Cathode material including bismuth-doped manganite-based perovskite and solid oxide fuel cell including same

Abstract

The present invention relates to an air electrode material comprising a manganite-based perovskite doped with bismuth, which has excellent electrochemical properties and long-term stability, and a solid oxide fuel cell comprising the same. The air electrode material according to the example comprises a bismuth-doped manganite-based perovskite represented by the following chemical formula 1, wherein bismuth is doped into praseodymium strontium manganite (wherein in the following chemical formula 1, X is 0 < X ​​< 0.5 and δ is 0 < δ < 2). [Chemical Formula 1] Pr0.8-xBixSr0.2MnO3-δ

Description

Technology Field

[0001] The present invention relates to an air electrode material comprising a manganite-based perovskite doped with bismuth, which has excellent electrochemical properties and long-term stability, and a solid oxide fuel cell comprising the same. Background Technology

[0002] In general, solid oxide batteries (SOCs) are being extensively studied as energy systems capable of replacing intermittent renewable energy sources because they have high efficiency and can operate reversibly in fuel cell (FC) mode for power generation and electrolysis cell (EC) mode for hydrogen production as clean electrochemical energy converters.

[0003] Conventional solid oxide batteries operate at high temperatures of 750°C or higher, which limits the selection of materials and leads to high system costs due to rapid performance degradation caused by thermomechanical and chemical instability. Consequently, various studies have recently been conducted on methods to lower the operating temperature of solid oxide batteries.

[0004] When the operating temperature of the aforementioned solid oxide cell is lowered, reactions at the air electrode, including the oxygen reduction reaction (ORR) in fuel cell mode and the oxygen evolution reaction (OER) in electrolysis cell mode, slow down drastically, which predominantly affects the performance of the solid oxide cell. Accordingly, research is focusing on the development of highly active air electrodes containing perovskite materials, and cobalt-containing perovskite oxides such as praseodymium barium strontium cobalt iron oxide (PBSCF), barium strontium cobalt iron oxide (BSCF), and lanthanum strontium cobalt iron oxide (LSCF), which exhibit excellent mixed ion, electron conductivity (MIEC), and catalytic activity, are primarily used as state-of-the-art air electrode materials. These cobalt-containing perovskite oxides possess enhanced oxygen vacancy formation and oxygen diffusion characteristics compared to other perovskites.

[0005] However, despite their high performance, the aforementioned cobalt-containing perovskite oxide has disadvantages when directly applied as an air electrode, such as chemical instability including surface segregation and decomposition, and thermomechanical incompatibility with yttria-stabilized zirconia (YSZ), the most popular electrolyte material, due to its high coefficient of thermal expansion.

[0006] Accordingly, additional coating is required on the electrode surface or the buffer layer between the electrode and the electrolyte, and alternative doping strategies are being proposed to replace cobalt to suppress chemical reactions or thermal expansion.

[0007] In this regard, the development of alternative materials has been emphasized, and it is desirable to mitigate the harmful effects of cobalt-containing materials. Among cobalt-free perovskites, Ln 1-x Sr x MnO 3-δManganese-based perovskite materials such as (Ln = La, Pr, Nd, Sm, Gd, Yb or Y) have high electronic conductivity and a coefficient of thermal expansion similar to YSZ, but due to low ionic conductivity resulting from poor MIEC properties, the catalytic active sites are mainly limited to the triple phase boundary (TPB) where the electrode-electrolyte-air meet, and the reported catalytic activity is relatively low.

[0008] Although doping strategies are utilized in various studies as a method to enhance oxygen ion transport characteristics, no significant improvement surpassing the performance of cobalt-containing perovskites has been reported, even when elements containing transition metals are considered as dopants. Consequently, the development of manganese-based perovskite materials is facing a bottleneck, and since the focus has been on developing composite electrodes to extend the length of the three-phase boundary (TPB) rather than on the material properties themselves, research on different systems of methods to complement this is necessary. Prior art literature

[0009] Document 1: Bismuth doped La0.75Sr0.25Cr0.5Mn0.5O3δ perovskite as a novel redox-stable efficient anode for solid oxide fuel cells (Shaowei Zhang, Yanhong Wan, Zheqiang Xu, Shuangshuang Xue, Lijie Zhang, Binze Zhangga and Changrong Xia, Journal of Materials Chemistry A, Issue 23, 2020) Document 2: Effect of bismuth doping on the physical properties of La-Li-Mn-O manganite (Kalyana Lakshmi Yanapu, Springer, February 2016) The problem to be solved

[0010] Accordingly, one embodiment of the present invention, which aims to solve the problems of the aforementioned prior art, has the objective of providing a technical description of an air electrode material that exhibits high electrochemical properties and excellent long-term stability by doping bismuth (Bi) into a praseodymium strontium manganite-based perovskite, and a solid oxide fuel cell containing the same.

