JP2020095984A - Electrochemical element, electrochemical module, electrochemical device, energy system, solid oxide fuel cell, and method of manufacturing electrochemical element - Google Patents

Abstract

To achieve an electrochemical element increased in reliability and durability furthermore, high in strength and performance, and capable of being applied also for an SOFC.SOLUTION: An electrochemical element includes an electrode layer 2, an electrolyte layer 4, and a counter electrode layer 6. The material of the electrolyte layer 4 is a metal oxide. The electrolyte layer 4 is disposed between the electrode layer 2 and the counter electrode layer 6. An uneven structure site S1 including a recessed portion A1 and a projecting portion B1 is formed on an electrolyte layer upper side surface 4a that is a side of the counter electrode layer 6 in the electrolyte layer 4.SELECTED DRAWING: Figure 2

Description

The present invention relates to an electrochemical device having an electrode layer, an electrolyte layer and a counter electrode layer.

In a conventional electrolyte-supported solid oxide fuel cell (hereinafter referred to as “SOFC”), electrode-supported SOFC, or metal-supported SOFC, an electrode layer is formed on a flat electrolyte layer. It

Patent Document 1 discloses an electrolyte-supported SOFC in which a fuel electrode is formed on the surface of a YSZ pellet and an air electrode is formed on the back surface. In this SOFC, for example, a stress concentration portion having an uneven shape is provided on the electrode formed on the solid electrolyte to reduce thermal stress. On the contact surface between the solid electrolyte and the electrode, the uneven stress concentration portion is formed on the surface where the electrode layer contacts the interconnector so as not to impair the generated reaction.

Patent Document 2 describes a method for manufacturing an SOFC in which the applied electrolyte material is dried, then pressed and then fired to form an electrolyte layer. The upper surface of the electrolyte layer is formed to be extremely flat by pressing, as shown in FIG. Then, the electrode layer is formed on the electrolyte layer flattened by pressing. This manufacturing method is applicable not only to the case where the metal substrate is used as the support, but also to the case where the electrode is used as the support.

JP-A-5-82135 JP, 2008-234927, A

As shown in Patent Document 1, the difference in thermal expansion coefficient between the solid electrolyte material and the electrode material and the difference in thermal expansion coefficient between the interconnector material and the electrode material are different from each other. Thermal stress is applied between dissimilar materials when the temperature is raised or lowered during the production and/or operation of the electrodes for use, which causes problems such as deterioration of electrical properties, electrode peeling, and cell damage. The shape has been formed on the surface where the electrode layer contacts the interconnector, but detailed studies have not been made on the formation of the uneven shape on the surface of the electrolyte. However, in an electrochemical element such as SOFC, various stresses are exerted between the electrolyte layer, which is gas tight and needs to be densely formed to exhibit high ionic conductivity, and the porous electrode layer. Since it is easily received, various stresses at the interface between the electrolyte layer and the electrode layer, etc. are relaxed, and cell damage and the like are suppressed even during the production of the SOFC electrode/electrolyte laminate or the SOFC start/stop thermal cycle. There remains a problem of obtaining an electrochemical device having excellent reliability, durability, strength and performance. In particular, in the case of an electrochemical device such as SOFC that uses a zirconia-based electrolyte and operates in a high temperature range, solving the above-mentioned remaining problems has been important.
Further, in the method of Patent Document 2, in order to obtain a dense electrolyte at a low temperature, the electrolyte layer is applied and then pressed to obtain an electrolyte layer having a flat surface and a dense surface. However, the electrolyte layer and the electrode layer, etc. There remains the problem of relieving various stresses at the interface with and to obtain an electrochemical element having excellent reliability, durability, strength and performance.

The present invention has been made in view of the above problems, and an object of the present invention is to realize an electrochemical element having higher reliability and durability, high strength and high performance, which is applicable to SOFCs. ..

Characteristic configuration of the electrochemical device according to the present invention to achieve the above object, at least an electrode layer, an electrolyte layer and a counter electrode layer, the electrolyte layer, the material is a metal oxide, the electrode layer And the counter electrode layer, and at least on the electrolyte layer upper surface of the electrolyte layer on the side of the counter electrode layer in the electrolyte layer, a concave-convex structure portion including one or more recesses or protrusions is formed. There is a point.

The inventors of the present invention have, after intensive studies, thought that, unlike the prior art, forming a concavo-convex structure portion including at least one concave portion or convex portion on the upper surface of the electrolyte layer, which is at least the counter electrode layer side in the electrolyte layer. I arrived. By configuring the electrochemical element in this way, the presence of the uneven structure portion can increase the contact area between the electrolyte layer and the counter electrode layer (or the intermediate layer), and increase the adhesion strength between the layers. High performance can be obtained while relaxing various stress and improving reliability and durability.

In particular, in an electrochemical device having a thin electrolyte layer, securing reliability and durability is a problem, and its effect is great. Further, when a thin-layer electrochemical device is formed on a metal substrate as a support, the conventional method for forming a dense electrolyte layer by high-temperature firing at about 1400° C. or higher cannot be used. Although there were major issues in securing reliability/durability and performance/strength, this method produces a great effect.

In the present invention, when the direction perpendicular to the electrolyte layer is the height direction, and the direction orthogonal to the height direction is the in-plane direction,
A point where the distance in the in-plane direction from the apex of the recess is within 5 μm, and a height difference from the apex of the recess is 0.5 μm or more;
At least one of a point where the distance in the in-plane direction from the apex of the convex portion is within 5 μm, and a height difference from the apex of the convex portion is 0.5 μm or more. When it is configured to be included in the uneven structure portion, since the uneven structure portion of the electrolyte layer comes into contact with the laminate on the electrolyte layer such as the counter electrode layer, the adhesion strength between the electrolyte layer and the counter electrode layer, etc. It is preferable since it is possible to obtain high performance while reducing the various stresses and improving reliability and durability. If the height difference from the apex of the concave portion or the height difference from the apex of the convex portion is 3 μm or less, a counter electrode layer or the like is formed on the electrolyte layer while obtaining the above effect. It is preferable that the thickness is 2 μm or less because the layered product on the electrolyte layer such as the counter electrode layer can be easily thinned and the material cost of the counter electrode layer and the like can be reduced.

Further, in the present invention, when the direction perpendicular to the electrolyte layer is the height direction, a portion where the width in the height direction of the uneven structure portion is 5% or more of the thickness of the electrolyte layer is the uneven structure portion. If it is configured to be included in, the uneven structure portion of the electrolyte layer comes into contact with the laminate on the electrolyte layer such as the counter electrode layer, so that the adhesion strength between the electrolyte layer and the counter electrode layer, etc. is increased. In addition to being able to reduce stresses and improve reliability and durability, it is possible to obtain high performance, which is preferable, and the portion having a thickness of 10% or more of the thickness of the electrolyte layer is the uneven structure. It is more preferable to be configured to be included in the part because the above-described effect can be obtained more greatly. When the width in the height direction of the uneven structure portion is 30% or less of the thickness of the electrolyte layer, it becomes easy to stack a counter electrode layer or the like on the electrolyte layer while obtaining the above effects. Therefore, it is preferable.

Further, in the present invention, when the uneven structure portion includes a portion having a surface roughness (Sa) of 0.3 μm or more, the uneven structure portion of the electrolyte layer is formed on the electrolyte layer such as the counter electrode layer. Since it comes into contact with the laminate, the adhesion strength between the electrolyte layer and the counter electrode layer, etc. can be increased, and various stresses can be relieved to improve reliability and durability while achieving high performance. It is possible because it is possible. The surface roughness (Sa) in the present application is a value in the range of 10 μm square. In addition, when the surface roughness (Sa) is 1.5 μm or less, it is easy to stack a counter electrode layer or the like on the electrolyte layer while obtaining the above effects, and it is preferable that the surface roughness (Sa) is 1 μm or less. It is more preferable because the laminate on the electrolyte layer such as the electrode layer can be easily thinned and the material cost of the counter electrode layer and the like can be reduced.

Another characteristic configuration of the electrochemical element according to the present invention is that the counter electrode layer is formed in contact with the electrolyte layer upper side surface of the electrolyte layer, and the concavo-convex structure portion is in contact with the counter electrode layer. It is in.

According to the above characteristic configuration, since the uneven structure portion of the electrolyte layer is in contact with the counter electrode layer, it is possible to increase the adhesion strength between the electrolyte layer and the counter electrode layer, and relax various stresses. It is preferable because high performance can be obtained while improving reliability and durability.

Another characteristic configuration of the electrochemical device according to the present invention has an intermediate layer disposed between the electrolyte layer and the counter electrode layer, the intermediate layer contacting the electrolyte layer upper surface of the electrolyte layer. And the uneven structure portion is in contact with the intermediate layer.

According to the above characteristic configuration, since the uneven structure portion of the electrolyte layer is in contact with the intermediate layer, it is possible to increase the adhesion strength between the electrolyte layer and the intermediate layer, relax various stresses, and improve reliability. It is preferable because high performance can be obtained while improving the durability and durability.

Another characteristic configuration of the electrochemical element according to the present invention is that the intermediate layer is formed in contact with the counter electrode layer, and the intermediate layer upper side surface which is a surface of the intermediate layer on the counter electrode layer side is The point is that it is flat.

According to the above characteristic configuration, the intermediate layer does not need to be as dense as the electrolyte layer, so that the intermediate layer can be made porous to some extent, and some degree between the porous counter electrode layer and the intermediate layer. Since there is a stress relaxation effect, it is possible to flatten the upper surface of the intermediate layer, which is the surface on the counter electrode layer side, and prioritize the ease of stacking the counter electrode layer over the stress relaxation effect. It is preferable because the layer can be easily formed, and an electrochemical element excellent in reliability, durability and performance can be obtained.

In the present invention, the intermediate layer is formed in contact with the counter electrode layer, when the direction perpendicular to the electrolyte layer is the height direction, on the surface of the intermediate layer on the counter electrode layer side. When the maximum value of the width in the height direction of the intermediate layer upper side surface is configured to be smaller than the maximum value of the width in the height direction of the concavo-convex structure portion, it is easy to form the counter electrode layer, and It is preferable because an electrochemical element excellent in reliability, durability and performance can be obtained.

Further, in the present invention, the intermediate layer is formed in contact with the counter electrode layer, and the surface roughness (Sa) of the intermediate layer upper side surface, which is the surface of the intermediate layer on the counter electrode layer side, is 0. When the thickness is less than 0.3 μm, the counter electrode layer can be easily formed, and an electrochemical element excellent in reliability, durability and performance can be obtained, which is preferable. The surface roughness (Sa) in the present application is a value in the range of 10 μm square.

