Electrochemical elements, electrochemical modules, electrochemical devices, energy systems, solid oxide fuel cells, solid oxide electrolysis cells

Abstract

To provide an electrochemical element and the like, having high performance and durability by including a diffusion preventing layer which can suppress element diffusion from a metal support to an electrode layer and which also does not easily block gas diffusion.SOLUTION: An electrochemical element E includes: a gas-permeable metal support 1; a diffusion preventing layer 7 formed on the metal support 1; an electrode layer 2 formed on the diffusion preventing layer 7; an electrolyte layer 4 formed on the electrode layer 2; and a counter electrode layer 6 formed on the electrolyte layer 4. The diffusion preventing layer 7 includes a first diffusion preventing layer 7a having a first porosity, and a second diffusion preventing layer 7b having a second porosity higher than the first porosity.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] The solid oxide fuel cell (SOFC) of Patent Document 1 has a support, which is a porous plate made of SUS430, and a power generation cell arranged on the top of the support. The power generation cell has an anode layer, an electrolyte layer, and a cathode layer. In such a SOFC, a diffusion prevention layer is arranged between the support and the anode layer. This makes it possible to suppress diffusion of metal between the support and the anode layer. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2016-115506 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the SOFC having a diffusion prevention layer between the support and the anode layer described in Patent Document 1, Fe and Cr diffuse from the metal support to the anode layer, which may cause a decrease in performance and durability. Therefore, there is a need for new technological developments to improve the performance and durability of SOFCs having a diffusion prevention layer.

[0005] The present invention has been made in consideration of the above-mentioned problems, and an object of the present invention is to provide an electrochemical element or the like that has high performance and durability by being provided with a diffusion prevention layer that can suppress element diffusion from a metal support to an electrode layer and is less likely to hinder gas diffusion. [Means for solving the problem]

[0006] [composition] The electrochemical device according to the present invention has the following characteristic configuration: a gas permeable metal support; a diffusion prevention layer formed on the metal support; an electrode layer formed on the diffusion prevention layer; an electrolyte layer formed on the electrode layer; a counter electrode layer formed on the electrolyte layer; Equipped with the metal support has a plurality of through holes penetrating from a back surface to a front surface on the electrode layer side, The diffusion barrier layer includes a first diffusion barrier layer having a first porosity and a second diffusion barrier layer having a second porosity higher than the first porosity. fruit , the first diffusion prevention layer is disposed closer to the metal support than the second diffusion prevention layer, the first diffusion prevention layer is disposed so as not to block the plurality of through holes, The second diffusion prevention layer is disposed on the first diffusion prevention layer. It's at the point.

[0007] According to the above characteristic configuration, the diffusion prevention layer is provided between the metal support and the electrode layer. The diffusion prevention layer includes a first diffusion prevention layer and a second diffusion prevention layer having different porosities. Furthermore, the dense and thin first diffusion prevention layer is disposed closer to the metal support than the second diffusion prevention layer, and the second diffusion prevention layer is disposed on the first diffusion prevention layer. The diffusion prevention layer can suppress element diffusion between the metal support and the electrode layer, resulting in an electrochemical element with high performance and durability. For example, it can suppress elements such as manganese, chromium, and iron from the metal support diffusing into the electrode layer and poisoning the electrode layer.

[0008] As described above, the diffusion prevention layer includes a first diffusion prevention layer and a second diffusion prevention layer having different porosities. That is, the second porosity of the second diffusion prevention layer is higher than the first porosity of the first diffusion prevention layer. This second diffusion prevention layer with high porosity is less likely to impede the supply of fuel gas or oxidant gas from the metal support to the electrode layer, so that a decrease in power generation performance due to the presence of the second diffusion prevention layer can be suppressed. Furthermore, The metal support has a plurality of through holes, and the dense first diffusion prevention layer is arranged so as not to block the plurality of through holes, thereby enabling smooth supply of fuel gas, oxidant gas, etc. from the back surface of the metal support to the electrode layer side, thereby realizing a high-performance electrochemical element. As described above, by configuring the diffusion prevention layer by combining the second diffusion prevention layer with high porosity and the first diffusion prevention layer with low porosity as in the above-mentioned characteristic configuration, it is possible to suppress element diffusion between the metal support and the electrode layer and also to suppress interruption of the supply of fuel gas or oxidant gas from the metal support to the electrode layer, thereby obtaining an electrochemical element with high performance and durability.

[0009] [composition] A further characteristic feature of the electrochemical element according to the present invention is that the second diffusion prevention layer has a thickness of 0.1 μm or more and 10 μm or less.

[0010] The second diffusion prevention layer has a higher porosity than the first diffusion prevention layer and is more permeable to fuel gas or oxidant gas. By forming the second diffusion prevention layer to a thickness of 0.1 μm or more and 10 μm or less as described above, it is possible to suppress element diffusion between the metal support and the electrode layer while simultaneously supplying fuel gas or oxidant gas from the metal support to the electrode layer, thereby suppressing a decrease in power generation performance. Furthermore, the above thickness is preferable because it is possible to prevent the electrical resistance from becoming too high even when the second diffusion prevention layer is formed.

[0011] [composition] A further characteristic feature of the electrochemical device according to the present invention is that the first diffusion prevention layer has a thickness of 3 μm or less.

[0012] The first diffusion prevention layer has a lower porosity than the second diffusion prevention layer, and is easy to suppress element diffusion between the metal support and the electrode layer, but on the other hand, the permeability of the fuel gas or oxidant gas is inferior to that of the second diffusion prevention layer. As described above, by forming the first diffusion prevention layer to a thickness of 3 μm or less, excessive inhibition of the permeation of the fuel gas or oxidant gas can be suppressed, which is preferable. For example, the first diffusion prevention layer can be formed thinner than the second diffusion prevention layer. This can further suppress the first diffusion prevention layer from excessively inhibiting the permeation of the fuel gas or oxidant gas. In addition, by forming the first diffusion prevention layer to the above thickness, excessively high electrical resistance can be suppressed, which is preferable.

[0013] [composition] A further characteristic feature of the electrochemical element according to the present invention is that at least one of the first diffusion prevention layer and the second diffusion prevention layer is made of a metal oxide.

[0014] As described above, the first and second diffusion prevention layers, at least one of which is a metal oxide, can suppress element diffusion between the metal support and the electrode layer. Also, at least one of the first and second diffusion prevention layers can be produced by oxidation during a process of producing an electrochemical device by heat treatment, for example, during a process of producing a metal support, an electrode layer, etc. by heat treatment, or during a process of heat treating a structure on which a metal support, an electrode layer, etc. are formed.

[0015] [composition] A further characteristic feature of the electrochemical element according to the present invention is that the second diffusion prevention layer contains Ce.

[0016] As described above, the second diffusion prevention layer can be formed to contain Ce. Such a second diffusion prevention layer can suppress element diffusion between the metal support and the electrode layer. Furthermore, a diffusion prevention layer containing Ce can have a thermal expansion coefficient close to that of the metal support, electrode layer, electrolyte layer, etc., and is therefore preferable because it can realize an electrochemical element with high performance and durability even when subjected to repeated temperature cycles of low and high temperatures. Such a second diffusion prevention layer is preferable because it can particularly suppress the diffusion of Fe and the like from the metal support to the electrode layer.

[0017] [composition] A further characteristic feature of the electrochemical element according to the present invention is that the second diffusion prevention layer contains at least one element selected from the group consisting of Sm, Gd, and Y.

[0018] As described above, the second diffusion prevention layer can be formed to contain at least one element selected from the group consisting of Sm, Gd, and Y. This type of second diffusion prevention layer is preferable because it can suppress element diffusion between the metal support and the electrode layer while providing a high-performance electrochemical device having a highly conductive diffusion prevention layer.

[0019] [composition] A further characteristic feature of the electrochemical element according to the present invention is that the first diffusion prevention layer contains chromium oxide as a main component.

[0020] The metal support may be made of a ferritic stainless steel material containing chromium. In this case, a first diffusion prevention layer mainly composed of chromium oxide can be formed by heat treating the metal support, and such a first diffusion prevention layer can suppress the diffusion of Cr and the like of the metal support into the electrode layer and the electrolyte layer.

[0021] [composition] A further characteristic feature of the electrochemical element according to the present invention is that the metal support is made of a ferritic stainless steel material.

[0022] As in the above characteristic configuration, when the metal support is made of a ferritic stainless steel material, it is preferable because an electrochemical element that is inexpensive and has high strength can be realized.

[0023] [composition] A further characteristic feature of the electrochemical element according to the present invention is that the electrolyte layer contains zirconia-based ceramics.

[0024] According to the above characteristic configuration, since the electrolyte layer contains stabilized zirconia, it is possible to realize an electrochemical element that can exhibit high electrochemical performance even in a relatively high temperature range of, for example, 600° C. or higher, preferably 650° C. or higher.

[0031] [composition] A further characteristic feature of the electrochemical element according to the present invention is that the second porosity of the second diffusion prevention layer is 5% or more and 60% or less.

[0032] According to the above characteristic configuration, element diffusion between the metal support and the electrode layer is suppressed, and fuel gas, oxidizer gas, etc. can be smoothly supplied to the electrode layer side. The second porosity of the second diffusion prevention layer is preferably 10% or more, more preferably 15% or more, since fuel gas, oxidizer gas, etc. can be smoothly supplied to the electrode layer side. The porosity is preferably 50% or less, more preferably 40% or less, since a second diffusion prevention element with high strength can be obtained and element diffusion between the metal support and the electrode layer can be further suppressed.

[0033] [composition] A further characteristic feature of the electrochemical element according to the present invention is that the first porosity of the first diffusion prevention layer is less than 5%.

[0034] The above characteristic configuration is preferable because it is possible to sufficiently suppress element diffusion between the metal support and the electrode layer.

[0035] [composition] The electrochemical module according to the present invention is characterized in that a plurality of the above-mentioned electrochemical elements are arranged in a group.

[0036] According to the above characteristic configuration, a plurality of the above-mentioned electrochemical elements are arranged in a cluster, so that a compact, high-performance electrochemical module having excellent strength and reliability can be obtained while keeping material costs and processing costs down.

[0037] [composition] The electrochemical device according to the present invention is characterized in that it comprises at least the above-mentioned electrochemical element or the above-mentioned electrochemical module, and a fuel converter that circulates a gas containing a reducing component to the electrochemical element or the electrochemical module, or a fuel converter that converts the gas containing a reducing component generated in the electrochemical element or the electrochemical module.

