Method for manufacturing electrochemical element, electrochemical element, electrochemical module, solid oxide fuel cell, solid oxide electrolytic cell, electrochemical device and energy system

Abstract

To provide an electrochemical element with improved durability and performance, an electrochemical module, a solid oxide fuel cell, a solid oxide electrolytic cell, an electrochemical device, an energy system with improved durability and performance, and a method of manufacturing an electrochemical element with improved durability and performance.SOLUTION: A method of manufacturing an electrochemical element comprises: a protective layer formation step for forming a protective layer 1b on a surface where an electrode layer 2 is provided out of front and rear surfaces of a metal support 1 so that a space S which opens on the front and rear surfaces of the metal support 1 can be formed in a penetration hole 1a; and an electrode layer formation step for forming the electrode layer 2 on the metal support 1 after the protective layer formation step. The electrode layer 2 is an air electrode when a power generation reaction is caused, and an oxygen generation electrode when an electrolytic reaction is caused. In the protective layer formation step, the protective layer 1b is formed by using at least one of Co-Mn, Cu-Mn, Ni-Co-Mn, Ni-Mn, Zn-Co, Zn-Co-Mn, Co3O4, Co, Ni-Co, Co-Mn and Ni-Co-Mn as a protective material.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing an electrochemical element, an electrochemical element, an electrochemical module, a solid oxide fuel cell, a solid oxide electrolysis cell, an electrochemical device, and an energy system. [Background technology]

[0002] Currently, various research and development efforts are being conducted on electrochemical elements having electrodes, electrolytes, and porous supports for power generation applications as fuel cells, electrolysis applications as electrolysis cells, etc. In particular, research and development is being conducted on metal-supported electrochemical elements in which electrodes and electrolytes are stacked on a metal support in order to achieve thinner designs and improved robustness compared to conventional electrolyte-supported and electrode-supported electrochemical elements (see, for example, Patent Document 1). In particular, Patent Document 1 discloses a metal-supported electrochemical element in which electrodes and an electrolyte are stacked on a metal support, in which a plurality of through-holes are formed penetrating the front and back of the metal support, allowing partial gas permeation. In metal-supported electrochemical elements, the substances necessary for power generation or electrolysis are supplied to the electrodes through a porous metal support, where an electrochemical reaction occurs within the electrode to generate power or electrolysis. To achieve highly efficient electrochemical reactions, it is important to smoothly supply substances to the porous metal support. This principle is common to oxide-ion conducting and proton conducting fuel cells and electrolysis cells, regardless of the ionic conductivity of the electrolyte. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-160368 Summary of the Invention [Problem to be solved by the invention]

[0004] During operation, the metal support of an electrochemical element is exposed to an atmosphere containing feed materials and products of electrochemical reactions. Because the feed materials and products on the metal support side pass through the perforations, any disruption in the supply of feed materials or the discharge of products can lead to performance degradation and deterioration due to a decrease in gas diffusivity. In particular, in configurations where the fuel electrode is located directly above (or nearby) the metal support, the feed materials to the fuel electrode are generally used at a high utilization rate, which raises concerns about a decrease in the concentration of the feed materials, further accelerating performance degradation and deterioration. In contrast, the technology disclosed in Patent Document 1 has a configuration in which the air electrode is located directly on the metal support, thereby suppressing performance degradation and deterioration due to reduced gas diffusion to the fuel electrode. However, when a configuration in which the air electrode is stacked directly on the metal support (hereinafter sometimes referred to as inverse stacking) is adopted, there is a concern that the air electrode and the layers stacked thereon may be poisoned by element diffusion from the metal support, resulting in performance degradation and cracking. Therefore, measures to address these issues are necessary, and the development of a new technology has been desired.

[0005] The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to provide 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 with improved durability and performance. [Means for solving the problem]

[0006] A method for producing an electrochemical element to achieve the above object includes the steps of: A method for manufacturing an electrochemical device in which an electrode layer is formed on a metal support having through-holes, the method comprising the steps of: a protective layer forming step of forming a protective layer on one of the front and rear surfaces of the metal support, on which the electrode layer is to be provided, so that a space opening to the front and rear surfaces of the metal support is formed in the through hole; an electrode layer forming step of forming the electrode layer on the metal support after the protective layer forming step, the electrode layer serves as an air electrode when a power generation reaction occurs, and serves as an oxygen evolution electrode when an electrolysis reaction occurs; In the protective layer forming step, the protective layer is formed using at least one of Co-Mn, Cu-Mn, Ni-Co-Mn, Ni-Mn, Zn-Co, Zn-Co-Mn, Co3O4, Co, Ni-Co, Co-Mn, and Ni-Co-Mn as a protective material.

[0007] According to the above-described characteristic configuration, by performing the protective layer forming step, a protective layer is formed on the surface of the metal support on which the electrode layer is to be provided, out of the front and rear surfaces of the metal support, and therefore, during the manufacture of the electrochemical element or during the operation of a device such as a fuel cell or electrolysis cell that includes the electrochemical element as a component, the material of the metal support (e.g., Cr) is less likely to scatter from the metal support to the electrode layer, thereby improving the durability of the manufactured electrochemical element. In particular, the inventors of the present invention have discovered that by forming a protective layer using at least one of Co-Mn, Cu-Mn, Ni-Co-Mn, Ni-Mn, Zn-Co, Zn-Co-Mn, Co3O4, Co, Ni-Co, Co-Mn, and Ni-Co-Mn as a protective material in the protective layer formation step, it is possible to suppress the diffusion of Cr and other elements from the metal support to the electrode layer and to suppress the generation of a high-resistance layer (especially SrCrO4), thereby suppressing deterioration and cracking of the electrode layer and other layers stacked on the metal support and effectively suppressing an increase in resistance. The reason for this is thought to be that the use of the above-mentioned protective material results in the metal substrate surface being covered with a dense film. As a result, a method for manufacturing an electrochemical device with improved durability and performance can be realized.

[0008] A further characteristic configuration of the method for manufacturing an electrochemical element is as follows: The protective layer forming step is characterized in that the protective layer is formed on the entire surface of the metal support.

[0009] According to the above-described characteristic configuration, the entire surface of the metal support is covered with a protective layer. Therefore, deterioration of the entire surface of the metal support is suppressed. Furthermore, since the protective layer is also formed between the metal support and the electrode layer formed on the metal support, scattering of Cr from the metal support to the electrode side can be effectively prevented, and the generation of a high-resistance layer (especially SrCrO4) between the metal support and the electrode layer can also be effectively suppressed. This further improves the durability and performance of the manufactured electrochemical element.

[0010] A further characteristic configuration of the method for manufacturing an electrochemical element is as follows: In the protective layer forming step, the protective layer is formed using at least one of Co-Mn, Cu-Mn, Ni-Co-Mn, Ni-Mn, Zn-Co, Zn-Co-Mn, and Co3O4 as the protective material in the electrodeposition coating method, and at least one of Co, Ni-Co, Co-Mn, and Ni-Co-Mn as the protective material in the plating coating method.

[0011] As described above, in the electrodeposition coating method, it is preferable to use at least one of Co-Mn, Cu-Mn, Ni-Co-Mn, Ni-Mn, Zn-Co, Zn-Co-Mn, and Co3O4 as the protective material, and in the plating coating method, it is preferable to use at least one of Co, Ni-Co, Co-Mn, and Ni-Co-Mn as the protective material. This covers the surface of the metal substrate with a dense film, which prevents, for example, scattering of elements that make up the metal support. Similarly, oxygen diffusion is suppressed, which also suppresses the growth of high-resistance layers such as Cr2O3, thereby suppressing an increase in IR resistance.

[0012] The electrochemical element for achieving the above object has the following characteristic configuration: a metal support having a through hole; an electrode layer disposed on the metal support; a protective layer formed on one of the front and rear surfaces of the metal support on which the electrode layer is to be provided, a space that is open to the front and back surfaces of the metal support is formed in the through hole, the electrode layer serves as an air electrode when a power generation reaction occurs, and serves as an oxygen evolution electrode when an electrolysis reaction occurs; The protective layer is made of at least one protective material selected from the group consisting of Co-Mn, Cu-Mn, Ni-Co-Mn, Ni-Mn, Zn-Co, Zn-Co-Mn, Co3O4, Co, Ni-Co, Co-Mn, and Ni-Co-Mn.

[0013] According to the above-mentioned characteristic configuration, a protective layer is formed on the surface of the metal support on which the electrode layer is provided, and therefore, during operation of a device such as a fuel cell or electrolysis cell that includes the electrochemical element as a component, the material of the metal support (e.g., Cr) is less likely to scatter from the metal support to the electrode layer, resulting in an electrochemical element with improved durability. In particular, the inventors of the present invention have discovered that by forming a protective layer using at least one of Co-Mn, Cu-Mn, Ni-Co-Mn, Ni-Mn, Zn-Co, Zn-Co-Mn, Co3O4, Co, Ni-Co, Co-Mn, and Ni-Co-Mn as a protective material in the protective layer formation step, it is possible to suppress the diffusion of Cr and other elements from the metal support to the electrode layer and to suppress the generation of a high-resistance layer (especially SrCrO4), thereby suppressing deterioration and cracking of the electrode layer and other layers stacked on the metal support and effectively suppressing an increase in resistance. The reason for this is thought to be that the surface of the metal substrate is covered with a dense film. As a result, an electrochemical device with improved durability and performance can be realized.

