JP2023148149A - Electrode layer formation method, electrode layer, electrochemical element, electrochemical module, solid oxide fuel cell, solid oxide electrolytic cell, electrochemical device, and energy system - Google Patents

Abstract

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

Description

The present invention relates to a method for forming an electrode layer, an electrode layer, and an electrochemical element, an electrochemical module, a solid oxide fuel cell, a solid oxide electrolytic cell, an electrochemical device, and an energy system including the electrode layer.

In conventional electrolyte-supported solid oxide fuel cells (SOFCs) and electrode-supported SOFCs, in order to obtain sufficient interlayer adhesion strength and high-quality electrode and electrolyte layers, high temperatures (for example, around 1400°C) are required. is fired.

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

When manufacturing a metal-supported SOFC, if heat treatment is performed at a high temperature (for example, about 1400°C), a thick metal oxide film containing Cr etc. will be formed on the surface of the metal support, making it easy to crack or peel off. Diffusion of elements such as Cr from the metal support may affect the constituent elements (electrode layer, electrolyte layer) of the SOFC, resulting in a decrease in the performance and durability of the SOFC.

Therefore, for example, a method described in Patent Document 1 has been proposed as a method for manufacturing a metal-supported SOFC.

The method described in Patent Document 1 includes a step of pre-calcining an unfired fuel electrode layer under non-reducing conditions at a temperature of 950 to 1100° C. for 15 to 60 minutes, and a step of pre-calcining the unfired fuel electrode layer under a reducing atmosphere using a gaseous reducing agent such as hydrogen. In this method, the fuel electrode layer is formed by performing a step of firing at a temperature of 950 to 1100° C. for 15 to 60 minutes.

Patent No. 6794505

However, in the method described in Patent Document 1, it is necessary to perform firing at a high temperature of 950 to 1100° C. while supplying a gas containing hydrogen. Therefore, in order to properly process the gas, explosion-proof equipment is required, which poses a problem of requiring a large amount of equipment cost.

The present invention was made in view of the above circumstances, and provides an electrode layer forming method, an electrode layer, and an electrochemical element equipped with an electrode layer that does not require the supply of hydrogen during firing and can reduce equipment costs required for manufacturing. , an electrochemical module, a solid oxide fuel cell, a solid oxide electrolytic cell, an electrochemical device, and an energy system.

The characteristic structure of the electrode layer forming method according to the present invention for achieving the above object is as follows:
A method of forming an electrode layer on a metal support, the method comprising:
an electrode layer lamination step of laminating an electrode layer on the metal support;
a firing step of firing the electrode layer laminated on the metal support,
The firing step is performed in an atmosphere in which the partial pressure of oxygen is 4.0×10 ⁻⁸ bar or more and 4.0×10 ⁻⁶ bar or less.

As a result of extensive research, the inventor of the present application has found that when forming an electrode layer on a metal support, an oxygen partial pressure of 4.0×10 ⁻⁸ bar or more that can be achieved without supplying hydrogen is 4.0× It was discovered that a high quality electrode layer with high adhesion strength to the metal support could be formed by firing in an atmosphere of 10 ⁻⁶ bar or less, leading to the completion of the present invention.

That is, according to the above characteristic structure, it is possible to form a high-quality electrode layer on the metal support with high adhesion strength to the metal support. Further, there is no need to supply hydrogen during firing, and the cost of equipment required for manufacturing can be reduced.

Further characteristic configurations of the electrode layer forming method of the present invention are:
The firing step is performed under an inert gas atmosphere having a dew point of 10° C. or more and 70° C. or less.

According to the characteristic configuration described above, an atmosphere with an oxygen partial pressure of 4.0×10 ⁻⁸ bar to 4.0×10 ⁻⁶ bar can be achieved using only humidified inert gas without supplying hydrogen.

Further characteristic configurations of the electrode layer forming method of the present invention are:
The inert gas is nitrogen.

Nitrogen is relatively inexpensive and does not require special equipment to handle. Therefore, according to the characteristic configuration described above, the cost required for forming the electrode layer can be suppressed.

Further characteristic configurations of the electrode layer forming method of the present invention are:
The firing step is performed at a temperature of 800°C or more and 1100°C or less.

If the firing temperature is too low, a good quality electrode layer may not be formed, while if the firing temperature is too high, the metal support may be damaged. However, according to the above characteristic structure, a high quality electrode layer can be formed and damage to the metal support can be suppressed.

Further characteristic configurations of the electrode layer forming method of the present invention are:
Before performing the firing step, a degreasing step for removing oil is performed.

According to the above-described characteristic configuration, it is possible to suppress defects in film formation of the electrode layer due to dirt such as oil and fat, and to ensure good quality of the electrochemical element and the like.

Further characteristic configurations of the electrode layer forming method of the present invention are:
The degreasing step is performed at a temperature of 150°C or more and 650°C or less.

If the temperature during degreasing is too low, there is a risk that dirt such as oil and fat will not be removed sufficiently, while if the temperature during degreasing is too high, the metal support may be damaged or a high-quality electrode layer may not be formed. There is. However, according to the above characteristic structure, it is possible to appropriately remove stains such as oil and fat, and also to suppress damage to the metal support, thereby forming a high-quality electrode layer.

The characteristic structure of the electrode layer according to the present invention is as follows:
It is formed on a metal support and has a tensile strength of 1.2 MN/m ² or more.

According to the above characteristic structure, the adhesion strength with the metal support is high, and the electrochemical element and the like equipped with the same have excellent strength (reliability), durability, and performance.

Further characteristic configurations of the electrode layer according to the present invention are:
It consists of at least one selected from nickel-based compounds, ceria-based oxides, zirconia-based oxides, and perovskite-based composite oxides, or a combination thereof.

According to the above characteristic configuration, a nanocomposite structure is formed and has sufficient electrode performance.

Further characteristic configurations of the electrode layer according to the present invention are:
The point is that the porosity is 5% or more.

According to the characteristic configuration described above, a three-dimensional gas diffusion path is formed, and the electrode performance can be improved.

Further characteristic configurations of the electrode layer according to the present invention are:
It is formed on the diffusion prevention layer formed on the metal support.

According to the above characteristic configuration, it is possible to suppress the diffusion of Cr and the like from the metal support containing Cr to the electrode layer.

Further characteristic configurations of the electrode layer according to the present invention are:
The thickness of the diffusion prevention layer is 3 μm or less.

If the diffusion prevention layer is too thick, the electrical resistance may become too high. However, according to the above-mentioned characteristic configuration, it is possible to achieve both suppression of diffusion of Cr and the like and low electrical resistance.

The characteristic configuration of the electrochemical device according to the present invention is as follows:
the electrode layer;
an electrolyte layer disposed on the electrode layer;
and a counter electrode layer disposed on the electrolyte layer.

According to the above characteristic structure, the adhesion strength between the metal support and the electrode layer is high, and the electrochemical element has excellent strength (reliability), durability, and performance.

Further characteristic configurations of the electrochemical device according to the present invention are:
The present invention has an intermediate layer between the electrode layer and the electrolyte layer.

According to the above characteristic configuration, the reaction between the constituent materials of the electrode layer and the constituent materials of the electrolyte layer can be effectively suppressed, and the long-term stability of the performance of the electrochemical element can be improved.

The characteristic configuration of the electrochemical module according to the present invention is as follows:
The point is that a plurality of the electrochemical elements are arranged in a group.

According to the above characteristic configuration, by arranging multiple electrochemical elements in a group, a compact, high-performance electrochemical module with excellent strength and reliability is realized while suppressing material and processing costs. can. For example, when the electrochemical module is operated as a fuel cell, it is also possible to obtain a large power generation output.

