Bonding materials, electrochemical modules, solid oxide fuel cells, solid oxide electrolytic cells, electrochemical devices, energy systems, and methods for manufacturing electrochemical modules.

Abstract

It enables firing at relatively low temperatures and ensures a good oxygen supply to the air electrode (or oxygen generating electrode) under operating conditions. [Solution] A bonding material 10 for bonding an electrochemical element E, in which an electrode layer 2, an electrolyte layer 4, and a counter electrode layer 6 are stacked in the order described above, and an inter-cell connecting member 26 by baking, comprising a mixture of a porous-forming resin that volatilizes at 200°C to 300°C and a metal oxide containing particulate Co-Mn.

Description

[Technical Field]

[0001] The present invention relates to a bonding material for joining an electrochemical element in which an electrode layer, an electrolyte layer, and a counter electrode layer are stacked in the order described above, and an inter-cell connecting member, an electrochemical module, a solid oxide fuel cell, a solid oxide electrolytic cell, an electrochemical device, an energy system, and a method for manufacturing an electrochemical module. [Background technology]

[0002] In solid oxide fuel cell cell stacks and solid oxide electrolytic cells (hereinafter referred to as SOFC and SOEC), bonding materials are required to electrically and physically connect the electrochemical elements (cells) and the inter-cell connecting members (see Patent Documents 1, 2, and 3). Common bonding materials include non-metallic oxide materials and precious metal materials such as Ag and Pt, which are used to connect the air electrode of the cell to the cell-to-cell connecting members (alloys or alloys with coatings), and are required to have low resistance and high adhesion. Precious metal materials such as Pt and Ag exhibit low resistance and high adhesion in the operating environment, but Pt is a very expensive material, and Ag poses risks of evaporation and short circuits due to deposition in the insulating part in the operating environment of SOFCs. Examples of bonding materials used in SOFC cell stacks include non-metallic oxide materials such as perovskite oxides and spinel oxides. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2016-195101 [Patent Document 2] Japanese Patent Publication No. 2015-088446 [Patent Document 3] Japanese Patent Publication No. 2015-201422 [Overview of the project] [Problems that the invention aims to solve]

[0004] Perovskite oxides are used with compositions similar to those used for air electrode materials, and examples of such compositions include oxides based on La-Sr-Co-Fe-O, La-Sr-Mn-O, and La-Sr-Ni-O systems. These materials have affinity with the air electrode, and also exhibit a matching coefficient of thermal expansion and high electronic conductivity. On the other hand, achieving high adhesion generally requires temperatures above 1000°C, and depending on the configuration of the SOFC / SOEC cell stack, such as a flat plate structure or a metal-supported structure, they may not be usable due to temperature constraints. For example, concerns include metal-supported SOFC / SOEC, parts that cannot withstand temperatures above 1000°C (such as glass seal sections), and sintering of electrode materials.

[0005] On the other hand, spinel oxides are composed of one or more transition metals such as Co-Mn, Cu-Mn, Co-Ni, Co-Ni-Mn, and Ni-Mn, and have high electronic conductivity, a matching coefficient of thermal expansion with the cell material, and can be baked at a lower temperature than perovskite oxides (800°C). However, due to constraints of metal-supported SOFC cell stacks and glass seal members, baking may not be possible even at 800°C, and a material that can bake the bonding material at an even lower temperature is desired. Furthermore, to further improve the performance of cell stacks, bonding materials that do not hinder the supply of oxygen to the air electrode or oxygen-generating electrode are required. To increase the oxygen supply to the air electrode (or oxygen-generating electrode), it is desirable for the bonding material to be porous, and further research was needed.

[0006] The present invention has been made in view of the above-mentioned problems, and its objective is to provide a bonding material, an electrochemical module, a solid oxide fuel cell, a solid oxide electrolytic cell, an electrochemical device, an energy system, and a method for manufacturing an electrochemical module, which can be fired at relatively low temperatures and can ensure a good supply of oxygen to the air electrode (or oxygen generating electrode) under operating conditions. [Means for solving the problem]

[0007] The joining material for achieving the above objective is: A bonding material for joining an electrochemical element and an inter-cell connecting member by firing, wherein the electrode layer, electrolyte layer, and counter electrode layer are stacked in the order described above, and its characteristic configuration is: The key feature is that it is made by mixing a porous resin that volatilizes at temperatures between 200°C and 300°C with a CoMn metal oxide, which is a metal oxide containing particulate Co and Mn.

[0008] To solve the aforementioned problems, the inventors have been developing technologies for bonding at temperatures below 800°C by developing diffusion bonding of Co and Mn-based materials, metal doping, and fine particle technology. According to the above characteristic configuration, by using a bonding material made by mixing a porous resin that volatilizes at 200°C to 300°C and a CoMn metal oxide, which is a metal oxide containing particulate Co and Mn, the porous resin volatilizes at a much lower temperature than the sintering temperature, 200°C to 300°C. Therefore, after sintering at the sintering temperature, the areas where the porous resin was present can be made porous. As a result, it is possible to create a bonding material that allows for baking at relatively low temperatures and enables a good supply of oxygen to the air electrode (or oxygen generating electrode) under operating conditions.

[0009] Further characteristic features of the bonding material are: The particulate porous resin before volatilization has a maximum length of 1.5 μm or more and 3.0 μm or less between the ends of the particles.

[0010] As described above, by using porous resin before volatilization in which the maximum length connecting one end of the particle to the other is between 1.5 μm and 3.0 μm, it is possible to allow good gas (oxygen) to flow through the interior, and tests described later have confirmed that it is possible to realize a bonding material that exhibits good low resistance (high conductivity) and adhesion.

[0011] Further characteristic features of the bonding material are: The key point is that the volume ratio of voids to the total volume is between 20% and 45%.

[0012] As described in the above characteristic configuration, by setting the volume ratio of pores to the total volume of the bonding material to be 20% by volume (vol%) or more and 45% by volume (vol%) or less, it is possible to appropriately make the bonding material porous while ensuring good adhesion. In addition, when the volume ratio of pores to the total volume is less than 20% by volume, there is a risk that sufficient air flow cannot occur inside the bonding material and sufficient oxygen supply to the air electrode (or oxygen generation electrode) cannot be achieved. When the volume ratio of pores to the total volume exceeds 45% by volume, there is a risk that the adhesion decreases and the contact resistance increases.

[0013] A further characteristic configuration of the bonding material is that the volume ratio of pores to the total volume is 32% by volume or more and 45% by volume or less.

[0014] The inventors have particularly set the volume ratio of pores to the total volume of the bonding material to be 32% by volume (vol%) or more and 45% by volume (vol%) or less. As shown in the test results described later, at a firing temperature of 800 °C, it is possible to improve the cell performance by improving gas diffusibility and to make the contact resistance low enough to withstand practical use.

[0015] A further characteristic configuration of the bonding material is that the pore-forming resin is methyl polymethacrylate.

[0016] As described above, in electrochemical elements, particularly in electrochemical modules joined with a bonding material, it is preferable to lower the baking temperature in order to improve durability. However, the high adhesion and low resistance of the bonding material are in a trade-off relationship with the baking temperature. More specifically, there has been a problem that as the baking temperature decreases, the adhesion decreases and the contact resistance increases. The inventors have confirmed by the tests described later that by using methyl polymethacrylate as the pore-forming resin as in the above characteristic configuration, sufficient adhesion and low resistance can be achieved even at a relatively low baking temperature (for example, a temperature of about 700 °C or more and 900 °C or less: preferably 800 °C).

[0017] A method for manufacturing an electrochemical module to achieve the above objective is: A method for manufacturing an electrochemical module in which an electrochemical element, in which an electrode layer, an electrolyte layer, and a counter electrode layer are stacked in the order described above, and an inter-cell connecting member are joined together with a bonding material, the characteristic configuration thereof is: The aforementioned bonding material includes a mixing step of mixing a porous resin that volatilizes at temperatures between 200°C and 300°C and a CoMn metal oxide which is a metal oxide containing particulate Co and Mn, The present invention includes a firing step in which the bonding material mixed in the mixing step is filled between the electrochemical element and the cell-to-cell connecting member and fired.