In the present invention, when the variation width of the sum of the thicknesses of the electrolyte layer and the intermediate layer is 2 μm or less within the in-plane width of 20 μm, the thickness of the entire laminated portion of the electrolyte layer and the intermediate layer is Is uniform, and the thickness of the entire electrochemical device can be easily made uniform, so that a plurality of electrochemical devices can be easily laminated to form a module, which is preferable.

In the present invention, the counter electrode layer may function as a cathode. In the case of SOFC, a composite material containing an electrolyte material and a catalytic metal is often used for the anode, while a composite oxide is often used for the cathode. However, when the counter electrode layer is the cathode, Since the material composition of the electrolyte material is significantly different from that of the electrolyte material, the effect of providing the concavo-convex structure portion is large, which is preferable.

In the present invention, it is also possible to have an insertion layer arranged between the electrode layer and the electrolyte layer. It is preferable to dispose an insertion layer between the electrode layer and the electrolyte layer because the effect of relaxing various stresses in the electrochemical device becomes greater.

Another characteristic configuration of the electrochemical device according to the present invention has a metal support made of a metal, the electrode layer is formed on the metal support, and the electrolyte layer is formed with respect to the electrode layer. It is located on the side opposite to the metal support.

According to the above characteristic configuration, since the electrode layer is formed on the metal support and the electrolyte layer is arranged on the side opposite to the metal support with respect to the electrode layer, the electrode layer, the electrolyte layer and the counter electrode layer are Since it is supported by the metal support, it is possible to realize an electrochemical element having excellent workability and robustness. In addition, since an inexpensive metal is used as the support, it is possible to make expensive electrode layers, electrolyte layers, etc. into thin layers, which is a low cost that suppresses material costs and processing costs, and high performance and reliability. It is possible to realize an electrochemical device having excellent durability.

Another characteristic configuration of the electrochemical element according to the present invention is that the electrode layer is formed on one surface of the metal support, and the metal support has a through hole penetrating from one surface to the other surface. There is a point.

According to the above characteristic structure, since the metal support has a through hole penetrating from one surface to the other surface, it is possible to easily supply gas from the other surface to the electrode layer through the through hole. It is suitable for an electrochemical device such as a battery that uses a gas for a reaction.

Another characteristic configuration of the electrochemical device according to the present invention is that the electrolyte layer contains stabilized zirconia.

According to the above characteristic configuration, since the electrolyte layer contains the stabilized zirconia, it is possible to realize an element capable of exhibiting high electrochemical performance even in a relatively high temperature range of, for example, 600° C. or higher, preferably 650° C. or higher.

In the present invention, it is preferable that the thickness of the electrolyte layer is 1 μm or more, since the required mechanical strength can be obtained even in an electrochemical element in which the electrolyte layer is formed as a thin layer. .. It is more preferable that the thickness of the electrolyte layer is 2 μm or more because the mechanical strength can be further increased.

Further, in the present invention, when the thickness of the electrolyte layer is configured to be 20 μm or less, it is possible to obtain an element having high electrochemical characteristics in which an increase in internal resistance of the electrolyte layer is suppressed, which is preferable. .. It is more preferable that the thickness of the electrolyte layer is 10 μm or less, because the increase in the internal resistance of the electrolyte layer can be further suppressed.

A characteristic configuration of the electrochemical module according to the present invention is that a plurality of the electrochemical elements described above are arranged in a stacked state.
According to the above characteristic configuration, since the above-mentioned electrochemical elements are arranged in a stacked state, a compact and high-performance electrochemical module excellent in strength and reliability while suppressing material costs and processing costs. Can be obtained.

A characteristic configuration of an electrochemical device according to the present invention has at least the above-mentioned electrochemical module and a reformer, and a fuel supply unit for supplying a fuel gas containing a reducing component to the electrochemical module, And an inverter for extracting electric power from the electrochemical module.
According to the above characteristic configuration, a fuel supply unit having an electrochemical module and a reformer for supplying a fuel gas containing a reducing component to the electrochemical module, and an inverter for extracting electric power from the electrochemical module are provided. Since it has the existing raw fuel supply infrastructure such as city gas, it is possible to extract electric power from the electrochemical module with excellent durability, reliability, and performance, and an electrochemical device with excellent durability, reliability, and performance. Can be realized. Further, since it becomes easy to construct a system for recycling the unused fuel gas discharged from the electrochemical module, it is possible to realize a highly efficient electrochemical device.

The characteristic configuration of the energy system according to the present invention is that it has the above-mentioned electrochemical device and an exhaust heat utilization unit for reusing the heat exhausted from the electrochemical device.
According to the above characteristic configuration, since the electrochemical device and the exhaust heat utilization part for reusing the heat exhausted from the electrochemical device are provided, the durability, reliability and performance are excellent, and the energy efficiency is also excellent. Energy system can be realized. It is also possible to realize a hybrid system having excellent energy efficiency by combining with a power generation system that generates power by using combustion heat of an unused fuel gas discharged from the electrochemical device.

A characteristic configuration of a solid oxide fuel cell according to the present invention for achieving the above object is to include the above-mentioned electrochemical element, and to perform the power generation reaction at a temperature of 600° C. or higher and 750° C. or lower during the rated operation. There is a point to cause.

According to the above characteristic configuration, since the power generation reaction is caused at the temperature of 600° C. or higher and 750° C. or lower during the rated operation, deterioration of the metal-supported electrochemical element is suppressed while exhibiting high power generation performance. It is possible to maintain the performance for a long time. It should be noted that, when it is possible to operate in a temperature range of 650° C. or higher and 750° C. or lower during rated operation, it is necessary to convert raw fuel into hydrogen in a fuel cell system that uses hydrocarbon gas such as city gas as raw fuel. Since it is possible to construct a system capable of covering the heat that becomes by the exhaust heat of the fuel cell, it is possible to increase the power generation efficiency of the fuel cell system, which is more preferable.

The electrochemical device manufacturing method according to the present invention for manufacturing the above-mentioned electrochemical device is characterized in that the electrolyte layer is formed by spray-coating a metal oxide powder on the electrode layer. .. Alternatively, it is characterized in that the electrolyte layer is formed by spray-coating a metal oxide powder on the insertion layer.

According to the above characteristic configuration, the concavo-convex structure portion can be formed by a simple method, and thus a low-cost electrochemical element can be obtained, which is preferable.

Schematic diagram showing the configuration of the electrochemical device Electron micrograph of cross section of electrochemical device Electron micrograph of cross section of electrochemical device Electron micrograph of cross section of electrochemical device Schematic diagram showing the configuration of an electrochemical element and an electrochemical module Schematic diagram showing the configuration of the electrochemical device and the energy system Schematic diagram showing the configuration of the electrochemical module

<First Embodiment>
Hereinafter, an electrochemical device E and a solid oxide fuel cell (SOFC) according to the present embodiment will be described with reference to FIG. 1. The electrochemical element E is used, for example, as a constituent element of a solid oxide fuel cell that is supplied with fuel gas containing hydrogen and air to generate electricity. In the following description, when expressing the positional relationship between layers, for example, the side of the counter electrode layer 6 as viewed from the electrolyte layer 4 is referred to as “upper” or “upper side”, and the side of the electrode layer 2 is referred to as “lower” or “lower side”. There is. In addition, the surface of the metal substrate 1 on which the electrode layer 2 is formed may be referred to as “front side”, and the opposite surface may be referred to as “back side”. Further, as shown in FIGS. 3 and 4, the direction perpendicular to the electrolyte layer 4 may be referred to as “height direction” or “Y direction”, and the direction orthogonal to the height direction may be referred to as “in-plane direction” or “X direction”. is there.

(Electrochemical element)
As shown in FIG. 1, the electrochemical element E includes a metal substrate 1 (metal support), an electrode layer 2 formed on the metal substrate 1, and a buffer layer 3 (formed on the electrode layer 2). An insertion layer) and an electrolyte layer 4 formed on the buffer layer 3. The electrochemical element E further has a reaction prevention layer 5 (intermediate layer) 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 preventing 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.

The electrochemical device E according to the present embodiment has a concavo-convex structure in which one or more concave portions A or convex portions B are included in the electrolyte layer upper side surface 4a (see FIG. 2) on the side of the counter electrode layer 6 in the electrolyte layer 4. A part S is formed. In the electron micrograph of the cross section of the electrochemical device E according to Example 1 (described later) in FIG. 2, the concavo-convex structure portion S1 having one concave portion A1 and one convex portion B1 is shown. The uneven structure portion S will be described later.

(Metal substrate)
The metal substrate 1 plays a role as a support for supporting the electrode layer 2, the buffer layer 3, the electrolyte layer 4 and the like and maintaining the strength of the electrochemical device E. As the material of the metal substrate 1, a material having excellent electron conductivity, heat resistance, oxidation resistance and corrosion resistance is used. For example, ferritic stainless steel, austenitic stainless steel, nickel alloy, etc. are used. Particularly, an alloy containing chromium is preferably used. In the present embodiment, the plate-shaped metal substrate 1 is used as the metal support, but other shapes such as a box shape and a cylindrical shape are also possible as the metal support.
The metal substrate 1 may have a strength sufficient to form an electrochemical element as a support, and is, for example, about 0.1 mm to 2 mm, preferably about 0.1 mm to 1 mm, more preferably about 0.1 mm. A material having a thickness of about 1 mm to 0.5 mm can be used.

The metal substrate 1 has a plurality of through holes 1a which are provided so as to penetrate the front surface and the back surface. In addition, for example, the through hole 1a can be provided in the metal substrate 1 by mechanical, chemical, or optical punching. The through hole 1a has a function of allowing gas to permeate from the back surface of the metal substrate 1 to the front surface thereof. It is also possible to use a porous metal in order to give the metal substrate 1 gas permeability. For example, the metal substrate 1 may be made of sintered metal, foam metal, or the like.