The characteristic structure of the solid oxide fuel cell according to the present invention is as follows:
The present invention includes the electrochemical element described above, and causes a power generation reaction to occur in the electrochemical element.

According to the above characteristic configuration, power generation reactions can be performed as a solid oxide fuel cell equipped with an electrochemical element with excellent strength (reliability), durability, and performance. A high-performance solid oxide fuel cell can be obtained.

The characteristic configuration of the solid oxide electrolytic cell according to the present invention is as follows:
The present invention includes the electrochemical element described above, and causes an electrolytic reaction to occur in the electrochemical element.

According to the above characteristic configuration, gas can be generated by electrolytic reaction as a solid oxide electrolytic cell equipped with an electrochemical element with excellent strength (reliability), durability, and performance, so that gas can be generated with high reliability and A solid oxide electrolytic cell with high durability and high performance can be obtained.

The characteristic configuration of the electrochemical device according to the present invention is as follows:
The electrochemical element or the electrochemical module;
a fuel converter that generates a reducing component to be supplied to the electrochemical element or the electrochemical module, or converts a gas containing a reducing component that is generated in the electrochemical element or the electrochemical module; It is in the point of having.

According to the above characteristic configuration, when an electrochemical element or an electrochemical module is operated as a fuel cell, a reformer, etc. It is possible to realize an electrochemical device including an electrochemical element or an electrochemical module that can be configured to generate hydrogen using a fuel converter and has excellent durability, reliability, and performance. Furthermore, since it becomes easier to construct a system for recycling unused fuel gas distributed from the electrochemical module, a highly efficient electrochemical device can be realized.
On the other hand, when an electrochemical element or an electrochemical module is operated as an electrolytic cell, a gas containing water vapor or carbon dioxide is passed through the electrode layer, and a voltage is applied between the electrode layer and the counter electrode layer. Then, in the electrode layer, the electron e ^- reacts with water H ₂ O and carbon dioxide molecule CO ₂ to form hydrogen H ₂ , carbon monoxide CO, and oxygen ion O ^{2 -} . The generated oxygen ions O ^2- move to the counter electrode layer through the electrolyte layer. Then, in the counter electrode layer, the oxygen ions O ^2- release electrons and become oxygen O ₂ . As a result of the above reaction, when a gas containing water vapor flows, water _H2O is decomposed into hydrogen _H2 and oxygen _O2 , and when a 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 distributed, various compounds such as hydrocarbons are extracted from the hydrogen and carbon monoxide generated in the electrochemical element or electrochemical module by the electrolysis. A synthetic fuel converter can be provided. This allows the hydrocarbons and the like generated by the fuel converter to flow to the electrochemical element or the electrochemical module, or to be taken out of the system/apparatus and used separately as fuel or chemical raw materials.

The characteristic configuration of the electrochemical device according to the present invention is as follows:
The electrochemical element or the electrochemical module;
The present invention includes at least a power converter that extracts electric power from the electrochemical element or the electrochemical module, or distributes electric power to the electrochemical element or the electrochemical module.

According to the above characteristic configuration, the power converter can take out the electric power generated by the electrochemical element or the electrochemical module, or can distribute the electric power to the electrochemical element or the electrochemical module. Thereby, as described above, the electrochemical element or electrochemical module acts as a fuel cell or as an electrolytic cell. Therefore, according to the characteristic structure described above, it is possible to realize an electrochemical device 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 using an inverter as a power converter, when operating as a fuel cell, the inverter can boost the voltage or convert direct current to alternating current. This is preferable because it makes it easier to use the electrical output. Further, when operating as an electrolytic cell, it is preferable because an electrochemical device can be constructed that can obtain direct current from an alternating current power source and supply direct current power to an electrochemical element or an electrochemical module.

The characteristic configuration of the energy system according to the present invention is as follows:
The above electrochemical device,
The present invention includes at least an exhaust heat utilization section that reuses heat discharged from the electrochemical device.

According to the above characteristic configuration, it is possible to realize an energy system that is excellent in durability, reliability, performance, and energy efficiency. It is also possible to realize a hybrid system with excellent energy efficiency by combining it with a power generation system that generates electricity using the combustion heat of unused fuel gas discharged from the electrochemical device.

FIG. 1 is a diagram showing a schematic configuration of a metal-supported electrochemical device according to an embodiment. FIG. 1 is a diagram showing a schematic configuration of an electrochemical module according to an embodiment. 1 is a diagram showing a schematic configuration of an electrochemical device and an energy system according to an embodiment. This is an image obtained by photographing the metal support of Example 4 after a peel test. This is an image obtained by photographing the metal support of Example 6 after a peel test. This is an image obtained by photographing the metal support of Comparative Example 2 after the peel test. FIG. 2 is a diagram showing a schematic configuration of an electrochemical device and an energy system according to another embodiment. FIG. 3 is a diagram showing a schematic configuration of an electrochemical module according to another embodiment.

Hereinafter, an electrode layer 2 according to an embodiment, a method for forming the electrode layer 2, a metal-supported electrochemical element E provided with the electrode layer 2, a method for manufacturing the metal-supported electrochemical element E, and a solid oxide fuel cell (Solid oxide fuel cell) will be described below. Oxide Fuel Cell (SOFC), electrochemical module M, electrochemical device Y, and energy system Z will be explained. In this embodiment, the metal-supported electrochemical element E is used as a component of a solid oxide fuel cell that generates electricity by receiving a fuel gas containing hydrogen and air (oxidant gas). In the following, when expressing the positional relationship of layers, for example, the side of the counter electrode layer 6 viewed from the electrolyte layer 4 will be referred to as "upper" or "upper side", and the side of the electrode layer 2 will be referred to as "lower" or "lower side". There are cases. Further, 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 surface on the opposite side may be referred to as the "back surface".

(electrochemical device)
As shown in FIG. 1, the metal-supported electrochemical device E includes a metal support 1, an electrode layer 2, an intermediate layer 3 formed on the electrode layer 2, and a metal support 1, an electrode layer 2, an intermediate layer 3 formed on the electrode layer 2, and It is a metal-supported electrochemical element having an electrolyte layer 4, a reaction prevention layer 5 formed on the electrolyte layer 4, and a counter electrode layer 6 formed on the reaction prevention layer 5. That is, 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.

(metal support)
The metal support 1 supports the electrode layer 2, intermediate layer 3, electrolyte layer 4, reaction prevention layer 5, and counter electrode layer 6 to maintain the strength of the metal support type electrochemical element E. That is, the metal support 1 plays a role as a support that supports the components of the electrochemical element.

As the material for the metal support 1, a material with excellent electronic conductivity, heat resistance, oxidation resistance, and corrosion resistance is used. For example, ferritic stainless steel, austenitic stainless steel, nickel-based alloy, etc. are used. In particular, alloys containing chromium are preferably used. In this embodiment, the metal support 1 uses an Fe-Cr alloy containing 18% by mass or more and 25% by mass or less of Cr, but an Fe-Cr alloy containing 0.05% by mass or more of Mn, Fe-Cr alloy containing 0.15% by mass or more and 1.0% by mass or less of Ti, Fe-Cr alloy containing 0.15% by mass or more and 1.0% by mass or less of Zr, and containing Ti and Zr. Fe-Cr alloy with a total content of Ti and Zr of 0.15% by mass or more and 1.0% by mass or less, Fe-Cr alloy containing Cu of 0.10% by mass or more and 1.0% by mass or less Alloys are particularly preferred.
It is preferable that the metal support 1 is made of a ferritic stainless steel material, since this makes it possible to realize a metal-supported electrochemical element that is inexpensive and has high strength.