[0018] Furthermore, regarding the manufacturing method of the electrochemical module, by employing a manufacturing method that includes a mixing step of mixing a porous-forming resin that volatilizes at 200°C to 300°C and a CoMn metal oxide, which is a metal oxide containing particulate Co and Mn, as a bonding material, and a firing step of filling the bonding material mixed in the mixing step between the electrochemical element and the cell-to-cell connecting member and firing, the porous-forming resin volatilizes at a much lower temperature of 200°C to 300°C than the sintering temperature, so that the area where the porous-forming resin was present can be made porous after sintering at the sintering temperature. As a result, it is possible to manufacture an electrochemical module that can be fired at a relatively low temperature and that can achieve good oxygen supply to the air electrode (or oxygen generation electrode) under operating conditions.

[0019] Further manufacturing methods for electrochemical modules are: The key feature is that the volume percentage of the porous resin mixed as the bonding material in the mixing step is less than 24% by volume.

[0020] As described above, by setting the volume percentage of the porous-forming resin mixed as a bonding agent in the mixing process to less than 24 vol% (vol%), the aggregation of the porous-forming resin can be effectively prevented. It has been confirmed that this effectively prevents the separation of porous and non-porous parts from forming in the conforming material after baking.

[0021] Further manufacturing methods for electrochemical modules are: The key feature is that the volume percentage of the porous resin mixed as the bonding material in the mixing step is 12% by volume or less.

[0022] As a result of diligent research, the inventors have confirmed that, as shown in the test results described later, by setting the volume ratio of the porous-forming resin mixed as a bonding agent in the mixing process to 12 volume% (vol%) or less, the aggregation of the porous-forming resin can be effectively prevented, and the separation of porous and non-porous portions in the conforming material after baking can be effectively prevented.

[0023] Further manufacturing methods for electrochemical modules are: The key point is that the volume percentage of voids in the joining material after the firing process is performed is set to be between 20% and 45% by volume.

[0024] As described above, by setting the volume ratio of pores to the total volume of the bonding material to 20 vol% or more and 45 vol% or less, it is possible to ensure good adhesion while appropriately making the bonding material porous. Furthermore, if the volume ratio of voids to the total volume is less than 20% by volume, there is a risk that sufficient air flow will not be possible inside the bonding material, and sufficient oxygen supply to the air electrode (or oxygen generating electrode) may not be possible. If the volume ratio of voids to the total volume exceeds 45% by volume, there is a risk that the adhesion will decrease and the contact resistance will increase.

[0025] Further manufacturing methods for electrochemical modules are: The key point is that the volume percentage of voids in the joining material after the firing process is performed is set to be between 32% and 45% by volume.

[0026] The inventors have confirmed that, in particular, by setting the volume ratio of voids to the total volume of the bonding material to 32 vol% or more and 45 vol% or less, it is possible to improve cell performance by improving gas diffusion at a firing temperature of 800°C, as shown in the test results described later, and to reduce the contact resistance to a level that is acceptable for practical use.

[0027] Further manufacturing methods for electrochemical modules are: In the aforementioned mixing step, the porous resin mixed as the bonding material has a maximum length of 1.5 μm or more and 3.0 μm or less between the ends of the particles.

[0028] As described above, by using porous resin before volatilization in which the maximum length connecting one end of the particle to the other is between 1.5 μm and 3.0 μm, it is possible to allow good gas (oxygen) to flow through the interior, thereby realizing a bonding material that exhibits good low resistance (high conductivity) and adhesion.

[0029] The characteristic configuration of the electrochemical module using the aforementioned bonding material is: The key feature is that multiple electrochemical elements are connected using the aforementioned bonding material and arranged in a bundled state.

[0030] According to the above characteristic configuration, by arranging multiple electrochemical elements in a clustered manner, it is possible to realize an electrochemical module that can be fired at relatively low temperatures and exhibit high gas diffusion performance under operating conditions. Furthermore, for example, when the electrochemical module is operated as a fuel cell, it becomes possible to obtain a large power output.

[0031] The characteristic configuration of a solid oxide fuel cell using the aforementioned bonding material is: The key feature is that the electrochemical elements connected by the aforementioned bonding material generate an electric power reaction.

[0032] According to the above characteristic configuration, a solid oxide fuel cell equipped with the electrochemical elements described above can perform power generation reactions, enabling firing at relatively low temperatures and providing a solid oxide fuel cell that exhibits high gas diffusion performance under operating conditions.

[0033] The characteristic configuration of the solid oxide type electrolytic cell using the bonding material described above is: The key feature is that an electrolytic reaction occurs in the electrochemical elements connected by the aforementioned bonding material.

[0034] According to the above characteristic configuration, a solid oxide electrolytic cell equipped with the electrochemical elements described above can generate gas through an electrolytic reaction, enabling firing at relatively low temperatures and obtaining a solid oxide electrolytic cell that exhibits high gas diffusion performance under operating conditions.

[0035] The characteristic configuration of the electrochemical apparatus using the electrochemical module described above is: The present invention has an electrochemical module and a fuel converter, and a fuel supply unit that supplies reducing component gas from the fuel converter to the electrochemical element or the electrochemical module, or supplies reducing component gas from the electrochemical element or the electrochemical module to the fuel converter.

[0036] According to the above-described configuration, when an electrochemical element or electrochemical module is operated as a fuel cell, it can be configured to generate hydrogen using a fuel converter such as a reformer, based on natural gas supplied using existing raw material supply infrastructure such as city gas. This enables firing at relatively low temperatures and allows for the realization of an electrochemical device equipped with an electrochemical element or electrochemical module that exhibits high gas diffusion performance under operating conditions. Furthermore, it becomes easier to construct a system for recycling unused fuel gas distributed from the electrochemical module, thus enabling the realization of a highly efficient electrochemical device. On the other hand, when an electrochemical element or electrochemical module is operated as an electrolytic cell, a gas containing water vapor or carbon dioxide is passed through the electrode layer, and a voltage is applied between the electrode layer and the counter electrode layer. In this case, electrons e are generated in the electrode layer. - Water (H2O) and carbon dioxide molecules (CO2) react with hydrogen (H2), carbon monoxide (CO), and oxygen ions (O). 2- This results in the generation of oxygen ions O 2- It moves through the electrolyte layer to the counter electrode layer. Then, in the counter electrode layer, oxygen ions O 2- The gas releases electrons to become oxygen (O2). Through the above reaction, if a gas containing water vapor is in circulation, water (H2O) is decomposed into hydrogen (H2) and oxygen (O2), and if a gas containing carbon dioxide molecules (CO2) is in circulation, it is electrolyzed into carbon monoxide (CO) and oxygen (O2). Therefore, when a gas containing water vapor and carbon dioxide molecules (CO2) is circulated, a fuel converter can be provided that synthesizes various compounds such as hydrocarbons from hydrogen and carbon monoxide generated by the electrochemical element or electrochemical module through the electrolysis described above. This makes it possible to circulate the hydrocarbons generated by the fuel converter to the electrochemical element or electrochemical module, or to extract them outside the system / device and use them separately as fuel or chemical raw materials.

[0037] The characteristic configuration of the electrochemical apparatus using the electrochemical module described above is: The electrochemical module mentioned above, The key feature is that it includes at least 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.

[0038] According to the above characteristic configuration, the power converter can extract the electricity generated by the electrochemical element or electrochemical module, or supply electricity to the electrochemical element or electrochemical module. As a result, the electrochemical element or electrochemical module acts as a fuel cell or as an electrolytic cell, as described above. Therefore, according to the above characteristic configuration, an electrochemical device with improved efficiency in converting chemical energy such as fuel into electrical energy, or electrical energy into chemical energy such as fuel, can be realized while being able to be fired at relatively low temperatures and exhibiting high gas diffusion performance under operating conditions. Furthermore, for example, when an inverter is used as a power converter, it is preferable when operating as a fuel cell because the inverter can boost the voltage or convert DC to AC, making it easier to utilize the electrical output obtained from the electrochemical element or electrochemical module. Also, when operating as an electrolytic cell, it is preferable to construct an electrochemical device that can obtain DC from an AC power source and supply DC power to the electrochemical element or electrochemical module.