A metal oxide layer 1b as a diffusion suppressing layer is provided on the surface of the metal substrate 1. That is, the diffusion suppressing layer is formed between the metal substrate 1 and the electrode layer 2 described later. The metal oxide layer 1b is provided not only on the surface exposed to the outside of the metal substrate 1, but also on the contact surface (interface) with the electrode layer 2 and the inner surface of the through hole 1a. The metal oxide layer 1b can suppress mutual diffusion of elements between the metal substrate 1 and the electrode layer 2. For example, when ferritic stainless steel containing chromium is used as the metal substrate 1, the metal oxide layer 1b mainly contains chromium oxide. Then, the metal oxide layer 1b containing chromium oxide as a main component suppresses the diffusion of chromium atoms and the like of the metal substrate 1 into the electrode layer 2 and the electrolyte layer 4. The metal oxide layer 1b may have any thickness as long as it has both high diffusion prevention performance and low electric resistance. For example, it is preferably in the submicron order, and more specifically, it is more preferable that the average thickness is 0.3 μm or more and 0.7 μm or less. More preferably, 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.
The metal oxide layer 1b can be formed by various methods, but a method of oxidizing the surface of the metal substrate 1 to form a metal oxide is preferably used. Further, the metal oxide layer 1b may be formed on the surface of the metal substrate 1 by a sputtering method, a PLD method, a CVD method, a spray coating method, or the like, or may be formed by plating and oxidation treatment. Further, the metal oxide layer 1b may include a spinel phase having high conductivity.

When a ferritic stainless steel material is used as the metal substrate 1, a thermal expansion coefficient such as YSZ (yttria-stabilized zirconia) or GDC (also called gadolinium-doped ceria or CGO) used as a material for the electrode layer 2 and the electrolyte layer 4 is used. Is close. Therefore, the electrochemical device E is not easily damaged even when the temperature cycle of low temperature and high temperature is repeated. Therefore, the electrochemical device E having excellent long-term durability can be realized, which is preferable.

(Electrode layer)
As shown in FIG. 1, the electrode layer 2 can be provided as a thin layer in a region on the front surface of the metal substrate 1 that is larger than a region in which the through hole 1a is provided. In the case of forming a thin layer, the thickness thereof may be, for example, about 1 μm to 100 μm, preferably 5 μm to 50 μm. With such a thickness, it becomes possible to secure sufficient electrode performance while reducing the amount of expensive electrode layer material used and reducing costs. The entire area where the through holes 1a are provided is covered with the electrode layer 2. That is, the through hole 1a is formed inside the region of the metal substrate 1 where the electrode layer 2 is formed. In other words, all the through holes 1a are provided facing the electrode layer 2.

The electrode layer 2 material can be used, for example NiO-GDC, Ni-GDC, NiO-YSZ, Ni-YSZ, a composite material such as _{CuO-CeO 2, Cu-CeO} 2. In these examples, GDC, YSZ, CeO ₂ can be referred to as composite aggregates. The electrode layer 2 may be formed by a low temperature firing method (for example, a wet method using a firing treatment in a low temperature range where a firing treatment in a high temperature range higher than 1100° C. is not performed), a spray coating method, a sputtering method, a pulse laser deposition method, a CVD method. It is preferably formed by a method or the like. Due to these processes that can be used in a low temperature range, a good electrode layer 2 can be obtained without using baking in a high temperature range higher than 1100° C., for example. Therefore, it is preferable since the element mutual diffusion between the metal substrate 1 and the electrode layer 2 can be suppressed without damaging the metal substrate 1, and an electrochemical element having excellent durability can be realized. Furthermore, the low temperature firing method is more preferable because handling of the raw materials becomes easy.

The electrode layer 2 has a plurality of pores inside and on the surface thereof so as to have gas permeability.
That is, the electrode layer 2 is formed as a porous layer. The electrode layer 2 is formed, for example, so that its density is 30% or more and less than 80%. The size of the pores can be appropriately selected so that a smooth reaction proceeds when performing an electrochemical reaction. The denseness is the ratio of the material constituting the layer to the space, can be expressed as (1-porosity), and is equivalent to the relative density.

(Buffer layer)
As shown in FIG. 1, the buffer layer 3 (insertion layer) can be formed as a thin layer on the electrode layer 2 while covering the electrode layer 2. In the case of forming a thin layer, its thickness can be, for example, about 1 μm to 100 μm, preferably about 2 μm to 50 μm, and more preferably about 5 μm to 20 μm. With such a thickness, it is possible to reduce the amount of the expensive buffer layer material used and reduce the cost, while ensuring sufficient performance. Examples of the material of the buffer layer 3 include YSZ (yttria-stabilized zirconia), SSZ (scandium-stabilized zirconia), GDC (gadolinium-doped ceria), YDC (yttrium-doped ceria), and SDC (samarium-doped seria). Ceria) and the like can be used. In particular, ceria-based ceramics are preferably used.

The buffer layer 3 is formed by a low temperature firing method (for example, a wet method that uses a firing treatment in a low temperature range that does not perform a firing treatment in a high temperature range higher than 1100° C.), a spray coating method, a sputtering method, a pulse laser deposition method, a CVD method, etc. It is preferable to form by. By these film forming processes that can be used in a low temperature range, the buffer layer 3 can be obtained without using baking in a high temperature range higher than 1100° C., for example. Therefore, the element mutual diffusion between the metal substrate 1 and the electrode layer 2 can be suppressed without damaging the metal substrate 1, and the electrochemical element E having excellent durability can be realized.
Further, the low temperature firing method is more preferable because handling of raw materials becomes easy.

The buffer layer 3 preferably has oxygen ion (oxide ion) conductivity. Further, it is more preferable to have mixed conductivity of oxygen ions (oxide ions) and electrons. The buffer layer 3 having these properties is suitable for application to the electrochemical element E.

The buffer layer 3 preferably does not contain a catalytic metal component such as Ni or Cu. This is because it becomes difficult to obtain the desired buffer layer 3 when a catalytic metal component such as Ni or Cu is included.

(Electrolyte layer)
As shown in FIG. 1, the electrolyte layer 4 is formed as a thin layer on the buffer layer 3 while covering the electrode layer 2 and the buffer layer 3. Specifically, as shown in FIG. 1, the electrolyte layer 4 is provided over (straddling) the buffer layer 3 and the metal substrate 1. By configuring in this manner and joining the electrolyte layer 4 to the metal substrate 1, the electrochemical element as a whole can be made to have excellent robustness.

Further, as shown in FIG. 1, the electrolyte layer 4 is provided on a surface of the metal substrate 1 which is larger than a region where the through hole 1a is provided. That is, the through hole 1a is formed inside the region of the metal substrate 1 where the electrolyte layer 4 is formed.

In addition, around the electrolyte layer 4, gas leakage from the electrode layer 2 and the buffer layer 3 can be suppressed. To explain, when the electrochemical element E is used as a component of SOFC, gas is supplied from the back side of the metal substrate 1 to the electrode layer 2 through the through hole 1a during operation of SOFC. At the site where the electrolyte layer 4 is in contact with the metal substrate 1, gas leakage can be suppressed without providing another member such as a gasket. In the present embodiment, the electrolyte layer 4 covers the entire periphery of the electrode layer 2, but the electrolyte layer 4 may be provided on the upper portions of the electrode layer 2 and the buffer layer 3, and a gasket or the like may be provided around the electrolyte layer 4.

As a material of the electrolyte layer 4, YSZ (yttria-stabilized zirconia), SSZ (scandium-stabilized zirconia), GDC (gadolinium-doped ceria), YDC (yttrium-doped ceria), SDC (samarium-doped ceria) , LSGM (lanthanum gallate containing strontium/magnesium) and the like can be used. In particular, zirconia-based ceramics are preferably used. When the electrolyte layer 4 is made of zirconia-based ceramics, the operating temperature of the SOFC using the electrochemical element E can be made higher than that of the ceria-based ceramics. For example, when the electrochemical element E is used for SOFC, 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 a material of the electrolyte layer 4, and city gas, LPG, or the like is used as a raw fuel of the system. If a system configuration is used in which a hydrocarbon-based raw fuel is used as the SOFC anode gas by steam reforming, etc., a highly efficient SOFC system that uses the heat generated in the SOFC cell stack for reforming the raw fuel gas is provided. Can be built.

The electrolyte layer 4 may be formed by a low temperature firing method (for example, a wet method using a firing treatment in a low temperature range that does not perform a firing treatment in a high temperature range of 1100° C. or higher), a spray coating method, a sputtering method, a pulse laser deposition method, a CVD method, etc. It is preferable to form by. By these film forming processes that can be used in a low temperature range, a dense electrolyte layer 4 having a high airtightness and a gas barrier property can be obtained without firing at a high temperature range of 1100° C. or higher. Therefore, damage to the metal substrate 1 can be suppressed, and mutual diffusion of elements between the metal substrate 1 and the electrode layer 2 can be suppressed, so that the electrochemical device E having excellent performance and durability can be realized. Particularly, 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 the spray coating method because a dense electrolyte layer having high airtightness and gas barrier property can be easily obtained in a low temperature range.

The electrolyte layer 4 is densely configured in order to shield gas leaks of the anode gas and the 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 further preferably 98% or more. When the electrolyte layer 4 is a uniform layer, its density is preferably 95% or more, and more preferably 98% or more. Further, in the case where the electrolyte layer 4 is composed of a plurality of layers, it is preferable that at least a part of them contains a layer having a density of 98% or more (dense electrolyte layer), and 99%. It is more preferable to include the above layer (dense electrolyte layer). When such a dense electrolyte layer is included in a part of the electrolyte layer, a dense electrolyte layer having high airtightness and gas barrier property is formed even when the electrolyte layer is formed in a plurality of layers. Because it can be done easily.

(Reaction prevention layer)
The reaction prevention layer 5 (intermediate layer) can be formed in a thin layer on the electrolyte layer 4. In the case of forming a thin layer, its thickness can be, for example, about 1 μm to 100 μm, preferably about 2 μm to 50 μm, and more preferably about 5 μm to 20 μm. With such a thickness, it is possible to reduce the amount of expensive reaction preventing layer material used and reduce the cost, while ensuring sufficient performance. The material for the reaction prevention layer 5 may be any material that can prevent the reaction between the components of the electrolyte layer 4 and the components of the counter electrode layer 6. For example, a ceria-based material or the like is used. By introducing the reaction prevention layer 5 between the electrolyte layer 4 and the counter electrode layer 6, the reaction between the constituent material of the counter electrode layer 6 and the constituent material of the electrolyte layer 4 is effectively suppressed, and the electrochemical device E The long-term stability of performance can be improved. When the reaction preventing layer 5 is formed by appropriately using a method capable of forming the reaction preventing layer 5 at a processing temperature of 1100° C. or lower, damage to the metal substrate 1 is suppressed, and element mutual diffusion between the metal substrate 1 and the electrode layer 2 is suppressed. This is preferable because the electrochemical element E having excellent performance and durability can be realized. For example, a low temperature firing method, a spray coating method, a sputtering method, a pulse laser deposition method, a CVD method, or the like can be appropriately used. Particularly, 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, the low temperature firing method is more preferable because handling of the raw materials becomes easy.

