Proton conductor, electrolyte membrane, membrane electrode assembly, electrochemical cell, and fuel cell stack

Abstract

The proton conductor of the present disclosure contains a compound represented by the chemical formula BaZr (1‑x‑y) Yb x Sc y O 3‑δ denotes a compound represented by the chemical formula BaZr 0

Description

Technical Field

[0001] The present disclosure relates to a proton conductor, an electrolyte membrane, a membrane electrode assembly, an electrochemical unit, and a fuel cell stack. Background Art

[0002] As an electrolyte material having proton conductivity, BaZr is known. 1-x M x O 3-α The perovskite-type composite oxide represented by In this chemical formula, M is a trivalent substituent element.

[0003] Patent Document 1 discloses a method of preparing a molten metal having the chemical formula BaZr 0.85 Y 0.15 O3 or BaZr 0.85 Y 0.10 Sc 0.05 According to Patent Document 1, a proton conductor represented by the chemical formula BaZr 1-x M x O 3-α The addition of Sc to the proton conductor shown above promotes crystal growth during sintering, resulting in a proton conductor with a large grain size. As a result, the proportion of grain boundaries, which have a higher resistance than that within the grains, is reduced, thereby reducing the overall resistance of the proton conductor.

[0004] Prior art literature

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2009-23883 Summary of the Invention

[0006] As described above, Patent Document 1 discloses a proton conductor in which the overall resistance is reduced by increasing the crystal grain size. However, in order to further reduce the resistance of the proton conductor, it is required to improve the proton conductivity of the proton conductor material itself.

[0007] An object of the present disclosure is to provide a proton conductor having high proton conductivity.

[0008] The proton conductor of the present disclosure contains a proton conductor having the chemical formula BaZr (1-x-y) Yb x Sc y O 3-δ A compound represented by <x<0.5、0<y<0.5、(x+y)<0.5和0<δ<0.5。

[0009] The present disclosure provides a proton conductor with high proton conductivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 A cross-sectional view of a membrane electrode assembly according to a second embodiment is shown.

[0011] Figure 2 A cross-sectional view of an electrochemical cell according to Embodiment 3.

[0012] Figure 3 A fuel cell system according to Embodiment 4.

[0013] Figure 4 A flow chart showing an example of a method for producing a proton conductor according to the present embodiment.

[0014] Figure 5 A sequence for producing an electrochemical cell using the proton conductor according to Embodiment 13. DETAILED DESCRIPTION

[0015] (Embodiment 1)

[0016] The proton conductor according to Embodiment 1 contains a compound represented by the chemical formula BaZr (1-x-y) Yb x Sc y O 3-δ where the chemical formula satisfies 0 < x < 0.5, 0 < y < 0.5, (x + y) < 0.5, and 0 < δ < 0.5.

[0017] As demonstrated in Examples 1 to 10 described later, the proton conductor according to Embodiment 1 becomes a dense body due to firing because the mathematical formula (x + y) < 0.5 is satisfied. If the value of (x + y) is 0.5 or more, cracking occurs at the time of producing pellets as demonstrated in Comparative Example 1 described later. In addition, as demonstrated in Comparative Examples 2 to 8, the proton conductors having a combination of dopants other than Yb and Sc have a lower proton conductivity than the proton conductors having the same composition ratio of dopants and the combination of dopants of Yb and Sc. Here, the "same composition ratio of dopants" in the comparison with each other means that the molar ratio of dopants in the proton conductor is the same.

[0018] As described above, the proton conductor according to Embodiment 1 containing the above-described compound has a higher proton conductivity than the proton conductors having the same composition ratio of dopants as the proton conductor according to Embodiment 1 and having a combination of dopants other than Yb and Sc.

[0019] It is preferable that, in the chemical formula BaZr (1-x-y) Yb x Sc y O 3-δ the mathematical formula y < x be satisfied.

[0020] As demonstrated by the comparison of Examples 1 and 2 described later, the comparison of Examples 4 and 6, and the comparison of Examples 5 and 8, the proton conductor according to Embodiment 1 has a higher proton conductivity in the case where the mathematical formula y < x is satisfied.

[0021] In addition, preferably in the chemical formula BaZr (1-x-y) Yb x Sc y O 3-δ , the mathematical formula is satisfied: (x+y)≥0.15.

[0022] As demonstrated in Examples 1 to 10 described later, the proton conductor of the first embodiment has high proton conductivity when the mathematical formula: (x+y)≥0.15 is satisfied.

[0023] In addition, preferably in the chemical formula BaZr (1-x-y) Yb x Sc y O 3-δ , the mathematical formula is satisfied: (x+y)≥0.25.

[0024] As demonstrated in Examples 4 to 10 described later, when the mathematical formula: (x+y)≥0.25 is satisfied, the proton conductor of the first embodiment has higher proton conductivity.

[0025] In addition, preferably in the chemical formula BaZr (1-x-y) Yb x Sc y O 3-δ , the mathematical formula (x+y)≤0.35 is satisfied.

[0026] As demonstrated in Examples 1 to 8 described later, the proton conductor of the first embodiment has high proton conductivity when the mathematical expression (x+y)≤0.35 is satisfied.

[0027] In addition, preferably in the chemical formula BaZr (1-x-y) Yb x Sc y O 3-δ , the mathematical formula x≥0.15 is satisfied.

[0028] As demonstrated in Examples 6 to 10 described later, when the mathematical expression: x ≥ 0.15 is satisfied, the proton conductor of the first embodiment has high proton conductivity.

[0029] More preferably, in the chemical formula BaZr (1-x-y) Yb x Sc y O 3-δ , x=0.2 and y=0.1.

[0030] As demonstrated in Example 8 described later, the proton conductor of Embodiment 1 has the highest proton conductivity when x=0.2 and y=0.1 are satisfied.

[0031] The proton conductor of Embodiment 1 can be synthesized by a citric acid complex method, a solid phase sintering method, a coprecipitation method, a nitrate method, or a spray granulation method.