[0038] According to the above characteristic configuration, the electrochemical device has an electrochemical element or an electrochemical module, and a fuel converter that circulates a gas containing a reducing component to the electrochemical element or the electrochemical module. Therefore, when the electrochemical module is operated as a fuel cell, if hydrogen is generated from natural gas or the like supplied using an existing raw fuel supply infrastructure such as city gas by a fuel converter such as a reformer and circulated to the fuel cell, an electrochemical device having an electrochemical module with excellent durability, reliability, and performance can be realized. In addition, it becomes easier to construct a system for recycling unused fuel gas discharged from the electrochemical module, so that a highly efficient electrochemical device can be realized.

[0039] Furthermore, according to the above characteristic configuration, the device has an electrochemical element or an electrochemical module, and a fuel converter that converts a gas containing a reducing component generated by the electrochemical element or the electrochemical module. Therefore, when the electrochemical module is operated as an electrolysis cell, for example, an electrochemical device can be realized in which hydrogen generated by the electrolysis reaction of water is reacted with carbon monoxide or carbon dioxide in the fuel converter to convert it into methane or the like. With such a configuration, an electrochemical device equipped with an electrochemical module that has excellent durability, reliability, and performance can be realized.

[0040] [composition] The characteristic configuration of the electrochemical device of the present invention is that it has at least the above-mentioned electrochemical element or the above-mentioned electrochemical module, and a power converter that extracts power from the electrochemical element or the electrochemical module or that supplies power to the electrochemical element or the electrochemical module.

[0041] According to the above characteristic configuration, the power converter extracts power generated by the electrochemical element or electrochemical module, or passes power to the electrochemical element or electrochemical module. As a result, the electrochemical element or electrochemical module functions as a fuel cell or an electrolysis cell. Thus, according to the above configuration, it is possible to provide an electrochemical element or the like that can improve the efficiency of converting chemical energy such as fuel into electrical energy, or converting electrical energy into chemical energy such as fuel. For example, when an inverter is used as a power converter, the electrical output obtained from an electrochemical element or electrochemical module, which has excellent durability, reliability, and performance, can be boosted or DC converted to AC by the inverter, making it easier to utilize the electrical output obtained from the electrochemical element or electrochemical module, which is preferable.

[0042] [composition] The energy system according to the present invention is characterized in that it comprises the electrochemical device described above, and a waste heat utilization section that reuses heat discharged from the electrochemical device.

[0043] According to the above characteristic configuration, since it has an electrochemical device and a waste heat utilization unit that reuses heat discharged from the electrochemical device, it is possible to realize an energy system that is excellent in durability, reliability, and performance as well as energy efficiency. Note that it is also possible to realize a hybrid system with excellent energy efficiency by combining it with a power generation system that generates power by utilizing the combustion heat of unused fuel gas discharged from the electrochemical device.

[0044] [composition] A solid oxide fuel cell according to the present invention is characterized in that it comprises the above-mentioned electrochemical element, and causes a power generation reaction in the electrochemical element.

[0045] According to the above characteristic configuration, since the power generation reaction can be performed as a solid oxide fuel cell equipped with an electrochemical element excellent in durability, reliability and performance, a highly durable and high-performance solid oxide fuel cell can be obtained. In addition, a solid oxide fuel cell that can be operated at a temperature range of 650°C or more during rated operation is more preferable because it can construct a system that can cover the heat required for converting a raw fuel into hydrogen in a fuel cell system that uses a hydrocarbon gas such as city gas as a raw fuel, and therefore can improve the power generation efficiency of the fuel cell system. In addition, a solid oxide fuel cell that is operated at a temperature range of 900°C or less during rated operation is more preferable because the effect of suppressing Cr volatilization from a metal-supported electrochemical element is enhanced, and a solid oxide fuel cell that is operated at a temperature range of 850°C or less during rated operation is even more preferable because the effect of suppressing Cr volatilization can be further enhanced.

[0046] [composition] A solid oxide electrolysis cell according to the present invention is characterized in that it includes the above-mentioned electrochemical element, and causes an electrolytic reaction in the electrochemical element.

[0047] According to the above characteristic configuration, a solid oxide electrolysis cell having an electrochemical element with excellent durability, reliability, and performance can be used to generate gas through an electrolytic reaction, so that a highly durable, high-performance solid oxide electrolysis cell can be obtained. [Brief description of the drawings]

[0048] [Figure 1] FIG. 1 is a schematic diagram showing the configuration of an electrochemical element. [Diagram 2] 3 is a photograph showing a first diffusion prevention layer and a second diffusion prevention layer according to Example 1. [Diagram 3] FIG. 2 is a schematic diagram showing the configuration of an electrochemical element and an electrochemical module. [Figure 4] FIG. 1 is a schematic diagram showing a configuration of an electrochemical device and an energy system. [Diagram 5] FIG. 2 is a schematic diagram showing a configuration of an electrochemical module. [Figure 6]FIG. 1 is a schematic diagram showing the configuration of another electrochemical device and energy system. [Figure 7] FIG. 2 is a schematic diagram showing the configuration of another electrochemical element. [Figure 8] FIG. 2 is a schematic diagram showing the configuration of another electrochemical element. [Figure 9] FIG. 2 is a schematic diagram showing the configuration of another electrochemical element. [Figure 10] 6 is a photograph showing a first diffusion prevention layer and a second diffusion prevention layer according to Example 2. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0049] First Embodiment Hereinafter, an electrochemical element E and a solid oxide fuel cell (SOFC) according to this embodiment will be described with reference to FIG. 1. The electrochemical element E is used, for example, as a component of a solid oxide fuel cell that generates electricity by receiving a supply of fuel gas containing hydrogen and air. In the following, when expressing the positional relationship between layers, for example, the side of the counter electrode layer 6 as viewed from the electrolyte layer 4 may be referred to as "upper" or "upper side", and the side of the electrode layer 2 as "lower" or "lower side". In addition, the surface of the metal support 1 on which the electrode layer 2 is formed is referred to as the front side 1a, and the opposite surface is referred to as the back side 1b.

[0050] (Electrochemical element) As shown in FIG. 1 , the electrochemical element E has a metal support 1, a diffusion prevention layer 7 including a first diffusion prevention layer 7a and a second diffusion prevention layer 7b, an electrode layer 2 formed on the diffusion prevention layer 7, an intermediate layer 3 formed on the electrode layer 2, and an electrolyte layer 4 formed on the intermediate layer 3. The electrochemical element E further has a reaction prevention layer 5 formed on the electrolyte layer 4, and a counter electrode layer 6 formed on the reaction prevention layer 5. That is, the counter electrode layer 6 is formed on the electrolyte layer 4, and the reaction prevention layer 5 is formed between the electrolyte layer 4 and the counter electrode layer 6. The electrode layer 2 is porous, and the electrolyte layer 4 is dense.

[0051] (metal support) The metal support 1 supports the diffusion prevention layer 7 (first diffusion prevention layer 7a, second diffusion prevention layer 7b), the electrode layer 2, the intermediate layer 3, the electrolyte layer 4, etc., and maintains the strength of the electrochemical element E. In other words, the metal support 1 serves as a support that supports the electrochemical element E.

[0052] As the material of the metal support 1, a material having excellent electronic conductivity, heat resistance, oxidation resistance, and corrosion resistance is used. For example, ferritic stainless steel, austenitic stainless steel, nickel-based alloy, etc. are used. In particular, an alloy containing chromium is preferably used. In this embodiment, the metal support 1 uses an Fe-Cr-based alloy containing 18% by mass or more and 25% by mass or less of Cr, but it is particularly preferable to use an Fe-Cr-based alloy containing 0.05% by mass or more of Mn, an Fe-Cr-based alloy containing 0.15% by mass or more and 1.0% by mass or less of Ti, an Fe-Cr-based alloy containing 0.15% by mass or more and 1.0% by mass or less of Zr, an Fe-Cr-based alloy containing Ti and Zr and having a total content of Ti and Zr of 0.15% by mass or more and 1.0% by mass or less, or an Fe-Cr-based alloy containing 0.10% by mass or more and 1.0% by mass or less of Cu. It is preferable that the metal support 1 be made of a ferritic stainless steel material, since this allows for the realization of an electrochemical element that is inexpensive and has high strength.

[0053] The metal support 1 is generally plate-shaped. The metal support 1 may have sufficient strength to form an electrochemical element E as a support, and the thickness is, for example, preferably 0.1 mm or more, more preferably 0.15 mm or more, and even more preferably 0.2 mm or more from the viewpoint of ensuring strength. In addition, the thickness is, for example, preferably 2 mm or less, more preferably 1 mm or less, and even more preferably 0.5 mm or less from the viewpoint of reducing costs. The metal support 1 has a surface on which the electrode layer 2 is provided as a front side surface 1a, and has a plurality of through spaces 1c penetrating from the front side surface 1a to the back side surface 1b. For example, the metal support 1 can be provided with a plurality of through holes as a plurality of through spaces 1c by mechanical, chemical or optical perforation processing such as punching, etching, or laser processing so as to penetrate the front side surface 1a and the back side surface 1b of the metal plate. This allows the fuel gas and oxidant gas to be smoothly supplied from the back side surface 1b of the metal support 1 to the electrode layer 2 side, thereby realizing a high-performance electrochemical element. The plate-like metal support 1 can also be bent and deformed into, for example, a box-like or cylindrical shape for use.

[0054] (Diffusion prevention layer) In this embodiment, the diffusion prevention layer 7 includes a first diffusion prevention layer 7a having a first porosity and a second diffusion prevention layer 7b having a second porosity higher than the first porosity. Here, the first porosity is the ratio of voids to the total volume of the first diffusion prevention layer 7a. The second porosity is the ratio of voids to the total volume of the second diffusion prevention layer 7b. In this embodiment, the first diffusion prevention layer 7a is formed on the surface of the metal support 1 and on the inner surface of the through space 1c. The second diffusion prevention layer 7b is provided on the first diffusion prevention layer 7a provided on the surface of the metal support 1, and is provided in a thin layer state in an area larger than the area of ​​the through space 1c on the surface of the metal support 1 so as to cover the area where the through space 1c is provided. In other words, the through space 1c is formed inside the area where the second diffusion prevention layer 7b is formed. In other words, all the through spaces 1c are provided facing the second diffusion prevention layer 7b.