[0039] The characteristic configuration of the energy system using the electrochemical apparatus described above is: The electrochemical apparatus described above, The distinguishing feature is that it includes at least a waste heat utilization unit that reuses the heat discharged from the electrochemical apparatus.

[0040] According to the above-described configuration, it is possible to realize an energy system that is CO-free, economically superior, and highly energy-efficient. Furthermore, it is possible to realize an energy-efficient hybrid system by combining it with a power generation system that generates electricity using the combustion heat of unused fuel gas emitted from electrochemical equipment. [Brief explanation of the drawing]

[0041] [Figure 1] This is a schematic diagram of the electrochemical module. [Figure 2] This diagram shows the components that make up an electrochemical module. [Figure 3] This is a cross-sectional SEM image of the portion of the electrochemical module containing the bonding material, relating to the comparative example. [Figure 4] This is a cross-sectional SEM image of the portion of the electrochemical module according to Example 1 that includes the bonding material. [Figure 5]This is a cross-sectional SEM image of the portion of the electrochemical module according to Example 2 that includes the bonding material. [Figure 6] This is a cross-sectional SEM image of the portion of the electrochemical module according to Example 3 that includes the bonding material. [Figure 7] The following graphs illustrate the relationship between porosity and AR value at 800°C in the examples and comparative examples. [Figure 8] This graph shows the relationship between the amount of porous-forming resin (PMMA) added and the degree of porosity. [Figure 9] This diagram shows the configuration of an energy system and an electrochemical apparatus. [Figure 10] This diagram shows the configuration of an energy system and an electrochemical apparatus. [Modes for carrying out the invention]

[0042] The bonding material, electrochemical module, solid oxide fuel cell, solid oxide electrolytic cell, electrochemical device, energy system, and method for manufacturing the electrochemical module according to the embodiment relate to a material that can be baked at a relatively low temperature and can achieve low resistance and high adhesion under operating conditions. The following description, based on the drawings, will explain the bonding material, electrochemical module, solid oxide fuel cell, solid oxide electrolytic cell, electrochemical apparatus, and energy system according to the embodiment.

[0043] Figure 1 shows the configuration of an electrochemical module M. Figure 2 is a diagram illustrating the components that make up the electrochemical module M. As shown in the figures, the electrochemical module M comprises an alloy member 26, electrochemical elements E, and a joining material 10 that joins the alloy member 26 (an example of an inter-cell connecting member) and the electrochemical elements E. In particular, the electrochemical module M shown in Figure 1 comprises a plurality of electrochemical elements E, and the plurality of electrochemical elements E are electrically connected to each other by the alloy member 26. In this specification, the term "inter-cell connecting member" refers to interconnectors, separators, current collectors, etc.

[0044] The electrochemical element E has a single cell C in which an electrolyte layer 4 is sandwiched between an electrode layer 2 and a counter electrode layer 6. In this embodiment, the electrochemical element E has a single cell C on a metal support (metal substrate) 1 having through holes 1a. The single cell C in this embodiment comprises an electrode layer 2, an intermediate layer 3, an electrolyte layer 4, a reaction prevention layer (intermediate layer) 5, and a counter electrode layer 6.

[0045] The electrochemical element E is used, for example, as a component of a solid oxide fuel cell that generates electricity by receiving a hydrogen-containing fuel gas and air. When explaining the positional relationship of the layers, for example, the side of the counter electrode layer 6 viewed from the electrolyte layer 4 may be called "upper" or "upper side," and the side of the electrode layer 2 may be called "lower" or "lower side." Also, the side of the metal support 1 on which the electrode layer 2 is formed may be called the front side, and the opposite side may be called the back side.

[0046] The electrochemical element E comprises a metal support 1, an electrode layer 2 formed on the metal support 1, an intermediate layer 3 formed on the electrode layer 2, an electrolyte layer 4 formed on the intermediate layer 3, a reaction prevention layer 5 formed on the electrolyte layer 4, and a counter electrode layer 6 formed on the reaction prevention layer 5. In other words, the counter electrode layer 6 is formed on the electrolyte layer 4, and the reaction prevention layer 5 is formed between the electrolyte layer 4 and the counter electrode layer 6. For example, the electrode layer 2 is porous, and the electrolyte layer 4 is dense.

[0047] The metal support 1 supports the single cell C, which is composed of an electrolyte layer 4 sandwiched between an electrode layer 2 and a counter electrode layer 6, thereby maintaining the strength of the electrochemical element E. In other words, the metal support 1 plays the role of a support for the electrochemical element E.

[0048] The material used for the metal support 1 is one that exhibits excellent electronic conductivity, heat resistance, oxidation resistance, and corrosion resistance. For example, ferritic stainless steel, austenitic stainless steel, and nickel-based alloys are used, but are not limited to these. In particular, alloys containing Cr are preferably used. In this embodiment, the material for the metal support 1 is an Fe-Cr alloy containing 18% to 25% by mass of Cr, but it is preferable to contain 0.05% or more by mass of Mn, and it is preferable to contain 0.05% to 1.0% by mass of Ni. Furthermore, for Cu, the lower limit is preferably 0.01% or more by mass, more preferably 0.10% or more by mass, and even more preferably 0.20% or more by mass, and the upper limit is preferably 1.0% or less by mass, more preferably 0.9% or less by mass, and even more preferably 0.8% or less by mass. Furthermore, the lower limit of the Ti content is preferably 0.05% by mass or more, more preferably 0.10% by mass or more, and even more preferably 0.15% by mass or more. The upper limit is preferably 1.0% by mass or less, more preferably 0.9% by mass or less, and even more preferably 0.8% by mass or less. By using such an Fe-Cr alloy, it is possible to use an alloy member with excellent performance, durability, and corrosion resistance as the metal support 1 while suppressing costs.

[0049] The metal support 1 is plate-shaped overall. The metal support 1 has a front surface on which the electrode layer 2 is provided, and has multiple through holes 1a that penetrate between the front surface and the back surface. The through holes 1a have the function of allowing gas to pass through between the front and back surfaces of the metal support 1. This allows for the smooth supply of fuel gas and oxidizer gas from the back surface of the metal support 1 to the electrode layer 2, thereby realizing a high-performance electrochemical element E. It is also possible to bend the plate-shaped metal support 1 to deform it into shapes such as a box or cylinder for use.

[0050] The electrode layer 2 can be provided as a thin layer on the surface of the metal support 1 so as to cover the through-hole 1a of the metal support 1. When it is a thin layer, its thickness can be, for example, about 1 μm to 100 μm, preferably 5 μm to 50 μm. With such a thickness, it is possible to reduce the amount of expensive electrode layer 2 material used, thereby lowering costs, while ensuring sufficient electrode performance.

[0051] For the electrode layer 2, composite materials such as NiO-GDC, Ni-GDC, NiO-YSZ, Ni-YSZ, CuO-CeO2, and Cu-CeO2 can be used. In these examples, GDC, YSZ, and CeO2 can be called aggregates of the composite material. The electrode layer 2 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 higher than 1100°C), a spray coating method (such as thermal spraying, aerosol deposition, aerosol gas deposition, powder jet deposition, particle jet deposition, and cold spray), a PVD method (such as sputtering and pulsed laser deposition), or a CVD method.

[0052] Electrode layer 2 has multiple pores on its interior and surface to allow gas permeability. In other words, electrode layer 2 is formed as a porous layer. Electrode layer 2 is formed, for example, so that its density is between 30% and less than 80%. The size of the pores can be appropriately selected to ensure smooth reaction during electrochemical reactions. Density is the ratio of the material constituting the layer to the surrounding space, and can be expressed as (1 - porosity), and is equivalent to relative density.

[0053] The intermediate layer 3 can be formed as a thin layer on the electrode layer 2. When forming a thin layer, its thickness can be, for example, about 1 μm to 100 μm, preferably about 2 μm to 50 μm, and more preferably about 4 μm to 25 μm. Such a thickness makes it possible to reduce the amount of expensive intermediate layer material used, thereby lowering 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. Ceria-based ceramics are particularly preferred.