[0032] The proton conductor of Embodiment 1 contains a compound represented by the chemical formula BaZr (1-x-y) Yb x Sc y O 3-δ The proton conductor of Embodiment 1 can contain, for example, 5% or more of a compound represented by the chemical formula BaZr (1-x-y) Yb x Sc y O 3-δ The proton conductor of Embodiment 1 can contain 20% or more. The proton conductor of Embodiment 1 can exhibit high proton conductivity by containing a compound represented by the chemical formula BaZr (1-x-y) Yb x Sc y O 3-δ The proton conductor of Embodiment 1 can exhibit high proton conductivity by containing a compound represented by the chemical formula BaZr

[0033] The proton conductor of Embodiment 1 can also be composed of a compound represented by the chemical formula BaZr (1-x-y) Yb x Sc y O 3-δ The proton conductor of Embodiment 1 is composed of a compound represented by the chemical formula BaZr (1-x-y) Yb x Sc y O 3-δ The proton conductor of Embodiment 1 is composed of a compound represented by the chemical formula BaZr (1-x-y) Yb x Sc y O 3-δ The proton conductor of Embodiment 1 is composed of a compound represented by the chemical formula BaZr (1-x-y) Yb x Sc y O 3-δ The proton conductor of Embodiment 1 can exhibit higher proton conductivity when composed of a compound represented by the chemical formula BaZr

[0034] The proton conductor of Embodiment 1 can also be composed of a compound represented by the chemical formula BaZr (1-x-y) Yb x Sc y O 3-δ The proton conductor of Embodiment 1 is composed of a compound represented by the chemical formula BaZr (1-x-y) Yb x Sc y O3-δ "Composed of compounds represented by" means that the proton conductor of the first embodiment consists only of the compound represented by the chemical formula BaZr (1-x-y) Yb x Sc y O 3-δ In this case, in the proton conductor of the first embodiment, the compound represented by the chemical formula BaZr (1-x-y) Yb x Sc y O 3-δ The molar ratio of the compound represented may be 95% or more.

[0035] The proton conductor of embodiment 1 is of the chemical formula BaZr (1-x-y) Yb x Sc y O 3-δ In addition to the compounds shown above, other components may be contained. The proton conductor of Embodiment 1 may further contain, as other components, impurities generated during the synthesis of the above-mentioned compounds.

[0036] The proton conductor of the first embodiment contains a compound having the chemical formula BaZr (1-x-y) Yb x Sc y O 3-δ The average crystal particle size of the compound represented is, for example, 0.1 μm or more and 10 μm or less. Furthermore, the proton conductor of Embodiment 1 can achieve high proton conductivity regardless of whether the average crystal particle size is within the above range or less than 0.1 μm. Here, the average crystal particle size can be determined, for example, using the median diameter (volume basis) obtained by measuring the particle size distribution.

[0037] (Implementation Method 2)

[0038] Figure 1 A cross-sectional view of a membrane electrode assembly 10 according to Embodiment 2 is shown. The membrane electrode assembly 10 includes an electrolyte membrane 11 and a first electrode 12 . The first electrode 12 is provided on a first main surface 11 a of the electrolyte membrane 11 .

[0039] The electrolyte membrane 11 contains the proton conductor described in Embodiment 1 as an electrolyte material. The electrolyte membrane 11 may further contain a proton conductor having a chemical formula of BaZr (1-x-y) Yb x Sc y O 3-δ Other compounds showing proton conductivity other than the compounds represented by 1-x1 M1 x1 O 3-δThe compound represented by the chemical formula BaCe 1-x2 M2 x2 O 3-δ A compound represented by or having the chemical formula BaZr 1-x3-y3 Ce x3 M3 y3 O 3-δ wherein M1, M2, and M3 each contain at least one selected from Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Y, Sc, In, and Lu, and satisfy 0 <x1<1、0<x2<1、0<x3<1、0<y3<1和0<δ<0.5。电解质膜11可以还包含质子导体以外的电解质材料。

[0040] The thickness of the electrolyte membrane 11 is, for example, 1 to 50 μm.

[0041] For example, the first electrode 12 may mainly contain at least one of the following compounds.

[0042] (i) The electrolyte material contained in the electrolyte membrane 11 and a mixture of one or more metals selected from Co, Fe, Pt, and Pt and Ni (ie, cermet).

[0043] (ii) Composite oxides containing lanthanum

[0044] (iii) Barium-containing composite oxides

[0045] (iv) Composite oxides containing strontium

[0046] The first electrode 12 mainly contains a certain compound, which means that the mass ratio of the compound in the first electrode 12 is the largest.

[0047] The thickness of the first electrode 12 is, for example, 1 to 1000 μm. When the first electrode 12 also serves as a cell support, the thickness of the first electrode 12 is preferably 100 to 700 μm. When a structure other than the first electrode 12 serves as a cell support, the thickness of the first electrode 12 is preferably 10 to 50 μm.

[0048] Figure 2 In the embodiment, 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 such another layer is a functional layer. The functional layer is a layer that facilitates the movement of electrons or protons between the electrolyte membrane 11 and the first electrode 12. The functional layer is composed, for example, of a composite material of a cermet and a composite oxide.

[0049] The electrolyte membrane 11 is produced by, for example, a tape casting method, a spin coating method, a dip coating method, sputtering, or PLD (Pulse Laser Deposition).

[0050] (Implementation 3)

[0051] Figure 2 A cross section of an electrochemical cell 20 according to a third embodiment is shown.

[0052] The electrochemical cell 20 of the third embodiment includes the membrane electrode assembly 10 and the second electrode 13 . Specifically, the electrochemical cell 20 includes the first electrode 12 , the electrolyte membrane 11 , and the second electrode 13 .

[0053] The membrane electrode assembly 10 has been described in the second embodiment.

