Electrode materials, membrane electrode assemblies, electrochemical cells and fuel cell systems

Abstract

This electrode material of the present disclosure contains a compound represented by chemical formula ＢａＺｒ1-x-yＭxＣｏyＯ3-δ. Here, M represents In or Yb, and ０＜ｘ＜１, ０＜ｙ＜１, ０＜（ｘ＋ｙ）＜１ and ０＜δ＜１ are satisfied. A membrane-electrode assembly 10 of the present disclosure comprises: a first electrode 12 containing the electrode material; and an electrolyte membrane 11 disposed on a first main surface 12a of the first electrode 12.

Description

Technical Field

[0001] The present disclosure relates to an electrode material, a membrane electrode assembly, an electrochemical cell, and a fuel cell system.

Background Art

[0002] As one of the electrochemical cells using an electrolyte material made of a solid oxide, for example, a solid oxide fuel cell (hereinafter referred to as "SOFC") is known. As the electrolyte material of SOFC, an oxide ion conductor typified by stabilized zirconia is generally widely used. The lower the temperature, the lower the ion conductivity of the oxide ion conductor. Therefore, an SOFC using stabilized zirconia as an electrolyte material requires an operating temperature of, for example, 700°C or higher.

[0003] On the other hand, an SOFC using an electrolyte material having proton conductivity can operate, for example, at about 500°C to 600°C. This is because the activation energy in proton conduction is smaller than that in oxide ion conduction, and the ion conductivity is less likely to decrease even at low temperatures. Therefore, SOFCs using an electrolyte material having proton conductivity have attracted attention from the viewpoints of chemical stability of members and cost reduction.

[0004] As a typical electrolyte material having proton conductivity, the chemical formula BaCe 1-x M x O 3-α 、BaZr 1-x-y Ce x M y O 3-α Or BaZr 1-x M x O 3-α The perovskite-type composite oxide represented by is known. In these chemical formulas, M is a trivalent substitution element. The value of α is the amount of oxygen deficiency. The values of x and y satisfy 0 < x < 1, 0 < y < 1, and 0 < (x + y) < 1.

[0005] For example, as described in Patent Document 1 and Patent Document 2, conventionally, perovskite-type composite oxides having proton conductivity have been proposed as electrolyte materials constituting the electrolyte membrane of SOFCs.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0007] Generally, in SOFCs using an electrolyte material having proton conductivity, the same electrode materials as those used in SOFCs using an electrolyte material having oxide ion conductivity are used. Therefore, for example, there is a demand for the development of an electrode material that can be suitably used in an SOFC using an electrolyte material having proton conductivity and that can exhibit excellent performance as an electrode.

[0008] An object of the present disclosure is to provide an electrode material that exhibits excellent performance as an electrode.

Means for Solving the Problems

[0009] The electrode material according to the present disclosure contains a compound represented by the chemical formula BaZr 1-x-y M x Co y O 3-δ where M is In or Yb, and 0 < x < 1, 0 < y < 1, 0 < (x + y) < 1, and 0 < δ < 1 are satisfied.

Effects of the Invention

[0010] The present disclosure provides an electrode material that exhibits excellent performance as an electrode.

Brief Description of the Drawings

[0011] [Figure 1A] FIG. 1A shows a cross-sectional view of a membrane electrode assembly according to embodiment 3. [Figure 1B] FIG. 1B shows a cross-sectional view of an electrochemical cell according to embodiment 4. [Diagram 2] FIG. 2 shows a fuel cell system according to a fifth embodiment. [Diagram 3] FIG. 3 is a graph showing the X-ray diffraction profile of the electrode material according to Example 1. [Figure 4] FIG. 4 is a graph showing the X-ray diffraction profile of the electrode material according to Example 2. [Diagram 5] FIG. 5 is a graph showing the X-ray diffraction profiles of the electrode materials according to Examples 3 to 8. [Figure 6] FIG. 6 is a graph showing the X-ray diffraction profiles of the electrode materials according to Examples 9 to 14. [Figure 7] FIG. 7 is a graph showing the X-ray diffraction profiles of the electrode materials according to Examples 15 to 21. [Figure 8] FIG. 8 shows a Nyquist plot of the evaluation cell in which the electrode material according to Example 1 was used. [Figure 9] FIG. 9 shows a Nyquist plot of the evaluation cell in which the electrode material according to Comparative Example 1 was used. [Figure 10] FIG. 10 shows a Nyquist plot of the evaluation cell in which the electrode material according to Comparative Example 2 was used. [Figure 11] FIG. 11 is a graph showing the X-ray diffraction profile of the electrode material according to Example 22. [Figure 12] FIG. 12 is a graph showing the X-ray diffraction profile of the electrode material according to Example 23. [Figure 13] FIG. 13 is a graph showing the X-ray diffraction profiles of the electrode materials according to Examples 24 to 29. [Figure 14] FIG. 14 is a graph showing the X-ray diffraction profiles of the electrode materials according to Examples 30 to 35. [Figure 15]FIG. 15 is a graph showing the X-ray diffraction profiles of the electrode materials according to Examples 36 to 42. [Figure 16] FIG. 16 is a graph showing the X-ray diffraction profiles of the electrode materials according to Examples 43 to 48. [Figure 17] FIG. 17 shows the Nyquist plot of the evaluation cell using the electrode material according to Example 22. [Figure 18] FIG. 18 shows the Nyquist plot of the evaluation cell using the electrode material according to Comparative Example 3.

Mode for Carrying Out the Invention

[0012] (Process for Obtaining One Embodiment of the Present Disclosure) Patent Document 1 lists a metal oxide having a perovskite structure containing at least one of transition metals nickel, cobalt, chromium, manganese, and iron in a molar ratio of 0.01 or more and 0.2 or less as a proton conductive material excellent in low-temperature sinterability. In Patent Document 1, it is described that transition metals such as nickel are elements effective for improving low-temperature sinterability, chemical stability in the high-temperature region, denseness, and mechanical strength. Although not examined in Patent Document 1, there are some in which catalytic activity has been confirmed for these transition metal elements alone or compounds containing these transition metal elements. For example, nickel is used as a fuel electrode in SOFC.

[0013] Patent Document 2 provides a perovskite-type structure oxide represented by the chemical formula BaZr 1-x M x O 3-p which has a high proton conductivity and high physical and chemical stability. Here, the chemical formula BaZr 1-x M x O 3-p satisfies 0 < x < 1 and 0 < p < 1.5. The chemical formula BaZr 1-x M x O 3-pIn this case, M is a trivalent substitution element. The substitution element M is at least one element selected from La, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Y, Sc, Mn, Fe, Co, Ni, Al, Ga, and In. Although not studied in Patent Document 2, among the elements exemplified as the substitution element M, some simple transition metal elements or compounds containing these transition metal elements have been confirmed to have catalytic activity. For example, nickel is used as a fuel electrode in SOFCs.

[0014] Here, as a result of intensive studies on the proton-conductive materials disclosed in Patent Document 1 and Patent Document 2, the present inventors have obtained the following findings. That is, the present inventors have found that by adding cobalt, which is a transition element, to a material having proton conductivity, catalytic activity can be expressed in the material and it can be provided as an electrode material, leading to the present disclosure described below.

[0015] (Embodiment 1) The electrode material according to Embodiment 1 has a compound represented by the chemical formula BaZr 1-x-y M x Co y O 3-δ where M is In. That is, the electrode material according to Embodiment 1 contains a compound represented by the chemical formula BaZr 1-x-y In x Co y O 3-δ as shown in Examples 1 to 21 described below. Here, this chemical formula satisfies 0 < x < 1, 0 < y < 1, 0 < (x + y) < 1, and 0 < δ < 1. The electrode material according to Embodiment 1 can have a low reaction resistance, for example, at a temperature of 600°C. Therefore, the electrode material according to Embodiment 1 can function as an electrode material that can be used, for example, for the electrodes of SOFCs. Note that the electrode material according to Embodiment 1 may satisfy 0 < δ < 0.5.

[0016] The electrode material according to Embodiment 1 has, for example, 6 Ωcm at 600°C 2The electrode material according to embodiment 1 may have the following reaction resistance: When the electrode material according to embodiment 1 has such a low reaction resistance, the electrode material according to embodiment 1 can exhibit excellent performance as an electrode.

[0017] The above formula is BaZr 1-x-y In x Co y O 3-δ The compound represented by the formula (I) has proton conductivity. Therefore, when the electrode material according to the first embodiment is used in the air electrode of an SOFC in which an electrolyte material having proton conductivity is used in the electrolyte membrane, not only the air electrode, the electrolyte membrane, and the oxygen contact surface (i.e., the three-phase interface of the air electrode, the electrolyte membrane, and oxygen) but also the air electrode and the oxygen contact surface (i.e., the two-phase interface of the air electrode and oxygen) can be used as a reaction field. Therefore, when the electrode material according to the first embodiment is used in the electrode of an SOFC in which an electrolyte material having proton conductivity is used in the electrolyte membrane, it can exhibit excellent performance as an electrode.

[0018] The electrode material according to the first embodiment is, for example, represented by the above chemical formula BaZr 1-x-y In x Co y O 3-δ The compound represented by the chemical formula BaZr may be contained in an amount of 30% or more, or 50% or more by mole. 1-x-y In x Co y O 3-δ By containing the compound represented by the formula (1), the electrode material according to the embodiment 1 can exhibit more excellent performance as an electrode.

[0019] The above formula is BaZr 1-x-y In x Co y O 3-δ The compound represented by the formula: The following formulas (1) to (3) may be satisfied. Formula (1): 0.125≦y≦0.5 Formula (2): y≦3x-0.25 Formula (3): y≦-3x+2

[0020] As shown in Examples 1, 3, 8 to 11, and 13 to 19 described later, an electrode material containing a compound satisfying the above formulas (1) to (3) has a resistance of 12.3 Ωcm 2 (i.e., a reaction resistance value lower than the reaction resistance value of Comparative Example 1 described later). Therefore, it is considered that such an electrode material can exhibit excellent performance as an electrode.

[0021] The above formula is BaZr 1-x-y In x Co y O 3-δ The compound represented by the formula: The following formulas (4) to (7) may be satisfied. Formula (4): 0.125≦y≦0.375 Formula (5): 0.25≦x≦0.5 Formula (6): y≧-x+0.5 Formula (7): y≦-x+0.75

[0022] As shown in Example 1, Example 3, Example 8 to Example 10, and Example 13 to Example 19 described later, the electrode material containing the compound satisfying the above formulas (4) to (7) can be composed of a single compound. In other words, the electrode material containing the compound satisfying the above formulas (4) to (7) does not contain, for example, an oxide derived from a starting material or a starting material of In2O3 (hereinafter referred to as "impurities derived from the starting material"). As shown in Example 1, Example 3, Example 8 to Example 10, and Example 13 to Example 19 described later, such an electrode material has a lower reaction resistance than an electrode material containing impurities derived from a starting material. Therefore, it is considered that such an electrode material can exhibit better performance as an electrode.

[0023] The above formula is BaZr 1-x-y In x Co y O 3-δThe compound represented by the formula: The following formulas (8) to (11) may be satisfied. Formula (8): 0.25≦x≦0.5 Formula (9): y≦0.375 Formula (10): y≦-x+0.75 Formula (11): y ≧ -0.5x + 0.375

[0024] As shown in Examples 1, 9, 10, 14, 16, and 17 described later, an electrode material containing a compound satisfying the above formulas (8) to (11) has a resistance of 0.49 Ω cm 2 (i.e., a reaction resistance value lower than the reaction resistance value of Comparative Example 2 described later). Therefore, it is considered that such an electrode material can exhibit superior performance as an electrode.

[0025] The above formula is BaZr 1-x-y In x Co y O 3-δ The compound represented by the formula (I) may satisfy one formula selected from the group consisting of the following formulas (A1) to (A6). Formula (A1): 0.075≦x≦0.175, and 0.075≦y≦0.175 Formula (A2): 0.200≦x≦0.300, and 0.075≦y≦0.425 Formula (A3): 0.325≦x≦0.425, and 0.075≦y≦0.550 Formula (A4): 0.450≦x≦0.550, and 0.075≦y≦0.425 Formula (A5): 0.575≦x≦0.675, and 0.075≦y≦0.300 Formula (A6): 0.700≦x≦0.800, and 0.075≦y≦0.175

[0026] As shown in Example 1, Example 3, Example 8 to Example 10, and Example 13 to Example 21 described later, an electrode material containing a compound satisfying one of the formulas (A1) to (A6) can be composed of a single compound. In other words, an electrode material containing a compound satisfying one of the formulas (A1) to (A6) does not contain, for example, an oxide derived from a starting material or a starting material of In2O3 (hereinafter referred to as "impurities derived from starting material"). As shown in Example 1, Example 3, Example 8 to Example 10, and Example 13 to Example 21 described later, such an electrode material has a lower reaction resistance than an electrode material containing impurities derived from a starting material. Therefore, it is considered that such an electrode material can exhibit better performance as an electrode.

[0027] The above formula is BaZr 1-x-y In x Co y O 3-δ The compound represented by the formula (A7) may satisfy one formula selected from the group consisting of the following formulas (A7) to (A9). Formula (A7): 0.200≦x≦0.300, and 0.200≦y≦0.425 Formula (A8): 0.325≦x≦0.425, and 0.075≦y≦0.425 Formula (A9): 0.450≦x≦0.550, and 0.075≦y≦0.300

[0028] As shown in Examples 1, 8 to 10, 13, 14, 16, and 17 described later, an electrode material containing a compound satisfying one of the formulae selected from the group consisting of the above formulae (A7) to (A9) has a resistance of 2 Ωcm at 600° C. 2 Therefore, it is believed that such an electrode material can exhibit superior performance as an electrode.

[0029] The above formula is BaZr 1-x-y In x Co y O3-δ The compound represented by the formula (A10) may satisfy one formula selected from the group consisting of the formulas (A10) and (A11) below. Formula (A10): 0.200≦x≦0.300, and 0.200≦y≦0.300 Formula (A11): 0.325≦x≦0.425, and 0.200≦y≦0.425

[0030] As shown in Examples 1, 9, and 14 described later, an electrode material containing a compound satisfying one of the formulae selected from the group consisting of the above formulae (A10) and (A11) has a resistance of 0.13 Ωcm at 600°C. 2 Therefore, it is believed that such an electrode material can exhibit superior performance as an electrode.

[0031] The electrode material according to embodiment 1, like the electrode materials according to examples 1, 3, 8 to 10 and 13 described below, has the chemical formula BaZr 1-x-y In x Co y O 3-δ The compound may be represented by the following formula:

[0032] "The electrode material according to embodiment 1 has the chemical formula BaZr 1-x-y In x Co y O 3-δ "Comprised of a compound represented by the chemical formula BaZr 1-x-y In x Co y O 3-δ The compound represented by the chemical formula BaZr is present in an amount of 90% or more by mole. 1-x-y In x Co y O 3-δ When the electrode material according to embodiment 1 is composed of a compound represented by the formula:

[0033] As an example, the electrode material according to embodiment 1 has the formula BaZr 1-x-y In x Co y O 3-δ The electrode material according to embodiment 1 may be substantially composed of a compound represented by the chemical formula BaZr 1-x-y In x Co y O 3-δ "Comprising a compound represented by the formula BaZr" means that the electrode material according to embodiment 1 is made of a compound represented by the formula BaZr, excluding components contained as unavoidable impurities. 1-x-y In x Co y O 3-δ In this case, in the electrode material according to the first embodiment, the compound represented by the chemical formula BaZr 1-x-y In x Co y O 3-δ The compound represented by the formula (I) may account for 95% or more in terms of molar ratio.

