Ceramic reversible cell, steam electrolysis cell comprising same, fuel cell and ammonia co-electrolysis cell

Abstract

Disclosed is a ceramic reversible cell which contains at least one substance selected from the group consisting of perovskite type metal oxides, hydrates of the perovskite type metal oxides, and hydrides of the perovskite type metal oxides, wherein: the at least one substance selected from the group consisting of perovskite type metal oxides, hydrates of the perovskite type metal oxides, and hydrides of the perovskite type metal oxides contains A (wherein A is at least one element selected from the group consisting of Ba, Sr and Ca), B (wherein B is at least one element selected from the group consisting of Zr, Sn, Ce, Ti and Hf) and M (wherein M is at least one element selected from the group consisting of In, Fe, Cr and Mn) as main metal atoms; and hydride ions are contained therein when equilibrium is reached by bringing dried hydrogen into contact with the ceramic reversible cell, the dried hydrogen satisfying a specific formula and having a moisture content of 20 ppm or less in terms of volume ratio at 500°C to 900°C.

Description

Ceramic reversible cell, and steam electrolysis cell, fuel cell and ammonia co-electrolysis cell including the same

[0001] The present disclosure relates to ceramic reversible cells, and steam electrolysis cells, fuel cells and ammonia co-electrolysis cells containing same.

[0002] Electrochemical cells containing ceramic electrolyte layers (hereinafter referred to as "ceramic reversible cells") are one of the efficient devices for producing hydrogen from renewable electricity, for example, when used as steam electrolysis cells. Ceramic reversible cells are also useful as fuel cells or ammonia co-electrolysis cells.

[0003] Patent Document 1 discloses an ion conductor that is a perovskite oxide essentially consisting of Ba, Zr, Ce, and O and that conducts substantially only protons, and a ceramic reversible cell using the same. Non-Patent Document 1 discloses a ceramic reversible cell using a proton conductor.

[0004] Japanese Patent Application Laid-Open No. 2001-307546

[0005] “Steam electrolysis by solid oxide electrolysis cells (SOECs) with proton-conducting oxides”, Chem. Soc. Rev. , 2014, 43, 8255-8270

[0006] However, the ceramic reversible cell disclosed in Patent Document 1 and the like does not have sufficient characteristics, and further improvement is required.

[0007] The present disclosure has been made in light of these circumstances, and one of its objectives is to provide a ceramic reversible cell that can exhibit better characteristics than those of the prior art (for example, a high electrolysis current density at 600°C and 1.3 V as a steam electrolysis cell, a high output at 600°C as a fuel cell, and a Faraday efficiency of ammonia at 600°C of 0.1% or more as an ammonia co-electrolysis cell).

[0008] A first aspect of the present invention is a ceramic reversible cell comprising one or more selected from the group consisting of perovskite metal oxides, hydrates of the perovskite metal oxides, and hydrides of the perovskite metal oxides, wherein the one or more selected from the group consisting of perovskite metal oxides, hydrates of the perovskite metal oxides, and hydrides of the perovskite metal oxides contain A (wherein A is one or more selected from the group consisting of Ba, Sr, and Ca), B (wherein B is one or more selected from the group consisting of Zr, Sn, Ce, Ti, and Hf), and M (wherein M is one or more selected from the group consisting of In, Fe, Cr, and Mn) as main metal atoms, and the ceramic reversible cell satisfies the following formula (1), and contains hydride ions when brought into equilibrium at 500°C to 900°C and brought into contact with dry hydrogen having a water content of 20 ppm or less by volume: [A]:[B]:[M]=1:a(1−x):ax (1) In formula (1), [A], [B], and [M] respectively represent the contents of A, B, and M expressed in mol%, and satisfy the relationships of 0.90≦a≦1.10 and 0.3≦x<1.0.

[0009] A second aspect of the present invention is the ceramic reversible cell according to the first aspect, wherein at least one selected from the group consisting of the perovskite metal oxide, the hydrate of the perovskite metal oxide, and the hydride of the perovskite metal oxide has a layer containing hydride ions on the fuel electrode side, and does not have a layer containing hydride ions on the air electrode side of the layer containing hydride ions.

[0010] A third aspect of the present invention is the ceramic reversible cell according to the first or second aspect, wherein at least one selected from the group consisting of the perovskite metal oxide, the perovskite metal oxide hydrate, and the perovskite metal oxide hydride further satisfies the following formula (3) when brought into equilibrium at 500°C to 900°C in contact with dry hydrogen having a water content of 20 ppm or less by volume: 1.5<[O] / [A]≦2.30 (3) In formula (3), [O] represents the content, in mol %, of oxygen atoms present at oxygen sites in the perovskite structure, obtained from the Rietveld analysis of the neutron diffraction pattern.

[0011] A fourth aspect of the present invention is the ceramic reversible cell according to any one of the first to third aspects, having: a first layer containing one or more selected from the group consisting of the perovskite metal oxide, a hydrate of the perovskite metal oxide, and a hydride of the perovskite metal oxide; and a second layer containing one or more selected from the group consisting of the perovskite metal oxide, a hydrate of the perovskite metal oxide, and a hydride of the perovskite metal oxide, and one or more selected from the group consisting of Ni, Fe, Co, Pd, Cu, and Ru.

[0012] A fifth aspect of the present invention is the ceramic reversible cell according to the fourth aspect, which comprises the second layer, the first layer, and a third layer containing a conductive oxide, in this order.

[0013] A sixth aspect of the present invention is a steam electrolysis cell including the ceramic reversible cell according to any one of the first to fifth aspects.

[0014] A seventh aspect of the present invention is a fuel cell including the ceramic reversible cell according to any one of the first to fifth aspects.

[0015] Aspect 8 of the present invention is an ammonia co-electrolysis cell comprising the ceramic reversible cell according to any one of Aspects 1 to 5.

[0016] According to embodiments of the present invention, it is possible to provide a ceramic reversible cell, as well as a steam electrolysis cell, a fuel cell, and an ammonia co-electrolysis cell including the same, which can exhibit better performance than the prior art.

[0017] p Ｈ２Ｏ 1 is a schematic diagram of the defect concentration of a conventional proton-conducting perovskite oxide when the p Ｈ２Ｏ 1A and 1C. Ｈ２Ｏ 1 is a schematic diagram of the concentration of each defect in a conventional proton-conducting perovskite oxide when the p in the electrolyte is relatively low. Ｈ２ and p Ｈ２Ｏ 1 is a schematic diagram of the distribution (dashed line) of defects in the vicinity of the air electrode of a steam electrolysis cell having a conventional proton-conducting perovskite metal oxide or the like; FIG. 2 is a schematic diagram of the concentration of defects in the vicinity of the fuel electrode of a steam electrolysis cell having a conventional proton-conducting perovskite metal oxide or the like; FIG. 3 is a schematic diagram of a steam electrolysis cell including a perovskite metal oxide or the like according to an embodiment of the present invention, and the distribution (dashed line) of p in the perovskite metal oxide; Ｈ２ and p Ｈ２Ｏ FIG. 1 shows a schematic diagram of the distribution (broken line) of defects in the vicinity of the air electrode of a steam electrolysis cell including a perovskite metal oxide or the like according to an embodiment of the present invention. FIG. 2 shows a schematic diagram of the concentration of defects in the vicinity of the fuel electrode of a steam electrolysis cell including a perovskite metal oxide or the like according to an embodiment of the present invention. FIG. 3 shows a schematic diagram of the concentration of defects inside the perovskite metal oxide bulk of a steam electrolysis cell including a perovskite metal oxide or the like according to an embodiment of the present invention. ５５ 1 shows the NRD pattern and Rietveld calculated profile of Sample 2 (corresponding to BZI in a comparative ceramic reversible cell). ５５1 shows the NRD pattern and Rietveld calculated profile of Sample 1' (corresponding to HBZI in the ceramic reversible cell of the example). 2 shows the NRD pattern and Rietveld calculated profile of Sample 3. 3 shows the NRD pattern and Rietveld calculated profile of Sample 4. 4 shows the NRD pattern and Rietveld calculated profile of Sample 5. 5 shows the NRD pattern and Rietveld calculated profile of Sample 6. 6 shows the NRD pattern and Rietveld calculated profile of Sample 1' (corresponding to HBZI in the ceramic reversible cell of the example). ５５ 1 shows the relationship between hydrogen partial pressure and hydrogen absorption amount at each temperature for the cell of the comparative example (corresponding to v ). 2 shows the current-voltage (IV) curve for water electrolysis of the cell of the comparative example. 3 shows the current-voltage (IV) curve for water electrolysis of the cell of the example. 4 shows the AC impedance spectrum for the cell of the comparative example. 5 shows the AC impedance spectrum for the cell of the example. 6 shows the cell voltage, hydrogen generation rate (v ) and hydrogen absorption rate (v ) for water electrolysis of the cell of the comparative example (corresponding to v ). ｍｅａｓ ), and Faraday efficiency (η). When constant current steam electrolysis was performed for 4 hours using the cell of the example, the cell voltage, hydrogen generation rate (v ｍｅａｓ ), and Faraday efficiency (η). The graph shows the voltage (solid line, vertical left axis) and output curve (dashed line, vertical right axis) versus current (horizontal axis) of a cell (fuel cell) of a comparative example. The graph shows the voltage (solid line, vertical left axis) and output curve (dashed line, vertical right axis) versus current (horizontal axis) of a cell (fuel cell) of an example. The graph shows the AC impedance spectrum of a cell (fuel cell) of a comparative example. The graph shows the AC impedance spectrum of a cell (fuel cell) of an example. The graph shows a cross-sectional SEM image of a cell of a comparative example after steam electrolysis. The graph shows a cross-sectional SEM image of a cell of an example after steam electrolysis. The graph shows a cross-sectional SEM image (enlarged image between the first layer 102 and the third layer 104) of a cell of an example after steam electrolysis. The graph shows a surface SEM image of the first layer 102 of a cell of an example after steam electrolysis. The graph shows the N of a cell of an example. ２ -H ２ The results of co-electrolysis (voltage change) of the N2O2 cell of the example are shown. ２ -H ２ O co-electrolysis results (H in MASS spectrum ２ , N ２ and N.H. ３1 shows the change in signal intensity of the cell No. 14. 2 shows an optical microscope image of the side surface of the cell No. 13. 3 shows an optical microscope image of the side surface of the cell No. 12. 4 shows an optical microscope image of the side surface of the cell No. 11. 5 shows the electric field current-voltage curves of the cells No. 11 to 14. 6 shows the cell voltage (V) and hydrogen generation rate (V) when the cell No. 14 was subjected to constant current electrolysis. Ｈ２ ), and Faraday efficiency. The cell voltage (V) and hydrogen generation rate (V) of the cell of sample No. 12 when constant current electrolysis was performed are shown. Ｈ２ ), and Faraday efficiency. AC impedance spectra of the cells of Samples 11 to 14 are shown. μXAFS measurement results of the cell of Sample 12 are shown. μXAFS measurement results of the cell of Sample 12 are shown. NRD pattern and Rietveld calculated profile of the blackened layer of Sample 12 are shown.