[0054] like Figure 2 As shown, the electrochemical cell 20 includes a first electrode 12, an electrolyte membrane 11, and a second electrode 13 in this order. Specifically, 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.

[0055] The electrochemical cell 20 of the third embodiment can be used as a fuel cell, for example. Therefore, for example, the first electrode 12 can be used as a fuel electrode, and the second electrode 13 can be used as an air electrode.

[0056] When the second electrode 13 is used as an air electrode, the second electrode 13 contains a composite compound. For example, the second electrode 13 mainly contains lanthanum strontium cobalt oxide. The second electrode 13 can be provided on the membrane electrode assembly 10 by screen printing, for example.

[0057] like Figure 2 As shown, the second electrode 13 is provided in contact with the electrolyte membrane 11 , but the present invention is not limited thereto. Another layer may be provided between the second electrode 13 and the electrolyte membrane 11 .

[0058] As another layer, for example, a functional layer can be mentioned. The functional layer has been described in the second embodiment.

[0059] The electrochemical cell 20 can be used in a fuel cell, an electrochemical hydrogen pump, a hydrogen sensor, and a water electrolysis device.

[0060] (Implementation 4)

[0061] Figure 3 A fuel cell system 1000 according to a fourth embodiment is schematically shown.

[0062] The fuel cell system 1000 includes the electrochemical cell 20. The electrochemical cell 20 has been described in the third embodiment.

[0063] In the fuel cell system 1000 of the fourth embodiment, the electrochemical cell 20 is used as a fuel cell. Therefore, in this case, the first electrode 12 is used as a fuel electrode, and the second electrode 13 is used as an air electrode.

[0064] The fuel cell system 1000 further includes an oxidant gas supply path 1024 and a raw material gas supply path 1023. The oxidant gas supply path 1024 is connected to the second electrode 13 and the oxidant gas supplier 1021. The raw material gas supply path 1023 is connected to the first electrode 12 and the raw material supplier 1022.

[0065] The electrochemical cells 20 are stacked to form a fuel cell stack 30. That is, the fuel cell stack 30 includes a plurality of electrochemical cells 20. High power is obtained by the fuel cell stack 30. The fuel cell stack 30 is housed in a housing 1014.

[0066] The frame 1014 may be formed of a heat insulating member. The oxidizing gas is supplied to the first electrodes 12 of the stacked electrochemical cells 20 .

[0067] Specifically, the oxidant gas is supplied from the oxidant gas supplier 1021 to the second electrodes 13 (ie, cathodes) of the plurality of electrochemical cells 20 through the oxidant gas supply path 1024 .

[0068] In the second electrode 13 , the following reaction (1) proceeds.

[0069] O2+4H + +4e - →2H2O (1)

[0070] The oxidant gas is, for example, air.

[0071] The raw material is supplied from the raw material supplier 1022 to the first electrodes 12 of the plurality of electrochemical cells 20 through the raw material gas supply path 1023 .

[0072] In the first electrode 12 , the following reaction (2) proceeds.

[0073] 2H2→4H + +4e - (2)

[0074] The starting material is, for example, molecular hydrogen.

[0075] Hydrogen can be generated through modification reactions or through hydrolysis.

[0076] In this way, the fuel cell system 1000 operates and then generates power.

[0077] (Example)

[0078] Hereinafter, the present disclosure will be described in detail with reference to the following Examples and Comparative Examples.

[0079] <Proton Conductor>

[0080] As described below, in Examples and Comparative Examples, proton conductors and evaluation particles using the same were produced, and the properties of the proton conductors were evaluated using the evaluation particles.

[0081] [Example 1]

[0082] (Fabrication of Proton Conductors)

[0083] Figure 4 This is a flow chart showing an example of a method for producing a proton conductor according to an embodiment. Figure 4 The production of the proton conductor will be described.

[0084] As starting materials for the proton conductor, the following materials were prepared.

[0085] Ba(NO3)2 (manufactured by Kanto Chemical Co., Ltd.) 0.100 mol

[0086] ZrO(NO3)2·2H2O (manufactured by Kanto Chemical Co., Ltd.) 0.085 mol

[0087] Yb(NO3)3·xH2O(2 <x<6、高纯度化学株式会社制)0.005mol

[0088] Sc(NO3)3·xH2O(2 <x<6、高纯度化学株式会社制)0.010mol

[0089] The above starting materials were added to 1000 mL of distilled water to dissolve them to obtain a mixed solution, and the mixed solution was stirred (S11).

[0090] Next, 0.3 mol of citric acid monohydrate (manufactured by Kanto Chemical Co., Ltd.) and 0.3 mol of ethylenediaminetetraacetic acid (manufactured by Kanto Chemical Co., Ltd.) were added to the mixed solution (S12). Hereinafter, "ethylenediaminetetraacetic acid" will be referred to as "EDTA."

[0091] Next, aqueous ammonia (28% by mass, manufactured by Kanto Chemical Co., Ltd.) was added to the mixed solution, and the pH of the mixed solution was adjusted to 7 using a pH meter (manufactured by Horiba, Ltd.) ( S13 ).

[0092] Next, the mixed liquid is stirred at a temperature of 90° C. ( S14 ).

[0093] After adjusting the pH of the mixed solution to 7, the temperature of the mixed solution was increased from 95°C to 240°C using a hot stirrer (S15). Then, the solvent (i.e., water) was evaporated from the mixed solution. In this way, the water was removed from the mixed solution to obtain a solid component.

[0094] The obtained solid component was pulverized in a mortar and then debindering at a temperature of about 400°C (S16). In this way, a powder was obtained.

[0095] The obtained powder was pressed into a cylindrical shape using an oil pressure pump (manufactured by Enplas Corporation) and a powder molding mold having a diameter of 30 mm. In this way, a cylindrical shaped product was obtained.

[0096] Then, the obtained cylindrical shaped product was calcined at 900°C for 10 hours in an atmosphere (S17). In this way, a calcined powder was obtained.

