of the solid oxide electrolyte have a reverse helical structure.

3. The solid oxide composite according to claim 1, wherein, The average size of the pores is from 2 nm to 50 nm.

4. The solid oxide composite according to claim 1, wherein, The BET specific surface area of the solid oxide composite is 5 m 2 / g to 200 m 2 / g.

5. The solid oxide composite according to claim 1, wherein, Based on the total volume of the pores, the oxide-based electrode active material is included in an amount of 20 vol% to 95 vol%.

6. The solid oxide composite according to claim 1, wherein, The weight ratio of the solid oxide electrolyte to the oxide-based electrode active material is from 40:60 to 60:

40.

7. The solid oxide composite according to claim 1, wherein, The solid oxide electrolyte includes YSZ (yttria-stabilized zirconia), ScSZ (scandia-stabilized zirconia), GDC (gadolinium-doped ceria), SDC (samarium-doped ceria), LSGM (lanthanum strontium gallium magnesium oxide), or a combination thereof.

8. The solid oxide composite according to claim 1, wherein, The oxide-based electrode active material includes a fuel electrode active material, and the fuel electrode active material includes nickel oxide (NiO).

9. The solid oxide composite according to claim 1, wherein, The oxide-based electrode active material includes an air electrode active material, and the air electrode active material includes 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 a combination thereof.

10. A method for manufacturing a solid oxide composite, the method comprising: Filling a first pore of a silica template with a solid oxide electrolyte; Removing the silica template with an alkaline solution to prepare a solid oxide electrolyte including second pores; and Filling the second pores of the solid oxide electrolyte with an oxide-based electrode active material.

11. The method according to claim 10, wherein, Filling the first pore of the silica template with the solid oxide electrolyte includes a first process of filling the first pore of the silica template with a part of the solid oxide electrolyte precursor and a second process of filling the first pore of the silica template with the remaining solid oxide electrolyte precursor, wherein the weight ratio of the solid oxide electrolyte precursor filled in the first pore in the first process to the solid oxide electrolyte precursor added to the first pore in the second process is from 1.5:1 to 3:

1.

12. The method according to claim 10, wherein, Filling the second pores of the solid oxide electrolyte with the oxide-based electrode active material is repeated 1 to 5 times.

13. The method according to claim 10, wherein, The silica template includes MCM-41, MCM-48, MCM-50, SBA-11, SBA-12, SBA-15, SBA-16, KIT-5, KIT-6, FDU-2, or COK-12.

14. The method according to claim 10, wherein, The first pores of the silica template have a helical structure.

15. The method according to claim 10, wherein, The second pores of the solid oxide electrolyte have a reverse pore structure of the silica template.

16. The method according to claim 10, wherein, The pores of the solid oxide electrolyte have a reverse pore structure of the silica template.

17. A solid oxide fuel cell, comprising: An air electrode; A solid oxide electrolyte layer; and A fuel electrode, wherein the fuel electrode or the air electrode includes the solid oxide composite according to claim 1.

18. A solid oxide electrolyzer cell, comprising: An air electrode; A solid oxide electrolyte layer; and A fuel electrode, Wherein, the fuel electrode or the air electrode comprises the solid oxide composite according to Claim 1.

19. A solid oxide composite, comprising: An oxide-based electrode active material, comprising pores; and A solid oxide electrolyte, within the pores.

20. The solid oxide composite according to claim 19, wherein, The average size of the pores is from 2 nm to 50 nm.

21. The solid oxide composite according to claim 19, wherein, The weight ratio of the solid oxide electrolyte to the oxide-based electrode active material is from 40:60 to 60:

40.

22. The solid oxide composite according to claim 19, wherein, The solid oxide electrolyte comprises YSZ (yttria-stabilized zirconia), ScSZ (scandia-stabilized zirconia), GDC (gadolinium-doped ceria), SDC (samarium-doped ceria), LSGM (lanthanum strontium gallium magnesium oxide), or a combination thereof.

23. The solid oxide composite according to claim 19, wherein, The oxide-based electrode active material comprises a fuel electrode active material, and the fuel electrode active material comprises nickel oxide (NiO).

24. The solid oxide composite according to claim 19, wherein, The oxide-based electrode active material comprises an air electrode active material, and The air electrode active material comprises lanthanum strontium manganite (LSM), lanthanum strontium ferrite (LSF), lanthanum strontium cobaltite (LSC), lanthanum strontium cobalt ferrite (LSCF), samarium strontium cobaltite (SSC), barium strontium cobalt ferrite (BSCF), bismuth ruthenate, or a combination thereof.

25. A solid oxide composite, comprising: A solid oxide electrolyte and an oxide-based electrode active material, Wherein, one of the solid oxide electrolyte and the oxide-based electrode active material comprises a plurality of pores, and the other of the solid oxide electrolyte and the oxide-based electrode active material is disposed within the plurality of pores such that the solid oxide electrolyte and the oxide-based electrode active material are interspersed.

26. The solid oxide composite according to claim 25, wherein, The weight ratio of the solid oxide electrolyte to the oxide-based electrode active material is from 40:60 to 60:

40.

27. The solid oxide composite according to claim 25, wherein, The solid oxide electrolyte comprises YSZ (yttria-stabilized zirconia), ScSZ (scandia-stabilized zirconia), GDC (gadolinium-doped ceria), SDC (samarium-doped ceria), LSGM (lanthanum strontium gallium magnesium oxide), or a combination thereof.

28. The solid oxide composite according to claim 25, wherein, The oxide-based electrode active material comprises a fuel electrode active material, and the fuel electrode active material comprises nickel oxide (NiO).

29. The solid oxide composite according to claim 25, wherein, The oxide-based electrode active material comprises an air electrode active material, and The air electrode active material comprises lanthanum strontium manganite (LSM), lanthanum strontium ferrite (LSF), lanthanum strontium cobaltite (LSC), lanthanum strontium cobalt ferrite (LSCF), samarium strontium cobaltite (SSC), barium strontium cobalt ferrite (BSCF), bismuth ruthenate, or a combination thereof.

Images