The metal support 1 has a plate shape as a whole. The metal support 1 only needs to have sufficient strength to form the metal supported electrochemical element E as a support, and its thickness may be, for example, 0.1 mm or more in order to ensure the strength. It is preferably at least 0.15 mm, more preferably at least 0.2 mm, and even more preferably at least 0.2 mm. Further, from the viewpoint of reducing costs, the thickness thereof is, for example, preferably 2 mm or less, more preferably 1 mm or less, and even more preferably 0.5 mm or less. The metal support 1 has a plurality of through holes 1a that penetrate from the surface where the electrode layer 2 is provided (the front surface) to the back surface. In this embodiment, the metal support 1 is formed by mechanical, chemical, or optical perforation processing, such as punching, etching, or laser processing, so as to penetrate the front and back surfaces of the metal plate. This is a metal plate with a plurality of through holes 1a formed by hole machining or the like. Thereby, fuel gas and air can be smoothly supplied from the back side of the metal support 1 to the electrode layer 2 side, so that a high performance metal support type electrochemical element can be realized.
Note that it is also possible to use the plate-shaped metal support 1 by bending it and deforming it into, for example, a box shape or a cylindrical shape.

A metal oxide layer 1b is provided on the surface of the metal support 1 as a diffusion prevention layer. That is, a diffusion prevention layer is formed between the metal support 1 and the electrode layer 2, which will be described later. The metal oxide layer 1b is provided not only on the surface exposed to the outside of the metal support 1 but also on the contact surface (interface) with the electrode layer 2 and the inner surface of the through hole 1a. This metal oxide layer 1b can suppress elemental interdiffusion between the metal support 1 and the electrode layer 2. For example, when ferritic stainless steel containing chromium is used as the metal support 1, the metal oxide layer 1b mainly consists of chromium oxide. Further, the metal oxide layer 1b containing chromium oxide as a main component suppresses diffusion of chromium atoms and the like of the metal support 1 into the electrode layer 2 and the electrolyte layer 4. The thickness of the metal oxide layer 1b may be any thickness that can achieve both high diffusion prevention performance and low electrical resistance, and the maximum thickness is preferably 3 μm or less. Note that it is more preferable that the thickness is on the submicron order, and specifically, it is more preferable that the average thickness is about 0.3 μm or more and 0.7 μm or less. Moreover, it is more preferable that the minimum thickness is about 0.1 μm or more. Further, it is preferable that the maximum thickness is about 1.1 μm or less.

Although the metal oxide layer 1b can be formed by various methods, a method in which the surface of the metal support 1 is oxidized to form a metal oxide is preferably used. Further, the metal oxide layer 1b may be formed on the surface of the metal support 1 by a sputtering method, a PVD method such as a PLD method, a CVD method, a spray coating method (a thermal spray method, an aerosol deposition method, an aerosol gas deposition method, a powder jet deposition method, etc.). It may be formed by a method such as a position method, a particle jet deposition method, or a cold spray method, or it may be formed by plating and oxidation treatment. Further, the metal oxide layer 1b may include a highly conductive spinel phase.

(electrode layer)
As shown in FIG. 1, the electrode layer 2 can be provided in a thin layer on the surface of the metal support 1 so as to cover the region of the metal support 1 in which the through hole 1a is formed. When forming a thin layer, the thickness can be, for example, about 1 μm to 100 μm, preferably 5 μm to 50 μm. With such a thickness, sufficient electrode performance can be ensured while reducing the amount of expensive electrode layer material used and reducing costs. Further, the entire region of the metal support 1 where the through hole 1a is provided is covered with the electrode layer 2. That is, the through hole 1a is formed inside the region of the metal support 1 where the electrode layer 2 is formed. In other words, all the through holes 1a are provided facing the electrode layer 2.

As the material for the electrode layer 2, at least one selected from nickel-based compounds, ceria-based oxides, zirconia-based oxides, and perovskite-based composite oxides, or a combination of these can be used. For example, composite materials such as NiO-GDC, Ni-GDC, NiO-YSZ, Ni-YSZ, CuO-CeO ₂ , Cu-CeO ₂ can be used. In these examples, GDC, YSZ, _CeO2 can be referred to as composite aggregates. The electrode layer 2 constructed using the above materials functions as an anode. By using these materials, a nanocomposite structure is formed, and the electrode layer 2 has sufficient electrode performance.

The electrode layer 2 can be formed using a low-temperature firing method (for example, a wet method using a firing treatment in a low temperature range without firing treatment in a high temperature range higher than 1100°C), a spray coating method (a thermal spraying method, an aerosol deposition method, or an aerosol gas method). It is preferable to form by a method such as a deposition method, a powder jet deposition method, a particle jet deposition method, or a cold spray method), a PVD method (such as a sputtering method or a pulse laser deposition method), or a CVD method. By using these processes that can be used in a low temperature range, a good electrode layer 2 can be obtained without using firing in a high temperature range higher than 1100° C., for example. Therefore, it is possible to suppress element diffusion between the metal support 1 and the electrode layer 2 without damaging the metal support 1, and to realize a metal support type electrochemical element with excellent durability, which is preferable. Furthermore, it is even more preferable to use a low-temperature firing method because the raw materials can be easily handled.

In this embodiment, the electrode layer 2 is formed through a firing step described below in an atmosphere where the partial pressure of oxygen is 4.0×10 ⁻⁸ bar or more and 4.0×10 ⁻⁶ bar or less. The tensile strength is 1.2 MN/m ² or more, and the adhesiveness with the metal support 1 is excellent, and the adhesiveness with the intermediate layer 3 is also good. Therefore, metal-supported electrochemical elements have excellent strength (reliability), durability, and performance.

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% or more and 60% or less. Moreover, the electrode layer 2 is formed so that its density is greater than 40% and less than 95%, for example. The size of the pores can be appropriately selected so that the electrochemical reaction proceeds smoothly. Note that the density is the ratio of the material constituting the layer to the space, and can be expressed as (1-porosity), and is equivalent to the relative density.

(middle class)
The intermediate layer 3 can be formed as a thin layer on the electrode layer 2, covering the electrode layer 2, as shown in FIG. In this way, in order to form a dense electrolyte layer 4 on top of the porous electrode layer 2, the intermediate layer 3 continuously connects the two and is used during manufacturing and operation of the metal-supported electrochemical element E. It is placed between the two as a layer that has a buffering effect that relieves various stresses that are applied at times. Therefore, the intermediate layer 3 is intentionally formed to have a smaller density than the electrolyte layer 4. Furthermore, the intermediate layer 3 is intentionally formed to have a higher density than the electrode layer 2. As a result, even when a porous electrode layer 2 and a dense electrolyte layer 4 are formed on the metal support 1, the intermediate layer 3 absorbs and relieves various stresses between each layer, and the metal It also has the effect of improving the performance, reliability, and stability of the supported electrochemical element E. When forming a thin layer, the thickness can be, for example, about 1 μm to 100 μm, preferably about 2 μm to 50 μm, more preferably about 4 μm to 25 μm. With such a thickness, sufficient performance can be ensured while reducing the amount of expensive intermediate layer material used and reducing costs.

Examples of the material 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) etc. can be used. In particular, ceria-based ceramics are preferably used.

The intermediate layer 3 can be formed by a low-temperature firing method (for example, a wet method using a firing process in a low-temperature range without firing in a high-temperature range higher than 1100°C) or a spray coating method (thermal spraying method, aerosol deposition method, or aerosol gas deposition method). It is preferable to form by a method such as a powder jet deposition method, a powder jet deposition method, a particle jet deposition method, a cold spray method, etc.), a PVD method (sputtering method, a pulsed laser deposition method, etc.), a CVD method, or the like. By using these film forming processes that can be used in a low temperature range, the intermediate layer 3 can be obtained without using baking in a high temperature range higher than 1100° C., for example. Therefore, mutual diffusion of elements between the metal support 1 and the electrode layer 2 can be suppressed without damaging the metal support 1, and a metal support type electrochemical element E with excellent durability can be realized. Further, it is more preferable to use a low-temperature firing method because the raw materials can be easily handled.

