Electric cell manufacturing method and electric cell

Abstract

The edges of the metal support layer must be densified to an extent that gas leakage can be prevented without destroying the electrolyte layer. [Solution] A method for manufacturing an electric cell includes the steps of: preparing a laminate having an electrolyte layer, a cathode electrode layer, an anode electrode layer, and a pair of metal support layers, each of which has a porous structure; filling an end of each metal support layer with a filler; and pressing the end of each metal support layer to densify it. Equipped with.

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing an electric cell. [Background technology]

[0002] Solid oxide fuel cells (SOFCs) and solid oxide electrolysis cells (SOECs) are devices that have roughly the same configuration. In this specification, SOFCs and SOECs are collectively referred to as "electric cells."

[0003] A double-sided metal-supported device is known as an electric cell. A double-sided metal-supported electric cell is an electric cell that uses a pair of metal support layers. Specifically, a double-sided metal-supported electric cell has an electrolyte layer, a cathode electrode layer, an anode electrode layer, and a pair of metal support layers. The cathode electrode layer and the anode electrode layer are arranged to sandwich the electrolyte layer. The pair of metal support layers are arranged on the outside of the cathode electrode layer and the anode electrode layer. The pair of metal support layers have a porous structure that allows the anode gas and the cathode gas to pass through, respectively.

[0004] During operation, gas is transferred between each electrode layer and the outside through each metal support layer. Gas passing through each metal support layer may leak from the side. Densifying the ends of each metal support layer is one way to prevent gas leakage from the side.

[0005] In relation to the above, Patent Document 1 (JP 2010-534901 A) describes a fuel cell having a plate manufactured by powder metallurgy, the plate being manufactured into a single plate and having a porous substrate region, on top of which a layer of electrochemically active cells is attached, and further the plate having an airtight end region provided with a gas passage through which gas passes. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Special Publication No. 2010-534901 Summary of the Invention [Problem to be solved by the invention]

[0007] The present inventors have considered pressing the edges of each metal support layer to densify them. However, pressing alone may not be enough to prevent gas leakage. Increasing the pressing load may be considered to reliably prevent gas leakage, but increasing the pressing load may destroy the electrolyte layer.

[0008] Therefore, an object of the present invention is to provide a technique that can densify the end portion of a metal support layer to an extent that gas leakage can be prevented without destroying the electrolyte layer. [Means for solving the problem]

[0009] In one aspect, the present invention is a method for manufacturing an electric cell, such as a SOFC or SOEC, comprising the steps of: preparing a stack having an electrolyte layer, a cathode electrode layer, an anode electrode layer, and a pair of metal support layers, each having a porous structure; pressing edges of each metal support layer to densify them; and filling the edges of each metal support layer with a filler. [Effects of the Invention]

[0010] According to the present invention, a technique is provided that can densify the edge of the metal support layer to an extent that gas leakage can be prevented without destroying the electrolyte layer. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a cross-sectional view that schematically illustrates an electric cell 1. [Figure 2]FIG. 2 is a flow chart that schematically shows a method for manufacturing an electric cell according to this embodiment. [Figure 3] FIG. 3 is a flowchart showing a specific example of a method for manufacturing an electric cell according to this embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, a method for manufacturing an electric cell according to an embodiment of the present invention will be described with reference to the drawings. As described above, in this specification, the term "electric cell" collectively refers to SOFCs and SOECs. In this embodiment, the method for manufacturing an electric cell will be described using an SOFC as an example. However, the electric cell according to this embodiment may also be used as an SOEC.

[0013] (1) Electric cell configuration First, the configuration of an electric cell 1 manufactured by a manufacturing method according to this embodiment will be described. Fig. 1 is a cross-sectional view that schematically shows the electric cell 1. Fig. 1 shows an end of the cell structure of the electric cell 1.

[0014] As shown in FIG. 1, the electric cell 1 has an electrolyte layer 2, a pair of electrode layers 3 (a cathode electrode layer 3-1 and an anode electrode layer 3-2), and a pair of metal support layers 4 (a cathode metal support layer 4-1 and an anode metal support layer 4-2). These are stacked in the stacking direction. Specifically, the cathode electrode layer 3-1 and the anode electrode layer 3-2 are arranged so as to sandwich the electrolyte layer 2. The cathode metal support layer 4-1 and the anode metal support layer 4-2 are arranged on the outer sides of the cathode electrode layer 3-1 and the anode electrode layer 3-2.

