Electrochemical elements, electrochemical modules, solid oxide fuel cells, solid oxide electrolytic cells, electrochemical devices, energy systems, and methods for manufacturing electrochemical elements.

Abstract

This method maintains electronic conductivity and oxygen reduction reactions while suppressing the decrease in gas diffusion performance due to sintering. [Solution] An electrochemical element in which an electrode layer 2, an electrolyte layer 4, and a counter electrode layer 6 are stacked in the order described, and the air electrode or oxygen generating electrode, which is either the electrode layer 2 or the counter electrode layer 6, has an active layer 6a in which an oxidation-reduction reaction is carried out from the side of the electrolyte layer 4 and a diffusion layer 6b for diffusing gas, wherein the diffusion layer 6b is composed of a mixture of particulate LSCF and CoMn metal oxide, which is a metal oxide containing particulate Co and Mn.

Description

Technical Field

[0001] The present invention relates to an electrochemical element, an electrochemical module, a solid oxide fuel cell, a solid oxide electrolysis cell, an electrochemical device, an energy system, and a method for manufacturing an electrochemical element in which an electrode layer, an electrolyte layer, and a counter electrode layer are laminated in this order.

Background Art

[0002] The electrodes used on the atmospheric side of solid oxide fuel cell stacks and solid oxide electrolysis cells (hereinafter, SOFC, SOEC) are the air electrode (cathode) in SOFC and the oxygen generation electrode (anode) in SOEC. When these electrodes are generally configured in a cell stack, they are composed of two layers, an active layer (the layer where the oxidation-reduction reaction of the electrode actually occurs) and a diffusion layer (gas diffusion and electronic conductivity) in order from the electrolyte side. In the active layer, since the oxidation-reduction reaction of oxygen occurs at the electrolyte interface and inside the electrode, fine particles are used for the purpose of increasing the length of the three-phase interface. Here, the three-phase interface may also be widened by compositing the same materials as the electrolyte, for example, GDC and LSCF.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The diffusion layer described above needs to be more porous than the active layer in order to improve gas diffusion (intrusion of air, i.e., oxygen, in the SOFC air electrode, and escape of oxygen in the SOEC oxygen generation electrode). Therefore, even if the same electrode material as the active layer is used, it is necessary to increase the porosity by increasing the particle size. However, it is known that LSCF particles undergo thermal sintering during SOFC / SOEC operation, which reduces the porosity of the diffusion layer and inhibits gas diffusion. This reduces the electrode performance on the atmospheric side and degrades the SOFC / SOEC cell stack. Therefore, in order to improve the durability of the diffusion layer of the air electrode used in metal-supported SOFC cell stacks (or the oxygen-evolving electrode used in SOEC cell stacks; hereafter, when describing the air electrode of SOFCs, the concept may also include the oxygen-evolving electrode of SOECs), materials or configurations that suppress sintering during operation are required.

[0005] The diffusion layer uses a material similar to the active layer of the air electrode (or, if the active layer is a composite, a perovskite-based material with GDC removed). When using perovskite-based materials, sintering is unavoidable, and measures such as lowering the operating temperature to slow down its progression or using coarse particles from the beginning can be considered. The former raises concerns about lower initial performance, while the latter carries the risk of cell delamination due to reduced adhesion. When using materials other than perovskite-based materials, porosity can be maintained without sintering by using spinel-type oxides in the diffusion layer, but the electronic conductivity is lower than that of perovskite-type oxides. Furthermore, since spinel-type oxides hardly produce oxygen vacancies, if the entire diffusion layer is made of spinel oxide, performance will deteriorate due to a decrease in electronic conductivity, and since oxygen reduction reactions hardly occur, oxygen adsorption and dissociation in the active layer do not occur, resulting in performance degradation.

[0006] The present invention has been made in view of the above-mentioned problems, and its objective is to provide an electrochemical element, an electrochemical module, a solid oxide fuel cell, a solid oxide electrolytic cell, an electrochemical device, an energy system, and a method for manufacturing an electrochemical element that can suppress the decrease in gas diffusion performance due to sintering while maintaining electronic conductivity and oxygen reduction reaction. [Means for solving the problem]

[0007] The electrochemical element for achieving the above objective is: The electrode layer, electrolyte layer, and counter electrode layer are stacked in the order described above. The electrochemical element, in which either the electrode layer or the counter electrode layer is an air electrode or an oxygen-generating electrode, has an active layer where an oxidation-reduction reaction takes place from the side of the electrolyte layer and a diffusion layer for diffusing gas, and its characteristic configuration is: The diffusion layer is composed of a mixture of particulate LSCF and CoMn metal oxide, which is a metal oxide containing particulate Co and Mn. Occasionally, The mass ratio of the LSCF in the diffusion layer is 60% by mass or more and 80% by mass or less. The mass percentage of the CoMn metal oxide in the diffusion layer is 40% by mass or less, and the sum of the mass percentages of the CoMn metal oxide and the LSCF is 100% or less. It's at a single point.

[0008] A method for manufacturing an electrochemical element to achieve the above objective is: The electrode layer, electrolyte layer, and counter electrode layer are stacked in the order described above. A method for manufacturing an electrochemical element in which either the electrode layer or the counter electrode layer, which is either an air electrode or an oxygen-generating electrode, has an active layer in which an oxidation-reduction reaction takes place from the side of the electrolyte layer and a diffusion layer for diffusing gas, wherein the characteristic configuration is: The process includes a diffusion layer sintering step in which a mixture of particulate LSCF and a CoMn metal oxide containing particulate Co and Mn is applied to the active layer as the diffusion layer and sintered. fruit, The mass ratio of the LSCF in the diffusion layer is 60% by mass or more and 80% by mass or less. The mass percentage of the CoMn metal oxide in the diffusion layer is 40% by mass or less, and the sum of the mass percentages of the CoMn metal oxide and the LSCF is 100% or less. It's at a single point.

[0009] The inventors have confirmed through tests described later that by using a mixture of particulate LSCF (perovskite oxide) and CoMn metal oxide (spinel oxide), which is a metal oxide containing particulate Co and Mn, as a diffusion layer, it is possible to maintain electronic conductivity and oxygen reduction reaction while suppressing the reduction in gas diffusion performance due to sintering, using LSCF (perovskite oxide) as the framework. As mentioned above, the reason why sintering can be suppressed is thought to be that in a mixture of particulate LSCF (perovskite-type oxide) and CoMn metal oxide (spinel-type oxide), which is a metal oxide containing particulate Co and Mn, the fine particles of CoMn connect the LSCF particles, reducing the contact area between the LSCF particles and thus maintaining porosity. Furthermore, according to the above characteristic configuration, LSCF particles are present in the diffusion layer, and since an oxygen reduction reaction (mainly oxygen adsorption and dissociation) occurs on the surface of the LSCF particles, this oxygen reduction reaction can also be generated in the diffusion layer. Furthermore, as described above, by setting the mass ratio of CoMn metal oxide in the diffusion layer to 40% by mass or less, sintering of LSCF particles and CoMn particles in the diffusion layer can be effectively suppressed, and the resistance can be made comparable to that when the diffusion layer is composed of LSCF alone, and the decrease in electronic conductivity can be sufficiently suppressed, as confirmed in subsequent tests. Based on the above, it is possible to realize an electrochemical element that can maintain electronic conductivity and oxygen reduction reaction while suppressing the decrease in gas diffusion performance due to sintering.

[0010] Further characteristic features of the electrochemical element are: The particle size of the particulate LSCF is larger than the particle size of the particulate CoMn metal oxide.

[0011] By configuring the material as described above, CoMn microparticles are more likely to be present between LSCF particles, making it easier to connect the LSCF particles with the CoMn microparticles, thereby better suppressing sintering and maintaining the porous state of the diffusion layer. The particle size was determined by magnified observation using a field emission scanning electron microscope (FE-SEM: JEOL JSM-7400F) at an acceleration voltage of 5kV, and is defined as the maximum length connecting one end of the particle to the other.

[0012]

[0013]

[0014]

[0015]

[0016] A further characteristic configuration of the electrochemical element is that the composition of the LSCF is La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3-δ and the composition of the CoMn metal oxide is at least one of Co 1.5 Mn 1.5 O4, Co2MnO4, Co 2.5 Mn 0.5 O4, and the ratio of La to Co in the diffusion layer mass is in the range of mass to 1.051 2.762 or more and 2.762 or less. However, δ is the amount of oxygen vacancies.

[0017] The ratio of La to Co in the diffusion layer mass is set to be in the range of mass 2.762 or more and 2.762 or less, so that the sintering of LSCF particles in the diffusion layer can be well suppressed, and it has been confirmed in later tests that the decrease in electronic conductivity can be suppressed with a resistance comparable to the case where the diffusion layer is composed of LSCF alone. 1.051

[0018] A further characteristic configuration of the electrochemical element is that the composition of the LSCF is La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3-δ and the composition of the CoMn metal oxide is at least one of Co 1.5 Mn 1.5 O4, Co2MnO4, Co 2.5 Mn 0.5 O4, and In the aforementioned diffusion layer, Mn mass La's mass The ratio 、4 .04 4 It lies at a certain point. However, δ is the amount of oxygen vacancies.