[0014] Further characteristic configurations of the electrochemical element include: The protective layer is formed on the entire surface of the metal support.

[0015] According to the above-described characteristic configuration, the entire surface of the metal support is covered with a protective layer. Therefore, deterioration of the entire surface of the metal support is suppressed. Furthermore, since the protective layer is also formed between the metal support and the electrode layer formed on the metal support, scattering of Cr from the metal support to the electrode side can be effectively prevented, and the generation of a high-resistance layer (especially SrCrO4) between the metal support and the electrode layer can also be effectively suppressed. This further improves the durability and performance of the manufactured electrochemical element.

[0016] Further characteristic configurations of the electrochemical element include: an electrolyte layer disposed on the electrode layer; and a counter electrode layer disposed on the electrolyte layer.

[0017] According to the above characteristic configuration, the electrochemical device has excellent durability and performance.

[0018] Further characteristic configurations of the electrochemical element include: The electrolytic capacitor further includes an intermediate layer disposed between the electrode layer and the electrolyte layer.

[0019] According to the above characteristic configuration, it is possible to effectively suppress the reaction between the constituent material of the electrode layer and the constituent material of the electrolyte layer, and to improve the long-term stability of the performance of the electrochemical element.

[0020] Further characteristic configurations of the electrochemical element include: After a durability test is conducted in which the electrode layer is exposed to an atmospheric atmosphere in the operating temperature range for a predetermined durability test period, a cross section perpendicular to the front and back surfaces is analyzed by energy dispersive X-ray spectroscopy, and the Cr content in the electrode layer is found to be below the detection limit.

[0021] According to the above-described characteristic configuration, after a durability test, the analysis results obtained by energy dispersive X-ray spectroscopy show that the Cr content in the electrode layer is below the detection limit. This suppresses deterioration of the electrode layer and other layers stacked on the metal support, thereby realizing an electrochemical element that is expected to have improved durability.

[0022] Further characteristic configurations of the electrochemical element include: After a durability test is conducted in which the product is exposed to an atmospheric atmosphere in the operating temperature range for a predetermined durability test period, a cross section perpendicular to the front and back surfaces is analyzed by energy dispersive X-ray spectroscopy, and the results show that the amount of high-resistance material between the metal support and the electrode layer is below the detection standard.

[0023] According to the above characteristic configuration, after a durability test, the analysis results obtained by energy dispersive X-ray spectroscopy show that the amount of high-resistance material between the metal support and the electrode layer is below the detection standard, thereby suppressing voltage drop and realizing an electrochemical element that is expected to have improved performance.

[0024] In order to achieve the above-mentioned object, the electrochemical module is preferably arranged in a state where a plurality of electrochemical elements are assembled.

[0025] According to the above-described characteristic configuration, by arranging a plurality of electrochemical elements in a cluster, it is possible to realize a compact, high-performance electrochemical module that is excellent in durability and performance while reducing material and processing costs. Furthermore, when the electrochemical module is operated as a fuel cell, for example, it is possible to obtain a large power output.

[0026] The characteristic configuration of a solid oxide fuel cell to achieve the above-mentioned object is as follows: The present invention is characterized in that it comprises the above-mentioned electrochemical element, and causes a power generation reaction in the electrochemical element.

[0027] According to the above characteristic configuration, a power generation reaction can be carried out in a solid oxide fuel cell provided with an electrochemical element having excellent durability, and therefore a highly durable solid oxide fuel cell can be obtained.

[0028] The solid oxide electrolysis cell for achieving the above-mentioned object has the following characteristic configuration: The present invention is characterized in that the electrochemical element is provided and an electrolytic reaction occurs in the electrochemical element.

[0029] According to the above characteristic configuration, a solid oxide electrolysis cell including an electrochemical element with excellent durability and performance can be used to generate gas through an electrolytic reaction, and therefore a highly durable and high-performance solid oxide electrolysis cell can be obtained.

[0030] The electrochemical device for achieving the above object has the following characteristic configuration: the electrochemical element or the electrochemical module described above; and a fuel converter that generates a reducing component to be supplied to the electrochemical element or the electrochemical module, or that converts a gas containing a reducing component generated in the electrochemical element or the electrochemical module.

[0031] According to the above-described characteristic configuration, when the electrochemical element or electrochemical module is operated as a fuel cell, it can be configured to generate hydrogen using a fuel converter such as a reformer from natural gas or the like supplied using an existing raw fuel supply infrastructure such as city gas, thereby realizing an electrochemical device equipped with an electrochemical element or electrochemical module with excellent durability. Furthermore, it becomes easier to build a system for recycling unused fuel gas circulated from the electrochemical module, thereby realizing a highly efficient electrochemical device. On the other hand, when the electrochemical element or electrochemical module is operated as an electrolysis 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. Then, electrons e - reacts with water H2O and carbon dioxide molecules CO2 to produce hydrogen H2, carbon monoxide CO and oxygen ions O 2- The generated oxygen ions O 2- moves through the electrolyte layer to the counter electrode layer, where oxygen ions O 2- releases electrons and becomes oxygen O2. Through the above reaction, when gas containing water vapor flows, water H2O is decomposed into hydrogen H2 and oxygen O2, and when gas containing carbon dioxide molecules CO2 flows, 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 the hydrogen and carbon monoxide produced by the electrolysis in the electrochemical element or electrochemical module. This allows the hydrocarbons produced by the fuel converter to be circulated to the electrochemical element or electrochemical module, or extracted from this system / device and used as fuel or chemical raw materials.

[0032] The electrochemical device for achieving the above object has the following characteristic configuration: the electrochemical element or the electrochemical module described above; and a power converter that extracts electric power from the electrochemical element or the electrochemical module, or that supplies electric power to the electrochemical element or the electrochemical module.

[0033] According to the above characteristic configuration, the power converter can extract power generated by the electrochemical element or electrochemical module, or can distribute power to the electrochemical element or electrochemical module. As a result, the electrochemical element or electrochemical module functions as a fuel cell or an electrolytic cell. Therefore, according to the above characteristic configuration, an electrochemical device can be realized with improved efficiency in converting chemical energy, such as fuel, into electrical energy, or converting electrical energy into chemical energy, such as fuel. For example, when an inverter is used as the power converter, it is preferable when operating as a fuel cell, because the inverter can boost the voltage or convert direct current to alternating current, making it easier to utilize the electrical output obtained from the electrochemical element or electrochemical module. Furthermore, when operating as an electrolytic cell, it is preferable to construct an electrochemical device that can obtain direct current from an alternating current power source and supply the direct current to the electrochemical element or electrochemical module.

[0034] The characteristic configuration of the energy system to achieve the above-mentioned objectives is as follows: the electrochemical device described above; and a waste heat utilization unit that reuses the heat discharged from the electrochemical device.

[0035] The above-described characteristic configuration makes it possible to realize an energy system that is both highly durable and highly energy efficient. It is also possible to realize a hybrid system with excellent energy efficiency by combining the above-described configuration with a power generation system that generates electricity by utilizing the combustion heat of unused fuel gas discharged from the electrochemical device. [Brief explanation of the drawings]

[0036] [Figure 1] 1 is a diagram showing a schematic configuration of a metal-supported electrochemical element according to one embodiment. [Figure 2] 1 is a diagram showing a schematic configuration of an electrochemical module according to an embodiment. [Figure 3] 1 is a diagram showing a schematic configuration of an electrochemical device and an energy system according to an embodiment. [Figure 4] FIG. 1 is a graph showing the current-voltage characteristics of metal-supported electrochemical elements according to an example and a comparative example. [Figure 5] 1 is an electron microscope photograph (EDX result: O) of a metal-supported electrochemical element according to an example. [Figure 6] 1 is an electron microscope photograph (EDX result: Cr) of a metal-supported electrochemical element according to an example. [Figure 7] 1 is an electron microscope photograph (EDX result: Sr) of a metal-supported electrochemical element according to an example. [Figure 8] 1 is an electron microscope photograph (EDX result: O) of a metal-supported electrochemical element according to a comparative example. [Figure 9] 1 is an electron microscope photograph (EDX result: Cr) of a metal-supported electrochemical element according to a comparative example. [Figure 10] 1 is an electron microscope photograph (EDX result: Sr) of a metal-supported electrochemical element according to a comparative example. [Figure 11] FIG. 10 is a diagram showing a schematic configuration of an electrochemical device and an energy system according to another embodiment. [Figure 12]FIG. 10 is a diagram showing a schematic configuration of an electrochemical module according to another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0037] Hereinafter, a method for manufacturing a metal-supported electrochemical element E according to an embodiment, a metal-supported electrochemical element E, a solid oxide fuel cell (SOFC), an electrochemical module M, an electrochemical device Y, and an energy system Z will be described. In this embodiment, the metal-supported electrochemical element E is used as a component of a solid oxide fuel cell that generates electricity when supplied with a fuel gas containing hydrogen and air (oxidant gas). Hereinafter, when describing the positional relationship between layers, the side of the counter electrode layer 6 as viewed from the electrolyte layer 4 may be referred to as "top" or "upper side," and the side of the electrode layer 2 may be referred to as "bottom" or "lower side." The surface of the metal support 1 on which the electrode layer 2 is formed may be referred to as the "front surface," and the opposite surface as the "rear surface." Hereinafter, the front surface of the metal support 1 corresponds to the "front surface," and the rear surface corresponds to the "rear surface."

