Material for electrode of solid oxide electrolysis cell, member for fuel electrode, laminate, solid oxide electrolysis cell, module having solid oxide electrolysis cell, and solid oxide electrolysis cell system

Abstract

A material for an electrode of a solid oxide electrolysis cell, the material including nickel oxide and a composite oxide, wherein the composite oxide contains an alkaline earth metal element and at least one metal element that is selected from the group consisting of manganese, iron, cobalt, copper, and tin.

Description

Electrode material for solid oxide electrolysis cell, fuel electrode member, laminate, solid oxide electrolysis cell, module having solid oxide electrolysis cell, and solid oxide electrolysis cell system

[0001] The present invention relates to an electrode material for a solid oxide electrolysis cell, an anode member, a laminate, a solid oxide electrolysis cell, a module having a solid oxide electrolysis cell, and a solid oxide electrolysis cell system.

[0002] In recent years, solid oxide electrolysis cells (SOECs) have attracted attention as a highly efficient method for producing hydrogen fuel. SOECs can produce hydrogen and / or carbon monoxide by electrolyzing water vapor and / or carbon dioxide at high temperatures.

[0003] In an SOEC, the basic unit is a cell (single cell) that has two electrodes (an oxygen electrode and a fuel electrode) and a solid electrolyte layer placed between the two electrodes. An SOEC system is constructed by stacking multiple cells together and then modularizing a multi-stack that combines multiple such cell stacks.

[0004] JP 2009-263741 A

[0005] In conventional SOECs, a mixed sintered body of nickel and yttria-stabilized zirconia (YSZ) is used as the anode. Such an anode is fabricated by sintering raw material powder containing nickel oxide particles and YSZ particles in a reducing environment at high temperatures.

[0006] Since the raw material powder cannot be sintered at a low temperature, the raw material powder is usually fired at a high temperature of 1400° C. or higher.

[0007] However, such high-temperature treatment increases the manufacturing cost, and therefore there is a demand for a raw material for the anode that can be fired at a lower temperature.

[0008] Furthermore, SOECs using conventional anodes tend to experience a rise in resistance over a relatively short period of time, which can lead to a decrease in cell performance. For this reason, a more stable anode is needed.

[0009] The present invention has been made in view of the above background, and aims to provide an electrode material that can be sintered at a relatively low temperature and that can significantly suppress the deterioration of cell performance when used as a fuel electrode in an SOEC. Another aim of the present invention is to provide a solid oxide electrolysis cell that can significantly suppress the deterioration of cell performance.

[0010] The present invention provides an electrode material for a solid oxide electrolysis cell, the electrode material comprising nickel oxide and a composite oxide, wherein the composite oxide contains an alkaline earth metal element and at least one metal element selected from the group consisting of manganese, iron, cobalt, copper, and tin.

[0011] The present invention also provides a solid oxide electrolysis cell comprising an anode, an oxygen electrode, and a solid electrolyte layer between the anode and the oxygen electrode, an intermediate layer disposed between the solid electrolyte layer and the anode, the intermediate layer comprising cerium oxide, the anode comprising a nickel alloy and an oxide containing an alkaline earth metal, the nickel alloy comprising at least one metal selected from the group consisting of manganese, iron, cobalt, copper, and tin, and the ratio of the alkaline earth metal content to the nickel content in the anode is 5 mol% or more.

[0012] The present invention can provide an electrode material that can be sintered at a relatively low temperature and that can significantly suppress the deterioration of cell performance when used as a fuel electrode in an SOEC. Also, the present invention can provide a solid oxide electrolysis cell that can significantly suppress the deterioration of cell performance.

[0013] FIG. 1 is a cross-sectional view schematically showing an example of the configuration of an SOEC according to one embodiment of the present invention. FIG. 2 is a diagram schematically showing an example of the configuration of an SOEC system including an SOEC module according to one embodiment of the present invention. FIG. 3 is a flow chart schematically showing an example of a method for manufacturing an SOEC according to one embodiment of the present invention. FIG. 4 is a diagram showing an SEM-EDX elemental mapping image obtained in an anode of an SOEC according to one embodiment of the present invention. FIG. 5 is a schematic diagram of a Cole-Cole plot for explaining ohmic resistance and IR-free resistance.

[0014] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0015] One embodiment of the present invention provides an electrode material for a solid oxide electrolysis cell, the electrode material comprising nickel oxide and a composite oxide, wherein the composite oxide contains an alkaline earth metal element and at least one metal element selected from the group consisting of manganese, iron, cobalt, copper, and tin.

[0016] As mentioned above, raw material powders for conventional SOECs are typically sintered at temperatures above 1400°C. However, such high-temperature processing increases manufacturing costs. Furthermore, SOECs using conventional anodes tend to experience an increase in resistance over a relatively short operating time, resulting in a decrease in cell performance.

[0017] In contrast, an electrode material according to one embodiment of the present invention includes nickel oxide and a composite oxide, and the composite oxide includes an alkaline earth metal element and at least one metal element selected from the group consisting of manganese, iron, cobalt, copper, and tin.

[0018] Hereinafter, the at least one metal element selected from the group consisting of manganese, iron, cobalt, copper, and tin contained in the composite oxide will also be referred to as the “selected metal.” In its metallic state, the “selected metal” has the property of easily bonding with metallic nickel to form an alloy.

[0019] When such electrode materials are fired in a reducing environment, the nickel oxide is reduced to form metallic nickel. The composite oxide is decomposed to form an alkali metal oxide and a reduced "selected metal." The "selected metal" then reacts with metallic nickel to form a nickel alloy.

[0020] As a result, the product after calcination contains a nickel alloy containing the selected metal and an oxide of the alkaline earth metal. Note that the composite oxide not used in the reaction and decomposition may remain as is. Also, metallic nickel that was not alloyed may be included in the product after calcination.

[0021] Such an electrode material according to one embodiment of the present invention can be fired at a relatively low temperature because a "selected metal" that easily bonds with nickel is produced during the reductive decomposition treatment.

[0022] Furthermore, an electrode material according to one embodiment of the present invention includes an alkaline earth metal oxide that is stable in the environment in which the SOEC anode is used. Here, the electrode material does not need to have oxide ion conductivity in the environment in which it is used. If the electrode material does not have oxide ion conductivity, electrolysis proceeds at a three-phase interface formed by the gas phase, the metal contained in the electrode material in the anode, and the solid electrolyte contained in the intermediate layer or electrolyte layer adjacent to the anode. In this case, the alkaline earth metal oxide present near the three-phase interface generates CO ２ It adsorbs and activates gases such as CO ２ As a result, overvoltage is less likely to occur in electrolysis, and the resulting deterioration of the reaction field is suppressed.