[0097] Then, the calcined powder was pulverized (S18). Next, the pulverized powder was moved to a plastic container together with zirconia balls.

[0098] Then, 100 g of ethanol (manufactured by Showa Denko K.K.) was added to the plastic container. In this way, a mixed solution was obtained. Next, the mixed solution was pulverized using a ball mill for 96 hours (S19).

[0099] After pulverization using the ball mill, the mixed solution was dried using a lamp to remove ethanol from the mixed solution (S20). In this way, a powder was obtained.

[0100] The obtained powder was main calcined at 1200°C for 5 hours in an atmosphere (S21).

[0101] Through the above sequence, a proton conductor of Example 1 was produced.

[0102] (Production of pellets for evaluation)

[0103] First, the powder of the proton conductor produced using the above method was vacuum dried at 200°C for 12 hours.

[0104] Next, the obtained powder was pressed into a cylindrical shape using an oil pressure pump (manufactured by Enplas Corporation) and a powder molding mold having a diameter of 30 mm, and then formed into a pellet by cold isostatic pressing (manufactured by Sanai Sangyo) at a pressing pressure of 200 MPa.

[0105] The obtained round pellet was calcined at 1600°C for 10 hours in an oxygen atmosphere. In this way, a sintered body pellet was obtained.

[0106] The obtained sintered pellets were cut into discs with a thickness of approximately 500 μm using a low-speed cutter (IsoMet 4000). This yielded pellets for evaluation. Both surfaces of the pellets for evaluation were polished using a 3 μm abrasive film.

[0107] Then, Ag paste (produced by Tanaka Kikinzoku Kogyo) was applied to both sides of the polished surface of the evaluation particles by screen printing. The diameter of the applied Ag paste was 10 mm.

[0108] Then, the evaluation pellets coated with the Ag paste were fired in an air atmosphere at 900° C. for 1 hour. In this manner, evaluation pellets of Example 1 were produced.

[0109] (Evaluation of proton conductivity)

[0110] The proton conductivity of the proton conductor was calculated from the resistance and thickness of the particles using the evaluation particles of Example 1. The resistance of the particles was measured by the AC impedance method. The proton conductivity was determined as follows.

[0111] Using a Solartron 1287 (manufactured by Solartron Analytical), an AC signal was applied to the pellets at a frequency range of 1 MHz to 0.01 Hz with an amplitude of 10 mV. The measurement was performed at 400°C and 600°C in a humidified hydrogen atmosphere. A Cole-Cole plot was then output. Based on the arc of the output Cole-Cole plot, the intersection of the arc and the real axis was determined. The real axis refers to the axis in the Cole-Cole plot where the Y-axis value is 0. The intersection on the high-frequency side of the obtained intersections was used as the pellet's resistance.

[0112] The proton conductivity of the proton conductor is calculated based on the obtained resistance and the thickness of the particles.

[0113] [Example 2]

[0114] In Example 2, a proton conductor and evaluation particles were prepared in the same manner as in Example 1 except for the following item (1), and the proton conductivity was evaluated.

[0115] (1) The starting materials of the proton conductor were changed to the following materials.

[0116] Ba(NO3)2 (manufactured by Kanto Chemical Co., Ltd.) 0.100 mol

[0117] ZrO(NO3)2·2H2O (manufactured by Kanto Chemical Co., Ltd.) 0.085 mol

[0118] Yb(NO3)3·xH2O(2 <x<6、高纯度化学株式会社制)0.010mol

[0119] Sc(NO3)3·xH2O(2 <x<6、高纯度化学株式会社制)0.005mol

[0120] [Example 3]

[0121] In Example 3, a proton conductor and evaluation particles were prepared in the same manner as in Example 1 except for the following item (1), and the proton conductivity was evaluated.

[0122] (1) The starting materials of the proton conductor were changed to the following materials.

[0123] Ba(NO3)2 (manufactured by Kanto Chemical Co., Ltd.) 0.100 mol

[0124] ZrO(NO3)2·2H2O (manufactured by Kanto Chemical Co., Ltd.) 0.080 mol

[0125] Yb(NO3)3·xH2O(2 <x<6、高纯度化学株式会社制)0.010mol

[0126] Sc(NO3)3·xH2O(2 <x<6、高纯度化学株式会社制)0.010mol

[0127] [Example 4]

[0128] In Example 4, a proton conductor and evaluation particles were prepared in the same manner as in Example 1 except for the following item (1), and the proton conductivity was evaluated.

[0129] (1) The starting materials of the proton conductor were changed to the following materials.

[0130] Ba(NO3)2 (manufactured by Kanto Chemical Co., Ltd.) 0.100 mol

[0131] ZrO(NO3)2·2H2O (manufactured by Kanto Chemical Co., Ltd.) 0.075 mol

[0132] Yb(NO3)3·xH2O(2 <x<6、高纯度化学株式会社制)0.010mol

[0133] Sc(NO3)3·xH2O(2 <x<6、高纯度化学株式会社制)0.015mol

[0134] [Example 5]

[0135] In Example 5, a proton conductor and evaluation particles were prepared in the same manner as in Example 1 except for the following item (1), and the proton conductivity was evaluated.

[0136] (1) The starting materials of the proton conductor were changed to the following materials.

[0137] Ba(NO3)2 (manufactured by Kanto Chemical Co., Ltd.) 0.100 mol

[0138] ZrO(NO3)2·2H2O (manufactured by Kanto Chemical Co., Ltd.) 0.070 mol

[0139] Yb(NO3)3·xH2O(2 <x<6、高纯度化学株式会社制)0.010mol

[0140] Sc(NO3)3·xH2O(2 <x<6、高纯度化学株式会社制)0.020mol

[0141] [Example 6]

[0142] In Example 6, a proton conductor and evaluation particles were prepared in the same manner as in Example 1 except for the following item (1), and the proton conductivity was evaluated.