[0038] (electrochemical element) As shown in Fig. 1, the metal-supported electrochemical element E is a metal-supported electrochemical element having a metal support 1, a protective layer 1b formed on the entire surface of the 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.

[0039] (metal support) The metal support 1 supports the electrode layer 2, the intermediate layer 3, the electrolyte layer 4, the reaction prevention layer 5, and the counter electrode layer 6, thereby maintaining the strength of the metal-supported electrochemical element E. In other words, the metal support 1 serves as a support for supporting the components of the electrochemical element.

[0040] The metal support 1 is made of a material having excellent electronic conductivity, heat resistance, oxidation resistance, and corrosion resistance. Examples of suitable materials include ferritic stainless steel, austenitic stainless steel, and nickel-based alloys. In particular, alloys containing chromium are preferred. In this embodiment, the metal support 1 is made of an Fe—Cr alloy containing 18 to 25% by mass of Cr. However, particularly preferred are an Fe—Cr alloy containing 0.05% by mass or more 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 content of Ti and Zr of 0.15 to 1.0% by mass, and an Fe—Cr alloy containing 0.10 to 1.0% by mass of Cu. It is preferable that the metal support 1 be made of a ferritic stainless steel material, since this allows for the realization of an inexpensive, high-strength metal-supported electrochemical element.

[0041] The metal support 1 has a plate shape as a whole. 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, the thickness thereof is preferably, for example, 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 cost reduction, the thickness thereof is preferably, for example, 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 penetrating 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 having a plurality of through-holes 1a formed by mechanical, chemical, or optical perforation (hole processing) such as punching, etching, or laser processing so as to penetrate the front and back surfaces of the metal plate. This allows for 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. In addition, when the through hole 1a is perforated by a laser, the hole diameter T1 can be approximately 0.5 μm or more and 100 μm or less, preferably 0.5 μm or more and 80 μm or less, and more preferably 0.5 μm or more and 50 μm or less, and when the through hole 1a is perforated by punching, the hole diameter T1 can be approximately 100 μm or more and 500 μm or less, preferably 150 μm or more and 450 μm or less, and more preferably 200 μm or more and 400 μm or less. The plate-shaped metal support 1 can also be bent and deformed into a box-like, cylindrical or other shape for use.

[0042] (protective layer) A protective layer 1b is provided on the entire surface of the metal support 1. Specifically, the protective layer 1b is provided on the front, back, and side surfaces of the metal support 1 and the inner walls of the through-holes 1a. Therefore, during operation of a device such as a fuel cell or electrolysis cell that includes the metal-supported electrochemical element E as a component, the inner walls of the through-holes 1a in the metal support 1, the edge portions D at the openings of the through-holes 1a, and the front and back surfaces of the metal support 1 are protected from exposure to high-temperature gas and are less likely to deteriorate. In other words, the metal-supported electrochemical element E has improved durability. Furthermore, the protective layer 1b is formed so as to form a space S within the through-holes 1a that opens to the front and back surfaces (front and back surfaces) of the metal support 1. Therefore, in the metal-supported electrochemical element E, gas can flow through the space S, making it easier for power generation reactions and electrolysis reactions to occur. As a result, the metal-supported electrochemical element E has improved performance. From the viewpoint of protecting the front and rear surfaces of the metal support 1 from exposure to high-temperature gas without impairing the gas permeability at the openings of the through holes 1a, the thickness T2 of the protective layer 1b is preferably 3 μm to 20 μm, more preferably 5 μm to 15 μm, in the case of electrolytic coating described later. Furthermore, in the case of coating by plating treatment described later, the thickness T2 is preferably 2 μm to 6 μm, more preferably 2 μm to 4 μm.

[0043] In the electrodeposition coating method described below, the protective layer 1b is made of at least one of Co-Mn, Cu-Mn, Ni-Co-Mn, Ni-Mn, Zn-Co, Zn-Co-Mn, and Co3O4, while in the plating coating method including a plating treatment described below, the protective layer 1b is made of at least one of Co, Ni-Co, Co-Mn, and Ni-Co-Mn. As a result, as shown in the test results described below, it is possible to suppress the diffusion of Cr and the like from the metal support 1 to the electrode layer 2 and to suppress the generation of a high-resistance layer (especially a layer made of SrCrO4, for example, having a higher resistance value than the metal support 1). This prevents deterioration and cracking of the electrode layer 2 and the like laminated on the metal support 1 and effectively suppresses an increase in resistance.

[0044] [Items to be noted regarding item 2-02] The protective layer 1b can be formed by various methods including PVD coating and spray coating, but can also be formed by a known plating coating method or the electrodeposition coating method described below. Electrodeposition coating is performed, for example, by completely or partially immersing the metal substrate 1 as the anode in a current-carrying tank filled with a mixed solution (a mixed solution containing 100 g of particles of the protective material described above dispersed per liter of the electrodeposition solution and an anionic resin such as polyacrylic acid) and applying current. The electrodeposition coating conditions are not particularly limited and can be appropriately selected from a wide range depending on various conditions, such as the type of metal forming the metal substrate 1, the type of mixed solution, the size and shape of the current-carrying tank, and the intended use of the resulting metal substrate 1. Typically, the bath temperature (mixed solution temperature) is approximately 10 to 40°C, the applied voltage is approximately 10 to 450 V, the voltage application time is approximately 1 to 10 minutes, and the mixed solution temperature is 10 to 40°C. The thickness of the electrodeposition coating film can be controlled by changing the electrodeposition voltage and electrodeposition time. Various pretreatments can also be performed on the metal substrate 1. A cured electrodeposition coating film is formed on the surface of the metal substrate 1 by heat-treating the metal substrate 1 with the uncured electrodeposition coating formed thereon. The heat treatment includes pre-drying to dry the electrodeposition coating film and curing heating to harden the electrodeposition coating film, and the pre-drying is followed by curing heating. After that, the metal support 1 with the protective material adhered to its surface and hardened is fired in an electric furnace and then slowly cooled to form a protective layer 1b on the surface. The firing treatment for forming the protective layer 1b is preferably performed at a low temperature of 1100° C. or less. This is preferable because it prevents damage to the metal support 1 during the formation of the protective layer 1b, and also makes it possible to suppress element diffusion between the metal support 1 and the protective layer 1b, thereby realizing a metal-supported electrochemical element with excellent durability.

[0045] (electrode layer) As shown in FIG. 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 of the metal support 1 where the through holes 1 a are formed. When the electrode layer 2 is a thin layer, the 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 electrode layer material used, thereby reducing costs, while ensuring sufficient electrode performance. Furthermore, the region of the metal support 1 where the through holes 1 a are formed is entirely covered with the electrode layer 2. In other words, the through holes 1 a are formed inside the region of the metal support 1 where the electrode layer 2 is formed. In other words, all of the through holes 1 a are provided facing the electrode layer 2.

[0046] Examples of materials that can be used for the electrode layer 2 include composite oxides such as LSCF and LSM, ceria-based oxides, and mixtures thereof. In particular, the electrode layer 2 preferably contains a perovskite-type oxide containing two or more elements selected from the group consisting of La, Sr, Sm, Mn, Co, and Fe. The electrode layer 2 formed using the above materials functions as a cathode (air electrode).

[0047] The electrode layer 2 is preferably formed using a method capable of forming the electrode layer 2 at a processing temperature of 1100°C or less, since this method can suppress damage to the metal support 1 and element 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, low-temperature firing (e.g., a wet method using firing at a low temperature without firing at a high temperature exceeding 1100°C), spray coating (thermal spraying, aerosol deposition, aerosol gas deposition, powder jet deposition, particle jet deposition, cold spray, etc.), PDV (sputtering, pulsed laser deposition, etc.), CVD, etc., can be used as appropriate. Low-temperature firing and spray coating methods are particularly preferred, as they allow for low-cost elements to be realized. Furthermore, low-temperature firing is even more preferred, as it facilitates handling of raw materials.