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. The intermediate layer 3 having such properties is suitable for application to the metal-supported electrochemical element E.

(electrolyte layer)
The electrolyte layer 4 is formed in a thin layer on the intermediate layer 3, as shown in FIG. Further, it can also be formed in the form of a thin film with a thickness of 10 μm or less. In this embodiment, the electrolyte layer 4 is provided over (astride) the intermediate layer 3 and the metal support 1 . By configuring in this manner and bonding the electrolyte layer 4 to the metal support 1, the metal support type electrochemical element E can be made to have excellent robustness as a whole.

Further, the electrolyte layer 4 is provided in an area on the front side of the metal support 1 that is larger than the area in which the through hole 1a is provided. That is, the through hole 1a is formed inside the region 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 intermediate layer 3 around the electrolyte layer 4 . To explain, when the metal supported electrochemical element E is used as a component of an SOFC, gas is supplied from the back side of the metal support 1 to the electrode layer 2 through the through hole 1a during operation of the SOFC. At the portion where the electrolyte layer 4 is in contact with the metal support 1, gas leakage can be suppressed without providing a separate member such as a gasket. In this embodiment, the electrode layer 2 is entirely covered with the electrolyte layer 4, but the electrolyte layer 4 may be provided above the electrode layer 2 and the intermediate layer 3, and a gasket or the like may be provided around the electrolyte layer 4.

Materials for the electrolyte layer 4 include YSZ (yttria-stabilized zirconia), SSZ (scandium-stabilized zirconia), GDC (gadolinium-doped ceria), YDC (yttrium-doped ceria), and SDC (samarium-doped ceria). An electrolyte material that conducts oxygen ions, such as LSGM (lanthanum gallate added with strontium/magnesium), or an electrolyte material that conducts hydrogen ions, such as a perovskite oxide, can be used. In particular, zirconia ceramics are preferably used. If the electrolyte layer 4 is made of zirconia-based ceramics, the operating temperature of the SOFC using the metal-supported electrochemical element E can be made higher than that of ceria-based ceramics or various hydrogen ion conductive materials. For example, when the metal-supported electrochemical element E is used in a SOFC as in this embodiment, a material such as YSZ that can exhibit high electrolyte performance even in a high temperature range of about 650° C. or higher is used as the material of the electrolyte layer 4. If the raw fuel of the system is a hydrocarbon-based raw fuel such as city gas or LPG, and the raw fuel is used as the anode gas of the SOFC through steam reforming, etc., the heat generated in the SOFC cell stack can be used as the raw fuel gas. It is possible to construct a highly efficient SOFC system for use in the reforming of Note that in this embodiment, the electrolyte layer 4 contains stabilized zirconia.

The electrolyte layer 4 can be formed using a low-temperature firing method (for example, a wet method using a firing treatment in a low-temperature range without firing treatment in a high-temperature range exceeding 1100°C) or a spray coating method (thermal spraying method, aerosol deposition method, aerosol gas deposition method). It is preferable to form by a method such as a powder jet deposition method, a powder jet deposition method, a particle jet deposition method, a cold spray method, etc.), a PVD method (sputtering method, a pulsed laser deposition method, etc.), a CVD method, or the like. By using these film forming processes that can be used in a low temperature range, a dense electrolyte layer 4 with high airtightness and gas barrier properties can be obtained without using baking at a high temperature range exceeding 1100° C., for example. Therefore, damage to the metal support 1 can be suppressed, and elemental diffusion between the metal support 1 and the electrode layer 2 can be suppressed, and a metal support type electrochemical element E with excellent performance and durability can be realized. . In particular, it is preferable to use a low-temperature firing method, a spray coating method, or the like because a low-cost element can be realized. Furthermore, it is more preferable to use a spray coating method because it is easy to obtain a dense electrolyte layer 4 having high airtightness and gas barrier properties in a low temperature range.

The electrolyte layer 4 is densely constructed to block gas leaks 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, its density is preferably 95% or more, more preferably 98% or more. Further, when the electrolyte layer 4 is composed of a plurality of layers, it is preferable that at least a part of the layers includes a layer having a density of 98% or more (dense electrolyte layer), and preferably 99% or more. It is more preferable to include a layer (dense electrolyte layer) having the above structure. If such a dense electrolyte layer is included in a part of the electrolyte layer, even if the electrolyte layer is composed of multiple layers, it will form a dense electrolyte layer with high airtightness and gas barrier properties. This is because it is easy to do.

(reaction prevention layer)
The reaction prevention layer 5 can be formed as a thin layer on the electrolyte layer 4 . When forming a thin layer, the thickness can be, for example, about 1 μm to 100 μm, preferably about 2 μm to 50 μm, more preferably about 3 μm to 15 μm. With such a thickness, sufficient performance can be ensured while reducing the amount of expensive reaction prevention layer material used and reducing costs.

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

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

When the reaction prevention layer 5 is formed using a method that can be formed at a processing temperature of 1100° C. or lower, damage to the metal support 1 can be suppressed and element diffusion between the metal support 1 and the electrode layer 2 can be prevented. This is preferable because it is possible to realize a metal-supported electrochemical element E with excellent performance and durability. For example, low-temperature firing methods (e.g., wet methods that use firing treatment in a low temperature range without firing treatment in a high temperature range exceeding 1100°C), spray coating methods (thermal spraying methods, aerosol deposition methods, aerosol gas deposition methods, A method such as a powder jet deposition method, a particle jet deposition method, a cold spray method, etc.), a PVD method (a sputtering method, a pulsed laser deposition method, etc.), a CVD method, etc. can be used as appropriate. In particular, it is preferable to use a low-temperature firing method, a spray coating method, or the like because a low-cost element can be realized. Furthermore, it is even more preferable to use a low-temperature firing method because the raw materials can be easily handled.

(Counter electrode layer)
The counter electrode layer 6 can be formed as a thin layer on the reaction prevention layer 5 . When forming a thin layer, the thickness can be, for example, about 1 μm to 100 μm, preferably 5 μm to 50 μm. With such a thickness, sufficient electrode performance can be ensured while reducing the amount of expensive counter electrode layer material used to reduce costs.

As the material for the counter electrode layer 6, for example, composite oxides such as LSCF and LSM, ceria-based oxides, and mixtures thereof can be used. In particular, it is preferable that the counter electrode layer 6 contains a perovskite oxide containing two or more elements selected from the group consisting of La, Sr, Sm, Mn, Co, and Fe. The counter electrode layer 6 made of the above materials functions as a cathode.

Note that if the formation of the counter electrode layer 6 is performed using a method that can be formed at a processing temperature of 1100° C. or lower, damage to the metal support 1 can be suppressed, and the elements of the metal support 1 and the electrode layer 2 can be formed. This is preferable because diffusion can be suppressed and a metal-supported electrochemical element E with excellent performance and durability can be realized. For example, low-temperature firing methods (e.g., wet methods that use firing treatment in a low temperature range without firing treatment in a high temperature range exceeding 1100°C), spray coating methods (thermal spraying methods, aerosol deposition methods, aerosol gas deposition methods, A method such as a powder jet deposition method, a particle jet deposition method, a cold spray method, etc.), a PDV method (a sputtering method, a pulsed laser deposition method, etc.), a CVD method, etc. can be used as appropriate. In particular, it is preferable to use a low-temperature firing method, a spray coating method, or the like because a low-cost element can be realized. Furthermore, it is even more preferable to use a low-temperature firing method because the raw materials can be easily handled.