[0019] Mn in the diffusion layer mass La's mass The ratio 、4 .04 4 and Subsequent tests confirmed that this effectively suppresses sintering of LSCF particles in the diffusion layer, while also suppressing a decrease in electronic conductivity, resulting in a resistance comparable to that of a diffusion layer constructed solely from LSCF. Furthermore, although not within the scope of the rights of this application, electrochemical elements are Further characteristic features of the electrochemical element are: The composition of the aforementioned LSCF is La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3-δ And, The composition of the aforementioned CoMn metal oxide is Co 1.5 Mn 1.5 O 4 Co 2 MnO 4 Co 2.5 Mn 0.5 O 4 It is at least one of the following: The ratio of the weight of La to the weight of Co in the diffusion layer may be in the range of 0.216 to 2.762. However, δ is the amount of oxygen vacancies. By setting the ratio of La weight to Co weight in the diffusion layer to a range of 0.216 to 2.762, sintering of LSCF particles in the diffusion layer can be effectively suppressed, and the decrease in electronic conductivity can be suppressed, resulting in a resistance similar to that of a diffusion layer composed solely of LSCF. Although not within the scope of the rights of this application, electrochemical elements are The composition of the aforementioned LSCF is La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3-δ And, The composition of the aforementioned CoMn metal oxide is Co 1.5 Mn 1.5 O 4 Co 2 MnO 4 Co 2.5 Mn 0.5 O 4 It is at least one of the following: The ratio of the weight of La to the weight of Mn in the diffusion layer may be in the range of 0.250 to 4.044. However, δ is the amount of oxygen vacancies. By setting the ratio of La weight to Mn weight in the diffusion layer to a range of 0.250 to 4.044, sintering of LSCF particles in the diffusion layer can be effectively suppressed, and the decrease in electronic conductivity can be suppressed by maintaining a resistance similar to that of a diffusion layer composed solely of LSCF.

[0020] Further characteristic features of the electrochemical element are: The particle size of the LSCF is 0.20 μm or more and 0.50 μm or less. The particle size of the aforementioned CoMn metal oxide is between 0.10 μm and 0.19 μm.

[0021] As described above, by setting the particle size of LSCF and CoMn metal oxide as described above, sintering can be effectively prevented, gas diffusion in the diffusion layer can be improved, durability can be enhanced, and the electronic conductivity required for the diffusion layer can be effectively exhibited.

[0022] Further characteristic features of the manufacturing method for electrochemical elements are: The distinguishing feature is that it includes a pre-sintering step in which particulate LSCF is sintered before the diffusion layer sintering step.

[0023] According to the above characteristic configuration, particulate LSCF particles can be bonded together to form large-diameter LSCF particles, effectively suppressing sintering.

[0024] Further characteristic features of the manufacturing method for electrochemical elements are: The particle size of the LSCF after the pre-sintering step and before the diffusion layer sintering step is larger than the particle size of the CoMn metal oxide before the diffusion layer sintering step. The particle size of the particulate LSCF after the pre-sintering step and before the diffusion layer sintering step is 0.20 μm or more and 0.50 μm or less. The particle size of the particulate CoMn metal oxide before the diffusion layer sintering process is between 0.10 μm and 0.19 μm.

[0025] According to the above characteristic configuration, sintering can be effectively prevented, and gas diffusion in the diffusion layer can be improved, thereby enhancing durability and enabling the diffusion layer to exhibit the required electronic conductivity.

[0026] The characteristic configuration of the electrochemical module using the electrochemical elements described above is: The key feature is that multiple of the aforementioned electrochemical elements are connected and arranged in a bundled configuration.

[0027] According to the above characteristic configuration, by arranging multiple electrochemical elements in a clustered state, it is possible to achieve a relatively low-temperature firing process, and an electrochemical module that exhibits low resistance and high adhesion under operating conditions can be realized. Furthermore, for example, when the electrochemical module is operated as a fuel cell, it becomes possible to obtain a large power output.

[0028] The characteristic configuration of the solid oxide fuel cell using the electrochemical elements described above is: The key feature is generating electricity through the electrochemical elements mentioned above.

[0029] According to the above characteristic configuration, a solid oxide fuel cell equipped with the electrochemical elements described above can perform power generation reactions, thereby enabling the creation of a solid oxide fuel cell that maintains electronic conductivity and oxygen reduction reactions while suppressing the decrease in gas diffusion performance due to sintering.

[0030] The characteristic configuration of the solid oxide type electrolytic cell using the electrochemical elements described above is: The key feature is that it generates an electrolytic reaction using the aforementioned electrochemical elements.

[0031] According to the above characteristic configuration, a solid oxide type electrolytic cell equipped with the electrochemical elements described above can generate gas through an electrolytic reaction. Therefore, a solid oxide type electrolytic cell can be obtained that maintains electronic conductivity and oxygen reduction reaction while suppressing the decrease in gas diffusion performance due to sintering.

[0032] The characteristic configuration of the electrochemical apparatus using the electrochemical module described above is: The above-mentioned electrochemical module and fuel converter are included, The present invention has an electrochemical module and a fuel converter as described in claim 7, and a fuel supply unit that supplies a reducing component gas from the fuel converter to the electrochemical element or the electrochemical module, or supplies a reducing component gas from the electrochemical element or the electrochemical module to the fuel converter.

[0033] According to the above-described configuration, when an electrochemical element or electrochemical module is operated as a fuel cell, it is possible to configure it to generate hydrogen using natural gas supplied via existing raw material supply infrastructure such as city gas, and then use a fuel converter such as a reformer. This allows for the realization of an electrochemical device equipped with an electrochemical element or electrochemical module that maintains electronic conductivity and oxygen reduction reaction while suppressing the decrease in gas diffusion performance due to sintering. Furthermore, it becomes easier to construct a system for recycling unused fuel gas distributed from the electrochemical module, thus enabling the realization of a highly efficient electrochemical device. On the other hand, when an electrochemical element or electrochemical module is operated as an electrolytic cell, a gas containing water vapor or carbon dioxide is passed through the electrode layer, and a voltage is applied between the electrode layer and the counter electrode layer. In this case, electrons e are generated in the electrode layer. - Water (H2O) and carbon dioxide molecules (CO2) react with hydrogen (H2), carbon monoxide (CO), and oxygen ions (O). 2- This results in the generation of oxygen ions O 2- It moves through the electrolyte layer to the counter electrode layer. Then, in the counter electrode layer, oxygen ions O 2-The gas releases electrons to become oxygen (O2). Through the above reaction, if a gas containing water vapor is in circulation, water (H2O) is decomposed into hydrogen (H2) and oxygen (O2), and if a gas containing carbon dioxide molecules (CO2) is in circulation, it is electrolyzed into carbon monoxide (CO) and oxygen (O2). Therefore, when a gas containing water vapor and carbon dioxide molecules (CO2) is circulated, a fuel converter can be provided that synthesizes various compounds such as hydrocarbons from hydrogen and carbon monoxide generated by the electrochemical element or electrochemical module through the electrolysis described above. This makes it possible to circulate the hydrocarbons generated by the fuel converter to the electrochemical element or electrochemical module, or to extract them outside the system / device and use them separately as fuel or chemical raw materials.

[0034] The characteristic configuration of the electrochemical apparatus using the electrochemical module described above is: The electrochemical module mentioned above, The key feature is that it includes at least a power converter that extracts power from the electrochemical element or the electrochemical module, or that supplies power to the electrochemical element or the electrochemical module.

[0035] According to the above characteristic configuration, the power converter can extract the electricity generated by the electrochemical element or electrochemical module, or supply electricity to the electrochemical element or electrochemical module. As a result, the electrochemical element or electrochemical module acts as a fuel cell or as an electrolytic cell, as described above. Therefore, according to the above characteristic configuration, an electrochemical device with improved efficiency in converting chemical energy such as fuel into electrical energy, or electrical energy into chemical energy such as fuel, can be realized while maintaining electronic conductivity and oxygen reduction reaction, and while suppressing the decrease in gas diffusion performance due to sintering suppression. Furthermore, for example, when an inverter is used as a power converter, it is preferable when operating as a fuel cell because the inverter can boost the voltage or convert DC to AC, making it easier to utilize the electrical output obtained from the electrochemical element or electrochemical module. Also, when operating as an electrolytic cell, it is preferable to construct an electrochemical device that can obtain DC from an AC power source and supply DC power to the electrochemical element or electrochemical module.

[0036] The characteristic configuration of the energy system using the electrochemical apparatus described above is: The electrochemical apparatus described above, The distinguishing feature is that it includes at least a waste heat utilization unit that reuses the heat discharged from the electrochemical apparatus.