[0048] The electrode layer 2 has a plurality of pores inside and on its surface to provide gas permeability. That is, the electrode layer 2 is formed as a porous layer. From the viewpoint of forming a three-dimensional gas diffusion path, the porosity of the electrode layer 2 is preferably 5% or more, and more preferably 5% to 60%. The electrode layer 2 is formed, for example, so that its density is greater than 40% and less than 95%. The size of the pores can be appropriately selected to ensure smooth progress of the electrochemical reaction. The density is the proportion of the space occupied by the material constituting the layer, and can be expressed as (1 - porosity), and is equivalent to the relative density.

[0049] (middle class) As shown in FIG. 1 , the intermediate layer 3 can be formed as a thin layer on the electrode layer 2, covering the electrode layer 2. In this way, the intermediate layer 3 is disposed between the porous electrode layer 2, continuously connecting the two to form a dense electrolyte layer 4 on the porous electrode layer 2, and serves as a buffer layer that relieves various stresses applied during the manufacture and operation of the metal-supported electrochemical element E. Therefore, the intermediate layer 3 is intentionally formed to have a smaller density than the electrolyte layer 4. Alternatively, the intermediate layer 3 is intentionally formed to have a larger density than the electrode layer 2. This allows the intermediate layer 3 to absorb and relieve various stresses between the layers, even when the porous electrode layer 2 and the dense electrolyte layer 4 are formed on the metal support 1, thereby improving the performance, reliability, and stability of the metal-supported electrochemical element E. When the intermediate layer is 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 reducing costs, while still ensuring sufficient performance.

[0050] Examples of materials that can be used for the intermediate layer 3 include YSZ (yttria-stabilized zirconia), SSZ (scandium-stabilized zirconia), GDC (gadolinium-doped ceria), YDC (yttrium-doped ceria), and SDC (samarium-doped ceria). Ceria-based ceramics are particularly suitable.

[0051] The intermediate layer 3 is preferably formed by a low-temperature firing method (e.g., a wet method using firing in a low-temperature range without firing at a high temperature above 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. These film-forming processes that can be used in a low-temperature range can provide the intermediate layer 3 without firing at a high temperature above 1100°C. This prevents interdiffusion of elements between the metal support 1 and the electrode layer 2 without damaging the metal support 1, thereby achieving a metal-supported electrochemical element E with excellent durability. Furthermore, a low-temperature firing method is more preferable because it facilitates handling of raw materials.

[0052] In this embodiment, the intermediate layer 3 is preferably an oxygen ion (oxide ion) conductor or a mixed conductor having both oxygen ion (oxide ion) and electron conductivity. An intermediate layer 3 having such properties is suitable for application to a metal-supported electrochemical element E.

[0053] (electrolyte layer) As shown in FIG. 1, the electrolyte layer 4 is formed as a thin layer on the intermediate layer 3. Alternatively, it may be formed as a thin film having a thickness of 10 μm or less. In this embodiment, the electrolyte layer 4 is provided over (straddles) the intermediate layer 3 and the metal support 1. By configuring it in this way and joining the electrolyte layer 4 to the metal support 1, the metal-supported electrochemical element E can be made to have excellent robustness as a whole.

[0054] 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-holes 1a are provided. In other words, the through-holes 1a are 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. Specifically, when the metal-supported electrochemical element E is used as a component of an SOFC, gas is supplied to the electrode layer 2 from the back side of the metal support 1 through the through-holes 1a during SOFC operation. Gas leakage can be suppressed at the portion where the electrolyte layer 4 contacts the metal support 1 without providing a separate member such as a gasket. Note that in this embodiment, the electrolyte layer 4 completely covers the periphery of the electrode layer 2; however, the electrolyte layer 4 may be provided on top of the electrode layer 2 and the intermediate layer 3, with a gasket or the like provided around the periphery.

[0055] The electrolyte layer 4 can be made of oxygen ion-conducting electrolyte materials such as YSZ (yttria-stabilized zirconia), SSZ (scandium-stabilized zirconia), GDC (gadolinium-doped ceria), YDC (yttrium-doped ceria), SDC (samarium-doped ceria), or LSGM (strontium-magnesium-doped lanthanum gallate), or hydrogen ion-conducting electrolyte materials such as perovskite-type oxides. Zirconia-based ceramics are particularly suitable. Using zirconia-based ceramics for the electrolyte layer 4 can increase the operating temperature of an SOFC using a metal-supported electrochemical element E compared to ceria-based ceramics or various hydrogen ion-conducting materials. For example, when the metal-supported electrochemical element E is used in an SOFC as in this embodiment, a material such as YSZ that can exhibit high electrolyte performance even at high temperatures of about 650°C or higher is used as the material for the electrolyte layer 4, and a hydrocarbon-based raw fuel such as city gas or LPG is used as the raw fuel for the system, and the raw fuel is converted into SOFC anode gas by steam reforming or the like, thereby making it possible to construct a highly efficient SOFC system in which the heat generated in the SOFC cell stack is used to reform the raw fuel gas. In this embodiment, the electrolyte layer 4 contains stabilized zirconia.

[0056] The electrolyte layer 4 is preferably formed by a low-temperature firing method (e.g., a wet method using firing at a low temperature without firing at a high temperature above 1100°C), a spray coating method (thermal spraying, aerosol deposition, aerosol gas deposition, powder jet deposition, particle jet deposition, cold spray, etc.), a PVD method (sputtering, pulsed laser deposition, etc.), a CVD method, etc. These film formation processes that can be used in a low-temperature range can produce a dense electrolyte layer 4 with high airtightness and gas barrier properties without firing at a high temperature above 1100°C, for example. This can suppress damage to the metal support 1 and also suppress element diffusion between the metal support 1 and the electrode layer 2, thereby realizing a metal-supported electrochemical element E with excellent performance and durability. In particular, low-temperature firing methods and spray coating methods are preferred because they enable low-cost elements to be realized. Furthermore, spray coating is even more preferred because it can easily produce a dense electrolyte layer 4 with high airtightness and gas barrier properties at a low temperature.

[0057] The electrolyte layer 4 is densely configured to prevent gas leakage of anode gas and cathode gas and to exhibit high ionic conductivity. The density of the electrolyte layer 4 is preferably 90% or more, more preferably 95% or more, and even more preferably 98% or more. When the electrolyte layer 4 is a uniform layer, the density thereof is preferably 95% or more, and more preferably 98% or more. Furthermore, when the electrolyte layer 4 is configured as a multi-layer structure, it is preferable that at least a portion of the layers contains a layer (a dense electrolyte layer) having a density of 98% or more, and more preferably a layer (a dense electrolyte layer) having a density of 99% or more. When such a dense electrolyte layer is included as part of the electrolyte layer, it is easier to form an electrolyte layer 4 that is dense and has high airtightness and gas barrier properties, even when the electrolyte layer 4 is configured as a multi-layer structure.

[0058] (Reaction prevention layer) The reaction prevention layer 5 can be formed as a thin layer on the electrolyte layer 4. When the reaction prevention layer 5 is 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. Such a thickness makes it possible to reduce the amount of expensive reaction prevention layer material used, thereby reducing costs, while ensuring sufficient performance.

[0059] The material for the reaction prevention layer 5 may be any material that can prevent a reaction between the components of the electrolyte layer 4 and the components of the counter electrode layer 6, such as a ceria-based material. A material containing at least one element selected from the group consisting of Sm, Gd, and Y is preferably used for the reaction prevention layer 5. It is preferable that the reaction prevention layer 5 contains at least one element selected from the group consisting of Sm, Gd, and Y, and that the total content of these elements is 1.0% by mass or more and 10% by mass or less. By providing the reaction prevention layer 5 between the electrolyte layer 4 and the counter electrode layer 6, a reaction between the constituent materials of the counter electrode layer 6 and the electrolyte layer 4 is effectively suppressed, thereby improving the long-term stability of the performance of the metal-supported electrochemical element E.

[0060] The reaction prevention layer 5 preferably has oxygen ion (oxide ion) conductivity. It is more preferable that the reaction prevention layer 5 is a mixed conductor having both oxygen ion (oxide ion) and electron conductivity. The reaction prevention layer 5 having such properties is suitable for application to the metal-supported electrochemical element E.

[0061] The reaction prevention layer 5 is preferably formed using a method capable of forming the layer at a processing temperature of 1100°C or less, since this prevents damage to the metal support 1 and also prevents element diffusion between the metal support 1 and the electrode layer 2, resulting in a metal-supported electrochemical element E with excellent performance and durability. For example, low-temperature firing (e.g., a wet method using firing at a low temperature without firing at a high temperature exceeding 1100°C), spray coating (thermal spraying, aerosol deposition, aerosol gas deposition, powder jet deposition, particle jet deposition, cold spray, etc.), PVD (sputtering, pulsed laser deposition, etc.), CVD, etc., can be used. Low-temperature firing and spray coating methods are particularly preferred, as they allow for low-cost elements to be realized. Furthermore, low-temperature firing is even more preferred, as it facilitates handling of raw materials.