[0055] The diffusion prevention layer 7 (first diffusion prevention layer 7a, second diffusion prevention layer 7b) can suppress element diffusion between the metal support 1 and the electrode layer 2, and can suppress a decrease in the power generation performance of the electrochemical element E. For example, it can suppress elements such as manganese, chromium, and iron from the metal support 1 diffusing to the electrode layer 2 and poisoning the electrode layer 2. Furthermore, since the diffusion prevention layer 7 of this embodiment has the second diffusion prevention layer 7b with high porosity, the diffusion of the fuel gas or oxidant gas from the metal support 1 to the electrode layer 2 is not easily hindered by the second diffusion prevention layer 7b, and a decrease in power generation performance can be suppressed.

[0056] The first porosity of the first diffusion prevention layer 7a may be less than 5%, which is preferable because this allows the element diffusion between the metal support 1 and the electrode layer 2 to be sufficiently suppressed.

[0057] The second porosity of the second diffusion prevention layer 7b can be 5% or more and 60% or less. This can suppress element diffusion between the metal support 1 and the electrode layer 2 and smoothly supply the fuel gas, oxidizer gas, etc. to the electrode layer 2 side. The second porosity of the second diffusion prevention layer 7b is preferably 10% or more, more preferably 15% or more, since it can more smoothly supply the fuel gas, oxidizer gas, etc. to the electrode layer 2 side. The second porosity is preferably 50% or less, more preferably 40% or less, since it can provide the second diffusion prevention layer 7b with high strength and can further suppress element diffusion between the metal support 1 and the electrode layer 2.

[0058] The first porosity of the first diffusion prevention layer 7a may be less than 5%, which is preferable because it allows the element diffusion between the metal support 1 and the electrode layer 2 to be sufficiently suppressed.

[0059] As described above, by configuring the diffusion prevention layer 7 by combining the second diffusion prevention layer 7b having high porosity and the first diffusion prevention layer 7a having low porosity, it is possible to suppress element diffusion between the metal support 1 and the electrode layer 2 and also to suppress interruption of the supply of fuel gas or oxidant gas from the metal support 1 to the electrode layer 2, thereby suppressing deterioration of power generation performance. This makes it possible to improve the long-term stability of the performance of the electrochemical element E.

[0060] Furthermore, by disposing the second diffusion prevention layer 7b having a high porosity between the first diffusion prevention layer 7a having a low porosity and the electrode layer 2, it is possible to suppress element diffusion between the metal support 1 and the electrode layer 2. In other words, since the dense and thin first diffusion prevention layer 7a is disposed closer to the metal support 1 than the second diffusion prevention layer 7b, element diffusion from the metal support 1 can be sufficiently suppressed, which is preferable.

[0061] In particular, as shown in FIG. 1, it is preferable that the first diffusion prevention layer 7a is formed so as not to block a plurality of through spaces 1c. In FIG. 1, the first diffusion prevention layer 7a is formed on the surface of the metal support 1 including the side of the through space 1c. The second diffusion prevention layer 7b is formed on the front side surface 1a side of the metal support 1 so as to cover the first diffusion prevention layer 7a and the front side surface 1a side of the through space 1c. Therefore, the side surface of the through space 1c along the penetration direction is covered by the first diffusion prevention layer 7a, and penetrates from the back side surface 1b to the front side surface 1a. The front side surface 1a side, which is directly above the penetration direction of the through space 1c, is covered by the second diffusion prevention layer 7b. In other words, the first diffusion prevention layer 7a is arranged so as not to block the through space 1c of the metal support 1, but the second diffusion prevention layer 7b is arranged at the upper part of the through space 1c so as to block the through space 1c.

[0062] Even in this case, the second porosity of the second diffusion prevention layer 7b is greater than the first porosity of the first diffusion prevention layer 7a, so even if the upper part of the through space 1c is blocked by the second diffusion prevention layer 7b, the fuel gas, the oxidizer gas, and the like can be supplied to the electrode layer 2 side through the through space 1c and the second diffusion prevention layer 7b. In other words, the dense first diffusion prevention layer 7a, which has a lower porosity than the second diffusion prevention layer 7b, is arranged so as not to block the through space 1c, so that the fuel gas, the oxidizer gas, and the like can be smoothly supplied from the back surface of the metal support 1 through the through space 1c to the electrode layer 2 side, thereby achieving a high-performance electrochemical element E.

[0063] The thickness of the first diffusion prevention layer 7a may be any thickness that can achieve both high diffusion prevention performance and low electrical resistance, and is, for example, 3 μm or less. The first diffusion prevention layer 7a has a lower porosity than the second diffusion prevention layer 7b, and is easy to suppress element diffusion between the metal support 1 and the electrode layer 2, but on the other hand, the permeability of the fuel gas or oxidant gas is inferior to that of the second diffusion prevention layer 7b. As described above, the first diffusion prevention layer 7a is preferably formed to a thickness of 3 μm or less, since it can suppress the inhibition of the permeation of the fuel gas or oxidant gas. For example, the first diffusion prevention layer 7a can be formed thinner than the second diffusion prevention layer 7b. This can further suppress the first diffusion prevention layer 7a from inhibiting the permeation of the fuel gas or oxidant gas. In addition, forming the first diffusion prevention layer 7a with the above thickness is preferable because it can suppress the electrical resistance from becoming too high. In addition, the thickness of the first diffusion prevention layer 7a is more preferably 2.5 μm or less, and even more preferably 2 μm or less, since it can further suppress the increase in electrical resistance.

[0064] On the other hand, the thickness of the second diffusion prevention layer 7b may be any thickness that achieves both high diffusion prevention performance and low electrical resistance and does not reduce gas diffusion, and may be, for example, 0.1 μm or more, preferably 0.5 μm or more, and more preferably 1 μm or more. With such a thickness, it is possible to ensure the suppression of element diffusion between the metal support 1 and the electrode layer 2. Furthermore, the thickness of the second diffusion prevention layer 7b may be 10 μm or less, preferably 5 μm or less, and more preferably 3 μm or less. With such a thickness, it is possible to reduce the amount of expensive materials used and reduce costs. Furthermore, with such a thickness, it is difficult to impede the supply of fuel gas or oxidant gas from the metal support 1 to the electrode layer 2, so that it is possible to suppress the deterioration of power generation performance. Furthermore, the above thickness is preferable because it is possible to suppress the electrical resistance from becoming too high even when the second diffusion prevention layer 7b is formed.

[0065] At least one of the first diffusion prevention layer 7a and the second diffusion prevention layer 7b is preferably a metal oxide. In this case, the diffusion prevention layer 7 consisting of the first diffusion prevention layer 7a and the second diffusion prevention layer 7b can suppress element diffusion between the metal support 1 and the electrode layer 2. At least one of the first diffusion prevention layer 7a and the second diffusion prevention layer 7b consisting of a metal oxide can be produced by oxidation during the process of producing the electrochemical element E by heat treatment, for example, during the process of producing the metal support 1 and the electrode layer 2 by heat treatment, or during the process of heat treating a structure on which the metal support 1 and the electrode layer 2 are formed.

[0066] In particular, the second diffusion prevention layer 7b can be formed of a ceria-based material containing Ce. Such a second diffusion prevention layer 7b can suppress element diffusion between the metal support 1 and the electrode layer 2. As materials having similar thermal expansion coefficients, ferritic stainless steel is used for the metal support 1, and GDC (gadolinium-doped ceria, also called CGO) is used for the electrode layer 2 and electrolyte layer 4. If the second diffusion prevention layer 7b contains Ce, the thermal expansion coefficients of the metal support 1, electrode layer 2, electrolyte layer 4, etc. can be made similar, and therefore an electrochemical element E with high performance and durability can be realized even when a temperature cycle of low and high temperatures is repeated, which is preferable. The second diffusion prevention layer 7b containing Ce can also be formed by heat treatment of the electrode layer 2 containing a ceria-based material. The second diffusion prevention layer 7b can also be formed using titanium oxide (TiO2), tin oxide (SnO2), zinc oxide (ZnO)-based materials, etc., which have thermal expansion coefficients relatively close to those of the metal support 1, the electrode layer 2, and the electrolyte layer 4.

[0067] Furthermore, the second diffusion prevention layer 7b can be formed so as to contain at least one element selected from the group consisting of Sm, Gd, and Y. Such second diffusion prevention layer 7b can suppress element diffusion between the metal support 1 and the electrode layer 2, while providing a high-performance electrochemical device having a highly conductive diffusion prevention layer. As described above, ferritic stainless steel may be used for the metal support 1 as a material having a similar thermal expansion coefficient. In addition to GDC, YDC (yttrium-doped ceria), SDC (samarium-doped ceria), etc. may also be used for the electrode layer 2 and electrolyte layer 4. In this case, a second diffusion prevention layer 7b containing Sm, Gd, Y, etc. can be formed by heat treating the electrode layer 2. Such a second diffusion prevention layer 7b can suppress element diffusion between the metal support 1 and the electrode layer 2.

[0068] As described above, when ferritic stainless steel is used as the metal support 1 and YSZ (yttria-stabilized zirconia) or GDC (gadolinium-doped ceria, also known as CGO) is used as the material for the electrode layer 2 and the electrolyte layer 4, the thermal expansion coefficients of these materials are close. Therefore, even if a temperature cycle of low and high temperatures is repeated, the electrochemical element E is unlikely to be damaged. This is preferable because it allows the electrochemical element E to have excellent long-term durability.

[0069] The total content of elements such as Sm, Gd and Y in second diffusion prevention layer 7b is preferably 1.0% by mass or more and 10% by mass or less.

[0070] It has been confirmed that the above-described second diffusion prevention layer 7b particularly suppresses the diffusion of Fe and the like from the metal support 1 to the electrode layer 2, and thus is preferable in that poisoning of the electrode layer 2 is suppressed.