[0037] According to the above-described configuration, it is possible to realize an energy system that is CO-free, economically superior, and highly energy-efficient. Furthermore, it is possible to realize an energy-efficient hybrid system by combining it with a power generation system that generates electricity using the combustion heat of unused fuel gas emitted from electrochemical equipment. [Brief explanation of the drawing]

[0038] [Figure 1] This is a schematic diagram of the electrochemical module. [Figure 2] This diagram shows the components that make up an electrochemical module. [Figure 3] This graph shows the ASR for each temperature in the examples and comparative examples. [Figure 4] This is a cross-sectional SEM image of the portion of the electrochemical module containing the bonding material of Comparative Example 1 immediately after manufacturing. [Figure 5]This is a cross-sectional SEM image of the portion of the electrochemical module according to Example 1, including the bonding material, immediately after manufacturing. [Figure 6] This is a cross-sectional SEM image of the portion of the electrochemical module according to Example 2, including the bonding material, immediately after manufacturing. [Figure 7] This is a cross-sectional SEM image of the portion of the electrochemical module containing the bonding material in Comparative Example 2 immediately after manufacturing. [Figure 8] This is a cross-sectional SEM image of the portion of the electrochemical module containing the bonding material of Comparative Example 3 immediately after manufacturing. [Figure 9] This is a cross-sectional SEM image of the portion of the electrochemical module containing the bonding material in Comparative Example 1 after temperature acceleration. [Figure 10] This is a cross-sectional SEM image of the portion of the electrochemical module according to Example 1, including the bonding material, after temperature acceleration. [Figure 11] This is a cross-sectional SEM image of the portion of the electrochemical module according to Example 2, including the bonding material, after temperature acceleration. [Figure 12] This is a cross-sectional SEM image of the portion of the electrochemical module containing the bonding material in Comparative Example 2 after temperature acceleration. [Figure 13] This is a cross-sectional SEM image of the portion of the electrochemical module containing the bonding material in Comparative Example 3 after temperature acceleration. [Figure 14] This diagram shows the configuration of an energy system and an electrochemical apparatus. [Figure 15] This diagram shows the configuration of an energy system and an electrochemical apparatus. [Modes for carrying out the invention]

[0039] The electrochemical elements, electrochemical modules, solid oxide fuel cells, solid oxide electrolytic cells, electrochemical devices, energy systems, and methods for manufacturing electrochemical elements according to the embodiment are capable of firing at relatively low temperatures and achieving low resistance and high adhesion under operating conditions. The following describes, based on the drawings, an electrochemical element, an electrochemical module, a solid oxide fuel cell, a solid oxide electrolytic cell, an electrochemical device, an energy system, and a method for manufacturing an electrochemical element according to the embodiment.

[0040] Figure 1 shows the configuration of an electrochemical module M. Figure 2 is a diagram illustrating the components that make up the electrochemical module M. As shown in the figures, the electrochemical module M comprises an alloy member 26, electrochemical elements E, and a joining material 10 that joins the alloy member 26 (an example of an inter-cell connecting member) and the electrochemical elements E. In particular, the electrochemical module M shown in Figure 1 comprises a plurality of electrochemical elements E, and the plurality of electrochemical elements E are electrically connected to each other by the alloy member 26. In this specification, the term "inter-cell connecting member" refers to interconnectors, separators, current collectors, etc.

[0041] The electrochemical element E has a single cell C in which an electrolyte layer 4 is sandwiched between an electrode layer 2 and a counter electrode layer 6. In this embodiment, the electrochemical element E has a single cell C on a metal support (metal substrate) 1 having through holes 1a. The single cell C in this embodiment comprises an electrode layer 2, an intermediate layer 3, an electrolyte layer 4, a reaction prevention layer (intermediate layer) 5, and a counter electrode layer 6.

[0042] The electrochemical element E is used, for example, as a component of a solid oxide fuel cell that generates electricity by receiving a hydrogen-containing fuel gas and air. When explaining the positional relationship of the layers, for example, the side of the counter electrode layer 6 viewed from the electrolyte layer 4 may be called "upper" or "upper side," and the side of the electrode layer 2 may be called "lower" or "lower side." Also, the side of the metal support 1 on which the electrode layer 2 is formed may be called the front side, and the opposite side may be called the back side.

[0043] The electrochemical element E comprises a metal support 1, an electrode layer 2 formed on the metal support 1, an intermediate layer 3 formed on the electrode layer 2, an electrolyte layer 4 formed on the intermediate layer 3, a reaction prevention layer 5 formed on the electrolyte layer 4, and a counter electrode layer 6 formed on the reaction prevention layer 5. In other words, the counter electrode layer 6 is formed on the electrolyte layer 4, and the reaction prevention layer 5 is formed between the electrolyte layer 4 and the counter electrode layer 6. For example, the electrode layer 2 is porous, and the electrolyte layer 4 is dense.

[0044] The metal support 1 supports the single cell C, which is composed of an electrolyte layer 4 sandwiched between an electrode layer 2 and a counter electrode layer 6, thereby maintaining the strength of the electrochemical element E. In other words, the metal support 1 plays the role of a support for the electrochemical element E.

[0045] The material used for the metal support 1 is one that exhibits excellent electronic conductivity, heat resistance, oxidation resistance, and corrosion resistance. For example, ferritic stainless steel, austenitic stainless steel, and nickel-based alloys are used, but are not limited to these. In particular, alloys containing Cr are preferably used. In this embodiment, the material for the metal support 1 is an Fe-Cr alloy containing 18% to 25% by mass of Cr, but it is preferable to contain 0.05% or more by mass of Mn, and it is preferable to contain 0.05% to 1.0% by mass of Ni. Furthermore, for Cu, the lower limit is preferably 0.01% or more by mass, more preferably 0.10% or more by mass, and even more preferably 0.20% or more by mass, and the upper limit is preferably 1.0% or less by mass, more preferably 0.9% or less by mass, and even more preferably 0.8% or less by mass. Furthermore, the lower limit of the Ti content is preferably 0.05% by mass or more, more preferably 0.10% by mass or more, and even more preferably 0.15% by mass or more. The upper limit is preferably 1.0% by mass or less, more preferably 0.9% by mass or less, and even more preferably 0.8% by mass or less. By using such an Fe-Cr alloy, it is possible to use an alloy member with excellent performance, durability, and corrosion resistance as the metal support 1 while suppressing costs.

[0046] The metal support 1 is plate-shaped overall. The metal support 1 has a front surface on which the electrode layer 2 is provided, and has multiple through holes 1a that penetrate between the front surface and the back surface. The through holes 1a have the function of allowing gas to pass through between the front and back surfaces of the metal support 1. This allows for the smooth supply of fuel gas and oxidizer gas from the back surface of the metal support 1 to the electrode layer 2, thereby realizing a high-performance electrochemical element E. It is also possible to bend the plate-shaped metal support 1 to deform it into shapes such as a box or cylinder for use.

[0047] The electrode layer 2 can be provided as a thin layer on the surface of the metal support 1 so as to cover the through-hole 1a of the metal support 1. When it is a thin layer, its thickness can be, for example, about 1 μm to 100 μm, preferably 5 μm to 50 μm. With such a thickness, it is possible to reduce the amount of expensive electrode layer 2 material used, thereby lowering costs, while ensuring sufficient electrode performance.

[0048] For the electrode layer 2, composite materials such as NiO-GDC, Ni-GDC, NiO-YSZ, Ni-YSZ, CuO-CeO2, and Cu-CeO2 can be used. In these examples, GDC, YSZ, and CeO2 can be called aggregates of the composite material. The electrode layer 2 is preferably formed by a low-temperature firing method (for example, a wet method using firing in a low temperature range without firing in a high temperature range higher than 1100°C), a spray coating method (such as thermal spraying, aerosol deposition, aerosol gas deposition, powder jet deposition, particle jet deposition, and cold spray), a PVD method (such as sputtering and pulsed laser deposition), or a CVD method.

[0049] The electrode layer 2 has multiple pores on its interior and surface to allow gas permeability. In other words, electrode layer 2 is formed as a porous layer. Electrode layer 2 is formed such that, for example, its density is between 30% and 80%. The size of the pores can be appropriately selected to ensure smooth reaction during electrochemical reactions. Density is the ratio of the material constituting the layer to the surrounding space, and can be expressed as (1 - porosity), and is equivalent to relative density.

[0050] The intermediate layer 3 can be formed as a thin layer on the electrode layer 2. When forming a thin layer, its thickness can be, for example, about 1 μm to 100 μm, preferably about 2 μm to 50 μm, and more preferably about 4 μm to 25 μm. Such a thickness makes it possible to reduce the amount of expensive intermediate layer material used, thereby lowering costs while ensuring sufficient performance. As the material for the intermediate layer 3, for example, YSZ (yttria-stabilized zirconia), SSZ (scandium-stabilized zirconia), GDC (gadolinium-doped ceria), YDC (yttrium-doped ceria), SDC (samarium-doped ceria), etc. Ceria-based ceramics are particularly preferred.

[0051] The intermediate layer 3 is preferably formed by low-temperature firing (for example, a wet method using firing in a low temperature range without firing in a high temperature range higher than 1100°C), spray coating (such as thermal spraying, aerosol deposition, aerosol gas deposition, powder jet deposition, particle jet deposition, and cold spray), PVD (such as sputtering and pulsed laser deposition), or CVD. These film formation processes, which can be used in low temperature ranges, allow for the acquisition of the intermediate layer 3 without using firing in a high temperature range higher than 1100°C.