[0018] The present inventors have investigated from various angles in order to realize a ceramic reversible cell that can exhibit better characteristics than the prior art. As a result, they have found a ceramic reversible cell that contains a predetermined metal oxide and / or its hydrate and / or its hydride having a perovskite structure, and that generates hydride ions (H － ) (confirmed, for example, by having hydrogen atoms present at one or more positions selected from the group consisting of oxygen positions (oxygen sites) and

[100] face-centered positions in the perovskite structure), it has been found that a ceramic reversible cell can be obtained that can exhibit better characteristics than conventional techniques (for example, a high electrolysis current density at 600°C and 1.3V as a steam electrolysis cell, a high output at 600°C as a fuel cell, and a Faraday efficiency of ammonia at 600°C of 0.1% or more as an ammonia co-electrolysis cell). This is because the hydrogen atoms present at these positions are converted into hydride ions (H － ) is known to be a proton-conducting material. In addition, the above metal oxides and the like inherently have proton conductivity, and in the part that comes into contact with dry hydrogen at high temperature, H － was introduced and H －It is believed that the conductivity of the material makes it possible to suppress hole or electron leakage, thereby demonstrating better characteristics than the prior art. The mechanism by which hole or electron leakage can be suppressed is believed to be as follows.

[0019] Generally, in the proton-conducting metal oxide and / or its hydrate and / or its hydrate (hereinafter sometimes referred to as "metal oxide, etc.") disclosed in Patent Document 1, H ２ -H ２ In an O atmosphere, the defect equilibria of the following formulas (F1) to (F4) are established.

[0020]

[0021] ABO as disclosed in U.S. Pat. ３ Perovskite metal oxide (A: Ba ２＋ etc., B: Zr ４＋ etc.), and a part of the tetravalent cations B at the B site is replaced by trivalent acceptor cations M(In ３＋ Proton-conducting oxide AB substituted with １－ｘ M ｘ O ３－ｘ／２ For the above, when the defect equilibrium of the above formulas (F1) to (F4) holds, the following formula (F5) holds due to the electroneutrality condition for defects.

[0022]

[0023]

[0024] 1A to 1C show a conventional proton-conducting perovskite metal oxide AB as disclosed in Patent Document 1. １－ｘ M ｘ O ３－ｘ／２ The defect concentration of each defect, such as Ｈ２ / p Ｈ２Ｏ 1A shows the logarithmic representation of the Ｈ２Ｏ 1C shows the defect concentrations when p Ｈ２Ｏ 1B shows the defect concentrations when p Ｈ２Ｏ indicates the defect concentration when it is approximately halfway between Figures 1A and 1C. The following can be seen from Figures 1A to 1C.

[0025]

[0026] The above mechanism does not limit the technical scope of the embodiment of the present invention. Each requirement defined by the embodiment of the present invention will be described in detail below.

[0027] A ceramic reversible cell according to an embodiment of the present invention is a ceramic reversible cell comprising one or more selected from the group consisting of perovskite metal oxides, hydrates of the perovskite metal oxides, and hydrides of the perovskite metal oxides, wherein the one or more selected from the group consisting of the perovskite metal oxides, hydrates of the perovskite metal oxides, and hydrides of the perovskite metal oxides contain A (wherein A is one or more selected from the group consisting of Ba, Sr, and Ca), B (wherein B is one or more selected from the group consisting of Zr, Sn, Ce, Ti, and Hf), and M (wherein M is one or more selected from the group consisting of In, Fe, Cr, and Mn) as main metal atoms, and satisfies the following formula (1), and contains hydride ions when brought into equilibrium at 500°C to 900°C and brought into contact with dry hydrogen having a water content of 20 ppm or less by volume: [A]:[B]:[M]:=1:a(1-x):ax (1) In formula (1), [A], [B], and [M] respectively represent the contents of A, B, and M expressed in mol %, and satisfy the relationships 0.90≦a≦1.10 and 0.3≦x<1.0. As a result, a ceramic reversible cell can be obtained that exhibits better characteristics than conventional techniques (e.g., as a steam electrolysis cell, a high electrolysis current density at 600°C and 1.3V; as a fuel cell, a high output at 600°C; as an ammonia co-electrolysis cell, a Faraday efficiency of ammonia at 600°C of 0.1% or more). As described above, one factor behind this is thought to be the ability to suppress leakage current compared to conventional techniques. The Faraday efficiency of ammonia at 600°C is preferably 1% or more, more preferably 5% or more. The metal oxide is referred to as "AB ａ（１－ｘ） M ａｘ O ３－δ" may also be written.

[0028] The ceramic reversible cell according to an embodiment of the present invention has the general formula ABO ３ The metal oxide and / or its hydrate and / or its hydride having a perovskite structure that can be represented by the formula: The perovskite structure may be a cubic, hexagonal, orthorhombic, monoclinic, tetragonal, or the like, and is not particularly limited, but a cubic perovskite is preferred because it can be stable. Whether or not the material contains such a perovskite structure can be confirmed by obtaining an electron diffraction pattern using a field emission transmission electron microscope (FE-TEM), for example.

[0029] The perovskite-type metal oxides and the like contain the above-mentioned A, B, and M as main metal atoms, and may satisfy, for example, the following formula (4): ([A] + [B] + [M]) / [X] ≧ 0.75 (4) In formula (4), X represents all elements except oxygen and hydrogen, and [A], [B], [M], and [X] represent the contents of A, B, M, and X, respectively, expressed in mole percent. The left side of formula (4) increases, for example, when the amount of impurity elements is small. From the viewpoint of reducing impurities, the left side of formula (4) is preferably 0.90 or more, and more preferably 0.95 or more. In addition, it is preferable that the following formula (5) be satisfied: ([A] + [B] + [M]) / [X ２ ] ≧ 0.50 (5) where X ２ represents all elements except oxygen. The left side of formula (5) also increases, for example, when the amount of impurity elements is small. From the viewpoint of reducing the amount of impurities, it is more preferable that the left side of formula (5) is 0.55 or more.

[0030] In formula (1), A may be a divalent cation, B may be a tetravalent cation, and M may be a trivalent or lower cation. By replacing a portion of B with M, oxygen deficiency occurs, and proton conductivity can be exhibited. －From the viewpoint that it is easy to introduce (i.e., it is easy to satisfy formula (2)), A is any one or more selected from the group consisting of Ba, Sr and Ca, and B is any one or more selected from the group consisting of Zr, Sn, Ce, Ti and Hf. From the viewpoint that it is easy to maintain the cubic perovskite structure, A is preferably any one or more selected from the group consisting of Ba and Sr. As M, H － From the viewpoint of facilitating the incorporation of H and of providing corrosion resistance in the dry hydrogen treatment described later, the element is at least one selected from the group consisting of In, Fe, Cr, and Mn. － To introduce M, a certain amount of oxygen deficiency may be necessary, and the substitution amount x of B by M is set to 0.3 or more, preferably 0.4 or more. On the other hand, in relation to the structural stability of the perovskite metal oxide, x is set to less than 1, preferably 0.8 or less.

[0031] In the embodiment of the present invention, whether or not formula (1) is satisfied can be determined by, for example, general composition analysis (FE-TEM / EDS, etc.). Note that elements other than the elements specified above (e.g., impurities) may also be detected in the composition analysis, but it is sufficient that formula (1) is satisfied. Furthermore, although measurement errors may occur in the composition analysis, the a value is set taking this into consideration, and it is sufficient that 0.90≦a≦1.10.

[0032] The perovskite-type metal oxides contained in the ceramic reversible cell according to the embodiment of the present invention can exhibit proton conductivity under normal circumstances. However, when they are brought into contact with dry hydrogen having a water content of 20 ppm or less by volume at 500°C to 900°C and reach an equilibrium state (i.e., the composition change becomes constant), they convert hydride ions (H － ) was introduced, and H － and so H － It becomes conductive. － Whether or not the compound contains [H] can be confirmed by checking whether or not any one or more selected from the group consisting of the following (a) to (c) is satisfied: (a) The following formula (2) is satisfied; －] / [A]≧0.05 (2) (In formula (2), H － indicates hydrogen atoms present at one or more positions selected from the group consisting of oxygen positions and

[100] face-centered positions of the perovskite structure obtained from the Rietveld analysis of the neutron diffraction pattern, and [A] and [H － ] are A and H in mole percent, respectively. － (b) the portion is blackened (darkened) compared to the portion not contacted with dry hydrogen; and (c) the position at which the normalized absorbance is 0.5 in a μXAFS spectrum measured with a synchrotron X-ray microprobe is shifted to lower energy by 0.2 eV or more compared to the portion not contacted with dry hydrogen.

[0033] In the formula (2) of the above requirement (a), H － may be, for example, a hydrogen atom or a deuterium atom present at a predetermined position. － was introduced (H － The left side of the formula (2) is preferably 0.15 or more, and more preferably 0.30 or more. When the left side of the formula (2) is less than 0.05, H － is small, and sufficient H － Since it is believed that the material does not exhibit conductivity, in this specification, H － was introduced (H － The portion that is not in contact with dry hydrogen does not satisfy formula (2) and can maintain proton conductivity. In the portion that is not in contact with dry hydrogen, the left side of formula (2) is less than 0.05, preferably 0.03 or less, more preferably 0.01 or less, and most preferably 0.00.