[0062] (Counter electrode layer) The counter electrode layer 6 can be formed as a thin layer on the reaction prevention layer 5. When the counter electrode layer 6 is formed as a thin layer, its thickness can be, for example, about 1 μm to 100 μm, and preferably 5 μm to 50 μm. Such a thickness makes it possible to reduce the amount of expensive counter electrode layer material used, thereby reducing costs, while ensuring sufficient electrode performance.

[0063] The counter electrode layer 6 can be made of a combination of at least one of a nickel-based compound and a cobalt-based compound with at least one of a ceria-based oxide and a zirconia-based oxide. For example, composites such as Ni-GDC, Ni-SDC, NiO-YSZ, and Ni-YSZ can be used. In these examples, GDC and YSZ can be called aggregates of the composite. The counter electrode layer 6 made of the above materials functions as an anode (fuel electrode). The use of these materials forms a nanocomposite structure, providing the counter electrode layer 6 with sufficient electrode performance.

[0064] The counter electrode layer 6 is preferably formed by a low-temperature firing method (e.g., a wet method using firing at a low temperature without firing at a high temperature above 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. These processes, which can be used at low temperatures, can provide a good counter electrode layer 6 without firing at a high temperature above 1100°C. This is preferable because it prevents damage to the metal support 1 and suppresses element diffusion between the metal support 1 and the electrode layer 2, resulting in a metal-supported electrochemical element with excellent durability. Furthermore, using a low-temperature firing method is even more preferable because it facilitates handling of raw materials.

[0065] (Metal-supported electrochemical element manufacturing method) 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 a protective layer forming step, an electrode layer forming step, an intermediate layer forming step, an electrolyte layer forming step, a reaction prevention layer forming step, and a counter electrode layer forming step. Furthermore, the electrode layer forming step includes at least a coating step and a firing step.

[0066] (Protective layer formation step) In the protective layer forming step, the above-mentioned electrodeposition coating method or plating coating method is used to form the protective layer 1b in a thin film state on the metal support 1. The above-mentioned methods can be used to form the protective layer 1b, but from the viewpoint of forming the protective layer 1b on the entire surface of the metal support 1 while suppressing deterioration of the metal support 1, it is preferable to use a method that can form the protective layer 1b in a low temperature range of 1100°C or less.

[0067] (Electrode layer formation step) In the electrode layer formation step, the electrode layer 2 is formed in a thin film state on the metal support 1. The electrode layer 2 can be formed using the film formation method described above, but in order to suppress 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.

[0068] When the electrode layer forming step is performed by a low-temperature firing method, the step is specifically performed as follows.

[0069] First, a material paste is prepared by mixing the material powder of the electrode layer 2 with a solvent (dispersion medium) (electrode layer preparation step). In the electrode layer preparation step, the material paste for the electrode layer is adjusted so that its viscosity is higher than the viscosity of the material paste for the protective layer. In other words, the viscosity of the material paste for the protective layer is adjusted so that its viscosity is lower than the viscosity of the material paste for the electrode layer.

[0070] Next, the prepared paste is applied to the surface (front surface) of the metal support 1 on which the protective layer 1b has been formed (application step).

[0071] Next, the applied paste layer is compressed (compression step). Compression of the paste layer (compression molding) can be performed by, for example, CIP (Cold Isostatic Pressing), roll pressing, RIP (Rubber Isostatic Pressing), or the like. This step may be omitted. That is, the applied paste layer may not be compressed, and the electrode layer 2 fired in the firing step may be compressed later.

[0072] A degreasing step is carried out to remove oil. The degreasing step is preferably a process of heating the metal support 1 at a temperature of 150°C or higher and 650°C or lower. By carrying out the degreasing step, it is possible to prevent poor film formation of the electrode layer 2 due to contamination such as oil and grease. Note that the degreasing step can be omitted.

[0073] Thereafter, the metal support 1 on which the paste has been applied is fired (firing step). As a result, a protective layer 1b is formed on the entire surface of the metal support 1 in the protective layer forming step, and an electrode layer 2 is formed on the metal support 1 on which the protective layer 1b has been formed in the application step. The firing step is carried out at a temperature of 800°C or higher and 1100°C or lower in order to prevent deterioration of the metal support 1. In particular, it is preferable to carry out the firing step at 1050°C or lower, and more preferably at 1000°C or lower. The firing step is carried out at a temperature of 800°C or higher and 1100°C or lower in order to prevent deterioration of the metal support 1. -8 bar or more 4.0 × 10 -6 The firing step is carried out in an atmosphere adjusted so that the oxygen partial pressure is 4.0 × 10 bar or less. -8 bar or more 4.0 × 10 -6 By performing the process under an atmosphere of 7.5×10 bar or less, a strong protective layer 1b and an electrode layer 2 can be formed without using hydrogen. -8 bar or more 3.0 × 10 -6 Preferably, the temperature is 2.9 × 10 -7 bar or more 1.5 × 10 -6 It is more preferable that the temperature is equal to or less than 1 bar.

[0074] A smoothing step for smoothing the surface of the electrode layer 2 may be performed before or after the firing step. The smoothing step may be performed by lapping, leveling, cutting or polishing the surface, etc. The smoothing of the surface of the electrode layer 2 may also be achieved by a compression step.

[0075] (Intermediate layer formation step) In the intermediate layer formation step, the intermediate layer 3 is formed in a thin layer state on the protective layer 1b and the electrode layer 2 so as to cover the electrode layer 2. The intermediate layer 3 can be formed using the above-mentioned film formation method, but in order to suppress 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.

[0076] When the intermediate layer formation step is performed using a low-temperature firing method, the step is specifically performed as follows. First, a material powder for the intermediate layer 3 is mixed with a solvent (dispersion medium) to prepare a material paste, which is then applied to the front surface of the electrode layer 2. The intermediate layer 3 is then compression-molded (intermediate layer smoothing step, compression step) and fired at 1100°C or less (intermediate layer firing step). The compression molding of the intermediate layer 3 can be performed, for example, by CIP molding, roll pressure molding, RIP molding, or the like. Furthermore, the firing of the intermediate layer 3 is preferably performed at a temperature of 800°C or higher and 1100°C or lower. This is because such a temperature can form a high-strength intermediate layer 3 while suppressing damage and deterioration of the metal support 1. Furthermore, the firing of the intermediate layer 3 is more preferably performed at 1050°C or lower, and even more preferably at 1000°C or lower. 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. The order of the intermediate layer smoothing step and the intermediate layer firing step can be reversed. The intermediate layer smoothing step can also be performed by lapping, leveling, cutting and polishing the surface, or the like.

[0077] (Electrolyte layer formation step) In the electrolyte layer formation step, the electrolyte layer 4 is formed as a thin layer on the protective layer 1b and the intermediate layer 3, covering the electrode layer 2 and the intermediate layer 3. The electrolyte layer 4 can be formed using any of the above-mentioned film-forming methods that can be used in low-temperature ranges, but spray coating is preferred. In particular, to form a high-quality electrolyte layer 4 that is dense, airtight, and has excellent gas barrier properties at temperatures of 1100°C or less, it is more preferred to use any of the aerosol deposition method, aerosol gas deposition method, powder jet deposition method, and particle jet deposition method. In this embodiment, the electrolyte layer 4 is formed using the aerosol deposition method. Specifically, aerosolized material powder for the electrolyte layer 4 (in this embodiment, a fine powder of stabilized zirconia such as YSZ or SSZ) is sprayed toward the protective layer 1b and the intermediate layer 3 on the metal support 1 to form the electrolyte layer 4.

[0078] (Reaction prevention layer formation step) In the reaction prevention layer forming step, the reaction prevention layer 5 is formed in a thin layer state 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 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.

[0079] (Counter electrode layer formation step) In the counter electrode layer formation step, the counter electrode layer 6 is formed in a thin layer state on the reaction prevention layer 5. The counter electrode layer 6 can be formed using the above-mentioned film formation method, but in order to suppress 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.

[0080] (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-generating cell of a solid oxide fuel cell. In other words, a solid oxide fuel cell in which a power-generating reaction occurs in the metal-supported electrochemical element E can be realized.

[0081] For example, a fuel gas containing hydrogen as a first gas is passed through the through-holes 1a from the rear surface of the metal support 1 to the counter electrode layer 6, and air as a second gas is passed through the electrode layer 2, and the temperature is maintained at a predetermined operating temperature (for example, 500°C to 900°C). In this case, when an electrolyte material that conducts oxygen ions is used for the electrolyte layer 4, oxygen O2 contained in the air is converted into electrons e - reacts with oxygen ions O 2- The oxygen ions O 2- The hydrogen H2 contained in the flowing fuel gas is converted into oxygen ions O2 in the counter electrode layer 6. 2- reacts with water H2O and electrons e - is generated.

[0082] When an electrolyte material that conducts hydrogen ions is used for the electrolyte layer 4, hydrogen H2 contained in the fuel gas flowing through the counter electrode layer 6 is converted into electrons e - releases hydrogen ions H +The hydrogen ions H + moves through the electrolyte layer 4 to the electrode layer 2. In the electrode layer 2, oxygen O2 and hydrogen ions H + , electronic e - reacts to produce water H2O.