[0023] Therefore, when a sintered body obtained by reducing and sintering the electrode material according to one embodiment of the present invention is used as a fuel electrode of an SOEC, the cell performance can be maintained for a relatively long period of time.

[0024] Furthermore, the electrode material according to one embodiment of the present invention uses a "selected metal" in addition to nickel as a metal component. Therefore, the electrode material according to one embodiment of the present invention can reduce the content of nickel, which is a rare metal.

[0025] Furthermore, when the electrode material according to one embodiment of the present invention is reduced at high temperatures, the composite oxide decomposes to produce the "selected metal." This significantly increases the metal content (total of metallic nickel and the "selected metal") in the anode, ensuring electrical conductivity even with a small anode mass.

[0026] Therefore, when the sintered electrode material according to one embodiment of the present invention is used for the anode of an SOEC, the anode can be made thinner, which is expected to suppress interfacial peeling and improve cell performance.

[0027] (Electrode Material According to One Embodiment of the Present Invention) Hereinafter, the characteristics of an electrode material according to one embodiment of the present invention (hereinafter referred to as "first material") will be described in more detail.

[0028] As described above, the first material contains nickel oxide and a composite oxide. Each component will be described below.

[0029] (Nickel Oxide) Nickel oxide may be present in the first material in the form of particles. The average particle size of nickel oxide is, for example, in the range of 0.1 μm to 10 μm, and preferably in the range of 0.1 μm to 5.0 μm.

[0030] (Composite Oxide) The composite oxide contains an alkaline earth metal and a "selected metal" as metal components.

[0031] The alkaline earth metal may be at least one selected from the group consisting of calcium, strontium, and barium.

[0032] The "selected metal" is selected from the group consisting of manganese, iron, cobalt, copper, and tin. As mentioned above, the "selected metal" has the property of easily alloying with metallic nickel in a high-temperature reducing environment. The composite oxide is not particularly limited as long as it satisfies the above conditions and is decomposed in a high-temperature reducing environment, and may, for example, include a composition represented by the following general formula: A ｘ M ｙ O ｚHere, x > 0, y > 0, z > 0, and 0.1≦x / y≦4, A is at least one element selected from the group consisting of calcium, strontium, and barium, and M is at least one element selected from the group consisting of manganese, iron, cobalt, copper, and tin.

[0033] Specifically, the composite oxide is, for example, CaMn ２ O ４ , CaMn ７ O １２ , CaMn ４ O ８ , Ca ２ MnO ４ , Ca ２ Mn ２ O ５ , Ca ２ Mn ３ O ８ , Ca ３ Mn ２ O ７ , CaFe ２ O ４ , CaFe ３ O ５ , CaFe ４ O ６ , CaFe ５ O ７ , CaFeO ２ , Ca ２ Fe ２ O ５ , Ca ２ Fe ４ O ７ , Ca ２ CoO ３ , Ca ２ Co ２ O ５ , Ca ３ Co ２ O ６ , CaCuO ２ , CaCu ２ O ３ , Ca ２ CuO ３ , Ca ２ SnO ４ , SrFe ２ O ４ , Sr ２ FeO ４ , Sr ２ Fe２ O ５ 、Sr ２ Fe ３ O ６ 、Sr ３ Fe ２ O ６ 、SrMn ３ O ６ 、SrMn ７ O １２ 、Sr ２ MnO ４ 、Sr ２ Mn ２ O ５ 、Sr ３ Mn ２ O ７ 、Sr ４ MnO １０ 、Sr ７ Mn ４ O １２ 、SrCo １２ O １９ 、Sr ２ Co ２ O ５ 、Sr ３ Co ２ O ６ 、Sr ５ Co ４ O １２ 、Sr ６ Co ５ O １５ 、SrCuO ２ 、SrCu ２ O ３ 、Sr ２ Cu ３ O ５ 、Sr ２ Cu ２ O ３ 、Sr ２ Cu ２ O ５ 、Sr ２ SnO ４ 、Sr ２ SnO ４ 、Sr ３ Sn ２ O ７ 、BaMnO ２ 、BaMn ２ O ３ 、BaMn ３ O ６ 、BaMn ４ O ８, BaMn ２ O ８ , Ba ４ Mn ３ O １０ , Ba ６ Mn ５ O １６ , Ba ７ Mn ４ O １５ , BaFe ４ O ７ , Ba ２ FeO ４ , Ba ２ Fe ２ O ５ , Ba ２ Fe ６ O １１ , Ba ３ FeO ５ , Ba ２ CoO ４ , Ba ２ Co ９ O １４ , Ba ３ Co １０ O １７ , BaCuO ２ , BaCu ２ O ２ , BaCu ３ O ４ , Ba ２ CuO ３ , Ba ２ Cu ３ O ６ , Ba ２ SnO ４ and solid solutions based on these and / or compounds into which oxygen vacancies have been introduced.

[0034] In the general formula, the composite oxide preferably satisfies 0.5≦x / y≦2. Furthermore, A is preferably Ca.

[0035] The composite oxide may be present in the first material in the form of particles.

[0036] The average particle size of the composite oxide is, for example, in the range of 0.1 μm to 50 μm, and preferably in the range of 0.5 μm to 20 μm.

[0037] In the first material, the molar ratio of the alkaline earth metal to nickel is 5 mol % or more, and preferably in the range of 5.0 mol % to 50 mol %, calculated as metal.

[0038] The electrode material of the present invention may contain other components as long as the effects of the invention are not impaired. The electrode material may also contain ceria. Ceria is CeO ２ , or a composition deficient in oxygen from the stoichiometric composition (e.g., CeO ２－δ In order to introduce oxygen vacancies, CeO ２ may contain another metal element.

[0039] (Form of Providing Electrode Material According to One Embodiment of the Present Invention) The form of providing the first material is not particularly limited.

[0040] The first material may be provided, for example, as a powder.

[0041] In this case, the average particle size of the nickel oxide is, for example, in the range of 0.1 μm to 10 μm, and preferably in the range of 0.1 μm to 5.0 μm.

[0042] The average particle size of the composite oxide is, for example, in the range of 0.1 μm to 50 μm, and preferably in the range of 0.5 μm to 10 μm.

[0043] Alternatively, the first material may be provided in the form of a paste.

[0044] Such a paste may be prepared by mixing a dispersion medium with a powder of the first material described above.

