Electrode layer formation method

Abstract

To provide an electrode layer formation method having no need to supply hydrogen during firing and also capable of suppressing equipment costs required for manufacturing.SOLUTION: A method for forming an electrode layer 2 on a metal support 1 includes: an electrode layer lamination step of laminating the electrode layer 2 on the metal support 1; and a firing step of firing the electrode layer 2 laminated on the metal support 1, the firing step being performed in an atmosphere where the partial pressure of oxygen is 4.0×10-8 bar or more and 4.0×10-6 bar or less.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This invention relates to an electrode layer formation method. In the law To relate to. [Background technology]

[0002] In conventional electrolyte-supported solid oxide fuel cells (SOFCs) and electrode-supported SOFCs, firing at high temperatures (e.g., around 1400°C) is performed to obtain sufficient adhesion strength between layers and high-quality electrode and electrolyte layers.

[0003] In recent years, metal-supported SOFCs have been developed to improve robustness, in which the fuel electrode, air electrode, and electrolyte layer are supported on a metal substrate.

[0004] When manufacturing metal-supported SOFCs, high-temperature heat treatment (e.g., around 1400°C) can lead to the formation of a thick metal oxide film containing Cr on the surface of the metal support, making it prone to cracking and delamination. Furthermore, the diffusion of Cr and other elements from the metal support can affect the SOFC's components (electrode layer, electrolyte layer), potentially reducing the SOFC's performance and durability.

[0005] Therefore, as a conventional method for manufacturing metal-supported SOFCs, for example, the method described in Patent Document 1 has been proposed.

[0006] The method described in Patent Document 1 is a method for forming a fuel electrode layer by performing steps such as pre-firing an unfired fuel electrode layer at a temperature of 950 to 1100°C under non-reducing conditions for 15 to 60 minutes, or firing it at a temperature of 950 to 1100°C for 15 to 60 minutes in a reducing atmosphere using a gaseous reducing agent such as hydrogen. [Prior art documents] [Non-patent literature]

[0007] [Patent Document 1] Patent No. 6794505 [Overview of the project]

Problems to be Solved by the Invention

[0008] However, in the method described in Patent Document 1, it is necessary to perform firing at a high temperature of 950 to 1100°C while supplying a gas containing hydrogen. Therefore, in order to appropriately process the gas, equipment with explosion-proof specifications is required, resulting in a problem of high equipment costs.

[0009] The present invention has been made in view of the above circumstances, and an object thereof is to provide a method for forming an electrode layer that does not require the supply of hydrogen during firing and can suppress the equipment costs required for production. Law

Means for Solving the Problems

[0010] The characteristic configuration of the electrode layer forming method according to the present invention for achieving the above object is a method for forming an electrode layer on a metal support, The electrode layer is made of at least one selected from nickel-based compounds, ceria-based compounds, zirconia-based oxides, and perovskite-based composite oxides, or a combination thereof. an electrode layer stacking step of stacking an electrode layer on the metal support, and a firing step of firing the electrode layer stacked on the metal support, and the firing step is Under an inert gas atmosphere with a dew point between 10°C and 70°C, performed in an atmosphere where the partial pressure of oxygen is 4.0×10 -8 bar or more and 4.0×10 -6 bar or less. 、 At temperatures between 800°C and 1100°C

[0011] As a result of intensive research, the inventor of the present application has found that when forming an electrode layer on a metal support, firing in an atmosphere where the partial pressure of oxygen is 4.0×10 -8 bar or more and 4.0×10 -6 bar or less without supplying hydrogen can achieve high adhesion strength with the metal support and form a high-quality electrode layer, leading to the completion of the present invention. , in an inert gas atmosphere with a dew point of 10°C to 70°C, at a temperature of 800°C to 1100°C.

[0012] If the firing temperature is too low, there is a risk that a good electrode layer will not be formed, while if the firing temperature is too high, the metal support may be damaged. However, ​​​According to the above characteristic configuration, the adhesion strength with the metal support is high, and a high-quality electrode layer can be formed on the metal support. Furthermore, damage to the metal support can also be suppressed. Furthermore, hydrogen supply is not required during firing. Oxygen partial pressure 4.0 × 10⁻⁶ using only humidified inert gas -8 bar or more 4.0 x 10 -6 To create an atmosphere below that of a bar, This reduces the equipment costs required for manufacturing.

[0015] Further characteristic features of the electrode layer formation method of the present invention are: The key point is that the inert gas is nitrogen.

[0016] Nitrogen is relatively inexpensive and does not require special equipment for handling. Therefore, the above-described configuration can reduce the cost of forming the electrode layer.

[0019] Further characteristic features of the electrode layer formation method of the present invention are: The key feature is that a degreasing step is performed to remove oil before carrying out the aforementioned firing step.

[0020] According to the above-described configuration, defects in electrode layer film formation caused by oil and grease can be suppressed, and good quality of electrochemical elements and other components can be ensured.

[0021] Further characteristic features of the electrode layer formation method of the present invention are: The degreasing step is performed at a temperature between 150°C and 650°C.

[0022] If the degreasing temperature is too low, there is a risk that oil and other contaminants will not be removed sufficiently. On the other hand, if the degreasing temperature is too high, there is a possibility that the metal support will be damaged or that a good quality electrode layer will not be formed. However, with the above-described configuration, oil and other contaminants can be properly removed while suppressing damage to the metal support and forming a good quality electrode layer. [Brief explanation of the drawing]

[0049] [Figure 1] This figure shows a schematic configuration of a metal-supported electrochemical element according to one embodiment. [Figure 2] This figure shows a schematic configuration of an electrochemical module according to one embodiment. [Figure 3] This figure shows a schematic configuration of an electrochemical apparatus and energy system according to one embodiment. [Figure 4] This image was obtained by photographing the metal support of Example 4 after the peel test. [Figure 5] This image was obtained by photographing the metal support of Example 6 after the peel test. [Figure 6] This image was obtained by photographing the metal support of Comparative Example 2 after the peel test. [Figure 7] This figure shows a schematic configuration of an electrochemical apparatus and energy system according to a different embodiment. [Figure 8] This figure shows a schematic configuration of an electrochemical module according to another embodiment. [Modes for carrying out the invention]

[0050] The following describes the electrode layer 2 according to the embodiment, the method for forming the electrode layer 2, the metal-supported electrochemical element E equipped with the electrode layer 2, the method for manufacturing the metal-supported electrochemical element E, the solid oxide fuel cell (SOFC), the electrochemical module M, the electrochemical device Y, and the energy system Z. In this embodiment, the metal-supported electrochemical element E is used as a component of a solid oxide fuel cell that generates electricity by receiving a fuel gas containing hydrogen and air (oxidizer gas). In the following, when describing the positional relationship of the layers, for example, the side of the counter electrode layer 6 as viewed from the electrolyte layer 4 may be referred to as "up" or "upper side," and the side of the electrode layer 2 may be referred to as "down" or "lower side." Also, the side of the metal support 1 on which the electrode layer 2 is formed may be referred to as the "front side," and the opposite side may be referred to as the "back side."