(Method for manufacturing metal-supported electrochemical device)
Next, a method for manufacturing the metal-supported electrochemical device E will be described. The method for manufacturing the metal-supported electrochemical device E according to the present embodiment includes 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, and the electrode layer forming step The method includes an electrode layer lamination step, a degreasing step, and a baking step. The electrode layer forming step in this embodiment corresponds to an electrode layer forming method.

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

When the electrode layer forming step is performed by a low-temperature firing method, specifically, it is performed as in the following example. First, a material paste is prepared by mixing the material powder of the electrode layer 2 and a solvent (dispersion medium), and the material paste is applied to the front surface of the metal support 1 (electrode layer lamination step). Next, the electrode layer 2 is compression molded (electrode layer smoothing step) and heated at a predetermined temperature (degreasing step). Thereafter, it is fired at a temperature of 1100° C. or lower (firing step). Compression molding of the electrode layer 2 can be performed by, for example, CIP (Cold Isostatic Pressing) molding, roll pressure molding, RIP (Rubber Isostatic Pressing) molding, etc. can. Furthermore, the order of the electrode layer smoothing step and the electrode layer baking step can be changed. Note that the electrode layer smoothing step can also be performed by performing lapping, leveling, surface cutting/polishing, or the like. Further, the degreasing step is preferably a step of heating at a temperature of 150° C. or higher and 650° C. or lower. By performing the degreasing step, defects in film formation of the electrode layer 2 due to dirt such as oil and fat can be suppressed.

Further, in this embodiment, when the firing step in the electrode layer forming step is performed, a metal oxide layer 1b (diffusion prevention layer) is formed on the surface of the metal support 1. Incidentally, before performing the firing step in the electrode layer forming step, a step of forming a diffusion prevention layer may be performed separately.

In this embodiment, the firing step is performed in an atmosphere adjusted such that the partial pressure of oxygen is 4.0×10 ⁻⁸ bar or more and 4.0×10 ⁻⁶ bar or less. As described above, by performing the firing step in an atmosphere in which the partial pressure of oxygen is 4.0×10 ⁻⁸ bar or more and 4.0×10 ⁻⁶ bar or less, the electrode layer ² can be It has tensile strength. Therefore, the electrode layer 2 becomes difficult to peel off from the metal support 1, and the adhesion strength with the intermediate layer 3 formed in the intermediate layer forming step described later becomes high, so the metal supported electrochemical element has excellent durability. E can be achieved. The partial pressure of oxygen is preferably 7.5×10 ⁻⁸ bar or more and 3.0×10 ⁻⁶ bar or less, and preferably 2.9×10 ⁻⁷ bar or more and 1.5×10 ⁻⁶ bar or less. It is more preferable. If the partial pressure of oxygen is too low or too high, the tensile strength of the electrode layer 2 will decrease, and the electrode layer 2 will easily peel off from the metal support 1.

Specifically, the firing step is performed in an inert gas atmosphere with a dew point of 10° C. or more and 70° C. or less without supplying hydrogen. By having a dew point of 10° C. or more and 70° C. or less, when the metal support 1 is heated to a firing temperature that does not deteriorate, the firing is performed at a partial pressure of oxygen of 4.0×10 ⁻⁸ bar or more and 4.0× This can be carried out in an atmosphere of 10 ⁻⁶ bar or less. As mentioned above, the dew point is preferably 10°C or more and 70°C or less, more preferably 20°C or more and 60°C or less. Further, as the inert gas, for example, nitrogen can be used.

Further, the firing step is performed at a temperature of 800° C. or more and 1100° C. or less in order to suppress deterioration of the metal support 1. In particular, it is preferably carried out at a temperature of 1050°C or lower, more preferably 1000°C or lower.

(Intermediate layer formation step)
In the intermediate layer forming step, a thin intermediate layer 3 is formed on the electrode layer 2 so as to cover the electrode layer 2 . The intermediate layer 3 can be formed using the film forming method described above, but in order to suppress deterioration of the metal support 1, it is preferable to use a film forming method that can be used in a low temperature range of 1100° C. or lower.

When the intermediate layer forming step is performed by a low temperature firing method, specifically, it is performed as in the following example. First, a material paste is prepared by mixing the material powder for the intermediate layer 3 and a solvent (dispersion medium), and is applied to the front surface of the electrode layer 2 . Then, the intermediate layer 3 is compression molded (intermediate layer smoothing step) and fired at 1100° C. or lower (intermediate layer firing step). Compression molding of the intermediate layer 3 can be performed by, for example, CIP molding, roll pressure molding, RIP molding, or the like. Further, 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, at such a temperature, a high-strength intermediate layer 3 can be formed while suppressing damage and deterioration of the metal support 1. Further, it is more preferable to bake the intermediate layer 3 at a temperature of 1050°C or lower, and even more preferable to carry out the firing at a temperature of 1000°C or lower. This is because the lower the firing temperature of the intermediate layer 3 is, the more the metal support type electrochemical element E can be formed while the damage and deterioration of the metal support body 1 is further suppressed. Note that the order of the intermediate layer smoothing step and the intermediate layer firing step can also be changed. Further, the intermediate layer smoothing step can also be performed by performing lapping, leveling, surface cutting/polishing, or the like.

(Electrolyte layer formation step)
In the electrolyte layer forming step, the electrolyte layer 4 is formed in a thin layer on the intermediate layer 3 while covering the electrode layer 2 and the intermediate layer 3 . For forming the electrolyte layer 4, the above-mentioned film forming method that can be used in the low temperature range can be used, but it is preferable to use a spray coating method. In particular, in order to form a high-quality electrolyte layer 4 that is dense and has high airtightness and gas barrier performance in a temperature range of 1100°C or lower, aerosol deposition method, aerosol gas deposition method, powder jet deposition method, particle jet deposition method, etc. More preferably, one of the position methods is used. In this embodiment, the electrolyte layer 4 is formed using an aerosol deposition method. Specifically, an aerosolized material powder for the electrolyte layer 4 (in this embodiment, fine powder of stabilized zirconia such as YSZ or SSZ) is injected toward the intermediate layer 3 on the metal support 1 to form the electrolyte layer 4. form.

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

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

As described above, the electrode layer 2 has a tensile strength of 1.2 MN/ ^m2 or more, the adhesion between the electrode layer 2 and the metal support 1 and the intermediate layer 3 is improved, and the strength (reliability) is improved. ), a metal-supported electrochemical element E with excellent durability and performance can be manufactured. Further, when firing the electrode layer 2 of this metal-supported electrochemical element E, there is no need to supply hydrogen, so the equipment cost required for manufacturing can be suppressed.

(Solid oxide fuel cell)
By configuring the metal-supported electrochemical device E as described above, the metal-supported electrochemical device E can be used as a power generation cell of a solid oxide fuel cell. In other words, it is possible to realize a solid oxide fuel cell in which the metal-supported electrochemical element E generates a power generation reaction.

For example, a fuel gas containing hydrogen as a first gas is passed from the back surface of the metal support 1 through the through hole 1a to the electrode layer 2, air is passed as a second gas to the counter electrode layer 6, and a predetermined amount of gas is passed through the through hole 1a. Maintain operating temperature (eg, 500°C or higher and 900°C or lower). Then, when an electrolyte material that conducts oxygen ions is used in the electrolyte layer 4, oxygen O ₂ contained in the air reacts with electrons e ⁻ in the counter electrode layer 6 to generate oxygen ions O ²⁻ . The oxygen ions O ^2- move to the electrode layer 2 through the electrolyte layer 4 . In the electrode layer 2, hydrogen H ₂ contained in the flowing fuel gas reacts with oxygen ions O ^{2 -} to generate water H ₂ O and electrons e ^- .