[0054] The intermediate layer 3 is preferably formed by low-temperature firing (for example, a wet method using firing in a low temperature range without firing in a high temperature range higher than 1100°C), spray coating (such as thermal spraying, aerosol deposition, aerosol gas deposition, powder jet deposition, particle jet deposition, and cold spray), PVD (such as sputtering and pulsed laser deposition), or CVD. These film formation processes, which can be used in low temperature ranges, allow for the acquisition of the intermediate layer 3 without using firing in a high temperature range higher than 1100°C.

[0055] The intermediate layer 3 preferably has oxygen ion (oxide ion) conductivity. It is even more preferable if it has mixed conductivity between oxygen ions (oxide ions) and electrons. An intermediate layer 3 having these properties is suitable for application to an electrochemical element E.

[0056] The electrolyte layer 4 is formed as a thin layer on top of the intermediate layer 3. It can also be formed as a thin film with a thickness of 10 μm or less.

[0057] The materials for the electrolyte layer 4 include YSZ (yttria-stabilized zirconia), SSZ (scandium-stabilized zirconia), GDC (gadolinium-doped ceria), YDC (yttrium-doped ceria), SDC (samarium-doped ceria), LSGM (strontium-magnesium-doped lanthanum gallate), and LSO (lanthanum silicate, La 9.33+x Si6O 26+2x / 3 Electrolyte materials that conduct oxygen ions, such as ) and electrolyte materials that conduct hydrogen ions, such as perovskite-type oxides, can be used. Zirconia-based ceramics are particularly preferred. If 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 compared to ceria-based ceramics and various hydrogen ion conductive materials. For example, when using the electrochemical element E in an SOFC, if the electrolyte layer 4 is made of a material such as YSZ that can exhibit high electrolyte performance even in high temperature ranges of around 650°C or higher, and the system uses hydrocarbon-based raw fuels such as city gas or LPG as the raw fuel, and the raw fuel is converted into the anode gas of the SOFC by steam reforming, a highly efficient SOFC system can be constructed that uses the heat generated in the SOFC cell stack to reform the raw fuel gas.

[0058] The electrolyte layer 4 is preferably formed by low-temperature firing (for example, a wet method using firing in a low temperature range without firing in a high temperature range exceeding 1100°C), spray coating (such as thermal spraying, aerosol deposition, aerosol gas deposition, powder jet deposition, particle jet deposition, and cold spray), PVD (such as sputtering and pulsed laser deposition), or CVD. These film formation processes, usable in low temperature ranges, allow for the creation of a dense, airtight, and highly gas-barrier electrolyte layer 4 without using firing in a high temperature range exceeding 1100°C. In particular, using low-temperature firing or spray coating is preferable because it enables the realization of low-cost devices. Furthermore, using spray coating is even preferable because a dense, airtight, and highly gas-barrier electrolyte layer 4 can be easily obtained in a low temperature range.

[0059] The electrolyte layer 4 is densely constructed to shield against gas leaks of anode and cathode gases and to exhibit high ionic conductivity. The density of the electrolyte layer 4 is preferably 90% or higher, more preferably 95% or higher, and even more preferably 98% or higher. If the electrolyte layer 4 is a uniform layer, its density is preferably 95% or higher, and more preferably 98% or higher. Furthermore, if the electrolyte layer 4 is composed of multiple layers, it is preferable that at least a portion of it includes a layer with a density of 98% or higher (a dense electrolyte layer), and more preferably a layer with a density of 99% or higher (a dense electrolyte layer). This is because including such a dense electrolyte layer as part of the electrolyte layer 4 makes it easier to form a dense electrolyte layer 4 with high airtightness and gas barrier properties, even when the electrolyte layer 4 is composed of multiple layers.

[0060] The reaction prevention layer 5 can be formed as a thin layer on the electrolyte layer 4. When forming a thin layer, its thickness can be, for example, about 1 μm to 100 μm, preferably about 2 μm to 50 μm, and more preferably about 3 μm to 15 μm. By using such a thickness, it is possible to reduce the amount of expensive reaction prevention layer material used, thereby lowering costs while ensuring sufficient performance.

[0061] The reaction prevention layer 5 can be made of any material capable of preventing the reaction between the components of the electrolyte layer 4 and the components of the counter electrode layer 6, such as ceria-based materials. Preferably, the reaction prevention layer 5 is made of a material containing at least one element selected from the group consisting of Sm, Gd, and Y. It is preferable that the material contains at least one element selected from the group consisting of Sm, Gd, and Y, and that the total content of these elements is between 1.0% by mass and 10% by mass. By introducing the reaction prevention layer 5 between the electrolyte layer 4 and the counter electrode layer 6, the reaction between the constituent materials of the counter electrode layer 6 and the constituent materials of the electrolyte layer 4 is effectively suppressed, improving the long-term stability of the performance of the electrochemical element E. It is preferable to form the reaction prevention layer 5 using a method that can be performed at a processing temperature of 1100°C or lower, as this suppresses damage to the metal support 1 and also suppresses elemental diffusion between the metal support 1 and the electrode layer 2, thereby realizing an electrochemical element E with excellent performance and durability. For example, the process can be carried out using appropriate methods such as low-temperature firing (e.g., a wet method using firing in a low temperature range without firing in a high temperature range exceeding 1100°C), spray coating (such as thermal spraying, aerosol deposition, aerosol gas deposition, powder jet deposition, particle jet deposition, and cold spray), PVD (such as sputtering and pulsed laser deposition), and CVD. In particular, low-temperature firing and spray coating methods are preferable because they enable the realization of low-cost devices. Furthermore, using low-temperature firing is even preferable because it simplifies the handling of raw materials.

[0062] The counter electrode layer 6 can be formed as a thin layer on top of the reaction prevention layer 5. If the reaction prevention layer 5 is not provided, the counter electrode layer 6 is formed on top of the electrolyte layer 4. When it is a thin layer, its thickness can be, for example, about 1 μm to 100 μm, preferably 5 μm to 50 μm. Such a thickness makes it possible to reduce the amount of expensive counter electrode layer material used, thereby lowering costs while ensuring sufficient electrode performance. As the material for the counter electrode layer 6, for example, composite oxides such as LSCF and LSM, ceria oxides, and mixtures thereof can be used. In particular, it is preferable that the counter electrode layer 6 contains a perovskite-type oxide containing two or more elements selected from the group consisting of La, Sr, Sm, Mn, Co, and Fe. The counter electrode layer 6 constructed using the above materials functions as a cathode.

[0063] Furthermore, it is preferable to form the counter electrode layer 6 using a method that can be performed at a processing temperature of 1100°C or lower, as this suppresses damage to the metal support 1 and inhibits elemental diffusion between the metal support 1 and the electrode layer 2, thereby realizing an electrochemical element E with excellent performance and durability. For example, this can be done using a low-temperature firing method (e.g., a wet method using firing in a low temperature range without firing in a high temperature range exceeding 1100°C), a spray coating method (such as thermal spraying, aerosol deposition, aerosol gas deposition, powder jet deposition, particle jet deposition, or cold spray), a PDV method (such as sputtering or pulsed laser deposition), or a CVD method as appropriate. In particular, using a low-temperature firing method or a spray coating method is preferable because it enables the realization of a low-cost element. Moreover, using a low-temperature firing method is even preferable because it simplifies the handling of raw materials.