[0034] The electrode material according to embodiment 1 has the above chemical formula BaZr 1-x-y In x Co y O 3-δ In addition to the compound represented by the formula (I), other components may be included. The electrode material according to the first embodiment may further include, as other components, impurities (e.g., BaCO3, ZrO2, or In2O3) generated in the process of synthesizing the above-mentioned compound.

[0035] As described above, the electrode material according to the first embodiment is an electrode material that can be suitably used in particular for the air electrode of an SOFC in which a proton-conductive electrolyte material is used in the electrolyte membrane. However, the electrode material according to the first embodiment can also be used as an electrode material for an SOFC in which the electrolyte membrane is made of an oxide-ion conductor electrolyte material.

[0036] (Embodiment 2) The electrode material according to the second embodiment has the chemical formula BaZr 1-x-y M x Co y O3-δ It contains a compound represented by M being Yb. That is, the electrode material according to Embodiment 1, as shown in Embodiments 22 to 48 described later, has the chemical formula BaZr 1-x-y Yb x Co y O 3-δ and contains a compound represented by. Here, this chemical formula satisfies 0 < x < 1, 0 < y < 1, 0 < (x + y) < 1, and 0 < δ < 1. The electrode material according to Embodiment 1 can have a low reaction resistance at a temperature of about 500°C to 600°C, for example. Therefore, the electrode material according to Embodiment 1 can function as an electrode material that can be used for the electrodes of, for example, SOFC. Note that the electrode material according to Embodiment 1 may satisfy 0 < δ < 0.5.

[0037] The electrode material according to Embodiment 1 may have the following reaction resistance at 600°C, for example, 1 Ωcm 2 When the electrode material according to Embodiment 1 has such a low reaction resistance, the electrode material according to Embodiment 1 can exhibit excellent performance as an electrode.

[0038] The above chemical formula BaZr 1-x-y Yb x Co y O 3-δ The compound represented by has proton conductivity. Therefore, when the electrode material according to Embodiment 1 is used for the air electrode of an SOFC in which an electrolyte material having proton conductivity is used for the electrolyte membrane, not only the air electrode, the electrolyte membrane, and the oxygen contact surface (that is, the three-phase interface of the air electrode, the electrolyte membrane, and oxygen), but also the air electrode and the oxygen contact surface (that is, the two-phase interface of the air electrode and oxygen) can be used as reaction fields. Therefore, when the electrode material according to Embodiment 1 is used for the electrodes of an SOFC in which an electrolyte material having proton conductivity is used for the electrolyte membrane, for example, it can exhibit excellent performance as an electrode.

[0039] The electrode material according to Embodiment 1, for example, the above chemical formula BaZr 1-x-y Yb x Co y O3-δ The compound represented by the chemical formula BaZr may be contained in an amount of 30% or more, or 50% or more by mole. 1-x-y Yb x Co y O 3-δ By containing the compound represented by the formula (1), the electrode material according to the embodiment 1 can exhibit more excellent performance as an electrode.

[0040] The above formula is BaZr 1-x-y Yb x Co y O 3-δ The compound represented by the formula (12) may satisfy the following formulas (12) and (13). Formula (12): 0.075≦x≦0.625 Formula (13): 0.125≦y

[0041] As shown in Examples 22 to 41 and Examples 43 to 48 described later, an electrode material containing a compound satisfying the above formulas (12) and (13) has a reaction resistance of 1.42 Ω cm at 600 ° C. 2 (i.e., a reaction resistance value lower than the reaction resistance value of Comparative Example 3 described later). Therefore, it is considered that such an electrode material can exhibit superior performance as an electrode.

[0042] The above formula is BaZr 1-x-y Yb x Co y O 3-δ The compound represented by the formula (14) may satisfy the following formulas (14) and (15). Formula (14): y≦12.5x-0.6875 Formula (15): y≧x-0.375

[0043] As shown in Example 22, Example 24 to Example 41, and Example 43 to Example 44 described later, an electrode material containing a compound satisfying the above formulas (14) and (15) can be composed of a single compound. In other words, an electrode material containing a compound satisfying the above formulas (14) and (15) can be an electrode material that does not contain, for example, oxides derived from the starting materials (hereinafter referred to as "impurities derived from the starting materials"). That is, when a compound satisfying the above formulas (14) and (15) is contained, an electrode material having good performance, particularly without a by-product phase, can be provided. "Without a by-product phase" here means that components other than the components constituting the target electrode material cannot be confirmed by X-ray diffraction. Therefore, this does not include the inclusion of other components at the impurity level. Such an electrode material is considered to have a lower reaction resistance than an electrode material containing impurities derived from the starting materials. Therefore, such an electrode material is considered to be able to exhibit better performance as an electrode.

[0044] The above formula is BaZr 1-x-y Yb x Co y O 3-δ The compound represented by the formula (16) may satisfy the following formulas (17). Formula (16): y≧-2.5x+0.4375 Formula (17): y≧x-0.375

[0045] When the compound satisfying the above formulas (16) and (17) is contained, an electrode material having no by-product phase and further excellent electrode performance can be provided. As shown in Examples 22, 25 to 41, and 44 described later, the electrode material containing the compound satisfying the above formulas (16) and (17) has a reaction resistance of 0.49 Ω cm at 600°C. 2 The electrode material can have a low reaction resistance value below 100 nm (i.e., a reaction resistance value lower than the reaction resistance value of Comparative Example 2 described later). Therefore, it is considered that such an electrode material can exhibit superior performance as an electrode.

[0046] The above formula is BaZr1-x-y Yb x Co y O 3-δ The compound represented by the formula (B1) may satisfy one formula selected from the group consisting of the following formulas (B1) to (B5). Formula (B1): 0.075≦x≦0.175 and 0.075≦y≦0.800 Formula (B2): 0.200≦x≦0.300, and 0.075≦y≦0.675 Formula (B3): 0.325≦x≦0.425, and 0.075≦y≦0.550 Formula (B4): 0.450≦x≦0.550, and 0.075≦y≦0.425 Formula (B5): 0.575≦x≦0.675, and 0.200≦y≦0.300

[0047] As shown in Example 22, Example 24 to Example 41, Example 43, and Example 44 described later, an electrode material containing a compound satisfying one of the formulae selected from the group consisting of the above formulae (B1) to (B5) can be composed of a single compound. In other words, an electrode material containing a compound satisfying one of the formulae selected from the group consisting of the above formulae (B1) to (B5) can be an electrode material that does not contain impurities derived from, for example, the starting material. That is, when a compound satisfying one of the formulae selected from the group consisting of the above formulae (B1) to (B5) is contained, an electrode material having good performance, particularly without a by-product phase, can be provided. Therefore, the inclusion of other components at the impurity level is not limited to this. Such an electrode material is considered to have a lower reaction resistance than an electrode material containing impurities derived from the starting material. Therefore, such an electrode material is considered to be able to exhibit better performance as an electrode.

[0048] The above formula is BaZr 1-x-y Yb x Co y O 3-δ The compound represented by the formula (B6) may satisfy one formula selected from the group consisting of the following formulas (B10): Formula (B6): 0.075≦x≦0.175, and 0.200≦y≦0.800 Formula (B7): 0.200≦x≦0.300, and 0.075≦y≦0.675 Formula (B8): 0.325≦x≦0.425, and 0.075≦y≦0.550 Formula (B9): 0.450≦x≦0.550, and 0.075≦y≦0.425 Formula (B10): 0.575≦x≦0.675, and 0.200≦y≦0.300

[0049] When a compound satisfying one of the formulae selected from the group consisting of the above formulae (B6) to (B10) is contained, an electrode material having no by-product phase and better electrode performance can be provided. As shown in Examples 22, 25 to 41, and 44 described later, an electrode material containing a compound satisfying one of the formulae selected from the group consisting of the above formulae (B6) to (B10) has a reaction resistance of 0.50 Ωcm at 600°C. 2 It is believed that such an electrode material can exhibit superior performance as an electrode.

[0050] The above formula is BaZr 1-x-y Yb x Co y O 3-δ The compound represented by the formula (B11) may satisfy one formula selected from the group consisting of the following formulas (B14): Formula (B11): 0.075≦x≦0.175, and 0.200≦y≦0.800 Formula (B12): 0.200≦x≦0.300, and 0.200≦y≦0.675 Formula (B13): 0.325≦x≦0.425, and 0.075≦y≦0.425 Formula (B14): 0.450≦x≦0.550, and 0.200≦y≦0.425

[0051] When a compound satisfying one of the formulae selected from the group consisting of the above formulae (B11) to (B14) is contained, an electrode material having no by-product phase and further excellent electrode performance can be provided. As shown in Examples 22, 25 to 29, 31 to 36, 39, and 40 described later, an electrode material containing a compound satisfying one of the formulae selected from the group consisting of the above formulae (11) to (14) has a reaction resistance of 0.20 Ωcm at 600°C. 2 It is believed that such an electrode material can exhibit superior performance as an electrode.

[0052] The above formula is BaZr 1-x-y Yb x Co y O 3-δ The compound represented by the formula (B15) may satisfy one formula selected from the group consisting of the following formulas (B18) to (B18). Formula (15): 0.075≦x≦0.175 and 0.325≦y≦0.425 Formula (16): 0.075≦x≦0.175 and 0.575≦y≦0.800 Formula (17): 0.200≦x≦0.300 and 0.200≦y≦0.425 Formula (18): 0.325≦x≦0.425 and 0.200≦y≦0.425

[0053] When a compound satisfying one of the formulae selected from the group consisting of the above formulae (B15) to (B18) is contained, an electrode material having no by-product phase and particularly excellent electrode performance can be provided. As shown in Examples 22, 27, 28, 29, 31, 35, and 36 described later, an electrode material containing a compound satisfying one of the formulae selected from the group consisting of the above formulae (B15) to (B18) has a reaction resistance of 0.13 Ωcm at 600°C. 2 (i.e., a reaction resistance value lower than the reaction resistance value of Comparative Example 3 described later). Therefore, it is considered that such an electrode material has particularly excellent performance as an electrode material.

[0054] The electrode material according to embodiment 1, like the electrode materials according to examples 22, 24 to 41, 43 and 44 described below, has the chemical formula BaZr 1-x-y Yb x Co y O 3-δ According to this configuration, an electrode material without a by-product phase can be provided.

[0055] "The electrode material according to embodiment 1 has the chemical formula BaZr 1-x-y Yb x Co y O 3-δ "Comprised of a compound represented by the chemical formula BaZr 1-x-y Yb x Co y O 3-δ The compound represented by the chemical formula BaZr is present in an amount of 90% or more by mole. 1-x-y Yb x Co y O 3-δ When the electrode material according to embodiment 1 is composed of a compound represented by the formula:

[0056] As an example, the electrode material according to embodiment 2 has the formula BaZr 1-x-y Yb x Co y O 3-δ The electrode material according to embodiment 1 may be substantially composed of a compound represented by the chemical formula BaZr 1-x-y Yb x Co y O 3-δ "Comprising a compound represented by the formula BaZr" means that the electrode material according to embodiment 1 is made of a compound represented by the formula BaZr, excluding components contained as unavoidable impurities. 1-x-y Yb x Co y O 3-δ In this case, in the electrode material according to the first embodiment, the compound represented by the chemical formula BaZr 1-x-yYb x Co y O 3-δ The compound represented by the formula (I) may account for 95% or more in terms of molar ratio.

[0057] The electrode material according to the first embodiment has the above chemical formula BaZr 1-x-y Yb x Co y O 3-δ In addition to the compound represented by the formula (I), other components may be included. The electrode material according to the first embodiment may further include, for example, impurities generated in the process of synthesizing the above-described compound, or metal oxides, as other components.

[0058] As described above, the electrode material according to the second embodiment is an electrode material that can be suitably used in the air electrode of a SOFC in which a proton-conductive electrolyte material is used in the electrolyte membrane. However, the electrode material according to the first embodiment can also be used as an electrode material for a SOFC in which the electrolyte membrane is made of an oxide-ion conductor electrolyte material.

[0059] (Embodiment 3) 1A shows a cross-sectional view of a membrane electrode assembly 10 according to embodiment 3. The membrane electrode assembly 10 includes an electrolyte membrane 11 and a first electrode 12. In other words, the electrolyte membrane 11 is provided on a first main surface 12a of the first electrode 12.

[0060] The membrane electrode assembly 10 according to the third embodiment is used, for example, in a fuel cell. When the membrane electrode assembly 10 is used in a fuel cell, the first electrode 12 in the membrane electrode assembly 10 is, for example, an air electrode.

[0061] The electrolyte membrane 11 is made of, for example, an electrolyte material having proton conductivity (i.e., a proton conductor). An example of the proton conductor is represented by the chemical formula BaZr 1-x1 M1 x1 O 3-δ The compound represented by the chemical formula BaCe 1-x2 M2 x2 O 3-δ Compounds represented by the formula BaZr1-x3-y3 Ce x3 M3 y3 O 3-δ is a compound represented by. Here, M1, M2, and M3 each contain at least one selected from the group consisting of Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Y, Sc, In, and Lu, and 0 < x1 < 1, 0 < x2 < 1, 0 < x3 < 1, 0 < y3 < 1, and 0 < δ < 0.5 are satisfied. However, the proton conductor is not limited to this. The electrolyte membrane 11 of the membrane electrode assembly 10 according to Embodiment 2 is, for example, the chemical formula BaZr 1-x1 M1 x1 O 3-δ a compound represented by, the chemical formula BaCe 1-x2 M2 x2 O 3-δ a compound represented by and the chemical formula BaZr 1-x3-y3 Ce x3 M3 y3 O 3-δ a compound represented by, and contains at least one selected from the group consisting of. M1 may be Yb.

[0062] According to the above configuration, a membrane electrode assembly 10 composed of a material having excellent proton conductivity as an electrolyte and an electrode material having excellent electrode characteristics can be provided.

[0063] The electrolyte membrane 11 may contain a material having proton conductivity as described above, or may contain an oxide ion conductor. Examples of the oxide ion conductor are yttria-stabilized zirconia, scandia-stabilized zirconia, gadolinium-doped ceria, or lanthanum strontium gallium magnesium composite oxide, etc.

[0064] The thickness of the electrolyte membrane 11 is, for example, from 1 to 500 μm, and may be from 1 to 50 μm.

[0065] The first electrode 12 includes the electrode material described in embodiment 1 or embodiment 2. This configuration allows the membrane electrode assembly 10 according to embodiment 2 to have excellent electrode activity. The first electrode 12 may be composed of the electrode material described in embodiment 1 alone, or may be composed of, for example, a mixture of the electrode material according to embodiment 2 and a metal or a metal oxide. The first electrode 12 may be composed of the electrode material described in embodiment 2 alone, or may be composed of, for example, a mixture of the electrode material according to embodiment 2 and a metal or a metal oxide.