[0052] The intermediate layer 3 preferably has oxygen ion (oxide ion) conductivity. It is even more preferable if it has mixed conductivity between oxygen ions (oxide ions) and electrons. An intermediate layer 3 having these properties is suitable for application to an electrochemical element E.

[0053] The electrolyte layer 4 is formed as a thin layer on top of the intermediate layer 3. It can also be formed as a thin film with a thickness of 10 μm or less.

[0054] The materials for the electrolyte layer 4 include YSZ (yttria-stabilized zirconia), SSZ (scandium-stabilized zirconia), GDC (gadolinium-doped ceria), YDC (yttrium-doped ceria), SDC (samarium-doped ceria), LSGM (strontium-magnesium-doped lanthanum gallate), and LSO (lanthanum silicate, La 9.33+x Si6O 26+2x / 3 Electrolyte materials that conduct oxygen ions, such as ) and electrolyte materials that conduct hydrogen ions, such as perovskite-type oxides, can be used. Zirconia-based ceramics are particularly preferred. If the electrolyte layer 4 is made of zirconia-based ceramics, the operating temperature of the SOFC using the electrochemical element E can be made higher compared to ceria-based ceramics and various hydrogen ion conductive materials. For example, when using the electrochemical element E in an SOFC, if the electrolyte layer 4 is made of a material such as YSZ that can exhibit high electrolyte performance even in high temperature ranges of around 650°C or higher, and the system uses hydrocarbon-based raw fuels such as city gas or LPG as the raw fuel, and the raw fuel is converted into the anode gas of the SOFC by steam reforming, a highly efficient SOFC system can be constructed that uses the heat generated in the SOFC cell stack to reform the raw fuel gas.

[0055] The electrolyte layer 4 is preferably formed by low-temperature firing (for example, a wet method using firing in a low temperature range without firing in a high temperature range exceeding 1100°C), spray coating (such as thermal spraying, aerosol deposition, aerosol gas deposition, powder jet deposition, particle jet deposition, and cold spray), PVD (such as sputtering and pulsed laser deposition), or CVD. These film formation processes, usable in low temperature ranges, allow for the creation of a dense, airtight, and highly gas-barrier electrolyte layer 4 without using firing in a high temperature range exceeding 1100°C. In particular, using low-temperature firing or spray coating is preferable because it enables the realization of low-cost devices. Furthermore, using spray coating is even preferable because a dense, airtight, and highly gas-barrier electrolyte layer 4 can be easily obtained in a low temperature range.

[0056] The electrolyte layer 4 is densely constructed to shield against gas leaks of anode and cathode gases and to exhibit high ionic conductivity. The density of the electrolyte layer 4 is preferably 90% or higher, more preferably 95% or higher, and even more preferably 98% or higher. If the electrolyte layer 4 is a uniform layer, its density is preferably 95% or higher, and more preferably 98% or higher. Furthermore, if the electrolyte layer 4 is composed of multiple layers, it is preferable that at least a portion of it includes a layer with a density of 98% or higher (a dense electrolyte layer), and more preferably a layer with a density of 99% or higher (a dense electrolyte layer). This is because including such a dense electrolyte layer as part of the electrolyte layer 4 makes it easier to form a dense electrolyte layer 4 with high airtightness and gas barrier properties, even when the electrolyte layer 4 is composed of multiple layers.

[0057] The reaction prevention layer 5 can be formed as a thin layer on the electrolyte layer 4. When forming a thin layer, its thickness can be, for example, about 1 μm to 100 μm, preferably about 2 μm to 50 μm, and more preferably about 3 μm to 15 μm. By using such a thickness, it is possible to reduce the amount of expensive reaction prevention layer material used, thereby lowering costs while ensuring sufficient performance.

[0058] The reaction prevention layer 5 can be made of any material capable of preventing the reaction between the components of the electrolyte layer 4 and the components of the counter electrode layer 6, such as ceria-based materials. Preferably, the reaction prevention layer 5 is made of a material containing at least one element selected from the group consisting of Sm, Gd, and Y. It is preferable that the material contains at least one element selected from the group consisting of Sm, Gd, and Y, and that the total content of these elements is between 1.0% by mass and 10% by mass. By introducing the reaction prevention layer 5 between the electrolyte layer 4 and the counter electrode layer 6, the reaction between the constituent materials of the counter electrode layer 6 and the constituent materials of the electrolyte layer 4 is effectively suppressed, improving the long-term stability of the performance of the electrochemical element E. It is preferable to form the reaction prevention layer 5 using a method that can be performed at a processing temperature of 1100°C or lower, as this suppresses damage to the metal support 1 and also suppresses elemental diffusion between the metal support 1 and the electrode layer 2, thereby realizing an electrochemical element E with excellent performance and durability. For example, the process can be carried out using appropriate methods such as low-temperature firing (e.g., a wet method using firing in a low temperature range without firing in a high temperature range exceeding 1100°C), spray coating (such as thermal spraying, aerosol deposition, aerosol gas deposition, powder jet deposition, particle jet deposition, and cold spray), PVD (such as sputtering and pulsed laser deposition), and CVD. In particular, low-temperature firing and spray coating methods are preferable because they enable the realization of low-cost devices. Furthermore, using low-temperature firing is even preferable because it simplifies the handling of raw materials.

[0059] The counter electrode layer 6 can be formed as a thin layer on top of the reaction prevention layer 5. If the reaction prevention layer 5 is not provided, the counter electrode layer 6 is formed on top of the electrolyte layer 4. When it is a thin layer, its thickness can be, for example, about 1 μm to 100 μm, preferably 5 μm to 50 μm. Such a thickness makes it possible to reduce the amount of expensive counter electrode layer material used, thereby lowering costs while ensuring sufficient electrode performance. As the material for the counter electrode layer 6, at least a mixture of particulate LSCF and CoMn metal oxide, which is a metal oxide containing particulate Co and Mn, is used. Other materials that can be used include, for example, composite oxides such as LSM, ceria oxides, and mixtures thereof. In particular, the counter electrode layer 6 contains a perovskite-type oxide containing two or more elements selected from the group consisting of La, Sr, Sm, Mn, Co, and Fe. The counter electrode layer 6 constructed using the above materials functions as a cathode.

[0060] Furthermore, it is preferable to form the counter electrode layer 6 using a method that can be performed at a processing temperature of 1100°C or lower, as this suppresses damage to the metal support 1 and inhibits elemental diffusion between the metal support 1 and the electrode layer 2, thereby realizing an electrochemical element E with excellent performance and durability. For example, this can be done using a low-temperature firing method (e.g., a wet method using firing in a low temperature range without firing in a high temperature range exceeding 1100°C), a spray coating method (such as thermal spraying, aerosol deposition, aerosol gas deposition, powder jet deposition, particle jet deposition, or cold spray), a PDV method (such as sputtering or pulsed laser deposition), or a CVD method as appropriate. In particular, using a low-temperature firing method or a spray coating method is preferable because it enables the realization of a low-cost element. Moreover, using a low-temperature firing method is even preferable because it simplifies the handling of raw materials.

[0061] By configuring the electrochemical element E as described above, the electrochemical element E can be used as a power generation cell for a solid oxide fuel cell. For example, a fuel gas containing hydrogen is flowed from the back surface of the metal support 1 through the through hole 1a to the electrode layer 2, and air is flowed to the counter electrode layer 6 which is the opposite electrode of the electrode layer 2, and the device is operated at a temperature of, for example, 500°C to 900°C. In this case, oxygen O2 contained in the air in the counter electrode layer 6 will produce electrons e - It reacts with oxygen ions O 2- This is produced. The oxygen ion O 2- The hydrogen (H2) contained in the supplied fuel gas moves through the electrolyte layer 4 to the electrode layer 2. In the electrode layer 2, the hydrogen (H2) is replaced by oxygen ions (O2). 2- It reacts with water (H2O) and electrons (e). - When an electrolyte material that conducts hydrogen ions is used in the electrolyte layer 4, the hydrogen H2 contained in the fuel gas flowing through the electrode layer 2 is converted into electrons e. - It releases hydrogen ions H + This generates hydrogen ions H + The oxygen (O2) and hydrogen ions (H) contained in the air move through the electrolyte layer 4 to the counter electrode layer 6. + , electronic e - These react to produce water (H2O). The above reaction generates an electromotive force between electrode layer 2 and counter electrode layer 6. In this case, electrode layer 2 functions as the fuel electrode (anode) of the SOFC, and counter electrode layer 6 functions as the air electrode (cathode). In this way, a solid oxide fuel cell equipped with an electrochemical module M that generates electricity in a single cell C is realized.

[0062] Now, as shown in Figure 2, the counter electrode layer 6, which serves as the air electrode (cathode) in this embodiment, has an active layer 6a where the oxidation-reduction reaction takes place from the side of the electrolyte layer 4, and a diffusion layer 6b for diffusing gas. The diffusion layer 6b is composed of a mixture of particulate LSCF and CoMn metal oxide, which is a metal oxide containing particulate Co and Mn.