[0051] (Electrochemical element) As shown in Figure 1, the metal-supported electrochemical element E is a metal-supported electrochemical element having a metal support 1, an electrode layer 2, 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. The electrode layer 2 is porous, and the electrolyte layer 4 is dense.

[0052] (metal support) The metal support 1 maintains the strength of the metal-supported electrochemical element E by supporting the electrode layer 2, the intermediate layer 3, the electrolyte layer 4, the reaction prevention layer 5, and the counter electrode layer 6. In other words, the metal support 1 plays the role of a support for the components of the electrochemical element.

[0053] As the material for the metal support 1, a material with excellent electronic conductivity, heat resistance, oxidation resistance, and corrosion resistance is used. For example, ferritic stainless steel, austenitic stainless steel, nickel-based alloys, etc., can be used. In particular, alloys containing chromium are preferably used. In this embodiment, the metal support 1 uses an Fe-Cr alloy containing 18% to 25% by mass of Cr, but it is especially preferable to use an Fe-Cr alloy containing 0.05% or more by mass of Mn, an Fe-Cr alloy containing 0.15% to 1.0% by mass of Ti, an Fe-Cr alloy containing 0.15% to 1.0% by mass of Zr, an Fe-Cr alloy containing Ti and Zr with a total Ti and Zr content of 0.15% to 1.0% by mass, or an Fe-Cr alloy containing 0.10% to 1.0% by mass of Cu. Furthermore, it is preferable that the metal support 1 be made of ferritic stainless steel, as this allows for the realization of an inexpensive and high-strength metal-supported electrochemical element.

[0054] The metal support 1 is plate-shaped overall. The metal support 1 only needs to have sufficient strength to form a metal-supported electrochemical element E as a support. From the viewpoint of ensuring strength, its thickness is preferably 0.1 mm or more, more preferably 0.15 mm or more, and even more preferably 0.2 mm or more. From the viewpoint of suppressing costs, its thickness is preferably 2 mm or less, more preferably 1 mm or less, and even more preferably 0.5 mm or less. The metal support 1 has a plurality of through holes 1a that penetrate from the surface on which the electrode layer 2 is provided (the front surface) to the back surface. In this embodiment, the metal support 1 is a metal plate with a plurality of through holes 1a provided by mechanical, chemical, or optical perforation (hole processing) such as punching, etching, or laser processing, so as to penetrate the front surface and the back surface of the metal plate. This allows for a smooth supply of fuel gas and air from the back surface of the metal support 1 to the electrode layer 2 side, thereby realizing a high-performance metal-supported electrochemical element. Furthermore, the plate-shaped metal support 1 can be bent or otherwise deformed into shapes such as a box or cylinder for use.

[0055] A metal oxide layer 1b is provided on the surface of the metal support 1 as a diffusion-preventing layer. That is, a diffusion-preventing layer is formed between the metal support 1 and the electrode layer 2, which will be described later. The metal oxide layer 1b is provided not only on the surface of the metal support 1 that is exposed to the outside, but also on the contact surface (interface) with the electrode layer 2 and on the inner surface of the through hole 1a. This metal oxide layer 1b can suppress elemental interdiffusion between the metal support 1 and the electrode layer 2. For example, if ferritic stainless steel containing chromium is used as the metal support 1, the metal oxide layer 1b will mainly consist of chromium oxide. The metal oxide layer 1b, which is mainly composed of chromium oxide, suppresses the diffusion of chromium atoms etc. from the metal support 1 to the electrode layer 2 and electrolyte layer 4. The thickness of the metal oxide layer 1b should be such that high diffusion-preventing performance and low electrical resistance are both achieved, and it is preferable that the maximum thickness is 3 μm or less. It is more preferable that it be on the submicron order, and specifically, it is more preferable that the average thickness is 0.3 μm or more and 0.7 μm or less. Furthermore, it is more preferable that the minimum thickness be approximately 0.1 μm or more. Also, it is preferable that the maximum thickness be approximately 1.1 μm or less.

[0056] The metal oxide layer 1b can be formed by various methods, but a method of oxidizing the surface of the metal support 1 to form a metal oxide is preferably used. Alternatively, the metal oxide layer 1b may be formed on the surface of the metal support 1 by sputtering, PVD methods such as PLD, CVD, spray coating methods (such as thermal spraying, aerosol deposition, aerosol gas deposition, powder jet deposition, particle jet deposition, and cold spray), or by plating and oxidation treatment. Furthermore, the metal oxide layer 1b may contain a highly conductive spinel phase or the like.

[0057] (electrode layer) As shown in Figure 1, the electrode layer 2 can be provided as a thin layer on the surface of the metal support 1 so as to cover the region in which the through-holes 1a of the metal support 1 are formed. 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 material used and reduce costs while ensuring sufficient electrode performance. Furthermore, the region in the metal support 1 in which the through-holes 1a are provided is entirely covered by the electrode layer 2. In other words, the through-holes 1a are formed inside the region in the metal support 1 in which the electrode layer 2 is formed. In other words, all the through-holes 1a are provided facing the electrode layer 2.

[0058] The electrode layer 2 can be made from at least one of the following materials, or a combination thereof: nickel-based compounds, ceria-based oxides, zirconia-based oxides, and perovskite-based composite oxides. For example, 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 constructed using these materials functions as an anode. By using these materials, a nanocomposite structure is formed, and the electrode layer 2 acquires sufficient electrode performance.