(Counter electrode layer)
The counter electrode layer 6 can be formed as a thin layer on the electrolyte layer 4 or the reaction preventing layer 5. In the case of forming a thin layer, the thickness thereof may be, for example, about 1 μm to 100 μm, preferably 5 μm to 50 μm. With such a thickness, it is possible to reduce the amount of expensive counter electrode layer material used and reduce the cost while ensuring sufficient electrode performance. As a material of the counter electrode layer 6, for example, a complex oxide such as LSCF or LSM can be used. The counter electrode layer 6 composed of the above materials functions as a cathode.

The counter electrode layer 6 can be formed by appropriately using a method that can be formed at a processing temperature of 1100° C. or lower to prevent damage to the metal substrate 1 and to prevent element mutual diffusion between the metal substrate 1 and the electrode layer 2. Is preferable, and the electrochemical element E having excellent performance and durability can be realized, which is preferable. For example, a low temperature firing method, a spray coating method, a sputtering method, a pulse laser deposition method, a CVD method, or the like can be appropriately used. Particularly, 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, the low temperature firing method is more preferable because handling of the raw materials becomes easy.

(Solid oxide fuel cell)
By configuring the electrochemical device E as described above, the electrochemical device E can be used as a power generation cell of a solid oxide fuel cell. For example, fuel gas containing hydrogen is supplied to the electrode layer 2 from the back surface of the metal substrate 1 through the through holes 1a, and air is supplied to the counter electrode layer 6 which is the counter electrode of the electrode layer 2, for example, 600° C. or higher 750. Operate at temperatures below ℃. Then, in the counter electrode layer 6, oxygen O ₂ contained in air reacts with the electron e ⁻ to generate oxygen ion 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 supplied fuel gas reacts with oxygen ions O ²⁻ to generate water H ₂ O and electrons e ⁻ . By the above reaction, an electromotive force is generated between the electrode layer 2 and the counter electrode layer 6. In this case, the electrode layer 2 functions as a fuel electrode (anode) of SOFC, and the counter electrode layer 6 functions as an air electrode (cathode).

(Method for manufacturing electrochemical device)
Next, a method for manufacturing the electrochemical device E will be described.

(Step of forming electrode layer)
In the electrode layer forming step, the electrode layer 2 is formed as a thin film in a region wider than the region where the through hole 1a is provided on the front surface of the metal substrate 1. The through hole of the metal substrate 1 can be provided by laser processing or the like. As described above, the electrode layer 2 is formed by a method such as a low temperature firing method (a wet method of performing a firing treatment in a low temperature range of 1100° C. or lower), a spray coating method, a sputtering method, a pulse laser deposition method, a CVD method and the like. Can be used. Whichever method is used, it is desirable to perform the process at a temperature of 1100° C. or lower in order to suppress the deterioration of the metal substrate 1.

When the electrode layer forming step is performed by the low temperature firing method, specifically, it is performed as in the following example.
First, the material powder of the electrode layer 2 and a solvent are mixed to form a material paste, which is applied to the front surface of the metal substrate 1 and baked at 800°C to 1100°C.

(Step of forming diffusion suppressing layer)
The metal oxide layer 1b (diffusion suppressing layer) is formed on the surface of the metal substrate 1 during the firing process in the electrode layer forming step described above. If the firing step includes a firing step in which the firing atmosphere is an atmosphere with a low oxygen partial pressure, the effect of suppressing mutual diffusion of elements is high, and the resistance of the metal oxide layer 1b is high (the diffusion control is high). Layer) is formed, which is preferable. The electrode layer forming step may include a separate diffusion suppressing layer forming step, including the case of using a coating method without firing. In any case, it is desirable to carry out the treatment at a treatment temperature of 1100° C. or lower that can suppress damage to the metal substrate 1.

(Step of forming buffer layer)
In the buffer layer forming step, the buffer layer 3 is formed in a thin layer on the electrode layer 2 so as to cover the electrode layer 2. As described above, the buffer layer 3 is formed by a method such as a low temperature firing method (wet method of performing a firing treatment in a low temperature range of 1100° C. or lower), a spray coating method, a sputtering method, a pulse laser deposition method, a CVD method and the like. Can be used. Whichever method is used, it is desirable to perform the process at a temperature of 1100° C. or lower in order to suppress the deterioration of the metal substrate 1.

When the buffer layer forming step is performed by the low temperature firing method, specifically, it is performed as in the following example.
First, the material powder of the buffer layer 3 and a solvent are mixed to form a material paste, which is applied on the electrode layer 2 and baked at 800°C to 1100°C.

(Electrolyte layer forming step)
In the electrolyte layer forming step, the electrolyte layer 4 is formed as a thin layer on the buffer layer 3 while covering the electrode layer 2 and the buffer layer 3. As described above, the electrolyte layer 4 is formed by a method such as a low temperature firing method (a wet method of performing a firing treatment in a low temperature range of 1100° C. or lower), a spray coating method, a sputtering method, a pulse laser deposition method, a CVD method and the like. Can be used. Whichever method is used, it is desirable to perform the process at a temperature of 1100° C. or lower in order to suppress the deterioration of the metal substrate 1.

In order to form a fine electrolyte layer 4 which is dense and has high airtightness and gas barrier performance in a temperature range of 1100° C. or less, it is desirable to perform the electrolyte layer forming step by a spray coating method. In that case, the material of the electrolyte layer 4 is jetted toward the buffer layer 3 on the metal substrate 1 to form the electrolyte layer 4.

In order to form the above-mentioned concavo-convex structure site S, the electrolyte layer forming step may be performed as follows. For example, when the low temperature firing method by screen printing is used, printing of a paste containing the material of the electrolyte layer 4 is performed by using a screen having a surface processed in a shape corresponding to the shape of the uneven structure portion S to be formed. It is possible to form the concavo-convex structure on the surface of the printed paste layer, and then fire it at a temperature of 1100° C. or lower to form the electrolyte layer 4.
Alternatively, after printing the paste containing the material of the electrolyte layer 4 using a normal screen, the operation of mechanically removing the surface layer portion of the printed paste layer is added to form an uneven structure on the surface of the paste layer. It is also possible to form the electrolyte layer 4 by subsequently firing at a temperature of 1100° C. or lower. When the spray coating method is used, the speed at which the electrolyte raw material is jetted toward the buffer layer 3 on the metal substrate 1 is changed, the raw material concentration in the supplied film forming raw material is changed, and It is possible to form the electrolyte layer 4 by changing the displacement speed of the relative position of the metal substrate 1 or by mixing materials having different particle sizes with the electrolyte material in the film-forming raw material to be supplied. Even if the concentration of the supplied film forming raw material is not positively changed, an appropriate uneven structure portion S may be formed depending on the film forming conditions such as the characteristics of the raw material, the injection speed, the pressure, and the moving speed of the substrate. is there. In addition, whichever film forming method is adopted, it is also possible to form the uneven structure portion S on the surface of the electrolyte layer 4 by performing blasting after forming the electrolyte layer 4.

(Reaction prevention layer forming step)
In the reaction prevention layer forming step, the reaction prevention layer 5 is formed in a thin layer on the electrolyte layer 4. As described above, the reaction preventing layer 5 can be formed by a method such as a low temperature firing method, a spray coating method, a sputtering method, a pulse laser deposition method, a CVD method, or the like. Whichever method is used, it is desirable to perform the process at a temperature of 1100° C. or lower in order to suppress the deterioration of the metal substrate 1. In order to flatten the upper surface (intermediate layer upper side surface 5a) of the reaction preventive layer 5 (intermediate layer), for example, after the reaction preventive layer 5 is formed, leveling treatment, surface cutting/polishing treatment, or wet formation is performed. Pressing may be performed before post-baking.

(Counter electrode layer forming step)
In the counter electrode layer forming step, the counter electrode layer 6 is formed in a thin layer on the reaction preventing layer 5. As described above, the counter electrode layer 6 can be formed by a method such as a low temperature firing method, a spray coating method, a sputtering method, a pulse laser deposition method or a CVD method. Whichever method is used, it is desirable to perform the process at a temperature of 1100° C. or lower in order to suppress the deterioration of the metal substrate 1.

The electrochemical device E can be manufactured as described above.

In the electrochemical device E, the buffer layer 3 (insertion layer) and the reaction preventing layer 5 (intermediate layer) may be configured to include neither one or both. That is, a form in which the electrode layer 2 and the electrolyte layer 4 are formed in contact with each other or a form in which the electrolyte layer 4 and the counter electrode layer 6 are formed in contact with each other are also possible. In this case, in the manufacturing method described above, the buffer layer forming step and the reaction preventing layer forming step are omitted. Note that it is possible to add a step of forming another layer or stack a plurality of layers of the same type, but in any case, it is desirable to perform the step at a temperature of 1100° C. or lower.

(Example 1)
A metal substrate 1 was prepared by forming a plurality of through holes 1a by laser processing in a region having a radius of 2.5 mm from the center of a circular metal plate of the profiler 22APU having a thickness of 0.3 mm and a diameter of 25 mm. At this time, the through hole was provided by laser processing so that the diameter of the through hole 1a on the surface of the metal substrate 1 was about 10 to 15 μm.

Next, 60 wt% NiO powder and 40 wt% GDC powder were mixed and an organic binder and an organic solvent were added to prepare a paste. Using the paste, the electrode layer 2 was laminated in a region having a radius of 3 mm from the center of the metal substrate 1. Screen printing was used to form the electrode layer 2.

Next, the metal substrate 1 on which the electrode layer 2 was laminated was subjected to a baking treatment at 850° C. (electrode layer forming step, diffusion suppressing layer forming step).

The He leak amount of the metal substrate 1 in the state where the electrode layers 2 were laminated in this way was more than 50 mL/min·cm ² under a pressure of 0.2 MPa. From this, it is understood that the electrode layer 2 is formed as a porous layer having a low density and a low gas barrier property.

Next, an organic binder and an organic solvent were added to the fine powder of GDC to prepare a paste. The paste was used to screen-print a buffer layer 3 in a region having a radius of 5 mm from the center of the metal substrate 1 on which the electrode layer 2 was stacked.

Next, the metal substrate 1 having the buffer layer 3 laminated thereon was subjected to a baking treatment at 1050° C. (buffer layer forming step).

The thickness of the electrode layer 2 obtained in the above steps was about 10 μm, and the thickness of the buffer layer 3 was about 8 μm. Further, the He leak amount of the metal substrate 1 in the state where the electrode layer 2 and the buffer layer 3 were laminated in this way was 13.5 mL/min·cm ² under a pressure of 0.2 MPa.