[0071] The first diffusion prevention layer 7a can be formed as an oxide film of the metal components contained in the metal support 1 by subjecting the metal support 1 to a sintering process. The temperature of the sintering process is preferably about 1100°C or less, since the first diffusion prevention layer 7a can be formed without damaging the metal support 1. In addition, it is preferable to perform the sintering process under atmospheric conditions with a low oxygen partial pressure, since a thin film with a high element diffusion suppression effect and a good quality first diffusion prevention layer with a low resistance value can be formed. The first diffusion prevention layer 7a can also be formed by a coating method such as plating, a low-temperature sintering method (for example, a wet method using a sintering process in a low-temperature range that does not involve a sintering process in a high-temperature range higher than 1100°C), a spray coating method (such as a thermal spraying method, an aerosol deposition method, an aerosol gas deposition method, a powder jet deposition method, a particle jet deposition method, or a cold spray method), a PVD method (such as a sputtering method or a pulsed laser deposition method), or a CVD method.

[0072] The first diffusion prevention layer 7a is preferably made of a material containing chromium oxide as a main component. A ferritic stainless steel material containing chromium may be used for the metal support 1. In this case, the first diffusion prevention layer 7a containing chromium oxide as a main component can be formed by heat treating the metal support 1. Such a first diffusion prevention layer 7a can suppress the diffusion of Cr and the like of the metal support 1 into the electrode layer 2 and the electrolyte layer 4.

[0073] The second diffusion prevention layer 7b is preferably formed by a low-temperature firing method (e.g., a wet method using firing in a low-temperature range without firing in a high-temperature range higher than 1100°C), a spray coating method (thermal spraying, aerosol deposition, aerosol gas deposition, powder jet deposition, particle jet deposition, cold spray, etc.), a PVD method (sputtering, pulse laser deposition, etc.), a CVD method, etc. By using these film formation processes that can be used in a low-temperature range, the second diffusion prevention layer 7b can be obtained without firing in a high-temperature range higher than 1100°C, for example. Therefore, the element diffusion between the metal support 1 and the electrode layer 2 can be suppressed without damaging the metal support 1, and an electrochemical element E with excellent durability can be realized. In addition, the low-temperature firing method is more preferable because it makes it easier to handle the raw materials.

[0074] Furthermore, the first diffusion prevention layer 7a may be formed simultaneously with the formation of the second diffusion prevention layer 7b, which may undergo a firing step using a low-temperature firing method or the like.

[0075] (electrode layer) 1, the electrode layer 2 can be provided in the form of a thin layer on the surface of the second diffusion prevention layer 7b so as to cover the through-space 1c of the metal support 1. When the electrode layer 2 is a thin layer, the thickness can be, for example, about 1 μm to 100 μm, and preferably 5 μm to 50 μm. With such a thickness, it is possible to reduce the amount of expensive electrode layer material used to cut costs while ensuring sufficient electrode performance.

[0076] The material of the electrode layer 2 may be, for example, a composite material such as NiO-GDC, Ni-GDC, NiO-YSZ, Ni-YSZ, CuO-CeO2, or Cu-CeO2. In these examples, GDC, YSZ, and CeO2 may be called aggregates of the composite material. The electrode layer 2 is preferably formed by a low-temperature firing method (for example, a wet method using a firing process in a low-temperature range without firing in a high-temperature range higher than 1100°C), a spray coating method (such as a thermal spray method, an aerosol deposition method, an aerosol gas deposition method, a powder jet deposition method, a particle jet deposition method, or a cold spray method), a PVD method (such as a sputtering method or a pulsed laser deposition method), or a CVD method. By using these processes that can be used in a low-temperature range, a good electrode layer 2 can be obtained without firing in a high-temperature range higher than 1100°C. This is preferable because it is possible to realize an electrochemical element having excellent durability without damaging the metal support 1 and suppressing element diffusion between the metal support 1 and the electrode layer 2 in addition to suppressing element diffusion due to the presence of the diffusion prevention layer 7. Furthermore, the use of a low-temperature firing method is even more preferable because it makes it easier to handle the raw materials.

[0077] The electrode layer 2 has a plurality of pores inside and on the surface thereof to provide 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 the electrochemical reaction proceeds smoothly. Note that the density is the ratio of the space occupied by the material constituting the layer, and can be expressed as (1-porosity), and is equivalent to the relative density.

[0078] (Middle class) The intermediate layer 3 (insertion layer) can be formed in a thin layer state on the electrode layer 2 as shown in FIG. 1. When the intermediate layer 3 is a thin layer, the thickness can be, for example, about 1 μm to 100 μm, preferably about 2 μm to 50 μm, and more preferably about 4 μm to 25 μm. With such a thickness, it is possible to reduce the amount of expensive intermediate layer material used to reduce costs while ensuring sufficient performance. As the material for the intermediate layer 3, for example, YSZ (yttria-stabilized zirconia), SSZ (scandium-stabilized zirconia), GDC (gadolinium-doped ceria), YDC (yttrium-doped ceria), SDC (samarium-doped ceria), etc. can be used. In particular, ceria-based ceramics are preferably used.

[0079] The intermediate layer 3 is preferably formed by a low-temperature firing method (e.g., a wet method using firing in a low-temperature range without firing in a high-temperature range higher than 1100°C), a spray coating method (thermal spraying, aerosol deposition, aerosol gas deposition, powder jet deposition, particle jet deposition, cold spray, etc.), a PVD method (sputtering, pulse laser deposition, etc.), a CVD method, etc. By using these film formation processes that can be used in a low-temperature range, the intermediate layer 3 can be obtained without firing in a high-temperature range higher than 1100°C, for example. Therefore, the element diffusion between the metal support 1 and the electrode layer 2 can be suppressed in addition to the element diffusion suppression due to the presence of the diffusion prevention layer 7 without damaging the metal support 1, and an electrochemical element E with excellent durability can be realized. In addition, the low-temperature firing method is more preferable because it makes it easier to handle the raw materials.

[0080] The intermediate layer 3 preferably has oxygen ion (oxide ion) conductivity. It is more preferable that the intermediate layer 3 has mixed conductivity of oxygen ions (oxide ions) and electrons. The intermediate layer 3 having these properties is suitable for application to the electrochemical element E.

[0081] (electrolyte layer) 1, the electrolyte layer 4 is formed in the state of a thin layer on the intermediate layer 3. Alternatively, it may be formed in the state of a thin film having a thickness of 10 μm or less.

[0082] As the material of the electrolyte layer 4, electrolyte materials that conduct oxygen ions, such as YSZ (yttria-stabilized zirconia), SSZ (scandium-stabilized zirconia), GDC (gadolinium-doped ceria), YDC (yttrium-doped ceria), SDC (samarium-doped ceria), and LSGM (strontium-magnesium-doped lanthanum gallate), and electrolyte materials that conduct hydrogen ions, such as perovskite-type oxides, 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 ceria-based ceramics and various hydrogen ion conductive materials. For example, when electrochemical element E is used in an SOFC, a material that can exhibit high electrolyte performance even in a high temperature range of about 650°C or more, such as YSZ, is used as the material for electrolyte layer 4, a hydrocarbon-based raw fuel such as city gas or LPG is used as the raw fuel for the system, and the raw fuel is converted into SOFC anode gas by steam reforming or the like, thereby making it possible to construct a highly efficient SOFC system in which the heat generated in the SOFC cell stack is used to reform the raw fuel gas.

[0083] The electrolyte layer 4 is preferably formed by a low-temperature firing method (for example, a wet method using firing in a low-temperature range without firing in a high-temperature range exceeding 1100°C), a spray coating method (such as a thermal spray method, an aerosol deposition method, an aerosol gas deposition method, a powder jet deposition method, a particle jet deposition method, or a cold spray method), a PVD method (such as a sputtering method or a pulse laser deposition method), or a CVD method. By using these film formation processes that can be used in a low-temperature range, it is possible to obtain an electrolyte layer 4 that is dense and has high airtightness and gas barrier properties without firing in a high-temperature range exceeding 1100°C. Therefore, damage to the metal support 1 can be suppressed, and in addition to the suppression of element diffusion due to the presence of the diffusion prevention layer 7, element diffusion between the metal support 1 and the electrode layer 2 can be suppressed, thereby realizing an electrochemical element E with excellent performance and durability. In particular, it is preferable to use a low-temperature firing method or a spray coating method, since it is possible to realize a low-cost element. Furthermore, the spray coating method is more preferable because it is easy to obtain a dense electrolyte layer that has high airtightness and gas barrier properties in a low temperature range.

[0084] The electrolyte layer 4 is densely configured to block gas leakage of the anode gas and the cathode gas and to exhibit high ion conductivity. The density of the electrolyte layer 4 is preferably 90% or more, more preferably 95% or more, and even more preferably 98% or more. When the electrolyte layer 4 is a uniform layer, the density is preferably 95% or more, and more preferably 98% or more. When the electrolyte layer 4 is configured in a multi-layered form, it is preferable that at least a part of the electrolyte layer includes a layer (a dense electrolyte layer) having a density of 98% or more, and more preferably includes a layer (a dense electrolyte layer) having a density of 99% or more. When such a dense electrolyte layer is included in a part of the electrolyte layer, it is easy to form an electrolyte layer that is dense and has high airtightness and gas barrier properties, even when the electrolyte layer is configured in a multi-layered form.

[0085] (Reaction prevention layer) The reaction prevention layer 5 can be formed in a thin layer state on the electrolyte layer 4. When the reaction prevention layer 5 is a thin layer, the thickness can be, for example, about 1 μm to 100 μm, preferably about 2 μm to 50 μm, and more preferably about 3 μm to 15 μm. With such a thickness, it is possible to reduce the amount of expensive reaction prevention layer material used to reduce costs while ensuring sufficient performance. The material of 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, and for example, a ceria-based material is used. In addition, a material containing at least one element selected from the group consisting of Sm, Gd, and Y is preferably used as the material of the reaction prevention layer 5. It is preferable that the reaction prevention layer 5 contains at least one element selected from the group consisting of Sm, Gd, and Y, and the total content of these elements is 1.0 mass% or more and 10 mass% or less. By introducing the reaction prevention layer 5 between the electrolyte layer 4 and the counter electrode layer 6, the reaction between the constituent material of the counter electrode layer 6 and the constituent material of the electrolyte layer 4 is effectively suppressed, and the long-term stability of the performance of the electrochemical element E can be improved. The reaction prevention layer 5 is preferably formed by a method capable of forming the layer at a processing temperature of 1100°C or less, since it can suppress damage to the metal support 1 and also suppress element diffusion between the metal support 1 and the electrode layer 2, thereby realizing an electrochemical element E having excellent performance and durability. For example, it can be performed by appropriately using a low-temperature firing method (for example, a wet method using a firing treatment in a low-temperature range that does not involve firing treatment in a high-temperature range exceeding 1100°C), a spray coating method (a method such as a thermal spray method, an aerosol deposition method, an aerosol gas deposition method, a powder jet deposition method, a particle jet deposition method, a cold spray method, etc.), a PVD method (a sputtering method, a pulsed laser deposition method, etc.), a CVD method, etc. In particular, it is preferable to use a low-temperature firing method or a spray coating method, etc., since it can realize a low-cost element. Furthermore, the use of a low-temperature firing method is more preferable since it makes it easier to handle the raw materials.