[0045] The dispersion medium is not particularly limited, and may be, for example, at least one of water, alcohol, ketone, ester, ether, and hydrocarbon. Among them, terpene alcohol-based solvents such as terpineol and dihydroterpineol, polyhydric alcohol-based solvents such as ethylene glycol and propylene glycol, hydrocarbon-based solvents such as decane, toluene, and xylene, and ether-based solvents such as ethyl carbitol and butyl carbitol can be used alone or in combination of two or more.

[0046] The paste may contain a binder resin to adjust viscosity and binding properties. Examples of binder resins include at least one of acrylic resin, epoxy resin, phenolic resin, alkyd resin, polyester resin, rosin resin, polycarbonate resin, and cellulose resin. Among these, it is particularly preferable to contain a cellulose-based polymer such as ethyl cellulose.

[0047] The paste may also contain additives such as a sintering aid that promotes sintering of particles in the paste formation process, or a pore former that aims to make the electrode porous.

[0048] The first material may be provided as a green sheet (unsintered compact) for an electrode (cathode) of an SOEC, composed of the first material and a binder resin. Providing the green sheet allows for efficient production of a single SOEC cell. The green sheet can be used for any of electrode-supported, solid electrolyte-supported, and metal-supported single cells. It can also be used for a monolithic sintered cell stack, which is obtained by stacking and simultaneously firing multiple green sheets corresponding to multiple single cells.

[0049] The first material may be utilized as a powder mix for the electrodes of the SOEC.

[0050] In this case, the first material may be molded in powder form and heat-treated to form an electrode, or the first paste described above may be prepared from the first mixed powder, and the electrode may be formed using this first paste.

[0051] When forming an electrode from the first paste, for example, the following steps may be performed.

[0052] First, the first paste is applied onto a support such as an electrolyte layer to form a coating film. The application method is not particularly limited, and a common method such as screen printing, doctor blade, dip coating, or spin coating may be used.

[0053] Next, the coating film may be dried and then heat-treated to form an electrode. The heat treatment temperature is preferably lower than 1450°C, for example, in the range of 900°C to 1200°C.

[0054] (SOEC According to an Embodiment of the Present Invention) Next, an SOEC according to an embodiment of the present invention will be described.

[0055] One embodiment of the present invention provides a solid oxide electrolysis cell comprising an anode, an oxygen electrode, and a solid electrolyte layer between the anode and the oxygen electrode; an intermediate layer is disposed between the solid electrolyte layer and the anode, the intermediate layer comprising cerium oxide; the anode comprises a nickel alloy and an oxide containing an alkaline earth metal; the nickel alloy comprises at least one metal selected from the group consisting of manganese, iron, cobalt, copper, and tin; and the ratio of the alkaline earth metal content to the nickel content in the anode is 5 mol% or more.

[0056] FIG. 1 shows a schematic diagram of the structure of an SOEC (hereinafter referred to as a "first cell") according to one embodiment of the present invention.

[0057] In FIG. 1, the first cell has an electrolyte layer-supported structure.

[0058] As shown in FIG. 1, the first cell 100 has an anode 110 , an cathode 120 , and a solid electrolyte layer 130 disposed between the anode 110 and the cathode 120 .

[0059] The first cell 100 also has a first intermediate layer 150 between the fuel electrode 110 and the solid electrolyte layer 130 , and a second intermediate layer 160 between the oxygen electrode 120 and the solid electrolyte layer 130 .

[0060] The first intermediate layer 150 and the second intermediate layer 160 are provided to suppress solid-state reactions between the respective electrodes 110 , 120 and the solid electrolyte layer 130 .

[0061] However, the second intermediate layer 160 may be omitted.

[0062] When the first cell 100 is connected to an external power source 170, the following reaction occurs at the anode 110: ２ O+4e － →2H ２ +20 ２－ (1) Formula 2CO ２ +4e － → 2CO + 2O ２－ (2) Oxide ions generated at the fuel electrode 110 pass through the solid electrolyte layer 130 and reach the oxygen electrode 120 on the opposite side.

[0063] At the oxygen electrode 120, for example, the following reaction occurs: ２－ →O ２ +4e － Formula (3) Therefore, by continuing the reactions of formulas (1) to (3), fuel such as hydrogen and / or carbon monoxide can be obtained from the fuel electrode 110.

[0064] Here, in the first cell 100, the anode 110 is formed by reducing and firing the first material having the above-mentioned characteristics.

[0065] Therefore, in the first cell 100, it is possible to significantly suppress an increase in the resistance of the anode 110. Furthermore, this makes it possible to significantly suppress a decrease in the cell performance during operation in the first cell 100.

[0066] (Regarding Each Component) Next, each component constituting the first cell 100 will be described in more detail.

[0067] (Anode 110) The anode 110 has the role of electrolyzing water vapor and / or carbon dioxide at the operating temperature.

[0068] The anode 110 is formed by firing the first material in a reducing environment at high temperature.

[0069] Alternatively, the anode 110 may be formed during the initial electrolysis stage of the first cell 100. In this case, an "anode member" is first formed by pre-sintering a first material. Next, after constructing the first cell 100 including the "anode member," the anode 110 is formed by reducing the "anode member" when the initial electrolysis by the first cell 100 begins.

[0070] The term "fuel electrode member" refers to a member that is converted into a fuel electrode by being exposed to a high-temperature reducing environment.

[0071] The anode 110 includes a nickel alloy and an oxide containing an alkaline earth metal.

[0072] The nickel alloy includes at least one metal selected from the group consisting of manganese, iron, cobalt, copper and tin.

[0073] The oxide containing an alkaline earth metal may include an oxide of at least one metal selected from calcium, strontium, and barium, and may be, for example, CaO, SrO, or BaO.

[0074] The anode 110 may further include a composite oxide containing an oxide of the aforementioned "selected metal." Such a composite oxide exists as an unreacted residue when the first material is calcined in a reducing environment at high temperature.