[0015] The electrolyte layer 2 is configured to be oxide ion conductive but gas impermeable. For example, the electrolyte layer 2 is formed of dense ceramics. Examples of ceramics include solid oxide ceramics. Examples of solid oxide ceramics include zirconia-containing materials. Examples of zirconia-containing materials include stabilized zirconia doped with yttria, neodymium oxide, samarium, gadolinium, scandium, etc. The thickness of the electrolyte layer 2 is, for example, 0.5 to 20 μm, preferably 1 to 10 μm.

[0016] The cathode electrode layer 3-1 is a portion that converts oxygen molecules contained in the cathode gas into oxide ions. For example, the cathode electrode layer 3-1 has porous conductive ceramics and a cathode catalyst supported on the conductive ceramics. The conductive ceramics are not particularly limited, but examples thereof include scandia-stabilized zirconia (SSZ). The thickness of the cathode electrode layer 3-1 is, for example, 0.3 to 50 μm, preferably 0.5 to 30 μm.

[0017] The anode electrode layer 3-2 is a part that reacts fuel such as hydrogen with oxide ions to generate electrons. The anode electrode layer 3-2 can also have a configuration similar to that of the cathode electrode layer 3-1. For example, the anode electrode layer 3-2 has porous conductive ceramics and an anode catalyst supported on the conductive ceramics. Examples of conductive ceramics include scandia-stabilized zirconia (SSZ). The thickness of the anode electrode layer 3-2 is, for example, 0.3 to 50 μm, preferably 0.5 to 30 μm.

[0018] A pair of metal support layers 4 are provided to support the electric cell 1. Each metal support layer 4 has a porous structure. For example, each metal support layer 4 is made of SUS.

[0019] Specifically, each metal support layer 4 has a central portion 5 and end portions 6 .

[0020] The central portion 5 is configured to be gas permeable.

[0021] On the other hand, the end portion 6 is configured to block gas. The end portion 6 has a denser structure than the central portion 5. As will be described later, the end portion 6 is a portion where the metal support layer is compressed by pressing. Therefore, the density of the metal support at the end portion 6 is higher than that at the central portion 5. The metal support here refers to the density of the metal material that forms the skeleton of the metal support layer. Furthermore, the thickness of the end portion 6 is smaller than that of the central portion 5.

[0022] The pores at the end portion 6 are filled with a filler. The filler preferably contains metal particles. The metal particles may be made of the same material as the constituent material of each electrode layer 3, such as SSZ.

[0023] There is no particular limitation on the thickness of each metal support layer 4. For example, the thickness of each metal support layer 4 in the central portion 5 is 50 to 1000 μm, and preferably 100 to 500 μm.

[0024] The above is a schematic configuration of the electric cell 1 according to this embodiment. During operation of this electric cell 1, a cathode gas (oxygen-containing gas) is supplied to the cathode electrode layer 3-1 via the cathode metal support layer 4-1. An anode gas (fuel gas: for example, a hydrogen-containing gas) is supplied to the anode electrode layer 3-2 via the anode metal support layer 4-2. Then, in each electrode layer 3 (3-1 and 3-2), a reaction as a fuel cell proceeds, and power is generated. At this time, because the end 6 of each metal support layer 4 is configured to block gas, the gas passing through each metal support layer 4 moves along the stacking direction and does not leak from the side.

[0025] As mentioned above, the electric cell may be an SOEC. In this case, during operation, water vapor is supplied to the cathode electrode layer 3-1 via the cathode metal support layer 4-1, and hydrogen and oxygen ions are produced by an electrochemical reaction. Meanwhile, in the anode electrode layer 3-2, oxygen is produced from the oxygen ions via an electrochemical reaction, and the oxygen is extracted via the anode metal support layer 4-2. This causes water to be electrolyzed.

[0026] (2) Manufacturing method of electric cell Next, a method for manufacturing an electric cell having the above-described structure will be described. In this embodiment, a method for forming the end portion 6 of the metal support layer 4 is devised.

[0027] FIG. 2 is a flowchart that schematically illustrates a method for manufacturing an electric cell according to this embodiment. In summary, the manufacturing method according to this embodiment includes a step of preparing a stack (step S1), a step of filling a filler (step S2), and a step of pressing (step S3). In the step of preparing a stack (S1), a stack is prepared that includes an electrolyte layer, a cathode electrode layer, an anode electrode layer, and a pair of metal support layers. In the step of filling a filler (S2), a slurry containing the filler is supplied, thereby filling the filler into the ends of each metal support layer. In the step of pressing (S3), the ends of each metal support layer are pressed to densify them.

[0028] According to this manufacturing method, since the filler is filled, the end portions of each metal support layer can be sufficiently densified even with a low pressing load. Since the pressing load can be reduced, destruction of the electrolyte layer can be prevented. That is, the end portions of each metal support layer can be densified to a degree that prevents gas leakage without destroying the electrolyte layer.