Then, while changing the supply amount of the 8YSZ (yttria-stabilized zirconia) component between 0.3 g/min and 7.2 g/min, the buffer layer 3 is covered on the buffer layer 3 of the metal substrate 1. Was sprayed while moving the substrate at a scanning speed of 5 mm/sec within a range of 15 mm×15 mm to form the electrolyte layer 4 having irregularities on the surface (spray coating). At that time, the metal substrate 1 was not heated (electrolyte layer forming step).

The thickness of the electrolyte layer 4 obtained in the above steps was 5.0 to 5.7 μm. When the He leak amount of the metal substrate 1 in the state in which the electrode layer 2, the buffer layer 3, and the electrolyte layer 4 were laminated in this manner was measured under a pressure of 0.2 MPa, the He leak amount was the lower limit of detection (1.0 mL/ It was less than min.cm ² ). That is, the He leak amount in the state in which the electrolyte layer 4 was laminated was significantly smaller than the He leak amount in the state in which the buffer layer 3 was laminated, and was below the detection limit. Therefore, it was confirmed that the formed electrolyte layer 4 was dense and had high gas barrier performance and high quality.

Next, the GDC powder and the LSCF powder were mixed and an organic binder and an organic solvent were added to prepare a paste. The paste was used to form a counter electrode layer 6 on the electrolyte layer 4 by screen printing. Finally, the electrochemical device E having the counter electrode layer 6 formed thereon was fired at 900° C. (counter electrode layer forming step) to obtain an electrochemical device E.

With respect to the obtained electrochemical device E, hydrogen gas was supplied to the electrode layer 2 and air was supplied to the counter electrode layer 6, and the open circuit voltage (OCV) as a solid oxide fuel cell was measured. The result was 1.03V at 750°C.

Electron micrographs of the cross section of the electrochemical device E according to Example 1 thus obtained are shown in FIG. 2 (2500 times) and FIG. 3 (5000 times). As shown in FIGS. 2 and 3, in the electrochemical device E according to Example 1, the counter electrode layer 6 is formed in contact with the electrolyte layer upper side surface 4a of the electrolyte layer 4, and the concavo-convex structure site S has the counter electrode. Contacting layer 6. No peeling or cracking between layers was observed, and the layers were formed in a very uniform and high adhesive strength.

FIG. 3 is an image of the uneven structure portion S1 shown in FIG. 2 taken at a magnification of 5000 times. The concavo-convex structure portion S1 includes a relatively large concave portion A1, a convex portion B1, and a convex portion B2, but also includes a large number of concave portions and convex portions of various sizes.

The positional relationship between the vertices C1 and D1 of the concave portions A1 and the convex portions B1 of the concave-convex structure portion S1 will be described below. Regarding the distance between the vertex C1 and the vertex D1, the distance L1 in the in-plane direction (X direction) is 3.62 μm, and the distance H1 in the height direction (Y direction) is 0.64 μm. Then, the apex D1 is a point (P1) where the distance (L1) in the in-plane direction is within 5 μm and the height difference (H1) is 0.5 μm or more when viewed from the apex C1 of the recess A1. On the contrary, the vertex C1 is a point (P2) where the distance (L1) in the in-plane direction is within 5 μm and the height difference (H1) is 0.5 μm or more when viewed from the vertex D1 of the convex portion B1.

That is, in the electrochemical device E of Example 1, the distance (L1) in the in-plane direction from the vertex C1 of the recess A1 is within 5 μm, and the height difference (H1) from the vertex C1 of the recess A1 is The height difference (H1) between the point P1 that is 0.5 μm or more and the in-plane distance (L1) from the apex D1 of the convex portion B1 to within 5 μm, and the apex D1 of the convex portion B1. It can be said that the point P2 where is 0.5 μm or more is included in the uneven structure portion S1.

Further, as is clear from FIG. 3, in the concavo-convex structure portion S1, the vertex C1 of the concave portion A1 has the lowest height (coordinates in the height direction), and the vertex D1 of the convex portion B1 has the highest height. Therefore, the width in the height direction (Y direction) of the concavo-convex structure portion S1 is the distance H1, which is 0.64 μm. On the other hand, the thickness T1 of the electrolyte layer 4 shown in FIG. 3 is 5.02 μm. The distance H1 corresponds to 12% of the thickness T1. Therefore, in the electrochemical device E of Example 1, it can be said that the width in the height direction of the uneven structure portion is 5% or more of the thickness of the electrolyte layer 4.

(Example 2)

A metal substrate 1 was prepared by providing a plurality of through holes 1 a by laser processing in a region having a radius of 2.5 mm from the center of a circular metal plate of the profiler 22APU having a thickness of 0.3 mm and a diameter of 25 mm. At this time, the through hole was provided by laser processing so that the diameter of the through hole 1a on the surface of the metal substrate 1 was about 10 to 15 μm.

Next, 60 wt% NiO powder and 40 wt% GDC powder were mixed and an organic binder and an organic solvent were added to prepare a paste. Using the paste, the electrode layer 2 was laminated in a region having a radius of 3 mm from the center of the metal substrate 1. Screen printing was used to form the electrode layer 2.

Next, the metal substrate 1 on which the electrode layer 2 was laminated was subjected to a baking treatment at 850° C. (electrode layer forming step, diffusion suppressing layer forming step).

The He leak amount of the metal substrate 1 in the state where the electrode layers 2 were laminated in this way was more than 50 mL/min·cm ² under a pressure of 0.2 MPa. From this, it is understood that the electrode layer 2 is formed as a porous layer having a low density and a low gas barrier property.

Next, an organic binder and an organic solvent were added to the fine powder of GDC to prepare a paste. The paste was used to screen-print a buffer layer 3 in a region having a radius of 5 mm from the center of the metal substrate 1 on which the electrode layer 2 was stacked.

Next, the metal substrate 1 having the buffer layer 3 laminated thereon was subjected to a baking treatment at 1050° C. (buffer layer forming step).

The thickness of the electrode layer 2 obtained through the above steps was about 9 μm, and the thickness of the buffer layer 3 was about 8 μm. Further, the He leak amount of the metal substrate 1 in the state where the electrode layer 2 and the buffer layer 3 were laminated in this way was 7.5 mL/min·cm ² under a pressure of 0.2 MPa.

Then, while changing the supply amount of the 8YSZ (yttria-stabilized zirconia) component between 0.4 g/min and 9.3 g/min, the buffer layer 3 is covered on the buffer layer 3 of the metal substrate 1. Was sprayed while moving the substrate at a scanning speed of 5 mm/sec within a range of 15 mm×15 mm to form the electrolyte layer 4 having irregularities on the surface (spray coating). At that time, the metal substrate 1 was not heated (electrolyte layer forming step).

The thickness of the electrolyte layer 4 obtained in the above steps was 5.4 to 7.6 μm. When the He leak amount of the metal substrate 1 in the state in which the electrode layer 2, the buffer layer 3, and the electrolyte layer 4 were laminated in this manner was measured under a pressure of 0.2 MPa, the He leak amount was the lower limit of detection (1.0 mL/ It was less than min.cm ² ). That is, the He leak amount in the state in which the electrolyte layer 4 was laminated was significantly smaller than the He leak amount in the state in which the buffer layer 3 was laminated, and was below the detection limit. Therefore, it was confirmed that the formed electrolyte layer 4 was dense and had high gas barrier performance and high quality.

Next, an organic binder and an organic solvent were added to the fine powder of GDC to prepare a paste. Using the paste, a reaction preventive layer 5 was formed on the electrolyte layer 4 of the electrochemical device E by screen printing.

After that, the electrochemical element E having the reaction prevention layer 5 formed thereon is subjected to CIP molding at a pressure of 300 MPa and then subjected to a firing treatment at 1000° C. to form the reaction prevention layer 5 having a flat surface (reaction prevention Layer formation step).

Furthermore, GDC powder and LSCF powder were mixed, and an organic binder and an organic solvent were added to prepare a paste. Using the paste, the counter electrode layer 6 was formed on the reaction prevention layer 5 by screen printing. Finally, the electrochemical device E having the counter electrode layer 6 formed thereon was fired at 900° C. (counter electrode layer forming step) to obtain an electrochemical device E.

With respect to the obtained electrochemical device E, hydrogen gas was supplied to the electrode layer 2 and air was supplied to the counter electrode layer 6, and the open circuit voltage (OCV) as a solid oxide fuel cell was measured. The result was 1.1 V at 750°C. Further, an output of 0.28 W/cm ² was obtained at 750°C.

An electron micrograph of the cross section of the electrochemical device E according to Example 2 thus obtained is shown in FIG. 4 (2500 times). As shown in FIG. 4, in the electrochemical device E according to Example 2, the reaction prevention layer 5 (intermediate layer) is formed in contact with the electrolyte layer upper side surface 4a of the electrolyte layer 4, and the uneven structure portion S reacts. It is in contact with the prevention layer 5. The surface of the reaction prevention layer 5 on the counter electrode layer 6 side (the intermediate layer upper side surface 5a) is formed flat. No peeling or cracking between layers was observed, and the layers were formed in a very uniform and high adhesive strength.

As shown in FIG. 4, the concavo-convex structure portion S2 includes a relatively large concave portion A2, a concave portion A3, and a convex portion B3, but also includes a large number of concave portions and convex portions of various sizes. Be done. The concavo-convex structure portion S3 includes a relatively large concave portion A4, a concave portion A5, and a convex portion B4, but also includes a large number of concave portions and convex portions of various sizes.

The positional relationship between the vertex C2 and the point P3 of the recess A2 of the uneven structure portion S2 will be described below. The point P3 is a point on the upper right side in the figure of the vertex C2. Regarding the distance between the vertex C2 and the point P3, the distance L2 in the in-plane direction (X direction) is 3.08 μm, and the distance H2 in the height direction (Y direction) is 0.98 μm. Then, the point P3 is a point where the distance (L2) in the in-plane direction is within 5 μm and the height difference (H2) is 0.5 μm or more when viewed from the vertex C2 of the recess A2.

That is, in the electrochemical device E of Example 2, the distance (L2) in the in-plane direction from the vertex C2 of the recess A2 is within 5 μm, and the height difference (H2) from the vertex C2 of the recess A2 is It can be said that the point P3 that is 0.5 μm or more is included in the uneven structure portion S2.