[0075] The composite oxide is, for example, CaMn ２ O ４ , CaMn ７ O １２ , CaMn ４ O ８ , Ca ２ MnO ４ , Ca ２ Mn ２ O ５、 ２ Mn ３ O ８ 、 ３ Mn ２ O ７ 、Cqｦe ２ O ４ 、Cqｦe ３ O ５ 、Cqｦe ４ O ６ 、Cqｦe ５ O ７ 、CqｦeO ２ 、 ２ Fe ２ O ５ 、 ２ Fe ４ O ７ 、 ２ CoO ３ 、 ２ Co ２ O ５ 、 ３ Co ２ O ６ 、CCCO ２ 、111 ２ O ３ 、 ２ COO ３ 、 ２ SnO ４ 、Srｦe ２ O ４ 、Sr ２ FeO ４ 、Sr ２ Fe ２ O ５ 、Sr ２ Fe ３ O ６ 、Sr ３ Fe ２ O ６ 、SrMn ３ O ６ 、SrMn ７ O １２ 、Sr ２ MnO ４ 、Sr ２ Mn ２ O ５ 、Sr ３ Mn ２ O ７ 、Sr ４ MnO １０ 、Sr ７ Mn４ O １２ 、Sr"o １２ O １９ 、Sr ２ Co ２ O ５ 、Sr ３ Co ２ O ６ 、Sr ５ Co ４ O １２ 、Sr ６ Co ５ O １５ 、SrCuO ２ 、SrCu ２ O ３ 、Sr ２ Cu ３ O ５ 、Sr ２ Cu ２ O ３ 、Sr ２ Cu ２ O ５ 、Sr ２ SnO ４ 、Sr ２ SnO ４ 、Sr ３ Se ２ O ７ 、BMMO ２ 、 ２ O ３ 、 ３ O ６ 、 ４ O ８ 、 ２ O ８ 、 ４ Mn ３ O １０ 、 ６ Mn ５ O １６ 、 ７ Mn ４ O １５ 、Baｦe ４ O ７ 、 ２ FeO ４ 、 ２ Fe ２ O ５ 、 ２ Fe ６ O １１ 、 ３ FeO ５, Ba ２ CoO ４ , Ba ２ Co ９ O １４ , Ba ３ Co １０ O １７ , BaCuO ２ , BaCu ２ O ２ , BaCu ３ O ４ , Ba ２ CuO ３ , Ba ２ Cu ３ O ６ , Ba ２ SnO ４ and solid solutions based on these and / or compounds into which oxygen vacancies have been introduced.

[0076] The ratio of the alkaline earth metal content to the nickel content is 5 mol % or more, and preferably in the range of 5.0 mol % to 50 mol %.

[0077] By setting the ratio of the alkaline earth metal content to the nickel content to 5 mol % or more, it becomes possible to significantly suppress the deterioration of cell performance.

[0078] (Oxygen Electrode 120) The oxygen electrode 120 is made of a material that can remove electrons from oxide ions and generate gaseous oxygen molecules.

[0079] A conventionally known material may be used for the oxygen electrode 120. For example, the oxygen electrode 120 may be made of lanthanum strontium cobalt oxide (La １－ｘ Sr ｘ CoO ３ ) (where 0≦x≦1), lanthanum-strontium-cobalt-iron oxide (La １－ｘ Sr ｘ Co １－ｙ Fe ｙ O ３ ) (where 0≦x≦1, 0≦y≦1), lanthanum strontium manganese oxide (La １－ｘ Sr ｘ MnO ３) (where 0≦x≦1), ceria-based oxides, and mixtures thereof can be used. In particular, it is preferable to use a perovskite-type oxide containing two or more elements selected from the group consisting of La, Sr, Co, Fe, and Mn.

[0080] In the case of a fuel electrode-supported structure, after forming the solid electrolyte layer, a paste containing powder for the oxygen electrode may be applied and fired to form the oxygen electrode.

[0081] In the case of a solid electrolyte layer-supported structure, the oxygen electrode may be formed by applying a paste containing powder for the oxygen electrode onto a solid electrolyte substrate and firing the applied paste. A ceria-based electrolyte may be formed between the solid electrolyte layer and the oxygen electrode as a reaction prevention layer.

[0082] (Solid Electrolyte Layer 130) The solid electrolyte layer 130 is made of a material that has oxide ion conductivity at the operating temperature.

[0083] The solid electrolyte layer 130 may be made of a conventionally known material, such as yttria-stabilized zirconia (YSZ), scandia-stabilized zirconia (ScSZ), lanthanum strontium gallium magnesium oxide (LaSZ), or the like. １－ｘ Sr ｘ Ga １－ｙ Fe ｙ O ３ ) (where 0≦x≦1, 0≦y≦1) is used. In addition, any material having oxide ion conductivity can be used other than the above compounds.

[0084] (First Intermediate Layer 150 and Second Intermediate Layer 160) The first intermediate layer 150 is disposed between the anode 110 and the solid electrolyte layer 130. The second intermediate layer 160 is disposed between the cathode 120 and the solid electrolyte layer 130.

[0085] By providing the first intermediate layer 150, it is possible to suppress a solid-phase reaction between the anode 110 and the solid electrolyte layer 130, and to prevent deterioration of the solid electrolyte layer 130 and the anode 110.

[0086] The same applies to the second intermediate layer 160 .

[0087] The first and second intermediate layers 150, 160 are made of, for example, an oxide containing cerium, which is preferable because of its excellent ion conductivity.

[0088] The cerium-containing oxide may be cerium oxide doped with a rare earth element such as gadolinium (Gd) or samarium (Sm), or an alkaline earth metal element, for example. The doping amount of the rare earth element such as Gd or samarium, or the alkaline earth metal element, is, for example, in the range of 0 to 20 mol %.

[0089] Although the configuration of an SOEC according to one embodiment of the present invention has been described above using an electrolyte layer-supported structure as an example, it should be noted that the SOEC according to one embodiment of the present invention can also be applied to an anode-supported structure or a porous substrate-supported structure in addition to the electrolyte layer-supported type.

[0090] (SOEC System) The SOEC according to one embodiment of the present invention is used as an SOEC system including a stack formed by laminating a plurality of the SOECs, and a module formed by combining a plurality of these stacks.

[0091] FIG. 2 shows a schematic diagram of an example of the configuration of such an SOEC system.

[0092] As shown in FIG. 2, the SOEC system 201 includes an SOEC module 210 , a power supply 220 , a gas supply 230 , a gas separation device 240 , and a storage device 250 .

[0093] The SOEC module 210 is constructed by stacking multiple SOECs in series. The power supply device 220 serves to supply necessary power to the SOEC module 210. The gas supply device 230 serves to supply reactant gases such as water vapor and / or carbon dioxide to the SOEC module 210. The gas separation device 240 serves to separate the product gases generated in the SOEC module 210. The storage device 250 serves to store the hydrogen and / or carbon monoxide separated in the gas separation device 240.

[0094] During operation of the SOEC system 201, power from the power supply 220 heats the SOEC module 210 to an operating temperature, which is 700°C or higher, for example, in the range of 700°C to 900°C.

[0095] Next, a reaction gas containing water vapor and / or carbon dioxide is supplied from the gas supply device 230 to the high-temperature SOEC module 210. The reaction gas is supplied to the fuel electrode side of each SOEC constituting the SOEC module 210.