[0066] The first electrode 12 has a thickness of, for example, 1 to 1000 μm. When the first electrode 12 also serves as a support for the cell, the first electrode 12 may have a thickness of 100 μm to 1000 μm. When a component other than the first electrode 12 serves as a support for the cell, the first electrode 12 may have a thickness of 1 μm to 100 μm, or may have a thickness of 5 to 50 μm.

[0067] The electrode materials described in the first and second embodiments have proton conductivity. Therefore, when the electrolyte membrane 11 includes a proton conductor, the membrane electrode assembly 10 according to the third embodiment can be used as the air electrode and electrolyte membrane of a SOFC in which an electrolyte material having proton conductivity is used for the electrolyte membrane. Therefore, when the membrane electrode assembly 10 is used as the air electrode and electrolyte membrane of a SOFC, the SOFC can use not only the air electrode, the electrolyte membrane, and the oxygen contact surface (i.e., the three-phase interface of the air electrode, the electrolyte membrane, and oxygen), but also the air electrode and the oxygen contact surface (i.e., the two-phase interface of the air electrode and oxygen) as reaction fields. Therefore, the membrane electrode assembly 10 according to the second embodiment can improve the performance of a SOFC in which an electrolyte material having proton conductivity is used for the electrolyte membrane.

[0068] In FIG. 1A, the electrolyte membrane 11 and the first electrode 12 are in contact with each other. However, another layer may be provided between the electrolyte membrane 11 and the first electrode 12. An example of the another layer is a functional layer. The functional layer is a layer that promotes the movement of electrons or protons between the electrolyte membrane 11 and the first electrode 12. The functional layer is made of, for example, a composite of a cermet and a complex oxide.

[0069] The electrolyte membrane 11 is produced by, for example, a tape casting method, a spin coating method, a dip coating method, a sputtering method, or a PLD (Pulse Laser Deposition) method.

[0070] (Embodiment 4) FIG. 1B shows a cross-sectional view of an electrochemical cell 20 according to embodiment 4.

[0071] The electrochemical cell 20 according to the fourth embodiment includes a membrane electrode assembly 10 and a second electrode 13. That is, the electrochemical cell 20 includes a first electrode 12, an electrolyte membrane 11, and a second electrode 13.

[0072] The membrane electrode assembly 10 is described in the third embodiment.

[0073] 1B, in the electrochemical cell 20, a first electrode 12, an electrolyte membrane 11, and a second electrode 13 are provided in this order. That is, the electrolyte membrane 11 is sandwiched between the first electrode 12 and the second electrode 13. In other words, the electrolyte membrane 11 is provided between the first electrode 12 and the second electrode 13.

[0074] The electrochemical cell 20 according to the fourth embodiment has the above-mentioned configuration and thus can have excellent electrode activity.

[0075] As described in the third embodiment, the first electrode 12 of the membrane electrode assembly 10 may be an air electrode. Therefore, the second electrode 13 may be an anode. When the second electrode 13 functions as an anode, the second electrode 13 includes, for example, a metal oxide. For example, the second electrode 13 mainly includes nickel oxide. The second electrode 13 may be provided on the membrane electrode assembly 10 by, for example, a screen printing method. When the second electrode 13 functions as an anode, the second electrode 13 includes, for example, at least one selected from the group consisting of a metal and a metal oxide. For example, the second electrode 13 includes at least one selected from the group consisting of nickel (i.e., Ni) and nickel oxide (i.e., NiO). This configuration can provide an electrochemical cell 20 with excellent anode performance.

[0076] The second electrode 13 can be applied to the membrane electrode assembly 10 by, for example, tape casting, spin coating, dip coating, sputtering, PLD, or screen printing.

[0077] 1B, the second electrode 13 and the electrolyte membrane 11 are provided in contact with each other, but this is not limiting. Another layer may be provided between the second electrode 13 and the electrolyte membrane 11.

[0078] The other layer can be, for example, a functional layer, which is described in the third embodiment.

[0079] The electrochemical cell 20 may be used in fuel cells, electrochemical hydrogen pumps, hydrogen sensors and water electrolysis devices.

[0080] (Embodiment 5) FIG. 2 shows a schematic diagram of a fuel cell system 1000 according to a fifth embodiment.

[0081] The fuel cell system 1000 includes an electrochemical cell 20. The electrochemical cell 20 is described in the fourth embodiment.

[0082] In the fuel cell system 1000 according to the fifth embodiment, the electrochemical cell 20 is used as a fuel cell. Therefore, in this case, the first electrode 12 functions as an air electrode, and the second electrode 13 functions as a fuel electrode.

[0083] The fuel cell system 1000 further includes an oxidizing gas supply path 1024 and a raw material gas supply path 1023. The oxidizing gas supply path 1024 is connected to the first electrode 12 and the oxidizing gas supplier 1021. The raw material gas supply path 1023 is connected to the second electrode 13 and the raw material supplier 1022.

[0084] The electrochemical cells 20 are stacked to obtain a stack 30. The obtained stack 30 is stored in a housing 1014.

[0085] The housing 1014 may be made of a heat insulating material. An oxidant gas is supplied to the first electrodes 12 of the stacked electrochemical cells 20.

[0086] Specifically, the oxidant gas is supplied from an oxidant gas supplier 1021 through an oxidant gas supply path 1024 to the first electrodes 12 (ie, cathodes) of the multiple electrochemical cells 20.

[0087] At the first electrode 12, the following reaction (1) proceeds. O2+4H + +4e - →2H2O (1)

[0088] The oxidant gas is, for example, air.

[0089] The raw material is supplied from a raw material supplier 1022 through a raw material gas supply path 1023 to the second electrodes 13 of the multiple electrochemical cells 20 .

[0090] At the second electrode 13, the following reaction (2) proceeds. 2H2→4H + +4e - (2)

[0091] The raw material is, for example, hydrogen molecules.

[0092] The hydrogen may be produced by a reforming reaction. Alternatively, the hydrogen may be produced by water electrolysis.

[0093] In this manner, the fuel cell system 1000 operates and generates power.

[0094] The fuel cell system 1000 according to the fifth embodiment can function as a fuel cell having excellent electrode activity at the air electrode.

[0095] (Example) The present disclosure will now be described in more detail with reference to the following examples and comparative examples. As described below, in the examples and comparative examples, electrode materials, membrane electrode assemblies including the electrodes, and electrochemical cells including the membrane electrode assemblies were prepared. The crystal structure of each electrode material was analyzed, and the characteristics of each membrane electrode assembly and each electrochemical cell were evaluated.

[0096] [Example 1] (Preparation of electrode materials) The following materials were prepared as starting materials for the electrode materials: BaCO3 (0.200 mol, manufactured by Kanto Chemical Co., Ltd.) ZrO2 (0.075 mol, manufactured by Kanto Chemical Co., Ltd.) In2O3 (0.038 mol, manufactured by Kojundo Chemical Laboratory Co., Ltd.) Co3O4 (0.017 mol, manufactured by Kanto Chemical Co., Ltd.)

[0097] The starting materials and 50 mL of distilled water were added to a 250 mL container. Next, the container was stirred at 200 rpm for 10 minutes using a planetary ball mill (manufactured by Fritsch). This stirring process was repeated twice. In this way, a mixed liquid was obtained. The mixed liquid obtained was dried at 120°C for 6 hours in a dryer (MOV-212F, manufactured by Panasonic) to remove moisture from the mixed liquid. In this way, a solid was obtained. The obtained solid was crushed in a mortar, and the obtained powder was transferred to an alumina crucible (manufactured by Nikkato Corporation). The alumina crucible was then fired at a temperature of 1300°C in an air atmosphere for 2 hours. In this way, an electrode material was obtained. Table 1 shows the chemical formula BaZr 1-x-y In x Co y O 3-δ The x and y values ​​in are shown.

[0098] (X-ray diffraction of electrode materials) The X-ray diffraction device "Smartlab" (manufactured by Rigaku) ​​was used to analyze the crystal structure of the obtained electrode material. Specifically, CuKα radiation was used as the X-ray source, and the obtained electrode material was irradiated with X-rays using the parallel beam method. Using the known BaZrO3 peak (database: refer to the ICDD database) as a reference, it was confirmed that an oxide with the desired composition had been synthesized.

[0099] (Fabrication of membrane electrode assembly) Next, a method for producing the membrane electrode assembly will be described.

[0100] First, BaZr 0.8 Yb 0.2 O 3-δ The electrolyte membrane was fabricated using BaZr 0.8 Yb 0.2 O 3-δ Next, about 10 g of the electrolyte material BaZr 0.8 Yb 0.2 O 3-δThe mixture was pressed into a cylindrical shape to obtain a pellet. The obtained pellet was put into a bag and packed. Then, it was pressed at 200 MPa for 3 minutes by cold isostatic pressing (i.e., "CIP"). In this way, a molded body was obtained. The obtained molded body was fired at 1750°C for 24 hours under atmospheric conditions to obtain a sintered body. The obtained sintered body was polished using a wrapping film (manufactured by 3M) having a grain size of 15 microns. After being polished, the obtained sintered body had a thickness of about 500 μm. In this way, an electrolyte membrane was produced. The electrolyte membrane had two main surfaces (i.e., a first main surface and a second main surface).

[0101] Next, a first electrode was prepared. In order to prepare the first electrode by applying the electrode material prepared by the above-mentioned method to the first main surface of the electrolyte membrane, a paste containing the electrode material was prepared by the following method.

[0102] The following materials were prepared as starting materials for the paste: ·Electrode material 20g EC vehicle (manufactured by Nisshin Chemical Industry Co., Ltd.) 13.3g

[0103] The electrode material and the EC vehicle were added to a plastic container. The mixture was stirred at 1000 rpm for 5 minutes using a planetary centrifugal mixer. In this way, a paste precursor was obtained. The paste precursor obtained was dispersed using a three-roll mill (product name: BR-100VIII, manufactured by Imex). In this way, an electrode dispersion liquid was obtained.

[0104] The obtained electrode dispersion was printed by screen printing at the center of the first main surface of the electrolyte membrane prepared by the above method. The first electrode thus prepared was circular and had a diameter of 10 mm. In this manner, a membrane electrode assembly was prepared.

[0105] (Preparation of evaluation cells) Next, a method for preparing an evaluation cell for evaluating electrode activity will be described.

[0106] First, a membrane electrode assembly for evaluation was produced using the membrane electrode assembly produced by the above-mentioned method.

[0107] The electrode dispersion liquid was also printed on the second main surface of the electrolyte membrane constituting the membrane electrode assembly. Next, the membrane electrode assembly on which the electrode dispersion liquid was printed was baked in an air atmosphere at 1000°C (hereinafter referred to as the "electrode baking temperature") for 2 hours. In this manner, a membrane electrode assembly for evaluation was obtained.

[0108] Next, an evaluation cell was fabricated using the obtained membrane electrode assembly for evaluation. The following method was used to evaluate the electrode activity using the fabricated membrane electrode assembly for evaluation. The following items were prepared to fabricate the evaluation cell. Membrane electrode assembly for evaluation Silver ink (manufactured by Toyo Corporation)

[0109] Using a screen printing method, silver ink was printed on the electrodes on both sides of the membrane electrode assembly for evaluation. In this way, a precursor of the evaluation cell was obtained. The printed silver ink had a diameter of 10 mm. The obtained precursor of the evaluation cell was then fired in an air atmosphere at 800° C. for 1 hour. In this way, the evaluation cell was produced.

[0110] (Measurement of reaction resistance using an evaluation cell) The reaction resistance of the evaluation cell was measured.

[0111] Air (flow rate: 100 mL / min) humidified to a dew point temperature of 20°C was passed through the evaluation cell, and the reaction resistance of the evaluation cell was measured based on the AC impedance method performed at a temperature of 600°C.

[0112] Specifically, an AC signal was applied to the cell with an amplitude of 10 mV in the range of 1 MHz to 0.01 Hz using ModuLab XM ECS (manufactured by Solartron Analytical). For an arc drawn in the frequency range of approximately 100 kHz to 0.01 Hz in the Nyquist plot, the real number was calculated from the intersection of the arc and the real axis on the high frequency side to the low frequency end. In a fuel cell, the semicircular waveform obtained as the reaction resistance in the AC impedance method is usually observed separately for the positive and negative electrodes. However, in this measurement, an evaluation cell made of the same material on both sides is used. Therefore, in the results obtained in this measurement, the current response of the air electrode is displayed overlapping. Therefore, in order to consider the electrode activity per side, the real number was halved, and this halved real number was taken as the reaction resistance. The reaction resistance is the energy loss required for electron transfer in the electrochemical reaction at the electrode. The calculated resistance is considered to have a correlation with the activity of the electrode. Therefore, the electrode activity was judged based on the magnitude of the calculated resistance.

[0113] For specific methods of evaluating reaction resistance, see below. (i) When an intersection point between the arc and the real axis on the high frequency side (e.g., I1 in Figure 8) is observed in the Nyquist plot of a circular arc drawn in the frequency range of approximately 100 kHz to 0.01 Hz, The real number (e.g., R1 shown in FIG. 8) from the intersection point of the arc and the real axis on the high frequency side to the low frequency end (e.g., I2 shown in FIG. 8) was obtained. Then, the real number was taken as the reaction resistance. (ii) In the Nyquist plot, for a circular arc drawn in the frequency range of approximately 100 kHz to 0.01 Hz, no intersection point is observed between the circular arc and the real axis on the high frequency side. The real number from the minimum point of the arc to the low frequency end (for example, R2 in Figure 9) was calculated, and this real number was taken as the reaction resistance.

[0114] [Example 2] In Example 2, the electrode material, the membrane electrode assembly, and the evaluation cell were prepared, and the crystal structure of the electrode material was analyzed, in the same manner as in Example 1, except for the following items (1) and (2). (1) The starting materials for the electrode materials have been changed to the following materials: BaCO3 (0.200 mol, manufactured by Kanto Chemical Co., Ltd.) ZrO2 (0.050 mol, manufactured by Kanto Chemical Co., Ltd.) In2O3 (0.013 mol, manufactured by Kojundo Chemical Laboratory Co., Ltd.) Co3O4 (0.042 mol, manufactured by Kanto Chemical Co., Ltd.) (2) Calcination of the electrode materials was carried out at temperatures of 1100°C, 1200°C and 1300°C.

[0115] [Example 3] In Example 3, the electrode material, the membrane electrode assembly, and the evaluation cell were prepared, the crystal structure of the electrode material was analyzed, and the reaction resistance was measured using the evaluation cell in the same manner as in Example 1, except for the following item (1). (1) The starting materials for the electrode materials have been changed to the following materials: BaCO3 (0.200 mol, manufactured by Kanto Chemical Co., Ltd.) ZrO2 (0.150 mol, manufactured by Kanto Chemical Co., Ltd.) In2O3 (0.013 mol, manufactured by Kojundo Chemical Laboratory Co., Ltd.) Co3O4 (0.008 mol, manufactured by Kanto Chemical Co., Ltd.)

[0116] [Example 4] In Example 4, the electrode material, the membrane electrode assembly, and the evaluation cell were produced, and the crystal structure of the electrode material was analyzed, in the same manner as in Example 1, except for the following item (1). (1) The starting materials for the electrode materials have been changed to the following materials: BaCO3 (0.200 mol, manufactured by Kanto Chemical Co., Ltd.) ZrO2 (0.125 mol, manufactured by Kanto Chemical Co., Ltd.) In2O3 (0.012 mol, manufactured by Kojundo Chemical Laboratory Co., Ltd.) Co3O4 (0.017 mol, manufactured by Kanto Chemical Co., Ltd.)