[0063] In the initial stages of its manufacturing, the electrochemical element E is composed of particulate LSCF particles with a larger particle size than particulate CoMn metal oxide particles. More specifically, the particle size of the LSCF is preferably between 0.20 μm and 0.50 μm, and the particle size of the CoMn metal oxide is preferably between 0.10 μm and 0.19 μm.

[0064] Furthermore, in the initial stages of manufacturing the electrochemical element E, in order to effectively suppress sintering of LSCF particles in the diffusion layer 6b and sufficiently suppress the decrease in electronic conductivity, the LSCF in the diffusion layer 6b mass When the proportion is 20% by mass or more and 80% by mass or less, the CoMn metal oxide in the diffusion layer 6b mass The proportion is preferably 80% by mass or less, and more preferably 40% by mass or less.

[0065] Furthermore, with respect to the diffusion layer 6b, in the initial stages of manufacturing the electrochemical element E, the composition of LSCF is La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3-δ The composition of the CoMn metal oxide is Co 1.5 Mn 1.5 O4, Co2MnO4, Co 2.5 Mn 0.5 It is at least one of O4, and the Co in the diffusion layer 6b mass La's mass The ratio of 1.051 Preferably, the value is within the range of 2.762 or less. However, δ is the amount of oxygen vacancies. Furthermore, the amount of Mn in the diffusion layer 6b mass La's mass The ratio 、4 .04 4 It is preferable that this be the case, where δ is the amount of oxygen vacancies.

[0066] The method for manufacturing the counter electrode layer 6, which serves as the air electrode (cathode) of the electrochemical element as described above, includes a diffusion layer sintering step in which a mixture of particulate LSCF and CoMn metal oxide, which is a metal oxide containing particulate Co and Mn, is applied to the active layer 6a as a diffusion layer 6b and sintered.

[0067] Furthermore, in the manufacturing method of the counter electrode layer 6 as an air electrode (cathode), it is preferable to include a pre-sintering step in which particulate LSCF is sintered before the diffusion layer sintering step. By performing this pre-sintering step, the LSCF particles can be condensed together to form large-diameter LSCF particles. In this process, the temperature at which the LSCF is sintered to increase its diameter during the pre-sintering step is preferably between 1000°C and 1500°C, and more preferably between 1200°C and 1400°C. Furthermore, the temperature at which the LSCF and CoMn metal oxide are sintered in the diffusion layer sintering process is preferably between 700°C and 900°C, and more preferably between 750°C and 850°C.

[0068] Here, it is preferable that the particle size of LSCF after the pre-sintering process and before the diffusion layer sintering process be larger than the particle size of CoMn metal oxide before the diffusion layer sintering process, and it is preferable that the particle size of particulate LSCF after the pre-sintering process and before the diffusion layer sintering process is 0.20 μm or more and 0.50 μm or less, and the particle size of particulate CoMn metal oxide before the diffusion layer sintering process is 0.10 μm or more and 0.19 μm or less.

[0069] Next, we will explain the manufacturing method of the electrochemical module M.

[0070] In the electrode layer formation step, the electrode layer 2 is formed as a thin film on the metal support 1. As described above, the electrode layer 2 can be formed using methods such as low-temperature firing (wet firing method at a low temperature of 1100°C or below), spray coating (thermal spraying, aerosol deposition, aerosol gas deposition, powder jet deposition, particle jet deposition, cold spray, etc.), PVD (sputtering, pulsed laser deposition, etc.), and CVD. In any case, it is desirable to perform the process at a temperature of 1100°C or below to suppress deterioration of the metal support 1.

[0071] When the electrode layer formation step is performed by a low-temperature firing method, it is carried out specifically as shown in the following example. First, a material paste is created by mixing the material powder for electrode layer 2 with a solvent (dispersion medium) and applied to the front surface of the metal support 1. Then, electrode layer 2 is compression molded (electrode layer smoothing step) and fired at a temperature of 1100°C or lower (electrode layer firing step). Compression molding of electrode layer 2 can be performed by methods such as CIP (Cold Isostatic Pressing), roll press molding, or RIP (Rubber Isostatic Pressing). Firing of electrode layer 2 is preferably performed at a temperature between 800°C and 1100°C. The order of the electrode layer smoothing step and the electrode layer firing step can also be reversed. Furthermore, when forming an electrochemical element E having an intermediate layer 3, the electrode layer smoothing step and the electrode layer firing step can be omitted, or the electrode layer smoothing step and the electrode layer firing step can be included in the intermediate layer smoothing step and the intermediate layer firing step described later. The electrode layer smoothing step can also be performed by lapping, leveling, surface cutting, polishing, etc.

[0072] In the intermediate layer formation step, an intermediate layer 3 is formed on top of the electrode layer 2 in a thin layer, covering the electrode layer 2. As described above, the intermediate layer 3 can be formed using methods such as low-temperature firing (wet firing method at low temperatures of 1100°C or below), spray coating (thermal spraying, aerosol deposition, aerosol gas deposition, powder jet deposition, particle jet deposition, cold spray, etc.), PVD (sputtering, pulsed laser deposition, etc.), and CVD. In any case, it is desirable to perform the process at a temperature of 1100°C or below in order to suppress the deterioration of the metal support 1.

[0073] When the intermediate layer formation step is performed using a low-temperature firing method, it is carried out specifically as shown in the following example. First, a material paste is prepared by mixing the material powder of the intermediate layer 3 with a solvent (dispersion medium) and applied to the front surface of the metal support 1. Then, the intermediate layer 3 is compression molded (intermediate layer smoothing step) and fired at 1100°C or below (intermediate layer firing step). The rolling of the intermediate layer 3 can be carried out by methods such as CIP (Cold Isostatic Pressing), roll press molding, or RIP (Rubber Isostatic Pressing). Furthermore, it is preferable to fire the intermediate layer 3 at a temperature between 800°C and 1100°C. This is because at such temperatures, a high-strength intermediate layer 3 can be formed while suppressing damage and deterioration of the metal support 1. It is even more preferable to fire the intermediate layer 3 at 1050°C or below, and even more preferable to fire it at 1000°C or below. This is because the lower the firing temperature of the intermediate layer 3, the more effectively damage and deterioration of the metal support 1 can be suppressed while forming the electrochemical element E. Furthermore, the order of the intermediate layer smoothing process and the intermediate layer firing process can be reversed. The intermediate layer smoothing process can also be performed by methods such as lapping, leveling, or surface cutting and polishing.

[0074] In the electrolyte layer formation step, the electrolyte layer 4 is formed as a thin layer on the intermediate layer 3, covering the electrode layer 2 and the intermediate layer 3. Alternatively, it may be formed as a thin film with a thickness of 10 μm or less. As described above, the electrolyte layer 4 can be formed using methods such as low-temperature firing (wet firing method at a low temperature of 1100°C or less), spray coating (thermal spraying, aerosol deposition, aerosol gas deposition, powder jet deposition, particle jet deposition, cold spray, etc.), PVD (sputtering, pulsed laser deposition, etc.), and CVD. In any case, it is desirable to perform the process at a temperature of 1100°C or less to suppress deterioration of the metal support 1.

[0075] In order to form a high-quality electrolyte layer 4 that is dense, airtight, and has excellent gas barrier properties at a temperature of 1100°C or lower, it is desirable to perform the electrolyte layer formation step by spray coating. In this case, the material for the electrolyte layer 4 is sprayed toward the intermediate layer 3 on the metal support 1 to form the electrolyte layer 4.

[0076] In the reaction prevention layer formation step, the reaction prevention layer 5 is formed as a thin layer on the electrolyte layer 4. As described above, the reaction prevention layer 5 can be formed using methods such as low-temperature firing (wet firing method in a low-temperature range of 1100°C or lower), spray coating (thermal spraying, aerosol deposition, aerosol gas deposition, powder jet deposition, particle jet deposition, cold spray, etc.), PVD (sputtering, pulsed laser deposition, etc.), and CVD. Regardless of the method used, it is desirable to carry out the process at a temperature of 1100°C or lower in order to suppress deterioration of the metal support 1. In addition, in order to flatten the upper surface of the reaction prevention layer 5, for example, leveling treatment or surface cutting and polishing treatment may be performed after the formation of the reaction prevention layer 5, or press processing may be performed after wet formation and before firing.

[0077] In the counter electrode layer formation step, the counter electrode layer 6 is formed as a thin layer on the reaction prevention layer 5. As described above, the counter electrode layer 6 can be formed using methods such as low-temperature firing (wet firing method at a low temperature of 1100°C or lower), spray coating (thermal spraying, aerosol deposition, aerosol gas deposition, powder jet deposition, particle jet deposition, cold spray, etc.), PVD (sputtering, pulsed laser deposition, etc.), and CVD. In any case, it is desirable to perform the process at a temperature of 1100°C or lower to suppress deterioration of the metal support 1.