Next, the positional relationship between the vertices C3 and D2 of the concave portions A3 and the convex portions B3 of the uneven structure portion S2 will be described. Regarding the distance between the vertex C3 and the vertex D2, the distance L3 in the in-plane direction (X direction) is 3.04 μm, and the distance H3 in the height direction (Y direction) is 1.36 μm. Then, the vertex D2 is a point (P5) where the distance (L3) in the in-plane direction is within 5 μm and the height difference (H3) is 0.5 μm or more when viewed from the vertex C3 of the recess A3. On the contrary, the vertex C3 is a point (P4) where the distance (L3) in the in-plane direction is within 5 μm and the height difference (H3) is 0.5 μm or more when viewed from the vertex D2 of the convex portion B3.

That is, in the electrochemical device E of Example 2, the distance (L3) in the in-plane direction from the apex C3 of the recess A3 is within 5 μm, and the height difference (H3) from the apex C3 of the recess A3 is A height difference (H3) between a point P5 that is 0.5 μm or more and a point (L3) within 5 μm in the in-plane direction from the vertex D2 of the convex portion B3, and the vertex D2 of the convex portion B3. It can be said that the point P4 where is 0.5 μm or more is included in the uneven structure portion S2.

Next, the positional relationship between the vertices C5 and D3 of the concave portions A5 and the convex portions B4 of the uneven structure portion S3 will be described. Regarding the distance between the vertex C5 and the vertex D3, the distance L4 in the in-plane direction (X direction) is 3.55 μm, and the distance H4 in the height direction (Y direction) is 0.98 μm. Then, the vertex D3 is a point (P7) where the distance (L4) in the in-plane direction is within 5 μm and the height difference (H4) is 0.5 μm or more when viewed from the vertex C5 of the recess A5. Conversely, the vertex C5 is a point (P6) where the distance (L4) in the in-plane direction is within 5 μm and the height difference (H4) is 0.5 μm or more when viewed from the vertex D3 of the convex portion B4.

That is, in the electrochemical device E of Example 2, the distance (L4) in the in-plane direction from the vertex C5 of the recess A5 is within 5 μm, and the height difference (H4) from the vertex C5 of the recess A5 is The height difference (H4) between a point P7 that is 0.5 μm or more and a point (L4) within 5 μm in the in-plane direction from the vertex D3 of the convex portion B4 and the vertex D3 of the convex portion B4. It can be said that the point P6 where is 0.5 μm or more is included in the uneven structure portion S3.

Of the distances H2, H3, and H4 in the height direction between the points shown in FIG. 4, H3 is the largest and is 1.36 μm. On the other hand, the thickness T2 of the electrolyte layer 4 shown in FIG. 4 is 6.26 μm. The distance H3 corresponds to 21% of the thickness T2. Therefore, in the electrochemical device E of Example 2, it can be said that the width in the height direction of the uneven structure portion is 5% or more of the thickness of the electrolyte layer 4.

Further, the width W in the height direction of the surface (intermediate layer upper side surface 5a) on the counter electrode layer 6 side of the reaction preventing layer 5 shown in FIG. 4 is 0.65 μm (the reaction preventing layer 5 shown in FIG. Is the maximum value of the width in the height direction of the surface of the counter electrode layer 6 side. On the other hand, the distance H3 in the height direction between the vertices C3 and D2 in the uneven structure portion S2 is 1.36 μm as described above (the maximum width in the height direction in the uneven structure portion shown in FIG. 4). Is. Therefore, in the electrochemical device E of Example 2, the maximum value (W) of the width in the height direction of the surface of the reaction prevention layer 5 on the side of the counter electrode layer 6 (the intermediate layer upper side surface 5a) is at the uneven structure portion S. It can be seen that it is smaller than the maximum value (H3) of the width in the height direction.

In the concave-convex structure portion S, the distance from the apex C of the recess A in the in-plane direction is within 5 μm, and the height difference from the apex C of the recess A is 0.5 μm or more. The fact that the distance in the in-plane direction from the apex D of the part B is within 5 μm and the height difference between the apex D of the convex part B and the apex D is 0.5 μm or more is included. This means that the part S includes a region having a steep slope. Specifically, it means that the uneven structure portion S includes a region having an inclination (=height difference/in-plane direction distance) of 10% or more. It is considered that such a steep region enhances the adhesion strength between the electrolyte layer 4 and the counter electrode layer 6, or between the electrolyte layer 4 and the reaction prevention layer 5 (intermediate layer).

Further, as is clear from FIG. 4, the total thickness of the electrolyte layer 4 and the reaction prevention layer 5 is substantially constant, and the fluctuation range of the rings of the thicknesses of both layers is W (=0. 65 μm). That is, in the electrochemical device E of Example 2, the variation width of the sum of the thicknesses of the electrolyte layer 4 and the reaction preventing layer 5 (intermediate layer) is configured to be 2 μm or less in the in-plane width of 20 μm. There is. The in-plane width means the width in the in-plane direction.

When the surface roughness (Sa) was measured by image processing with a laser microscope at 15 arbitrary points within the range of 10 μm square on the surface of the electrolyte layer of the electrochemical device produced in the same manner as in Example 2, it was 0.57 μm, 0. 0.53 μm, 0.50 μm, 0.44 μm, 0.44 μm, 0.37 μm, 0.34 μm, 0.34 μm, 0.32 μm, 0.30 μm, 0.25 μm, 0.25 μm, 0.24 μm, 0.23 μm , 0.22 μm, and the concavo-convex structure portion included 10 portions having a surface roughness (Sa) of 0.3 μm or more.

When the surface roughness (Sa) was measured by image processing with a laser microscope at 15 arbitrary points in the range of 10 μm square on the surface of the intermediate layer of the electrochemical device produced in the same manner as in Example 2, it was 0.08 μm, 0. 0.09 μm, 0.09 μm, 0.09 μm, 0.10 μm, 0.10 μm, 0.10 μm, 0.10 μm, 0.11 μm, 0.13 μm, 0.14 μm, 0.15 μm, 0.17 μm, 0.20 μm , 0.28 μm, and the surface roughness (Sa) of the upper surface of the intermediate layer was less than 0.3 μm.

<Second Embodiment>
The electrochemical element E, the electrochemical module M, the electrochemical device Y, and the energy system Z according to the second embodiment will be described with reference to FIGS. 5 and 6.

In the electrochemical device E according to the second embodiment, a U-shaped member 7 is attached to the back surface of the metal substrate 1, and the metal substrate 1 and the U-shaped member 7 form a tubular support.

An electrochemical module M is configured by stacking a plurality of electrochemical elements E with the current collecting member 26 interposed therebetween. The current collecting member 26 is joined to the counter electrode layer 6 of the electrochemical device E and the U-shaped member 7 and electrically connects the both.

The electrochemical module M has a gas manifold 17, a current collecting member 26, a terminating member 27, and a current drawing portion 28. In the electrochemical devices E having a plurality of layers stacked, one open end of the tubular support is connected to the gas manifold 17, and gas is supplied from the gas manifold 17. The supplied gas flows through the inside of the tubular support, and is supplied to the electrode layer 2 through the through holes 1 a of the metal substrate 1.

An overview of the energy system Z and the electrochemical device Y is shown in FIG.
The energy system Z includes an electrochemical device Y and a heat exchanger 53 as an exhaust heat utilization unit that reuses the heat exhausted from the electrochemical device Y.
The electrochemical device Y includes an electrochemical module M, a fuel supply unit that includes a desulfurizer 31 and a reformer 34, and supplies a fuel gas containing a reducing component to the electrochemical module M, and the electrochemical module. And an inverter 38 for extracting electric power from M.

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, a storage container 40, and an electrochemical module M. Have.

The desulfurizer 31 removes (desulfurizes) the sulfur compound component contained in the hydrocarbon-based raw fuel such as city gas. When the raw fuel contains a sulfur compound, the influence of the sulfur compound on the reformer 34 or the electrochemical element E can be suppressed by providing the desulfurizer 31. The vaporizer 33 produces steam from the reforming water supplied from the reforming 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 a 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 cause an electrochemical reaction to generate electricity. The combustion unit 36 mixes the reaction exhaust gas discharged from the electrochemical module M with air to burn combustible components in the reaction exhaust gas.

The electrochemical module M has a plurality of electrochemical elements E and a gas manifold 17.
The plurality of electrochemical devices E are arranged in parallel while being electrically connected to each other, and one end (lower end) of the electrochemical device E is fixed to the gas manifold 17. The electrochemical element E electrochemically reacts the reformed gas supplied through the gas manifold 17 with the air supplied from the blower 35 to generate electric power.

The inverter 38 adjusts the output power of the electrochemical module M to the same voltage and the same frequency as the power received from the commercial system (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 unit 36 are housed in a housing container 40. Then, the reformer 34 performs the reforming process of the raw fuel using the combustion heat generated by the 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 passage 42 by the operation of the booster pump 41. The reforming water in the reforming water tank 32 is supplied to the vaporizer 33 through the reforming water supply passage 44 by the operation of the reforming water pump 43. The raw fuel supply passage 42 is joined to the reforming water supply passage 44 at a site downstream of the desulfurizer 31, and the reforming water and the raw fuel joined outside the storage container 40 are stored in the storage container. It is supplied to the vaporizer 33 provided in 40.

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

The reformed gas supplied to the gas manifold 17 is distributed to the plurality of electrochemical elements E, and is supplied to the electrochemical elements E from the lower end, which is a connecting portion between the electrochemical elements E and the gas manifold 17. Mainly hydrogen (reducing component) in the reformed gas is used for the electrochemical reaction in the electrochemical device E. The reaction exhaust gas containing the residual hydrogen gas that has not been used in the reaction is discharged from the upper end of the 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 discharge port 50 to the outside of the storage container 40. A combustion catalyst unit 51 (for example, a platinum-based catalyst) is arranged 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 discharge port 50 is sent to the heat exchanger 53 through the combustion exhaust gas discharge passage 52.

The heat exchanger 53 exchanges heat between the combustion exhaust gas generated by the combustion in the combustion unit 36 and the supplied cold water to generate hot water. That is, the heat exchanger 53 operates as an exhaust heat utilization unit that reuses the heat exhausted from the electrochemical device Y.

Instead of the exhaust heat utilization unit, a reaction exhaust gas utilization unit that utilizes the reaction exhaust gas discharged from the electrochemical module M (without being combusted) may be provided. The reaction exhaust gas contains the residual hydrogen gas that has not been used in the reaction in the electrochemical device E. In the reaction exhaust gas utilization part, the remaining hydrogen gas is utilized to utilize heat by combustion and power generation by a fuel cell or the like to effectively utilize energy.

<Third Embodiment>
FIG. 7 shows another embodiment of the electrochemical module M. The electrochemical module M according to the third embodiment is formed by stacking the above-mentioned electrochemical element E, that is, the electrochemical element E having an uneven structure portion on the upper surface of the electrolyte layer with the inter-cell connecting member 71 interposed therebetween. , Constitutes the electrochemical module M.