[0117] [Example 5] In Example 5, the electrode material, the membrane electrode assembly, and the evaluation cell were produced, and the crystal structure of the electrode material was analyzed, in the same manner as in Example 1, except for the following item (1). (1) The starting materials for the electrode materials have been changed to the following materials: BaCO3 (0.200 mol, manufactured by Kanto Chemical Co., Ltd.) ZrO2 (0.100 mol, manufactured by Kanto Chemical Co., Ltd.) In2O3 (0.012 mol, manufactured by Kojundo Chemical Laboratory Co., Ltd.) Co3O4 (0.025 mol, manufactured by Kanto Chemical Co., Ltd.)

[0118] [Example 6] In Example 6, the electrode material, the membrane electrode assembly, and the evaluation cell were produced, and the crystal structure of the electrode material was analyzed, in the same manner as in Example 1, except for the following item (1). (1) The starting materials for the electrode materials have been changed to the following materials: BaCO3 (0.200 mol, manufactured by Kanto Chemical Co., Ltd.) ZrO2 (0.075 mol, manufactured by Kanto Chemical Co., Ltd.) In2O3 (0.013 mol, manufactured by Kojundo Chemical Laboratory Co., Ltd.) Co3O4 (0.033 mol, manufactured by Kanto Chemical Co., Ltd.)

[0119] [Example 7] In Example 7, the electrode material, the membrane electrode assembly, and the evaluation cell were produced, and the crystal structure of the electrode material was analyzed, in the same manner as in Example 1, except for the following item (1). (1) The starting materials for the electrode materials have been changed to the following materials: BaCO3 (0.200 mol, manufactured by Kanto Chemical Co., Ltd.) ZrO2 (0.025 mol, manufactured by Kanto Chemical Co., Ltd.) In2O3 (0.012 mol, manufactured by Kojundo Chemical Laboratory Co., Ltd.) Co3O4 (0.050 mol, manufactured by Kanto Chemical Co., Ltd.)

[0120] [Example 8] In Example 8, the electrode material, the membrane electrode assembly, and the evaluation cell were prepared, the crystal structure of the electrode material was analyzed, and the reaction resistance was measured using the evaluation cell in the same manner as in Example 1, except for the following item (1). (1) The starting materials for the electrode materials have been changed to the following materials: BaCO3 (0.200 mol, manufactured by Kanto Chemical Co., Ltd.) ZrO2 (0.125 mol, manufactured by Kanto Chemical Co., Ltd.) In2O3 (0.025 mol, manufactured by Kojundo Chemical Laboratory Co., Ltd.) Co3O4 (0.083 mol, manufactured by Kanto Chemical Co., Ltd.)

[0121] [Example 9] In Example 9, the electrode material, the membrane electrode assembly, and the evaluation cell were prepared, the crystal structure of the electrode material was analyzed, and the reaction resistance was measured using the evaluation cell in the same manner as in Example 1, except for the following item (1). (1) The starting materials for the electrode materials have been changed to the following materials: BaCO3 (0.200 mol, manufactured by Kanto Chemical Co., Ltd.) ZrO2 (0.100 mol, manufactured by Kanto Chemical Co., Ltd.) In2O3 (0.025 mol, manufactured by Kojundo Chemical Laboratory Co., Ltd.) Co3O4 (0.017 mol, manufactured by Kanto Chemical Co., Ltd.)

[0122] [Example 10] In Example 10, the electrode material, the membrane electrode assembly, and the evaluation cell were prepared, the crystal structure of the electrode material was analyzed, and the reaction resistance was measured using the evaluation cell in the same manner as in Example 1, except for the following item (1). (1) The starting materials for the electrode materials have been changed to the following materials: BaCO3 (0.200 mol, manufactured by Kanto Chemical Co., Ltd.) ZrO2 (0.075 mol, manufactured by Kanto Chemical Co., Ltd.) In2O3 (0.025 mol, manufactured by Kojundo Chemical Laboratory Co., Ltd.) Co3O4 (0.025 mol, manufactured by Kanto Chemical Co., Ltd.)

[0123] [Example 11] In Example 11, the electrode material, the membrane electrode assembly, and the evaluation cell were produced, and the crystal structure of the electrode material was analyzed, in the same manner as in Example 1, except for the following item (1). (1) The starting materials for the electrode materials have been changed to the following materials: BaCO3 (0.200 mol, manufactured by Kanto Chemical Co., Ltd.) ZrO2 (0.050 mol, manufactured by Kanto Chemical Co., Ltd.) In2O3 (0.025 mol, manufactured by Kojundo Chemical Laboratory Co., Ltd.) Co3O4 (0.033 mol, manufactured by Kanto Chemical Co., Ltd.)

[0124] [Example 12] In Example 12, the electrode material, the membrane electrode assembly, and the evaluation cell were produced, and the crystal structure of the electrode material was analyzed, in the same manner as in Example 1, except for the following item (1). (1) The starting materials for the electrode materials have been changed to the following materials: BaCO3 (0.200 mol, manufactured by Kanto Chemical Co., Ltd.) ZrO2 (0.025 mol, manufactured by Kanto Chemical Co., Ltd.) In2O3 (0.025 mol, manufactured by Kojundo Chemical Laboratory Co., Ltd.) Co3O4 (0.042 mol, manufactured by Kanto Chemical Co., Ltd.)

[0125] [Example 13] In Example 13, the electrode material, the membrane electrode assembly, and the evaluation cell were prepared, the crystal structure of the electrode material was analyzed, and the reaction resistance was measured using the evaluation cell in the same manner as in Example 1, except for the following item (1). (1) The starting materials for the electrode materials have been changed to the following materials: BaCO3 (0.200 mol, manufactured by Kanto Chemical Co., Ltd.) ZrO2 (0.100 mol, manufactured by Kanto Chemical Co., Ltd.) In2O3 (0.038 mol, manufactured by Kojundo Chemical Laboratory Co., Ltd.) Co3O4 (0.008 mol, manufactured by Kanto Chemical Co., Ltd.)

[0126] [Example 14] In Example 14, the electrode material, the membrane electrode assembly, and the evaluation cell were prepared, the crystal structure of the electrode material was analyzed, and the reaction resistance was measured using the evaluation cell in the same manner as in Example 1, except for the following item (1). (1) The starting materials for the electrode materials have been changed to the following materials: BaCO3 (0.200 mol, manufactured by Kanto Chemical Co., Ltd.) ZrO2 (0.050 mol, manufactured by Kanto Chemical Co., Ltd.) In2O3 (0.038 mol, manufactured by Kojundo Chemical Laboratory Co., Ltd.) Co3O4 (0.025 mol, manufactured by Kanto Chemical Co., Ltd.)

[0127] [Example 15] In Example 15, the electrode material, the membrane electrode assembly, and the evaluation cell were produced, and the crystal structure of the electrode material was analyzed, in the same manner as in Example 1, except for the following item (1). (1) The starting materials for the electrode materials have been changed to the following materials: BaCO3 (0.200 mol, manufactured by Kanto Chemical Co., Ltd.) ZrO2 (0.025 mol, manufactured by Kanto Chemical Co., Ltd.) In2O3 (0.038 mol, manufactured by Kojundo Chemical Laboratory Co., Ltd.) Co3O4 (0.033 mol, manufactured by Kanto Chemical Co., Ltd.)

[0128] [Example 16] In Example 16, the electrode material, the membrane electrode assembly, and the evaluation cell were prepared, the crystal structure of the electrode material was analyzed, and the reaction resistance was measured using the evaluation cell in the same manner as in Example 1, except for the following item (1). (1) The starting materials for the electrode materials have been changed to the following materials: BaCO3 (0.200 mol, manufactured by Kanto Chemical Co., Ltd.) ZrO2 (0.075 mol, manufactured by Kanto Chemical Co., Ltd.) In2O3 (0.050 mol, manufactured by Kojundo Chemical Laboratory Co., Ltd.) Co3O4 (0.008 mol, manufactured by Kanto Chemical Co., Ltd.)

[0129] [Example 17] In Example 17, the electrode material, the membrane electrode assembly, and the evaluation cell were prepared, the crystal structure of the electrode material was analyzed, and the reaction resistance was measured using the evaluation cell in the same manner as in Example 1, except for the following item (1). (1) The starting materials for the electrode materials have been changed to the following materials: BaCO3 (0.200 mol, manufactured by Kanto Chemical Co., Ltd.) ZrO2 (0.050 mol, manufactured by Kanto Chemical Co., Ltd.) In2O3 (0.050 mol, manufactured by Kojundo Chemical Laboratory Co., Ltd.) Co3O4 (0.017 mol, manufactured by Kanto Chemical Co., Ltd.)

[0130] [Example 18] In Example 18, the electrode material, the membrane electrode assembly, and the evaluation cell were produced, and the crystal structure of the electrode material was analyzed, in the same manner as in Example 1, except for the following item (1). (1) The starting materials for the electrode materials have been changed to the following materials: BaCO3 (0.200 mol, manufactured by Kanto Chemical Co., Ltd.) ZrO2 (0.025 mol, manufactured by Kanto Chemical Co., Ltd.) In2O3 (0.050 mol, manufactured by Kojundo Chemical Laboratory Co., Ltd.) Co3O4 (0.025 mol, manufactured by Kanto Chemical Co., Ltd.)

[0131] [Example 19] In Example 19, the electrode material, the membrane electrode assembly, and the evaluation cell were prepared, the crystal structure of the electrode material was analyzed, and the reaction resistance was measured using the evaluation cell in the same manner as in Example 1, except for the following item (1). (1) The starting materials for the electrode materials have been changed to the following materials: BaCO3 (0.200 mol, manufactured by Kanto Chemical Co., Ltd.) ZrO2 (0.050 mol, manufactured by Kanto Chemical Co., Ltd.) In2O3 (0.063 mol, manufactured by Kojundo Chemical Laboratory Co., Ltd.) Co3O4 (0.008 mol, manufactured by Kanto Chemical Co., Ltd.)

[0132] [Example 20] In Example 20, the electrode material, the membrane electrode assembly, and the evaluation cell were produced, and the crystal structure of the electrode material was analyzed, in the same manner as in Example 1, except for the following item (1). (1) The starting materials for the electrode materials have been changed to the following materials: BaCO3 (0.200 mol, manufactured by Kanto Chemical Co., Ltd.) ZrO2 (0.025 mol, manufactured by Kanto Chemical Co., Ltd.) In2O3 (0.062 mol, manufactured by Kojundo Chemical Laboratory Co., Ltd.) Co3O4 (0.017 mol, manufactured by Kanto Chemical Co., Ltd.)

[0133] [Example 21] In Example 21, the electrode material, the membrane electrode assembly, and the evaluation cell were produced, and the crystal structure of the electrode material was analyzed, in the same manner as in Example 1, except for the following item (1). (1) The starting materials for the electrode materials have been changed to the following materials: BaCO3 (0.200 mol, manufactured by Kanto Chemical Co., Ltd.) ZrO2 (0.025 mol, manufactured by Kanto Chemical Co., Ltd.) In2O3 (0.075 mol, manufactured by Kojundo Chemical Laboratory Co., Ltd.) Co3O4 (0.008 mol, manufactured by Kanto Chemical Co., Ltd.)

[0134] [Comparative Example 1] In Comparative Example 1, the electrode material, the membrane electrode assembly, and the evaluation cell were prepared, the crystal structure of the electrode material was analyzed, and the reaction resistance was measured using the evaluation cell in the same manner as in Example 1, except for the following items (1) and (2). (1) The starting materials for the electrode materials have been changed to the following materials: BaCO3 (0.200 mol, manufactured by Kanto Chemical Co., Ltd.) ZrO2 (0.160 mol, manufactured by Kanto Chemical Co., Ltd.) In2O3 (0.020 mol, manufactured by Kojundo Chemical Laboratory Co., Ltd.) (2) The firing temperature of the electrode material was 1400°C.

[0135] [Comparative Example 2] In Comparative Example 2, the electrode material, the membrane electrode assembly, and the evaluation cell were prepared, the crystal structure of the electrode material was analyzed, and the reaction resistance was measured using the evaluation cell in the same manner as in Example 1, except for the following items (1) and (2). (1) The starting materials for the electrode materials have been changed to the following materials: ·La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3-δ (Manufactured by Kusaka Rare Metals Laboratory Ltd.) (2) The electrode material was fired at 950°C.

[0136] (Experimental results and discussion) (X-ray diffraction profile and confirmation of synthesized compounds) 3 to 7 and Table 1, the X-ray diffraction profiles of the electrode materials according to Examples 1 to 21, Comparative Example 1, and Comparative Example 2 and the investigation of various synthesized compounds will be described.

[0137] Fig. 3 is a graph showing an X-ray diffraction profile of the electrode material according to Example 1. Fig. 4 is a graph showing an X-ray diffraction profile of the electrode material according to Example 2. The horizontal and vertical axes of Fig. 3 and Fig. 4 respectively indicate the diffraction angle (i.e., 2θ) and the X-ray intensity.

[0138] As shown in FIG. 3, the peak of the electrode material according to Example 1 was similar to the peak derived from BaZrO3 having a perovskite structure (database: ICDD, see the black downward triangles in FIG. 3). In other words, a shift of about +2 degrees at most was measured for the peak of the electrode material prepared by the method according to Example 1 compared to the peak derived from BaZrO3. These shifts are considered to be due to the solid solution of Co and In contained in the starting materials into the crystal of BaZrO3. Therefore, the electrode material according to Example 1 has a BaZr 0.375 In 0.375 Co 0.250 O 3-δ It was revealed that it is composed of a compound represented by, that is, it is composed of a single compound. In other words, it was revealed that the electrode material according to Example 1 is composed of a compound containing no impurities derived from the starting materials. As shown in FIG. 3, for the peaks derived from BaZrO3, peaks at 2θ = 21.1, 30.1, 37.1, 43.1, 53.5, 62.6, 71.0, and 79.0 (that is, among the peaks derived from BaZrO3, the eight peaks with relatively high intensity ratios) were used. Therefore, the electrode material according to Example 1 is composed of a single compound.

[0139] On the other hand, as shown in FIG. 4, in the peaks of the electrode material according to Example 2, a plurality of peaks not corresponding to the eight peaks derived from BaZrO3 were measured. For example, at 2θ = about 45.0, the electrode material according to Example 2 had a peak not seen in BaZrO3. The black circles shown in FIG. 4 are an example of a peak not corresponding to BaZrO3. These peaks are considered to be derived from the oxides derived from the starting materials and the starting materials of In2O3. Therefore, for Example 2 having a peak not corresponding to BaZrO3, BaZr 1-x-y In x Co y O 3-δ (0 < x < 1, 0 < y < 1, 0 < (x + y) < 1, 0 < δ < 1), it was determined that a mixture containing the oxides derived from the starting materials and the starting materials of In2O3 was synthesized.

[0140] Figure 5 is a graph showing the X-ray diffraction profiles of the electrode materials according to Examples 3 to 8. Figure 6 is a graph showing the X-ray diffraction profiles of the electrode materials according to Examples 9 to 14. The horizontal and vertical axes of Figures 5 and 6 respectively indicate the diffraction angle (i.e., 2θ) and the X-ray intensity.