[0059] Furthermore, the electrode layer 2 is preferably formed by a low-temperature firing method (e.g., a wet method using a firing process in a low-temperature range that does not involve firing at a high temperature above 1100°C), a spray coating method (methods such as a spraying method, an aerosol deposition method, an aerosol gas deposition method, a powder jet deposition method, a particle jet deposition method, a cold spray method, etc.), a PVD method (such as a sputtering method or a pulsed laser deposition method), a CVD method, or the like. By using these processes that can be used in a low-temperature range, for example, a good electrode layer 2 can be obtained without using firing in a high-temperature range above 1100°C. Therefore, it is preferable because it is possible to prevent damage to the metal support 1 and suppress the elemental diffusion between the metal support 1 and the electrode layer 2, thereby realizing a metal-supported electrochemical element with excellent durability. Furthermore, it is more preferable to use the low-temperature firing method because it facilitates the handling of raw materials.

[0060] In the present embodiment, the electrode layer 2 is formed through a firing step performed in an atmosphere where the partial pressure of oxygen is 4.0×10 -8 bar or more and 4.0×10 -6 bar or less, and thus has a tensile strength of 1.2 MN / m 2 or more, excellent adhesion to the metal support 1, and also good adhesion to the intermediate layer 3. Therefore, the metal-supported electrochemical element has excellent strength (reliability), durability, and performance.

[0061] In order to impart gas permeability to the electrode layer 2, the electrode layer 2 has a plurality of pores inside and on its surface. That is, the electrode layer 2 is formed as a porous layer. From the perspective of forming a three-dimensional gas diffusion path, the porosity of the electrode layer 2 is preferably 5% or more, and more preferably 5% or more and 60% or less. Also, the electrode layer 2 is formed such that its density, for example, is greater than 40% and less than 95%. The size of the pores can be appropriately selected to be a size suitable for a smooth reaction to proceed during the electrochemical reaction. Note that the density is the ratio occupied in the space of the material constituting the layer and can be expressed as (1 - porosity), and is equivalent to the relative density.

[0062] (Middle class) As shown in Figure 1, the intermediate layer 3 can be formed as a thin layer on top of the electrode layer 2, covering the electrode layer 2. In this way, the intermediate layer 3 is positioned between the porous electrode layer 2 and the dense electrolyte layer 4, continuously connecting the two layers and acting as a buffer layer that relieves various stresses that occur during the manufacturing and operation of the metal-supported electrochemical element E. For this reason, the intermediate layer 3 is intentionally formed to have a density lower than that of the electrolyte layer 4. Alternatively, the intermediate layer 3 may be intentionally formed to have a density higher than that of the electrode layer 2. As a result, even when a porous electrode layer 2 and a dense electrolyte layer 4 are formed on the metal support 1, the intermediate layer 3 absorbs and relieves various stresses between each layer, thereby improving the performance, reliability, and stability of the metal-supported electrochemical element E. 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. By using this thickness, it becomes possible to reduce the amount of expensive intermediate layer material used, thereby lowering costs while ensuring sufficient performance.

[0063] 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., can be used. Ceria-based ceramics are particularly preferred.

[0064] 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, or cold spray), PVD (such as sputtering or pulsed laser deposition), or CVD. These film formation processes, which can be used in low temperature ranges, allow the intermediate layer 3 to be obtained without using firing in a high temperature range higher than 1100°C, for example. Therefore, elemental interdiffusion between the metal support 1 and the electrode layer 2 can be suppressed without damaging the metal support 1, and a highly durable metal-supported electrochemical element E can be realized. Furthermore, using a low-temperature firing method is even more preferable because it simplifies the handling of raw materials.

[0065] In this embodiment, the intermediate layer 3 is preferably an oxygen ion (oxide ion) conductor or a mixed conductor having conductivity for both oxygen ions (oxide ions) and electrons. An intermediate layer 3 having such properties is suitable for application to a metal-supported electrochemical element E.

[0066] (electrolyte layer) As shown in Figure 1, the electrolyte layer 4 is formed as a thin layer on the intermediate layer 3. It can also be formed as a thin film with a thickness of 10 μm or less. In this embodiment, the electrolyte layer 4 is provided across (straddles) both the intermediate layer 3 and the metal support 1. By configuring it in this way and bonding the electrolyte layer 4 to the metal support 1, the metal-supported electrochemical element E as a whole can be made highly robust.

[0067] Furthermore, the electrolyte layer 4 is provided on the front surface of the metal support 1 in an area larger than the area where the through-hole 1a is provided. In other words, the through-hole 1a is formed inside the area of ​​the metal support 1 where the electrolyte layer 4 is formed. This makes it possible to suppress gas leakage from the electrode layer 2 and the intermediate layer 3 around the electrolyte layer 4. To explain, when a metal-supported electrochemical element E is used as a component of an SOFC, when the SOFC is in operation, gas is supplied from the back side of the metal support 1 to the electrode layer 2 through the through-hole 1a. In the area where the electrolyte layer 4 is in contact with the metal support 1, gas leakage can be suppressed without providing a separate component such as a gasket. In this embodiment, the electrolyte layer 4 completely covers the periphery of the electrode layer 2, but it is also possible to provide the electrolyte layer 4 on top of the electrode layer 2 and the intermediate layer 3, and provide a gasket or the like around it.

[0068] As the material for the electrolyte layer 4, electrolyte materials that conduct oxygen ions such as YSZ (yttria-stabilized zirconia), SSZ (scandium-stabilized zirconia), GDC (gadolinium-doped ceria), YDC (yttrium-doped ceria), SDC (samarium-doped ceria), and LSGM (strontium-magnesium-doped lanthanum gallate), or electrolyte materials that conduct hydrogen ions such as perovskite-type oxides can be used. In particular, zirconia-based ceramics are preferably used. If the electrolyte layer 4 is made of zirconia-based ceramics, the operating temperature of the SOFC using the metal-supported electrochemical element E can be made higher compared to ceria-based ceramics and various hydrogen ion-conducting materials. For example, in this embodiment, when a metal-supported electrochemical element E is used in an SOFC, if a material capable of exhibiting high electrolyte performance even in high-temperature ranges of approximately 650°C or higher, such as YSZ, is used as the material for the electrolyte layer 4, and hydrocarbon-based fuels such as city gas or LPG are used as the raw fuel for the system, and the raw fuel is converted into the anode gas of the SOFC by steam reforming or the like, a highly efficient SOFC system can be constructed that uses the heat generated in the SOFC cell stack to reform the raw fuel gas. In this embodiment, the electrolyte layer 4 contains stabilized zirconia.