[0096] Next, an electrolysis voltage is applied from the power supply device 220 to the SOEC module 210, and electrolysis begins in the SOEC module 210.

[0097] Electrolysis generates electrolytic gases in each SOEC included in the SOEC module 210. That is, hydrogen and / or carbon monoxide are generated from the fuel electrode, and oxygen is generated from the oxygen electrode.

[0098] The hydrogen and / or carbon monoxide produced at the anode is separated by the gas separation device 240. The hydrogen and / or carbon monoxide separated by the gas separation device 240 is stored in the storage device 250.

[0099] The oxygen produced at the oxygen electrode may be collected and stored by a separate device.

[0100] In the SOEC system 201, each SOEC constituting the SOEC module 210 is an SOEC according to one embodiment of the present invention (for example, the first cell described above).

[0101] Therefore, in the SOEC system 201, the degradation of cell performance can be significantly suppressed.

[0102] (Method of Manufacturing an SOEC According to an Embodiment of the Present Invention) Next, an example of a method of manufacturing an SOEC according to an embodiment of the present invention will be described with reference to FIG.

[0103] FIG. 3 is a schematic diagram showing a flow of a method for manufacturing an SOEC according to one embodiment of the present invention.

[0104] As shown in FIG. 3 , a method for manufacturing an SOEC according to one embodiment of the present invention (hereinafter referred to as the “first method”) includes the steps of: (1) providing a first intermediate layer on a first surface of an electrolyte layer (step S110); (2) providing an anode member on the first intermediate layer (step S120); and (3) providing an oxygen electrode on the side of the electrolyte layer opposite the first intermediate layer (step S130).

[0105] Each step will be described below using the electrolyte layer-supported type as an example. For clarity, the following description will use the first cell 100 as an example to describe the manufacturing method. Therefore, the reference symbols shown in FIG. 1 will be used to represent each component.

[0106] (Step S110) First, a solid electrolyte layer 130 having a first surface and a second surface facing each other is prepared.

[0107] The shape of the solid electrolyte layer 130 is not particularly limited, and the solid electrolyte layer 130 may be plate-shaped or disk-shaped.

[0108] The solid electrolyte layer 130 may be composed of YSZ or ScSZ, as previously described.

[0109] Next, a first intermediate layer 150 is formed on a first surface of the solid electrolyte layer 130. If necessary, a second intermediate layer 160 may be formed on a second surface of the solid electrolyte layer 130.

[0110] The first intermediate layer 150 is formed as follows.

[0111] A first intermediate layer paste is applied to the first surface of the solid electrolyte layer 130. The first intermediate layer paste includes, for example, a solvent, cerium-based oxide particles, and a binder. The cerium-based oxide may be Gd-doped cerium oxide.

[0112] The method for applying the first intermediate layer paste is not particularly limited. The first intermediate layer paste may be applied to the first surface of the solid electrolyte layer 130 by, for example, brush coating or screen printing.

[0113] The first intermediate layer paste is then dried and then fired at a firing temperature in the range of, for example, 1200° C. to 1400° C. Thus, the first intermediate layer 150 is formed.

[0114] If desired, the second intermediate layer 160 is formed in a similar manner.

[0115] (Step S120) Next, an anode member, which will be converted into the anode 110 later, is formed on the first intermediate layer 150.

[0116] The fuel electrode member is formed as follows.

[0117] First, an anode paste is applied to the surface of the first intermediate layer 150. The anode paste includes, for example, a solvent, mixed particles, and a binder.

[0118] As the solvent, for example, α-terpineol and polyethylene glycol (PEG) can be used.

[0119] The binder may be polyvinyl butyral (PVB), ethyl cellulose (EC), or the like.

[0120] The mixed particles are composed of the first material described above.

[0121] The method for applying the anode paste is not particularly limited. The anode paste may be applied onto the first intermediate layer 150 by, for example, brush coating or screen printing.

[0122] Thereafter, the anode paste is dried and then fired.

[0123] The firing temperature may be, for example, in the range of 1100°C to 1300°C. As described above, conventional material systems containing YSZ require high-temperature firing (e.g., 1400°C), and it is difficult to reduce the firing temperature. However, in the first method, the anode paste contains mixed particles composed of the first material described above, and therefore can be fired at a relatively low temperature.

[0124] In this way, the fuel electrode member is formed.

[0125] (Step S130) Next, the oxygen electrode 120 is formed on the second surface of the solid electrolyte layer 130 (or the second intermediate layer 160, if present; the same applies below).

[0126] The oxygen electrode 120 is formed as follows.

[0127] First, an oxygen electrode paste is applied to the second surface of the solid electrolyte layer 130. The oxygen electrode paste includes, for example, a solvent, mixed particles, and a binder.

[0128] As the solvent and binder, for example, the solvent and binder used in the above-mentioned paste for the fuel electrode can be used.

[0129] The mixed particles may be made of a material that constitutes a conventional oxygen electrode. For example, the mixed particles may be made of lanthanum strontium cobalt oxide (La １－ｚ Sr ｚ CoO ３ ) where 0≦z≦1.

[0130] The method for applying the paste for the oxygen electrode is not particularly limited. The paste for the oxygen electrode may be applied to the second surface of the solid electrolyte layer 130 by, for example, brushing or screen printing.

[0131] The cathode paste is then dried and then fired at a firing temperature ranging from 900°C to 1100°C, for example, although this temperature varies depending on the type of mixed particles contained in the cathode paste.

[0132] As a result, the oxygen electrode 120 is formed.

[0133] Thereafter, the fuel electrode member is reduced in a high-temperature environment to form the fuel electrode 110 .

[0134] Through the above steps, the SOEC according to one embodiment of the present invention can be manufactured.

[0135] However, it will be apparent to those skilled in the art that the above method is merely an example and that the SOEC according to an embodiment of the present invention may be manufactured by other methods. That is, the SOEC according to an embodiment of the present invention may be manufactured by any method as long as an anode having the above-described characteristics is obtained.

[0136] For example, in the first method, an anode member is formed in step S120. The anode member is converted into an anode, for example, after the SOEC has started to be used. However, alternatively, in step S120, the anode may be formed on first intermediate layer 150 by firing the dried anode paste in a high-temperature reducing environment.

[0137] Various other modifications are possible.

[0138] Examples of the present invention will be described below. In the following description, Examples 1 to 7 are examples, and Examples 11 to 16 are comparative examples.

[0139] Example 1 An SOEC was fabricated by the following method.