[0141] The X-ray diffraction profiles of the electrode materials according to Examples 3 to 14 were confirmed by the same method as described above. The synthesized compounds were confirmed in the electrode materials according to Examples 3 to 14. The black circles shown in Figures 5 and 6 are examples of peaks that do not correspond to BaZrO3.

[0142] Table 1 shows whether the electrode materials according to the examples and comparative examples are composed of a single compound or a mixture containing multiple compounds. In Table 1, electrode materials determined to be composed of a single compound are represented by a white circle (i.e., ◯). In Table 1, electrode materials determined not to be composed of a single compound (i.e., composed of a mixture) are represented by an × symbol.

[0143] The electrode material may be a mixture of multiple compounds. An electrode containing such an electrode material functions as an electrode. However, an electrode made of an electrode material containing multiple compounds has a smaller reaction area than an electrode using an electrode material made of a single compound.

[0144] Therefore, as exemplified in Example 1, an electrode material containing a single compound is desirable as an electrode material.

[0145] (Evaluation of reaction resistance of cells according to Example 1 and Comparative Example 1) The results of evaluating the reaction resistance of the cells according to Example 1 and Comparative Example 1 will be described with reference to FIGS.

[0146] Figure 8 shows the Nyquist plot of the evaluation cell using the electrode material according to Example 1. Figure 9 shows the Nyquist plot of the evaluation cell using the electrode material according to Comparative Example 1. That is, Figures 8 and 9 respectively show the data of the Nyquist plot obtained by measuring the cells according to Example 1 and Comparative Example 1 by the alternating current impedance method.

[0147] As shown in Figure 8, the real number (referred to as R1 in Figure 8) from the high-frequency side intersection point (referred to as I1 in Figure 8) of the real axis (see the dashed line in Figure 8, that is, y = 0) and the arc drawn with the change of frequency to the low-frequency end (referred to as I2 in Figure 8) was calculated. The value obtained by halving this real number R1 is the reaction resistance (unit: Ωcm 2 )

[0148] Also, as shown in Figure 9, the Nyquist plot according to Comparative Example 1 does not have an intersection point between the real axis and the arc drawn with the change of the wave number. In this case, as shown in Figure 9, the real number (referred to as R2 in Figure 9) from the minimum point to the low-frequency end was calculated. The value obtained by halving this real number R2 was used as the reaction resistance.

[0149] The reaction resistance read from Figures 8 and 9 is clearly smaller for the cell according to Example 1 than for the cell according to Comparative Example 1. That is, the electrode of the cell according to Example 1 has excellent performance. As a reason, it is considered that Co contained in the electrode material according to Example 1 functioned as an electrode active site. However, as shown in Figure 9, the electrode material according to Comparative Example 1 has low function as an electrode.

[0150] Thus, it is considered that by adding Co to the compound represented by the chemical formula BaZr 1-x In x O 3-δ (where 0 < x < 1 and 0 < δ < 0.5) which has been used as a proton-conductive electrolyte material, an electrode material with excellent effects can be provided. Since Co is a transition metal, there is a possibility that δ becomes 0.5 or more when Co is added.

[0151] (Evaluation of reaction resistance of cells according to Example 1 and Comparative Example 2) 8, 10 and Table 1, the results of evaluating the reaction resistance of the cells according to Example 1 and Comparative Example 2 will be described.

[0152] Fig. 10 shows a Nyquist plot of an evaluation cell using the electrode material of Comparative Example 2. That is, Fig. 10 shows Nyquist plot data obtained by measuring the cell of Comparative Example 2 by an AC impedance method. The electrode material of Comparative Example 2 is known to have excellent electrode activity as a mixed conductor of oxide ions and electrons. The electrode material of Comparative Example 2 is a material that is often used for the air electrode of SOFC.

[0153] The Nyquist plot of the cell according to Comparative Example 2 showed a similar tendency to the Nyquist plot of the cell according to Example 1. That is, the resistance value tended to draw a semicircle as the AC signal applied changed from high frequency to low frequency.

[0154] The reaction resistance of the cell according to Example 1 is 0.05 Ωcm 2 On the other hand, the reaction resistance of the cell according to Comparative Example 2 was 0.49 Ω cm 2 The reaction resistance of the cell according to Example 1 was lower than that of the cell according to Comparative Example 2. Therefore, by using the cell according to Example 1 in various electrochemical devices, high electrode activity is expected. A fuel cell using the electrode material according to Example 1 is expected to have high output.

[0155] (Summary and Discussion) With reference to Table 1, the evaluation results of the cells of Examples 1 to 21, Comparative Example 1 and Comparative Example 2 will be described.

[0156] As shown in Table 1, the chemical formula BaZr 1-x-y In x Co y O 3-δ(Here, a compound represented by 0 < x < 1, 0 < y < 1, (x + y) < 1, and 0 < δ < 1) is synthesized as an electrode material composed of a single compound or as an electrode material composed of a mixture of the above compound and other compounds depending on the values of x and y. Chemical formula BaZr 1-x-y In x Co y O 3-δ (0 < x < 1, 0 < y < 1, (x + y) < 1, 0 < δ < 1) had a reaction resistance lower than that of the electrode material according to Comparative Example 2 depending on the composition. That is, for the electrode material of the present disclosure, there was found a possibility of achieving a lower reaction resistance than that of a conventional electrode material having excellent electrode activity as a mixed conductor of oxide ions and electrons. Specifically, the reaction resistance values of the electrode materials according to Example 1, Example 9, Example 10, Example 14, Example 16, and Example 17 were lower than the reaction resistance of the electrode material according to Comparative Example 2. It is considered that the electrode materials according to Example 1, Example 9, Example 10, Example 14, Example 16, and Example 17 are mixed conductors of protons and electrons. In the evaluation of the reaction resistance here, a material having proton conductivity, that is, BaZr 0.8 Yb 0.2 O 3-δ(where 0<δ<0.5) was used as the material of the electrolyte membrane. When a material without proton conductivity is used as an electrode for this electrolyte membrane as in Comparative Example 2, the interface where the electrons conducting the electrode, the protons conducting the electrolyte membrane, and the oxygen gas come into contact (i.e., the three-phase interface) becomes the region where the reaction proceeds. The oxygen gas at this time may be derived from air, for example, or a synthetic gas in which oxygen and gas such as nitrogen are mixed at any ratio may be used. On the other hand, when the electrode material has proton conductivity, the surface of the electrode particles (i.e., the two-phase interface) also becomes the region where the reaction proceeds. Generally, in cells of the same size, the area of ​​the three-phase interface is smaller than the area of ​​the two-phase interface. Therefore, by using the electrode material of the present disclosure in a cell equipped with an electrolyte membrane having proton conductivity as in Example 1, this cell has very excellent electrode performance. By using cells using the electrode materials according to Examples 1, 9, 10, 14, 16, and 17 in various electrochemical devices, high electrode activity is expected. Fuel cells using the electrode materials according to Examples 1, 9, 10, 14, 16 and 17 are expected to have high output. In addition, the reaction resistance values ​​of the electrode materials according to Examples 1, 9 and 14 were lower than 0.13. Therefore, by using cells using the electrode materials according to Examples 1, 9 and 14 in various electrochemical devices, higher electrode activity is expected. Fuel cells using the electrode materials according to Examples 1, 9 and 14 are expected to have higher output.

[0157] [Table 1]

[0158] [Example 22] (Preparation of electrode materials) The electrode materials were synthesized by the complex polymerization method. First, each solution was prepared. The electrode materials were synthesized using each solution.

[0159] (1) Preparation of each solution (a) Zr solution A solution of Zr was prepared using the following materials: ·ZrO(NO3)2·2H2O (240g, manufactured by Kanto Chemical Co., Ltd.)

[0160] The above materials were added to a polyethylene container containing 1800 mL of distilled water. The distilled water to which the above materials were added was then thoroughly stirred. In this way, a Zr solution was obtained. The concentration of Zr ions in this solution was calculated using inductively coupled plasma atomic emission spectroscopy (hereinafter, ICP-AES). Thermo Fisher Scientific's "iCAP7400 Duo" was used as the analytical device for ICP-AES. As a result of the analysis, the concentration of Zr in the Zr solution was 0.46 mol / L.

[0161] (b) Yb solution A solution of Yb was prepared using the following materials: ·Yb(NO3)3·5H2O (300g, manufactured by Kojundo Kagaku Kenkyusho Co., Ltd.) ·C6H8O7·H2O (300g, manufactured by Kanto Chemical Co., Ltd.)

[0162] The above materials were added to a polyethylene container containing 500 mL of distilled water. The distilled water to which the above materials had been added was then thoroughly stirred. In this way, a Yb solution was obtained. The concentration of Yb ions in this solution was calculated using ICP-AES in the same manner as in the calculation of the concentration of Zr ions in the Zr solution in (a) above. As a result, the concentration of Yb in the Yb solution was 0.87 mol / L. The concentration of citric acid (i.e., C6H8O7) in this solution was calculated to be 2.84 mol / L from the ratio of the amount of C6H8O7·H2O charged to the amount of distilled water charged.

[0163] (c) Co solution A solution of Co was prepared using the following materials: ·Co(NO3)2·6H2O (300g, manufactured by Kanto Chemical Co., Ltd.) ·C6H8O7·H2O (300g, manufactured by Kanto Chemical Co., Ltd.)

[0164] The above materials were added to a polyethylene container containing 500 mL of distilled water. The distilled water to which the above materials had been added was then thoroughly stirred. In this way, a Co solution was obtained. The concentration of Co ions in this solution was calculated using ICP-AES in the same manner as in the calculation of the concentration of Zr ions in the Zr solution in (a) above. As a result, the concentration of Co in the Co solution was 1.20 mol / L. The concentration of citric acid (i.e., C6H8O7) in this solution was calculated to be 2.84 mol / L from the ratio of the amount of C6H8O7·H2O charged to the amount of distilled water charged.

[0165] (d) Citric acid solution A solution of citric acid was prepared using the following ingredients: ·C6H8O7·H2O (1200g, manufactured by Kanto Chemical Co., Ltd.)

[0166] The above materials were added to a polyethylene container containing 2000 mL of distilled water. The distilled water to which the above materials were added was then thoroughly stirred. Thus, a solution of citric acid was obtained. The concentration of citric acid (i.e., C6H8O7) in this solution was calculated to be 2.84 mol / L based on the ratio of the amount of C6H8O7·H2O added to the amount of distilled water added.

[0167] (2) Synthesis of electrode materials Using each solution prepared by the above method, an electrode material according to Example 22 was synthesized. The following materials and solutions were used to synthesize the electrode material of Example 1. BaCO3 (0.05 mol, Kanto Chemical Co., Ltd.) ·C6H8O7·H2O (0.227 mol, manufactured by Kanto Chemical Co., Ltd.) ·Zr solution (54.3mL; Zr amount = 0.025mol) Yb solution (14.4 mL; Yb amount = 0.0125 mol, citric acid amount = 0.041 mol) Co solution (10.4 mL; Co amount = 0.0125 mol, citric acid amount = 0.030 mol) Citric acid solution (71.4 mL; amount of citric acid = 0.203 mol) Ethylene glycol (2 mol)

[0168] First, citric acid monohydrate (i.e., C6H8O7·H2O) was added to a 1L beaker. Next, 80 mL of distilled water was added to the 1L beaker and stirred with a stirrer. In this way, a colorless and transparent first aqueous solution was obtained. BaCO3 was added to the obtained colorless and transparent first aqueous solution. Then, BaCO3 was completely dissolved by further stirring with a stirrer. In this way, a colorless and transparent second aqueous solution was obtained. While continuing to stir the obtained colorless and transparent second aqueous solution, the above amounts of Zr solution, Yb solution, Co solution and citric acid solution were added to the obtained colorless and transparent second aqueous solution using a pipetter. Furthermore, ethylene glycol was also added to the obtained colorless and transparent second aqueous solution. In this way, a mixed solution was obtained.

[0169] The resulting mixed solution was stirred continuously with a stirrer. The resulting mixed solution was heated to about 90°C using a mantle heater. In this way, water was evaporated from the resulting mixed solution. The mixed solution was further heated to about 130°C, and ethylene glycol was evaporated and removed to accelerate polymerization and concentrate. Heating was stopped when the amount of solution decreased to 100 mL. In this way, a concentrated solution was obtained. The resulting concentrated solution was transferred to an alumina crucible and allowed to cool. Next, it was heated in a dryer at 120°C for 6 hours. In this way, ethylene glycol was removed from the concentrated solution. Then, the alumina crucible containing the concentrated solution from which ethylene glycol had been removed was calcined in air at 500°C for 3 hours. This removed the organic components. In this way, a solid was obtained. Then, the resulting solid was crushed in a mortar to obtain a calcined powder. Subsequently, the calcined powder was placed in an alumina crucible and fired in air at 1200°C for 2 hours. The resulting solid was crushed in a mortar. In this way, the electrode material was obtained. Table 2 shows the chemical formula of BaZr 1-x-y Yb x Co y O 3-δ The x and y values ​​in are shown.

[0170] (X-ray diffraction of electrode materials) The X-ray diffraction device "Smartlab" (manufactured by Rigaku) ​​was used to analyze the crystal structure of the obtained electrode material. Specifically, CuKα radiation was used as the X-ray source, and the obtained electrode material was irradiated with X-rays using the parallel beam method. Using the known BaZrO3 peak (database: JCPDS 00-006-0399) as a reference, it was confirmed that an oxide with the desired composition had been synthesized.

[0171] (Fabrication of membrane electrode assembly) Next, a method for producing the membrane electrode assembly will be described.

[0172] First, BaZr 0.8 Yb 0.2 O 2.9 The electrolyte membrane was fabricated using the powder molding die (diameter 20 mm). 0.8 Yb 0.2 O 2.9 Next, about 10 g of the electrolyte material BaZr 0.8 Yb 0.2 O 2.9 The pellets were pressed into a cylindrical shape to obtain pellets. The pellets were placed in a bag and packed. The bag containing the pellets was then pressurized at 200 MPa for 3 minutes by cold isostatic pressing (i.e., "CIP"). In this way, a molded body was obtained. The molded body obtained was fired at 1750°C for 24 hours in an air atmosphere to obtain a sintered body. The sintered body obtained was polished using a wrapping film (manufactured by 3M) having a grain size of 15 microns. After polishing, the sintered body obtained had a thickness of about 500 μm. In this way, an electrolyte membrane was produced. The electrolyte membrane had two main surfaces (i.e., a first main surface and a second main surface). In addition, the electrolyte material BaZr 0.8 Yb 0.2 O 2.9 The chemical formula is BaZr 1-x1 M1 x1 O 3-δ This corresponds to a compound in which M1 is Yb, x1=0.2, and δ=0.1.

[0173] Next, the first electrode was prepared. The electrode material prepared by the above-mentioned method was pulverized by a planetary ball mill (manufactured by Fritsch) and used for the preparation of the first electrode. The electrode material was pulverized using zirconia balls (φ2 mm). Butyl acetate was used as the solvent. The planetary ball mill was used under the conditions of 350 rpm for 120 minutes. Then, the powder of the electrode material was filtered out from the zirconia balls and the butyl acetate solvent, and dried. In this way, the electrode material after pulverization was obtained. The particle size distribution of the obtained electrode material after pulverization was measured by a particle size distribution measuring device (product name: MT3300EXII, manufactured by Microtrac). The median diameter D50 value of the electrode material after pulverization was approximately 0.3 μm. The median diameter D50 means the particle size when the cumulative volume in the volume-based particle size distribution is equal to 50%.