[0011] The technical problems that the present invention aims to solve are not limited to those mentioned above, and other unmentioned technical problems will be clearly understood by those skilled in the art to which the present invention belongs from the description below. means of solving the problem

[0012] One embodiment of the present invention for achieving the above-described objective provides an air electrode material comprising a bismuth-doped manganite-based perovskite represented by the following chemical formula 1, wherein bismuth is doped into praseodymium strontium manganite (wherein X is 0 < X ​​< 0.5 and δ is 0 < δ < 2).

[0013] [Chemical Formula 1]

[0014] Pr 0.8-x Bi x Sr 0.2 MnO 3-δ

[0015] According to one embodiment, in the above chemical formula 1, X may be 0.2 < X < 0.4.

[0016] According to one embodiment, the air electrode material can be used as a material for manufacturing an air electrode of a solid oxide fuel cell, particularly a bidirectional solid oxide fuel cell.

[0017] Meanwhile, a method for manufacturing an air electrode material is provided, comprising the steps of: preparing a precursor mixture by mixing a praseodymium precursor, a bismuth precursor, a strontium precursor, a manganese precursor, and glycine with distilled water; drying the precursor mixture to prepare a dried precursor, and heating and burning the dried precursor to prepare a combusted product; grinding the combusted product to prepare a combusted product powder; and calcining the combusted product powder to prepare an air electrode material comprising a bismuth-doped manganite-based perovskite represented by the following chemical formula 1 (wherein in the following chemical formula 1, X is 0 < X ​​< 0.5 and δ is 0 < δ < 2).

[0018] [Chemical Formula 1]

[0019] Pr 0.8-x Bi x Sr 0.2 MnO 3-δ

[0020] In addition, a bidirectional solid oxide fuel cell is provided, comprising: an air electrode manufactured from the air electrode material described in claim 1; an electrolyte layer located on the air electrode; and a fuel electrode located on the electrolyte layer.

[0021] According to one embodiment, the solid oxide fuel cell has an air electrode of 350 mA / Cm at 700 ℃. 2 If a current density of is applied, 6.3 × 10⁻⁶ for 480 hours -7 It can exhibit a degradation rate of V / h and 0.58 to 2.24 W / Cm at 600 to 750 ℃. 2 It can represent the power density of. Effects of the invention

[0022] The air electrode material according to the example is a praseodymium strontium manganite-based perovskite structure doped with bismuth (Bi) to exhibit high electrochemical properties and excellent long-term stability, and accordingly, can be utilized for manufacturing air electrodes of solid oxide fuel cells.

[0023] The effects of the present invention are not limited to the effects described above, and should be understood to include all effects that can be inferred from the configuration of the invention described in the detailed description or claims of the present invention. Brief explanation of the drawing

[0024] Figure 1 is a process diagram showing a method for manufacturing an air electrode according to an embodiment. Figure 2 is the result of X-ray diffraction pattern analysis for powder samples (PSM, PBSM1, PBSM3, PBSM5) prepared by the method according to the example. Figure 3 shows the results of evaluating the electrical characteristics of a half-cell applied to a YSZ electrolyte using an air electrode prepared using powder samples (PSM, PBSM1, PBSM3) according to the example. Figure 4 shows the results of analyzing the microstructure of a half-cell in which an air electrode prepared from a powder sample (PBSM3) according to an example is applied to a YSZ electrolyte. Figure 5 shows the results of evaluating the performance of a unit cell including an air electrode made of a powder sample (PBSM3) according to an example in fuel cell and electrolytic cell modes at different temperatures. Figure 6 is the result of evaluating the long-term stability of a unit cell including an air electrode prepared with a powder sample (PBSM3) according to an example. Specific details for implementing the invention

[0025] The present invention will be described below with reference to the attached drawings. However, the present invention may be implemented in various different forms and is therefore not limited to the embodiments described herein. Furthermore, in order to clearly explain the present invention in the drawings, parts unrelated to the explanation have been omitted, and similar parts throughout the specification have been given similar reference numerals.