[0078] As described above, an electrochemical module M can be fabricated as shown in Figures 1 and 2 by sequentially joining the electrochemical element E and the alloy member 26 in series using the bonding material 10. Specifically, the counter electrode layer 6 of the electrochemical element E and the alloy member 26 are joined using the bonding material 10. In addition, a U-shaped member 9 is joined to the back side of the metal support 1 of the electrochemical element E, and the alloy member 26 is joined to the U-shaped member 9. In other words, the alloy member 26 is joined to the counter electrode layer 6 of the electrochemical element E and the U-shaped member 9, electrically connecting the two. A cylindrical support is formed by the metal support 1 and the U-shaped member 9. Gas flowing through the internal space of the cylindrical support is supplied to the electrode layer 2 through the through hole 1a of the metal support 1. It is preferable that the material of the U-shaped member 9 is the same metallic material as the metal support 1, from the viewpoint of reducing the difference in thermal expansion with the metal support 1 and ensuring the reliability of the joint, such as welding.

[0079] The alloy member 26 is made of a material containing Fe and Cr. For example, the alloy member 26 can be made of ferritic stainless steel, Fe-Cr-Ni alloy which is an austenitic stainless steel with superior heat resistance, or a nickel-based alloy. It is preferable that the material of the alloy member 26 is the same as that of the metal support 1, from the viewpoint of reducing the difference in thermal expansion with the metal support 1.

[0080] The manufacturing method of the electrochemical module M of this embodiment will now be described. As shown in Figure 1, each of the multiple electrochemical elements E is stacked and arranged such that it faces an alloy member 26 on the counter electrode layer 6 side via a bonding material 10, and faces another alloy member 26 on the metal support 1 side via a U-shaped member 9. As part of the manufacturing method of the electrochemical module M, a bonding process is performed in which the bonding material 10 is placed between the alloy member 26 and the electrochemical element E and fired at a temperature of less than 1000°C. For example, a joining process is performed in which a paste containing material fine particles of the joining material 10 is placed between the alloy member 26 and the electrochemical element E and fired. As a result, the alloy member 26 and the electrochemical element E can be joined using the joining material 10 to join the two. In addition, the firing temperature in the joining process is more preferably 900°C or lower, and even more preferably 800°C or lower, as a lower firing temperature reduces the damage to the electrochemical module M. Furthermore, in order to ensure good bonding performance, the firing temperature is preferably 600°C or higher, more preferably 650°C or higher, and even more preferably 700°C or higher.

[0081] The bonding material 10 is preferably a material containing Co. Alternatively, the bonding material 10 is preferably a material containing Ni. Alternatively, the bonding material 10 is preferably a material containing a metal oxide containing at least two of Co, Mn, Cu, and Ni. Furthermore, the bonding material 10 has a structure in which a plurality of fine particles are aggregated, with an average particle size of 0.1 μm or more and 0.2 μm or less when the alloy member 26 and the single cell C of the electrochemical element E are bonded together. In addition, the bonding material 10 is preferably 60% or more in void ratio when the alloy member 26 and the single cell C of the electrochemical element E are bonded together. Furthermore, it is even more preferable that the void ratio be 65% or more. The thickness of the bonding material 10 is not particularly limited, but from the viewpoint of cost-effectiveness, it is preferably 1 μm or more, more preferably 5 μm or more, even more preferably 10 μm or more, preferably 300 μm or less, more preferably 200 μm or less, and even more preferably 100 μm or less.

[0082] Next, we will explain the test results related to the counter electrode layer 6, which serves as the air electrode (cathode). The diffusion layer 6b of the counter electrode layer 6, which served as the air electrode (cathode) used in this test, is LSCF (La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3-δ ) and CoMn(Co 1.5 Mn 1.5 A mixture of O4) (where δ is the amount of oxygen vacancies), Example 1 contains 80% by mass of LSCF and 20% by mass of CoMn, and Example 2 contains 60% by mass of LSCF and 40% by mass of CoMn. Comparative Example 2 However, it contains 40% by mass of LSCF and 60% by mass of CoMn. Comparative Example 3 However, the comparative example contains 20% by mass of LSCF and 80% by mass of CoMn, while the comparative example contains 100% by mass of LSCF.

[0083] Figure 3 shows the relationship between temperature and ASR (Area Specific Resistance). Furthermore, the ASR of the diffusion layer 6b of the air electrode (cathode) was measured by measuring the voltage drop at the junction under a constant current using the four-terminal method. As shown in Figure 3, Example 1 、2 and comparative examples 1、2、3 For all of these, the ASR (resistance value) tends to increase at lower temperatures, but in particular, compared to Examples 1 and 2, Comparative Examples 2 and 3 However, it was found that the ASR tends to be higher at lower temperatures. In other words, the CoMn added to the diffusion layer 6b mass The larger the proportion, the stronger the tendency for ASR to increase at lower temperatures. On the other hand, the amount of CoMn to the diffusion layer 6b mass The ASR values ​​for Examples 1 and 2, where the proportion is 40% by mass or less, are the same as those of the comparative example without CoMn in all temperature ranges. 1 In comparison, it showed a similar level of ASR (no decrease in electronic conductivity was observed), indicating that the CoMn metal oxide in the diffusion layer massThe proportion should preferably be 40% by mass or less.

[0084] Comparative Example 1~3 and Example 1 、2 Figures 4-8 show cross-sectional SEM images of the counter electrode layer 6, which serves as the air electrode (cathode) of the electrochemical element E in its early stages of manufacturing. The white areas represent the LSCF framework, and the gray areas represent the CoMn metal oxide. Furthermore, the comparative example 1~3 and Example 1 、2 Regarding this, the test results when temperature acceleration was performed at 900°C for 100 hours are shown in Figures 9 to 13.

[0085] Comparative Example 1 (LSCF alone: ​​Figure 9) It was confirmed that sintering (particle growth) progressed significantly due to temperature acceleration. As a result, it is presumed that the gas diffusivity of the diffusion layer 6b decreases. On the other hand, Example 1 , 2 and Comparative Examples 2, 3 (Figures 10-13) show that sintering is also progressing in CoMn metal oxides. Comparative Examples 2 and 3 This shows that the sintering of the CoMn metal oxide is performed more effectively than in Examples 1 and 2.

[0086] Furthermore, in Examples 1 and 2, CoMn metal oxides were arranged around the LSCFs, and the contact ratio between LSCFs and between CoMn metal oxides was reduced, which is presumed to have suppressed sintering. From the above results, it is clear that mixing CoMn metal oxide with LSCF is effective in improving the durability of the diffusion layer 6b by preventing sintering, and in particular, the LSCF mass The proportion is set to 80% by mass or more and 60% by mass or less, and the CoMn metal oxide mass By setting the ratio to between 20% by mass and 40% by mass, we confirmed that the required effects of electronic conductivity and diffusivity (sintering suppression) for the diffusion layer 6b were significantly achieved.

[0087] Next, Comparative Example 1 mentioned above ~3 and Example 1 、2 The transition metal contained in the diffusion layer 6b MassThe ratios are shown in [Table 1]. Furthermore, the composition of LSCF in diffusion layer 6b is La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3-δ The composition of the CoMn metal oxide is Co 1.5 Mn 1.5 O4, Co2MnO4, Co 2.5 Mn 0.5 It is one of the O4 elements, where δ is the oxygen vacancy amount. Here, the composition of the CoMn metal oxide used in the test is Co 1.5 Mn 1.5 It is O4.

[0088] [Table 1]

[0089] As shown in Table 1 above, the composition of LSCF is La 0.6 Sr 0.4 CoO is Co in the diffusion layer 6b mass La's mass The ratio of 1.051 Preferably, the value is within the range of 2.762 or less. Furthermore, the amount of Mn in the diffusion layer 6b mass La's mass The ratio 、4 .04 4 It is preferable to have one. Although not within the scope of the rights of this application, the electrochemical element has a composition of LSCF as shown in [Table 1] above. 0.6 Sr 0.4 The material is CoO, and the ratio of the weight of La to the weight of Co in the diffusion layer 6b may be in the range of 0.216 to 2.762. Furthermore, although not within the scope of the present application, the electrochemical element may also have a ratio of the weight of La to the weight of Mn in the diffusion layer 6b that is in the range of 0.250 to 4.044.

[0090] figure 14 This is a diagram showing the configuration of energy system Z and electrochemical apparatus Y. The energy system Z includes an electrochemical device Y and a heat exchanger 53 which serves as a waste heat utilization unit for reusing the heat discharged from the electrochemical device Y. The electrochemical apparatus Y comprises at least an electrochemical module M and a reformer 34, which acts as a fuel converter through which a gas containing reducing components flows to the electrochemical module M. In addition, the electrochemical apparatus Y comprises the electrochemical module M and an inverter 38, which acts as a power converter for extracting power from the electrochemical module M. Furthermore, the fuel supply module of the electrochemical apparatus Y consists of a desulfurizer 20, a vaporizer 33, and a reformer 34, etc., and supplies fuel gas containing reducing components to the electrochemical module M.

[0091] In addition, the electrochemical apparatus Y includes a reformed water tank 21, a blower 35, a combustion unit 36, a control unit 39, a storage container 40, a booster pump 41, a reformed water pump 43, and the like.