When an electrolyte material that conducts hydrogen ions is used for the electrolyte layer 4, hydrogen H ₂ contained in the fuel gas flowing in the electrode layer 2 releases electrons e ⁻ to generate hydrogen ions H ⁺ . The hydrogen ions H ⁺ move to the counter electrode layer 6 through the electrolyte layer 4 . In the counter electrode layer 6, oxygen O ₂ contained in the air, hydrogen ions H ⁺ , and electrons e ⁻ react to generate water H ₂ O.

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

In addition, solid oxide fuel cells that can operate in a temperature range of 650°C or higher during rated operation can be used to convert raw fuel into hydrogen in fuel systems that use hydrocarbon gas such as city gas as raw fuel. This is more preferable because it is possible to construct a system in which the heat required for the fuel cell system can be covered by the exhaust heat of the fuel cell, and the power generation efficiency of the fuel cell system can be increased. In addition, it is more preferable to use a solid oxide fuel cell that operates at a temperature of 900°C or lower during rated operation because the effect of suppressing Cr volatilization from the metal-supported electrochemical element E is enhanced. A solid oxide fuel cell operated in a temperature range of .degree. C. or lower is more preferable because the effect of suppressing Cr volatilization can be further enhanced.

(Electrochemistry module)
Next, the electrochemical module M will be explained with reference to FIG. The electrochemical module M includes a metal supported electrochemical element E in which a cylindrical support is formed by a metal support 1 and a U-shaped member 9 attached to the back surface of the metal support 1. A plurality of these metal-supported electrochemical elements E are laminated (multiple sets) with the current collecting member 26 in between to form an electrochemical module M. In this embodiment, the current collecting member 26 is joined to the counter electrode layer 6 and the U-shaped member 9 of the metal-supported electrochemical element E, and electrically connects them. The counter electrode layer 6 of the chemical element E and the U-shaped member 9 may be directly electrically connected.

The electrochemical module M also includes a gas manifold 17, a termination member, and a current extraction section. One open end of the cylindrical support is connected to the gas manifold 17, and the metal-supported electrochemical element E, which is a plurality of stacked metal-supported electrochemical elements, is supplied with gas from the gas manifold 17. The supplied gas flows through the inside of the cylindrical support, passes through the through hole 1a of the metal support 1, and is supplied to the electrode layer 2.

(Electrochemical equipment and energy system)
Next, with reference to FIG. 3, an electrochemical device Y and an energy system Z constructed using the electrochemical module M will be described.

As shown in FIG. 3, the energy system Z includes an electrochemical device Y and a heat exchanger 53 as an exhaust heat utilization section that reuses the heat distributed from the electrochemical device Y.

In this embodiment, the electrochemical device Y includes an electrochemical module M, a fuel converter including a desulfurizer 31 and a reformer 34, and a reducing component generated by the fuel converter for the electrochemical module M. The electrochemical module M has a fuel supply section 46 that supplies fuel gas, and an inverter 38 that is a type of power converter and serves as an output section that extracts electric power from the electrochemical module M.

More specifically, the electrochemical device Y includes a desulfurizer 31, a reformed water tank 32, a vaporizer 33, a reformer 34, a blower 35, a combustion section 36, an inverter 38, a control section 39, and an electrochemical module M. , a storage container 40, etc.

The desulfurizer 31 removes (desulfurizes) sulfur compound components contained in hydrocarbon raw fuel such as city gas. When sulfur compounds are contained in the raw fuel, the influence of the sulfur compounds on the reformer 34 or the metal-supported electrochemical element E can be suppressed by providing the desulfurizer 31. The vaporizer 33 generates water vapor from reformed water supplied from the reformed water tank 32. The reformer 34 steam-reforms the raw fuel desulfurized by the desulfurizer 31 using the steam generated by the vaporizer 33 to generate reformed gas containing hydrogen.

The electrochemical module M uses the reformed gas supplied from the reformer 34 and the air supplied from the blower 35 to perform an electrochemical reaction and generate electricity. The combustion section 36 mixes the reaction exhaust gas discharged from the electrochemical module M with air, and burns the combustible components in the reaction exhaust gas.

The electrochemical module M includes a plurality of metal-supported electrochemical elements E and a gas manifold 17. The plurality of metal-supported electrochemical elements E are arranged in parallel and electrically connected to each other, and one end (lower end) of the 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 the air supplied from the blower 35.

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

The vaporizer 33, the reformer 34, the electrochemical module M, and the combustion section 36 are housed in the housing container 40. The reformer 34 then performs a reforming process on the raw fuel using the combustion heat generated by combustion of the reaction exhaust gas in the combustion section 36.

The raw fuel is supplied to the desulfurizer 31 through the raw fuel supply path 42 by the operation of the boost pump 41 . The reformed water in the reformed water tank 32 is supplied to the vaporizer 33 through the reformed water supply path 44 by the operation of the reformed water pump 43 . The raw fuel supply path 42 is merged with the reformed water supply path 44 at a downstream side of the desulfurizer 31, and the reformed water and raw fuel that are combined outside the storage container 40 are fed into the storage container. 40 is supplied to the vaporizer 33 provided in the interior.

The reformed water is vaporized in the vaporizer 33 and becomes water vapor. The raw fuel containing steam generated in the vaporizer 33 is supplied to the reformer 34 through a steam-containing raw fuel supply path 45 . The raw fuel is steam-reformed in the reformer 34, and a reformed gas (first gas having a reducing component) containing hydrogen gas as a main component is generated. The reformed gas generated in the reformer 34 is supplied to the gas manifold 17 of the electrochemical module M through the fuel supply section 46.

The reformed gas supplied to the gas manifold 17 is distributed to the plurality of metal-supported electrochemical elements E, and the reformed gas is distributed to the metal-supported electrochemical elements E from the lower end, which is the connection between the metal-supported electrochemical element E and the gas manifold 17. It is supplied to chemical element E. Mainly hydrogen (reducing component) in the reformed gas is used in the electrochemical reaction in the metal-supported electrochemical element E. Reaction exhaust gas containing residual hydrogen gas not used in the reaction is discharged from the upper end of the metal-supported electrochemical element E to the combustion section 36.

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

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 an exhaust heat utilization section that reuses the heat discharged from the electrochemical device Y.

Note that instead of the exhaust heat utilization section, a reaction exhaust gas utilization section that utilizes the reaction exhaust gas discharged (without being combusted) from the electrochemical module M may be provided. The reaction exhaust gas contains residual hydrogen gas that was not used in the reaction in the metal-supported electrochemical element E. In the reaction exhaust gas utilization section, the remaining hydrogen gas is utilized for heat utilization through combustion and power generation using a fuel cell or the like, thereby effectively utilizing energy.

[Example/Comparative example]
Examples and comparative examples will be described below.

[Formation of electrode layer]
As Example 1, a metal support 1 was produced by providing a plurality of through holes 1a in a 2.5 mm radius area from the center of a circular metal plate with a thickness of 0.3 mm and a diameter of 25 mm by laser processing.

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

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

Thereafter, the degreased metal support 1 was heated under a humidified nitrogen gas atmosphere with a dew point temperature of 20°C and a firing temperature of 850°C and an oxygen partial pressure of 7.27×10 ⁻⁸ bar. A time firing process was performed (baking step).

For Examples 2 to 7 and Comparative Examples 1 and 2, the same procedure was followed except that the firing temperature, dew point temperature, and oxygen partial pressure in the firing step were changed to the conditions shown in Table 1 below. An electrode layer 2 was formed thereon.