[0026] Throughout the specification, when it is stated that a part is "connected (connected, in contact, combined)" with another part, this includes not only cases where they are "directly connected," but also cases where they are "indirectly connected" with other members interposed between them. Furthermore, when it is stated that a part "includes" a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but rather allows for the inclusion of additional components.

[0027] The terms used herein are merely for describing specific embodiments and are not intended to limit the invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this specification, terms such as “comprising” or “having” are intended to indicate the presence of the features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, and should be understood as not precluding the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0028] Embodiments of the present invention will be described in detail below with reference to the attached drawings.

[0029] The air electrode material comprising a bismuth-doped manganite-based perovskite according to the example has a structure represented by the following chemical formula 1, in which bismuth (Bi) is doped into praseodymium strontium manganite (PrSrMnO).

[0030] [Chemical Formula 1]

[0031] Pr 0.8-x Bi x Sr 0.2 MnO 3-δ

[0032] Accordingly, the air electrode material described above has a structure in which electrochemical properties and long-term stability are improved by doping with bismuth.

[0033] In order to exhibit the above characteristics, in the above chemical formula 1, X can have a range of 0 < X ​​< 0.5 and δ can have a range of 0 < δ < 2.

[0034] In the above Chemical Formula 1, if X is 0, bismuth is not doped, so it is difficult to expect an improvement in physical properties, and if X exceeds 0.5, the amount of bismuth doping is high, so Pr 1.1 Bi 0.9 Mn4O 10 There is a concern that secondary phases such as the above may be formed, thereby degrading physical properties. That is, it is preferable that the bismuth-doped manganite-based perovskite has a bismuth doping amount greater than 0 and less than 0.5 mol.

[0035] In particular, in the above chemical formula 1, X may be 0.2 < X < 0.4.

[0036] The bismuth (Bi)-doped manganite-based perovskite described above can be used as an air electrode material, and in particular, can be used as an air electrode material for bidirectional solid oxide fuel cells.

[0037] The doping of the above bismuth (Bi) can be carried out by processes that artificially inject a dopant, such as diffusion and ion implantation, but is not limited thereto.

[0038] Meanwhile, FIG. 1 is a process diagram showing a method for manufacturing an air electrode material according to an embodiment.

[0039] Referring to FIG. 1, a method for manufacturing an air electrode material according to an embodiment can manufacture an air electrode material comprising a bismuth-doped manganite-based perovskite represented by the following chemical formula 1 through a glycine nitrate process comprising the steps of: manufacturing a precursor mixture (S100); manufacturing a combustion product (S200); and manufacturing an air electrode material (S300).

[0040] [Chemical Formula 1]

[0041] Pr 0.8-x Bi x Sr 0.2 MnO 3-δ

[0042] Looking in detail at the method for manufacturing the above air electrode material, first, in the step of manufacturing a precursor mixture (S100), a precursor mixture can be manufactured by mixing a praseodymium precursor, a bismuth precursor, a strontium precursor, a manganese precursor, and glycine with distilled water.

[0043] The above praseodymium precursor, bismuth precursor, strontium precursor, and manganese precursor can each be any of the various conventional forms of precursors used for the preparation of perovskite compounds.

[0044] Specifically, representative examples of the above praseodymium precursor include praseodymium nitrate (Pr(NO3)36H2O), the above bismuth precursor includes bismuth nitrate (Bi(NO3)35H2O), the above strontium precursor includes strontium nitrate (Sr(NO3)2), and the above manganese precursor includes manganese nitrate (Mn(NO3)24H2O).

[0045] In this step, a precursor mixture can be prepared by mixing a praseodymium precursor, a bismuth precursor, a strontium precursor, and a manganese precursor in distilled water in stoichiometric ratios, then adding glycine and mixing uniformly. The precursor mixture can be mixed by heating it to a temperature of 50 to 90°C so that the precursors and glycine are uniformly mixed. Subsequently, moisture can be removed from the precursor mixture, and the dried precursor can be burned in the step to be described later to produce a combustible product.

[0046] Next, the step of manufacturing a combustion product (S200) may involve removing moisture from the precursor mixture as described above and then burning the precursor mixture at a temperature of 200 to 500 °C. In this step, a combustion product containing manganite-based perovskite may be formed through a glycine nitrate process that induces an exothermic reaction between glycine and nitrate.