[0069] 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, or cold spray), PVD (such as sputtering or 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. This suppresses damage to the metal support 1 and inhibits elemental diffusion between the metal support 1 and the electrode layer 2, enabling the realization of a metal-supported electrochemical element E with excellent performance and durability. In particular, using low-temperature firing or spray coating is preferable because it allows for the realization of a low-cost element. 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.

[0070] 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 makes it easier to form a dense electrolyte layer with high airtightness and gas barrier properties, even when the electrolyte layer is composed of multiple layers.

[0071] (Reaction prevention layer) 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.

[0072] The reaction prevention layer 5 can be made of any material that can prevent 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, and the long-term stability of the performance of the metal-supported electrochemical element E can be improved.

[0073] The reaction prevention layer 5 preferably has oxygen ion (oxide ion) conductivity. It is even more preferable that it is a mixed conductor having conductivity for both oxygen ions (oxide ions) and electrons. A reaction prevention layer 5 having such properties is suitable for application to a metal-supported electrochemical element E.

[0074] Forming the reaction prevention layer 5 is preferably done 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 a metal-supported 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 PVD method (such as sputtering or pulsed laser deposition), or a CVD method. 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. Furthermore, using a low-temperature firing method is even preferable because it facilitates the handling of raw materials.

[0075] (Counter electrode layer) The counter electrode layer 6 can be formed as a thin layer on top of the reaction prevention layer 5. When forming 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.

[0076] As the material for the counter electrode layer 6, for example, composite oxides such as LSCF and LSM, ceria oxides, and mixtures thereof can be used. In particular, it is preferable that 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.

[0077] 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 a metal-supported 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.

[0078] (Method for manufacturing metal-supported electrochemical elements) Next, a method for manufacturing the metal-supported electrochemical element E will be described. The method for manufacturing the metal-supported electrochemical element E according to this embodiment includes an electrode layer formation step, an intermediate layer formation step, an electrolyte layer formation step, a reaction prevention layer formation step, and a counter electrode layer formation step, wherein the electrode layer formation step includes an electrode layer lamination step, a degreasing step, and a firing step. In this embodiment, the electrode layer formation step corresponds to the electrode layer formation method.

[0079] (Electrode layer formation step) In the electrode layer formation step, the electrode layer 2 is formed as a thin film on the metal support 1. The electrode layer 2 can be formed using the film deposition method described above, but in order to suppress the deterioration of the metal support 1, it is preferable to use a film deposition method that can be used in a low temperature range of 1100°C or less.

[0080] When the electrode layer formation step is performed by a low-temperature firing method, it is carried out as follows: First, the material powder of electrode layer 2 and the solvent (dispersion medium) are mixed to create a material paste, which is then applied to the front surface of the metal support 1 (electrode layer lamination step). Next, electrode layer 2 is compression molded (electrode layer smoothing step) and heated at a predetermined temperature (degreasing step). After that, it is fired at a temperature of 1100°C or lower (firing step). Compression molding of electrode layer 2 can be performed by, for example, CIP (Cold Isostatic Pressing), roll pressing, or RIP (Rubber Isostatic Pressing). The order of the electrode layer smoothing step and the electrode layer firing step can also be reversed. The electrode layer smoothing step can also be performed by lapping, leveling, or surface cutting and polishing. Furthermore, the degreasing step is preferably a heating process at a temperature of 150°C to 650°C. By performing a degreasing step, defects in the electrode layer 2 caused by oil and grease can be suppressed.

[0081] Furthermore, in this embodiment, a metal oxide layer 1b (diffusion prevention layer) is formed on the surface of the metal support 1 when the firing step in the electrode layer formation step is performed. Alternatively, a separate step of forming the diffusion prevention layer may be performed before the firing step in the electrode layer formation step.

[0082] In this embodiment, the firing step is performed when the partial pressure of oxygen is 4.0 × 10 -8 bar or more 4.0 x 10 -6 The firing step is carried out in an atmosphere adjusted so that the partial pressure of oxygen is below bar. -8 bar or more 4.0 x 10 -6 By performing the procedure in an atmosphere below bar, the electrode layer 2 reaches 1.2 MN / m 2 The tensile strength will be as described above. Therefore, the electrode layer 2 will be less likely to peel off from the metal support 1, and the adhesion strength with the intermediate layer 3 formed in the intermediate layer formation step described later will also be increased, thus enabling the realization of a highly durable metal-supported electrochemical element E. The partial pressure of oxygen is 7.5 × 10⁻⁶-8 bar or more 3.0 x 10 -6 It is preferable to be less than or equal to bar, which is 2.9 × 10 -7 bar or more 1.5 x 10 -6 It is more preferable that the partial pressure of oxygen be below bar. If the oxygen partial pressure is too low or too high, the tensile strength of the electrode layer 2 decreases, making it easier for the electrode layer 2 to peel off from the metal support 1.

[0083] Specifically, the firing step is carried out in an inert gas atmosphere with a dew point of 10°C to 70°C without supplying hydrogen. By maintaining a dew point of 10°C to 70°C, the firing temperature is maintained such that the metal support 1 does not deteriorate, and the partial pressure of oxygen is 4.0 × 10⁻⁶. -8 bar or more 4.0 x 10 -6 This can be carried out in an atmosphere below bar. The dew point is preferably 10°C to 70°C, and more preferably 20°C to 60°C, as described above. Nitrogen can be used as the inert gas.

[0084] Furthermore, the firing step is carried out at a temperature of 800°C to 1100°C in order to suppress deterioration of the metal support 1. In particular, it is preferable to carry it out at a temperature of 1050°C or lower, and more preferably at a temperature of 1000°C or lower.