[0029] The above is an outline of this embodiment. Next, the manufacturing method according to this embodiment will be described in detail with more specific examples.

[0030] Fig. 3 is a flowchart showing a specific example of a method for manufacturing an electric cell according to this embodiment. The method for manufacturing an electric cell shown in Fig. 3 includes a laminate-forming step (S1), a filling step (S2), and a pressing step (S3), as well as a firing step (S4) and a catalyst impregnation step (S5). The filling step and the pressing step (S2+S3) are performed at any timing after the laminate-forming step (S1).

[0031] Each step will be described in more detail below.

[0032] Step S1: Creating a laminate First, a laminate is prepared. The method for preparing the laminate is not particularly limited. For example, green sheets for each layer included in the electric cell are prepared. The green sheets can be obtained, for example, by preparing a slurry containing the constituent materials of each layer and applying it to a substrate. Next, the green sheets for each layer are stacked and integrated. For example, multiple green sheets can be integrated using warm isostatic pressing (WIP). This results in a laminate having an electrolyte layer, a pair of electrode layers, and a pair of metal support layers.

[0033] When producing the laminate, a pore-forming material is used to obtain a porous structure. Specifically, a sheet containing a particulate pore-forming material is produced as a green sheet for forming each metal support layer. After lamination, the pore-forming material is removed from the laminate by a degreasing process or the like. This results in the formation of a porous structure in the metal support layer.

[0034] Step S4: Firing The laminate is then fired at a firing temperature of, for example, 900 to 1400°C, and preferably 1100 to 1300°C.

[0035] Step S5: Catalyst impregnation After the firing step (S4), each electrode layer is impregnated with a slurry containing a catalyst. Specifically, the anode electrode layer is impregnated with a slurry containing an anode catalyst, and the cathode electrode layer is impregnated with a slurry containing a cathode catalyst. After impregnation, each electrode layer is heat-treated.

[0036] Steps S2+S3: Filling and pressing As mentioned above, the filling step and the pressing step (S2+S3) are performed in the laminate production step (S1). The filling and pressing steps (S2+S3) can be performed at any timing after the calcination step (S4). Preferably, the filling and pressing steps (S2+S3) are performed after the calcination step (S4). For example, the filling and pressing steps (S2+S3) can be performed between the calcination step (S4) and the catalyst impregnation step (S5). Alternatively, the filling and pressing steps (S2+S3) can be performed after the catalyst impregnation step (S6).

[0037] In the filling step (S2), as described above, a slurry containing a filler is supplied. Preferably, after supplying the slurry, the edge of the metal support layer is fired. This firing is a step different from the firing in step S4. The firing temperature is, for example, 900 to 1400°C, preferably 1100 to 1300°C. This fixes the filler in the pores of the edge.

[0038] The particle size of the filler (average particle size: number average of equivalent circle diameters determined by image analysis using a microscope) is preferably 10% or less of the particle size of the pore-forming material used in step S1. If a filler having such a particle size is used, the filler will be densely packed into the pores at the edge of the metal support layer. Therefore, gas leakage can be more reliably prevented.

[0039] In the pressing step (S3), for example, a molding die is used to press the metal support layer so that the end portions of the metal support layer are compressed in the stacking direction, thereby densifying the metal support layer.

[0040] The filling step and the pressing step (S2+S3) may be performed at multiple times, or may be performed only once.

[0041] The order of the filling step (S2) and the pressing step (S3) is not particularly limited. As shown in Fig. 2, the filling step (S2) may be performed before the pressing step (S3). On the other hand, the filling step (S2) may be performed after the pressing step (S3).

[0042] If the filling step (S2) is performed before the pressing step (S3), the molding load in the pressing step (S3) can be more easily reduced, thereby more reliably preventing the electrolyte layer from being destroyed.

[0043] On the other hand, when the filling step (S2) is performed after the pressing step (S3), the edges of the metal support are in a relatively dense state, making it difficult for the filled filler to flow out from the edges, which reduces the amount of filler used and the cost spent on the filler.

[0044] The filling step (S2) and the pressing step (S3) may be performed at different times. For example, the filling step (S2) may be performed between the calcining step (S4) and the catalyst impregnation step (S5), and the pressing step (S3) may be performed after the catalyst impregnation step (S5).

[0045] As mentioned above, the timing of the filling step (S2) and the pressing step (S3) is not particularly limited. However, if calcination is performed in the filling step (S2), it is preferable that the filling step (S2) be performed before the catalyst impregnation step (S5). If the laminate is calcined after the catalyst impregnation step (S5), the catalyst may be deteriorated. If the filling step (S2) is performed before the catalyst impregnation step (S5), calcination is not required after the catalyst impregnation step (S5), and therefore catalyst deterioration can be avoided.