[0034] Regarding the above requirement (b), the portion that has been contacted with dry hydrogen (i.e., H － The part or layer containing the oxygen is more deficient and has H －Therefore, the part that has been in contact with dry hydrogen turns black compared to the part that has not been in contact with dry hydrogen, and the part that has been in contact with dry hydrogen is － was introduced (i.e., H － It can be determined that this includes

[0035] Regarding the above requirement (c), the portion that has been contacted with dry hydrogen (i.e., H － The part or layer containing the oxygen is more deficient and has H － By introducing H, the μXAFS spectrum measured by the synchrotron X-ray microprobe is shifted to the lower energy side, specifically, the position where the standardized absorbance is 0.5 is shifted to the lower energy side by 0.2 eV or more. Therefore, the position of the dry hydrogen contacted portion is shifted to the lower energy side by 0.2 eV or more compared to the portion not contacted with dry hydrogen, and therefore, H is introduced to the dry hydrogen contacted portion. － was introduced (i.e., H － It can be determined that this includes

[0036] The dry hydrogen to be contacted may have a water content within the above range. ２ and a mixed gas of an inert gas such as Ar (H ２ / Ar) may be used, and the hydrogen concentration may be 10% by volume or more. The hydrogen may be, for example, light hydrogen or heavy hydrogen. The water relating to the "moisture content" may be, for example, light water or heavy water (D ２ If the temperature range and water content are not satisfied, even if the perovskite metal oxide satisfies the above formula (1), H － In this case, the dry hydrogen may not be sufficiently introduced, and one or more of the above conditions (a) to (c) may not be satisfied. In order to bring the dry hydrogen into contact with the dry hydrogen and reach an equilibrium state, the contact time may be long enough; for example, the equilibrium state can be considered to have been reached by contacting the dry hydrogen for 10 hours or more.

[0037] By contacting with dry hydrogen, the perovskite metal oxide or the like contained in the ceramic reversible cell according to the embodiment of the present invention has a portion (or layer) containing hydride ions. The side contacted with dry hydrogen has hydride ion conductivity and can be used as the fuel electrode and / or electrolyte layer on the fuel electrode side. The side not contacted with dry hydrogen maintains its original proton conductivity and can be used as the air electrode and / or electrolyte layer on the air electrode side. In a preferred embodiment of the ceramic reversible cell of the present invention, the perovskite metal oxide or the like has a layer containing hydride ions (hereinafter referred to as "hydride ions (H － ) conducting layer”), and no layer containing hydride ions is present on the other side (air electrode side) of the layer containing hydride ions (i.e., the other side is hereinafter referred to as “proton (H ＋ Such a ceramic reversible cell is － Conductive layer and H ＋ Since the cell has a conductive layer, it is also called a bipolar conduction cell. － The "conductive layer" is a layer that satisfies one or more of the above (a) to (c). － The "conductive layer" in (a) above may be a layer that satisfies the formula (2) above, and in (b) above, may be a layer that satisfies the formula (2) above. ＋ It may be a layer that is blackened (darkened) compared to the conductive layer, and in (c) above, H ＋ It may be a layer in which the position where the normalized absorbance of the μXAFS spectrum measured by a synchrotron X-ray microprobe becomes 0.5 is shifted to the lower energy side by 0.2 eV or more compared to the conductive layer. ＋ The term "conductive layer" refers to a layer that does not satisfy the above (a) to (c). ＋ In the above (a), the "conductive layer" may be a layer that does not satisfy the above formula (2) (i.e., the left side of the above formula (2) is less than 0.05), and in the above (b), H － It may be a layer that is white (light color) compared to the conductive layer, and in (c) above, H －The layer may be one in which the position where the normalized absorbance of the μXAFS spectrum measured by a synchrotron X-ray microprobe becomes 0.5 is shifted to the higher energy side by 0.2 eV or more compared to the conductive layer. ＋ In the "conductive layer" above (a), the left side of the formula (2) above is preferably 0.03 or less, more preferably 0.01 or less, and most preferably 0.00.

[0038] It is preferable that the ceramic reversible cell according to the embodiment of the present invention further satisfies the following formula (3) when it is brought into equilibrium at 500°C to 900°C and brought into contact with dry hydrogen having a water content of 20 ppm or less by volume: 1.5<[O] / [A]≦2.30 (3) In formula (3), [O] represents the content, expressed in mole percent, of oxygen atoms present at oxygen positions in the perovskite structure obtained from the Rietveld analysis of the neutron diffraction pattern. By satisfying formula (3), a certain number or more of oxygen vacancies are present, forming a percolation path for oxygen vacancies, and H － In a preferred embodiment of the present invention, the ratio [O] / [A] in formula (3) is preferably greater than 1.5 and not greater than 2.25. － The conductive layer satisfies the above formula (3) and ＋ It is preferable that the conductive layer does not satisfy the above formula (3) (for example, 2.30<[O] / [A]<3.00).

[0039] A ceramic reversible cell according to an embodiment of the present invention includes the perovskite metal oxide or the like, and can use, for example, one surface that contacts the dry hydrogen as an anode and the other surface opposite the anode as a cathode. That is, in one embodiment of the present invention, the ceramic reversible cell may be a single layer containing the perovskite metal oxide or the like. In one embodiment of the present invention, the single layer of the ceramic reversible cell may contain 50 area % or more, 75 area % or more, or 90 area % or more of the perovskite metal oxide or the like in a cross section parallel to the layer thickness direction. Furthermore, in the single layer, the perovskite metal oxide or the like may have a continuous portion from the anode to the cathode.

[0040] A ceramic reversible cell may include multiple layers without departing from the scope of the present invention. For example, a ceramic reversible cell according to an embodiment of the present invention may have a first layer containing the perovskite metal oxide or the like, and a second layer (i.e., a cermet electrode layer) containing the perovskite metal oxide or the like and a metal. The metal may be one or more selected from the group consisting of Ni, Fe, Co, Pd, Cu, and Ru, preferably one or more selected from the group consisting of Ni, Fe, and Ru. The second layer may be porous to increase the area where an electrode reaction occurs. For example, a ceramic reversible cell according to an embodiment of the present invention may have a first layer (also referred to as an electrolyte layer) containing the perovskite metal oxide or the like, and a second layer consisting of a known anode layer (e.g., a Pt layer). The thicknesses of the first and second layers are not particularly limited. The first layer may have a thickness similar to that of a known electrolyte layer, and the second layer may have a thickness similar to that of a known anode layer. The methods for producing the first and second layers are not particularly limited, and the first layer can be produced, for example, by a method similar to that for a known electrolyte layer, and the second layer can be produced, for example, by a method similar to that for a known fuel electrode layer. The first and second layers may be in direct contact with each other, but they may not be in contact with each other; that is, another layer may be present between the first and second layers.

[0041] The ceramic reversible cell according to the embodiment of the present invention can be used, for example, by using the second layer as the fuel electrode and the first layer as the air electrode, and by contacting the second layer with the above-mentioned dry hydrogen at a high temperature. Note that the perovskite-type metal oxide or the like contained in the second layer can satisfy the above formula (2) regardless of the presence or absence of a metal (such as Ni) in the second layer by contacting the second layer with the above-mentioned dry hydrogen at a high temperature and reaching an equilibrium state.

[0042] Furthermore, the ceramic reversible cell according to the embodiment of the present invention may have the second layer, the first layer, and a third layer containing a conductive oxide, in this order. The third layer may be porous to increase the area where the electrode reaction occurs. The conductive oxide may be a dual-conductive material (La) that conducts oxide ions and electrons (holes). １－ｘ Sr ｘ CoO ３－δ(LSC), LaSrCoO ４＋δ (LSC4), LaNiO ３－δ (LNO), La １－ｘ Sr ｘ Co １－ｙ Fe ｙ O ３－δ (LSCF), La １－ｘ Sr ｘ MnO ３－δ (LSM), Sm ｘ Sr １－ｘ CoO ３－δ (SSC), or triple conducting materials (BaCo １－ｘ－ｙ－ｚ Fe ｘ Zr ｙ Y ｚ O ３－δ (BCFZY), BaPr １－ｘ Y ｘ O ３－δ (BPY), PrNi １－ｘ Co ｘ O ３－δ (PNC), PrBa １－ｘ Sr ｘ Co ２－ｙ Fe ｙ O ５＋δ (PBSCF), NdBa １－ｘ Sr ｘ Co ２－ｙ Fe ｙ O ５＋δ (NBSCF), PrBa １－ｘ Ca ｘ Co ２ O ５＋δ (PBCC), Ba １－ｘ Gd ０．８ La ０．２＋ｘ Co ２ O ６－δ(BGLC) or the like) can be suitably used. To obtain a ceramic reversible cell with better characteristics, the third layer preferably contains one or more materials selected from the group consisting of dual-conductivity materials and triple-conductivity materials, and more preferably contains one or more materials selected from triple-conductivity materials. The ceramic reversible cell according to the embodiment of the present invention can be used, for example, by using the second layer as the fuel electrode and the third layer as the air electrode, and by contacting the second layer with dry hydrogen at high temperatures. The thickness of the third layer is not particularly limited, and the third layer may have a thickness similar to that of a known air electrode layer. The manufacturing method of the third layer is not particularly limited, and the third layer can be manufactured, for example, by a method similar to that of a known air electrode layer. The third layer and the first layer may be in direct contact with each other, or may not be in direct contact with each other; that is, another layer may be present between the third layer and the first layer.

[0043] Furthermore, the ceramic reversible cell according to the embodiment of the present invention may have a fourth layer, which is an interface functional layer, between the first layer and the third layer. The fourth layer may contain a second conductive oxide different from the conductive oxide contained in the third layer. The fourth layer may contain a second perovskite metal oxide and / or a hydrate thereof, which satisfies the following formula (6) and either one of the following formulas (7a) and (8a), and when the following formula (7a) is satisfied, the following formula (7b) may also be satisfied, and when the following formula (8a) is satisfied, the following formula (8b) may also be satisfied. ([Ba] + [R １ ] + [R ２ ]+[Fe]) / [A １ ]≧0.75...(6) [Ba]+[R １ ]≦[Fe]+[M １ ]+[M ２ ]...(7a) [Ba]:[R １ ]:[R ２ ]:[Fe]:[M １ ]:[M ２ ] = (1 - x ａ -y ａ ): x ａ :y ａ : c (1-l ａ -m ａ ): cl ａ :cmａ ...(7b) [Ba]+[R １ ]>[Fe]+[M １ ]+[M ２ ]...(8a) [Ba]:[R １ ]:[Fe]:[M １ ]:[M ２ ]:[R ２ ] = (1 - x ｂ ): x ｂ : c (1-l ｂ -m ｂ -n ｂ ): cl ｂ :cm ｂ :cn ｂ ...(8b) In formulas (6) to (8b), R １ is at least one selected from the group consisting of La, Ce, Pr, Nd, Pm, Sm, Eu, and Gd, and R ２ is at least one selected from the group consisting of Sc, Y, Tb, Dy, Ho, Er, Tm, Yb and Lu, and A １ are all elements except oxygen and hydrogen, and M １ is at least one selected from the group consisting of Li, Na, Mg, Al, Ca, Cu, Zn, Ga, Ag, Cd, In, Hg, and Tl, and M ２ is at least one metal selected from the group consisting of metals in periods 4 to 6 and groups 4 to 10 of the periodic table (excluding Fe), [Ba], [R １ ], [R ２ ], [Fe], [A １ ], [M １ ] and [M ２ ] are Ba and R in mole percent, respectively. １ , R ２ ,Fe,A. １ , M １ and M ２ and 0≦(x ａ +y ａ )<1.0, 0≦(l ａ +m ａ ) ≦0.3, 0 ≦ m ａ <0.3, 0.90≦c≦1.10, 0≦x ｂ <1.0, 0≦(l ｂ +m ｂ +nｂ ) ≦0.3, 0 ≦ m ｂ <0.3.