[0085] (Intermediate layer formation step) In the intermediate layer formation step, an intermediate layer 3 is formed on the electrode layer 2 in a thin layer form, covering the electrode layer 2. The intermediate layer 3 can be formed using the film deposition method described above, but in order to suppress the deterioration of the metal support 1, it is preferable to use a film deposition method that can be used in a low temperature range of 1100°C or less.

[0086] When the intermediate layer formation step is performed by a low-temperature firing method, it is specifically carried out as follows: First, the material powder of the intermediate layer 3 and a solvent (dispersion medium) are mixed to prepare a material paste, which is then applied to the front surface of the electrode layer 2. Then, the intermediate layer 3 is compression molded (intermediate layer smoothing step) and fired at 1100°C or below (intermediate layer firing step). The compression molding of the intermediate layer 3 can be performed by, for example, CIP molding, roll pressure molding, or RIP molding. 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 the metal-supported electrochemical element E can be formed while suppressing damage and deterioration of the metal support 1. Furthermore, the order of the intermediate layer smoothing process and the intermediate layer firing process can be reversed. Additionally, the intermediate layer smoothing process can be performed by methods such as lapping, leveling, or surface cutting and polishing.

[0087] (Electrolyte layer formation step) 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. The electrolyte layer 4 can be formed using the film formation method usable in the low temperature range described above, but it is preferable to use the spray coating method. In particular, in order to form a high-quality electrolyte layer 4 that is dense, airtight and has high gas barrier performance in a temperature range of 1100°C or lower, it is more preferable to use one of the aerosol deposition method, aerosol gas deposition method, powder jet deposition method, or particle jet deposition method. In this embodiment, the electrolyte layer 4 is formed using the aerosol deposition method. Specifically, the aerosolized electrolyte layer 4 material powder (in this embodiment, fine powder of stabilized zirconia such as YSZ or SSZ) is sprayed toward the intermediate layer 3 on the metal support 1 to form the electrolyte layer 4.

[0088] (Reaction prevention layer formation step) In the reaction prevention layer formation step, a thin reaction prevention layer 5 is formed on the electrolyte layer 4. The reaction prevention layer 5 can be formed using the film formation method described above, but in order to suppress the deterioration of the metal support 1, it is preferable to use a film formation method that can be used in a low temperature range of 1100°C or less.

[0089] (Counter electrode layer formation step) In the counter electrode layer formation step, the counter electrode layer 6 is formed as a thin layer on the reaction prevention layer 5. The counter electrode layer 6 can be formed using the film deposition method described above, but in order to suppress the deterioration of the metal support 1, it is preferable to use a film deposition method that can be used in a low temperature range of 1100°C or less.

[0090] As described above, the electrode layer 2 has a density of 1.2 MN / m 2 By achieving the above tensile strength, the adhesion between the electrode layer 2 and the metal support 1 or intermediate layer 3 is improved, enabling the manufacture of a metal-supported electrochemical element E with superior strength (reliability), durability, and performance. Furthermore, since hydrogen supply is not required when firing the electrode layer 2 of this metal-supported electrochemical element E, the equipment costs required for manufacturing can be reduced.

[0091] (Solid oxide fuel cell) By configuring the metal-supported electrochemical element E as described above, the metal-supported electrochemical element E can be used as a power generation cell in a solid oxide fuel cell. In other words, a solid oxide fuel cell that generates electricity using the metal-supported electrochemical element E can be realized.

[0092] For example, a fuel gas containing hydrogen as the first gas is flowed from the back surface of the metal support 1 through a through hole 1a to the electrode layer 2, and air as the second gas is flowed to the counter electrode layer 6, maintaining a predetermined operating temperature (for example, 500°C to 900°C). In this case, if an electrolyte material that conducts oxygen ions is used in the electrolyte layer 4, the 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 circulating 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). - This is generated.

[0093] 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 becomes electron 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).

[0094] As a result of the above reaction, an electromotive force is generated as an electrochemical output between electrode layer 2 and counter electrode layer 6. In this case, electrode layer 2 functions as the fuel electrode (anode) of the fuel cell, and counter electrode layer 6 functions as the air electrode (cathode).

[0095] Furthermore, a solid oxide fuel cell capable of operating at temperatures of 650°C or higher during rated operation is more preferable because, in a fuel system using hydrocarbon gases such as city gas as the raw fuel, it is possible to construct a system in which the heat required to convert the raw fuel to hydrogen can be supplied by the waste heat of the fuel cell, thereby increasing the power generation efficiency of the fuel cell system. In addition, a solid oxide fuel cell operating at temperatures of 900°C or lower during rated operation is more preferable because it enhances the suppression effect of Cr volatilization from the metal-supported electrochemical element E, and a solid oxide fuel cell operating at temperatures of 850°C or lower during rated operation is even more preferable because it further enhances the suppression effect of Cr volatilization.

[0096] (Electrochemical Module) Next, the electrochemical module M will be described with reference to Figure 2. The electrochemical module M includes a metal-supported electrochemical element E in which a cylindrical support is formed by a metal support 1 and a U-shaped member 9 attached to the back surface of the metal support 1. Multiple such metal-supported electrochemical elements E are stacked (assembled) with a current collector 26 in between to form the electrochemical module M. In this embodiment, the current collector 26 is joined to the counter electrode layer 6 of the metal-supported electrochemical element E and the U-shaped member 9, electrically connecting the two. However, the counter electrode layer 6 of the metal-supported electrochemical element E and the U-shaped member 9 may be directly electrically connected.

[0097] Furthermore, the electrochemical module M includes a gas manifold 17, a termination member, and a current extraction section. Multiple stacked metal-supported electrochemical elements E have one open end of a cylindrical support connected to the gas manifold 17, and receive a supply of gas from the gas manifold 17. The supplied gas flows through the inside of the cylindrical support and is supplied to the electrode layer 2 through the through-hole 1a of the metal support 1.

[0098] (Electrochemical apparatus and energy systems) Next, with reference to Figure 3, the electrochemical apparatus Y and energy system Z constructed using the electrochemical module M described above will be explained.

[0099] As shown in Figure 3, the energy system Z includes an electrochemical apparatus Y and a heat exchanger 53 which serves as a waste heat utilization unit that reuses the heat circulating from the electrochemical apparatus Y.