[0092] The vaporizer 33, reformer 34, electrochemical module M, and combustion section 36 are housed in a storage container 40. The reformer 34 uses the heat of combustion generated by the combustion of reaction exhaust gas in the combustion section 36 to reform the raw fuel.

[0093] The raw fuel is supplied to the desulfurizer 20 through the raw fuel supply line 42 by the operation of the booster pump 41. The reformed water from the reformed water tank 21 is supplied to the vaporizer 33 through the reformed water supply line 44 by the operation of the reformed water pump 43. The raw fuel supply line 42 then merges with the reformed water supply line 44 downstream of the desulfurizer 20, and the reformed water and raw fuel, which have merged outside the storage container 40, are supplied to the vaporizer 33 located inside the storage container 40.

[0094] The desulfurizer 20 removes (desulfurizes) sulfur compounds contained in hydrocarbon raw fuels such as city gas. When sulfur compounds are present in the raw fuel, the desulfurizer 20 can suppress the influence of sulfur compounds on the reformer 34 or on the single cell C of the electrochemical element E that constitutes the electrochemical module M. The vaporizer 33 generates steam from the reformed water supplied from the reformed water tank 21. The raw fuel containing the steam generated in the vaporizer 33 is supplied to the reformer 34 through the steam-containing raw fuel supply passage 45.

[0095] The reformer 34 uses the steam generated in the vaporizer 33 to steam reform the raw fuel that has been desulfurized in the desulfurizer 20, thereby producing a reformed gas containing hydrogen. The reformed gas produced in the reformer 34 is supplied to the gas manifold 17 of the electrochemical module M through the reformed gas supply line 46.

[0096] The electrochemical elements E constituting the electrochemical module M are arranged in parallel, electrically connected to each other, and one end (lower end) of each electrochemical element E is fixed to the gas manifold 17. The reformed gas supplied to the gas manifold 17 is distributed to the multiple electrochemical elements E. The electrochemical elements E constituting the electrochemical module M generate electricity by performing an electrochemical reaction using the reformed gas supplied from the reformer 34 and the air supplied from the blower 35. The reaction exhaust gas, which includes residual hydrogen gas not used in the reaction, is discharged from the upper end of the electrochemical module M to the combustion section 36. The combustion section 36 mixes the reaction exhaust gas discharged from the electrochemical module M with air to burn the combustible components in the reaction exhaust gas.

[0097] The reaction exhaust gas burned in the combustion section 36 becomes combustion exhaust gas and is discharged to the outside of the storage container 40 from the combustion exhaust gas outlet 50. A combustion catalyst section 51 (for example, a platinum-based catalyst) is placed at the combustion exhaust gas outlet 50 to burn and remove reducing components such as carbon monoxide and hydrogen contained in the combustion exhaust gas. The combustion exhaust gas discharged from the combustion exhaust gas outlet 50 is sent to the heat exchanger 53 via the combustion exhaust gas discharge passage 52.

[0098] The heat exchanger 53 exchanges heat between the combustion exhaust gas generated by combustion in the combustion section 36 and the supplied chilled water to produce hot water. In other words, the heat exchanger 53 operates as a waste heat utilization unit that reuses the heat discharged from the electrochemical apparatus Y.

[0099] Alternatively, instead of a waste heat utilization unit, a reaction exhaust gas utilization unit may be provided that utilizes the reaction exhaust gas discharged (without combustion) from the electrochemical module M. The reaction exhaust gas contains residual hydrogen gas that was not used in the reaction by the electrochemical elements E that make up the electrochemical module M. In the reaction exhaust gas utilization unit, the residual hydrogen gas is used for heat utilization by combustion or power generation by fuel cells, etc., thereby enabling the efficient use of energy.

[0100] The inverter 38 adjusts the output power of the electrochemical module M to the same voltage and frequency as the power received from the commercial grid (not shown). The control unit 39 controls the operation of the electrochemical apparatus Y and the energy system Z.

[0101] <Another Embodiment> <1> In the above embodiment, an example of the structure of the electrochemical element E has been described, but the structure of the electrochemical element E can be changed as appropriate. For example, a configuration in which the electrochemical element E does not have a metal support 1 may be adopted, that is, a configuration in which the single cell C is not supported by the metal support 1.

[0102] <2> In the above embodiment, an example of using the electrochemical module M in a solid oxide fuel cell was described, but the electrochemical module M can also be used in solid oxide electrolytic cells, oxygen sensors using solid oxides, and the like.

[0103] In the above embodiment, a configuration that can improve the efficiency of converting chemical energy such as fuel into electrical energy was described. In other words, in the above embodiment, a single cell C as an electrochemical element E constituting the electrochemical module M is operated as a fuel cell, hydrogen gas is circulated through the electrode layer 2, and oxygen gas is circulated through the counter electrode layer 6. As a result, oxygen molecules O2 in the counter electrode layer 6 have electrons e - It reacts with oxygen ions O 2- This is produced. The oxygen ion O 2- The hydrogen molecules H2 move through the electrolyte layer 4 to the electrode layer 2. In the electrode layer 2, the hydrogen molecules H2 move into oxygen ions O 2- It reacts with water (H2O) and electrons (e). -is generated. Through the above reactions, an electromotive force is generated between the electrode layer 2 and the counter electrode layer 6, and power generation is performed.

[0104] A case of realizing a solid oxide type electrolytic cell that includes an electrochemical module M and causes an electrolytic reaction in a single cell C of an electrochemical element E will be described. Figure 15 In the energy system Z shown in the figure, when the electrochemical element E constituting the electrochemical module M operates as an electrolytic cell, a gas containing water vapor or carbon dioxide is circulated through the electrode layer 2 as a cathode (hydrogen generation electrode), and a voltage is applied between the electrode layer 2 and the counter electrode layer 6 as an anode (oxygen generation electrode). Then, electrons e - react with water molecules H2O and carbon dioxide molecules CO2 in the electrode layer 2 to form hydrogen molecules H2 and carbon monoxide CO and oxygen ions O 2- becomes. The oxygen ions O 2- move through the electrolyte layer 4 to the counter electrode layer 6. In the counter electrode layer 6, the oxygen ions O 2- release electrons to become oxygen molecules O2. Through the above reactions, water molecules H2O are electrolyzed into hydrogen H2 and oxygen O2, and when a gas containing carbon dioxide molecules CO2 is circulated, it is electrolyzed into carbon monoxide CO and oxygen O2. That is, in the said other embodiment (2), the counter electrode layer 6 as an anode (oxygen generation electrode) has an active layer (not shown) where an oxidation-reduction reaction occurs from the side of the electrolyte layer and a diffusion layer (not shown) that diffuses gas. In addition, when it is the electrode layer 2 as an anode (oxygen generation electrode), the electrode layer 2 has an active layer (not shown) where an oxidation-reduction reaction occurs from the side of the electrolyte layer and a diffusion layer (not shown) that diffuses gas.

[0105] When a gas containing water vapor and carbon dioxide molecules (CO2) is being circulated, a fuel converter 91 can be provided to synthesize various compounds such as hydrocarbons from hydrogen and carbon monoxide produced by the electrochemical module M through electrolysis. A fuel supply unit (not shown) can circulate the hydrocarbons produced by this fuel converter 91 to the electrochemical module M, or it can be taken out of this system / device and used separately as fuel or chemical raw material. In other words, the fuel supply unit supplies reducing component gas from the fuel converter 91 to the electrochemical element E or the electrochemical module M, or supplies reducing component gas from the electrochemical element E or the electrochemical module M to the fuel converter 91.

[0106] Thus, Figure 15 In the energy system Z shown, the electrochemical device Y comprises at least an electrochemical module M and a fuel converter 91 that converts the gas containing reducing components produced by the electrochemical module M. The electrochemical device Y also comprises at least an electrochemical module M and a power converter 93 that supplies electricity to the electrochemical module M.

[0107] The electrochemical module M comprises multiple electrochemical elements E, a gas manifold 17, and a gas manifold 171. The multiple electrochemical elements E are arranged in parallel and electrically connected to each other. One end (lower end) of each electrochemical element E is fixed to the gas manifold 17, and the other end (upper end) is fixed to the gas manifold 171. The gas manifold 17 at one end (lower end) of the electrochemical element E receives a supply of water vapor and carbon dioxide. The hydrogen and carbon monoxide produced by the above-mentioned reaction in the electrochemical element E are collected by the gas manifold 171, which is in communication with the other end (upper end) of the electrochemical element E.

[0108] figure 15 The internal heat exchanger 90 is operated as a waste heat utilization unit that exchanges heat between the reaction heat generated by the reaction occurring in the fuel converter 91 and water, and vaporizes it. 15By configuring the internal heat exchanger 92 to operate as a waste heat utilization unit that preheats by exchanging heat between the waste heat generated by the electrochemical element E and water vapor and carbon dioxide, energy efficiency can be increased. Furthermore, the power converter 93 supplies power to the single cell C that constitutes the electrochemical element E. As a result, the electrochemical element E acts as an electrolytic cell, as described above.