[0174] Next, in order to apply the pulverized electrode material in the form of a film, the electrode material was made into a paste by the following method.

[0175] The following materials were prepared as starting materials for the paste: 10g of pulverized electrode material EC vehicle (manufactured by Nisshin Chemical Co., Ltd.) 6.7g

[0176] The electrode material and the EC vehicle were added to a plastic container. The mixture was stirred at 1000 rpm for 5 minutes using a planetary centrifugal mixer. In this way, a paste precursor was obtained. The paste precursor obtained was dispersed using a three-roll mill (product name: BR-100VIII, manufactured by Imex). In this way, an electrode dispersion liquid was obtained.

[0177] The obtained electrode dispersion was printed by screen printing at the center of the first main surface of the electrolyte membrane prepared by the above method. The first electrode thus prepared was circular and had a diameter of 15 mm. In this manner, a membrane electrode assembly was prepared.

[0178] (Preparation of evaluation cells) Next, a method for preparing an evaluation cell for evaluating electrode activity will be described.

[0179] First, a membrane electrode assembly for evaluation was produced using the membrane electrode assembly produced by the above-mentioned method.

[0180] The electrode dispersion liquid was also printed on the second main surface of the electrolyte membrane constituting the membrane electrode assembly. Next, the membrane electrode assembly on which the electrode dispersion liquid was printed was baked in an air atmosphere at 1100°C (hereinafter referred to as the "electrode baking temperature") for 2 hours. In this way, a membrane electrode assembly for evaluation was obtained.

[0181] Next, an evaluation cell was fabricated using the obtained membrane electrode assembly for evaluation. The following method was used to evaluate the electrode activity using the fabricated membrane electrode assembly for evaluation. The following items were prepared to fabricate the evaluation cell. Membrane electrode assembly for evaluation Silver ink (manufactured by Toyo Corporation)

[0182] Using a screen printing method, silver ink was printed on the electrodes on both sides of the membrane electrode assembly for evaluation. In this way, a precursor of the evaluation cell was obtained. The printed silver ink had a diameter of 15 mm. The obtained precursor of the evaluation cell was then fired in an air atmosphere at 800°C for 1 hour. In this way, the evaluation cell was produced.

[0183] (Measurement of reaction resistance using an evaluation cell) The reaction resistance of the evaluation cell was measured.

[0184] Air (flow rate: 100 mL / min) humidified to a dew point temperature of 20°C was passed through the evaluation cell, and the reaction resistance of the evaluation cell was measured based on the AC impedance method performed at a temperature of 600°C.

[0185] Specifically, an AC signal was applied to the cell with an amplitude of 10 mV in the range of 1 MHz to 0.01 Hz using ModuLab XM ECS (manufactured by Solartron Analytical). For an arc drawn in the frequency range of approximately 100 kHz to 0.01 Hz in the Nyquist plot, the real number was calculated from the intersection of the arc and the real axis on the high frequency side to the low frequency end. In a fuel cell, the semicircular waveform obtained as the reaction resistance in the AC impedance method is usually observed separately for the positive and negative electrodes. However, in this measurement, an evaluation cell made of the same material on both sides is used. Therefore, in the results obtained in this measurement, the current response of the air electrode is displayed overlapping. Therefore, in order to consider the electrode activity per side, the real number was halved, and this halved real number was taken as the reaction resistance. The reaction resistance is the energy loss required for electron transfer in the electrochemical reaction at the electrode. The calculated resistance is considered to have a correlation with the activity of the electrode. Therefore, the electrode activity was judged based on the magnitude of the calculated resistance.

[0186] For specific methods of evaluating reaction resistance, see below. (i) When an intersection point between the arc and the real axis on the high frequency side (e.g., I3 in Figure 17) is observed in the Nyquist plot of a circular arc drawn in the frequency range of approximately 100 kHz to 0.01 Hz, The real number (e.g., R4 shown in FIG. 17) from the intersection point of the arc and the real axis on the high frequency side to the low frequency end (e.g., I4 shown in FIG. 17) was obtained. Then, the real number was taken as the reaction resistance. (ii) In the Nyquist plot, for a circular arc drawn in the frequency range of approximately 100 kHz to 0.01 Hz, no intersection point is observed between the circular arc and the real axis on the high frequency side. The real number from the minimum point of the arc to the low frequency end was calculated, and this real number was taken as the reaction resistance.

[0187] [Example 23] In Example 23, the electrode material, the membrane electrode assembly, and the evaluation cell were prepared, and the crystal structure of the electrode material was analyzed, in the same manner as in Example 22, except for the following items (1) and (2). (1) The starting materials for the electrode materials were changed to the following materials and solutions. BaCO3 (0.05 mol, Kanto Chemical Co., Ltd.) ·C6H8O7·H2O (0.227 mol, manufactured by Kanto Chemical Co., Ltd.) ·Zr solution (13.6mL; Zr amount = 0.0063mol) Yb solution (14.4 mL; Yb amount = 0.0125 mol, citric acid amount = 0.041 mol) Co solution (26.0 mL; Co amount = 0.0313 mol, citric acid amount = 0.074 mol) Citric acid solution (55.8 mL; amount of citric acid = 0.158 mol) Ethylene glycol (2 mol) (2) The electrode materials were fired at two temperatures: 1100°C and 1200°C.

[0188] [Example 24] In Example 24, the electrode material, the membrane electrode assembly, and the evaluation cell were prepared, the crystal structure of the electrode material was analyzed, and the reaction resistance was measured using the evaluation cell in the same manner as in Example 22, except for the following item (1). (1) The starting materials for the electrode materials were changed to the following materials and solutions. BaCO3 (0.05 mol, Kanto Chemical Co., Ltd.) ·C6H8O7·H2O (0.227 mol, manufactured by Kanto Chemical Co., Ltd.) ·Zr solution (81.5mL; Zr amount = 0.0375mol) Yb solution (7.2 mL; Yb amount = 0.0063 mol, citric acid amount = 0.02 mol) Co solution (5.2 mL; Co amount = 0.0063 mol, citric acid amount = 0.015 mol) Citric acid solution (83.8 mL; amount of citric acid = 0.238 mol) Ethylene glycol (2 mol)

[0189] [Example 25] In Example 25, the electrode material, the membrane electrode assembly, and the evaluation cell were prepared, the crystal structure of the electrode material was analyzed, and the reaction resistance was measured using the evaluation cell in the same manner as in Example 22, except for the following item (1). (1) The starting materials for the electrode materials were changed to the following materials and solutions. BaCO3 (0.05 mol, Kanto Chemical Co., Ltd.) ·C6H8O7·H2O (0.227 mol, manufactured by Kanto Chemical Co., Ltd.) ·Zr solution (67.9mL; Zr amount = 0.0313mol) Yb solution (7.2 mL; Yb amount = 0.0063 mol, citric acid amount = 0.02 mol) Co solution (10.4 mL; Co amount = 0.0125 mol, citric acid amount = 0.030 mol) Citric acid solution (78.6 mL; amount of citric acid = 0.223 mol) Ethylene glycol (2 mol)

[0190] [Example 26] In Example 26, the electrode material, the membrane electrode assembly, and the evaluation cell were prepared, the crystal structure of the electrode material was analyzed, and the reaction resistance was measured using the evaluation cell in the same manner as in Example 22, except for the following items (1) and (2). (1) The starting materials for the electrode materials were changed to the following materials and solutions. BaCO3 (0.05 mol, Kanto Chemical Co., Ltd.) ·C6H8O7·H2O (0.227 mol, manufactured by Kanto Chemical Co., Ltd.) ·Zr solution (54.4mL; Zr amount = 0.025mol) Yb solution (7.2 mL; Yb amount = 0.0063 mol, citric acid amount = 0.02 mol) Co solution (15.6 mL; Co amount = 0.0188 mol, citric acid amount = 0.044 mol) Citric acid solution (73.4 mL; amount of citric acid = 0.208 mol) Ethylene glycol (2 mol) (2) The electrode material was fired at 1100°C.

[0191] [Example 27] In Example 27, the electrode material, the membrane electrode assembly, and the evaluation cell were prepared, the crystal structure of the electrode material was analyzed, and the reaction resistance was measured using the evaluation cell in the same manner as in Example 22, except for the following items (1) and (2). (1) The starting materials for the electrode materials were changed to the following materials and solutions. BaCO3 (0.05 mol, Kanto Chemical Co., Ltd.) ·C6H8O7·H2O (0.227 mol, manufactured by Kanto Chemical Co., Ltd.) ·Zr solution (40.8mL; Zr amount = 0.0188mol) Yb solution (7.2 mL; Yb amount = 0.0063 mol, citric acid amount = 0.02 mol) Co solution (20.8 mL; Co amount = 0.025 mol, citric acid amount = 0.059 mol) Citric acid solution (68.1 mL; amount of citric acid = 0.194 mol) Ethylene glycol (2 mol) (2) The electrode material was fired at 1100°C.

[0192] [Example 28] In Example 28, the electrode material, the membrane electrode assembly, and the evaluation cell were prepared, the crystal structure of the electrode material was analyzed, and the reaction resistance was measured using the evaluation cell in the same manner as in Example 22, except for the following items (1) and (2). (1) The starting materials for the electrode materials were changed to the following materials and solutions. BaCO3 (0.05 mol, Kanto Chemical Co., Ltd.) ·C6H8O7·H2O (0.227 mol, manufactured by Kanto Chemical Co., Ltd.) ·Zr solution (27.2mL; Zr amount = 0.0125mol) Yb solution (7.2 mL; Yb amount = 0.0063 mol, citric acid amount = 0.02 mol) Co solution (26.0 mL; Co amount = 0.0313 mol, citric acid amount = 0.074 mol) Citric acid solution (62.9 mL; amount of citric acid = 0.179 mol) Ethylene glycol (2 mol) (2) The electrode material was fired at 1100°C.

[0193] [Example 29] In Example 29, the electrode material, the membrane electrode assembly, and the evaluation cell were prepared, the crystal structure of the electrode material was analyzed, and the reaction resistance was measured using the evaluation cell in the same manner as in Example 22, except for the following item (1). (1) The starting materials for the electrode materials were changed to the following materials and solutions. BaCO3 (0.05 mol, Kanto Chemical Co., Ltd.) ·C6H8O7·H2O (0.227 mol, manufactured by Kanto Chemical Co., Ltd.) ·Zr solution (13.6mL; Zr amount = 0.0063mol) Yb solution (7.2 mL; Yb amount = 0.0063 mol, citric acid amount = 0.02 mol) Co solution (31.3 mL; Co amount = 0.0375 mol, citric acid amount = 0.089 mol) Citric acid solution (57.7 mL; amount of citric acid = 0.164 mol) Ethylene glycol (2 mol)

[0194] [Example 30] In Example 30, the electrode material, the membrane electrode assembly, and the evaluation cell were prepared, the crystal structure of the electrode material was analyzed, and the reaction resistance was measured using the evaluation cell in the same manner as in Example 22, except for the following item (1). (1) The starting materials for the electrode materials were changed to the following materials and solutions. BaCO3 (0.05 mol, Kanto Chemical Co., Ltd.) ·C6H8O7·H2O (0.227 mol, manufactured by Kanto Chemical Co., Ltd.) ·Zr solution (67.9mL; Zr amount = 0.0313mol) Yb solution (14.4 mL; Yb amount = 0.0125 mol, citric acid amount = 0.041 mol) Co solution (5.2 mL; Co amount = 0.0063 mol, citric acid amount = 0.015 mol) Citric acid solution (76.6 mL; amount of citric acid = 0.218 mol) Ethylene glycol (2 mol)

[0195] [Example 31] In Example 31, the electrode material, the membrane electrode assembly, and the evaluation cell were prepared, the crystal structure of the electrode material was analyzed, and the reaction resistance was measured using the evaluation cell in the same manner as in Example 22, except for the following items (1) and (2). (1) The starting materials for the electrode materials were changed to the following materials and solutions. BaCO3 (0.05 mol, Kanto Chemical Co., Ltd.) ·C6H8O7·H2O (0.227 mol, manufactured by Kanto Chemical Co., Ltd.) ·Zr solution (40.8mL; Zr amount = 0.0188mol) Yb solution (14.4 mL; Yb amount = 0.0125 mol, citric acid amount = 0.041 mol) Co solution (15.6 mL; Co amount = 0.0188 mol, citric acid amount = 0.044 mol) Citric acid solution (66.2 mL; amount of citric acid = 0.188 mol) Ethylene glycol (2 mol) (2) The electrode material was fired at 1100°C.

[0196] [Example 32] In Example 32, the electrode material, the membrane electrode assembly, and the evaluation cell were prepared, the crystal structure of the electrode material was analyzed, and the reaction resistance was measured using the evaluation cell in the same manner as in Example 22, except for the following items (1) and (2). (1) The starting materials for the electrode materials were changed to the following materials and solutions. BaCO3 (0.05 mol, Kanto Chemical Co., Ltd.) ·C6H8O7·H2O (0.227 mol, manufactured by Kanto Chemical Co., Ltd.) ·Zr solution (27.2mL; Zr amount = 0.0125mol) Yb solution (14.4 mL; Yb amount = 0.0125 mol, citric acid amount = 0.041 mol) Co solution (20.8 mL; Co amount = 0.025 mol, citric acid amount = 0.059 mol) Citric acid solution (61.0 mL; amount of citric acid = 0.173 mol) Ethylene glycol (2 mol) (2) The electrode material was fired at 1100°C.