[0083] The above reaction generates an electromotive force as an electrochemical output between the electrode layer 2 and the counter electrode layer 6. In this case, the counter electrode layer 6 functions as the fuel electrode (anode) of the fuel cell, and the electrode layer 2 functions as the air electrode (cathode).

[0084] Furthermore, a solid oxide fuel cell that can operate in a temperature range of 650°C or higher during rated operation is more preferable because it allows the construction of a fuel system that uses hydrocarbon gases such as city gas as raw fuel, in which the heat required to convert the raw fuel into hydrogen can be supplied by the exhaust heat of the fuel cell, thereby improving the power generation efficiency of the fuel cell system. Also, a solid oxide fuel cell that operates in a temperature range of 900°C or lower during rated operation is more preferable because it can enhance the effect of suppressing Cr volatilization from the metal-supported electrochemical element E, and a solid oxide fuel cell that operates in a temperature range of 850°C or lower during rated operation is even more preferable because it can further enhance the effect of suppressing Cr volatilization.

[0085] (Electrochemical Module) Next, the electrochemical module M will be described with reference to Fig. 2. The electrochemical module M includes a metal-supported electrochemical element E in a state where 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. The electrochemical module M is constructed by stacking (assembling) a plurality of these metal-supported electrochemical elements E with a current collecting member 26 sandwiched therebetween. In this embodiment, the current collecting member 26 is joined to the counter electrode layer 6 of the metal-supported electrochemical element E and the U-shaped member 9 to electrically connect them together, but the counter electrode layer 6 of the metal-supported electrochemical element E and the U-shaped member 9 may also be directly electrically connected together.

[0086] The electrochemical module M also has a gas manifold 17, a termination member, and a current draw-out section. One open end of the cylindrical support of the metal-supported electrochemical element E, which is stacked, is connected to the gas manifold 17, and the gas is supplied 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-holes 1a of the metal support 1.

[0087] (Electrochemical Devices and Energy Systems) Next, an electrochemical device Y and an energy system Z constructed using the electrochemical module M will be described with reference to FIG.

[0088] As shown in FIG. 3, the energy system Z has an electrochemical device Y and a heat exchanger 53 as a waste heat utilization unit that reuses heat circulated from the electrochemical device Y.

[0089] In this embodiment, the electrochemical device Y includes an electrochemical module M, a fuel converter 91 consisting of a desulfurizer 31 and a reformer 34, a fuel supply unit 46 that supplies fuel gas containing reducing components generated in the fuel converter 91 to the electrochemical module M, and an inverter 38, which is a type of power converter, as an output unit that extracts electric power from the electrochemical module M.

[0090] More specifically, the electrochemical device Y includes a desulfurizer 31, a reforming 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.

[0091] The desulfurizer 31 removes (desulfurizes) sulfur compounds contained in hydrocarbon raw fuel such as city gas. When sulfur compounds are contained in the raw fuel, the provision of the desulfurizer 31 can suppress the effects of the sulfur compounds on the reformer 34 or the metal-supported electrochemical element E. The vaporizer 33 generates steam from the reforming water supplied from the reforming water tank 32. The reformer 34 uses the steam generated in the vaporizer 33 to steam reform the raw fuel desulfurized in the desulfurizer 31, generating a reformed gas containing hydrogen.

[0092] The electrochemical module M generates electricity by electrochemical reaction using the reformed gas supplied from the reformer 34 and the air supplied from the blower 35. The combustion section 36 mixes the reaction exhaust gas discharged from the electrochemical module M with air and combusts combustible components in the reaction exhaust gas.

[0093] The electrochemical module M has 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 while electrically connected to each other, and one end (lower end) of each metal-supported electrochemical element E is fixed to the gas manifold 17. The metal-supported electrochemical element E generates electricity by causing an electrochemical reaction between the reformed gas supplied through the gas manifold 17 and air supplied from the blower 35.

[0094] The inverter 38 adjusts the output power of the electrochemical module M to the same voltage and frequency as the power received from a commercial grid (not shown). The control unit 39 controls the operation of the electrochemical device Y and the energy system Z.

[0095] The vaporizer 33, the reformer 34, the electrochemical module M, and the combustion section 36 are housed in a housing 40. The reformer 34 uses combustion heat generated by the combustion of the reaction exhaust gas in the combustion section 36 to carry out a reforming process of the raw fuel.

[0096] The raw fuel is supplied to the desulfurizer 31 through a raw fuel supply path 42 by operation of a booster pump 41. The reforming water in the reforming water tank 32 is supplied to the vaporizer 33 through a reforming water supply path 44 by operation of a reforming water pump 43. The raw fuel supply path 42 merges with the reforming water supply path 44 at a location downstream of the desulfurizer 31, and the reforming water and raw fuel that have merged outside the storage container 40 are supplied to the vaporizer 33 provided inside the storage container 40.

[0097] The reforming water is vaporized in the vaporizer 33 to become water vapor. The raw fuel containing water vapor produced in the vaporizer 33 is supplied to the reformer 34 through a water vapor-containing raw fuel supply path 45. The raw fuel is steam reformed in the reformer 34 to produce a reformed gas (first gas having a reducing component) 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 a fuel supply unit 46.

[0098] The reformed gas supplied to the gas manifold 17 is distributed to the plurality of metal-supported electrochemical elements E and supplied to the metal-supported electrochemical elements E from the lower end, which is the connection between the metal-supported electrochemical elements E and the gas manifold 17. Mainly hydrogen (reducing component) in the reformed gas is used in the electrochemical reaction in the metal-supported electrochemical elements E. The reaction exhaust gas, which contains 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.

[0099] The reaction exhaust gas is combusted in the combustion section 36 to become combustion exhaust gas, which is discharged to the outside of the storage container 40 through the combustion exhaust gas outlet 50. A combustion catalyst section 51 (e.g., a platinum-based catalyst) is arranged in the combustion exhaust gas outlet 50, and reduces the reducing components contained in the combustion exhaust gas, such as carbon monoxide and hydrogen, by combustion. The combustion exhaust gas discharged from the combustion exhaust gas outlet 50 is sent to a heat exchanger 53 through a combustion exhaust gas discharge path 52.

[0100] The heat exchanger 53 exchanges heat between the combustion exhaust gas generated by combustion in the combustion section 36 and the supplied cold water to generate hot water. That is, the heat exchanger 53 operates as a waste heat utilization section that reuses the heat discharged from the electrochemical device Y.

[0101] Instead of the exhaust heat utilization section, a reaction exhaust gas utilization section may be provided that utilizes the reaction exhaust gas discharged (without being combusted) from the electrochemical module M. The reaction exhaust gas contains the residual hydrogen gas that was not used in the reaction in the metal-supported electrochemical element E. In the reaction exhaust gas utilization section, the residual hydrogen gas is utilized to utilize heat through combustion or to generate electricity using a fuel cell or the like, thereby making effective use of energy.

[0102] Examples and Comparative Examples Examples and comparative examples will be described below.

[0103] [Items to be noted regarding item 2-03] [Formation of protective layer] As an example, a plurality of through holes 1a were formed by laser processing in a region with a radius of 2.5 mm from the center of a circular metal plate having a thickness of 0.3 mm and a diameter of 25 mm to produce a metal support 1. The diameter of the through holes 1a was approximately 25 μm at the opening on the front surface of the metal support 1 and approximately 50 μm inside.

[0104] Next, a protective layer 1b was formed on the entire surface of the metal support 1 by the above-mentioned electrodeposition coating method using Co--Mn as a protective material.

[0105] [Formation of electrode layer] Next, an electrode layer 2 was formed on the metal support 1, on whose entire surface a protective layer 1b had been formed. Specifically, LSCF-GDC was mixed, and an organic binder and an organic solvent (dispersion medium) were added to prepare a paste for forming the electrode layer (electrode layer preparation step). The mixing ratio of the organic solvent in the electrode layer paste was lower than in the protective layer paste, so that the viscosity of the paste for forming the electrode layer was adjusted to be higher than that of the protective layer paste.

[0106] Next, the electrode layer 2 was laminated in a region with a radius of 5 mm from the center of the metal support 1 using the prepared electrode layer forming paste (application step). The electrode layer 2 was formed by screen printing.

[0107] Thereafter, the metal support 1 on which the electrode layer 2 was laminated was subjected to a degreasing treatment at 450° C. in air (degreasing step).

[0108] Thereafter, the degreased metal support 1 was subjected to a firing treatment at a firing temperature of 900° C. in an air atmosphere for 1 hour (firing step).

[0109] [Formation of intermediate layer] After forming the electrode layer 2, the intermediate layer 3 was formed on the electrode layer 2. Specifically, first, an organic binder and an organic solvent (dispersion medium) were added to fine powder of GDC to prepare a paste. Using this paste, the intermediate layer 3 was laminated by screen printing in an area with a radius of 6 mm from the center of the metal support 1 on which the electrode layer 2 was formed. Then, the metal support 1 on which the intermediate layer 3 was laminated was compression molded and then fired to form an intermediate layer 3 with a flat surface (intermediate layer formation step, compression step).