[0064] By constructing the electrochemical element E as described above, the electrochemical element E can be used as a power generation cell of a solid oxide fuel cell. For example, a fuel gas containing hydrogen is passed through the through-hole 1a from the back surface of the metal support 1 to the electrode layer 2, and air is passed through to the counter electrode layer 6 that serves as the counter electrode of the electrode layer 2, and it is operated, for example, at a temperature of 500 °C or higher and 900 °C or lower. Then, oxygen O2 contained in the air reacts with electrons e - to produce oxygen ions O 2- . The oxygen ions O 2- move through the electrolyte layer 4 to the electrode layer 2. In the electrode layer 2, hydrogen H2 contained in the supplied fuel gas reacts with oxygen ions O 2- to produce 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 releases electrons e- to produce hydrogen ions H + . The hydrogen ions H + move through the electrolyte layer 4 to the counter electrode layer 6. In the counter electrode layer 6, oxygen O2 contained in the air reacts with hydrogen ions H + and electrons e - to produce water H2O. Due to the above reactions, an electromotive force is generated between the electrode layer 2 and the counter electrode layer 6. In this case, the electrode layer 2 functions as the fuel electrode (anode) of the SOFC, and the counter electrode layer 6 functions as the air electrode (cathode). Thus, a solid oxide fuel cell including the electrochemical module M and causing a power generation reaction in the single cell C is realized.

[0065] Next, a method for manufacturing the electrochemical module M will be described.

[0066] In the electrode layer formation step, the electrode layer 2 is formed as a thin film on the metal support 1. As described above, the electrode layer 2 can be formed using methods such as low-temperature firing (wet firing method at a low temperature of 1100°C or below), spray coating (thermal spraying, aerosol deposition, aerosol gas deposition, powder jet deposition, particle jet deposition, cold spray, etc.), PVD (sputtering, pulsed laser deposition, etc.), and CVD. In any case, it is desirable to perform the process at a temperature of 1100°C or below to suppress deterioration of the metal support 1.

[0067] When the electrode layer formation step is performed by a low-temperature firing method, the process is carried out as follows: First, the material powder for electrode layer 2 and the solvent (dispersion medium) are mixed to create a material paste, which is then applied to the front surface of the metal support 1. Then, electrode layer 2 is compression molded (electrode layer smoothing step) and fired at 1100°C or below (electrode layer firing step). Compression molding of electrode layer 2 can be performed by methods such as CIP (Cold Isostatic Pressing), roll press molding, or RIP (Rubber Isostatic Pressing). Furthermore, firing of electrode layer 2 is preferably performed at a temperature between 800°C and 1100°C. The order of the electrode layer smoothing step and the electrode layer firing step can also be reversed. Furthermore, when forming an electrochemical element E having an intermediate layer 3, the electrode layer smoothing step and the electrode layer firing step can be omitted, or the electrode layer smoothing step and the electrode layer firing step can be included in the intermediate layer smoothing step and the intermediate layer firing step described later. The electrode layer smoothing step can also be performed by lapping, leveling, surface cutting, polishing, etc.

[0068] In the intermediate layer formation step, an intermediate layer 3 is formed on top of the electrode layer 2 in a thin layer, covering the electrode layer 2. As described above, the intermediate layer 3 can be formed using methods such as low-temperature firing (wet firing method at low temperatures of 1100°C or below), spray coating (thermal spraying, aerosol deposition, aerosol gas deposition, powder jet deposition, particle jet deposition, cold spray, etc.), PVD (sputtering, pulsed laser deposition, etc.), and CVD. In any case, it is desirable to perform the process at a temperature of 1100°C or below in order to suppress the deterioration of the metal support 1.

[0069] When the intermediate layer formation step is performed by a low-temperature firing method, it is specifically carried out as follows: First, the material powder of the intermediate layer 3 and a solvent (dispersion medium) are mixed to create a material paste, which is then applied to the front surface of the metal support 1. Then, the intermediate layer 3 is compressed and molded (intermediate layer smoothing step), and fired at 1100°C or below (intermediate layer firing step). The rolling of the intermediate layer 3 can be carried out by, for example, CIP (Cold Isostatic Pressing), roll pressing, or RIP (Rubber Isostatic Pressing). Furthermore, it is preferable to fire the intermediate layer 3 at a temperature between 800°C and 1100°C. This is because at such a temperature, a high-strength intermediate layer 3 can be formed while suppressing damage and deterioration of the metal support 1. It is even more preferable to fire the intermediate layer 3 at 1050°C or below, and even more preferable to fire it at 1000°C or below. This is because lowering the firing temperature of the intermediate layer 3 allows for the formation of the electrochemical element E while further suppressing damage and deterioration of the metal support 1. Furthermore, the order of the intermediate layer smoothing process and the intermediate layer firing process can be reversed. The intermediate layer smoothing process can also be performed by methods such as lapping, leveling, or surface cutting and polishing.

[0070] In the electrolyte layer formation step, the electrolyte layer 4 is formed as a thin layer on the intermediate layer 3, covering the electrode layer 2 and the intermediate layer 3. Alternatively, it may be formed as a thin film with a thickness of 10 μm or less. As described above, the electrolyte layer 4 can be formed using methods such as low-temperature firing (wet firing method at a low temperature of 1100°C or less), spray coating (thermal spraying, aerosol deposition, aerosol gas deposition, powder jet deposition, particle jet deposition, cold spray, etc.), PVD (sputtering, pulsed laser deposition, etc.), and CVD. In any case, it is desirable to perform the process at a temperature of 1100°C or less to suppress deterioration of the metal support 1.

[0071] In order to form a high-quality electrolyte layer 4 that is dense, airtight, and has excellent gas barrier properties at a temperature of 1100°C or lower, it is desirable to perform the electrolyte layer formation step by spray coating. In this case, the material for the electrolyte layer 4 is sprayed toward the intermediate layer 3 on the metal support 1 to form the electrolyte layer 4.

[0072] In the reaction prevention layer formation step, the reaction prevention layer 5 is formed as a thin layer on the electrolyte layer 4. As described above, the reaction prevention layer 5 can be formed using methods such as low-temperature firing (wet firing process at a low temperature of 1100°C or below), spray coating (thermal spraying, aerosol deposition, aerosol gas deposition, powder jet deposition, particle jet deposition, cold spray, etc.), PVD (sputtering, pulsed laser deposition, etc.), and CVD. In any case, it is desirable to perform the process at a temperature of 1100°C or below to suppress deterioration of the metal support 1. In addition, in order to make the upper surface of the reaction prevention layer 5 flat, for example, leveling treatment or surface cutting and polishing treatment may be performed after the formation of the reaction prevention layer 5, or press processing may be performed after wet formation and before firing.

[0073] In the counter electrode layer formation step, the counter electrode layer 6 is formed as a thin layer on the reaction prevention layer 5. As described above, the counter electrode layer 6 can be formed using methods such as low-temperature firing (wet firing method at a low temperature of 1100°C or lower), spray coating (thermal spraying, aerosol deposition, aerosol gas deposition, powder jet deposition, particle jet deposition, cold spray, etc.), PVD (sputtering, pulsed laser deposition, etc.), and CVD. In any case, it is desirable to perform the process at a temperature of 1100°C or lower to suppress deterioration of the metal support 1.

[0074] As described above, an electrochemical module M can be fabricated as shown in Figures 1 and 2 by sequentially joining the electrochemical element E and the alloy member 26 in series using the bonding material 10. Specifically, the counter electrode layer 6 of the electrochemical element E and the alloy member 26 are joined using the bonding material 10. In addition, a U-shaped member 9 is joined to the back side of the metal support 1 of the electrochemical element E, and the alloy member 26 is joined to the U-shaped member 9. In other words, the alloy member 26 is joined to the counter electrode layer 6 of the electrochemical element E and the U-shaped member 9, electrically connecting the two. A cylindrical support is formed by the metal support 1 and the U-shaped member 9. Gas flowing through the internal space of the cylindrical support is supplied to the electrode layer 2 through the through hole 1a of the metal support 1. It is preferable that the material of the U-shaped member 9 is the same metallic material as the metal support 1, from the viewpoint of reducing the difference in thermal expansion with the metal support 1 and ensuring the reliability of the joint, such as welding.

[0075] The alloy member 26 is made of a material containing Fe and Cr. For example, the alloy member 26 can be made of ferritic stainless steel, Fe-Cr-Ni alloy which is an austenitic stainless steel with superior heat resistance, or a nickel-based alloy. It is preferable that the material of the alloy member 26 is the same as that of the metal support 1, from the viewpoint of reducing the difference in thermal expansion with the metal support 1.