[0086] (Counter electrode layer) The counter electrode layer 6 can be formed in a thin layer state on the electrolyte layer 4 or the reaction prevention layer 5. When the counter electrode layer 6 is formed as a thin layer, the thickness can be, for example, about 1 μm to 100 μm, preferably 5 μm to 50 μm. With such a thickness, it is possible to reduce the amount of expensive counter electrode layer material used to reduce costs while ensuring sufficient electrode performance. As the material for the counter electrode layer 6, for example, composite oxides such as LSCF and LSM, ceria-based oxides, and mixtures thereof can be used. In particular, it is preferable that the counter electrode layer 6 contains a perovskite-type oxide containing two or more elements selected from the group consisting of La, Sr, Sm, Mn, Co, and Fe. The counter electrode layer 6 formed using the above materials functions as a cathode.

[0087] In addition, the counter electrode layer 6 is preferably formed by appropriately using a method that can form the counter electrode layer 6 at a processing temperature of 1100°C or less, since damage to the metal support 1 can be suppressed, and element diffusion between the metal support 1 and the electrode layer 2 can be suppressed, and an electrochemical element E with excellent performance and durability can be realized. For example, a low-temperature firing method (for example, a wet method using a firing process in a low-temperature range that does not involve firing at a high temperature range exceeding 1100°C), a spray coating method (a method such as a thermal spraying method, an aerosol deposition method, an aerosol gas deposition method, a powder jet deposition method, a particle jet deposition method, or a cold spray method), a PDV method (a sputtering method, a pulsed laser deposition method, or the like), a CVD method, or the like can be appropriately used. In particular, the low-temperature firing method or the spray coating method is preferable because it can realize a low-cost element. Furthermore, the low-temperature firing method is even more preferable because it makes it easier to handle the raw materials.

[0088] (Solid oxide fuel cell) By configuring the electrochemical element E as described above, when the electrochemical element is made to function as a fuel cell (electrochemical power generation cell), the electrochemical element E can be used as a power generation cell of a solid oxide fuel cell that generates a power generation reaction. For example, a fuel gas containing hydrogen is passed from the rear surface of the metal support 1 through the through space 1c to the electrode layer 2, and air is passed to the counter electrode layer 6, which is the counter electrode of the electrode layer 2, and the electrochemical element E is operated at a temperature of, for example, 500°C to 900°C. In this way, oxygen O2 contained in the air is converted into electrons e in the counter electrode layer 6. - reacts with oxygen ions O 2- The oxygen ion O 2- The hydrogen H2 contained in the supplied fuel gas is converted into oxygen ions O 2- reacts with water H2O and electrons e - When an electrolyte material that conducts hydrogen ions is used for the electrolyte layer 4, hydrogen H2 contained in the fuel gas flowing through the electrode layer 2 is converted into electrons. e- releases hydrogen ions H + The hydrogen ion H + moves through the electrolyte layer 4 to the counter electrode layer 6. At the counter electrode layer 6, oxygen O2 and hydrogen ions H + , electronic e - reacts to produce water, H2O. The above reaction generates an electromotive force between the electrode layer 2 and the counter electrode layer 6. In this case, the electrode layer 2 functions as the fuel electrode (anode) of the SOFC, and the counter electrode layer 6 functions as the air electrode (cathode).

[0089] (Method of manufacturing electrochemical device) Next, a method for producing the electrochemical element E will be described.

[0090] (Diffusion prevention layer formation step) In the diffusion prevention layer forming step, a first diffusion prevention layer 7a is formed on the inner surface of the through space 1c of the metal support 1 and on the surface of the metal support 1, and a second diffusion prevention layer 7b is formed thereon. The through space 1c of the metal support 1 can be provided by laser processing or the like.

[0091] (First diffusion prevention layer formation step) The first diffusion prevention layer 7a is formed on the surface of the metal support 1 and the through-space 1c as an oxide film of the metal components contained in the metal support 1, for example, by a firing process of the metal support 1. The temperature of the firing process is preferably about 1100°C or less, since the first diffusion prevention layer 7a can be formed without damaging the metal support 1. It is preferable to perform the firing process under atmospheric conditions with a low oxygen partial pressure, since this forms a thin film of the first diffusion prevention layer 7a with a high element diffusion suppression effect and a low resistance value. It is also possible to form the first diffusion prevention layer 7a by a coating method such as plating, a low-temperature firing method (for example, a wet method using a firing process in a low-temperature range that does not include a firing process in a high-temperature range higher than 1100°C), a spray coating method (such as a thermal spray method, an aerosol deposition method, an aerosol gas deposition method, a powder jet deposition method, a particle jet deposition method, or a cold spray method), a PVD method (such as a sputtering method or a pulsed laser deposition method), or a CVD method.

[0092] (Second diffusion prevention layer formation step) In the second diffusion prevention layer step, the second diffusion prevention layer 7b is formed in a thin film state in an area wider than the area where the through space 1c is provided on the front surface of the metal support 1. The second diffusion prevention layer 7b can be formed by a method such as a low-temperature firing method (a wet method in which firing is performed in a low temperature range of 1100°C or less), a spray coating method (a method such as a thermal spray method, an aerosol deposition method, an aerosol gas deposition method, a powder jet deposition method, a particle jet deposition method, a cold spray method, etc.), a PVD method (a sputtering method, a pulsed laser deposition method, etc.), a CVD method, etc. Whichever method is used, it is preferable to perform the method at a temperature of 1100°C or less in order to suppress deterioration of the metal support 1.

[0093] When the second diffusion prevention layer forming step is performed by a low-temperature firing method, it is specifically performed as follows. First, a material powder of the second diffusion prevention layer 7b is mixed with a solvent (dispersion medium) to prepare a material paste, which is then applied to the front surface of the metal support 1. The second diffusion prevention layer 7b is then compression molded (second diffusion prevention layer smoothing step) and fired at 1100°C or lower (second diffusion prevention layer firing step). The compression molding of the second diffusion prevention layer 7b can be performed, for example, by CIP (Cold Isostatic Pressing). Pressing, cold isostatic pressing, roll pressing, RIP (Rubber The second diffusion prevention layer 7b can be formed by, for example, isostatic pressing (PSP). The second diffusion prevention layer 7b is preferably fired at a temperature of 800° C. or higher and 1100° C. or lower. The order of the second diffusion prevention layer smoothing step and the second diffusion prevention layer firing step can be reversed. When forming an electrochemical element E having the second diffusion prevention layer 7b, the second diffusion prevention layer smoothing step and the second diffusion prevention layer firing step can be omitted, or the second diffusion prevention layer smoothing step and the second diffusion prevention layer firing step can be included in the electrode layer smoothing step and the electrode layer firing step described later. The second diffusion prevention layer smoothing step can also be performed by lapping, leveling, cutting and polishing the surface, or the like.

[0094] In some cases, the first diffusion prevention layer 7a can be formed simultaneously with the formation of the second diffusion prevention layer 7b through a firing process using a low-temperature firing method, etc. The first diffusion prevention layer 7a may be formed on the surface of the metal support 1 during firing processes in the electrode layer formation step and intermediate layer formation step described below.

[0095] (Electrode layer formation step) In the electrode layer formation step, the electrode layer 2 is formed in a thin film state on the diffusion prevention layer 7. As described above, the electrode layer 2 can be formed by a low-temperature firing method (a wet method in which firing is performed in a low temperature range of 1100°C or less), a spray coating method (such as a thermal spray method, an aerosol deposition method, an aerosol gas deposition method, a powder jet deposition method, a particle jet deposition method, or a cold spray method), a PVD method (such as a sputtering method or a pulsed laser deposition method), or a CVD method. Whichever method is used, it is preferable to perform the method at a temperature of 1100°C or less in order to suppress deterioration of the metal support 1.

[0096] When the electrode layer forming step is carried out by a low-temperature firing method, the step is specifically carried out as follows. First, a material powder of the electrode layer 2 and a solvent (dispersion medium) are mixed to prepare a material paste, which is then applied to the front surface of the metal support 1. The electrode layer 2 is then compression molded (electrode layer smoothing step) and fired at 1100°C or less (electrode layer firing step). The electrode layer 2 can be compression molded by, for example, CIP (Cold Isostatic Pressing), roll pressing, RIP (Rubber Isostatic Pressing), or the like. The electrode layer is preferably fired at a temperature of 800°C or more and 1100°C or less. The order of the electrode layer smoothing step and the electrode layer firing step can also be reversed. In the case of forming an electrochemical element having an intermediate layer 3, the electrode layer smoothing step and the electrode layer firing step may be omitted, or the electrode layer smoothing step and the electrode layer firing step may be included in the intermediate layer smoothing step and the intermediate layer firing step described below. The electrode layer smoothing step may also be performed by carrying out lapping, leveling, cutting and polishing of the surface, or the like.

[0097] (Intermediate layer formation step) In the intermediate layer forming step, the intermediate layer 3 is formed in a thin layer state on the electrode layer 2 so as to cover the electrode layer 2. As described above, the intermediate layer 3 can be formed by a low-temperature firing method (a wet method in which firing is performed in a low temperature range of 1100°C or less), a spray coating method (a thermal spray method, an aerosol deposition method, an aerosol gas deposition method, a powder jet deposition method, a particle jet deposition method, a cold spray method, or the like), a PVD method (a sputtering method, a pulsed laser deposition method, or the like), a CVD method, or the like. Whichever method is used, it is preferable to perform the method at a temperature of 1100°C or less in order to suppress deterioration of the metal support 1.