[0110] Thereafter, an electrolyte layer forming step, a reaction prevention layer forming step, and a counter electrode layer forming step were carried out to manufacture a metal-supported electrochemical element E of the example.

[0111] A comparative metal-supported electrochemical element E was produced. In the production of the comparative example, the protective layer forming step was not performed, and the above-described electrode layer forming step, intermediate layer forming step, electrolyte layer forming step, reaction prevention layer forming step, and counter electrode layer forming step were performed on a metal support 1 on which no protective layer 1b was formed.

[0112] [Durability evaluation] Next, a durability test was conducted to evaluate the durability of the metal-supported electrochemical elements E according to the examples and comparative examples, based on whether the diffusion of Cr and the like from the metal support 1 to the electrode layer 2 and the like can be suppressed, and whether the generation of a high-resistance layer (particularly SrCrO4) can be suppressed.

[0113] The metal-supported electrochemical element E according to the present embodiment was prepared by coating a protective layer 1b on a metal support 1, firing the coated metal support 1 at the temperature, under the gas conditions, and for the firing time shown in Table 1 below, laminating an electrode layer 2 as an air electrode thereon, and firing the coated metal support 1 at the temperature, under the gas conditions, and for the firing time shown in Table 1 below. The metal-supported electrochemical element E according to the comparative example was prepared by laminating an electrode layer 2 as an air electrode on a metal support 1, and then firing the electrode layer 2 under the temperature, gas conditions, and firing time shown in Table 1 below. The durability conditions were a durability temperature (an example of a temperature range for use) of 950°C and a durability time (an example of a durability test period) of 100 hours. The specimen was left standing in an air atmosphere (gas conditions), and then removed and checked with a scanning electron microscope (JCM-7000) for the presence or absence of diffusion of Cr and other elements from the metal support 1 to the electrode layer 2, etc., and the presence or absence of a high-resistance layer (especially SrCrO4).

[0114] [Table 1]

[0115] FIG. 4 shows the current-voltage characteristics (IV characteristics) of the example and the comparative example. As shown in FIG. 4, the higher the current density, the higher the voltage of the example compared to the comparative example. As the current density increases, the electrochemical reaction becomes more active, reducing the concentration of the supplied material. However, in the comparative example, a high-resistance layer is formed due to the diffusion of Cr and other elements into the electrode layer 2, which is thought to further reduce the voltage. On the other hand, in the example, the provision of the protective layer 1b makes it possible to suppress the diffusion of elements such as Cr compared to the structure of the comparative example, which is thought to result in a higher voltage.

[0116] 5 to 7 show the results of EDX (Energy Dispersive X-ray Spectroscopy) of an electron microscope photograph of a cross section of metal-supported electrochemical element E according to an example after the durability test, and Figures 8 to 10 show the results of EDX (Energy Dispersive X-ray Spectroscopy) of an electron microscope photograph of a cross section of metal-supported electrochemical element E according to a comparative example after the durability test. EDX is an abbreviation for Energy Dispersive X-ray Spectroscopy, and is a technique for performing elemental analysis and composition analysis by detecting characteristic X-rays generated by electron beam irradiation and dispersing them by energy.

[0117] 5 to 10 show the EDX results of electron microscope photographs of the area corresponding to part A in FIG. 1, with FIGS. 5 and 8 showing the analysis results for the O element, FIGS. 6 and 9 showing the analysis results for the Cr element, and FIGS. 7 and 10 showing the analysis results for the Sr element, with areas with higher brightness indicating higher concentrations of the target elements. In the comparative examples shown in Figures 8 to 10, Cr (shown as Cr in Figure 9) diffuses into the electrode layer 2 serving as the air electrode, and a high-resistance layer (SrCrO4: shown as HI in the figure) is formed at the interface between the metal support 1 and the electrode layer 2. On the other hand, in the examples shown in Figures 5 to 7, the presence of the protective layer 1b suppresses the diffusion of Cr and the formation of the high-resistance layer. This result is consistent with the tendency of the IV characteristics shown in Figure 4. In elemental analysis, it was confirmed that 4.1 wt% of Cr was detected in the electrode layer 2 made of the LSCF of the comparative example, whereas no Cr was detected in the electrode layer 2 made of the LSCF of the example.

[0118] That is, the electrochemical element E according to the embodiment is subjected to a durability test in which it is exposed to an atmospheric atmosphere for a predetermined durability test period (for example, for a period of about 100 hours to 1000 hours) in the operating temperature range (a temperature range used as a solid oxide fuel cell or a solid oxide electrolysis cell, for example, a temperature range of about 500°C to 1000°C). After that, a cross section perpendicular to the front and back surfaces is analyzed by energy dispersive X-ray spectroscopy, and the analysis results show that Cr in the electrode layer 2 is below the detection standard (for example, in the EDX results for the Cr element, the brightness of the electrode layer 2 (including local portions) is below the brightness of the through hole 1a).

[0119] Furthermore, the electrochemical element E according to the embodiment is subjected to a durability test in which it is exposed to an atmospheric atmosphere for a predetermined durability test period (for example, for a period of approximately 100 hours to 1000 hours) in the operating temperature range (a temperature range used for solid oxide fuel cells or solid oxide electrolysis cells, for example, a temperature range of approximately 500°C to 1000°C). After that, a cross section perpendicular to the front and back surfaces is analyzed by energy dispersive X-ray spectroscopy. In the analysis results, high-resistance substances between the metal support 1 and the electrode layer 2 (for example, in the EDX results for the O element, the luminance near the interface between the metal support 1 and the protective layer 1b is less than the luminance of the metal support 1, and in the EDX results for the Cr element, the luminance near the interface between the metal support 1 and the protective layer 1b is less than the luminance of the metal support 1, and in the EDX results for the Sr element, the luminance near the interface between the metal support 1 and the protective layer 1b is less than the luminance of the metal support 1) are below the detection standard.

[0120] [Another embodiment] [1] In the above embodiment, the protective layer 1b is formed on the entire surface of the metal support 1, but the present invention is not limited to this. It is sufficient that the protective layer 1b is formed at least on the back surface of the metal support 1 opposite to the surface on which the electrode layer 2 is provided, and on the inner wall of the through hole 1a. In other words, the protective layer 1b may be formed on the inner wall of the through hole 1a in the metal support 1.

[0121] [2] In the above embodiment, the firing step is performed in the electrode layer formation step, and the protective layer 1b and the electrode layer 2 are formed by a single firing process. However, the present invention is not limited to this. For example, the protective layer 1b may be laminated on the metal support 1 in the protective layer formation step, and then the firing step may be performed to form the protective layer 1b, and then the electrode layer formation step may be performed.

[0122] [3] In the above embodiment, an intermediate layer forming step and a reaction prevention layer forming step are performed when manufacturing the metal-supported electrochemical element E, and the metal-supported electrochemical element E is provided with the intermediate layer 3 and the reaction prevention layer 5. However, the present invention is not limited to this, and the metal-supported electrochemical element E may be provided without the intermediate layer 3 or the reaction prevention layer 5. In an embodiment without the intermediate layer 3, the electrolyte layer 4 is formed on the electrode layer 2, and in an embodiment without the reaction prevention layer 5, the counter electrode layer 6 is formed on the electrolyte layer 4.

[0123] [4] In the above embodiment, the metal-supported electrochemical element E is used in a solid oxide fuel cell. However, the metal-supported electrochemical element E can also be used in a solid oxide electrolysis cell, an oxygen sensor using a solid oxide, or the like. When the metal-supported electrochemical element E is operated as an electrolysis cell, a gas containing water vapor and carbon dioxide is passed through the counter electrode layer 6, and a voltage is applied between the electrode layer 2 and the counter electrode layer 6. Then, electrons e - reacts with water H2O and carbon dioxide molecules CO2, producing hydrogen H2, carbon monoxide CO, and oxygen ions O 2- Oxygen ions O 2- The oxygen ions O migrate through the electrolyte layer 4 to the electrode layer 2. Then, the oxygen ions O migrate to the electrode layer 2 (an example of an oxygen evolving electrode). 2- releases electrons and becomes oxygen O2. Through the above reaction, water H2O is electrolyzed into hydrogen H2 and oxygen O2. When gas containing carbon dioxide molecules CO2 is circulated, it is electrolyzed into carbon monoxide CO and oxygen O2. 11 shows an example of an electrochemical device Y1 and an energy system Z1 when the metal-supported electrochemical element E is operated as an electrolytic cell that generates gas through the above-mentioned electrolytic reaction. As shown in the figure, the energy system Z1 has the electrochemical device Y1 and two heat exchangers 90 and 92 as exhaust heat utilization units that reuse heat circulated from the electrochemical device Y1. In this embodiment, the electrochemical device Y1 has an electrochemical module M, a fuel converter 91 that synthesizes hydrocarbons based on hydrogen and other fuels 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, 171. The plurality of metal-supported electrochemical elements E are arranged in parallel and electrically connected to each other. One end (lower end) of each 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 a supply of water vapor and carbon dioxide. Hydrogen, carbon monoxide, and the like produced by the above-mentioned reactions in the metal-supported electrochemical element E are collected by the gas manifold 171, which communicates with the other end. In addition, in this embodiment, the heat exchanger 90 operates as a waste heat utilization unit that exchanges heat between the reaction heat generated by the reaction in the fuel converter 91 and water to vaporize the water, and the heat exchanger 92 operates 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 the water, thereby improving energy efficiency. Furthermore, the power converter 93 supplies electric power to the metal-supported electrochemical element E of the electrochemical module M. This allows the metal-supported electrochemical element E to function as an electrolysis cell. Therefore, with the above configuration, it is possible to realize an electrochemical device Y1 and an energy system Z1 that can improve the efficiency of converting electrical energy into chemical energy such as fuel.