[0076] The manufacturing method of the electrochemical module M of this embodiment will now be described. As shown in Figure 1, each of the multiple electrochemical elements E is stacked and arranged such that it faces an alloy member 26 on the counter electrode layer 6 side via a bonding material 10, and faces another alloy member 26 on the metal support 1 side via a U-shaped member 9. As part of the manufacturing method of the electrochemical module M, a bonding process is performed in which the bonding material 10 is placed between the alloy member 26 and the electrochemical element E and fired at a temperature of less than 1000°C. For example, a joining process is performed in which a paste containing material fine particles of the joining material 10 is placed between the alloy member 26 and the electrochemical element E and fired. As a result, the alloy member 26 and the electrochemical element E can be joined using the joining material 10 to join the two. In addition, the firing temperature in the joining process is more preferably 900°C or lower, and even more preferably 800°C or lower, as a lower firing temperature reduces the damage to the electrochemical module M. Furthermore, in order to ensure good bonding performance, the firing temperature is preferably 600°C or higher, more preferably 650°C or higher, and even more preferably 700°C or higher.

[0077] In particular, the method for manufacturing an electrochemical module M in which an electrochemical element E and an alloy member 26 (an example of an inter-cell connecting member) are joined by the joining material 10 according to the present embodiment includes a mixing step of mixing a porous-forming resin that volatilizes at 200°C to 300°C and a CoMn metal oxide which is a metal oxide containing particulate Co-Mn, and a firing step of firing the joining material 10 mixed in the mixing step by filling it between the electrochemical element E and the alloy member 26.

[0078] To elaborate, when stacking SOFC / SOEC cells, which use metal or ceramics as a support, the cells are connected to each other using a bonding paste. The bonding paste is prepared by mixing bonding powder particles (which in this case contain at least a porous resin that volatilizes between 200°C and 300°C, and particulate CoMn metal oxide) with an organic solvent (solvent and binder). The mixing method involves, for example, using a rotating mill to form a paste. Afterward, the paste is applied (filled) between the air electrode of the cell (oxygen generation electrode in SOEC) and the interconnector, connected, and baked at approximately 700-850°C to form a stack. A drying process at approximately 100-350°C may be performed after applying the paste, but this drying process is not required. The drying process is performed to evaporate the organic solvents contained in the paste. The paste can be applied to the entire surface of the air electrode, or only to the rib portion of the interconnector.

[0079] Furthermore, while polymethyl methacrylate (hereinafter sometimes abbreviated as PMMA) can be suitably used as the porous-forming resin, other materials such as resins that do not contain impurities that adversely affect cells, such as Si and S, can also be used.

[0080] Furthermore, in this manufacturing method, the volume percentage of the porous resin mixed as the bonding agent 10 in the above mixing step is preferably less than 24 volume% (vol%), and more preferably 12 volume% or less, in order to prevent condensation of the porous resin. Incidentally, it is preferable that the porous resin contains at least 5 volume% or more.

[0081] Incidentally, it is preferable that the porous resin mixed as the bonding material 10 in the mixing process has a maximum length of 1.5 μm or more and 3.0 μm or less between the ends of the particles. This allows the porous resin to form a large number of pores inside the bonding material 10 after it has evaporated due to heating, creating a state in which gas (oxygen) can easily pass through. The porous resin may include not only spherical particles but also ellipsoidal particles, fibrous materials, and other materials of various shapes.

[0082] Furthermore, from the viewpoint of maintaining a certain level of gas (oxygen) flowability, adhesion, and electrical conductivity in the bonding material 10 after the firing process, it is preferable that the volume percentage of voids in the bonding material 10 after the firing process is 20% by volume or more and 45% by volume or less, and more preferably 32% by volume or more and 45% by volume or less.

[0083] Furthermore, the maximum length connecting one end and the other end of the inner diameter of the void after baking is between 1.5 μm and 3.0 μm.

[0084] Next, we will explain the test results related to the bonding material 10. The bonding material 10 in Example 1 was prepared by adding 6% by volume of polymethyl methacrylate to CoMn metal oxide before the firing process; in Example 2, it was prepared by adding 12% by volume of polymethyl methacrylate to CoMn metal oxide before the firing process; in Example 3, it was prepared by adding 24% by volume of polymethyl methacrylate to CoMn metal oxide before the firing process; and the comparative example was pure Co-Mn metal oxide.

[0085] Comparative examples and cross-sectional SEM images of Examples 1-3 are shown in Figures 3-6. In Figures 3-6, the white to gray areas represent the Co-Mn skeleton, and the black areas represent the voids after the porous resin has evaporated. As shown in the cross-sectional SEM images of Figures 3-6, it can be seen that the number of voids increases as the amount (volume %) of the porous resin (polymethyl methacrylate: hereinafter sometimes abbreviated as PMMA) increases. However, as shown in Example 3 (see Figure 6), when the amount of porous resin added reached 24 volume%, the porous resin tended to aggregate and separate into porous and non-porous parts. From this, it is presumed that increasing the amount of porous resin added to the bonding material 10 to 24 volume% makes uniform bonding difficult, and it is preferable to keep it below 24 volume%.

[0086] Furthermore, Figure 7 shows the relationship between the porosity of the bonding material 10 and ASR (Area Specific Resistance). It was expected that increasing the porosity of the bonding material 10 would improve cell performance by improving gas diffusion (permeability of gases (oxygen)), but on the other hand, it was also expected that increasing the porosity would reduce the contact area between the Co-Mn skeletons, leading to a decrease in cell performance due to an increase in ASR. However, as shown in the results in Figure 7, we confirmed that increasing the porosity of the bonding material 10 described above has almost no effect on ASR.

[0087] ASR was measured by applying bonding material 10 uniformly to both sides of the SUS plate to a constant film thickness and measuring the voltage drop using the four-terminal method. The SUS plate was coated to prevent the diffusion of elements such as Cr (Co2MnO4 coating). Porosity was calculated by extracting a 30 μm rectangular area from a cross-sectional SEM image at a magnification of 2000x and performing binarization.

[0088] Next, adhesion tests were conducted on the comparative example and Examples 1-3. Samples were prepared by laminating the interconnector (Co2MnO4 coating), bonding material, and air electrode in that order, and then firing them at 850°C while applying a load. The prepared samples were then pulled with a constant force to qualitatively confirm their adhesion. As a result, it was confirmed that all of Examples 1-3, which were porousd using porous-forming resin, had adhesion comparable to that of the comparative example, which was not porousd. In other words, although there were concerns that the porous structure would reduce adhesion, it was confirmed that there were no problems with adhesion. Furthermore, the relationship between the amount of PMMA added (volume %) in the bonding material 10 and the porosity is shown in Figure 8.

[0089] Figure 9 shows the configuration of energy system Z and electrochemical apparatus Y. The energy system Z includes an electrochemical device Y and a heat exchanger 53 which serves as a waste heat utilization unit for reusing the heat discharged from the electrochemical device Y. The electrochemical apparatus Y comprises at least an electrochemical module M and a reformer 34, which acts as a fuel converter through which a gas containing reducing components flows to the electrochemical module M. In addition, the electrochemical apparatus Y comprises the electrochemical module M and an inverter 38, which acts as a power converter for extracting power from the electrochemical module M. Furthermore, the fuel supply module of the electrochemical apparatus Y consists of a desulfurizer 20, a vaporizer 33, and a reformer 34, etc., and supplies fuel gas containing reducing components to the electrochemical module M.

[0090] In addition, the electrochemical apparatus Y includes a reformed water tank 21, a blower 35, a combustion unit 36, a control unit 39, a storage container 40, a booster pump 41, a reformed water pump 43, and the like.

[0091] The vaporizer 33, reformer 34, electrochemical module M, and combustion section 36 are housed in a storage container 40. The reformer 34 uses the heat of combustion generated by the combustion of the reaction exhaust gas in the combustion section 36 to reform the raw fuel.