[0140] (Formation of First and Second Intermediate Layers) First, an intermediate layer was formed on each surface of the solid electrolyte layer by the following procedure: For the solid electrolyte layer, a YSZ substrate (manufactured by Tosoh Corporation, diameter 20 mm, thickness 500 μm) was used.

[0141] 10 mol% gadolinium-doped ceria (Ce ０．９ Gd ０．１ O ２ A paste-like composition (referred to as "first paste") was prepared by kneading α-terpineol solvent (Fujifilm Wako Pure Chemical Industries, Ltd.) with α-terpineol powder (GDC standard for testing and research, manufactured by AGC Seimi Chemical Co., Ltd.) in a mass ratio of 50:50.

[0142] Masking tape was applied to the first surface of the YSZ substrate except for a region with a diameter of 12 mm at the approximate center, and then the first paste was applied to the first surface of the YSZ substrate.

[0143] Next, the YSZ substrate was turned over, and the first paste was applied to the second surface in the same manner.

[0144] Next, the YSZ substrate was dried at 140° C. and then heated to 1400° C. As a result, a first intermediate layer having a diameter of 12 mm was formed on the first surface of the YSZ substrate, and a second intermediate layer having a diameter of 12 mm was formed on the second surface.

[0145] (Fabrication of Anode Member) Next, an anode member was fabricated in the following manner.

[0146] (Ca ２ Fe ２ O ５ Preparation of calcium carbonate (3.682 g, manufactured by Kojundo Chemical Laboratory) and Fe ２ O ３ (2.937 g, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were weighed out. These were placed in a pot containing zirconia balls with a diameter of 5 mm and 10 cc of isopropanol (manufactured by Sankyo Chemical Industry Co., Ltd.), and were ground and mixed for 3 hours using a planetary ball mill.

[0147] Next, the mixed powder was dried at 100°C to remove isopropanol. Furthermore, the mixed powder was separated from the zirconia balls using a sieve. The obtained mixed powder was placed in an alumina crucible and calcined in air at 1100°C for 10 hours. The obtained sample was crushed in an agate mortar and mortar to remove Ca. ２ Fe ２ O ５ A powder was produced.

[0148] Ca ２ Fe ２ O ５ The powder had an average particle size of 5.9 μm, which means the 50% volume average particle size in the particle size distribution measured by a particle size distribution measuring device based on a laser scattering / diffraction method.

[0149] (Preparation of Paste) Next, nickel oxide (NiO, manufactured by Kojundo Chemical Laboratory) was crushed in an agate mortar to obtain powder (average particle size 1.0 μm) and the above-mentioned Ca ２ Fe ２ O ５ The alkali metal and nickel powders were mixed in a weight ratio of 89:11 to prepare a mixed powder. In the mixed powder, the content of the alkali metal relative to nickel was 6.9% in terms of molar ratio.

[0150] A solvent (polyethylene glycol PEG400, manufactured by Kokusan Chemical Co., Ltd.) was added to this mixed powder and kneaded to prepare a paste-like composition (hereinafter referred to as "second paste").

[0151] (Paste application and firing of coating film) Next, two masking tapes were attached to the first intermediate layer except for a 10 mm diameter region at approximately the center, and then the second paste was applied to the first intermediate layer to form a second coating film. The second coating film was then dried at 230°C, and the assembly was fired at 1100°C to form an anode member.

[0152] (Formation of Oxygen Electrode) A paste-like composition (hereinafter referred to as "third paste") was prepared.

[0153] The third paste has the composition (La ０．６０ Sr ０．４０ ) ０．９５ (Co ０．２０ Fe ０．８０ ) O ３ It is a paste containing powder of (LSCF-1; manufactured by Fuel Cell Materials).

[0154] Masking tape was applied to the second intermediate layer except for a region of 6 mm diameter at the approximate center, and then the third paste was applied onto the second intermediate layer.

[0155] Next, the third coating film was dried at 140° C. and then further baked at 1060° C. This formed an oxygen electrode.

[0156] Through the above steps, an SOEC was fabricated.

[0157] The resulting SOEC is referred to as "Cell 1."

[0158] (Examples 2 to 3) SOECs were fabricated in the same manner as in Example 1. However, in Examples 2 and 3, the third paste was first applied to the second intermediate layer and fired at 1,060°C to form an anode. Thereafter, the second paste was applied to the first intermediate layer and fired at 1,000°C (Example 2) and 900°C (Example 3) to form anode members.

[0159] The resulting SOECs are referred to as "Cell 2" and "Cell 3," respectively.

[0160] (Examples 4 to 6) SOECs were fabricated in the same manner as in Example 1. However, in Examples 4 to 6, the nickel oxide powder and Ca contained in the second paste were ２ Fe ２ O ５ The mixing ratio of nickel oxide powder and Ca powder was changed from that in Example 1. ２ Fe ２ O ５ The weight ratio of the powders was 47:53 in Example 4, and 73:27 in Examples 5 and 6. In Examples 4 to 6, similarly to Examples 2 and 3, the third paste was first applied to the second intermediate layer and fired at 1060°C to form an anode. Thereafter, the second paste was applied to the first intermediate layer and fired at 1000°C to form an anode member.

[0161] In Example 6, the amount of polyethylene glycol used in preparing the second paste was half that of Example 1. Furthermore, the number of masking tapes attached to the top of the first intermediate layer was changed from two to one.

[0162] The obtained SOECs are referred to as "Cell 4" to "Cell 6", respectively.

[0163] Example 7 An SOEC was fabricated in the same manner as in Example 1. However, in Example 7, the composite oxide contained in the second paste for the anode was Ca. ２ Fe ２ O ５ Instead of powder, CaFe ２ O ４ Powder was used. ２ O ４ The powder was prepared as follows.

[0164] (CaFe ２ O ４ Preparation of calcium carbonate (2.319 g, manufactured by Kojundo Chemical Laboratory) and Fe ２ O ３(3.701 g, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were weighed out. These were placed in a pot containing zirconia balls with a diameter of 5 mm and 10 cc of isopropanol (manufactured by Sankyo Chemical Industry Co., Ltd.), and were ground and mixed for 3 hours using a planetary ball mill.

[0165] Next, the mixed powder was dried at 100°C to remove the isopropanol. Furthermore, the mixed powder was separated from the zirconia balls using a sieve. The obtained mixed powder was placed in an alumina crucible and calcined in air at 1000°C for 10 hours. The obtained sample was crushed in an agate mortar to obtain CaFe ２ O ４ A powder was produced.

[0166] CaFe ２ O ４ The average particle size of the powder was 6.5 μm.

[0167] In the mixed powder, nickel oxide powder and CaFe ２ O ４ The weight ratio of the powders was 87:13, and the content of alkali metal relative to nickel was 5.3% in molar ratio.