[0047] Next, the step of manufacturing an air electrode material (S300) may be to obtain the combustion product and calcinate the obtained combustion product to produce a composite powder in which bismuth is doped into a manganite-based perovskite. In this step, a calcination process may be performed at a temperature of 800 to 1,200 ℃ for 0.5 to 24 hours to produce a composite powder containing bismuth-doped manganite-based perovskite.

[0048] Subsequently, the bismuth-doped manganite-based perovskite as described above can be ground to produce a powder form. Specifically, the grinding can utilize conventional methods such as ball milling, and the composite powder can be produced in the form of nanometer-sized particles through a process of mixing the composite powder with ethanol and then ball milling.

[0049] Meanwhile, the solid oxide fuel cell according to the embodiment may have a structure comprising an air electrode manufactured from the air electrode material as described above, an electrolyte layer located on the air electrode, and a fuel electrode located on the electrolyte layer.

[0050] A solid oxide fuel cell having the above-described structure includes an air electrode manufactured using bismuth-doped manganite-based perovskite, and exhibits improved electrochemical properties and long-term stability.

[0051] Specifically, the solid oxide fuel cell has an air electrode of 250 mA / Cm at 700 ℃. 2 If applied, 6.3 × 10 for 480 hours -7It exhibits excellent long-term stability characteristics by being able to show a degradation rate of V / h.

[0052] In addition, the solid oxide fuel cell has 0.58 to 2.24 W / Cm at 600 to 750 ℃ ​​in fuel cell mode. 2 It can exhibit a power density of 0.6 to 2.7 A / Cm in electrolytic cell mode. 2 It can exhibit excellent electrical characteristics by displaying the current density.

[0053] In particular, the solid oxide fuel cell may be a bidirectional solid oxide fuel cell, and the bidirectional solid oxide fuel cell may form an air electrode that exhibits high performance in fuel cell mode and electrolytic cell mode by doping less than 0.5 mol of bismuth.

[0054] The air electrode material according to the above-described embodiment is doped with bismuth (Bi) in a praseodymium strontium manganite-based perovskite structure and exhibits high electrochemical properties while also having excellent long-term stability, and accordingly, can be utilized for manufacturing air electrodes of solid oxide fuel cells.

[0055] The present invention will be explained in more detail below with reference to examples.

[0056] The presented embodiments are merely specific examples of the invention and are not intended to limit the technical scope of the invention.

[0057] <Example>

[0058] A praseodymium strontium manganite-based compound (Pr) having the composition shown in Table 1 below, by a high-temperature continuous reaction method using a combustion material containing glycine 0.8-x Bi x Sr 0.2 MnO 3-δA nanopowder containing ) was synthesized. The nanopowder was synthesized through the glycine nitrate process, which is a type of combustion synthesis process.

[0059] PSM Pr 0.8 Sr 0.2 MnO 3-δ PBSM1 Pr 0.7 Bi 0.1 Sr 0.2 MnO 3-δ PBSM3 Pr 0.5 Bi 0.3 Sr 0.2 MnO 3-δ PBSM5 Pr 0.3 Bi 0.5 Sr 0.2 MnO 3-δ

[0060] Specifically, bismuth-doped praseodymium strontium manganite compounds (Pr 0.8-x Bi x Sr 0.2 MnO 3-δ ) and praseodymium strontium manganite-based compounds (Pr 0.8 Sr 0.2 MnO 3-δ The ) was prepared by the following method. First, precursor materials containing praseodymium nitrate (Pr(NO3)36H2O, Sigma Aldrich, 99.9%), bismuth nitrate (Bi(NO3)35H2O, Alfa Aesar, 98%), strontium nitrate (Sr(NO3)2, Alfa Aesar, 99.0%), and manganese nitrate (Mn(NO3)24H2O, Sigma Aldrich, 97.0%) were prepared. The prepared precursor materials were mixed with distilled water in stoichiometric ratios and stirred to prepare a mixture. Glycine was added to the prepared mixture and stirred at 80 °C to prepare a homogeneous mixed solution. Subsequently, the solution was dried at 120 °C to evaporate all moisture, and then heated to 300 °C to induce a combustion reaction. The ash remaining after the combustion reaction was ground using a mortar and pestle to produce powder. The prepared powder was calcined at 1000 °C for 2 hours. Zirconia balls and ethanol were added to the obtained calcined material, and a ball-milling process was carried out for 24 hours. After mixing and grinding, black final powder samples (PSM, PBSM1, PBSM3, PBSM5) were obtained, respectively.