[0044] The fourth layer is a compound of the general formula ABO ３ The perovskite structure may include a metal oxide and / or a hydrate thereof having a perovskite structure represented by the formula (1). The perovskite structure may be a cubic, hexagonal, orthorhombic, monoclinic, tetragonal, or the like, and is not particularly limited, but a cubic perovskite may be stable and is preferred. Whether or not the perovskite structure is contained can be confirmed by obtaining an electron diffraction pattern using a field emission transmission electron microscope (FE-TEM), for example.

[0045] In one embodiment, the fourth layer may contain 50 area % or more, 75 area % or more, or 90 area % or more of the second perovskite metal oxide and / or hydrate thereof in a cross section parallel to the stacking direction. The fourth layer may also have a portion where the second perovskite metal oxide and / or hydrate thereof is continuous from one surface to the other in the stacking direction. This can be confirmed by cross-sectional TEM observation.

[0046] The left side of formula (6) increases when the amount of impurity elements is small, for example. From the viewpoint of reducing the amount of impurities, it is preferable that the left side of formula (6) is 0.80 or more. It is also preferable that the following formula (9) is satisfied: ([Ba] + [R １ ]+[R ２ ]+[Fe]) / [A ２ ] ≧ 0.60 (9) where A ２ represents all elements except oxygen. The left side of formula (9) also increases, for example, when the amount of impurity elements is small. From the viewpoint of reducing the amount of impurities, it is more preferable that the left side of formula (9) is 0.65 or more.

[0047] When formula (7a) is satisfied (i.e., Ba １－ｘａ－ｙａ R １ ｘａ R ２ ｙａ Fec(1-la-ma)M １ ｃｌａ M ２ ｃｍａ O ３－δIn the case of the layer), Ba forms a divalent cation, and R forms a trivalent cation. １ and / or R ２ By substituting with, unstable Fe ４＋ Fe ３＋ From the viewpoint of stabilizing the perovskite structure, it is preferable that 0<(x ａ +y ａ ) < 1.0, and more preferably 0.5 ≦ (x ａ +y ａ ) < 1.0, and more preferably 0.7 ≦ (x ａ +y ａ ) < 1.0. Similarly, when formula (8a) is satisfied (i.e., Ba １－ｘｂ R １ ｘｂ Fec(1-lb-mb-nb)M １ ｃｌｂ M ２ ｃｍｂ R ２ ｃｎｂ O ３－δ In the case of the layer), Ba forms a divalent cation, and R forms a trivalent cation. １ By substituting with, unstable Fe ４＋ Fe ３＋ From the viewpoint of stabilizing the perovskite structure, it is preferable that 0<x ｂ <1.0, and more preferably 0.5≦x ｂ <1.0, and more preferably 0.7≦x ｂ <1.0. １ By using one or more elements selected from the group consisting of La, Ce, Pr, Nd, Pm, and Sm, the perovskite structure can be made more stable. On the other hand, by decreasing the amount of substitution and increasing the amount of Ba, more water molecules are adsorbed, and proton conductivity can be improved. From the viewpoint of water adsorption, etc., when formula (7a) is satisfied, it is preferable that 0≦(x ａ +y ａ )≦0.5, and more preferably 0≦(x ａ +y ａSimilarly, when formula (8a) is satisfied, it is preferable that 0≦x ｂ ≦0.5, more preferably 0≦x ｂ ≦0.3.

[0048] When formula (7a) is satisfied (i.e., Ba １－ｘａ－ｙａ R １ ｘａ R ２ ｙａ Fec(1-la-ma)M １ ｃｌａ M ２ ｃｍａ O ３－δ layer), Fe is replaced with M １ (one or more selected from the group consisting of Li, Na, Mg, Al, Ca, Cu, Zn, Ga, Ag, Cd, In, Hg and Tl) or M １ and M ２ (one or more metals selected from the group consisting of metals in periods 4 to 6 and groups 4 to 10 of the periodic table). Similarly, when formula (8a) is satisfied (i.e., Ba １－ｘｂ R １ ｘｂ Fec(1-lb-mb-nb)M １ ｃｌｂ M ２ ｃｍｂ R ２ ｃｎｂ O ３－δ layer), Fe is replaced with M １ , M ２ and R ２ can be substituted with one or more selected from the group consisting of (provided that M ２ (It cannot be replaced by only M. １ and R ２ has a smaller ionic valence than Fe. Therefore, Fe is １ and / or R ２ By substituting Ba １－ｘａ－ｙａ R １ ｘａ R ２ ｙａ Fec(1-la-ma)M １ ｃｌａ M ２ ｃｍａ O ３－δ layer or Ba １－ｘｂ R１ ｘｂ Fec(1-lb-mb-nb)M １ ｃｌｂ M ２ ｃｍｂ R ２ ｃｎｂ O ３－δ Oxygen vacancies may occur in the layer. １ and / or R ２ In addition, M, which has an ionic valence similar to Fe, ２ may be substituted for Fe.

[0049] In order to improve the cell performance, it is necessary to keep the amount of Fe substitution low to some extent. ａ +m ａ ) ≦0.3, 0 ≦ m ａ <0.3, 0≦(l ｂ +m ｂ +n ｂ ) ≦0.3, 0 ≦ m ａ It is preferable that the ratio is <0.3. More preferably, the ratio is 0.05≦(l ａ +m ａ ) ≦0.25, 0 ≦ m ａ <0.25, 0.05≦(l ｂ +m ｂ +n ｂ ) ≦0.25, 0 ≦ m ｂ <0.25.

[0050] M １ is preferably at least one element selected from the group consisting of Li, Mg, Al, Cu, Zn, Ga, Cd, In and Tl, since this can stabilize the perovskite structure in terms of ionic radius. １ is more preferably at least one element selected from the group consisting of Mg, Al, Cu, Zn and Ga, which can make the perovskite structure more stable in terms of ionic radius.

[0051] M ２ is preferably at least one selected from Ti, V, Cr and metals in periods 5 to 6 and groups 4 to 10 of the periodic table, since this can stabilize the perovskite structure in terms of ionic radius.

[0052] In the embodiments of the present invention, whether or not formulas (6) to (8b) are satisfied can be determined, for example, by general composition analysis (FE-TEM / EDS, etc.). Note that elements other than those specified above (e.g., impurities) may also be detected in the composition analysis, but it is sufficient that formulas (6), (7a), and (7b) are satisfied, or formulas (6), (8a), and (8b) are satisfied. Furthermore, although measurement errors may occur in the composition analysis, the c value is set taking this into consideration, and it is sufficient that 0.90≦c≦1.10.

[0053] In an embodiment of the present invention, the fourth layer can be formed by a known method. The thickness of the fourth layer is not particularly limited. In one embodiment, the thickness of the fourth layer can be, for example, 5 to 500 nm, 10 to 200 nm, or 30 to 170 nm.

[0054] In the ceramic reversible cell according to the embodiment of the present invention, the fourth layer and the third layer may be in direct contact with each other, or may not be in direct contact with each other, i.e., another layer may be present between the fourth layer and the third layer. The first layer and the fourth layer may be in direct contact with each other, or may not be in direct contact with each other, or may be in direct contact with each other, i.e., another layer may be present between the first layer and the fourth layer.

[0055] The ceramic reversible cell according to the embodiment of the present invention can be used as a steam electrolysis cell or an ammonia co-electrolysis cell. The ceramic reversible cell according to the embodiment of the present invention can also be used as a fuel cell. That is, the steam electrolysis cell (or ammonia co-electrolysis cell, or fuel cell) according to the embodiment of the present invention includes the ceramic reversible cell according to the embodiment of the present invention.

[0056] The following examples are provided to more specifically describe the embodiments of the present invention. The embodiments of the present invention are not limited to the following examples, and may be modified as appropriate within the scope of the above-described and below-described aims, and all such modifications are within the technical scope of the embodiments of the present invention.

[0057] In Example 1, a sample having a relatively thin electrolyte layer was prepared and its characteristics were evaluated.

[0058] <Preparation of Perovskite Metal Oxide Powder> Powder of the perovskite metal oxide (and / or its hydrate and / or its hydride) contained in the first layer and the second layer was prepared as follows. ３ (High Purity Chemistry), In ２ O ３ (Kanto Chemical) and ZrO ２ (High Purity Chemicals) were mixed in a ball mill in a predetermined ratio, heated at 900°C for 6 hours, then ball milled again and heated at 1300°C for 8 hours. After ball milling again, the mixture was molded using a uniaxial press and an isostatic press, and heated at 1500°C for 8 hours to obtain a dense sintered body. The powder sample was then crushed in a mortar to obtain a dense sintered body. This resulted in the formation of a perovskite-type metal oxide (hereinafter referred to as "BaZr") for the first and second layers, with A = Ba, B = Zr, M = In, and x = 0.5. ０．５ In ０．５ O ３－δ " or "BZI ５５ As a result, a powder of 1,2-dimethyl-3-pyrrolidone (sometimes referred to as "1,2-dimethyl-3-pyrrolidone") was obtained.

[0059] <Preparation of ceramic reversible cell> ５５ The powder, starch (Kanto Chemical Co., Ltd.), and NiO powder (Kojundo Chemical) were mixed in a ball mill in a weight ratio of 40:10:60, and the mixture was uniaxially molded and isostatically pressed to produce a green disk with a diameter of 15 mm and a thickness of 1.0 mm, which served as the second layer (corresponding to the fuel electrode layer).