[0100] In this embodiment, the electrochemical apparatus Y includes an electrochemical module M, a fuel converter consisting of a desulfurizer 31 and a reformer 34, a fuel supply unit 46 that supplies fuel gas containing the reduced components generated by the fuel converter to the electrochemical module M, and an inverter 38 which is a type of power converter that serves as an output unit for extracting power from the electrochemical module M.

[0101] More specifically, the electrochemical apparatus Y includes a desulfurizer 31, a reformed water tank 32, a vaporizer 33, a reformer 34, a blower 35, a combustion unit 36, an inverter 38, a control unit 39, an electrochemical module M, a storage container 40, and the like.

[0102] The desulfurizer 31 removes (desulfurizes) sulfur compounds contained in hydrocarbon raw fuels such as city gas. When sulfur compounds are present in the raw fuel, the desulfurizer 31 can suppress the effect of sulfur compounds on the reformer 34 or the metal-supported electrochemical element E. The vaporizer 33 generates steam from reformed water supplied from the reformed water tank 32. The reformer 34 uses the steam generated in the vaporizer 33 to steam reform the raw fuel that has been desulfurized in the desulfurizer 31, generating a reformed gas containing hydrogen.

[0103] The electrochemical module M generates electricity by using reformed gas supplied from the reformer 34 and air supplied from the blower 35 to perform an electrochemical reaction. The combustion unit 36 ​​mixes the reaction exhaust gas discharged from the electrochemical module M with air and burns the combustible components in the reaction exhaust gas.

[0104] The electrochemical module M comprises a plurality of metal-supported electrochemical elements E and a gas manifold 17. The plurality of metal-supported electrochemical elements E are arranged in parallel and electrically connected to each other, with one end (lower end) of each metal-supported electrochemical element E fixed to the gas manifold 17. The metal-supported electrochemical elements E generate electricity by causing an electrochemical reaction between the reformed gas supplied through the gas manifold 17 and the air supplied from the blower 35.

[0105] 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.

[0106] 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.

[0107] The raw fuel is supplied to the desulfurizer 31 through the raw fuel supply line 42 by the operation of the booster pump 41. The reformed water from the reformed water tank 32 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 31, 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.

[0108] The reformed water is vaporized in the vaporizer 33 to become steam. The raw fuel containing the steam generated in the vaporizer 33 is supplied to the reformer 34 through the steam-containing raw fuel supply line 45. In the reformer 34, the raw fuel is steam reformed to produce reformed gas (first gas with reducing properties) mainly composed of hydrogen gas. The reformed gas produced in the reformer 34 is supplied to the gas manifold 17 of the electrochemical module M through the fuel supply unit 46.

[0109] The reformed gas supplied to the gas manifold 17 is distributed to multiple metal-supported electrochemical elements E and supplied to the metal-supported electrochemical elements E from the lower end, which is the connection point between the metal-supported electrochemical elements E and the gas manifold 17. The hydrogen (reducing component) in the reformed gas is mainly used for the electrochemical reaction in the metal-supported electrochemical elements E. The reaction exhaust gas, which includes the remaining hydrogen gas not used in the reaction, is discharged from the upper end of the metal-supported electrochemical elements E to the combustion section 36.

[0110] The reaction exhaust gas is burned in the combustion section 36 and discharged as combustion exhaust gas 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.

[0111] 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.

[0112] 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 in the metal-supported electrochemical element E. In the reaction exhaust gas utilization unit, the residual hydrogen gas is used for heat utilization through combustion or power generation using fuel cells, etc., thereby enabling the efficient use of energy.

[0113] [Examples and Comparative Examples] Examples and comparative examples are described below.

[0114] [Formation of electrode layer] As Example 1, a metal support 1 was fabricated by laser processing a circular metal plate with a thickness of 0.3 mm and a diameter of 25 mm to create multiple through holes 1a in a region with a radius of 2.5 mm from the center.

[0115] Next, 60% by mass of NiO powder and 40% by mass of GDC powder were mixed, and an organic binder and an organic solvent (dispersion medium) were added to prepare a paste. Using this paste, an electrode layer 2 was laminated in a region with a radius of 5 mm from the center of the metal support 1 (electrode layer lamination step). Screen printing was used to form the electrode layer 2.

[0116] Subsequently, the metal support 1 on which the electrode layer 2 was laminated was degreased in air at 450°C (degreasing step).

[0117] Subsequently, the degreasing treatment of the metal support 1 was performed at a firing temperature of 850°C, with an oxygen partial pressure of 7.27 × 10⁻⁶. -8 The product was fired for 1 hour in a humidified nitrogen gas atmosphere with a dew point temperature of 20°C, adjusted to form a bar (firing step).

[0118] In Examples 2 to 7 and Comparative Examples 1 and 2, the electrode layer 2 was formed on the metal support 1 using the same procedure, except that the firing temperature, dew point temperature, and oxygen partial pressure in the firing step were changed to the conditions shown in Table 1 below.

[0119] [Table 1]

[0120] [Tensile strength measurement] The tensile strength of the electrode layer 2 formed on the metal support 1 was measured. Specifically, the tensile strength was measured using the following procedure.

[0121] First, a hook-shaped attachment was attached to the tip of an RS PRO force gauge (model: 111-3690), and a round eye bolt was hooked onto the tip of the hook. Then, the force gauge was fixed vertically to a platform stand whose height could be adjusted with a handle. Two screw holes were drilled in the platform part of the platform stand, allowing screws with washers to be attached. A metal support 1, with electrode layer 2 laminated in the center, was placed on the platform, and the portion of the metal support 1 where electrode layer 2 was not formed was sandwiched between washers and the platform and secured with screws. The tip of a set screw was glued to the electrode layer 2 formed on the metal support 1. A spacer was attached to the end of the set screw that was not connected to electrode layer 2, and connected to the round eye bolt hooked onto the tip of the force gauge. After that, the electrode layer 2 was pulled vertically while adjusting the height of the force gauge, and the load applied until it separated from the metal support 1 was measured. The obtained load was multiplied by the acceleration due to gravity and converted to units of Newtons. Furthermore, the area in contact with electrode layer 2 was measured using an optical microscope, and the measured area was calculated. The tensile strength N / m was calculated by dividing the load applied until delamination by the measured area. 2 The result was calculated.