[0061] <Experimental Example> (1) Crystal structure analysis

[0062] Powder XRD measurements were performed using an X-ray diffraction analyzer (RIGAKU, SmartLab) with Cu Kα radiation (λ = 1.5418 Å) in the 2θ range of 20 to 80°. The crystal structure of the powder was refined using HighScore software.

[0063] Figure 2 is the result of X-ray diffraction pattern analysis for powder samples (PSM, PBSM1, PBSM3, PBSM5) prepared by the method according to the example.

[0064] As shown in Fig. 2, it was confirmed that PBSM1, PBSM3, and PBSM5, which are Bi-doped PSMs, form an orthorhombic perovskite phase. In addition, it was observed that the main peak around 32 to 33° shifted to a lower angle as the doping amount of bismuth increased. These results are due to praseodymium (Pr 3+ Compared to the radius of the ion (1.17 Å), bismuth (Bi 3+ This is due to the larger radius of the ion (1.13 Å).

[0065] In addition, in the case of PBSM5 where the bismuth doping amount is 0.5 mol or more, the secondary phase Pr 1.1 Bi 0.9 Mn4O 10 It was confirmed that this is formed.

[0066] (2) Fabrication of half cells and unit cells

[0067] To produce half-sheets, YSZ (Yttria-stabilized Zirconia, TOSHO) powder was placed into a mold and uniaxial pressing was applied at a pressure of 50 MPa, followed by sintering at 1400 °C for 10 hours to produce YSZ pellets.

[0068] Tape casting and screen printing techniques were used to sequentially stack the fuel electrode support layer, fuel electrode functional layer, and electrolyte layer constituting the unit cell.

[0069] (3) Evaluation of electrochemical properties

[0070] The electrochemical characteristics of half cells and unit cells were evaluated using a potentiostat (Bio-Logic, VMP-300). For half cells, the evaluation was performed in ambient air, while for unit cells, hydrogen (3% wet) and air were injected into the fuel electrode and air electrode, respectively.

[0071] In addition, the ionic conductivity of the prepared EYZB pellet was measured using a potentiostat in a temperature range of 550 to 750 °C. In addition, the long-term durability evaluation of the material was performed at a temperature of 600 °C.

[0072] In addition, XRD measurements of the pellets used for long-term durability evaluation were performed using an X-ray diffraction analyzer (RIGAKU, SmartLab) with Cu Kα radiation (λ = 1.5418 Å) in the 2θ range of 20 to 80°. The crystal structure of the pellets was refined using HighScore software.

[0073] Figure 3 shows the results of evaluating the electrical characteristics of a half-cell applied to a YSZ electrolyte using an air electrode prepared using powder samples (PSM, PBSM1, PBSM3) according to the example.

[0074] Referring to Figure 3, in the case of half-cells in which PSM, PBSM1, and PBSM3 air electrodes were applied to the YSZ electrolyte, it was confirmed that the electrode resistance decreased as the doping amount of bismuth increased, thereby confirming that the electrical characteristics were improved.

[0075] (4) Microstructure analysis

[0076] Microstructure analysis of the unit cell was performed using a scanning electron microscope (SEM, Hitachi SU8230).

[0077] Figure 4 shows the results of analyzing the microstructure of a half-cell in which an air electrode prepared from a powder sample (PBSM3) according to an example is applied to a YSZ electrolyte.

[0078] Referring to Figure 4, it can be seen that the cell is composed of an air electrode, an electrolyte, and a fuel electrode as a whole, and the electrolyte has a dense structure with a thickness of approximately 5 μm, and it can be seen that the air electrode and the electrolyte are bonded together without any delamination.

[0079] (5) Evaluation of electrochemical characteristics of the unit cell

[0080] Figure 5 shows the results of evaluating the performance of a unit cell including an air electrode made of a powder sample (PBSM3) according to an example in fuel cell and electrolytic cell modes at different temperatures.