[0143] (1) The starting materials of the proton conductor were changed to the following materials.

[0144] Ba(NO3)2 (manufactured by Kanto Chemical Co., Ltd.) 0.100 mol

[0145] ZrO(NO3)2·2H2O (manufactured by Kanto Chemical Co., Ltd.) 0.075 mol

[0146] Yb(NO3)3·xH2O(2 <x<6、高纯度化学株式会社制)0.015mol

[0147] Sc(NO3)3·xH2O(2 <x<6、高纯度化学株式会社制)0.010mol

[0148] [Example 7]

[0149] In Example 7, a proton conductor and evaluation particles were prepared in the same manner as in Example 1 except for the following item (1), and the proton conductivity was evaluated.

[0150] (1) The starting materials of the proton conductor were changed to the following materials.

[0151] Ba(NO3)2 (manufactured by Kanto Chemical Co., Ltd.) 0.100 mol

[0152] ZrO(NO3)2·2H2O (manufactured by Kanto Chemical Co., Ltd.) 0.075 mol

[0153] Yb(NO3)3·xH2O(2 <x<6、高纯度化学株式会社制)0.020mol

[0154] Sc(NO3)3·xH2O(2 <x<6、高纯度化学株式会社制)0.005mol

[0155] [Example 8]

[0156] In Example 8, a proton conductor and evaluation particles were prepared in the same manner as in Example 1 except for the following item (1), and the proton conductivity was evaluated.

[0157] (1) The starting materials of the proton conductor were changed to the following materials.

[0158] Ba(NO3)2 (manufactured by Kanto Chemical Co., Ltd.) 0.100 mol

[0159] ZrO(NO3)2·2H2O (manufactured by Kanto Chemical Co., Ltd.) 0.070 mol

[0160] Yb(NO3)3·xH2O(2 <x<6、高纯度化学株式会社制)0.020mol

[0161] Sc(NO3)3·xH2O(2 <x<6、高纯度化学株式会社制)0.010mol

[0162] [Example 9]

[0163] In Example 9, a proton conductor and evaluation particles were prepared in the same manner as in Example 1 except for the following item (1), and the proton conductivity was evaluated.

[0164] (1) The starting materials of the proton conductor were changed to the following materials.

[0165] Ba(NO3)2 (manufactured by Kanto Chemical Co., Ltd.) 0.100 mol

[0166] ZrO(NO3)2·2H2O (manufactured by Kanto Chemical Co., Ltd.) 0.060 mol

[0167] Yb(NO3)3·xH2O(2 <x<6、高纯度化学株式会社制)0.020mol

[0168] Sc(NO3)3·xH2O(2 <x<6、高纯度化学株式会社制)0.020mol

[0169] [Example 10]

[0170] In Example 10, a proton conductor and evaluation particles were prepared in the same manner as in Example 1 except for the following item (1), and the proton conductivity was evaluated.

[0171] (1) The starting material of the proton conductor was changed to the following material.

[0172] Ba(N03)2 (manufactured by Kanto Chemical Co., Inc.) 0.100 mol

[0173] ZrO(N03)2-2H20 (manufactured by Kanto Chemical Co., Inc.) 0.065 mol

[0174] Yb(N03)3-xH20 (2 < x < 6, manufactured by High Purity Standards, Inc.) 0.025 mol

[0175] Sc(N03)3-xH20 (2 < x < 6, manufactured by High Purity Standards, Inc.) 0.010 mol

[0176] [Comparative Example 1]

[0177] In Comparative Example 1, the same method as in Example 1 was employed to produce the proton conductor and the evaluation particles, except for the following matter (1), and the proton conductivity was evaluated.

[0178] (1) The starting material of the proton conductor was changed to the following material.

[0179] Ba(N03)2 (manufactured by Kanto Chemical Co., Inc.) 0.100 mol

[0180] ZrO(N03)2-2H20 (manufactured by Kanto Chemical Co., Inc.) 0.050 mol

[0181] Yb(N03)3-xH20 (2 < x < 6, manufactured by High Purity Standards, Inc.) 0.030 mol

[0182] Sc(N03)3-xH20 (2 < x < 6, manufactured by High Purity Standards, Inc.) 0.020 mol

[0183] [Comparative Example 2]

[0184] In Comparative Example 2, the same method as in Example 1 was employed to produce the proton conductor and the evaluation particles, except for the following matter (1), and the proton conductivity was evaluated.

[0185] (1) The starting material of the proton conductor was changed to the following material.

[0186] Ba(N03)2 (manufactured by Kanto Chemical Co., Inc.) 0.100 mol

[0187] ZrO(N03)2-2H20 (manufactured by Kanto Chemical Co., Inc.) 0.070 mol

[0188] Y(N03)3-xH20 (2 < x < 6, manufactured by High Purity Standards, Inc.) 0.020 mol

[0189] Sc(NO3)3·xH2O(2 <x<6、高纯度化学株式会社制)0.010mol

[0190] [Comparative Example 3]

[0191] In Comparative Example 3, a proton conductor and evaluation particles were prepared in the same manner as in Example 1 except for the following item (1), and the proton conductivity was evaluated.

[0192] (1) The starting materials of the proton conductor were changed to the following materials.

[0193] Ba(NO3)2 (manufactured by Kanto Chemical Co., Ltd.) 0.100 mol

[0194] ZrO(NO3)2·2H2O (manufactured by Kanto Chemical Co., Ltd.) 0.070 mol

[0195] Lu(NO3)3·xH2O(2 <x<6、高纯度化学株式会社制)0.020mol

[0196] Sc(NO3)3·xH2O(2 <x<6、高纯度化学株式会社制)0.010mol

[0197] [Comparative Example 4]

[0198] In Comparative Example 4, a proton conductor and evaluation particles were prepared in the same manner as in Example 1 except for the following item (1), and the proton conductivity was evaluated.