[0122] The results of the tensile strength measurement are summarized in Table 1. As can be seen from Table 1, the oxygen partial pressure during firing was 4.0 × 10⁻⁶. -8 bar or more 4.0 x 10 -6 For Examples 1-7, which are below bar, the tensile strength is 1.2 MN / m² in all cases. 2 The values ​​are as high as above. In contrast, the oxygen partial pressure during firing is 4.0 × 10⁻⁶. -8 Comparative Example 1, which is less than bar, and 4.0 × 10 -6 Comparative Example 2, which is larger than bar, all exhibited extremely low tensile strengths compared to Examples 1-7.

[0123] [Formation of the middle layer] Furthermore, in Examples 1 to 7 and Comparative Examples 1 and 2, an electrode layer 2 was formed on the metal support 1 in the same manner as described above, and then an intermediate layer 3 was formed on the electrode layer 2. Specifically, first, a paste was prepared by adding an organic binder and an organic solvent (dispersion medium) to fine GDC powder. Using this paste, the intermediate layer 3 was laminated by screen printing in a region with a radius of 6 mm from the center of the metal support 1 on which the electrode layer 2 was formed. After that, the metal support 1 on which the intermediate layer 3 was laminated was subjected to compression molding and then firing to form an intermediate layer 3 with a flat surface (intermediate layer formation step).

[0124] As a result of forming the intermediate layer 3 in the intermediate layer formation step as described above, the oxygen partial pressure during firing was 4.0 × 10⁻⁶, as shown in Table 1. -8 bar or more 4.0 x 10 -6 In Examples 1 to 7, where the oxygen partial pressure during firing was below bar, no delamination of the intermediate layer 3 was observed. However, in Comparative Examples 1 and 2, where the oxygen partial pressure during firing was outside the above range, the intermediate layer 3 was delaminated. Figures 4 to 6 are images of the metal support 1 after the intermediate layer formation step. Figure 4 is an image of Example 4, and Figure 5 is an image of Example 6, showing that the intermediate layer 3 has not been delaminated. On the other hand, Figure 6 is an image of Comparative Example 2, where the white area in the image is the electrode layer 2 that appeared due to the delamination of the intermediate layer 3.

[0125] [Another embodiment] [1] In the above embodiment, the degreasing step is performed before the firing step, but the invention is not limited to this, and the degreasing step may be omitted.

[0126] [2] In the above embodiment, the dew point is set to 10°C or more and 70°C or less, the firing temperature is set to 800°C or more and 1100°C or less, and the firing is performed when the partial pressure of oxygen is 4.0 × 10 -8 bar or more 4.0 x 10 -6 The process is carried out under an atmosphere below bar, but it is not limited to this. The partial pressure of oxygen is determined by changing the dew point and firing temperature, which are parameters. Therefore, the atmosphere during firing is such that the partial pressure of oxygen is 4.0 × 10⁻⁶. -8 bar or more 4.0 x 10-6 If the oxygen partial pressure is below bar, the dew point and firing temperature do not necessarily have to be within the above range; either the dew point or the firing temperature, or both, may be set to values ​​outside the above range in order to achieve the desired oxygen partial pressure.

[0127] [3] In the above embodiment, when manufacturing the metal-supported electrochemical element E, an intermediate layer formation step and a reaction prevention layer formation step are performed so that the metal-supported electrochemical element E is equipped with an intermediate layer 3 and a reaction prevention layer 5. However, the embodiment is not limited to this, and may be equipped with an intermediate layer 3 and a reaction prevention layer 5. In the embodiment without the intermediate layer 3, the electrolyte layer 4 is formed on the electrode layer 2, and in the embodiment without the reaction prevention layer 5, the counter electrode layer 6 is formed on the electrolyte layer 4.

[0128] [4] In the above embodiment, the metal-supported electrochemical element E was used in a solid oxide fuel cell, but this metal-supported electrochemical element E can also be used in solid oxide electrolytic cells, oxygen sensors using solid oxides, and the like. When operating a metal-supported electrochemical element E as an electrolytic cell, a gas containing water vapor or carbon dioxide is passed through the electrode layer 2, and a voltage is applied between the electrode layer 2 and the counter electrode layer 6. This generates electrons e in the electrode layer 2. - It reacts with water (H2O) and carbon dioxide molecules (CO2) to produce hydrogen (H2), carbon monoxide (CO), and oxygen ions (O). 2- This is the result. Oxygen ion O 2- It moves through the electrolyte layer 4 to the counter electrode layer 6. Then, in the counter electrode layer 6, oxygen ions O 2- The electrons are released to form oxygen (O2). Through the above reaction, water (H2O) is electrolyzed into hydrogen (H2) and oxygen (O2). If a gas containing carbon dioxide molecules (CO2) is circulated, it is electrolyzed into carbon monoxide (CO) and oxygen (O2). Figure 7 shows an example of an electrochemical apparatus Y1 and energy system Z1 when a metal-supported electrochemical element E is operated as an electrolytic cell to generate gas by the electrolytic reaction described above. As shown in the figure, the energy system Z1 has an electrochemical apparatus Y1 and two heat exchangers 90 and 92 which serve as waste heat utilization units that reuse the heat circulating from the electrochemical apparatus Y1. In this embodiment, the electrochemical apparatus Y1 includes an electrochemical module M, a fuel converter 91 that synthesizes hydrocarbons based on hydrogen and the like produced in the electrochemical module M, and a power converter 93 that supplies electricity to the electrochemical module M. In this electrochemical apparatus Y1, the electrochemical module M has a plurality of metal-supported electrochemical elements E and two gas manifolds 17 and 171. The plurality of metal-supported electrochemical elements E are arranged in parallel and electrically connected to each other. One end (lower end) of the metal-supported 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 of the metal-supported electrochemical element E receives water vapor and carbon dioxide. The hydrogen and carbon monoxide produced by the above-mentioned reaction in the metal-supported electrochemical element E are collected by the gas manifold 171 which is in communication with the other end. Furthermore, in this embodiment, the heat exchanger 90 is configured to operate 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 to vaporize it, and the heat exchanger 92 is configured to operate as a waste heat utilization unit that exchanges heat between the waste heat generated by the metal-supported electrochemical element E and water vapor and carbon dioxide to preheat it, thereby increasing energy efficiency. Furthermore, the power converter 93 supplies power to the metal-supported electrochemical element E of the electrochemical module M. As a result, the metal-supported electrochemical element E acts as an electrolytic cell. Therefore, according to the above configuration, an electrochemical apparatus Y1 and energy system Z1 can be realized that can improve the efficiency of converting electrical energy into chemical energy such as fuel.