[0092] The raw fuel is supplied to the desulfurizer 20 through the raw fuel supply line 42 by the operation of the booster pump 41. The reformed water from the reformed water tank 21 is supplied to the vaporizer 33 through the reformed water supply line 44 by the operation of the reformed water pump 43. The raw fuel supply line 42 then merges with the reformed water supply line 44 downstream of the desulfurizer 20, and the reformed water and raw fuel, which have merged outside the storage container 40, are supplied to the vaporizer 33 located inside the storage container 40.

[0093] The desulfurizer 20 removes (desulfurizes) sulfur compounds contained in hydrocarbon raw fuels such as city gas. When sulfur compounds are present in the raw fuel, the desulfurizer 20 can suppress the influence of sulfur compounds on the reformer 34 or on the single cell C of the electrochemical element E that constitutes the electrochemical module M. The vaporizer 33 generates steam from the reformed water supplied from the reformed water tank 21. The raw fuel containing the steam generated in the vaporizer 33 is supplied to the reformer 34 through the steam-containing raw fuel supply passage 45.

[0094] The reformer 34 uses the steam generated in the vaporizer 33 to steam reform the raw fuel that has been desulfurized in the desulfurizer 20, thereby producing a reformed gas containing hydrogen. The reformed gas produced in the reformer 34 is supplied to the gas manifold 17 of the electrochemical module M through the reformed gas supply line 46.

[0095] The electrochemical elements E constituting the electrochemical module M are arranged in parallel, electrically connected to each other, and one end (lower end) of each electrochemical element E is fixed to the gas manifold 17. The reformed gas supplied to the gas manifold 17 is distributed to the multiple electrochemical elements E. The electrochemical elements E constituting the electrochemical module M generate electricity by performing an electrochemical reaction using the reformed gas supplied from the reformer 34 and the air supplied from the blower 35. The reaction exhaust gas, which includes residual hydrogen gas not used in the reaction, is discharged from the upper end of the electrochemical module M to the combustion section 36. The combustion section 36 mixes the reaction exhaust gas discharged from the electrochemical module M with air to burn the combustible components in the reaction exhaust gas.

[0096] The reaction exhaust gas burned in the combustion section 36 becomes combustion exhaust gas and is discharged to the outside of the storage container 40 from the combustion exhaust gas outlet 50. A combustion catalyst section 51 (for example, a platinum-based catalyst) is placed at the combustion exhaust gas outlet 50 to burn and remove reducing components such as carbon monoxide and hydrogen contained in the combustion exhaust gas. The combustion exhaust gas discharged from the combustion exhaust gas outlet 50 is sent to the heat exchanger 53 via the combustion exhaust gas discharge passage 52.

[0097] The heat exchanger 53 exchanges heat between the combustion exhaust gas generated by combustion in the combustion section 36 and the supplied chilled water to produce hot water. In other words, the heat exchanger 53 operates as a waste heat utilization unit that reuses the heat discharged from the electrochemical apparatus Y.

[0098] Alternatively, instead of a waste heat utilization unit, a reaction exhaust gas utilization unit may be provided that utilizes the reaction exhaust gas discharged (without combustion) from the electrochemical module M. The reaction exhaust gas contains residual hydrogen gas that was not used in the reaction by the electrochemical elements E that make up the electrochemical module M. In the reaction exhaust gas utilization unit, the residual hydrogen gas is used for heat utilization by combustion or power generation by fuel cells, etc., thereby enabling the efficient use of energy.

[0099] The inverter 38 adjusts the output power of the electrochemical module M to the same voltage and frequency as the power received from the commercial grid (not shown). The control unit 39 controls the operation of the electrochemical apparatus Y and the energy system Z.

[0100] <Another Embodiment> <1> In the above embodiment, an example of the structure of the electrochemical element E has been described, but the structure of the electrochemical element E can be changed as appropriate. For example, a configuration in which the electrochemical element E does not have a metal support 1 may be adopted, that is, a configuration in which the single cell C is not supported by the metal support 1.

[0101] <2> In the above embodiment, an example of using the electrochemical module M in a solid oxide fuel cell was described, but the electrochemical module M can also be used in solid oxide electrolytic cells, oxygen sensors using solid oxides, and the like.

[0102] In the above embodiment, a configuration that can improve the efficiency of converting chemical energy such as fuel into electrical energy was described. In other words, in the above embodiment, a single cell C as an electrochemical element E constituting the electrochemical module M is 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. As a result, oxygen molecules O2 in the counter electrode layer 6 have electrons e - It reacts with oxygen ions O 2- This is produced. The oxygen ion O 2- The hydrogen molecules H2 move through the electrolyte layer 4 to the electrode layer 2. In the electrode layer 2, the hydrogen molecules H2 move into oxygen ions O 2- It reacts with water (H2O) and electrons (e). - This is generated. Through the above reaction, an electromotive force is generated between electrode layer 2 and counter electrode layer 6, and electricity is generated.

[0103] This section describes a case where an electrolytic cell of the solid oxide type is realized, equipped with an electrochemical module M, and in which an electrolytic reaction occurs in a single cell C of the electrochemical element E. In the energy system Z shown in Figure 10, when the electrochemical element E constituting the electrochemical module M is operated as an electrolytic cell, a gas containing water vapor or carbon dioxide is passed through the electrode layer 2, which acts as the cathode (hydrogen generation electrode), and a voltage is applied between the electrode layer 2 and the counter electrode layer 6, which acts as the anode (oxygen generation electrode). Then, electrons e - Water molecules (H2O) and carbon dioxide molecules (CO2) react with hydrogen molecules (H2), carbon monoxide (CO), and oxygen ions (O). 2- This is the result. Oxygen ion O 2- The oxygen ions O move through the electrolyte layer 4 to the counter electrode layer 6. 2- The electrons are released to form oxygen molecules (O2). Through the above reaction, water molecules (H2O) are electrolyzed into hydrogen (H2) and oxygen (O2), and if a gas containing carbon dioxide molecules (CO2) is passed through, it is electrolyzed into carbon monoxide (CO) and oxygen (O2).

[0104] When a gas containing water vapor and carbon dioxide molecules (CO2) is being circulated, a fuel converter 91 can be provided to synthesize various compounds such as hydrocarbons from hydrogen and carbon monoxide produced by the electrochemical module M through electrolysis. A fuel supply unit (not shown) can circulate the hydrocarbons produced by this fuel converter 91 to the electrochemical module M, or it can be taken out of this system / device and used separately as fuel or chemical raw material. In other words, the fuel supply unit supplies reducing component gas from the fuel converter 91 to the electrochemical element E or the electrochemical module M, or supplies reducing component gas from the electrochemical element E or the electrochemical module M to the fuel converter 91.

[0105] Thus, in the energy system Z shown in Figure 10, the electrochemical device Y comprises at least an electrochemical module M and a fuel converter 91 that converts the gas containing reducing components generated by the electrochemical module M. The electrochemical device Y also comprises at least an electrochemical module M and a power converter 93 that supplies electricity to the electrochemical module M.

[0106] The electrochemical module M comprises multiple electrochemical elements E, a gas manifold 17, and a gas manifold 171. The multiple electrochemical elements E are arranged in parallel and electrically connected to each other. One end (lower end) of each electrochemical element E is fixed to the gas manifold 17, and the other end (upper end) is fixed to the gas manifold 171. The gas manifold 17 at one end (lower end) of the electrochemical element E receives a supply of water vapor and carbon dioxide. The hydrogen and carbon monoxide produced by the above-mentioned reaction in the electrochemical element E are collected by the gas manifold 171, which is in communication with the other end (upper end) of the electrochemical element E.

[0107] By configuring the heat exchanger 90 in Figure 10 to operate as a waste heat utilization unit that exchanges heat between the reaction heat generated by the reaction occurring in the fuel converter 91 and water to vaporize it, and by configuring the heat exchanger 92 in Figure 10 to operate as a waste heat utilization unit that exchanges heat between the waste heat generated by the electrochemical element E and water vapor and carbon dioxide to preheat it, energy efficiency can be increased. Furthermore, the power converter 93 supplies power to the single cell C that constitutes the electrochemical element E. As a result, the electrochemical element E acts as an electrolytic cell, as described above.