[0060] BZI ５５ The powder was dispersed in a 1:1 mixture of binder (5 wt% ammonium stearate dissolved in α-terpineol) and polyethyleneimine (20 wt% polyethyleneimine (Mw: 28,000) dissolved in α-terpineol) solution to prepare a slurry, which was then spin-coated onto both sides of the second layer. This was sintered at 1,400°C for 8 hours, and one side was mechanically polished with a SiC abrasive. This produced the second layer (NiO-BZI ５５ ) / 1st layer (BZI ５５ ) layer structure was obtained.

[0061] The second perovskite metal oxide (Ba ０．９５ La ０．０５ FeO３－δ , hereinafter also referred to as "BLF") powder was synthesized by the citric acid precursor method. ６ H ７ O.H. ２ 0, purity 99.5%, manufactured by Kanto Chemical Co., Ltd., hereinafter referred to as "CA") as a chelating agent, so that the total molar ratio of CA to metal atoms was 2:1 and the concentration of metal atoms was 2 mol / dm ２ The precursor solution was prepared by adding and dissolving the following materials in Milli-Q (registered trademark) water to the required stoichiometric ratio (Ba:La:Fe=0.95:0.05:1). Materials: Ba(NO ３ ) ２ (purity 99%, manufactured by Kanto Chemical), La(NO ３ ) ３ ・1.5H ２ O (purity 99.99%, manufactured by Kanto Chemical), Fe(NO ３ ) ３ ・9H ２ O (purity 99.9%, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) Furthermore, a predetermined amount of CA was added to the precursor solution. This precursor solution was stirred and heated at 80°C, and H ２ The O was evaporated to promote polymerization, yielding a precursor gel. The gel was calcined at 500 °C for 1 h, and the crushed precursor powder was then fired at 1000 °C for 8 h in air to obtain BLF powder. The resulting BLF powder was molded into pellets with a diameter of 25 mm and a thickness of 5 mm, which were then sintered at 1100 °C for 6 h to obtain BLF targets for use in the pulsed laser deposition (PLD) method described below.

[0062] The BLF target obtained above was vapor-deposited on the first layer using a PLD apparatus (ULVAC UPS-10000S ultra-vacuum chamber system) to form a fourth layer.

[0063] PrBa contained in the third layer ０．５ Sr ０．５ Co １．５ Fe ０．５ O ５－δ (hereinafter also referred to as "PBSCF") powder was synthesized by the citric acid precursor method. ６ H ７ O.H. ２0, 99.5%, Kanto Chemical Co., Ltd.) as a chelating agent, so that the total mole ratio of CA to metal atom M was 2:1 and the concentration of M was 2 mol / dm ２ The precursor solution was prepared so that the required stoichiometric ratio of Sr(NO ３ ) ２ (98%, Kanto Chemical), and Co(NO ３ ) ２ ・6H ２ O (98%, Kanto Chemical), Ba(NO ３ ) ２ (99%, Kanto Chemical), Pr(NO ３ ) ３ ・3H ２ O (99.5%, FUJIFILM Wako Pure Chemical Industries, Ltd.), Fe(NO ３ ) ３ ・9H ２ 0 (99.9%, Wako Pure Chemical Industries) was dissolved in Milli-Q water, and a predetermined amount of CA was added to adjust the solution. ２ The O was evaporated to promote polymerization, yielding a precursor gel. The gel was calcined at 500 °C for 1 h, and the ground precursor powder was then calcined at 1000 °C for 8 h in air to obtain PBSCF powder.

[0064] The obtained PBSCF powder was dispersed in a 1:1 mixture of a binder (5 wt% ammonium stearate dissolved in α-terpineol) solution and a polyethyleneimine solution (20 wt% polyethyleneimine (Mw: 28,000) dissolved in α-terpineol) to prepare a slurry, which was then screen-printed onto the fourth layer to form the third layer. Finally, the layer was baked at 800°C to obtain the layer structure (second layer (NiO-BZI)) before the drying and hydrogen treatment. ５５ ) / 1st layer (BZI ５５ ) / fourth layer (BLF) / third layer (PBSCF, approximately 100 μm).

[0065] <Dry hydrogen treatment> A 3% by volume H ２ Humidified air containing O was supplied to the second layer (corresponding to the fuel electrode layer) side of the layer structure to reduce NiO in the second layer to Ni and to reduce BZI in the second layer (and the second layer side of the first layer). ５５To introduce hydride ions into the ２ / Ar gas (H ２ O concentration: 10 ppm or less by volume, H ２ Concentration: 10% by volume) was supplied, and forming was carried out at 800°C for 12 hours (hereinafter referred to as BZI with hydride ions introduced). ５５ "HBZI ５５ As a result, the ceramic reversible cell of the embodiment (second layer (Ni-HBZI ５５ ) / first layer ((H)BZI ５５ ) / fourth layer (BLF) / third layer (PBSCF). On the other hand, a 3% H ２ Humidified air containing O was supplied to the air electrode layer side, and humidified H was supplied to the second layer (corresponding to the fuel electrode layer) side of the layer structure described above so as to reduce NiO in the second layer to Ni. ２ / Ar gas (H ２ O concentration: 3% by volume, H ２ The ceramic reversible cell of the comparative example (second layer (Ni-BZI ５５ ) / 1st layer (BZI ５５ ) / fourth layer (BLF) / third layer (PBSCF).

[0066] <Neutron Diffraction> (Sample Preparation) In order to simplify the neutron diffraction measurement, the HBZI in the ceramic reversible cell of the example was ５５ and a powder sample (Sample 1) corresponding to BZI in a comparative ceramic reversible cell. ５５ A powder sample (sample 2) corresponding to the perovskite metal oxide of this example was prepared separately as follows. Furthermore, as an example in which hydride ions are introduced similarly to the perovskite metal oxide of this example, a perovskite metal oxide with A = Ba, B = Zr, M = In, and x = 0.7 (hereinafter referred to as "BaZr ０．３ In ０．７ O ３－δ " or "BZI ３７ A sample (Sample 3) was prepared by drying and hydrogen-treating powder of BaSn (hereinafter referred to as "BaSn"), and a perovskite-type metal oxide (hereinafter referred to as "BaSn") with A = Ba, B = Sn, M = In, and x = 0.7. ０．３ In ０．７ O ３－δ" or "BSI ３７ A sample (Sample 4) was prepared by drying and hydrogen-treating powder of BaCeO3 (hereinafter referred to as "BaCeO3"), and a perovskite-type metal oxide (hereinafter referred to as "BaCeO3") with A = Ba, B = Ce, M = In, and x = 0.7 (hereinafter referred to as "BaCeO3") ０．３ In ０．７ O ３－δ " or "BCI ３７ A sample (Sample 5) was prepared by dry hydrogen treatment of powder of SiO2 (sometimes referred to as "SiO2").

[0067] (Sample 1) BZI prepared according to the above-mentioned <Preparation of Perovskite Metal Oxide Powder> ５５ The powder was dried and deuterium (H ２ O concentration: 10 ppm or less by volume) at 800°C for 12 hours, and ５５ Thus, Sample 1 was obtained in which hydride ions were introduced.

[0068] (Sample 2) BZI prepared according to the above-mentioned <Preparation of Perovskite Metal Oxide Powder> ５５ The powder was dissolved in deuterium oxide (D2O) at 25°C. ２ 3% by volume D produced by bubbling in ２ The mixture was heated in an O-containing argon gas atmosphere at 300° C. for 72 hours to obtain Sample 2.

[0069] (Sample 3) In was prepared by the same method as in the above <Preparation of perovskite metal oxide powder>. ２ O ３ (Kanto Chemical) and ZrO ２ By changing the ratio of (high purity chemicals), BZI ３７ The powder obtained was BZI. ３７ The powder was dried and deuterium (H ２ The mixture was heated at 600° C. for 24 hours in a 100% O solution (O concentration: 10 ppm or less by volume) to obtain Sample 3.

[0070] (Sample 4) ZrO was prepared in the same manner as in the above <Preparation of perovskite metal oxide powder>. ２ (High Purity Chemical) SnO ２ (High Purity Chemical) and further adjusting the mixing ratio, ３７ The powder obtained was BSI. ３７ The powder was dried and deuterium (H ２The mixture was heated at 500° C. for 24 hours in a 1000 W atmosphere (O concentration: 10 ppm or less by volume) to obtain Sample 4.

[0071] (Sample 5) ZrO was prepared in the same manner as in the above <Preparation of perovskite metal oxide powder>. ２ (High Purity Chemical) CeO ２ (High Purity Chemical) and further adjusting the mixing ratio, ３７ The powder obtained was BCI. ３７ The powder was dried and deuterium (H ２ The mixture was heated at 600°C for 24 hours in a sintered body containing SrCO (O concentration: 10 ppm or less by volume) to obtain Sample 5. (Sample 6) ３ (High Purity Chemistry), In ２ O ３ (Kanto Chemical) and ZrO ２ (High Purity Chemicals) were mixed in a predetermined ratio and calcined at 800°C. After that, the mixture was crushed and mixed in a ball mill, and then molded using a uniaxial press and an isostatic press. It was then fired at 1600°C for 8 hours to obtain a dense sintered body. The powder sample was obtained by crushing the dense sintered body in a mortar. This resulted in a perovskite-type metal oxide (hereinafter referred to as "SrZr") with A = Sr, B = Zr, M = In, and x = 0.5. ０．５ In ０．５ O ３－δ " or "SZI ５５ A powder of SZI was obtained. ５５ The powder was dried and deuterium (H ２ The mixture was heated at 780° C. for 12 hours in a 1000 W atmosphere (O concentration: 10 ppm or less by volume) to obtain Sample 6.

[0072] Neutron diffraction (NRD) measurements were performed on Samples 1 to 6 using the time-of-flight method. The NRD measurements were performed using a JASRI Spica. The Rietveld analysis of the NRD patterns was performed using the Z Rietveld program. The Rietveld analysis was performed in the space group Pm-3m. Figure 4A shows the HBZI in the ceramic reversible cell of the example. ５５ The structural parameters and composition determined by NRD Rietveld analysis are shown in Table 1. In the following table, "D ｏ "teeth 、This indicates a hydrogen atom (deuterium atom) present at the oxygen site (oxygen site) of the perovskite structure. ｆｃｃ "teeth 、 This indicates a hydrogen atom (deuterium atom) present at the

[100] face center position of the perovskite structure, and is designated as "D ｏＨ "teeth 、 This shows hydrogen atoms (deuterium atoms) bonded to lattice oxygen in the perovskite structure. In Tables 1 and 3 to 6 below, it was determined that structural refinement was performed with sufficient accuracy when the S value was 3.5% or less and the Rwp value was 6% or less. Furthermore, it was determined that structural refinement was performed with even better accuracy when the Rp value was 5% or less. Table 2 also shows that, unlike the other samples, 3% by volume D ２ Sample 2 was analyzed, which was heated in O-containing argon gas. ２ Although accuracy inevitably decreases due to susceptibility to the influence of O, it was determined that structural refinement could be performed with sufficient accuracy if the S value was 9% or less and the Rwp value was 15% or less. Furthermore, it was determined that structural refinement could be performed with even better accuracy if the Rp value was 10% or less.