[0129] [5] In the above embodiment, multiple metal-supported electrochemical elements E are used in combination as an electrochemical module M, but the invention is not limited to this, and they can also be used individually.

[0130] [6] In the above embodiment, the energy systems Z and Z1 are provided with a waste heat utilization unit that reuses the heat discharged from the electrochemical apparatus Y and Y1, but the system is not limited to this, and may be provided without a waste heat utilization unit.

[0131] [7] In the above embodiment, composite materials such as NiO-GDC, Ni-GDC, NiO-YSZ, Ni-YSZ, CuO-CeO2, and Cu-CeO2 are used as the material for the electrode layer 2, and composite oxides such as LSCF and LSM are used as the material for the counter electrode layer 6, and hydrogen gas is flowed through the electrode layer 2 to make it a fuel electrode (anode), and air is flowed through the counter electrode layer 6 to make it an air electrode (cathode), and it is used as a power generation cell for a solid oxide fuel cell, but it is not limited to this. The metal-supported electrochemical element E may be configured in such a way that the electrode layer 2 can be an air electrode and the counter electrode layer 6 can be a fuel electrode by changing this configuration. That is, composite oxides such as LSCF and LSM are used as the material for the electrode layer 2, and composite materials such as NiO-GDC, Ni-GDC, NiO-YSZ, Ni-YSZ, CuO-CeO2, and Cu-CeO2 are used as the material for the counter electrode layer 6. With a metal-supported electrochemical element E configured in this way, air can be passed through the electrode layer 2 to form an air electrode, and hydrogen gas can be passed through the counter electrode layer 6 to form a fuel electrode, allowing the metal-supported electrochemical element E to be used as a power generation cell for a solid oxide fuel cell.

[0132] [8] In the above embodiment, the electrochemical module M is provided with a metal-supported electrochemical element E in which a cylindrical support is formed by a metal support 1 and a U-shaped member 9 attached to the back surface of the metal support 1, but it is not limited to this. For example, as shown in Figure 8, the electrochemical module M may be configured by stacking metal-supported electrochemical elements E with an inter-cell connecting member 71 in between. In this case, the inter-cell connecting member 71 is a plate-shaped member that is conductive and impermeable to gases, and has grooves 72 that are perpendicular to each other formed on its front and back surfaces. The inter-cell connecting member 71 can be made of a metal such as stainless steel or a metal oxide. When the metal-supported electrochemical elements E are stacked with the cell-to-cell connecting member 71 in between, gas can be supplied to the metal-supported electrochemical elements E through the groove 72. Specifically, the groove 72 formed on one surface becomes the first gas channel 72a, supplying gas to the front side of the metal-supported electrochemical elements E, i.e., the counter electrode layer 6. The groove 72 formed on the other surface becomes the second gas channel 72b, supplying gas to the electrode layer 2 from the back side of the metal-supported electrochemical elements E, i.e., the back side of the metal support 1, through the through hole 1a. When the electrochemical module M configured in this way is operated as a power generation cell of a solid oxide fuel cell, air is supplied to the first gas channel 72a and hydrogen is supplied to the second gas channel 72b. This causes the power generation reaction to proceed in the metal-supported electrochemical element E, generating electromotive force and current. The generated power is extracted to the outside of the electrochemical module M from the cell-to-cell connecting members 71 at both ends of the stacked metal-supported electrochemical element E. Furthermore, the grooves 72 formed on the surface and the grooves formed on the back surface of the inter-cell connecting member 71 may be parallel to each other.

[0133] [9] In the above embodiment, the metal-supported electrochemical element E was mainly used in planar or cylindrical planar solid oxide fuel cells, but it is not limited to this and can also be used in elements such as cylindrical solid oxide fuel cells.

[0134]

[10] In the above embodiment, the electrochemical apparatus Y is provided with an electrochemical module M having a plurality of metal-supported electrochemical elements E, but it is not limited to this. For example, the electrochemical apparatus may be provided with a single metal-supported electrochemical element E.

[0135] Furthermore, the configurations disclosed in the above embodiments (including other embodiments, the same applies hereinafter) can be applied in combination with configurations disclosed in other embodiments, provided that no inconsistencies arise. Moreover, 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 object of the present invention. [Explanation of symbols]

[0136] 1: Metal support 1b: Metal oxide film (diffusion prevention layer) 2: Electrode layer 3: Middle class 4: Electrolyte layer 5: Reaction prevention layer 6: Counter electrode layer 31: Desulfurizer (fuel converter) 34: Reformer (fuel converter) 38: Inverter (power converter) 53: Heat exchanger (waste heat utilization section) 90,92: Heat exchanger (waste heat utilization section) 91: Fuel Converter 93: Power Converter E: Metal-supported electrochemical element M: Electrochemical Module Y,Y1: Electrochemical apparatus Z, Z1: Energy System

Claims

1. A method for forming an electrode layer on a metal support, The electrode layer is made of at least one selected from nickel-based compounds, ceria-based compounds, zirconia-based oxides, and perovskite-based composite oxides, or a combination thereof. The electrode layer lamination step involves laminating an electrode layer on the metal support, The process includes a firing step of firing the electrode layer laminated on the metal support, The aforementioned firing step is carried out in an inert gas atmosphere with a dew point of 10°C or higher and 70°C or lower. The partial pressure of oxygen is 4.0 × 10⁻⁶ －８ bar or higher 4.0 x 10 －６ Under a bar-like atmosphere, A method for forming an electrode layer, performed at a temperature between 800°C and 1100°C.

2. The electrode layer formation method according to claim 1, wherein the inert gas is nitrogen.

3. The electrode layer forming method according to claim 1 or 2, wherein a degreasing step is performed to remove oil before the firing step.

4. The electrode layer formation method according to claim 3, wherein the degreasing step is performed at a temperature of 150°C or more and 650°C or less.

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