[0168] The resulting SOEC is referred to as "Cell 7."

[0169] (Example 11) An SOEC was fabricated in the same manner as in Example 1. However, in this Example 11, the powder contained in the second paste for the anode was nickel oxide powder and iron oxide (Fe ２ O ３ The nickel oxide powder and the iron oxide powder were mixed to prepare a powder (average particle size: 0.61 μm) of nickel oxide powder (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) in an agate mortar. The weight ratio of the nickel oxide powder to the iron oxide powder was 87:13.

[0170] The resulting SOEC is referred to as "Cell 11."

[0171] (Example 12) An SOEC was fabricated in the same manner as in Example 1. However, in this Example 12, the powder contained in the second paste for the anode was Ca. ２ Fe ２ O ５ Only powder (average particle size 5.9 μm) was used.

[0172] The resulting SOEC is referred to as "Cell 12."

[0173] In Example 12, after the anode coating film was baked, the anode member peeled off from the solid electrolyte layer, and subsequent evaluations could not be carried out.

[0174] (Examples 13 to 16) SOECs were fabricated in the same manner as in Example 1. However, in these examples, the anode member was composed of a mixture of nickel oxide powder and YSZ powder. The weight ratio of nickel oxide powder to YSZ powder was 66:34 in Examples 13, 15, and 16, and 39:61 in Example 14. In addition, a first intermediate layer was not formed.

[0175] In Example 13, the coating film for the anode was fired at 1100° C. However, in Example 13, the resistance of the obtained SOEC was too high and it could not be used as a cell, so the subsequent evaluations were not carried out.

[0176] In Examples 14 to 16, the coating film for the anode was fired at 1400° C. to produce the cells.

[0177] The SOECs obtained in Examples 14 to 16 are referred to as "Cell 14" to "Cell 16," respectively.

[0178] Table 1 below shows a comparison of some of the manufacturing conditions for each cell.

[0179] Here, in the column "Electrode thickness after fuel electrode formation" in Table 1, the thickness of the fuel electrode obtained in each cell after the pretreatment described below was recorded.

[0180] (Pretreatment) The following pretreatment was carried out on each cell in order to convert the fuel electrode member into a fuel electrode.

[0181] First, a mixed gas of hydrogen and argon (hydrogen:argon=20:80 (volume ratio)) was supplied to the fuel electrode side. The hydrogen supply rate was 20 ml / min and the argon supply rate was 80 ml / min, and this was maintained for 20 minutes.

[0182] Next, a mixed gas of a different composition (hydrogen:argon = 50:50 (volume ratio)) was supplied. The hydrogen supply rate was 50 ml / min, and the argon supply rate was 50 ml / min, and these were maintained for 20 minutes. Thereafter, only hydrogen gas was supplied. The hydrogen supply rate was 100 ml / min, and these were maintained for 20 minutes.

[0183] Next, a mixed gas of hydrogen and water vapor (hydrogen:water vapor=97:3 (volume ratio)) was supplied to the fuel electrode side. The hydrogen supply rate was 97 ml / min, and the water vapor supply rate was 3 ml / min.

[0184] Thereafter, the current value was adjusted so that the operating voltage of the cell was between 0.55 V and 0.65 V, and the cell was operated in a power generation mode for 5 hours to complete the pretreatment.

[0185] During the pretreatment, pure oxygen was supplied to the oxygen electrode side at a supply rate of 100 ml / min.

[0186] (Evaluation) The following evaluations were carried out using each cell.

[0187] (Confirmation of the Presence or Absence of Nickel Alloy Formation) Each cell was evaluated for the presence or absence of nickel alloy in the fuel electrode.

[0188] Specifically, when SEM-EDX elemental mapping of the fuel electrode shows a region where the location of nickel and the location of iron coincide, it is determined that a nickel-iron alloy is formed in the fuel electrode.

[0189] FIG. 4 shows an SEM-EDX elemental mapping image obtained for the fuel electrode of cell 1.

[0190] This figure shows that Ni and Fe were detected in the same particle. It was also confirmed that the particle did not contain O. This indicates that in the case of cell 1, at least a portion of the nickel in the anode was alloyed with iron.

[0191] Similar results were obtained in cells 2 to 7.

[0192] (Resistance Measurement) AC impedance measurement was carried out on each cell to evaluate the area specific resistance.

[0193] In the AC impedance measurement, the frequency range was 100 kHz to 100 mHz, and the current density was 0.2 A / cm ２ and the amplitude is 0.04 A / cm ２ It was decided.

[0194] From the obtained Cole-Cole plot, the intersection A with the horizontal axis on the high frequency side (real axis Z') and the intersection B with the horizontal axis on the low frequency side (real axis Z') were determined. The value at intersection A was taken as the ohmic resistance, and the value between intersection A and intersection B was taken as the IR-free resistance.

[0195] FIG. 5 is a diagram schematically showing a Cole-Cole plot obtained by AC impedance measurement.

[0196] In FIG. 5, the horizontal axis is the real axis Z' and the vertical axis is the imaginary axis Z''.

[0197] In such a Cole-Cole plot, the length R １ corresponds to the value of the ohmic resistance, and the length R ２ corresponds to the value of the IR-free resistor.

[0198] (Measurement of Cell Aging Changes) Each cell was operated at 800° C., and the change in operating voltage during electrolysis was measured.

[0199] The measurement device used was a single cell evaluation device for solid oxide fuel cells, BEL-SOFC (manufactured by MicrotrackBell).

[0200] A mixed gas of hydrogen, argon, water vapor, and carbon dioxide (hydrogen:argon:water vapor:carbon dioxide = 10:70:10:10 (volume ratio)) was supplied to the fuel electrode side. The hydrogen supply rate was 10 ml / min, the argon supply rate was 70 ml / min, the water vapor supply rate was 10 ml / min, and the carbon dioxide supply rate was 10 ml / min. On the other hand, pure oxygen was supplied to the oxygen electrode side at a supply rate of 100 ml / min.

[0201] The electrolysis current density was 0.2 A / cm ２ The electrolysis time was 25 hours. However, for cells 14 and 16, the electrolysis current density was set to 0.05 A / cm because of high resistance. ２ It was decided.

[0202] Electrolysis voltage (V ２５ ) was measured. Also, for each cell, the voltage change rate V ２５ / V ０ The ratio of V ０ is the initial electrolysis voltage.

[0203] Table 2 below shows the evaluation results obtained for each cell.

[0204] As shown in Table 2, it was found that in cells 1 to 7, nickel was alloyed with iron.