[0073]

[0074] The following can be seen from Table 1. The Rwp and s values ​​are sufficiently small, and the structure refinement was performed with high accuracy. From the analysis, the composition was BaZr ０．５ In ０．５ O ２．２８ D ０．４８ That is, Sample 1 (HBZI in the ceramic reversible cell of the example) ５５ (corresponding to ) satisfied the above formula (1), and when equilibrium was reached by contacting dry hydrogen having a water content of 20 ppm or less by volume at 500 to 900°C, the left side of the above formula (2) was 0.48, satisfying formula (2), and hydride ions were introduced. Furthermore, Sample 1 had a [O] / [A] ratio of 2.28 in formula (3), satisfying formula (3), which was a favorable result.

[0075] FIG. 4B shows the BZI in Sample 2 (comparative ceramic reversible cell). ５５The structural parameters and composition determined by NRD Rietveld analysis are shown in Table 2.

[0076]

[0077] From Table 2, we can see that: ２ On the assumption that the BZI in the ceramic reversible cell of the comparative example is easily affected by O, the Rwp value and s value are sufficiently small, and the structure refinement was performed with high accuracy. ５５ It was found that no hydride ions were introduced into the cathode, and that there were oxygen vacancies with a formula weight of about 0.25. This suggests that proton defects are generated in the water vapor atmosphere at the cathode according to the above formula (F4).

[0078] Figure 4C shows the NRD pattern and Rietveld calculated profile of Sample 3. The structural parameters and composition determined by NRD Rietveld analysis are shown in Table 3.

[0079]

[0080] The following can be seen from Table 3. The Rwp and s values ​​were sufficiently small, and the structure refinement was performed with high accuracy. From the analysis, the composition of Sample 3 was BaZr ０．３ In ０．７ O ２．１５ D ０．１３ It was determined that the above formula (1) was satisfied in the same manner as Sample 1, and when dry hydrogen having a water content of 20 ppm or less by volume was brought into contact with the sample at 500°C to 900°C to bring the sample into equilibrium, the left side of the above formula (2) was 0.13, which satisfied the above formula (2), and hydride ions were introduced.

[0081] Figure 4D shows the NRD pattern and Rietveld calculated profile of Sample 4. The structural parameters and composition determined by NRD Rietveld analysis are shown in Table 4.

[0082]

[0083] The following can be seen from Table 4. The Rwp value and s value were sufficiently small, and the structure refinement was performed with high accuracy. From the analysis, the composition of Sample 4 was BaSn ０．３ In ０．７ O １．８４ D ０．３６ It was determined that the above formula (1) was satisfied in the same manner as Sample 1, and when dry hydrogen having a water content of 20 ppm or less by volume was brought into contact with the sample at 500°C to 900°C to bring the sample into equilibrium, the left side of the above formula (2) was 0.36, which satisfied the above formula (2), and hydride ions were introduced.

[0084] Figure 4E shows the NRD pattern and Rietveld calculated profile of Sample 5. The structural parameters and composition determined by NRD Rietveld analysis are shown in Table 5.

[0085]

[0086] The following can be seen from Table 5. The Rwp value and s value were sufficiently small, and the structure refinement was performed with high accuracy. From the analysis, the composition of sample 5 was BaCe ０．３ In ０．７ O ２．１２ D ０．２１ It was determined that the above formula (1) was satisfied in the same manner as Sample 1, and when dry hydrogen having a water content of 20 ppm or less by volume was brought into contact with the sample at 500°C to 900°C to bring the sample into equilibrium, the left side of the above formula (2) was 0.21, which satisfied the above formula (2), and hydride ions were introduced.

[0087] Figure 4F shows the NRD pattern and Rietveld calculated profile of Sample 6. The structural parameters and composition determined by NRD Rietveld analysis are shown in Table 6.

[0088]

[0089] The following can be seen from Table 6. The Rwp and s values ​​were sufficiently small, and the structure refinement was performed with high accuracy. From the analysis, the composition of Sample 6 was SrZr ０．５ In ０．５ O ２．１５ D ０．１６It was determined that the above formula (1) was satisfied in the same manner as Sample 1, and when dry hydrogen having a water content of 20 ppm or less by volume was brought into contact with the sample at 500°C to 900°C to bring the sample into equilibrium, the left side of the above formula (2) was 0.16, which satisfied the above formula (2), and hydride ions were introduced.

[0090] <Relationship between hydrogen partial pressure and hydrogen absorption amount> HBZI in the ceramic reversible cell of the example ５５ A powder sample (Sample 1') corresponding to BZI was prepared according to the above-mentioned <Preparation of Perovskite Metal Oxide Powder>, and the relationship between the hydrogen partial pressure and the amount of hydrogen absorption was investigated. ５５ The powder was dried with hydrogen (H ２ The sample was prepared by heating at 800°C for 12 hours in a vacuum (<10 O concentration: 10 ppm or less by volume). Measurements were carried out using PCT-2DWIN (Suzuki Shokan). －４ Pa) 800°C, then cooled to the target temperature, and while maintaining that temperature, pure water gas was introduced to Ｈ２ The results are shown in FIG. 5 (horizontal axis: hydrogen partial pressure (kPa), vertical axis: hydrogen absorption amount δ Ｈ Here, at each temperature, －４ The hydrogen content of sample 1' at 100 Pa was used as the standard, and from there, each p Ｈ２ The amount of hydrogen absorbed when Ｈ The δ Ｈ is expressed as a molar ratio when the Ba content of sample 1' is set to 1. Ｈ２ With increasing δ Ｈ Increases, log δ Ｈ is logp Ｈ２ It can be seen that the gradient increases at approximately 1 / 2 with increasing hydrogen partial pressure. This result is in good agreement with the result predicted from the above formula (F1), that is, it indicates that the hydride ion defects in Sample 1' increase with increasing hydrogen partial pressure in accordance with the defect formula (F1) above. From the above, it can be seen that the HBZI in the ceramic reversible cell of the example ５５ It was confirmed that the hydride ion defects formed by defect equilibrium with gas-phase hydrogen.

[0091] <Evaluation of ceramic reversible cell characteristics (1): Steam electrolysis cell> O ２ A mixed gas of Ar / Ar=20 / 80 was passed through water at 60° C. at a total flow rate of 40 sccm to form a 3% by volume H ２ A mixed gas containing O gas was prepared and supplied to the third layer (corresponding to the air electrode layer). In the case of the cell of the example, dried H ２ / Ar mixed gas (H ２ O concentration: 10 ppm or less by volume, H ２ In the case of the comparative cell, H ２ A humidified hydrogen / Ar mixed gas (H / Ar=10 / 90) was prepared by passing a mixed gas at a total flow rate of 30 sccm through water at 25°C. ２ O concentration: 3% by volume, H ２ Concentration: 9% by volume.

[0092] Electrochemical measurements were performed using a potentio-galvanostat equipped with a frequency response analyzer (Biologic SP-300). The hydrogen evolution rate (v) of the second layer (corresponding to the anode layer) was quantified by analyzing the cathode exhaust gas using gas chromatography (490 Micro GC, Agilent Technologies). The faradaic efficiency η was calculated by multiplying the observed and theoretical hydrogen evolution rates (v), respectively. ｍｅａｓ and v ｔｈｅｏ ), and was calculated using the following equation (10): ｍｅａｓ / ν ｔｈｅｏ × 100 = ν ｍｅａｓ / (I × (z × F) －１ )×100(%) (10) Here, I is the applied current, z is the electron transport number in steam electrolysis, and F is the Faraday constant (96485 C / mol).

[0093] FIG. 6A shows a comparative example of a cell (the supply gas (H in volume ratio) on the second layer (fuel electrode layer) side). ２ O:H ２ :Ar=3:9:88) / second layer (Ni-BZI ５５ ) / 1st layer (BZI ５５ ) / 4th layer (BLF) / 3rd layer (PBSCF) / 3rd layer side supply gas (H in volume ratio)２ O:O ２ 6A shows the current-voltage (IV) curves for water electrolysis of a 1.3 V (1:19:78) ZnO / Al2O3 solution (Al2O3:Ar = 3:19:78). As shown in FIG. 6A, the open circuit voltages (OCVs) at 600°C and 500°C were 0.95 V and 0.99 V, respectively, which were only slightly lower than the ideal values ​​of 0.97 V and 1.00 V calculated using the Nernst equation. The comparative cell also had a current of 1.14 A / cm2 at 600°C and 500°C with a bias of 1.3 V, respectively. ２ and 0.56 A / cm ２ The electrolysis current density was shown.

[0094] FIG. 6B shows the cell of the example (the supply gas (H in volume ratio) on the second layer (fuel electrode layer) side). ２ O:H ２ :Ar=0.0010:10:90) / second layer (Ni-HBZI ５５ ) / first layer ((H)BZI ５５ ) / 4th layer (BLF) / 3rd layer (PBSCF) / 3rd layer side supply gas (H in volume ratio) ２ O:O ２ The current-voltage (IV) curves for the example cell (Ar = 3:19:78) are shown. The OCVs at 600°C and 500°C were 0.93 V and 0.98 V, respectively, which were almost the same as those of the comparative example cell. The electrolysis current densities of the example cell at 600°C and 500°C were 1.68 A / cm at 1.3 V, respectively. ２ and 0.84 A / cm ２ This was a higher value than the comparative cell, which was a conventional proton-conducting ceramic reversible cell.

[0095] FIG. 6C shows the AC impedance spectrum of the comparative cell measured under OCV conditions in the temperature range of 500° C. to 700° C. The x-intercept on the high frequency side is the ohmic resistance (R Ｏ ), and the semicircle that appears afterwards is mainly due to the resistance caused by the oxygen evolution reaction in the third layer (corresponding to the air cathode layer). ｐ ) is estimated from the diameter of the impedance arc. R of the comparative cell at 500 °C Ｏ and R ｐare 0.40 Ωcm ２ and 0.21 Ω cm ２ It was.