[0081] Referring to FIG. 5, in fuel cell mode, the values ​​are 2.24, 1.90, 1.26, and 0.58 W / Cm at 750 ℃, 700 ℃, 650 ℃, and 600 ℃, respectively. 2 It was confirmed to be 2.7, 1.9, 0.9, and 0.6 A / Cm in electrolytic cell mode, respectively. 2 It was confirmed to be.

[0082] Figure 6 is the result of evaluating the long-term stability of a unit cell including an air electrode prepared with a powder sample (PBSM3) according to an example.

[0083] As shown in Fig. 6, 250 mA / Cm at 700 ℃ 2 If applied, 6.3 × 10 for 480 hours -7 It was confirmed to exhibit a degradation rate of V / h.

[0084] Based on the above results, it was determined that this material can be utilized as an oxygen electrode for reversible solid oxide batteries with excellent performance and stability without a buffer layer on a popular YSZ electrolyte.

[0085] In addition, crystallographic analysis confirmed that impurities are formed when bismuth is doped in amounts of 0.5 mol or more in the manganite-based perovskite structure, and that when doped in amounts of less than 0.5 mol, the perovskite structure has an orthorhombic structure free of impurities.

[0086] In addition, the electrochemical characteristics of half-cells equipped with the developed air electrode were evaluated, and it was confirmed that PBSM3 exhibited the lowest electrode resistance. When the electrode was measured in fuel cell and electrolytic cell modes, the results were 1.90 W / Cm at 700 °C, respectively. 2 and 1.91 A / Cm 2 It was confirmed to possess high performance. In addition, as a result of performing a long-term stability evaluation at 700°C in fuel cell mode, 6.3 × 10⁻⁶ was achieved for over 480 hours. -7 It was confirmed to exhibit a degradation rate of V / h.

[0087] Therefore, it was confirmed that high performance and long-term stability are achieved when operating in fuel cell and electrolytic cell modes on the most popular YSZ electrolyte without the stacking of a buffer layer, and in particular, it was confirmed that the PBSM3 material is a very promising material for reversible solid oxide cells.

[0088] Although the technical concept of the present invention described above has been specifically described in preferred embodiments, it should be noted that the aforementioned embodiments are for illustrative purposes only and are not intended to be limiting. Furthermore, those skilled in the art will understand that various embodiments are possible within the scope of the technical concept of the present invention. Accordingly, the true scope of technical protection of the present invention should be determined by the technical concept of the appended claims.

Claims

Claim 1 An air electrode material comprising a bismuth-doped manganite-based perovskite represented by the following Chemical Formula 1, wherein bismuth is doped into praseodymium strontium manganite (provided that in Chemical Formula 1 below, X is 0.2 < X < 0.4 and δ is 0 < δ < 2). [Chemical Formula 1]Pr 0.8-x Bi x Sr 0.2 MnO 3-δ Claim 2 delete Claim 3 An air electrode material according to claim 1, characterized in that the air electrode material is for a bidirectional solid oxide fuel cell. Claim 4 A method for manufacturing an air electrode material comprising: a step of preparing a precursor mixture by mixing a praseodymium precursor, a bismuth precursor, a strontium precursor, a manganese precursor, and glycine with distilled water; a step of preparing a dried precursor by drying the precursor mixture, heating the dried precursor, and then burning it to prepare a combusted product; and a step of calcining the combusted product to manufacture an air electrode material comprising a bismuth-doped manganite-based perovskite represented by the following Chemical Formula 1 (wherein in the following Chemical Formula 1, X is 0 < X ​​< 0.5 and δ is 0 < δ < 2). [Chemical Formula 1]Pr 0.8-x Bi x Sr 0.2 MnO 3-δ Claim 5 A method for preparing a bismuth-doped manganite-based perovskite according to claim 4, characterized in that X in Chemical Formula 1 is 0.2 < X < 0.

4. Claim 6 A bidirectional solid oxide fuel cell comprising: an air electrode manufactured from the air electrode material described in claim 1; an electrolyte layer located on the air electrode; and a fuel electrode located on the electrolyte layer. Claim 7 In claim 6, the air electrode is 350 mA / Cm at 700 ℃ 2 If applied, 6.3 × 10 for 480 hours -7 A bidirectional solid oxide fuel cell characterized by exhibiting a degradation rate of V / h. Claim 8 In claim 6, 0.58 to 2.24 W / Cm at 600 to 750 ℃ 2 A bidirectional solid oxide fuel cell characterized by exhibiting a power density.

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