[0199] (1) The starting materials of the proton conductor were changed to the following materials.

[0200] Ba(NO3)2 (manufactured by Kanto Chemical Co., Ltd.) 0.100 mol

[0201] ZrO(NO3)2·2H2O (manufactured by Kanto Chemical Co., Ltd.) 0.070 mol

[0202] Yb(NO3)3·xH2O(2 <x<6、高纯度化学株式会社制)0.020mol

[0203] In(NO3)3·xH2O(2 <x<6、高纯度化学株式会社制)0.010mol

[0204] [Comparative Example 5]

[0205] In Comparative Example 5, a proton conductor and evaluation particles were prepared in the same manner as in Example 1 except for the following item (1), and the proton conductivity was evaluated.

[0206] (1) The starting materials of the proton conductor were changed to the following materials.

[0207] Ba(NO3)2 (manufactured by Kanto Chemical Co., Ltd.) 0.100 mol

[0208] ZrO(NO3)2·2H2O (manufactured by Kanto Chemical Co., Ltd.) 0.060 mol

[0209] Yb(NO3)3·xH2O(2 <x<6、高纯度化学株式会社制)0.020mol

[0210] In(NO3)3·xH2O(2 <x<6、高纯度化学株式会社制)0.020mol

[0211] [Comparative Example 6]

[0212] In Comparative Example 6, a proton conductor and evaluation particles were prepared in the same manner as in Example 1 except for the following item (1), and the proton conductivity was evaluated.

[0213] (1) The starting materials of the proton conductor were changed to the following materials.

[0214] Ba(NO3)2 (manufactured by Kanto Chemical Co., Ltd.) 0.100 mol

[0215] ZrO(NO3)2·2H2O (manufactured by Kanto Chemical Co., Ltd.) 0.070 mol

[0216] Yb(NO3)3·xH2O(2 <x<6、高纯度化学株式会社制)0.020mol

[0217] Lu(NO3)3·xH2O(2 <x<6、高纯度化学株式会社制)0.010mol

[0218] [Comparative Example 7]

[0219] In Comparative Example 7, a proton conductor and evaluation particles were prepared in the same manner as in Example 1 except for the following item (1), and the proton conductivity was evaluated.

[0220] (1) The starting materials of the proton conductor were changed to the following materials.

[0221] Ba(NO3)2 (manufactured by Kanto Chemical Co., Ltd.) 0.100 mol

[0222] ZrO(NO3)2·2H2O (manufactured by Kanto Chemical Co., Ltd.) 0.060 mol

[0223] Yb(NO3)3·xH2O(2 <x<6、高纯度化学株式会社制)0.020mol

[0224] Lu(NO3)3·xH2O(2 <x<6、高纯度化学株式会社制)0.020mol

[0225] [Comparative Example 8]

[0226] In Comparative Example 8, a proton conductor and evaluation particles were prepared in the same manner as in Example 1 except for the following item (1), and the proton conductivity was evaluated.

[0227] (1) The starting materials of the proton conductor were changed to the following materials.

[0228] Ba(NO3)2 (manufactured by Kanto Chemical Co., Ltd.) 0.100 mol

[0229] ZrO(NO3)2·2H2O (manufactured by Kanto Chemical Co., Ltd.) 0.070 mol

[0230] Yb(NO3)3·xH2O(2 <x<6、高纯度化学株式会社制)0.020mol

[0231] Al(NO3)3·xH2O(2 <x<6、高纯度化学株式会社制)0.010mol

[0232] [Comparative Example 9]

[0233] In Comparative Example 9, a proton conductor and evaluation particles were prepared in the same manner as in Example 1 except for the following item (1), and the proton conductivity was evaluated.

[0234] (1) The starting materials of the proton conductor were changed to the following materials.

[0235] Ba(NO3)2 (manufactured by Kanto Chemical Co., Ltd.) 0.100 mol

[0236] ZrO(NO3)2·2H2O (manufactured by Kanto Chemical Co., Ltd.) 0.090 mol

[0237] Sc(NO3)3·xH2O(2 <x<6、高纯度化学株式会社制)0.010mol

[0238] [Comparative Example 10]

[0239] In Comparative Example 10, a proton conductor and evaluation particles were prepared in the same manner as in Example 1 except for the following item (1), and the proton conductivity was evaluated.

[0240] (1) The starting materials of the proton conductor were changed to the following materials.

[0241] Ba(NO3)2 (manufactured by Kanto Chemical Co., Ltd.) 0.100 mol

[0242] ZrO(NO3)2·2H2O (manufactured by Kanto Chemical Co., Ltd.) 0.080 mol

[0243] Sc(NO3)3·xH2O(2 <x<6、高纯度化学株式会社制)0.020mol

[0244] [Comparative Example 11]

[0245] In Comparative Example 11, a proton conductor and evaluation particles were prepared in the same manner as in Example 1 except for the following item (1), and the proton conductivity was evaluated.

[0246] (1) The starting materials of the proton conductor were changed to the following materials.

[0247] Ba(NO3)2 (manufactured by Kanto Chemical Co., Ltd.) 0.100 mol

[0248] ZrO(NO3)2·2H2O (manufactured by Kanto Chemical Co., Ltd.) 0.070 mol

[0249] Sc(NO3)3·xH2O(2 <x<6、高纯度化学株式会社制)0.030mol

[0250] [Comparative Example 12]

[0251] In Comparative Example 12, a proton conductor and evaluation particles were prepared in the same manner as in Example 1 except for the following item (1), and the proton conductivity was evaluated.

[0252] (1) The starting materials of the proton conductor were changed to the following materials.

[0253] Ba(NO3)2 (manufactured by Kanto Chemical Co., Ltd.) 0.100 mol

[0254] ZrO(NO3)2·2H2O (manufactured by Kanto Chemical Co., Ltd.) 0.090 mol

[0255] Yb(NO3)3·xH2O(2 <x<6、高纯度化学株式会社制)0.010mol

[0256] [Comparative Example 13]

[0257] In Comparative Example 13, a proton conductor and evaluation particles were prepared in the same manner as in Example 1 except for the following item (1), and the proton conductivity was evaluated.