[0108] <3> In the above embodiment, composite materials such as NiO-GDC, Ni-GDC, NiO-YSZ, Ni-YSZ, CuO-CeO2, and Cu-CeO2 were used as the material for the electrode layer 2, and composite oxides such as LSCF and LSM were used as the material for the counter electrode layer 6. The electrochemical element E configured in this way can be used as a solid oxide fuel cell by supplying hydrogen gas to the electrode layer 2 to serve as the fuel electrode (anode) and supplying air to the counter electrode layer 6 to serve as the air electrode (cathode). It is also possible to modify this configuration so that the electrochemical element E can be configured so that the electrode layer 2 serves as the air electrode and the counter electrode layer 6 serves as the fuel electrode. Specifically, composite oxides such as LSCF and LSM can be used as the material for the electrode layer 2, and composite materials such as NiO-GDC, Ni-GDC, NiO-YSZ, Ni-YSZ, CuO-CeO2, and Cu-CeO2 can be used as the material for the counter electrode layer 6. With the electrochemical element E configured in this way, the electrode layer 2 can be supplied with air to serve as the air electrode and the counter electrode layer 6 can be supplied with hydrogen gas to serve as the fuel electrode, and the electrochemical element E can be used as a solid oxide fuel cell.

[0109] <4> In the above embodiment, the electrochemical element E may be configured without either the intermediate layer 3 (insertion layer) or the reaction prevention layer 5, or without both. That is, it is also possible to have a configuration in which the electrode layer 2 and the electrolyte layer 4 are in contact, or a configuration in which the electrolyte layer 4 and the counter electrode layer 6 are in contact. In this case, the intermediate layer formation step and the reaction prevention layer formation step are omitted in the above manufacturing method. It is also possible to add steps for forming other layers or to stack multiple layers of the same type.

[0110] <5> In the above embodiment, mainly planar or cylindrical planar solid oxide fuel cells were used as the electrochemical element E, but other electrochemical elements such as cylindrical solid oxide fuel cells can also be used.

[0111] <6> In the above embodiment, the electrochemical apparatus Y includes an electrochemical module M comprising a plurality of electrochemical elements E. However, the electrochemical apparatus Y of the above embodiment can also be applied to a configuration comprising a single electrochemical element E.

[0112] <7> 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 cylindrical support is formed by the two members, the metal support 1 and the U-shaped member 9. However, the cylindrical support may be formed by integrally forming the metal support 1 and the U-shaped member 9 using a single member, or by forming the cylindrical support using three or more members. Furthermore, the U-shaped member 9 may be omitted, and the electrode layer 2, etc., may be supported by the metal support 1.

[0113] <8> In the manufacturing method according to the above embodiment, the volume percentage of the porous resin mixed as the bonding material 10 in the mixing step is preferably less than 24 volume%, and more preferably 12 volume% or less, in order to prevent condensation of the porous resin. However, the volume ratio of the porous resin mixed as the bonding agent 10 in the mixing process is not limited to the above range.

[0114] <9> In the above embodiment, it was illustrated that it is preferable for the porous resin mixed as the bonding material 10 in the mixing step to have a maximum length of 1.5 μm or more and 3.0 μm or less connecting one end of the particles to the other. However, the maximum length connecting one end and the other end of the porous resin particles is not limited to the above range.

[0115] <10> In the above embodiment, it was illustrated that the volume percentage of voids in the bonding material 10 after the firing process is preferably 20% by volume or more and 45% by volume or less, and more preferably 32% by volume or more and 45% by volume or less. However, the volume ratio of voids in the bonding material 10 is not limited to this.

[0116] <11> The configurations disclosed in the above embodiments can be applied in combination with configurations disclosed in other embodiments, provided that no inconsistencies arise. Furthermore, the embodiments disclosed herein are illustrative, and the embodiments of the present invention are not limited thereto and can be modified as appropriate without departing from the purpose of the present invention. [Industrial applicability]

[0117] The bonding material, electrochemical module, solid oxide fuel cell, solid oxide electrolytic cell, electrochemical device, and energy system of the present invention can be fired at relatively low temperatures and can also be effectively used as a method for manufacturing the bonding material, electrochemical module, solid oxide fuel cell, solid oxide electrolytic cell, electrochemical device, energy system, and electrochemical module, enabling good oxygen supply to the air electrode (or oxygen generating electrode) under operating conditions. [Explanation of symbols]

[0118] 2: Electrode layer 4: Electrolyte layer 6: Counter electrode layer 10: Bonding material 26: Alloy components (an example of inter-cell connecting components) E: Electrochemical element M: Electrochemical Module Y: Electrochemical apparatus Z: Energy System

Claims

1. A bonding material for joining an electrochemical element and an inter-cell connecting member by firing, wherein the electrode layer, electrolyte layer, and counter electrode layer are stacked in the order described above. A bonding material comprising a mixture of a porous resin that volatilizes at temperatures between 200°C and 300°C, and a CoMn metal oxide, which is a metal oxide containing particulate Co and Mn.

2. The bonding material according to claim 1, wherein the porous resin in particulate form before volatilization has a maximum length of 1.5 μm or more and 3.0 μm or less connecting one end of the particle to the other end.

3. The bonding material according to claim 1 or 2, wherein the volume ratio of voids to the total volume is 20% by volume or more and 45% by volume or less.

4. The bonding material according to claim 1 or 2, wherein the volume ratio of voids to the total volume is 32% by volume or more and 45% by volume or less.

5. The bonding material according to claim 1 or 2, wherein the porous resin is polymethyl methacrylate.

6. A method for manufacturing an electrochemical module in which an electrochemical element in which an electrode layer, an electrolyte layer, and a counter electrode layer are stacked in the order described above and an inter-cell connecting member are joined together with a bonding material, The bonding material comprises a mixing step of mixing a porous resin that volatilizes at 200°C to 300°C and a CoMn metal oxide which is a metal oxide containing particulate Co and Mn, A method for manufacturing an electrochemical module, comprising a firing step of filling the bonding material mixed in the mixing step between the electrochemical element and the cell-to-cell connecting member and firing it.

7. The method for manufacturing an electrochemical module according to claim 6, wherein the volume percentage of the porous resin mixed as the bonding material in the mixing step is less than 24 volume percent.

8. The method for manufacturing an electrochemical module according to claim 6 or 7, wherein the volume percentage of the porous resin mixed as the bonding material in the mixing step is 12% by volume or less.

9. A method for manufacturing an electrochemical module according to claim 6 or 7, wherein the volume percentage of voids in the bonding material after the firing step has been performed is 20% by volume or more and 45% by volume or less.

10. A method for manufacturing an electrochemical module according to claim 6 or 7, wherein the volume percentage of voids in the bonding material after the firing step has been performed is 32% by volume or more and 45% by volume or less.

11. The method for manufacturing an electrochemical module according to claim 6 or 7, wherein the porous resin mixed as the bonding material in the mixing step has a maximum length of 1.5 μm or more and 3.0 μm or less between the ends of the particles.

12. An electrochemical module in which a plurality of the electrochemical elements are connected by the bonding material described in claim 1 or 2 and arranged in an assembled state.

13. A solid oxide fuel cell that generates an electric power reaction in the electrochemical elements connected by the bonding material described in claim 1 or 2.

14. A solid oxide type electrolytic cell that generates an electrolytic reaction in the electrochemical elements connected by the bonding material described in claim 1 or 2.

15. An electrochemical apparatus comprising an electrochemical module and a fuel converter as described in claim 12, and a fuel supply unit that supplies a reducing component gas from the fuel converter to the electrochemical element or the electrochemical module, or supplies a reducing component gas from the electrochemical element or the electrochemical module to the fuel converter.

16. An electrochemical apparatus comprising at least an electrochemical module as described in claim 12, 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.

17. The electrochemical apparatus according to claim 15, An energy system comprising at least a waste heat utilization unit for reusing heat discharged from the electrochemical apparatus.

18. The electrochemical apparatus according to claim 16, An energy system comprising at least a waste heat utilization unit for reusing heat discharged from the electrochemical apparatus.

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