[0046] [Note] Representative configurations included in the present invention and their effects are summarized below as appendices.

[0047] (Appendix 1) A method for manufacturing an electric cell that is an SOFC or an SOEC, the method comprising: a step (S1) of preparing a laminate having an electrolyte layer 2, a cathode electrode layer 3-1, an anode electrode layer 3-2, and a pair of metal support layers 4, each of which has a porous structure; a step (S2) of filling an end of each metal support layer with a filler by supplying a slurry containing a filler; and a step (S3) of pressing the end of each metal support layer to densify it.

[0048] According to this method, the filler is filled into the edge portion, so that the edge portion can be sufficiently densified while reducing the molding load during pressing, thereby preventing destruction of the electrolyte layer and enabling the edge portion to be sufficiently densified.

[0049] (Appendix 2) 10. The manufacturing method of claim 1, wherein the filling step (S3) comprises preparing a slurry containing a filler and supplying the slurry to the end of each metal support layer.

[0050] This method allows the end portions to be filled with filler.

[0051] (Appendix 3) 3. The method of claim 1 or 2, wherein the filler comprises metal particles.

[0052] (Appendix 4) 4. The manufacturing method according to any one of Supplementary Notes 1 to 3, wherein the filling step (S2) is carried out before the pressing step (S3).

[0053] According to this method, the filler is supplied in a state where the end 6 is sparse, making it easier to fill with the filler.

[0054] (Appendix 5) 4. The manufacturing method according to any one of Supplementary Notes 1 to 3, wherein the filling step (S2) is carried out after the pressing step (S3).

[0055] According to this method, the filler is supplied to the end 6 in a dense state, so that the filler once supplied to the end is less likely to leak out. This makes it possible to reduce the amount of filler used and cut manufacturing costs.

[0056] (Appendix 6) A manufacturing method according to any one of Appendices 1 to 5, wherein the step (S1) of preparing the laminate comprises the steps of forming a layer containing a particulate pore-forming material as each metal support layer 4, and removing the pore-forming material from each metal support layer 4 to form a porous structure in each metal support layer 4, and the particle diameter of the filler is 10% or less of the particle diameter of the pore-forming material.

[0057] According to this method, the holes at the end can be densely filled with the filler, and gas leakage can be prevented more reliably.

[0058] (Appendix 7) The electric cell (1) is an SOFC or SOEC, and comprises a laminate having an electrolyte layer (2), a cathode electrode layer (3-1), an anode electrode layer (3-2), and a pair of metal support layers (4), each of the pair of metal support layers (4) having a porous structure, each metal support layer (4) having a central portion (5) and an end portion (6), the end portion (6) being denser than the central portion (5), and the pores at the end portions being filled with a filler.

[0059] With this configuration, it is possible to obtain an electric cell in which the end portions of the metal support layer are densified to an extent that gas leakage can be prevented while preventing destruction of the electrolyte layer. [Explanation of symbols]

[0060] 1 Electrical cell, 2 Electrolyte layer, 3 Electrode layer, 3-1 Cathode electrode layer, 3-2 Anode electrode layer, 4 Metal support layer, 4-1 Cathode metal support layer, 4-2 Anode metal support layer, 5 Center, 6 Edge

Claims

1. 1. A method for manufacturing an electric cell, which is a SOFC or SOEC, comprising: A step of preparing a laminate having an electrolyte layer, a cathode electrode layer, an anode electrode layer, and a pair of metal support layers, each of the pair of metal support layers having a porous structure; filling the ends of each metal support layer with a filler by supplying a slurry containing the filler; pressing the ends of each of the metal support layers to densify them; Equipped with Method for manufacturing an electric cell.

2. The method of claim 1, The filler contains metal particles. Manufacturing method.

3. The manufacturing method according to claim 1 or 2, The filling step is performed before the pressing step. Manufacturing method.

4. The manufacturing method according to claim 1 or 2, The filling step is performed after the pressing step. Manufacturing method.

5. 3. The method of claim 1 or 2, The step of preparing the laminate includes: forming a layer containing a particulate pore-forming material as each of the metal support layers; and forming a porous structure in each of the metal support layers by removing the pore-forming material from each of the metal support layers, The particle diameter of the filler is 10% or less of the particle diameter of the pore-forming material. Manufacturing method.

6. 1. An electric cell that is a SOFC or SOEC, a laminate including an electrolyte layer, a cathode electrode layer, an anode electrode layer, and a pair of metal support layers; Equipped with each of the pair of metal support layers has a porous structure; each metal support layer having a center portion and an end portion; the density of the metal support is higher at the end portion than at the central portion; The pores at the end are filled with a filler. Electric cell.

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