[0258] (1) The starting materials of the proton conductor were changed to the following materials.

[0259] Ba(NO3)2 (manufactured by Kanto Chemical Co., Ltd.) 0.100 mol

[0260] ZrO(NO3)2·2H2O (manufactured by Kanto Chemical Co., Ltd.) 0.080 mol

[0261] Yb(NO3)3·xH2O(2 <x<6、高纯度化学株式会社制)0.020mol

[0262] (Evaluation results of proton conductivity)

[0263] Based on Table 1, the results of the proton conductivity of the produced proton conductors will be described.

[0264] First, Example 8 represented by x=0.20, y=0.10 is compared with Comparative Examples 2, 3, 4, 6, and 8 having the same composition ratio of dopants. 0.70 Yb 0.20 Sc 0.10 O 3-δ The highest proton conductivity is shown. In addition, when comparing Example 9 represented by x=0.20 and y=0.20 with Comparative Examples 5 and 7, the BaZr 0.60 Yb 0.20 Sc 0.20 O 3-δ Shows the highest proton conductivity.

[0265] From this, it is expected that Yb and Sc are the best combination of dopants regardless of their composition ratio.

[0266] Next, in BaZr 1-x-y Yb x Sc y O 3-δ Hereinafter, the differences in the various composition ratios shown in Examples 1 to 10 and Comparative Example 1 will be described.

[0267] Among them, only BaZr 0.50 Yb 0.30 Sc 0.20 O 3-δ In Comparative Example 1, cracking occurred during the firing process during the production of evaluation pellets. A high Yb and Sc dopant ratio increases the amount of H₂O dissolved into the material, causing lattice expansion. It is believed that the dense pellets were unable to withstand this expansion, leading to particle cracking.

[0268] That is, increasing the dopant ratio also causes lattice expansion, so cracking is expected to occur in the region where (x+y) ≥ 0.5. On the other hand, the proton conductors of Examples 1 to 10, where (x+y) < 0.5, did not exhibit cracking in the particles.

[0269] In Example 9, Comparative Example 5, and Comparative Example 7, which are indicated by (x+y) ≥ 0.4, cracking of the particles occurred after evaluation. On the other hand, in Examples 1 to 8 and Example 10, which are indicated by (x+y) < 0.4, no cracking occurred after evaluation, suggesting that expansion due to hydration is limited.

[0270] Next, Examples 1 and 2 represented by (x+y)=0.15, Examples 4, 6, and 7 represented by (x+y)=0.25, and Examples 5 and 8 represented by (x+y)=0.30 are compared, respectively.

[0271] In either case, when x ≥ y, the proton conductivity is high at 400° C. and 600° C. Specifically, when the doping amount of Yb is higher than the doping amount of Sc, the proton conductivity is high.

[0272] The proton conductivities of Examples 6 to 10 represented by x≧0.15 are greater than those of Examples 1 to 5 represented by x<0.15.

[0273] In Example 8 represented by x=0.2 and y=0.1, the highest proton conductivity was shown.

[0274] The proton conductor of Comparative Example 10, which was doped only with Sc but not with Yb, had lower proton conductivity at 400°C and 600°C than the proton conductor of Example 3, which had the same dopant ratio (i.e., (x+y) value). Similarly, the proton conductor of Comparative Example 11, which was doped only with Sc but not with Yb, had lower proton conductivity at 400°C and 600°C than the proton conductors of Examples 5 and 8, which had the same dopant ratio (i.e., (x+y) value).

[0275] The proton conductor of Comparative Example 13 doped only with Yb but not with Sc has lower proton conductivity at a low temperature of 400° C. than the proton conductor of Example 3 having the same dopant ratio (ie, the value of (x+y)).

[0276] Table 1

[0277]

[0278] <Electrochemical Unit>

[0279] (Fabrication of Electrochemical Cell)

[0280] Reference Figure 5 , the preparation of the electrolyte membrane and the electrochemical cell using the electrolyte membrane is described.

[0281] (1) Preparation of electrolyte green sheet (see S100 to S102)

[0282] First, an electrolyte ceramic slurry was prepared. The proton conductor (i.e., BaZr 0.70 Yb 0.20 Sc 0.10 O 3-δ ), mix the following materials.

[0283] The proton conductor (BaZr 0.70 Yb 0.20 Sc 0.10 O 3-δ )50g

[0284] Polyvinyl butyral (manufactured by Sekisui Chemical Co., Ltd.) 5g

[0285] 1.25 g of butylbenzyl phthalate (manufactured by Kanto Chemical Co., Ltd.)

[0286] 40g mixed solvent

[0287] The mixed solvent consisted of butyl acetate (20 g, manufactured by Kanto Chemical Co., Ltd.) and 1-butanol (20 g, manufactured by Kanto Chemical Co., Ltd.) In this manner, an electrolyte ceramic slurry was prepared.

[0288] Next, a film made of the electrolyte ceramic slurry was formed on a support sheet made of polyethylene terephthalate film approximately 50 μm thick using a doctor blade method. The resulting slurry film was heated at 80°C to evaporate the solvent. This produced an electrolyte green sheet. The electrolyte green sheet had a thickness of approximately 21 μm.

[0289] (2) Preparation of electrode green sheets (refer to S200 to S202)

[0290] The electrode ceramic slurry is prepared by mixing the following materials.

[0291] The proton conductor (BaZr 0.70 Yb 0.20 Sc 0.10 O 3-δ )10g

[0292] Polyvinyl butyral (manufactured by Sekisui Chemical Co., Ltd.) 5g

[0293] 1.25 g of butylbenzyl phthalate (manufactured by Kanto Chemical Co., Ltd.)