The inter-cell connecting member 71 is a plate-shaped member that has conductivity and does not have gas permeability, and has grooves 72 that are orthogonal to each other on the front surface and the back surface. For the inter-cell connecting member 71, a metal such as stainless steel or a metal oxide can be used.

As shown in FIG. 7, when the electrochemical device E is stacked with the inter-cell connecting member 71 interposed therebetween, gas can be supplied to the electrochemical device E through the groove 72. Specifically, one of the grooves 72 serves as the first gas flow path 72a and supplies gas to the front side of the electrochemical element E, that is, the counter electrode layer 6. The other groove 72 serves as the second gas flow path 72b, and gas is supplied to the electrode layer 2 from the back surface of the electrochemical element E, that is, the back surface of the metal substrate 1 through the through hole 1a.

When the electrochemical module M is operated as a fuel cell, oxygen is supplied to the first gas flow path 72a and hydrogen is supplied to the second gas flow path 72b. Then, the reaction as a fuel cell proceeds in the electrochemical device E, and electromotive force/current is generated. The generated electric power is extracted to the outside of the electrochemical module M from the inter-cell connecting members 71 on both ends of the stacked electrochemical elements E.

In the third embodiment, the grooves 72 that are orthogonal to each other are formed on the front surface and the back surface of the inter-cell connection member 71, but the grooves 72 that are parallel to each other are formed on the front surface and the back surface of the inter-cell connection member 71. You can also

(Other embodiments)
(1) In the above embodiment, the electrochemical device E is used in a solid oxide fuel cell, but the electrochemical device E is used in a solid oxide electrolytic cell, an oxygen sensor using solid oxide, and the like. You can also do it.

(2) In the above embodiment, the metal support type solid oxide fuel cell using the metal substrate 1 as a support is used, but in the present application, the electrode support using the electrode layer 2 or the counter electrode layer 6 as a support is used. Type solid oxide fuel cells and electrolyte-supported solid oxide fuel cells having the electrolyte layer 4 as a support. In those cases, the electrode layer 2 or the counter electrode layer 6 or the electrolyte layer 4 can be made to have a required thickness so that the function as a support can be obtained.

(3) In the above embodiments, for example, NiO-GDC as the material of the electrode layer 2, Ni-GDC, NiO- YSZ, Ni-YSZ, a composite material such as _{CuO-CeO 2, Cu-CeO} 2 used, the counter electrode As the material of the layer 6, a complex oxide such as LSCF or LSM is used. The electrochemical element E configured as described above is a solid oxide type in which hydrogen gas is supplied to the electrode layer 2 to serve as a fuel electrode (anode) and air is supplied to the counter electrode layer 6 to serve as an air electrode (cathode). It can be used as a fuel cell. It is also possible to change this configuration and configure the electrochemical element E so that the electrode layer 2 can be used as the air electrode and the counter electrode layer 6 can be used as the fuel electrode. That is, for example, a composite oxide such as LSCF or LSM is used as the material of the electrode layer 2, and NiO-GDC, Ni-GDC, NiO-YSZ, Ni-YSZ, CuO-CeO ₂ , or Cu is used as the material of the counter electrode layer 6. -A composite material such as CeO ₂ is used. In the case of the electrochemical element E configured in this way, air is supplied to the electrode layer 2 to serve as an air electrode, and hydrogen gas is supplied to the counter electrode layer 6 to serve as a fuel electrode. It can be used as a fuel cell.

Note that the configurations disclosed in the above embodiments can be applied in combination with the configurations disclosed in other embodiments as long as no contradiction occurs. Further, the embodiments disclosed in the present specification are exemplifications, and the embodiments of the present invention are not limited thereto, and can be appropriately modified within a range not departing from the object of the present invention.

It can be used as an electrochemical device and a solid oxide fuel cell.

1: Metal substrate (metal support)
1a: Through hole 2: Electrode layer 3: Buffer layer (insertion layer)
4: electrolyte layer 4a: upper surface of electrolyte layer 5: reaction preventive layer (intermediate layer)
5a: upper surface of intermediate layer 6: counter electrode layer A: concave portion B: convex portion C: vertex D: vertex E: electrochemical element M: electrochemical module S: concave-convex structure portion Y: electrochemical device Z: energy system

Characteristic configuration of the electrochemical device according to the present invention to achieve the above object, at least an electrode layer, an electrolyte layer and a counter electrode layer, the electrolyte layer, the material is a metal oxide, the electrode layer And the counter electrode layer, and at least on the electrolyte layer upper surface of the electrolyte layer on the side of the counter electrode layer in the electrolyte layer, a concave-convex structure portion including one or more recesses or protrusions is formed. And an intermediate layer disposed between the electrolyte layer and the counter electrode layer, the intermediate layer is formed in contact with the electrolyte layer upper side surface of the electrolyte layer, the uneven structure portion is the intermediate In contact with the layer, the intermediate layer is formed in contact with the counter electrode layer, when the direction perpendicular to the electrolyte layer is the height direction, the side of the counter electrode layer in the intermediate layer. The maximum value of the width in the height direction of the upper surface of the intermediate layer, which is the surface, is smaller than the maximum value of the width in the height direction of the uneven structure portion .

The inventors of the present invention have, after intensive studies, thought that, unlike the prior art, forming a concavo-convex structure portion including at least one concave portion or convex portion on the upper surface of the electrolyte layer, which is at least the counter electrode layer side in the electrolyte layer. I arrived. By configuring the electrochemical element in this way, the presence of the uneven structure portion can increase the contact area between the electrolyte layer and the counter electrode layer (or the intermediate layer), and increase the adhesion strength between the layers. High performance can be obtained while relaxing various stress and improving reliability and durability.
In particular, in an electrochemical device having a thin electrolyte layer, securing reliability and durability is a problem, and its effect is great. Further, when a thin-layer electrochemical device is formed on a metal substrate as a support, the conventional method for forming a dense electrolyte layer by high-temperature firing at about 1400° C. or higher cannot be used. Although there were major issues in securing reliability/durability and performance/strength, this method produces a great effect.

According to the above characteristic configuration, since the uneven structure portion of the electrolyte layer is in contact with the intermediate layer, it is possible to increase the adhesion strength between the electrolyte layer and the intermediate layer, relax various stresses, and improve reliability. It is preferable because high performance can be obtained while improving the durability and durability.
Here, the intermediate layer does not need to be as dense as the electrolyte layer, so that the intermediate layer can be made porous to some extent, and a stress relaxation effect may be provided to some extent between the porous counter electrode layer and the intermediate layer. Therefore, it is possible to flatten the upper surface of the intermediate layer, which is the surface on the side of the counter electrode layer, and prioritize the ease of stacking the counter electrode layer over the stress relaxation effect, which facilitates the formation of the counter electrode layer. In addition, it is preferable because an electrochemical element having excellent reliability, durability and performance can be obtained .
In the present invention, the intermediate layer is formed in contact with the counter electrode layer, when the direction perpendicular to the electrolyte layer is the height direction, on the surface of the intermediate layer on the counter electrode layer side. When the maximum value of the width in the height direction of the intermediate layer upper side surface is configured to be smaller than the maximum value of the width in the height direction of the concavo-convex structure portion, it is easy to form the counter electrode layer, and It is preferable because an electrochemical element excellent in reliability, durability and performance can be obtained.

Characteristic configuration of the electrochemical device according to the present invention to achieve the above object, at least an electrode layer, an electrolyte layer and a counter electrode layer, the electrolyte layer, the material is a metal oxide, the electrode layer And the counter electrode layer, and at least on the electrolyte layer upper surface of the electrolyte layer on the side of the counter electrode layer in the electrolyte layer, a concave-convex structure portion including one or more recesses or protrusions is formed. And an intermediate layer disposed between the electrolyte layer and the counter electrode layer, the intermediate layer is formed in contact with the electrolyte layer upper side surface of the electrolyte layer, the uneven structure portion is the intermediate The intermediate layer is formed in contact with the counter electrode layer, and the surface roughness (Sa) of the upper surface of the intermediate layer, which is the surface of the intermediate layer on the counter electrode layer side, is It is less than 0.3 μm.

The inventors of the present invention have, after intensive studies, thought that, unlike the prior art, forming a concavo-convex structure portion including at least one concave portion or convex portion on the upper surface of the electrolyte layer, which is at least the counter electrode layer side in the electrolyte layer. I arrived. By configuring the electrochemical element in this way, the presence of the uneven structure portion can increase the contact area between the electrolyte layer and the counter electrode layer (or the intermediate layer), and increase the adhesion strength between the layers. High performance can be obtained while relaxing various stress and improving reliability and durability.
In particular, in an electrochemical device having a thin electrolyte layer, securing reliability and durability is a problem, and its effect is great. Further, when a thin-layer electrochemical device is formed on a metal substrate as a support, the conventional method for forming a dense electrolyte layer by high-temperature firing at about 1400° C. or higher cannot be used. Although there were major issues in securing reliability/durability and performance/strength, this method produces a great effect.

According to the above characteristic configuration, since the uneven structure portion of the electrolyte layer is in contact with the intermediate layer, it is possible to increase the adhesion strength between the electrolyte layer and the intermediate layer, relax various stresses, and improve reliability. It is preferable because high performance can be obtained while improving the durability and durability.
Here, the intermediate layer does not need to be as dense as the electrolyte layer, so that the intermediate layer can be made porous to some extent, and a stress relaxation effect may be provided to some extent between the porous counter electrode layer and the intermediate layer. Therefore, it is possible to flatten the upper surface of the intermediate layer, which is the surface on the side of the counter electrode layer, and prioritize the ease of stacking the counter electrode layer over the stress relaxation effect, which facilitates the formation of the counter electrode layer. In addition, it is preferable because an electrochemical element having excellent reliability, durability and performance can be obtained .
Further, in the present invention, the intermediate layer is formed in contact with the counter electrode layer, and the surface roughness (Sa) of the intermediate layer upper side surface, which is the surface of the intermediate layer on the counter electrode layer side, is 0. When the thickness is less than 0.3 μm, the counter electrode layer can be easily formed, and an electrochemical element excellent in reliability, durability and performance can be obtained, which is preferable. The surface roughness (Sa) in the present application is a value in the range of 10 μm square.