[0096] FIG. 6D shows the AC impedance spectrum of the example cell measured under OCV conditions in the temperature range of 500° C. to 700° C. The R of the example cell at 500° C. Ｏ is 0.27 Ω cm ２ , which was a lower value than the cell of the comparative example. ｐ is 0.23 Ω cm ２ and R of the comparative cell ｐ (0.21 Ω cm ２ The impedance arcs of the example cell (FIG. 6D) and the comparative example cell (FIG. 6C) matched well with each other, and the HBZI ５５ It was found that no new arcs were generated even when a layer containing

[0097] Next, at 500°C, 600 mA / cm ２ The Faraday efficiency (η) was evaluated by analyzing the exhaust gas on the second layer (corresponding to the fuel electrode layer) side by gas chromatography and quantifying the hydrogen generation rate. Figure 7A shows the cell voltage (broken line, left axis) and hydrogen generation rate (v ｍｅａｓ ) (circle plot, right side of right axis), and the transient phenomenon of the faradaic efficiency (η) (× plot, left side of right axis). As shown in FIG. 7A, the voltage (cell bias) of the comparative cell was about 1.34 V, and the overpotential, defined by the gap between the cell bias and the OCV, was calculated to be 0.35 V. In addition, the comparative cell had a voltage of about 1.4×10 －４ (mol cm －２ ・min －１ )'s v ｍｅａｓ and an η value of 73%.

[0098] FIG. 7B shows the cell voltage (broken line, left axis) and hydrogen generation rate (v ｍｅａｓ) (circle plot, right side of right axis), and the transient phenomenon of the faradaic efficiency (η) (× plot, left side of right axis). As shown in FIG. 7B, the voltage (cell bias) of the example cell was about 1.26 V, and the overpotential, defined by the gap between the cell bias and the OCV, was calculated to be 0.28 V. In addition, the example cell had a voltage of about 1.6×10 －４ (mol cm －２ ・min －１ )'s v ｍｅａｓ and an η value of about 90%, both of which were significantly higher than the results of the comparative cell.

[0099] <Evaluation of ceramic reversible cell characteristics (2): fuel cell> O ２ A mixed gas of Ar / Ar=20 / 80 was passed through water at 25° C. at a total flow rate of 80 sccm to form a 3% by volume H ２ A mixed gas containing O gas was prepared and supplied to the third layer (corresponding to the air electrode layer). In the case of the cell of the example, dried H ２ / Ar mixed gas (H ２ O concentration: 10 ppm or less by volume, H ２ In the case of the comparative cell, H ２ Humidified hydrogen / Ar mixed gas (H / Ar=10 / 90) was prepared by passing a mixed gas at a total flow rate of 80 sccm through water at 25°C. ２ O concentration: 3% by volume, H ２ Concentration: 9% by volume.

[0100] Electrochemical measurements were carried out using a potentio / galvanostat equipped with a frequency response analyzer (Biologic SP-300).

[0101] Figure 8A shows the voltage (solid line, vertical left axis) and power output curve (dashed line, vertical right axis) versus current (horizontal axis) for the comparative cell. As shown in Figure 8A, the comparative cell's power output did not increase even when the temperature was increased between 550°C (not shown) and 650°C, and its maximum power output was approximately 0.5 W / cm. ２ The output at 600 and 500°C was 0.52 W / cm ２ and 0.45 W / cm ２ It was.

[0102] Figure 8B shows the voltage (solid line, vertical left axis) and power output curve (dashed line, vertical right axis) versus current (horizontal axis) for the cell of the example. As shown in Figure 8B, the cell of the example had improved power output compared to the cell of the comparative example (Figure 8A). Furthermore, the cell of the example showed an improvement in power output with increasing temperature, with power output at 500°C, 550°C, 600°C, and 650°C being 0.58 W / cm, respectively. ２ , 0.75 W / cm ２ , 0.9 W / cm ２ and 1.08 W / cm ２ This is what happened.

[0103] 8C shows the AC impedance spectra of the comparative cell measured under OCV conditions at temperatures of 500° C. and 600° C. As shown in FIG. 8C, for example, the R Ｏ and R ｐ are 1.07 Ω cm ２ and 0.18 Ω cm ２ It was.

[0104] FIG. 8D shows AC impedance spectra of the example cells measured under OCV conditions at temperatures of 500° C. and 600° C. As shown in FIG. 8D, for example, the R Ｏ and R ｐ are 0.35 Ω cm ２ and 0.19 Ω cm ２ The cell of the example (FIG. 8D) had a lower ohmic resistance R of the first layer (corresponding to the electrolyte layer) than the cell of the comparative example (FIG. 8C). Ｏ It is believed that this resulted in an increase in output compared to the comparative example.

[0105] FIG. 9A shows a cross-sectional SEM image of the comparative cell after steam electrolysis measurement, and FIG. 9B shows a cross-sectional SEM image of the example cell after steam electrolysis measurement. In both the comparative cell and the example cell, a porous second layer 103 (or 113) was observed as the bottom layer, a dense first layer 102 (or 112) formed thereon, and a porous third layer 104 (or 114) was observed as the top layer. FIG. 9C shows an enlarged cross-sectional SEM image of the space between the first and third layers of the example cell. As shown in FIG. 9C, a fourth layer (BLF) 105 was observed between the first layer 102 and the third layer 104. Furthermore, the third layer (PBSCF) 104 was composed of particles with a diameter of approximately 100 nm. FIG. 9D shows an SEM image of the surface of the example cell after ultrasonic cleaning after removing the third layer. 9D is a low-magnification image, which clearly shows the surface morphology of the first layer 102 below the thin fourth layer 105. As can be seen from Fig. 9D, particles with a diameter of several micrometers were tightly bonded to each other on the surface of the first layer 102 of the cell of the example, and no pinholes or the like were observed.

[0106] <Evaluation of ceramic reversible cell characteristics (3): ammonia co-electrolysis cell> A 30% humidified air (H 2 in volume ratio) was placed on the third layer (corresponding to the air cathode layer) side of the ceramic reversible cell of the example. ２ O:O ２ A mixture of Ar and H2O (Ar = 30:14:56) was supplied at 130 sccm, and H2O was supplied to the second layer (corresponding to the fuel electrode layer). ２ / N ２ Mixed gas (volume ratio: H ２ :N ２ = 1:9, H ２ O concentration: 10 ppm or less by volume) was supplied at 30 sccm, and N ２ -H ２ During electrolysis, the exhaust gas from the second layer was measured with a mass spectrometer. ２ (m / z=2) and NH ３ The amount of generated m / z (m / z = 17) was quantified. －２ At a constant current density, H ２ ON ２ Co-electrolysis followed by NH ３The voltage change with time when a cycle of holding at open circuit voltage (OCV) for 5 minutes to desorb H was repeated 5 times is shown in FIG. 10B. ２ , N ２ and N.H. ３ When a constant current is applied, the signal intensity changes. ２ and N.H. ３ The signal strength of N ２ -H ２ The electrochemical synthesis of ammonia by co-electrolysis of H and O was confirmed. ２ and N.H. ３ The faradaic efficiency and production rate of were determined and are summarized in Table 7.

[0107]

[0108] As shown in Table 7, NH ３ The Faraday efficiency was about 7%, which was a relatively high value.

[0109] In Example 2, in order to clarify the characteristics of the electrolyte layer, a sample with a relatively thick electrolyte layer was prepared and its characteristics were evaluated.

[0110] As the electrolyte layer, a dense sintered body of a perovskite-type metal oxide (and / or its hydrate and / or its hydride) was prepared in the same manner as in Example 1. Specifically, BaCO ３ (High Purity Chemistry), In ２ O ３ (Kanto Chemical) and ZrO ２ (High Purity Chemicals) were mixed in a ball mill at a predetermined ratio, heated at 900°C for 6 hours, then ball milled again and heated at 1300°C for 8 hours. After ball milling again, the mixture was molded using a uniaxial press and an isostatic press, and heated at 1500°C for 8 hours to obtain an electrolyte layer (approximately 1.2 mm thick).

[0111] A Pt layer was formed as a fuel electrode layer on one surface of the electrolyte layer by applying a commercially available Pt paste (Tanaka Kikinzoku K.K.) and firing it at 900° C. for one hour.

[0112] On the other side of the electrolyte layer, a PBSCF layer was formed as an air electrode layer in the same manner as in Example 1. Finally, the layer structure before the dry hydrogen treatment (fuel electrode layer (Pt) / electrolyte layer (BZI)) was obtained by baking at 800°C. ５５ A ceramic reversible cell having a cathode layer (PBSCF, approximately 100 μm) was obtained.

[0113] The ceramic reversible cell was charged with air humidified with heavy water (volume ratio: D ２ O:O ２ :Ar=7:19:74)) was supplied to the fuel electrode layer side, and the BZI of the electrolyte layer was ５５ To introduce hydride ions into the ２ (H ２ O concentration: 10 ppm or less by volume, the remainder is H ２ The cells were heated at 800°C for 24 hours while performing steam electrolysis by applying a voltage of OCV (up to 0.9 V, sample No. 13), 1.3 V (sample No. 12), or 1.5 V (sample No. 11) between the electrodes, along with dry hydrogen treatment by supplying hydride ions. On the other hand, as a comparative example without hydride ions, heavy water-humidified air (D ２ O:O ２ :Ar=7:19:74)) was supplied to the fuel electrode layer side, and humidified H ２ (Volume ratio: H ２ O:H ２ A mixture of 100% ammonium hydroxide and 100% ammonium hydroxide (ratio: 3:97) was supplied to the furnace and heated at 800°C for 24 hours (sample No. 14).

[0114] Fig. 11A shows an optical microscope image of the side of Sample No. 14 (no dry hydrogen treatment, steam electrolysis by OCV). As shown in Fig. 11A, no hydride ions are introduced into the electrolyte layer 201 between the fuel electrode layer 202 and the air electrode layer 203, and the electrolyte layer is a homogeneous layer (i.e., proton-conducting BZI). ５５ This is because, as shown in the formula (F4) above, water vapor was supplied to both electrode sides of the cell, so the electrolyte layer was uniformly hydrated and the entire proton-conducting BZI ５５ It appears that the layer was maintained.