[0197] [Example 33] In Example 33, the electrode material, the membrane electrode assembly, and the evaluation cell were prepared, the crystal structure of the electrode material was analyzed, and the reaction resistance was measured using the evaluation cell in the same manner as in Example 22, except for the following item (1). (1) The starting materials for the electrode materials were changed to the following materials and solutions. BaCO3 (0.05 mol, Kanto Chemical Co., Ltd.) ·C6H8O7·H2O (0.227 mol, manufactured by Kanto Chemical Co., Ltd.) ·Zr solution (13.6mL; Zr amount = 0.0063mol) Yb solution (14.4 mL; Yb amount = 0.0125 mol, citric acid amount = 0.041 mol) Co solution (26.0 mL; Co amount = 0.0313 mol, citric acid amount = 0.074 mol) Citric acid solution (55.8 mL; amount of citric acid = 0.158 mol) Ethylene glycol (2 mol)

[0198] [Example 34] In Example 34, the electrode material, the membrane electrode assembly, and the evaluation cell were prepared, the crystal structure of the electrode material was analyzed, and the reaction resistance was measured using the evaluation cell in the same manner as in Example 22, except for the following item (1). (1) The starting materials for the electrode materials were changed to the following materials and solutions. BaCO3 (0.05 mol, Kanto Chemical Co., Ltd.) ·C6H8O7·H2O (0.227 mol, manufactured by Kanto Chemical Co., Ltd.) ·Zr solution (54.4mL; Zr amount = 0.025mol) Yb solution (21.6 mL; Yb amount = 0.0188 mol, citric acid amount = 0.061 mol) Co solution (5.2 mL; Co amount = 0.0063 mol, citric acid amount = 0.015 mol) Citric acid solution (69.4 mL; amount of citric acid = 0.197 mol) Ethylene glycol (2 mol)

[0199] [Example 35] In Example 35, the electrode material, the membrane electrode assembly, and the evaluation cell were prepared, the crystal structure of the electrode material was analyzed, and the reaction resistance was measured using the evaluation cell in the same manner as in Example 22, except for the following item (1). (1) The starting materials for the electrode materials were changed to the following materials and solutions. BaCO3 (0.05 mol, Kanto Chemical Co., Ltd.) ·C6H8O7·H2O (0.227 mol, manufactured by Kanto Chemical Co., Ltd.) ·Zr solution (40.8mL; Zr amount = 0.0188mol) Yb solution (21.6 mL; Yb amount = 0.0188 mol, citric acid amount = 0.061 mol) Co solution (10.4 mL; Co amount = 0.0125 mol, citric acid amount = 0.030 mol) Citric acid solution (64.2 mL; amount of citric acid = 0.182 mol) Ethylene glycol (2 mol)

[0200] [Example 36] In Example 36, the electrode material, the membrane electrode assembly, and the evaluation cell were prepared, the crystal structure of the electrode material was analyzed, and the reaction resistance was measured using the evaluation cell in the same manner as in Example 22, except for the following item (1). (1) The starting materials for the electrode materials were changed to the following materials and solutions. BaCO3 (0.05 mol, Kanto Chemical Co., Ltd.) ·C6H8O7·H2O (0.227 mol, manufactured by Kanto Chemical Co., Ltd.) ·Zr solution (27.2mL; Zr amount = 0.0125mol) Yb solution (21.6 mL; Yb amount = 0.0188 mol, citric acid amount = 0.061 mol) Co solution (15.6 mL; Co amount = 0.0188 mol, citric acid amount = 0.044 mol) Citric acid solution (59.0 mL; amount of citric acid = 0.168 mol) Ethylene glycol (2 mol)

[0201] [Example 37] In Example 37, the electrode material, the membrane electrode assembly, and the evaluation cell were prepared, the crystal structure of the electrode material was analyzed, and the reaction resistance was measured using the evaluation cell in the same manner as in Example 22, except for the following item (1). (1) The starting materials for the electrode materials were changed to the following materials and solutions. BaCO3 (0.05 mol, Kanto Chemical Co., Ltd.) ·C6H8O7·H2O (0.227 mol, manufactured by Kanto Chemical Co., Ltd.) ·Zr solution (13.6mL; Zr amount = 0.0063mol) Yb solution (21.6 mL; Yb amount = 0.0188 mol, citric acid amount = 0.061 mol) Co solution (20.8 mL; Co amount = 0.025 mol, citric acid amount = 0.059 mol) Citric acid solution (53.8 mL; amount of citric acid = 0.153 mol) Ethylene glycol (2 mol)

[0202] [Example 38] In Example 38, the electrode material, the membrane electrode assembly, and the evaluation cell were prepared, the crystal structure of the electrode material was analyzed, and the reaction resistance was measured using the evaluation cell in the same manner as in Example 22, except for the following item (1). (1) The starting materials for the electrode materials were changed to the following materials and solutions. BaCO3 (0.05 mol, Kanto Chemical Co., Ltd.) ·C6H8O7·H2O (0.227 mol, manufactured by Kanto Chemical Co., Ltd.) ·Zr solution (40.8mL; Zr amount = 0.0188mol) Yb solution (28.7 mL; Yb amount = 0.025 mol, citric acid amount = 0.082 mol) Co solution (5.2 mL; Co amount = 0.0063 mol, citric acid amount = 0.015 mol) Citric acid solution (62.2 mL; amount of citric acid = 0.177 mol) Ethylene glycol (2 mol)

[0203] [Example 39] In Example 39, the electrode material, the membrane electrode assembly, and the evaluation cell were prepared, the crystal structure of the electrode material was analyzed, and the reaction resistance was measured using the evaluation cell in the same manner as in Example 22, except for the following item (1). (1) The starting materials for the electrode materials were changed to the following materials and solutions. BaCO3 (0.05 mol, Kanto Chemical Co., Ltd.) ·C6H8O7·H2O (0.227 mol, manufactured by Kanto Chemical Co., Ltd.) ·Zr solution (27.2mL; Zr amount = 0.0125mol) Yb solution (28.7 mL; Yb amount = 0.025 mol, citric acid amount = 0.082 mol) Co solution (10.4 mL; Co amount = 0.0125 mol, citric acid amount = 0.030 mol) Citric acid solution (57.0 mL; amount of citric acid = 0.162 mol) Ethylene glycol (2 mol)

[0204] [Example 40] In Example 40, the electrode material, the membrane electrode assembly, and the evaluation cell were prepared, the crystal structure of the electrode material was analyzed, and the reaction resistance was measured using the evaluation cell in the same manner as in Example 22, except for the following item (1). (1) The starting materials for the electrode materials were changed to the following materials and solutions. BaCO3 (0.05 mol, Kanto Chemical Co., Ltd.) ·C6H8O7·H2O (0.227 mol, manufactured by Kanto Chemical Co., Ltd.) ·Zr solution (13.6mL; Zr amount = 0.0063mol) Yb solution (28.7 mL; Yb amount = 0.025 mol, citric acid amount = 0.082 mol) Co solution (15.6 mL; Co amount = 0.0188 mol, citric acid amount = 0.044 mol) Citric acid solution (51.8 mL; amount of citric acid = 0.147 mol) Ethylene glycol (2 mol)

[0205] [Example 41] In Example 41, the electrode material, the membrane electrode assembly, and the evaluation cell were prepared, the crystal structure of the electrode material was analyzed, and the reaction resistance was measured using the evaluation cell in the same manner as in Example 22, except for the following item (1). (1) The starting materials for the electrode materials were changed to the following materials and solutions. BaCO3 (0.05 mol, Kanto Chemical Co., Ltd.) ·C6H8O7·H2O (0.227 mol, manufactured by Kanto Chemical Co., Ltd.) ·Zr solution (13.6mL; Zr amount = 0.0063mol) Yb solution (35.9 mL; Yb amount = 0.0313 mol, citric acid amount = 0.102 mol) Co solution (10.4 mL; Co amount = 0.0125 mol, citric acid amount = 0.030 mol) Citric acid solution (49.8 mL; amount of citric acid = 0.142 mol) Ethylene glycol (2 mol)

[0206] [Example 42] In Example 42, the electrode material, the membrane electrode assembly, and the evaluation cell were prepared, and the crystal structure of the electrode material was analyzed, in the same manner as in Example 22, except for the following item (1). (1) The starting materials for the electrode materials were changed to the following materials and solutions. BaCO3 (0.05 mol, Kanto Chemical Co., Ltd.) ·C6H8O7·H2O (0.227 mol, manufactured by Kanto Chemical Co., Ltd.) ·Zr solution (13.6mL; Zr amount = 0.0063mol) Yb solution (43.1 mL; Yb amount = 0.0375 mol, citric acid amount = 0.122 mol) Co solution (5.2 mL; Co amount = 0.0063 mol, citric acid amount = 0.015 mol) Citric acid solution (47.9 mL; amount of citric acid = 0.136 mol) Ethylene glycol (2 mol)

[0207] [Example 43] In Example 43, the electrode material, the membrane electrode assembly, and the evaluation cell were prepared, and the crystal structure of the electrode material was analyzed, in the same manner as in Example 22, except for the following items (1) and (2). (1) The starting materials for the electrode materials were changed to the following materials and solutions. BaCO3 (0.05 mol, Kanto Chemical Co., Ltd.) ·C6H8O7·H2O (0.227 mol, manufactured by Kanto Chemical Co., Ltd.) ·Zr solution (87.0mL; Zr amount = 0.040mol) Yb solution (4.3 mL; Yb amount = 0.0038 mol, citric acid amount = 0.012 mol) Co solution (5.2 mL; Co amount = 0.0063 mol, citric acid amount = 0.015 mol) Citric acid solution (86.6 mL; amount of citric acid = 0.246 mol) Ethylene glycol (2 mol) (2) The electrode material was fired at 1100°C.

[0208] [Example 44] In Example 44, the electrode material, the membrane electrode assembly, and the evaluation cell were prepared, and the crystal structure of the electrode material was analyzed, in the same manner as in Example 22, except for the following items (1) and (2). (1) The starting materials for the electrode materials were changed to the following materials and solutions. BaCO3 (0.05 mol, Kanto Chemical Co., Ltd.) ·C6H8O7·H2O (0.227 mol, manufactured by Kanto Chemical Co., Ltd.) ·Zr solution (73.4mL; Zr amount = 0.0338mol) Yb solution (4.3 mL; Yb amount = 0.0038 mol, citric acid amount = 0.012 mol) Co solution (10.4 mL; Co amount = 0.0125 mol, citric acid amount = 0.030 mol) Citric acid solution (81.4 mL; amount of citric acid = 0.231 mol) Ethylene glycol (2 mol) (2) The electrode material was fired at 1100°C.

[0209] [Example 45] In Example 45, the electrode material, the membrane electrode assembly, and the evaluation cell were prepared, and the crystal structure of the electrode material was analyzed, in the same manner as in Example 22, except for the following items (1) and (2). (1) The starting materials for the electrode materials were changed to the following materials and solutions. BaCO3 (0.05 mol, Kanto Chemical Co., Ltd.) ·C6H8O7·H2O (0.227 mol, manufactured by Kanto Chemical Co., Ltd.) ·Zr solution (59.8mL; Zr amount = 0.0275mol) Yb solution (4.3 mL; Yb amount = 0.0038 mol, citric acid amount = 0.012 mol) Co solution (15.6 mL; Co amount = 0.0188 mol, citric acid amount = 0.044 mol) Citric acid solution (76.2 mL; amount of citric acid = 0.217 mol) Ethylene glycol (2 mol) (2) The electrode material was fired at 1100°C.

[0210] [Example 46] In Example 46, the electrode material, the membrane electrode assembly, and the evaluation cell were prepared, and the crystal structure of the electrode material was analyzed, in the same manner as in Example 22, except for the following items (1) and (2). (1) The starting materials for the electrode materials were changed to the following materials and solutions. BaCO3 (0.05 mol, Kanto Chemical Co., Ltd.) ·C6H8O7·H2O (0.227 mol, manufactured by Kanto Chemical Co., Ltd.) ·Zr solution (46.2mL; Zr amount = 0.0213mol) Yb solution (4.3 mL; Yb amount = 0.0038 mol, citric acid amount = 0.012 mol) Co solution (20.8 mL; Co amount = 0.025 mol, citric acid amount = 0.059 mol) Citric acid solution (71.0 mL; amount of citric acid = 0.202 mol) Ethylene glycol (2 mol) (2) The electrode material was fired at 1100°C.

[0211] [Example 47] In Example 47, the electrode material, the membrane electrode assembly, and the evaluation cell were prepared, and the crystal structure of the electrode material was analyzed, in the same manner as in Example 22, except for the following items (1) and (2). (1) The starting materials for the electrode materials were changed to the following materials and solutions. BaCO3 (0.05 mol, Kanto Chemical Co., Ltd.) ·C6H8O7·H2O (0.227 mol, manufactured by Kanto Chemical Co., Ltd.) ·Zr solution (32.6mL; Zr amount = 0.015mol) Yb solution (4.3 mL; Yb amount = 0.0038 mol, citric acid amount = 0.012 mol) Co solution (26.0 mL; Co amount = 0.0313 mol, citric acid amount = 0.074 mol) Citric acid solution (65.81 mL; amount of citric acid = 0.187 mol) Ethylene glycol (2 mol) (2) The electrode material was fired at 1100°C.

[0212] [Example 48] In Example 48, the electrode material, the membrane electrode assembly, and the evaluation cell were prepared, and the crystal structure of the electrode material was analyzed, in the same manner as in Example 22, except for the following items (1) and (2). (1) The starting materials for the electrode materials were changed to the following materials and solutions. BaCO3 (0.05 mol, Kanto Chemical Co., Ltd.) ·C6H8O7·H2O (0.227 mol, manufactured by Kanto Chemical Co., Ltd.) ·Zr solution (19.0mL; Zr amount = 0.0088mol) Yb solution (4.3 mL; Yb amount = 0.0038 mol, citric acid amount = 0.012 mol) Co solution (31.3 mL; Co amount = 0.0375 mol, citric acid amount = 0.089 mol) Citric acid solution (60.6 mL; amount of citric acid = 0.172 mol) Ethylene glycol (2 mol) (2) The electrode material was fired at 1100°C.

[0213] [Comparative Example 3] In Comparative Example 3, the electrode material, the membrane electrode assembly, and the evaluation cell were prepared, the crystal structure of the electrode material was analyzed, and the reaction resistance was measured using the evaluation cell in the same manner as in Example 22, except for the following items (1) and (2). (1) The starting materials for the electrode materials have been changed to the following materials: BaCO3 (0.200 mol, manufactured by Kanto Chemical Co., Ltd.) ZrO2 (0.160 mol, manufactured by Kanto Chemical Co., Ltd.) Yb2O3 (0.020 mol, manufactured by Kojundo Chemical Laboratory Co., Ltd.) (2) The synthesis procedure for the electrode material was changed to the following: The starting materials and 50 mL of distilled water were added to a 250 mL container. Next, the container was stirred at 200 rpm for 10 minutes using a planetary ball mill (manufactured by Fritsch). This stirring process was repeated twice. In this way, a mixed liquid was obtained. The mixed liquid obtained was dried at 120°C for 6 hours in a dryer (MOV-212F, manufactured by Panasonic). Then, moisture was removed from the mixed liquid. In this way, a solid was obtained. The obtained solid was crushed in a mortar, and the obtained powder was transferred to an alumina crucible (manufactured by Nikkato Corporation). Then, the alumina crucible was fired at a temperature of 1400°C in an air atmosphere for 2 hours. In this way, an electrode material was obtained. Table 2 shows the chemical formula BaZr 1-x-y Yb x Co y O 3-δ The x and y values ​​in are summarized.

[0214] (Experimental results and discussion) (X-ray diffraction profile and confirmation of synthesized compounds) 11 to 15 and Table 2 are used to explain the X-ray diffraction profiles of the electrode materials according to Examples 22 to 48 and Comparative Examples 1 to 3, and the investigation of various synthesized compounds.

[0215] Fig. 11 is a graph showing an X-ray diffraction profile of an electrode material according to Example 22. Fig. 12 is a graph showing an X-ray diffraction profile of an electrode material according to Example 23. The horizontal and vertical axes of Fig. 11 and Fig. 12 respectively indicate the diffraction angle (i.e., 2θ) and the X-ray intensity.

[0216] As shown in FIG. 11, the peak of the electrode material according to Example 22 almost coincides with the peak derived from BaZrO3 having a perovskite structure (database: JCPDS 00-006-0399, see the black downward triangle in FIG. 11). A slight peak shift to the high angle side is observed, but this is thought to be due to the Co and Yb contained in the starting material being dissolved in the BaZrO3 crystal. Therefore, the electrode material according to Example 1 is BaZr0.500 In 0.250 Co 0.250 O 3-δ It was revealed that it is composed of a compound represented by, that is, it is composed of a single compound. In other words, it was revealed that it is composed of a compound containing no impurities derived from the starting material.