Characteristic configuration of the electrochemical device according to the present invention to achieve the above object, at least an electrode layer, an electrolyte layer and a counter electrode layer, the electrolyte layer, the material is a metal oxide, the electrode layer And the counter electrode layer, and at least on the electrolyte layer upper surface of the electrolyte layer on the side of the counter electrode layer in the electrolyte layer, a concave-convex structure portion including one or more recesses or protrusions is formed. And an intermediate layer disposed between the electrolyte layer and the counter electrode layer, the intermediate layer is formed in contact with the electrolyte layer upper side surface of the electrolyte layer, the uneven structure portion is the intermediate It is in contact with the layer, and the variation width of the sum of the thicknesses of the electrolyte layer and the intermediate layer is 2 μm or less in the in-plane width of 20 μm.

The inventors of the present invention have, after intensive studies, thought that, unlike the prior art, forming a concavo-convex structure portion including at least one concave portion or convex portion on the upper surface of the electrolyte layer, which is at least the counter electrode layer side in the electrolyte layer. I arrived. By configuring the electrochemical element in this way, the presence of the uneven structure portion can increase the contact area between the electrolyte layer and the counter electrode layer (or the intermediate layer), and increase the adhesion strength between the layers. High performance can be obtained while relaxing various stress and improving reliability and durability.

In particular, in an electrochemical device having a thin electrolyte layer, securing reliability and durability is a problem, and its effect is great. Further, when a thin-layer electrochemical device is formed on a metal substrate as a support, the conventional method for forming a dense electrolyte layer by high-temperature firing at about 1400° C. or higher cannot be used. Although there were major issues in securing reliability/durability and performance/strength, this method produces a great effect.

According to the above characteristic configuration, since the uneven structure portion of the electrolyte layer is in contact with the intermediate layer, it is possible to increase the adhesion strength between the electrolyte layer and the intermediate layer, relax various stresses, and improve reliability. It is preferable because high performance can be obtained while improving the durability and durability.
Here, the intermediate layer does not need to be as dense as the electrolyte layer, so that the intermediate layer can be made porous to some extent, and a stress relaxation effect may be provided to some extent between the porous counter electrode layer and the intermediate layer. Therefore, it is possible to flatten the upper surface of the intermediate layer, which is the surface on the side of the counter electrode layer, and prioritize the ease of stacking the counter electrode layer over the stress relaxation effect, which facilitates the formation of the counter electrode layer. In addition, it is preferable because an electrochemical element having excellent reliability, durability and performance can be obtained .
In the present invention, when the variation width of the sum of the thicknesses of the electrolyte layer and the intermediate layer is 2 μm or less within the in-plane width of 20 μm, the thickness of the entire laminated portion of the electrolyte layer and the intermediate layer is Is uniform, and the thickness of the entire electrochemical device can be easily made uniform, so that a plurality of electrochemical devices can be easily laminated to form a module, which is preferable.

In the present invention, when the direction perpendicular to the electrolyte layer is the height direction, and the direction orthogonal to the height direction is the in-plane direction,
A point where the distance in the in-plane direction from the apex of the recess is within 5 μm, and a height difference from the apex of the recess is 0.5 μm or more;
At least one of a point where the distance in the in-plane direction from the apex of the convex portion is within 5 μm, and a height difference from the apex of the convex portion is 0.5 μm or more. When it is configured to be included in the uneven structure portion, since the uneven structure portion of the electrolyte layer comes into contact with the laminate on the electrolyte layer such as the counter electrode layer, the adhesion strength between the electrolyte layer and the counter electrode layer, etc. It is preferable since it is possible to obtain high performance while reducing the various stresses and improving reliability and durability. If the height difference from the apex of the concave portion or the height difference from the apex of the convex portion is 3 μm or less, a counter electrode layer or the like is formed on the electrolyte layer while obtaining the above effect. It is preferable that the thickness is 2 μm or less because the layered product on the electrolyte layer such as the counter electrode layer can be easily thinned and the material cost of the counter electrode layer and the like can be reduced.

Further, in the present invention, when the direction perpendicular to the electrolyte layer is the height direction, a portion where the width in the height direction of the uneven structure portion is 5% or more of the thickness of the electrolyte layer is the uneven structure portion. If it is configured to be included in, the uneven structure portion of the electrolyte layer comes into contact with the laminate on the electrolyte layer such as the counter electrode layer, so that the adhesion strength between the electrolyte layer and the counter electrode layer, etc. is increased. In addition to being able to reduce stresses and improve reliability and durability, it is possible to obtain high performance, which is preferable, and the portion having a thickness of 10% or more of the thickness of the electrolyte layer is the uneven structure. It is more preferable to be configured to be included in the part because the above-described effect can be obtained more greatly. When the width in the height direction of the uneven structure portion is 30% or less of the thickness of the electrolyte layer, it becomes easy to stack a counter electrode layer or the like on the electrolyte layer while obtaining the above effects. Therefore, it is preferable.

Further, in the present invention, when the uneven structure portion includes a portion having a surface roughness (Sa) of 0.3 μm or more, the uneven structure portion of the electrolyte layer is formed on the electrolyte layer such as the counter electrode layer. Since it comes into contact with the laminate, the adhesion strength between the electrolyte layer and the counter electrode layer, etc. can be increased, and various stresses can be relieved to improve reliability and durability while achieving high performance. It is possible because it is possible. The surface roughness (Sa) in the present application is a value in the range of 10 μm square. In addition, when the surface roughness (Sa) is 1.5 μm or less, it is easy to stack a counter electrode layer or the like on the electrolyte layer while obtaining the above effects, and it is preferable that the surface roughness (Sa) is 1 μm or less. It is more preferable because the laminate on the electrolyte layer such as the electrode layer can be easily thinned and the material cost of the counter electrode layer and the like can be reduced.

Another characteristic configuration of the electrochemical element according to the present invention is that the counter electrode layer is formed in contact with the electrolyte layer upper side surface of the electrolyte layer, and the concavo-convex structure portion is in contact with the counter electrode layer. It is in.

According to the above characteristic configuration, since the uneven structure portion of the electrolyte layer is in contact with the counter electrode layer, it is possible to increase the adhesion strength between the electrolyte layer and the counter electrode layer, and relax various stresses. It is preferable because high performance can be obtained while improving reliability and durability.

Claims (23)

At least an electrode layer, an electrolyte layer and a counter electrode layer,
The electrolyte layer, the material is a metal oxide, is disposed between the electrode layer and the counter electrode layer,
An electrochemical device having a concavo-convex structure portion including at least one concave portion or convex portion formed on at least the upper surface of the electrolyte layer on the side of the counter electrode layer in the electrolyte layer. When the direction perpendicular to the electrolyte layer is the height direction, and the direction orthogonal to the height direction is the in-plane direction,
A point where the distance in the in-plane direction from the apex of the recess is within 5 μm, and a height difference from the apex of the recess is 0.5 μm or more;
At least one of a point where the distance in the in-plane direction from the apex of the convex portion is within 5 μm, and a height difference from the apex of the convex portion is 0.5 μm or more. The electrochemical element according to claim 1, wherein is included in the uneven structure portion. When the direction perpendicular to the electrolyte layer is the height direction,
The electrochemical element according to claim 1, wherein the uneven structure portion includes a portion in which the width in the height direction of the uneven structure portion is 5% or more of the thickness of the electrolyte layer. The electrochemical device according to claim 1, wherein the uneven structure portion includes a portion having a surface roughness (Sa) of 0.3 μm or more. The electrochemical according to any one of claims 1 to 4, wherein the counter electrode layer is formed in contact with the upper surface of the electrolyte layer of the electrolyte layer, and the concavo-convex structure portion is in contact with the counter electrode layer. element. An intermediate layer disposed between the electrolyte layer and the counter electrode layer,
The electrochemical element according to any one of claims 1 to 4, wherein the intermediate layer is formed in contact with an upper surface of the electrolyte layer above the electrolyte layer, and the concavo-convex structure portion is in contact with the intermediate layer. The intermediate layer is formed in contact with the counter electrode layer,
The electrochemical element according to claim 6, wherein an upper surface of the intermediate layer, which is a surface of the intermediate layer on the side of the counter electrode layer, is flat. The intermediate layer is formed in contact with the counter electrode layer,
When the direction perpendicular to the electrolyte layer is the height direction,
The maximum value of the width in the height direction of the intermediate layer upper side surface which is the surface on the side of the counter electrode layer in the intermediate layer is smaller than the maximum value of the width in the height direction of the uneven structure portion. Electrochemical device. The intermediate layer is formed in contact with the counter electrode layer,
The electrochemical device according to claim 6, wherein a surface roughness (Sa) of an upper surface of the intermediate layer, which is a surface of the intermediate layer on the side of the counter electrode layer, is less than 0.3 μm. 7. The electrochemical device according to claim 6, wherein the variation width of the sum of the thicknesses of the electrolyte layer and the intermediate layer is 2 μm or less in the in-plane width of 20 μm. The electrochemical device according to any one of claims 1 to 10, wherein the counter electrode layer functions as a cathode. The electrochemical element according to any one of claims 1 to 11, further comprising an insertion layer disposed between the electrode layer and the electrolyte layer. A metal support having a metal as a material is provided, the electrode layer is formed on the metal support, and the electrolyte layer is disposed on the side opposite to the metal support with respect to the electrode layer. The electrochemical device according to any one of 1 to 12. The electrochemical element according to claim 13, wherein the electrode layer is formed on one surface of the metal support, and the metal support has a through hole penetrating from one surface to the other surface. The electrochemical device according to claim 1, wherein the electrolyte layer contains stabilized zirconia. The electrochemical element according to claim 1, wherein the thickness of the electrolyte layer is 1 μm or more. The electrochemical element according to claim 1, wherein the electrolyte layer has a thickness of 20 μm or less. An electrochemical module in which a plurality of the electrochemical devices according to any one of claims 1 to 17 are arranged in a stacked state. A fuel supply unit comprising at least the electrochemical module according to claim 18 and a reformer, supplying a fuel gas containing a reducing component to the electrochemical module, and an inverter for extracting electric power from the electrochemical module. And an electrochemical device having. An energy system comprising: the electrochemical device according to claim 19; and an exhaust heat utilization unit that reuses heat exhausted from the electrochemical device. A solid oxide fuel cell comprising the electrochemical element according to any one of claims 1 to 17, wherein the electrochemical element causes a power generation reaction at a temperature of 600°C or higher and 750°C or lower during rated operation. It is an electrochemical element manufacturing method which manufactures the electrochemical element of any one of Claims 1-11, Comprising: The said oxide layer is formed by spray-coating a metal oxide powder on the said electrode layer. Electrochemical device manufacturing method. It is a manufacturing method of the electrochemical device of Claim 12, Comprising: The electrochemical device manufacturing method of forming the said electrolyte layer by spray-coating a metal oxide powder on the said insertion layer.