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

First, I attached a hook-shaped attachment to the tip of an RS PRO force gauge (model: 111-3690), and hooked a round bolt to the tip of the hook. The force gauge was then fixed vertically on a flat stand whose height could be adjusted using a handle. Two screw holes were drilled in the flat part of the flat stand so that screws with washers could be attached to them. The metal support 1 on which the electrode layer 2 was laminated in the center was placed on a flat table, and the part of the metal support 1 where the electrode layer 2 was not formed was sandwiched between a washer and the flat table and fixed with screws. The tip of a set screw was adhered to the electrode layer 2 formed on the metal support 1 with an adhesive. A spacer was attached to the tip of the set screw that was not connected to the electrode layer 2, and connected to a round bolt hooked onto the tip of the force gauge. Thereafter, the electrode layer 2 was pulled in the vertical direction while adjusting the height of the force gauge, and the load applied until it peeled off from the metal support 1 was measured. The obtained load was multiplied by the gravitational acceleration to convert the unit into N. Furthermore, the area where the adhesive was in contact with the electrode layer 2 was measured using an optical microscope, and the measured area was calculated. The tensile strength N/m ² was calculated by dividing the load applied until peeling by the measurement area.

The results of tensile strength measurements are summarized in Table 1. As can be seen from Table 1, for Examples 1 to 7 in which the oxygen partial pressure during firing was 4.0 × 10 ^-8 bar to 4.0 × 10 ^-6 bar, the tensile strength was 1.2 MN. / ^m2 or more, which is a high value. On the other hand, Comparative Example 1, in which the oxygen partial pressure during firing was less than 4.0×10 ⁻⁸ bar, and Comparative Example 2, in which the oxygen partial pressure was greater than 4.0×10 ⁻⁶ bar, both had a tensile strength similar to that of Example 1. This is extremely low compared to ~7.

[Formation of intermediate layer]
Further, for Examples 1 to 7 and Comparative Examples 1 and 2, the electrode layer 2 was formed on the metal support 1 in the same manner as above, and then 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 the paste, an 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. Thereafter, the metal support 1 on which the intermediate layer 3 was laminated was compression molded and then subjected to a firing treatment to form an intermediate layer 3 having a flat surface (intermediate layer forming step).

As a result of forming the intermediate layer 3 in the intermediate layer forming step as described above, as shown in Table 1, the oxygen partial pressure during firing was 4.0 × 10 ^-8 bar or more and 4.0 × 10 ^-6 bar or less. In Examples 1 to 7, no peeling of the intermediate layer 3 was observed, while in Comparative Examples 1 and 2, in which the oxygen partial pressure during firing was outside the above range, the intermediate layer 3 was peeled off. Note that FIGS. 4 to 6 are images taken of the metal support 1 after the intermediate layer forming step. FIG. 4 is an image of Example 4, and FIG. 5 is an image of Example 6, and it can be seen that the intermediate layer 3 is not peeled off. On the other hand, FIG. 6 is an image related to Comparative Example 2, and the white area in the image is the electrode layer 2 that appeared due to the peeling of the intermediate layer 3.

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

[2] In the above embodiment, the dew point is 10°C or more and 70°C or less, the firing temperature is 800°C or more and 1100°C or less, and the firing is performed at an oxygen partial pressure of 4.0×10 ⁻⁸ bar or more and 4.0×10 −8 bar or more ^. Although the process is carried out under an atmosphere of ⁶ bar or less, the present invention is not limited thereto. The partial pressure of oxygen is determined by changing the dew point and firing temperature as parameters. Therefore, as long as the atmosphere during firing has an oxygen partial pressure of 4.0 x 10 ^-8 bar or more and 4.0 x 10 ^-6 bar or less, the dew point and firing temperature do not necessarily have to be within the above range. Either or both of the dew point and firing temperature may be set to a value outside the above range so as to obtain a desired oxygen partial pressure.

[3] In the above embodiment, when manufacturing the metal-supported electrochemical device E, the intermediate layer formation step and the reaction prevention layer formation step are performed, so that the metal-supported electrochemical device E does not have the intermediate layer 3 or the reaction prevention layer 5. Although the present invention is not limited to this embodiment, an embodiment may be adopted in which neither the intermediate layer 3 nor the reaction prevention layer 5 is provided. In addition, in the case where the intermediate layer 3 is not provided, the electrolyte layer 4 is formed on the electrode layer 2, and in the case where the reaction prevention layer 5 is not provided, the counter electrode is formed on the electrolyte layer 4. The electrode layer 6 is now formed.

[4] In the above embodiment, the metal-supported electrochemical device E was used in a solid oxide fuel cell, but this metal-supported electrochemical device E can also be used in a solid oxide electrolytic cell or a solid oxide electrolytic cell. It can also be used for oxygen sensors, etc.
When the metal supported electrochemical element E is operated as an electrolytic cell, a gas containing water vapor or carbon dioxide is passed through the electrode layer 2, and a voltage is applied between the electrode layer 2 and the counter electrode layer 6. Then, the electron e ^- reacts with water H ₂ O and carbon dioxide molecule CO ₂ in the electrode layer 2, and becomes hydrogen H ₂ , carbon monoxide CO, and oxygen ion O ^{2 -} . Oxygen ions O ²⁻ move through the electrolyte layer 4 to the counter electrode layer 6 . Then, in the counter electrode layer 6, the oxygen ions O ^2- release electrons and become oxygen O ₂ . Through the above reaction, water H ₂ O is electrolyzed into hydrogen H ₂ and oxygen O ₂ . When a gas containing carbon dioxide molecules CO ₂ is passed through, it is electrolyzed into carbon monoxide CO and oxygen O ₂ .
FIG. 7 shows an example of an electrochemical device Y1 and an energy system Z1 in which the metal-supported electrochemical element E is operated as an electrolytic cell that generates gas by the electrolytic reaction described above. As shown in the figure, the energy system Z1 includes an electrochemical device Y1 and two heat exchangers 90 and 92 as an exhaust heat utilization section that reuses the heat distributed from the electrochemical device Y1.
In this embodiment, the electrochemical device Y1 distributes electric power to the electrochemical module M, a fuel converter 91 that synthesizes hydrocarbons based on hydrogen generated in the electrochemical module M, and the electrochemical module M. It has a power converter 93.
In this electrochemical device Y1, an electrochemical module M includes a plurality of metal-supported electrochemical elements E and two gas manifolds 17 and 171. The plurality of metal-supported electrochemical elements E are arranged in parallel and electrically connected to each other. The metal supported electrochemical element E has one end (lower end) fixed to the gas manifold 17 and the other end (upper end) fixed to the gas manifold 171. A gas manifold 17 at one end of the metal-supported electrochemical element E is supplied with water vapor and carbon dioxide. Hydrogen, carbon monoxide, etc. generated by the above-mentioned reaction in the metal-supported electrochemical element E are collected by a gas manifold 171 communicating with the other end.
Further, in this embodiment, the heat exchanger 90 is operated as an exhaust heat utilization unit that exchanges and vaporizes water and the reaction heat generated by the reaction that occurs in the fuel converter 91, and the heat exchanger 92 is operated as a waste heat utilization unit that vaporizes water. Energy efficiency can be improved by operating as an exhaust heat utilization section that performs heat exchange between the exhaust heat generated by the supported electrochemical element E and water vapor and carbon dioxide for preheating.
Further, the power converter 93 distributes power to the metal-supported electrochemical element E of the electrochemical module M. Thereby, the metal-supported electrochemical element E acts as an electrolytic cell.
Therefore, according to the above configuration, it is possible to realize the electrochemical device Y1 and the energy system Z1 that can improve the efficiency of converting electrical energy into chemical energy such as fuel.