[0124] [5] In the above embodiment, a plurality of metal-supported electrochemical elements E are used in combination as the electrochemical module M, but this is not limiting and each element may be used alone.

[0125] [6] In the above embodiment, the energy system Z, Z1 is provided with a waste heat utilization unit that reuses the heat discharged from the electrochemical device Y, Y1, but this is not limited to this and the energy system Z, Z1 may be provided with no waste heat utilization unit.

[0126] [7] In the above embodiment, the electrochemical module M includes a metal-supported electrochemical element E in which a cylindrical support is formed by the metal support 1 and the U-shaped member 9 attached to the rear surface of the metal support 1. However, the present invention is not limited to this. For example, as shown in Fig. 12, the electrochemical module M may be configured by stacking metal-supported electrochemical elements E with inter-cell connection members 71 sandwiched therebetween. In this case, the inter-cell connection member 71 is a plate-like member that is conductive and gas impermeable, and has grooves 72 formed on the front and back surfaces that are perpendicular to each other. The inter-cell connection member 71 can be made of a metal such as stainless steel or a metal oxide. When metal-supported electrochemical elements E are stacked with this inter-cell connecting member 71 sandwiched therebetween, gas can be supplied to the metal-supported electrochemical elements E through the grooves 72. More specifically, the grooves 72 formed on one surface serve as first gas flow paths 72a, which supply gas to the front side of the metal-supported electrochemical element E, i.e., to the counter electrode layer 6. The grooves 72 formed on the other surface serve as second gas flow paths 72b, which supply gas to the back side of the metal-supported electrochemical element E, i.e., from the back surface of the metal support 1, through the through-holes 1a to the electrode layer 2. When the electrochemical module M configured in this manner is operated as a power generation cell of a solid oxide fuel cell, air is supplied to the first gas flow path 72a and hydrogen is supplied to the second gas flow path 72b. This causes a power generation reaction to proceed in the metal-supported electrochemical elements E, generating electromotive force and current. The generated power is extracted from the electrochemical module M through the inter-cell connection members 71 at both ends of the stacked metal-supported electrochemical elements E. The grooves 72 formed on the front surface and the rear surface of the inter-cell connection member 71 may be parallel to each other.

[0127] [8] In the above embodiment, the metal-supported electrochemical element E is mainly used in flat-plate or cylindrical-plate solid oxide fuel cells, but this is not limited thereto and it can also be used in elements such as cylindrical solid oxide fuel cells.

[0128] [9] In the above embodiment, the electrochemical device Y includes an electrochemical module M having a plurality of metal-supported electrochemical elements E, but this is not limiting. For example, the electrochemical device may include a single metal-supported electrochemical element E.

[0129] [Items to be noted regarding consideration item 03]

[10] In the above embodiment, the electrolyte layer 4 is in direct contact with (laminated on) the protective layer 1b of the metal support 1. Alternatively, although not shown, the electrolyte layer 4 may be laminated on the protective layer 1b of the metal support 1 without contacting the protective layer 1b, with the electrode layer 2 and intermediate layer 3 interposed therebetween.

[0130] Furthermore, the configurations disclosed in the above embodiments (including other embodiments, the same applies below) can be applied in combination with configurations disclosed in other embodiments, as long as no contradictions arise. Furthermore, the embodiments disclosed in this specification are examples, and the embodiments of the present invention are not limited to these, and can be modified as appropriate within the scope that does not deviate from the purpose of the present invention. [Explanation of symbols]

[0131] 1: Metal support 1a: Through hole 1b: Protective layer 2: Electrode layer 3: Middle class 4: Electrolyte layer 6: Counter electrode layer 31: Desulfurizer (fuel converter) 34: Reformer (fuel converter) 38: Inverter (power converter) 53: Heat exchanger (exhaust heat utilization section) 90, 92: Heat exchanger (exhaust heat utilization section) 91: Fuel converter 93: Power converter E: Metal-supported electrochemical element (electrochemical element) M: Electrochemical module Y, Y1: Electrochemical device Z, Z1: Energy system

Claims

1. A method for producing an electrochemical device in which an electrode layer is formed on a metal support having through-holes, comprising the steps of: a protective layer forming step of forming a protective layer on one of the front and rear surfaces of the metal support, on which the electrode layer is to be provided, so that a space opening to the front and rear surfaces of the metal support is formed in the through hole; an electrode layer forming step of forming the electrode layer on the metal support after the protective layer forming step, the electrode layer serves as an air electrode when a power generation reaction occurs, and serves as an oxygen evolution electrode when an electrolysis reaction occurs; In the protective layer forming step, Co—Mn, Cu—Mn, Ni—Co—Mn, Ni—Mn, Zn—Co, Zn—Co—Mn, Co ３ O ４ , Co, Ni—Co, Co—Mn, and Ni—Co—Mn as a protective material to form the protective layer.

2. The method for manufacturing an electrochemical device according to claim 1 , wherein in the protective layer forming step, the protective layer is formed on the entire surface of the metal support.

3. In the protective layer forming step, Co—Mn, Cu—Mn, Ni—Co—Mn, Ni—Mn, Zn—Co, Zn—Co—Mn, Co ３ O ４ and forming the protective layer by a plating coating method using at least one of Co, Ni—Co, Co—Mn, and Ni—Co—Mn as the protective material.

4. a metal support having a through hole; an electrode layer disposed on the metal support; a protective layer formed on one of the front and rear surfaces of the metal support on which the electrode layer is to be provided, a space that is open to the front and back surfaces of the metal support is formed in the through hole, the electrode layer serves as an air electrode when a power generation reaction occurs, and serves as an oxygen evolution electrode when an electrolysis reaction occurs; The protective layer may be made of Co—Mn, Cu—Mn, Ni—Co—Mn, Ni—Mn, Zn—Co, Zn—Co—Mn, Co ３ O ４ , Co, Ni--Co, Co--Mn, and Ni--Co--Mn as protective materials.

5. 5. The electrochemical device according to claim 4, wherein the protective layer is formed on the entire surface of the metal support.

6. an electrolyte layer disposed on the electrode layer; 6. The electrochemical device according to claim 4, further comprising: a counter electrode layer disposed on the electrolyte layer.

7. 7. The electrochemical device according to claim 6, further comprising an intermediate layer disposed between the electrode layer and the electrolyte layer.

8. 6. The electrochemical element according to claim 4, wherein a cross section perpendicular to the front and back surfaces of the electrochemical element is analyzed by energy dispersive X-ray spectroscopy after a durability test in which the electrochemical element is exposed to an air atmosphere in an operating temperature range for a predetermined durability test period, and the result shows that Cr in the electrode layer is below the detection limit.

9. 6. The electrochemical element according to claim 4 or 5, wherein a cross section perpendicular to the front and back surfaces of the electrochemical element is analyzed by energy dispersive X-ray spectroscopy after a durability test in which the electrochemical element is exposed to an air atmosphere in an operating temperature range for a predetermined durability test period, and the analysis results show that a high-resistance substance between the metal support and the electrode layer is below a detection standard.

10. An electrochemical module comprising a plurality of electrochemical elements according to claim 4 arranged in a group.

11. A solid oxide fuel cell comprising the electrochemical element according to claim 4, wherein a power generation reaction occurs in the electrochemical element.

12. A solid oxide electrolysis cell comprising the electrochemical element according to claim 4, wherein an electrolytic reaction occurs in the electrochemical element.

13. The electrochemical element according to claim 4 or the electrochemical module according to claim 10; a fuel converter that generates a reducing component to be supplied to the electrochemical element or the electrochemical module, or that converts a gas containing a reducing component generated in the electrochemical element or the electrochemical module.

14. The electrochemical element according to claim 4 or the electrochemical module according to claim 10; an electric power converter that extracts electric power from the electrochemical element or the electrochemical module, or that distributes electric power to the electrochemical element or the electrochemical module.

15. The electrochemical device according to claim 13; and a waste heat utilization unit that reuses heat discharged from the electrochemical device.

16. The electrochemical device according to claim 13; and a waste heat utilization unit that reuses heat discharged from the electrochemical device.

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