[0098] When the intermediate layer forming step is carried out by a low-temperature firing method, it is specifically carried out as follows. First, the material powder of the intermediate layer 3 and a solvent (dispersion medium) are mixed to prepare a material paste, which is then applied to the front surface of the metal support 1. The intermediate layer 3 is then compression molded (intermediate layer smoothing step) and fired at 1100°C or less (intermediate layer firing step). The intermediate layer 3 can be rolled by, for example, CIP (Cold Isostatic Pressing), roll pressing, RIP (Rubber Isostatic Pressing), or the like. The intermediate layer 3 is preferably fired at a temperature of 800°C or more and 1100°C or less. At such a temperature, the intermediate layer 3 can be formed with high strength while suppressing damage and deterioration of the metal support 1. The intermediate layer 3 is more preferably fired at 1050°C or less, and even more preferably fired at 1000°C or less. This is because the electrochemical element E can be formed while suppressing damage and deterioration of the metal support 1 as the firing temperature of the intermediate layer 3 is lowered. The order of the intermediate layer smoothing step and the intermediate layer firing step can also be reversed. The intermediate layer smoothing step can also be performed by lapping, leveling, cutting and polishing the surface, or the like.

[0099] (Electrolyte layer formation step) In the electrolyte layer forming step, the electrolyte layer 4 is formed in a thin layer state on the intermediate layer 3 while covering the electrode layer 2 and the intermediate layer 3. Alternatively, the electrolyte layer 4 may be formed in a thin film state having a thickness of 10 μm or less. As described above, the electrolyte layer 4 can be formed by a low-temperature firing method (a wet method in which firing is performed in a low temperature range of 1100° C. or less), a spray coating method (a thermal spray method, an aerosol deposition method, an aerosol gas deposition method, a powder jet deposition method, a particle jet deposition method, a cold spray method, or the like), a PVD method (a sputtering method, a pulsed laser deposition method, or the like), a CVD method, or the like. In any case where any method is used, it is preferable to perform the method at a temperature of 1100° C. or less in order to suppress deterioration of the metal support 1.

[0100] In order to form a high-quality electrolyte layer 4 that is dense and has high airtightness and gas barrier properties in a temperature range of 1100° C. or less, it is desirable to perform the electrolyte layer formation step by a spray coating method. In this case, the material of the electrolyte layer 4 is sprayed toward the intermediate layer 3 on the metal support 1 to form the electrolyte layer 4.

[0101] (Reaction prevention layer formation step) In the reaction prevention layer forming step, the reaction prevention layer 5 is formed in a thin layer state on the electrolyte layer 4. As described above, the reaction prevention layer 5 can be formed by a low-temperature firing method (a wet method in which firing is performed in a low-temperature range of 1100° C. or less), a spray coating method (such as a thermal spray method, an aerosol deposition method, an aerosol gas deposition method, a powder jet deposition method, a particle jet deposition method, or a cold spray method), a PVD method (such as a sputtering method or a pulsed laser deposition method), or a CVD method. Whichever method is used, it is preferable to perform the reaction at a temperature of 1100° C. or less in order to suppress deterioration of the metal support 1. In order to flatten the upper surface of the reaction preventive layer 5, for example, a leveling treatment or a cutting / polishing treatment may be performed on the surface after the formation of the reaction preventive layer 5, or a press working may be performed after the wet formation and before firing.

[0102] (Counter electrode layer formation step) In the counter electrode layer forming step, the counter electrode layer 6 is formed in a thin layer state on the reaction prevention layer 5. As described above, the counter electrode layer 6 can be formed by a low-temperature firing method (a wet method in which firing is performed in a low temperature range of 1100°C or less), a spray coating method (a thermal spray method, an aerosol deposition method, an aerosol gas deposition method, a powder jet deposition method, a particle jet deposition method, a cold spray method, or the like), a PVD method (a sputtering method, a pulsed laser deposition method, or the like), a CVD method, or the like. In any case, it is preferable to perform the method at a temperature of 1100°C or less in order to suppress deterioration of the metal support 1.

[0103] In this manner, the electrochemical device E can be manufactured.

[0104] In the electrochemical element E, it is also possible to adopt a configuration in which either or both of the intermediate layer 3 (insertion layer) and the reaction prevention layer 5 are not provided. That is, it is also possible to adopt a configuration in which the electrode layer 2 and the electrolyte layer 4 are formed in contact with each other, or a configuration in which the electrolyte layer 4 and the counter electrode layer 6 are formed in contact with each other. In this case, the above-mentioned manufacturing method omits the intermediate layer forming step and the reaction prevention layer forming step. It is also possible to add a step of forming another layer, or to stack a plurality of layers of the same type, but in any case, it is preferable to carry out the process at a temperature of 1100°C or less.

[0105] <Examples and Comparative Examples> In Example 1, as shown in Fig. 2, a first diffusion prevention layer 7a (first porosity) and a second diffusion prevention layer 7b (second porosity>first porosity) were formed on a metal support 1. Note that CeO2 was used as the material for the second diffusion prevention layer 7b in Example 1. Thereafter, an electrode layer 2 was formed on the first diffusion prevention layer 7a and the second diffusion prevention layer 7b, and although not shown in Fig. 2, an intermediate layer 3, an electrolyte layer 4, a reaction prevention layer 5, and a counter electrode layer 6 were formed to produce an electrochemical element E of Example 1. As Example 2, as shown in Fig. 10, a first diffusion prevention layer 7a (first porosity) and a second diffusion prevention layer 7b (second porosity>first porosity) were formed on a metal support 1. Note that GDC was used as the material for the second diffusion prevention layer 7b in Example 2. Thereafter, an electrode layer 2 was formed on the first diffusion prevention layer 7a and the second diffusion prevention layer 7b, and although not shown in Fig. 10, an intermediate layer 3, an electrolyte layer 4, a reaction prevention layer 5 and a counter electrode layer 6 were formed to produce an electrochemical element E of Example 2. Meanwhile, in the comparative example, unlike Examples 1 and 2, a first diffusion prevention layer was formed on a metal support without forming a second diffusion prevention layer 7b. Then, an electrode layer, an intermediate layer, an electrolyte layer, a reaction prevention layer, and a counter electrode layer were formed on the first diffusion prevention layer to produce an electrochemical element E of the comparative example.

[0106] In the comparative example (only the first diffusion prevention layer), almost no diffusion of Cr was observed from the metal support 1 to the electrode layer 2, but diffusion of Fe was confirmed. On the other hand, in Example 1 (first diffusion prevention layer 7a+second diffusion prevention layer 7b), not only was almost no diffusion of Cr observed from the metal support 1 to the electrode layer 2, but the diffusion of Fe was suppressed more than in the comparative example. This shows that by forming the diffusion prevention layer 7 by using the second diffusion prevention layer 7b in addition to the first diffusion prevention layer 7a, the diffusion of elements from the metal support 1 to the electrode layer 2 could be further suppressed.

[0107] In addition, the performance of the electrochemical element E was evaluated for Example 1 and the comparative example. The performance was evaluated at a temperature of 750° C. and a current density of 0.4 A / cm. 2 In Example 1, no voltage drop was observed from the beginning, and the voltage after 7000 hours of power generation was 0.88 V. On the other hand, in the comparative example, a voltage drop was observed over time, and the voltage after 7000 hours of power generation was 0.85 V. This result shows that the electrochemical element E of Example 1, which has the second diffusion prevention layer 7b in addition to the first diffusion prevention layer 7a, has higher performance and durability than the electrochemical element E of the comparative example, which has only the first diffusion prevention layer 7a.

[0108] 2, the first diffusion prevention layer 7a had a thickness La of 1.0 μm, the second diffusion prevention layer 7b had a thickness Lb of 2.2 μm, and the second porosity of the second diffusion prevention layer 7b was 24.5%. 10, the first diffusion prevention layer 7a had a thickness La of 1.5 μm, the second diffusion prevention layer 7b had a thickness Lb of 2.0 μm, and the second porosity of the second diffusion prevention layer 7b was 9.6%.

[0109] <Second embodiment> An electrochemical element E, an electrochemical module M, an electrochemical device Y, and an energy system Z according to the second embodiment will be described with reference to FIGS.

[0110] As shown in FIG. 3, an electrochemical element E according to the second embodiment has a U-shaped member 9 attached to the back surface of a metal support 1, and the metal support 1 and the U-shaped member 9 form a cylindrical support.

[0111] A plurality of electrochemical elements E are stacked (assembled) with current collecting members 26 sandwiched therebetween to form an electrochemical module M. The current collecting members 26 are joined to the counter electrode layer 6 of the electrochemical element E and the U-shaped member 9, electrically connecting them together. Note that the current collecting members 26 may be omitted, and the counter electrode layer 6 of the electrochemical element E and the U-shaped member 9 may be directly and electrically connected together.

[0112] The electrochemical module M has a gas manifold 17, a current collecting member 26, a termination member, and a current drawing section. One open end of the cylindrical support of the electrochemical element E, which is stacked multiple times, is connected to the gas manifold 17 and receives a supply of gas from the gas manifold 17. The supplied gas flows through the inside of the cylindrical support and is supplied to the electrode layer 2 through the through space 1c of the metal support 1.

[0113] FIG. 4 shows an overview of an energy system Z and an electrochemical device Y. The energy system Z has an electrochemical device Y and a heat exchanger 53 as a waste heat utilization section that reuses heat discharged from the electrochemical device Y. The electrochemical device Y has an electrochemical module M, a fuel supply module, and an inverter (an example of a power converter) 38 as an output section that extracts electric power from the electrochemical module M. The fuel supply module is composed of a desulfurizer 31, a vaporizer 33, a reformer 34, etc., and has a fuel supply section that supplies a fuel gas containing a reducing component to the electrochemical module M. In this case, the reformer 102 serves as the fuel converter.

[0114] In addition, the electrochemical device Y includes a reforming water tank 32, a blower 35, a combustion section 36, a control section 39, a storage container 40, and the like.

[0115] The desulfurizer 31 removes (desulfurizes) sulfur compound components contained in hydrocarbon raw fuel such as city gas. When sulfur compounds are contained in the raw fuel, the provision of the desulfurizer 31 can suppress the effect of the sulfur compounds on the reformer 34 or the electrochemical element E. The vaporizer 33 generates steam from the reforming water supplied from the reforming water tank 32. The reformer 34 uses the steam generated by the vaporizer 33 to steam reform the raw fuel desulfurized by the desulfurizer 31, and generates a reformed gas containing hydrogen.

[0116] The electrochemical module M generates power by electrochemical reaction using the reformed gas supplied from the reformer 34 and the air supplied from the blower 35. The combustion section 36 mixes the reaction exhaust gas discharged from the electrochemical module M with air, and combusts combustible components in the reaction exhaust gas.