[0205] It was also found that the total resistance of the cells was reduced in cells 1 to 7 compared to cells 11 to 16. Furthermore, it was found that the increase in electrolysis voltage after 25 hours was significantly suppressed in cells 1 to 7 compared to cells 11 to 16.

[0206] (Aspects of the Invention) The present invention may have the following aspects.

[0207] (Aspect 1) An electrode material for a solid oxide electrolysis cell, comprising nickel oxide and a composite oxide, wherein the composite oxide contains an alkaline earth metal element and at least one metal element selected from the group consisting of manganese, iron, cobalt, copper, and tin.

[0208] (Aspect 2) The composite oxide has the general formula: ｘ M ｙ O ｚ wherein x>0, y>0, z>0, A is at least one element selected from the group consisting of calcium, strontium, and barium, M is at least one element selected from the group consisting of manganese, iron, cobalt, copper, and tin, and 0.1≦x / y≦4.

[0209] (Embodiment 3) The electrode material according to embodiment 1 or 2, wherein the composite oxide satisfies 0.5≦x / y≦2.

[0210] (Aspect 4) A powder containing the electrode material according to any one of Aspects 1 to 3.

[0211] (Aspect 5) The powder according to aspect 4, wherein the nickel oxide has an average particle size of 0.1 μm or more and 10 μm or less.

[0212] (Aspect 6) The powder according to aspect 4 or 5, wherein the composite oxide has an average particle size of 0.1 μm or more and 50 μm or less.

[0213] (Aspect 7) A paste containing the powder according to any one of aspects 4 to 6.

[0214] (Embodiment 8) A fuel electrode member for a solid oxide electrolysis cell, comprising the electrode material according to any one of embodiments 1 to 3.

[0215] (Aspect 9) A laminate for a solid oxide electrolysis cell, comprising: an anode member, an oxygen electrode, and a solid electrolyte layer between the anode member and the oxygen electrode; an intermediate layer is disposed between the solid electrolyte layer and the anode member, the intermediate layer comprising cerium oxide; and the anode member includes the electrode material according to any one of Aspects 1 to 3.

[0216] (Aspect 10) A solid oxide electrolysis cell comprising: an anode, an oxygen electrode, and a solid electrolyte layer between the anode and the oxygen electrode; an intermediate layer disposed between the solid electrolyte layer and the anode, the intermediate layer comprising cerium oxide; the anode comprising a nickel alloy and an oxide containing an alkaline earth metal; the nickel alloy comprising at least one metal selected from the group consisting of manganese, iron, cobalt, copper, and tin; and the ratio of the alkaline earth metal content to the nickel content in the anode is 5 mol % or more.

[0217] (Aspect 11) The solid oxide electrolysis cell according to aspect 10, wherein the oxide containing an alkaline earth metal includes an oxide of at least one metal selected from calcium, strontium, and barium.

[0218] (Aspect 12) A module having a plurality of solid oxide electrolysis cells, wherein at least one of the solid oxide electrolysis cells is the solid oxide electrolysis cell according to aspect 10 or 11.

[0219] (Aspect 13) A solid oxide electrolysis cell system comprising: the module according to Aspect 12; a power supply device that supplies power to the module; a gas supply device that supplies water vapor and / or carbon dioxide to the module; a gas separation device that separates hydrogen and / or carbon monoxide generated from the module; and a storage device that stores the hydrogen and / or carbon monoxide separated by the gas separation device.

[0220] This application claims priority based on Japanese Patent Application No. 2023-207541, filed on December 8, 2023, the entire contents of which are incorporated herein by reference.

[0221] REFERENCE SIGNS LIST 100 First cell (SOEC) 110 Anode 120 Oxide cathode 130 Solid electrolyte layer 150 First intermediate layer 160 Second intermediate layer 170 External power source 201 SOEC system 210 SOEC module 220 Power supply device 230 Gas supply device 240 Gas separation device 250 Storage device

Claims

1. An electrode material for a solid oxide electrolysis cell, comprising nickel oxide and a composite oxide, the composite oxide containing an alkaline earth metal element and at least one metal element selected from the group consisting of manganese, iron, cobalt, copper and tin.

2. The composite oxide has the general formula: ｘ M ｙ O ｚ 2. The electrode material according to claim 1, wherein x>0, y>0, z>0, A is at least one element selected from the group consisting of calcium, strontium, and barium, M is at least one element selected from the group consisting of manganese, iron, cobalt, copper, and tin, and 0.1≦x / y≦4.

3. The electrode material according to claim 1, wherein the composite oxide satisfies 0.5≦x / y≦2.

4. A powder comprising the electrode material according to claim 1.

5. The powder according to claim 4, wherein the nickel oxide has an average particle size of 0.1 μm or more and 10 μm or less.

6. The powder according to claim 4, wherein the composite oxide has an average particle size of 0.1 μm or more and 50 μm or less.

7. A paste comprising the powder according to claim 4.

8. A fuel electrode member for a solid oxide electrolysis cell comprising the electrode material according to claim 1.

9. A laminate for a solid oxide electrolysis cell, comprising: an anode member, an oxygen electrode, and a solid electrolyte layer between the anode member and the oxygen electrode, an intermediate layer is disposed between the solid electrolyte layer and the anode member, the intermediate layer comprising cerium oxide, and the anode member includes the electrode material according to claim 1.

10. A solid oxide electrolysis cell comprising: a fuel electrode, an oxygen electrode, and a solid electrolyte layer between the fuel electrode and the oxygen electrode; an intermediate layer is disposed between the solid electrolyte layer and the fuel electrode, the intermediate layer comprising cerium oxide; the fuel electrode comprises a nickel alloy and an oxide containing an alkaline earth metal, the nickel alloy comprising at least one metal selected from the group consisting of manganese, iron, cobalt, copper and tin; and in the fuel electrode, a ratio of the alkaline earth metal content to the nickel content is 5 mol % or more.

11. The solid oxide electrolysis cell of claim 10, wherein the oxide containing an alkaline earth metal includes an oxide of at least one metal selected from calcium, strontium, and barium.

12. A module having a plurality of solid oxide electrolysis cells, at least one of said solid oxide electrolysis cells being a solid oxide electrolysis cell according to claim 10.

13. A solid oxide electrolysis cell system comprising: a module according to claim 12; a power supply device that supplies power to the module; a gas supply device that supplies water vapor and / or carbon dioxide to the module; a gas separation device that separates hydrogen and / or carbon monoxide generated from the module; and a storage device that stores the hydrogen and / or carbon monoxide separated by the gas separation device.

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