[0115] Fig. 11B shows an optical microscope image of the side of Sample No. 13 (dry hydrogen treatment, steam electrolysis by OCV). As shown in Fig. 11B, oxygen is lost on the fuel electrode layer 202 side of the electrolyte layer 201, and hydride ions are introduced, resulting in the formation of a proton-conducting BZI. ５５ Compared with layer 201b, the black (dark) BZI layer has hydride ions introduced therein. ５５ layer (i.e., hydride ion conducting HBZI ５５ 11B to 11D, when the applied voltage was increased, HBZI was formed in the electrolyte layer 201. ５５ The thickness of the layer 201a was increased to 0.2 mm (sample No. 13), 0.6 mm (sample No. 12), and 1 mm (sample No. 11). As shown in FIG. 11D, even though the applied voltage was high, the proton-conducting BZI was not present on the air electrode layer 203 side because heavy water-humidified air was supplied to the air electrode layer 203 side. ５５ In these cases, compared with sample No. 14, pure hydrogen was supplied to the fuel electrode layer 202 side without supplying water vapor, and therefore the hydrogenation reaction of the above formula (F2) occurred, and the BZI ５５ Layer 201b is HBZI ５５ When the applied voltage is further increased, the apparent hydrogen partial pressure p Ｈ２ As a result, in the electrolyte layer 201, the HBZI increases over a wide range from the fuel electrode layer 202 side. ５５ The high p phase is preferentially formed Ｈ２ It is believed that the partial pressure region is maintained. E = E 0 + RT / F ln(p H2 anode / p H2 cathode ) ... (F10) where R is the gas constant, T is the temperature, F is the Faraday constant, p H2 anode is the hydrogen partial pressure on the air electrode layer 203 side, p H2cathode is the hydrogen partial pressure on the fuel electrode layer 202 side.

[0116] For the cells of Samples No. 11 to 13 of the example, heavy water humidified air (D ２ O:O ２ :Ar=7:20:80) was supplied to the fuel electrode layer side, and (H ２ O concentration: 10 ppm or less by volume, the remainder is H ２ ) was supplied to the cell of Comparative Example Sample No. 14, and steam electrolysis was performed at 700° C. Heavy water-humidified air (D ２ O:O ２ :Ar=7:19:74)) was supplied to the fuel electrode layer side, and humidified H ２ (Volume ratio: H ２ O:H ２ A mixture of 1000 and 10 ... －２ A relatively small electrolysis current of 10 mA cm was observed. －２ The faradaic efficiency (shown by the triangular plot) determined by constant current electrolysis at 1.5 V was a relatively low value of about 75% (Fig. 13A). On the other hand, Samples No. 11 to 13 showed higher electrolytic performance than Sample No. 14. Sample No. 12 also showed a current of 23 mA cm at 1.5 V. －２ and 20 mA cm －２ The Faraday efficiency (shown by the triangle plot) determined by constant current electrolysis at 1000 V was 90% or more (Fig. 13B). In Fig. 13A and Fig. 13B, the solid line indicates the voltage change, and the circle plot indicates the hydrogen generation rate (V Ｈ２ ) is shown.

[0117] FIG. 14 shows the AC impedance spectra of the cells of Samples No. 11 to 14. ５５ Ohmic resistance (R Ｏ ) is shown in the graph. ５５ The layer thickness decreases (i.e., ５５ It was confirmed that the ohmic resistance decreased linearly with increasing layer thickness.５５ Layer H - Ionic conductivity is BZI ５５ Layer H ＋ This indicates that the ionic conductivity is higher than that of the ionic conductivity.

[0118] Next, the blackened layers of Samples No. 11 to 13 were treated with HBZI. ５５ To confirm that the layer is an In K-edge μXAFS measurement was carried out using a synchrotron X-ray microprobe. ５５ Layer and BZI ５５ The layer was also measured. As an example, sample No. 12 (HBZI ５５ The measurement results for a layer (thickness: about 0.6 mm) are shown in Figure 15, with an enlarged view of the vicinity of a standardized absorbance of 0.5 shown in the inset. As shown in Group A in Figure 15, when measurements were taken at positions of 0.18 mm, 0.33 mm, and 0.48 mm from the air electrode layer side toward the fuel electrode layer side (i.e., when measurements were taken on a layer that was not blackened), a standardized absorbance of 0.5 was achieved on the relatively high energy side, and this was consistent with the BZI of Example 1. ５５ On the other hand, as shown in Group B in Figure 15, when measurements were taken at positions of 0.63 mm, 0.78 mm, 0.93 mm, and 1.08 mm from the air electrode layer side toward the fuel electrode layer side (i.e., when measurements were taken at the blackened layer), the position at which the standardized absorbance = 0.5 was achieved shifted to the lower energy side, and the HBZI spectrum of Example 1 was also found to be consistent. ５５ The spectrum (dashed line) coincided with that of the BZI layer (however, when measured at a position of 0.63 mm, it was slightly higher energy). This is because the hydrogen chemical potential drops sharply at a certain point in the electrolyte layer, and the BZI ５５ Phase and HBZI ５５ This indicates a phase change.

[0119] 16 shows the results of In-K edge μXAFS measurements at positions 0.48 mm, 0.51 mm, 0.57 mm, 0.60 mm, and 0.63 mm from the air cathode layer side toward the fuel electrode layer side of Sample No. 12, with an enlarged view of the vicinity of a standardized absorbance of 0.5 being shown as an inset. As shown in the inset of FIG. 16, the spectra measured at positions 0.51 mm, 0.57 mm, 0.60 mm, and 0.63 mm from the air cathode layer side toward the fuel electrode layer side were comparable to those of the BZI of Example 1. ５５ Layer spectrum (dashed line on the high-energy side) and HBZI ５５ The BZI spectra were present in this order between the cathode and anode layers (the dashed line on the low-energy side). ５５ Phase and HBZI ５５ It is believed that a mixed phase layer is formed.

[0120] Furthermore, the blackened layers of Samples No. 11 to 13 were HBZI. ５５ As an example, the non-blackened layer (BZI) of sample No. 12 was identified as a blackened layer. ５５ The sample used had the blackened layer (layer) removed by polishing. Figure 17 shows the NRD pattern and Rietveld calculated profile of the blackened layer of Sample No. 12. The structural parameters and composition determined by NRD Rietveld analysis are shown in Table 8.

[0121]

[0122] The following can be seen from Table 8. The Rwp value and s value were sufficiently small, and the structure refinement was performed with high accuracy. From the analysis, the composition of the blackened layer of sample No. 12 was BaZr ０．５ In ０．５ O ２．２６ D ０．４５It was determined that this satisfied the above formula (1) as with Sample 1, and when dry hydrogen having a water content of 20 ppm or less by volume was brought into contact with the blackened layer at 500°C to 900°C to bring it into equilibrium, the left side of the above formula (2) was 0.45, which satisfied formula (2), and hydride ions were introduced. Furthermore, the blackened layer of Sample No. 12 had a [O] / [A] ratio of 2.26 in formula (3), which satisfied formula (3), and this was a favorable result.

[0123] This application claims priority from Japanese Patent Application No. 2023-041188, filed March 15, 2023. Japanese Patent Application No. 2023-041188 is incorporated herein by reference.

[0124] 1 Cell according to this embodiment 2 Layer containing perovskite-type metal oxide according to this embodiment or the like 3 Anode 4 Cathode 11 Conventional cell 12 Electrolyte layer 13 Anode 14 Cathode 102 First layer of example cell 103 Second layer of example cell 104 Third layer of example cell 105 Fourth layer of example cell 112 First layer of comparative example cell 113 Second layer of comparative example cell 114 Third layer of comparative example cell 201 Electrolyte layer 201a Hydride ion conducting HBZI ５５ Layer 201b Proton-conducting BZI ５５ Layer 202: Anode layer 203: Air cathode layer

Claims

1. A ceramic reversible cell comprising at least one selected from the group consisting of a perovskite metal oxide, a hydrate of the perovskite metal oxide, and a hydride of the perovskite metal oxide, The ceramic reversible cell is characterized in that the one or more selected from the group consisting of perovskite metal oxides, hydrates of perovskite metal oxides, and hydrides of perovskite metal oxides contain, as main metal atoms, A (wherein A is one or more selected from the group consisting of Ba, Sr, and Ca), B (wherein B is one or more selected from the group consisting of Zr, Sn, Ce, Ti, and Hf), and M (wherein M is one or more selected from the group consisting of In, Fe, Cr, and Mn), satisfying the following formula (1): [A]:[B]:[M]=1:a(1-x):ax...(1) In formula (1), [A], [B], and [M] represent the contents of A, B, and M, respectively, expressed in mol %, and satisfy the relationships 0.90≦a≦1.10 and 0.3≦x<1.

0.

2. 2. The ceramic reversible cell according to claim 1, wherein at least one selected from the group consisting of perovskite metal oxides, hydrates of perovskite metal oxides, and hydrides of perovskite metal oxides has a layer containing hydride ions on the fuel electrode side, and does not have a layer containing hydride ions on the air electrode side of the layer containing hydride ions.

3. 3. The ceramic reversible cell according to claim 1, wherein at least one selected from the group consisting of perovskite metal oxides, hydrates of perovskite metal oxides, and hydrides of perovskite metal oxides further satisfies the following formula (3) when brought into equilibrium at 500°C to 900°C and brought into contact with dry hydrogen having a water content of 20 ppm or less by volume: 1.5<[O] / [A]≦2.30 (3) In formula (3), [O] represents the content, in mole %, of oxygen atoms present at oxygen positions in the perovskite structure obtained from the Rietveld analysis of the neutron diffraction pattern.

4. a first layer containing at least one selected from the group consisting of the perovskite metal oxide, a hydrate of the perovskite metal oxide, and a hydride of the perovskite metal oxide; 3. The ceramic reversible cell according to claim 1, further comprising: a second layer containing at least one selected from the group consisting of the perovskite metal oxide, a hydrate of the perovskite metal oxide, and a hydride of the perovskite metal oxide; and at least one selected from the group consisting of Ni, Fe, Co, Pd, Cu, and Ru.

5. 5. The ceramic reversible cell of claim 4, comprising, in order, the second layer, the first layer, and a third layer comprising a conductive oxide.

6. A steam electrolysis cell comprising the ceramic reversible cell according to claim 1 or 2.

7. A fuel cell comprising the ceramic reversible cell according to claim 1 or 2.

8. An ammonia co-electrolysis cell comprising the ceramic reversible cell of claim 1 or 2.