[0117] The electrochemical module M has a plurality of electrochemical elements E and a gas manifold 17 . The electrochemical elements E are arranged in parallel while being electrically connected to each other, and one end (lower end) of each electrochemical element E is fixed to a gas manifold 17. The electrochemical element E generates electricity by electrochemically reacting the reformed gas supplied through the gas manifold 17 with air supplied from a blower 35.

[0118] The inverter 38 adjusts the output power of the electrochemical module M to the same voltage and frequency as the power received from a commercial grid (not shown). The control unit 39 controls the operation of the electrochemical device Y and the energy system Z.

[0119] The vaporizer 33, the reformer 34, the electrochemical module M and the combustion section 36 are housed in a storage container 40. The reformer 34 uses combustion heat generated by the combustion of the reaction exhaust gas in the combustion section 36 to carry out a reforming process of the raw fuel.

[0120] The raw fuel is supplied to the desulfurizer 31 through a raw fuel supply passage 42 by the operation of a boost pump 41. The reforming water in the reforming water tank 32 is supplied to the vaporizer 33 through a reforming water supply passage 44 by the operation of a reforming water pump 43. The raw fuel supply passage 42 merges with the reforming water supply passage 44 at a location downstream of the desulfurizer 31, and the reforming water and raw fuel merged outside the storage container 40 are supplied to the vaporizer 33 provided inside the storage container 40.

[0121] The reforming water is vaporized in the vaporizer 33 to become water vapor. The raw fuel containing water vapor produced in the vaporizer 33 is supplied to the reformer 34 through a water vapor-containing raw fuel supply passage 45. The raw fuel is steam reformed in the reformer 34 to produce a reformed gas (a first gas having a reducing component) mainly composed of hydrogen gas. The reformed gas produced in the reformer 34 is supplied to the gas manifold 17 of the electrochemical module M through a reformed gas supply passage 46.

[0122] The reformed gas supplied to the gas manifold 17 is distributed to the electrochemical elements E and supplied to the electrochemical elements E from the lower end, which is the connection between the electrochemical elements E and the gas manifold 17. Mainly hydrogen (a reducing component) in the reformed gas is used for the electrochemical reaction in the electrochemical elements E. Reaction exhaust gas containing the remaining hydrogen gas not used in the reaction is discharged from the upper end of the electrochemical element E to the combustion section 36.

[0123] The reaction exhaust gas is combusted in the combustion section 36 to become combustion exhaust gas, which is discharged to the outside of the storage container 40 from the combustion exhaust gas outlet 50. A combustion catalyst section 51 (e.g., a platinum-based catalyst) is arranged in the combustion exhaust gas outlet 50, and combusts and removes reducing components such as carbon monoxide and hydrogen contained in the combustion exhaust gas. The combustion exhaust gas discharged from the combustion exhaust gas outlet 50 is sent to a heat exchanger 53 via a combustion exhaust gas exhaust path 52.

[0124] The heat exchanger 53 exchanges heat between the combustion exhaust gas generated by the combustion in the combustion section 36 and the supplied cold water to generate hot water. That is, the heat exchanger 53 operates as a waste heat utilization section that reuses the heat discharged from the electrochemical device Y.

[0125] Instead of the exhaust heat utilization section, a reaction exhaust gas utilization section may be provided that utilizes the reaction exhaust gas discharged (without being combusted) from the electrochemical module M. The reaction exhaust gas contains the remaining hydrogen gas that was not used in the reaction in the electrochemical element E. In the reaction exhaust gas utilization section, the remaining hydrogen gas is utilized for heat utilization through combustion or for power generation using a fuel cell or the like, thereby making effective use of energy.

[0126] <Third embodiment> 5 shows another embodiment of the electrochemical module M. The electrochemical module M according to the third embodiment is configured by stacking the above-mentioned electrochemical elements E with inter-cell connection members 71 sandwiched therebetween.

[0127] The inter-cell connection member 71 is a plate-like member that is conductive and has no gas permeability, and has grooves 72 formed on the front and back surfaces that are perpendicular to each other. The inter-cell connection member 71 can be made of a metal such as stainless steel or a metal oxide.

[0128] 5, when electrochemical elements E are stacked with this inter-cell connection member 71 sandwiched therebetween, gas can be supplied to the electrochemical elements E through the grooves 72. More specifically, one groove 72 serves as a first gas flow path 72a, which supplies gas to the front side of the electrochemical element E, i.e., the counter electrode layer 6. The other groove 72 serves as a second gas flow path 72b, which supplies gas from the back side of the electrochemical element E, i.e., the back surface of the metal support 1, to the electrode layer 2 through the through-space 1c.

[0129] When this 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, a reaction as a fuel cell proceeds in the electrochemical element E, and an electromotive force and an electric current are generated. The generated electric power is taken out of the electrochemical module M from the inter-cell connection members 71 on both ends of the stacked electrochemical elements E.

[0130] In the third embodiment, the grooves 72 are formed on the front and back surfaces of the inter-cell connection member 71 so as to be perpendicular to each other. However, the grooves 72 may also be formed on the front and back surfaces of the inter-cell connection member 71 so as to be parallel to each other.

[0131] (Other embodiments) (1) In the above embodiment, the electrochemical element E or the electrochemical module M is used in a solid oxide fuel cell. However, the electrochemical element E or the electrochemical module M can also be used in a solid oxide electrolysis cell, an oxygen sensor using a solid oxide, or the like. That is, in the above embodiment, a configuration capable of improving the efficiency of converting chemical energy such as fuel into electrical energy has been described. That is, in the above embodiment, the electrochemical element E and the electrochemical module M are operated as a fuel cell, hydrogen gas is circulated through the electrode layer 2, and oxygen gas is circulated through the counter electrode layer 6. Then, oxygen molecules O2 are converted into electrons e in the counter electrode layer 6. - reacts with oxygen ions O 2- The oxygen ion O 2- moves through the electrolyte layer 4 to the electrode layer 2. In the electrode layer 2, hydrogen molecules H2 are converted into oxygen ions O 2- reacts with water H2O and electrons e- The above reaction generates an electromotive force between the electrode layer 2 and the counter electrode layer 6, generating electricity.

[0132] On the other hand, when the electrochemical element E and the electrochemical module M are operated as an electrolysis cell in which an electrolysis reaction occurs, a gas containing water vapor and carbon dioxide is passed through the electrode layer 2, and a voltage is applied between the electrode layer 2 and the counter electrode layer 6. Then, electrons e - reacts with water molecules H2O and carbon dioxide molecules CO2 to produce hydrogen molecules H2, carbon monoxide CO, and oxygen ions O 2- Oxygen ion O 2- The oxygen ions O move through the electrolyte layer 4 to the counter electrode layer 6. 2- releases electrons and becomes oxygen molecules O2. Through the above reaction, water molecules H2O are electrolyzed into hydrogen H2 and oxygen O2, and when gas containing carbon dioxide molecules CO2 is circulated, it is electrolyzed into carbon monoxide CO and oxygen O2.

[0133] When gas containing water vapor and carbon dioxide molecules CO2 is circulated, a fuel converter 91 can be provided that synthesizes various compounds such as hydrocarbons from the hydrogen and carbon monoxide generated by the electrolysis in the electrochemical element E and electrochemical module M. The hydrocarbons generated by the fuel converter 91 can be circulated to the electrochemical element E and electrochemical module M by a fuel supply unit (not shown), or can be taken out of this system / device and used as a separate fuel or chemical raw material.

[0134] In the energy system shown in Fig. 6, the electrochemical module M has a plurality of electrochemical elements E, a gas manifold 17, and a gas manifold 171. The electrochemical elements E are arranged in parallel while being electrically connected to each other, and one end (lower end) of the electrochemical elements E is fixed to the gas manifold 17, and the other end (upper end) is fixed to the gas manifold 171. The gas manifold 17 at one end (lower end) of the electrochemical elements E is supplied with water vapor and carbon dioxide. Hydrogen, carbon monoxide, and the like generated by the above-mentioned reaction in the electrochemical elements E are collected by the gas manifold 171 communicating with the other end (upper end) of the electrochemical elements E. Energy efficiency can be improved by configuring heat exchanger 90 in FIG. 6 to operate as a waste heat utilization section that exchanges heat between the reaction heat generated by the reaction in fuel converter 91 and water to vaporize them, and by configuring heat exchanger 92 in FIG. 6 to operate as a waste heat utilization section that exchanges heat between the waste heat generated by electrochemical element E and water vapor and carbon dioxide to preheat them. Furthermore, the power converter 93 supplies power to the electrochemical element E. This causes the electrochemical element E to function as an electrolysis cell as described above. Thus, the above configuration makes it possible to provide the electrochemical element E etc. that can improve the efficiency of converting electrical energy into chemical energy such as fuel.

[0135] (2) In the above embodiment, the electrode layer 2 is made of a composite material such as NiO-GDC, Ni-GDC, NiO-YSZ, Ni-YSZ, CuO-CeO2, or Cu-CeO2, and the counter electrode layer 6 is made of a composite oxide such as LSCF or LSM. The electrochemical element E configured in this manner can be used as a solid oxide fuel cell by supplying hydrogen gas to the electrode layer 2 to make it a fuel electrode (anode) and supplying air to the counter electrode layer 6 to make it an air electrode (cathode). It is also possible to change this configuration and configure the electrochemical element E so that the electrode layer 2 can be made an air electrode and the counter electrode layer 6 can be made a fuel electrode. That is, the electrode layer 2 is made of a composite oxide such as LSCF or LSM, and the counter electrode layer 6 is made of a composite material such as NiO-GDC, Ni-GDC, NiO-YSZ, Ni-YSZ, CuO-CeO2, or Cu-CeO2. In the electrochemical element E configured in this manner, air can be supplied to the electrode layer 2 to make it an air electrode, and hydrogen gas can be supplied to the counter electrode layer 6 to make it a fuel electrode, so that the electrochemical element E can be used as a solid oxide fuel cell.

[0136] (3) In the above embodiment, a flat plate type or cylindrical flat plate type solid oxide fuel cell is mainly used as the electrochemical element E, but it can also be used for electrochemical elements such as a cylindrical solid oxide fuel cell.