[0109] <3> In the above embodiment, composite materials such as NiO-GDC, Ni-GDC, NiO-YSZ, Ni-YSZ, CuO-CeO2, and Cu-CeO2 were used as the material for the electrode layer 2, and composite oxides such as LSCF and LSM were used as the material for the counter electrode layer 6. The electrochemical element E configured in this way can be used as a solid oxide fuel cell by supplying hydrogen gas to the electrode layer 2 to serve as the fuel electrode (anode) and supplying air to the counter electrode layer 6 to serve as the air electrode (cathode). It is also possible to modify this configuration to construct the electrochemical element E such that electrode layer 2 is the air electrode and counter electrode layer 6 is the fuel electrode. Specifically, composite oxides such as LSCF and LSM can be used as the material for electrode layer 2, and composite materials such as NiO-GDC, Ni-GDC, NiO-YSZ, Ni-YSZ, CuO-CeO2, and Cu-CeO2 can be used as the material for counter electrode layer 6. With an electrochemical element E configured in this way, air can be supplied to electrode layer 2 to make it the air electrode, and hydrogen gas can be supplied to counter electrode layer 6 to make it the fuel electrode, allowing the electrochemical element E to be used as a solid oxide fuel cell. In this case, the electrode layer 2 has an active layer (not shown) on the side of the electrolyte layer 4 where the oxidation-reduction reaction takes place, and a diffusion layer (not shown) for diffusing gas.

[0110] <4> In the above embodiment, the electrochemical element E may be configured without either the intermediate layer 3 (insertion layer) or the reaction prevention layer 5, or without both. That is, it is also possible to have a configuration in which the electrode layer 2 and the electrolyte layer 4 are in contact, or a configuration in which the electrolyte layer 4 and the counter electrode layer 6 are in contact. In this case, the intermediate layer formation step and the reaction prevention layer formation step are omitted in the above manufacturing method. It is also possible to add steps for forming other layers or to stack multiple layers of the same type.

[0111] <5> In the above embodiment, mainly planar or cylindrical planar solid oxide fuel cells were used as the electrochemical element E, but other electrochemical elements such as cylindrical solid oxide fuel cells can also be used.

[0112] <6> In the above embodiment, the electrochemical apparatus Y includes an electrochemical module M comprising a plurality of electrochemical elements E. However, the electrochemical apparatus Y of the above embodiment can also be applied to a configuration comprising a single electrochemical element E.

[0113] <7> In the above embodiment, the electrochemical element E has a U-shaped member 9 attached to the back surface of the metal support 1, and the cylindrical support is formed by the two members, the metal support 1 and the U-shaped member 9. However, the cylindrical support may be formed by integrally forming the metal support 1 and the U-shaped member 9 using a single member, or by forming the cylindrical support using three or more members. Furthermore, the U-shaped member 9 may be omitted, and the electrode layer 2, etc., may be supported by the metal support 1.

[0114] <8> In the above embodiment, in the diffusion layer 6b of the air electrode, suitable materials include granular LSCF and particulate CoMn metal oxide. mass Although ratios have been given as examples, the bonding material 10 according to the present invention is as described above. mass It is not limited to those that have a ratio.

[0115] <9> In the above embodiment, a preferred transition metal is contained in the diffusion layer 6b of the air electrode. massAlthough ratios have been given as examples, the diffusion layer 6b according to the present invention is as described above. mass It is not limited to those that have a ratio.

[0116] <10> The configurations disclosed in the above embodiments can be applied in combination with configurations disclosed in other embodiments, provided that no inconsistencies arise. Furthermore, the embodiments disclosed herein are illustrative, and the embodiments of the present invention are not limited thereto and can be modified as appropriate without departing from the purpose of the present invention. [Industrial applicability]

[0117] The electrochemical element, electrochemical module, solid oxide fuel cell, solid oxide electrolytic cell, electrochemical device, energy system, and method for manufacturing the electrochemical element of the present invention can be effectively utilized as they can suppress the decrease in gas diffusion performance due to sintering while maintaining electronic conductivity and oxygen reduction reaction. [Explanation of Symbols]

[0118] 2: Electrode layer 4: Electrolyte layer 6: Counter electrode layer (an example of an air electrode) 6a:Active layer 6b: Diffusion layer 26: Alloy components (an example of inter-cell connecting components) E: Electrochemical element M: Electrochemical Module Y: Electrochemical apparatus Z: Energy System

Claims

1. The electrode layer, electrolyte layer, and counter electrode layer are stacked in the order described above. The electrochemical element is such that the air electrode or oxygen-generating electrode, which is either the electrode layer or the counter electrode layer, has an active layer in which an oxidation-reduction reaction takes place from the side of the electrolyte layer and a diffusion layer for diffusing gas, The aforementioned diffusion layer is composed of a mixture of particulate LSCF and CoMn metal oxide, which is a metal oxide containing particulate Co and Mn.

2. The electrochemical element according to claim 1, wherein the particle size of the particulate LSCF is larger than the particle size of the particulate CoMn metal oxide.

3. The weight percentage of the LSCF in the diffusion layer is 20% by mass or more and 80% by mass or less. The electrochemical element according to claim 1 or 2, wherein the weight percentage of the CoMn metal oxide in the diffusion layer is 80% by mass or less.

4. The weight percentage of the LSCF in the diffusion layer is 20% by mass or more and 80% by mass or less. The electrochemical element according to claim 1 or 2, wherein the weight percentage of the CoMn metal oxide in the diffusion layer is 40% by mass or less.

5. The composition of the aforementioned LSCF is La ０．６ Sr ０．４ Co ０．２ Fe ０．８ O ３－δ And, The composition of the CoMn metal oxide is Co １．５ Mn １．５ O ４ 、 Co ２ MnO ４ 、 Co ２．５ Mn ０．５ O ４ and is at least one of them The electrochemical element according to claim 1 or 2, wherein the ratio of the weight of La to the weight of Co in the diffusion layer is in the range of 0.216 to 2.

762. However, δ is the amount of oxygen vacancies.

6. The composition of the aforementioned LSCF is La ０．６ Sr ０．４ Co ０．２ Fe ０．８ O ３－δ And, The composition of the aforementioned CoMn metal oxide is Co １．５ Mn １．５ O ４ Co ２ MnO ４ Co ２．５ Mn ０．５ O ４ It is at least one of the following: The electrochemical element according to claim 1 or 2, wherein the ratio of the weight of La to the weight of Mn in the diffusion layer is in the range of 0.250 to 4.

044. However, δ is the amount of oxygen vacancies.

7. The particle size of the LSCF is 0.20 μm or more and 0.50 μm or less. The electrochemical element according to claim 1 or 2, wherein the particle size of the CoMn metal oxide is 0.10 μm or more and 0.19 μm or less.

8. The electrode layer, electrolyte layer, and counter electrode layer are stacked in the order described above. A method for manufacturing an electrochemical element in which the air electrode or oxygen generating electrode, which is either the electrode layer or the counter electrode layer, has an active layer in which an oxidation-reduction reaction is carried out from the side of the electrolyte layer and a diffusion layer for diffusing gas, A manufacturing method comprising a diffusion layer sintering step, in which a mixture of particulate LSCF and CoMn metal oxide, which is a metal oxide containing particulate Co and Mn, is applied to the active layer as the diffusion layer and sintered.

9. The manufacturing method according to claim 8, comprising a pre-sintering step of sintering the particulate LSCF before the diffusion layer sintering step.

10. The particle size of the LSCF after the pre-sintering step and before the diffusion layer sintering step is larger than the particle size of the CoMn metal oxide before the diffusion layer sintering step. The particle size of the particulate LSCF after the pre-sintering step and before the diffusion layer sintering step is 0.20 μm or more and 0.50 μm or less. The manufacturing method according to claim 9, wherein the particle size of the particulate CoMn metal oxide before the diffusion layer sintering step is 0.10 μm or more and 0.19 μm or less.

11. An electrochemical module comprising a plurality of electrochemical elements as described in claim 1 or 2, connected and arranged in an assembled state.

12. A solid oxide fuel cell that generates an electricity reaction using the electrochemical element described in claim 1 or 2.

13. A solid oxide type electrolytic cell that generates an electrolytic reaction using the electrochemical element described in claim 1 or 2.

14. The electrochemical module and fuel converter described in claim 11 are provided. An electrochemical apparatus having a fuel supply unit that supplies a reducing component gas from the fuel converter to the electrochemical element or the electrochemical module, or supplies a reducing component gas from the electrochemical element or the electrochemical module to the fuel converter.

15. The electrochemical module according to claim 11, An electrochemical apparatus comprising at least a power converter that extracts power from the electrochemical element or the electrochemical module, or that supplies power to the electrochemical element or the electrochemical module.

16. The electrochemical apparatus according to claim 14, An energy system comprising at least a waste heat utilization unit for reusing heat discharged from the electrochemical apparatus.

17. The electrochemical apparatus according to claim 15, An energy system comprising at least a waste heat utilization unit for reusing heat discharged from the electrochemical apparatus.

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