[0294] NiO (manufactured by Sumitomo Metal Mining Co., Ltd.) 40g

[0295] 40g mixed solvent

[0296] The mixed solvent consisted of butyl acetate (20 g, manufactured by Kanto Chemical Co., Ltd.) and 1-butanol (20 g, manufactured by Kanto Chemical Co., Ltd.).

[0297] Next, a film made of the electrode ceramic slurry was formed on a support sheet made of polyethylene terephthalate film approximately 50 μm thick using a doctor blade method. The resulting slurry film had a thickness of approximately 30 μm. The resulting slurry film was heated at 80°C. This produced an electrode green sheet.

[0298] (3) Sheet stacking (see S300 to S303)

[0299] The electrolyte green sheet is cut to obtain a single cut electrolyte green sheet. Next, the polyethylene terephthalate film is peeled from the electrolyte green sheet. The size of the single cut electrolyte green sheet is 140 mm x 140 mm. The electrode green sheet is cut to obtain a single cut electrode green sheet. The size of the single cut electrode green sheet is 140 mm x 140 mm.

[0300] The cut electrode green sheets were stacked to obtain a laminate. The laminate was then hot-pressed at 85°C and 13 MPa. Thus, the first electrode was produced.

[0301] Furthermore, a single cut electrolyte green sheet was stacked on one main surface of the first electrode to obtain a laminate. The laminate was then hot-pressed at 80°C and 13 MPa to obtain a compact.

[0302] The obtained compact was further pressed at a pressure of 50 MPa (manufactured by Sansho Industry Co., Ltd.) to obtain a laminate. The thickness remained almost unchanged at approximately 700 μm.

[0303] The laminate was cut into a size of 20 mm×20 mm.

[0304] Finally, the cut stack was fired in an atmosphere at 1400° C. for 2 hours. In this way, a membrane electrode assembly was produced. The membrane electrode assembly is a joint of the electrolyte membrane and the first electrode.

[0305] (4) Formation of the Second Electrode (See S304 and S305)

[0306] Furthermore, a second electrode is provided on the obtained membrane electrode assembly.

[0307] LSC paste (made by Noritake Co., Ltd., composition La) was applied to one main surface of the membrane electrode assembly where the electrolyte membrane was exposed by screen printing. 0.6 Sr 0.4 CoO 3-δThe diameter of the coated LSC slurry was 10 mm. In this way, a cell precursor was obtained.

[0308] The cell precursor was then fired in an atmosphere at 950°C for 2 hours. This produced an electrochemical cell comprising a first electrode, an electrolyte membrane, and a second electrode. The first electrode served as a fuel electrode, and the second electrode served as an air electrode.

[0309] (Evaluation of electrochemical cell)

[0310] Hydrogen and air were supplied to the electrochemical cell obtained by the above method, and a fuel cell power generation test was carried out.

[0311] The prepared electrochemical cell was placed on a fuel cell holder (manufactured by Chino Co., Ltd.) and placed in an electric furnace. The temperature of the fuel cell holder was raised to 700°C, and the fuel electrode (NiO-BaZr 0.70 Yb 0.20 Sc 0.10 O 3-δ ) was supplied with 20°C humidified hydrogen gas, and 20°C humidified air gas was supplied to the air electrode, and the fuel electrode was reduced for 12 hours. Next, the fuel cell holder was cooled to 600°C and held at 600°C for 1 hour. Electrochemical evaluation was performed using a potentiometer (MODULAB XM ECS, manufactured by AMETEC).

[0312] In the electrochemical evaluation, the voltage of the fuel electrode and the air electrode was swept from the open circuit voltage to 0.4 V at 4 mV / s to obtain the current-voltage curve and the current-output curve. The maximum output obtained was 0.23 W / cm 2 , confirming that current can be extracted as an electrochemical unit.

[0313] Industrial applicability

[0314] The proton conductor of the present disclosure can be suitably used in electrochemical cells and fuel cells.

[0315] Description of Reference Numerals

[0316] 10 Membrane Electrode Assembly

[0317] 11 Electrolyte membrane

[0318] 12 1st electrode

[0319] 13. Second electrode

[0320] 20 electrochemical units

[0321] 30 fuel cell stack

[0322] 1000 Fuel Cell Systems

[0323] 1014 frame

[0324] 1021 Oxidant Gas Supplier

[0325] 1022 Raw Material Feeder

[0326] 1023 Raw gas supply path

[0327] 1024 Oxidant gas supply path

Claims

1. A proton conductor comprising a proton conductor having the chemical formula BaZr (1-x-y) Yb x Sc y O 3-δ A compound represented by Satisfy 0 < x < 0.5, 0 < y < 0.5, 0.15 < (x + y) < 0.4, and 0 < δ < 0.

5.

2. The proton conductor according to claim 1, satisfies the mathematical formula: y ≤ x.

3. The proton conductor according to claim 1 or 2, satisfies the mathematical formula: (x + y) ≥ 0.

20.

4. The proton conductor according to claim 3, satisfies the mathematical formula: (x + y) ≥ 0.

25.

5. The proton conductor according to claim 1 or 2, satisfies the mathematical formula: (x + y) ≤ 0.

35.

6. The proton conductor according to claim 1 or 2, satisfies the mathematical formula: x ≥ 0.

15.

7. The proton conductor according to claim 1 or 2, satisfies the mathematical formula: x = 0.2 and y = 0.

1.

8. An electrolyte membrane comprising the proton conductor according to any one of claims 1 to 7.

9. A membrane electrode assembly comprising: the electrolyte membrane according to claim 8, and a first electrode provided on the first main surface of the electrolyte membrane.

10. An electrochemical cell comprising: the membrane electrode assembly according to claim 9, and a second electrode, wherein the first electrode, the electrolyte membrane, and the second electrode are arranged in sequence.

11. A fuel cell stack comprising a plurality of the electrochemical cells according to claim 10.

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