[0137] (4) In the above embodiment, the electrochemical device Y includes an electrochemical module M including a plurality of electrochemical elements E. However, the electrochemical device Y of the above embodiment can also be applied to a configuration including one electrochemical element E.

[0138] (5) In the above embodiment, the electrochemical element E has a U-shaped member 9 attached to the back surface of the metal support 1, and the metal support 1 and the U-shaped member 9 form a cylindrical support. However, the metal support 1 and the U-shaped member 9 may be integrally formed into a cylindrical support using a single member, or the cylindrical support may be formed using three or more members. Also, the U-shaped member 9 may be omitted, and the electrode layer 2 and the like may be supported by the metal support 1.

[0139] (6) In the above embodiment, the metal support 1 is provided with a plurality of through spaces 1c, which allows gas to pass from the back side 1b to the front side 1a of the metal support 1. However, the metal support 1 may be a porous substrate made of a porous material as long as the metal support 1 is permeable to gas. The porous substrate allows gas to pass from the back side 1b to the front side 1a of the metal support 1. An electrochemical element E having a metal support 1 made of such a porous substrate will be briefly described with reference to FIG. 7. The same reference numerals are used to designate the same components as those in the above embodiment. As shown in FIG. 7 , the electrochemical element E has a metal support 1 made of a porous substrate, a first diffusion prevention layer 7a formed on the surface of the metal support 1, a second diffusion prevention layer 7b formed on the first diffusion prevention layer 7a, an electrode layer 2 formed on the second diffusion prevention layer 7b, an intermediate layer 3 formed on the electrode layer 2, an electrolyte layer 4 formed on the intermediate layer 3, a reaction prevention layer 5 formed on the electrolyte layer 4, and a counter electrode layer 6 formed on the reaction prevention layer 5. Except for the fact that the metal support 1 is a porous substrate, the structure is the same as that of the electrochemical device E of the above embodiment.

[0140] (7) In the above embodiment, as shown in FIG. 1 , the first diffusion prevention layer 7a is formed on the surface of the metal support 1 and on the inner surface of the through-space 1c, the second diffusion prevention layer 7b is formed on the first diffusion prevention layer 7a, the electrode layer 2 is formed on the second diffusion prevention layer 7b, the intermediate layer 3 is formed on the electrode layer 2, and the electrolyte layer 4 is formed on the intermediate layer 3. However, differently from this, as shown in Fig. 8, the intermediate layer 3 may be formed in a thin layer state on the electrode layer 2 in a state where it covers the second diffusion prevention layer 7b and the electrode layer 2. More specifically, as shown in Fig. 8, the intermediate layer 3 is provided across (straddling) the electrode layer 2 and the first diffusion prevention layer 7a of the metal support 1. Note that the first diffusion prevention layer 7a is formed on the surface of the metal support 1 and on the inner surface of the through-space 1c, similarly to Fig. 1. Furthermore, the electrolyte layer 4 may be formed in a thin layer state on the intermediate layer 3, covering the second diffusion prevention layer 7b, the electrode layer 2, and the intermediate layer 3. More specifically, the electrolyte layer 4 is provided across (straddling) the intermediate layer 3 and the first diffusion prevention layer 7a of the metal support 1, as shown in Fig. 8. By configuring in this way and joining the electrolyte layer 4 to the first diffusion prevention layer 7a of the metal support 1, the electrochemical element as a whole can be made to have excellent robustness.

[0141] 8, the electrolyte layer 4 is provided on the front surface of the metal support 1 in an area larger than the area in which the through space 1c is provided. In other words, the through space 1c is formed inside the area in the metal support 1 in which the electrolyte layer 4 is formed.

[0142] Around the electrolyte layer 4, gas leakage from the diffusion prevention layer 7, the electrode layer 2, and the intermediate layer 3 can be suppressed. To explain, when the electrochemical element E is used as a component of an SOFC, gas is supplied to the electrode layer 2 from the back side of the metal support 1 through the through space 1c during operation of the SOFC. In the area where the electrolyte layer 4 contacts the metal support 1, gas leakage can be suppressed without providing a separate member such as a gasket. Note that, although the electrolyte layer 4 covers the entire periphery of the electrode layer 2 in FIG. 8, a configuration in which the electrolyte layer 4 is provided on top of the electrode layer 2 and the intermediate layer 3 and a gasket or the like is provided around the periphery may also be used.

[0143] (8) In the above embodiment, the first diffusion prevention layer 7a is disposed closer to the metal support 1 than the second diffusion prevention layer 7b. However, by combining the second diffusion prevention layer 7b having a high porosity with the first diffusion prevention layer 7a having a low porosity, it is only necessary to suppress element diffusion between the metal support 1 and the electrode layer 2 and to suppress interruption of the supply of fuel gas or oxidant gas from the metal support 1 to the electrode layer 2, and therefore the second diffusion prevention layer 7b may be disposed closer to the metal support 1 than the first diffusion prevention layer 7a.

[0144] (9) In the above embodiment, the first diffusion prevention layer 7a is provided on the surface of the metal support 1 and on the inner surface of the through-space 1c. The second diffusion prevention layer 7b is provided so as to cover the first diffusion prevention layer 7a. However, differently from this, as shown in Fig. 9, a first diffusion prevention layer 7a may be provided so as to cover a region in which the through space 1c is provided on the metal support 1. That is, in Fig. 9, the first diffusion prevention layer 7a is not formed so as to cover the inner surface of the through space 1c and the entire surface of the metal support 1, but is formed so as to be disposed on the metal support 1. Then, the second diffusion prevention layer 7b is provided so as to cover the first diffusion prevention layer 7a. In this case, the first anti-diffusion layer 7a may be formed simultaneously with the second anti-diffusion layer 7b in a firing step for forming the first anti-diffusion layer 7a. The first anti-diffusion layer 7a may be formed in a firing step separate from that for the second anti-diffusion layer 7b. The first anti-diffusion layer 7a may be formed by a coating method that does not include firing. Similarly, the second anti-diffusion layer 7b may also be formed by a coating method that does not include firing.

[0145] (10) In the above embodiment, the diffusion prevention layer 7 is composed of the first diffusion prevention layer 7a having a first porosity and the second diffusion prevention layer 7b having a second porosity higher than the first porosity. However, it is sufficient that the diffusion prevention layer 7 includes at least two diffusion prevention layers having different porosities, and it may include three or more diffusion prevention layers having different porosities.

[0146] (11) In the electrochemical element E of the above embodiment, the reaction prevention layer 5 is provided, but the reaction prevention layer 5 can be omitted.

[0147] In addition, the configurations disclosed in the above embodiments can be applied in combination with configurations disclosed in other embodiments as long as no contradiction occurs. In addition, the embodiments disclosed in this specification are examples, and the present invention is not limited to these embodiments, and can be appropriately modified within the scope of the purpose of the present invention. Industrial Applicability

[0148] The present invention can be used as an electrochemical device and a solid oxide fuel cell. [Explanation of symbols]

[0149] 1: Metal support 1c: Penetration space (through hole) 2: Electrode layer 3: Middle class 4: Electrolyte layer 5: Reaction prevention layer 6: Counter electrode layer 7: Diffusion prevention layer 7a: First diffusion prevention layer 7b: Second diffusion prevention layer 91: Fuel converter 93: Power converter 100: Electrochemical device 101: Desulfurizer 102: Reformer 103:Fuel supply section E: Electrochemical element M: Electrochemical module Y: Electrochemical device Z: Energy System

Claims

1. a gas permeable metal support; a diffusion prevention layer formed on the metal support; an electrode layer formed on the diffusion prevention layer; an electrolyte layer formed on the electrode layer; a counter electrode layer formed on the electrolyte layer; Equipped with the metal support has a plurality of through holes penetrating from a back surface to a front surface on the electrode layer side, the diffusion barrier layer includes a first diffusion barrier layer having a first porosity and a second diffusion barrier layer having a second porosity higher than the first porosity, the first diffusion prevention layer is disposed closer to the metal support than the second diffusion prevention layer, the first diffusion prevention layer is disposed so as not to block the plurality of through holes, The second diffusion prevention layer is disposed on the first diffusion prevention layer.

2. 2. The electrochemical element according to claim 1, wherein the second diffusion prevention layer has a thickness of 0.1 μm or more and 10 μm or less.

3. 3. The electrochemical device according to claim 1, wherein the first diffusion prevention layer has a thickness of 3 [mu]m or less.

4. 4. The electrochemical element according to claim 1, wherein at least one of the first diffusion prevention layer and the second diffusion prevention layer is made of a metal oxide.

5. 5. The electrochemical device according to claim 1, wherein the second diffusion prevention layer contains Ce.

6. 6. The electrochemical device according to claim 1, wherein the second diffusion prevention layer contains at least one element selected from the group consisting of Sm, Gd and Y.

7. 7. The electrochemical element according to claim 1, wherein the first diffusion prevention layer is composed mainly of chromium oxide.

8. 8. The electrochemical element according to claim 1, wherein the metal support is made of a ferritic stainless steel material.

9. 9. The electrochemical element according to claim 1, wherein the electrolyte layer contains zirconia-based ceramics.

10. 10. The electrochemical element according to claim 1, wherein the second porosity of the second diffusion barrier layer is 5% or more and 60% or less.

11. 11. The electrochemical element according to claim 1, wherein the first porosity of the first diffusion prevention layer is less than 5%.

12. An electrochemical module in which a plurality of electrochemical elements according to any one of claims 1 to 11 are arranged in an assembled state.

13. The electrochemical element according to any one of claims 1 to 11 or the electrochemical module according to claim 12; an electrochemical device comprising at least a fuel converter that circulates a gas containing a reducing component to the electrochemical element or the electrochemical module, or a fuel converter that converts a gas containing a reducing component generated in the electrochemical element or the electrochemical module.

14. The electrochemical element according to any one of claims 1 to 11 or the electrochemical module according to claim 12; and a power converter that extracts power from said electrochemical element or said electrochemical module or passes power to said electrochemical element or said electrochemical module.

15. 15. An energy system comprising: the electrochemical device according to claim 13; and a waste heat utilization section that reuses heat discharged from the electrochemical device.

16. 12. A solid oxide fuel cell comprising the electrochemical element according to claim 1, wherein a power generating reaction occurs in the electrochemical element.

17. A solid oxide electrolysis cell comprising the electrochemical element according to any one of claims 1 to 11, in which an electrolytic reaction occurs in the electrochemical element.

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