[5] In the above embodiment, a plurality of metal-supported electrochemical elements E are used in combination as the electrochemical module M, but the present invention is not limited to this, and it is also possible to use them alone.

[6] In the above embodiments, the energy systems Z and Z1 are provided with an exhaust heat utilization section that reuses the heat discharged from the electrochemical devices Y and Y1, but the present invention is not limited to this. It may also be an embodiment that does not include a heat utilization section.

[7] In the above embodiment, a composite material such as NiO-GDC, Ni-GDC, NiO-YSZ, Ni-YSZ, CuO-CeO ₂ , Cu-CeO ₂ is used as the material of the electrode layer 2, and the counter electrode layer For example, a composite oxide such as LSCF or LSM is used as the material of 6, hydrogen gas is passed through the electrode layer 2 to form a fuel electrode (anode), air is passed through the counter electrode layer 6 to form an air electrode (cathode), Although the embodiment has been described in which it is used as a power generation cell of a solid oxide fuel cell, it is not limited thereto. Such a configuration may be modified to configure the metal-supported electrochemical element E so that the electrode layer 2 can be used as an air electrode and the counter electrode layer 6 can be used as a fuel electrode. That is, as the material of the electrode layer 2, for example, a composite oxide such as LSCF or LSM is used, and as the material of the counter electrode layer 6, for example, NiO-GDC, Ni-GDC, NiO-YSZ, Ni-YSZ, CuO-CeO ₂ , a composite material such as Cu-CeO ₂ is used. In the metal-supported electrochemical element E configured as described above, air is passed through the electrode layer 2 to serve as an air electrode, hydrogen gas is passed through the counter electrode layer 6 to serve as a fuel electrode, and the metal-supported electrochemical element E can be used as a power generation cell of a solid oxide fuel cell.

[8] In the above embodiment, the electrochemical module M is a metal-supported electrochemical module in which a cylindrical support is formed by the metal support 1 and the U-shaped member 9 attached to the back surface of the metal support 1. Although the embodiment includes the element E, the embodiment is not limited to this. For example, as shown in FIG. 8, an electrochemical module M may be configured by stacking metal-supported electrochemical elements E with inter-cell connection members 71 interposed therebetween.
In this case, the inter-cell connecting member 71 is a plate-like member that is electrically conductive and not gas permeable, and grooves 72 that are orthogonal to each other are formed on the front and back surfaces. Note that the inter-cell connection member 71 may be made of metal such as stainless steel or metal oxide.
Then, by stacking the metal-supported electrochemical elements E with the inter-cell connection member 71 in between, gas can be supplied to the metal-supported electrochemical elements E through the grooves 72. Specifically, the groove 72 formed on one surface serves as a first gas flow path 72a, and gas is supplied to the front side of the metal supported electrochemical element E, that is, the counter electrode layer 6. In addition, the groove 72 formed on the other surface becomes a second gas flow path 72b, and gas flows from the back side of the metal supported electrochemical element E, that is, the back side of the metal support 1, to the electrode layer 2 through the through hole 1a. supply.
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. Then, a power generation reaction progresses in the metal-supported electrochemical element E, and an electromotive force and current are generated. The generated power is extracted to the outside of the electrochemical module M from the inter-cell connection members 71 at both ends of the stacked metal-supported electrochemical element E.
Note that the grooves 72 formed on the front surface and the grooves formed on the back surface of the inter-cell connection member 71 may be parallel to each other.

[9] In the above embodiment, the metal-supported electrochemical device E is mainly used in a flat plate type or a cylindrical flat type solid oxide fuel cell, but is not limited to this. It can also be used in elements such as oxide fuel cells.

[10] In the above embodiment, the electrochemical device Y includes the electrochemical module M having a plurality of metal-supported electrochemical elements E, but the present invention is not limited to this. For example, the electrochemical device may include one metal-supported electrochemical element E.

It should be noted that the configuration disclosed in the above embodiment (including other embodiments, the same applies hereinafter) can be applied in combination with the configuration disclosed in other embodiments, as long as there is no contradiction, and The embodiments disclosed in this specification are illustrative, and the embodiments of the present invention are not limited thereto, and can be modified as appropriate without departing from the purpose of the present invention.

1: Metal support 1b: Metal oxide film (diffusion prevention layer)
2: Electrode layer 3: Intermediate layer 4: Electrolyte layer 5: Reaction prevention layer 6: Counter electrode layer 31: Desulfurizer (fuel converter)
34: Reformer (fuel converter)
38: Inverter (power converter)
53: Heat exchanger (exhaust heat utilization part)
90, 92: Heat exchanger (exhaust heat utilization part)
91: Fuel converter 93: Power converter E: Metal supported electrochemical element M: Electrochemical module Y, Y1: Electrochemical device Z, Z1: Energy system

Claims (19)

A method of forming an electrode layer on a metal support, the method comprising:
an electrode layer lamination step of laminating an electrode layer on the metal support;
a firing step of firing the electrode layer laminated on the metal support,
The method for forming an electrode layer, wherein the firing step is performed in an atmosphere with an oxygen partial pressure of 4.0×10 ⁻⁸ bar or more and 4.0×10 ⁻⁶ bar or less. The electrode layer forming method according to claim 1, wherein the firing step is performed under an inert gas atmosphere having a dew point of 10°C or more and 70°C or less. The electrode layer forming method according to claim 2, wherein the inert gas is nitrogen. The electrode layer forming method according to any one of claims 1 to 3, wherein the firing step is performed at a temperature of 800° C. or higher and 1100° C. or lower. 5. The electrode layer forming method according to claim 1, wherein a degreasing step for removing oil is performed before the firing step. The electrode layer forming method according to claim 5, wherein the degreasing step is performed at a temperature of 150°C or more and 650°C or less. An electrode layer formed on a metal support and having a tensile strength of 1.2 MN/m ² or more. The electrode layer according to claim 7, comprising at least one selected from nickel-based compounds, ceria-based oxides, zirconia-based oxides, and perovskite-based composite oxides, or a combination thereof. The electrode layer according to claim 7 or 8, having a porosity of 5% or more. The electrode layer according to any one of claims 7 to 9, which is formed on a diffusion prevention layer formed on the metal support. The electrode layer according to claim 10, wherein the thickness of the diffusion prevention layer is 3 μm or less. The electrode layer according to any one of claims 7 to 11,
an electrolyte layer disposed on the electrode layer;
An electrochemical device comprising at least a counter electrode layer disposed on the electrolyte layer. The electrochemical device according to claim 12, further comprising an intermediate layer between the electrode layer and the electrolyte layer. An electrochemical module in which a plurality of the electrochemical elements according to claim 12 or 13 are arranged in a group. A solid oxide fuel cell comprising the electrochemical element according to claim 12 or 13, wherein the electrochemical element generates a power generation reaction. A solid oxide electrolytic cell comprising the electrochemical element according to claim 12 or 13, wherein the electrochemical element causes an electrolytic reaction. The electrochemical element according to claim 12 or 13 or the electrochemical module according to claim 14,
a fuel converter that generates a reducing component to be supplied to the electrochemical element or the electrochemical module, or converts a gas containing a reducing component that is generated in the electrochemical element or the electrochemical module; Electrochemical device with. The electrochemical element according to claim 12 or 13 or the electrochemical module according to claim 14,
An electrochemical device comprising at least a power converter that extracts electric power from the electrochemical element or the electrochemical module, or distributes electric power to the electrochemical element or the electrochemical module. The electrochemical device according to claim 17 or 18,
An energy system comprising at least an exhaust heat utilization section that reuses heat discharged from the electrochemical device.

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