[0217] On the other hand, as shown in FIG. 12, at the peak of the electrode material according to Example 23, a plurality of peaks not corresponding to the peak derived from BaZrO3 were detected. For example, at 2θ = about 24°, the electrode material according to Example 2 had a peak not seen in BaZrO3. The black circles in FIG. 12 are an example of a peak not corresponding to BaZrO3. These peaks are considered to be derived from the starting material. Therefore, Example 23 having a peak not corresponding to BaZrO3 is BaZr 1-x-y Yb x Co y O 3-δ (0 < x < 1, 0 < y < 1, 0 < (x + y) < 1, 0 < δ < 1) and a mixture containing a compound derived from the starting material was judged to be synthesized.

[0218] FIG. 13 is a graph showing the X-ray diffraction profiles of the electrode materials according to Examples 24 to 29. FIG. 14 is a graph showing the X-ray diffraction profiles of the electrode materials according to Examples 30 to 35. FIG. 15 is a graph showing the X-ray diffraction profiles of the electrode materials according to Examples 36 to 42. FIG. 16 is a graph showing the X-ray diffraction profiles of the electrode materials according to Examples 43 to 48. The horizontal and vertical axes in FIGS. 13 to 16 indicate the diffraction angle (i.e., 2θ) and the X-ray intensity, respectively.

[0219] The X-ray diffraction profiles of the electrode materials according to Examples 24 to 48 were confirmed in the same manner as the above method. In the electrode materials according to Examples 24 to 48, the synthesized compound was confirmed. The black circles shown in FIGS. 15 and 16 are an example of a peak not corresponding to BaZrO3.

[0220] Table 2 shows whether the electrode materials according to the examples and comparative examples are composed of a single compound or a mixture containing multiple compounds. In Table 2, electrode materials determined to be composed of a single compound are represented by a white circle (i.e., ◯). In Table 2, electrode materials determined not to be composed of a single compound (i.e., composed of a mixture) are represented by a × symbol. Comparative Examples 1 and 2 are also listed in Table 2.

[0221] The electrode material may be a mixture of multiple compounds. An electrode containing such an electrode material functions as an electrode. However, an electrode made of an electrode material containing multiple compounds has a smaller reaction area than an electrode using an electrode material made of a single compound.

[0222] Therefore, as exemplified in Example 22, an electrode material containing a single compound is desirable as an electrode material.

[0223] (Evaluation of reaction resistance of cells according to Example 22, Comparative Example 3, and Comparative Example 1) The results of evaluating the reaction resistance of the cells according to Example 1, Comparative Example 3, and Comparative Example 1 will be described with reference to FIGS. 17, 18, and 9. FIG.

[0224] Fig. 17 shows a Nyquist plot of an evaluation cell using the electrode material according to Example 22. Fig. 18 shows a Nyquist plot of an evaluation cell using the electrode material according to Comparative Example 3. Fig. 9 shows a Nyquist plot of an evaluation cell using the electrode material according to Comparative Example 1 as described above. That is, Fig. 17, Fig. 18, and Fig. 9 show Nyquist plot data obtained by measuring the cells according to Example 22, Comparative Example 3, and Comparative Example 1 by the AC impedance method, respectively.

[0225] As shown in FIG. 17, the real number (refer to R4 in FIG. 17) from the high-frequency side intersection point (refer to I3 in FIG. 17) between the real axis (refer to the dashed line in FIG. 17, i.e., y = 0) and the arc drawn with the change of frequency to the low-frequency end (refer to I4 in FIG. 17) was calculated. The value obtained by halving this real number R4 is the reaction resistance (unit: Ωcm 2 ).

[0226] Also, as shown in FIGS. 18 and 9, the Nyquist plots according to Comparative Example 3 and Comparative Example 1 do not have an intersection point between the real axis and the arc drawn with the change of wave number. In this case, as shown in FIGS. 18 and 9, the real numbers (refer to R5 in FIG. 18 and R2 in FIG. 9) from the minimum point to the low-frequency end were calculated. The values obtained by halving these real numbers R5 and R2 were used as the reaction resistance.

[0227] The reaction resistance read from FIGS. 17, 18, and 9 is clearly smaller for the cell according to Example 22 than for the cells according to Comparative Example 3 and Comparative Example 1. That is, the electrodes of the cell according to Example 22 have excellent performance. As a reason, it is considered that Co in the electrode material according to Example 22 functioned as an electrode active site. On the other hand, the electrode materials according to Comparative Example 3 and Comparative Example 1 have low functionality as electrodes.

[0228] Thus, it is considered that by adding Co to the compound represented by the chemical formula BaZr 1-x M x O 3-δ (where the element M is a trivalent substitution element, 0 < x < 1, and 0 < δ < 0.5) used as an electrolyte material having proton conductivity, an electrode material with excellent effects can be provided.

[0229] (Evaluation of the reaction resistance of the cells according to Example 22 and Comparative Example 2) The results of evaluating the reaction resistance of the cells according to Example 22 and Comparative Example 2 using FIGS. 17, 10, and Table 2 will be described.

[0230] Figure 10 shows the Nyquist plot of the evaluation cell using the electrode material according to Comparative Example 2 as described above. That is, Figure 10 shows the data of the Nyquist plot obtained by measuring the cell according to Comparative Example 2 by the AC impedance method. The electrode material according to Comparative Example 2 is known to have excellent electrode activity as a mixed conductor of oxide ions and electrons. The electrode material according to Comparative Example 2 is a material often used for the air electrode of SOFC.

[0231] The Nyquist plot of the cell according to Comparative Example 2 showed a similar tendency to the Nyquist plot of the cell according to Example 22. That is, as an AC signal was applied from high frequency to low frequency, the resistance value tended to draw a semicircle.

[0232] The reaction resistance of the cell according to Example 22 was 0.06 Ωcm 2 On the other hand, the reaction resistance of the cell according to Comparative Example 2 was 0.49 Ωcm 2 The reaction resistance of the cell according to Example 1 was lower than that of the cell according to Comparative Example 2. Therefore, by using the cell according to Example 22 in various electrochemical devices, high electrode activity is expected. The fuel cell using the electrode material according to Example 22 is expected to have high output.

[0233] (Summary and Discussion) Referring to Table 2, the evaluation results of the cells of Examples 22 to 48 and Comparative Examples 1 to 3 will be described.

[0234] As shown in Table 1, the electrode material containing the compound represented by the chemical formula BaZr 1-x-y Yb x Co y O 3-δ (where 0 < x < 1, 0 < y < 1, (x + y) < 1 and 0 < δ < 1) was synthesized as an electrode material composed of a single compound or as an electrode material composed of a mixture of the above compound and other compounds depending on the values of x and y.

[0235] The chemical formula BaZr 1-x-y Yb xCo y O 3-δ (0 < x < 1, 0 < y < 1, (x + y) < 1, 0 < δ < 1) The electrode material containing the compound represented by is, for example, BaZr disclosed as a proton conductive material in Patent Document 1 1-x M x O 3-p corresponds to the material with Co added to. Chemical formula BaZr 1-x-y Yb x Co y O 3-δ (0 < x < 1, 0 < y < 1, (x + y) < 1, 0 < δ < 1) The electrode material containing the Co-containing compound represented by is BaZr 1-x M x O 3-p could achieve a lower reaction resistance. Specifically, the electrode materials according to Examples 22 to 48 had a lower reaction resistance than BaZr of Comparative Example 3 0.8 Yb 0.2 O 3-δ .

[0236] Also, the electrode material containing the compound represented by the chemical formula BaZr 1-x-y Yb x Co y O 3-δ (0 < x < 1, 0 < y < 1, (x + y) < 1, 0 < δ < 1) had a lower reaction resistance than the electrode material according to Comparative Example 2 depending on the composition. That is, for the electrode material of the present disclosure, it was found that it was possible to achieve a lower reaction resistance than the conventional electrode material having excellent electrode activity as a mixed conductor of oxide ions and electrons. Specifically, the values of the reaction resistance of the electrodes according to Examples 22, 25 to 41, and 44 to 48 were smaller than the reaction resistance of the electrode according to Comparative Example 2. As a possible reason for this result, it is considered that the electrode materials according to Examples 22, 25 to 41, and 44 to 48 are mixed conductors of protons and electrons. In the evaluation of the reaction resistance here, a material having proton conductivity, that is, BaZr 0.8 Yb 0.2 O 2.9was used as the material of the electrolyte membrane. When a material not having proton conductivity is used as an electrode for this electrolyte membrane as in Comparative Example 3, the interface where the electrons conducting the electrode, the protons conducting the electrolyte membrane, and the oxygen gas come into contact (i.e., the three-phase interface) becomes the region where the reaction proceeds. The oxygen gas at this time may be derived from air, for example, or a synthetic gas in which oxygen and gas such as nitrogen are mixed at any ratio may be used. On the other hand, when the electrode material has proton conductivity, the surface of the electrode particles (i.e., the two-phase interface) also becomes the region where the reaction proceeds. Generally, in cells of the same size, the area of ​​the three-phase interface is smaller than the area of ​​the two-phase interface. Therefore, by using the electrode material of the present disclosure in a cell equipped with an electrolyte membrane having proton conductivity as in Example 22, this cell has very excellent electrode performance. By using the cells using the electrode materials according to Examples 22, 25 to 41, and Examples 44 to 48 in various electrochemical devices, high electrode activity is expected. The fuel cells using the electrode materials according to Example 22, Examples 25 to 41, and Examples 44 to 48 are expected to have high output.

[0237] In the above embodiments and examples, the values ​​of x and y indicate the amounts of charge, and may have an error of -0.02 or more and +0.02 or less from the values ​​of the actual measured amounts. Therefore, the range of the values ​​of x and y shown above may include an error of -0.02 or more and +0.02 or less. The value of the actual measured amount may be obtained, for example, by measuring the measurement sample by ICP emission spectroscopy. The measurement sample may be, for example, a sample related to the value of x or y, added with hydrochloric acid and nitric acid, subjected to microwave treatment, and after confirming the dissolution of the sample, diluted to a constant volume with ion-exchanged water.

[0238] [Table 2] [Industrial Applicability]

[0239] The electrode material according to the present disclosure is suitable for systems using electrochemical cells in hydrogen generation systems or fuel cell systems. The electrode material according to the present disclosure may also be used in electrochemical hydrogen pumps, such as hydrogen purification devices and hydrogen compression devices. [Explanation of symbols]

[0240] 10 Membrane electrode assembly 11 Electrolyte membrane 12a First main surface 12 1st electrode 13 Second electrode 20 Electrochemical Cell 30 Stack 1000 Fuel Cell System 1014 Case 1021 Oxidant gas supply 1022 Raw material feeder 1023 Raw material gas supply route 1024 Oxidant gas supply route

Claims

1. A membrane electrode assembly, a first electrode comprising an electrode material; and an electrolyte membrane provided on a first main surface of the first electrode; Equipped with The electrode material is The compound has the chemical formula BaZr1-xyMxCoyO3-δ, where M is In, 0<x<1, 0<y<1, 0<(x+y)<1, and 0<δ<1 are satisfied; The chemical formula satisfies the following formulas (1) to (3): Formula (1): 0.125≦y≦0.5 Formula (2): y≦3x−0.25 Formula (3): y≦−3x+2 The electrolyte membrane includes a proton-conducting electrolyte material. Membrane electrode assembly.

2. A membrane electrode assembly, a first electrode comprising an electrode material; and an electrolyte membrane provided on a first main surface of the first electrode; Equipped with The electrode material is The compound has the chemical formula BaZr1-xyMxCoyO3-δ, where M is In, 0<x<1, 0<y<1, 0<(x+y)<1, and 0<δ<1 are satisfied; The chemical formula satisfies the following formulas (4) to (7): Formula (4): 0.125≦y≦0.375 Formula (5): 0.25≦x≦0.5 Formula (6): y ≧ −x + 0.5 Formula (7): y≦−x+0.75 The electrolyte membrane includes a proton-conducting electrolyte material. Membrane electrode assembly.

3. A membrane electrode assembly, a first electrode comprising an electrode material; and an electrolyte membrane provided on a first main surface of the first electrode; Equipped with The electrode material is The compound has the chemical formula BaZr1-xyMxCoyO3-δ, where M is In, 0<x<1, 0<y<1, 0<(x+y)<1, and 0<δ<1 are satisfied; The chemical formula satisfies the following formulas (8) to (11): Formula (8): 0.25≦x≦0.5 Formula (9): y≦0.375 Formula (10): y≦−x+0.75 Formula (11): y ≧ −0.5x + 0.375 The electrolyte membrane includes a proton-conducting electrolyte material. Membrane electrode assembly.

4. A membrane electrode assembly, a first electrode comprising an electrode material; and an electrolyte membrane provided on a first main surface of the first electrode; Equipped with The electrode material is The compound has the chemical formula BaZr1-xyMxCoyO3-δ, where M is Yb, 0<x<1, 0<y<1, 0<(x+y)<1, and 0<δ<1 are satisfied; The chemical formula satisfies the following formulas (12) to (15): Formula (12): 0.075≦x≦0.625 Formula (13): 0.125≦y Formula (14): y≦12.5x−0.6875 Formula (15): y≧x−0.375 The electrolyte membrane includes a proton-conducting electrolyte material. Membrane electrode assembly.

5. A membrane electrode assembly, a first electrode comprising an electrode material; and an electrolyte membrane provided on a first main surface of the first electrode; Equipped with The electrode material is The compound has the chemical formula BaZr1-xyMxCoyO3-δ, where M is Yb, 0<x<1, 0<y<1, 0<(x+y)<1, and 0<δ<1 are satisfied; The chemical formula satisfies the following formulas (12) to (16): Formula (12): 0.075≦x≦0.625 Formula (13): 0.125≦y Formula (14): y≦12.5x−0.6875 Formula (15): y≧x−0.375 Formula (16): y ≧ −2.5x + 0.4375 The electrolyte membrane includes a proton-conducting electrolyte material. Membrane electrode assembly.

6. The electrolyte membrane has the chemical formula BaZr 1-x1 M1 x1 O 3-δ A compound represented by the chemical formula BaCe 1-x2 M2 x2 O 3-δ Compounds represented by the chemical formula BaZr 1-x3-y3 C x3 M3 y3 O 3-δ The compound includes at least one selected from the group consisting of compounds represented by M1, M2 and M3 each include at least one selected from the group consisting of Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Y, Sc, In and Lu; The following are satisfied: 0<x1<1, 0<x2<1, 0<x3<1, 0<y3<1, and 0<δ<0.

5. The membrane electrode assembly according to claim 1 .

7. The membrane electrode assembly of claim 6 , wherein M1 is Yb.

8. 1. An electrochemical cell comprising: The membrane electrode assembly according to any one of claims 1 to 7, and Second electrode Equipped with The first electrode, the electrolyte membrane, and the second electrode are provided in this order. Electrochemical cell.

9. The second electrode includes at least one selected from the group consisting of NiO and Ni.

9. The electrochemical cell of claim 8.

10. 1. A fuel cell system comprising:

10. An electrochemical cell according to claim 8 or 9, An oxidant gas supply path, and A raw material gas supply path, Equipped with the first electrode is connected to the oxidant gas supply path, The second electrode is connected to the source gas supply path. Fuel cell system.

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