Manufacturing method of solid oxide type cell

Abstract

To secure durability of an adhesive part of a ceramic lamination body containing a solid electrolyte layer and a metal support body supporting the lamination body while securing compactness of the solid electrolyte layer.SOLUTION: A manufacturing method of a solid oxide type cell, supported by a porous-like metal support body, contains: a high-temperature calcination step of forming a solid electrolyte layer by performing a high-temperature calcination at a temperature that exceeds a heat resistance temperature of the metal support body; a coating step of coating an adhesive paste that becomes an adhesive layer to at least one of a ceramic lamination body and the metal support body containing the solid electrolyte layer; and a low-temperature calcination step of adhering the ceramic lamination body and the metal support body obtained by being adhered via the adhesive paste by performing a low-temperature calcination at a temperature that is equal to or lower than a heatproof temperature.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to a method for manufacturing a solid oxide cell. [Background technology]

[0002] Conventionally, various methods have been proposed as a method for manufacturing a solid oxide cell in which an electrode layer and an electrolyte layer are supported on a metal support. For example, Patent Document 1 discloses a method in which an electrode layer serving as a cathode layer and an electrolyte layer are formed on a metal support and sintered, and then an electrode layer serving as an anode layer is formed on the electrolyte layer and sintered, in which the sintering is performed at a low temperature such as 900°C or 950°C to avoid excessive oxidation of the metal support.

[0003] Patent Document 2 discloses a method in which an electrode layer is formed on a metal support and then fired, a buffer layer and an electrolyte layer are formed to cover the electrode layer and then fired, and a reaction prevention layer and an electrode layer are further formed on the electrolyte layer and then fired, using a low-temperature firing method, an aerosol deposition method, a thermal spraying method, a sputtering method, etc. Whichever method is used, the method is performed at a low temperature of 1100° C. or less to suppress deterioration of the metal support.

[0004] Patent Document 3 discloses forming an air electrode on a metal support by an aerosol deposition method, forming an electrolyte layer on the air electrode by a sputtering method, and further forming a fuel electrode on the electrolyte layer by a sputtering method.

[0005] Patent Document 4 discloses a method of bonding the metal support and the power generation unit by applying a paste of crystallized glass to the metal support, placing a power generation unit, in which an anode layer, an electrolyte layer, and a cathode layer have been fired in advance at 1400° C., on the crystallized glass, and firing the power generation unit at a low temperature such as 820° C. The crystallized glass is also described as containing platinum, silver, or the like as a conductive material. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 4515028 [Patent Document 2] JP 2019-212643 A [Patent Document 3] JP 2017-195193 A [Patent Document 4] JP 2013-197067 A Summary of the Invention [Problem to be solved by the invention]

[0007] In the case of Patent Documents 1 to 3, in which an electrode layer, an electrolyte layer, etc. are formed on a metal support and then fired, the density of the electrolyte layer is likely to decrease because the firing is performed at a low temperature so as not to exceed the heat-resistant temperature of the metal support. On the other hand, in the case of Patent Document 4, in which the power generation unit is fired and then bonded to the metal support, the density of the electrolyte layer can be ensured by firing at a high temperature that exceeds the heat-resistant temperature of the metal support. However, Patent Document 4 uses crystallized glass to bond the metal support and the power generation unit, and since glass is easily cracked by temperature changes, there are concerns about durability.

[0008] A primary object of the present disclosure is to ensure the durability of the bonded portion between a ceramic laminate including a solid electrolyte layer and a metal support that supports the ceramic laminate, while ensuring the denseness of the solid electrolyte layer. [Means for solving the problem]

[0009] In order to achieve the above-mentioned main object, the present disclosure has adopted the following means.

[0010] The method of manufacturing a solid oxide cell according to the present disclosure includes the steps of: 1. A method for producing a porous metal support supported solid oxide cell, comprising the steps of: a high-temperature firing step of forming a solid electrolyte layer by firing at a temperature exceeding the heat-resistant temperature of the metal support; a coating step of coating an adhesive paste to be an adhesive layer on at least one of the ceramic laminate including the solid electrolyte layer and the metal support; a low-temperature firing step of bonding the ceramic laminate and the metal support, which are bonded together via the adhesive paste, by low-temperature firing at a temperature equal to or lower than the heat-resistant temperature; The gist of the invention is that it includes the following:

[0011] In the method for producing a solid oxide cell according to the present disclosure, the solid electrolyte layer is sintered at a high temperature above the heat-resistant temperature of the metal support, thereby ensuring the denseness of the solid electrolyte layer. Also, the ceramic laminate and the metal support, which are bonded together via the adhesive paste, are bonded by low-temperature sintering at a temperature below the heat-resistant temperature, so that no glass is used in the adhesive layer, ensuring the durability of the bonded portion. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a schematic diagram of a solid oxide cell 10. [Diagram 2] FIG. 2 is a process diagram showing an example of a method for producing the solid oxide cell 10. [Diagram 3] FIG. 2 is a schematic diagram showing the manufacturing process of the solid oxide cell 10. [Figure 4] FIG. 2 is a schematic diagram showing the manufacturing process of the solid oxide cell 10. [Diagram 5] FIG. 2 is a schematic diagram showing the manufacturing process of the solid oxide cell 10. [Figure 6] FIG. 2 is a schematic diagram showing the manufacturing process of the solid oxide cell 10. [Figure 7] FIG. 2 is an explanatory diagram showing an example of the thickness and firing temperature of each layer. [Figure 8] 1 is a cross-sectional photograph of a solid oxide cell 10. [Figure 9] FIG. 2 is an explanatory diagram showing an example of the open circuit voltage (OCV) of a solid oxide cell. [Figure 10] FIG. 1 is a schematic diagram of a modified solid oxide cell 10A. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] An embodiment of the present disclosure will be described with reference to the drawings. FIG. 1 is a schematic diagram of a solid oxide cell 10. The solid oxide cell 10 includes a ceramic laminate 11, a porous metal support 18 that supports the ceramic laminate 11, and an adhesive layer 16 that bonds (joins) the ceramic laminate 11 and the metal support 18. The ceramic laminate 11 includes a solid electrolyte layer 12, an anode layer (fuel electrode layer) 13 provided on one surface side (lower side in FIG. 1) of the solid electrolyte layer 12, and a reaction prevention layer 14 and a cathode layer (air electrode layer) 15 provided on the other surface side (upper side in FIG. 1) of the solid electrolyte layer 12. In this embodiment, the adhesive layer 16 is formed between the anode layer 13 side of the ceramic laminate 11 and the metal support 18.

[0014] Hydrogen is introduced as a fuel gas into the anode layer 13, and air is introduced into the cathode layer 15. In the cathode layer 15, oxide ions (O 2- ) are generated, and the oxide ions pass through the reaction prevention layer 14 and the solid electrolyte layer 12 and react with hydrogen in the anode layer 13 to generate electric energy. The solid oxide cell 10 can be used as an electrolysis cell in addition to being used as a fuel cell. When the solid oxide cell 10 is used as an electrolysis cell, water vapor is introduced as a fuel gas into the anode layer 13, and air is introduced into the cathode layer 15. When a power of a predetermined voltage is supplied between the terminals of the solid oxide cell 10 from a power source (not shown), the water vapor introduced into the anode layer 13 is electrolyzed in the anode layer 13 to produce hydrogen and oxygen ions (O 2- ) and the oxygen ions pass through the solid electrolyte layer 12 and the reaction prevention layer 14, generating oxygen in the cathode layer 15.

[0015] The solid electrolyte layer 12 may be made of stabilized zirconia (e.g., YSZ or ScSZ) doped with one or more rare earth elements selected from Y, Sc, Ca, etc., ceria (e.g., GDC) doped with one or more rare earth elements selected from Gd, Y, Sm, etc., or lanthanum gallate (e.g., LSGM) doped with one or more rare earth elements selected from La, Sr, Ga, Mg, Co, etc. In particular, zirconia-based ceramics are preferably used. The solid electrolyte layer 12 is generally formed by screen printing, but other methods such as a doctor blade method may also be used.

[0016] The anode layer 13 may be, for example, a mixture of a catalytic metal such as Ni or Fe exhibiting high hydrogen oxidation activity and stabilized zirconia doped with one or more rare earth elements selected from Y, Sc, Ca (e.g., NiO-ScSZ, Ni-ScSZ, NiO-YSZ, Ni-YSZ, etc.), a mixture of a catalytic metal such as Ni or Fe and ceria doped with one or more rare earth elements selected from Gd, Y, Sm, etc. (e.g., NiO-GDC, Ni-GDC, etc.), a mixture of a catalytic metal such as Ni or Fe and lanthanum gallate doped with one or more rare earth elements selected from La, Sr, Ga, Mg, Co, etc. The anode layer 13 is generally formed by screen printing, but other methods may also be used.

[0017] The cathode layer 15 may be made of a perovskite oxide containing Fe or Co. For example, La 1-x Sr x Co 1-y Fe y O 3- δ-based oxides (LSCF, x=0.4, y=0.8, δ=0, etc.) can be used. In addition, La 1-x Sr x Chief of Staff 3- δ-type oxides and Sm 1-x Sr x Chief of Staff 3-δ-type oxides and the like are also suitable. The cathode layer 15 is generally formed by screen printing, but other methods may also be used.

[0018] The reaction prevention layer 14 may be, for example, a ceria-based material (GDC) in which part of ceria Ce (+4 valence) is doped (substituted) with a rare earth cation (+3 valence). In this embodiment, the reaction prevention layer 14 formed between the solid electrolyte layer 12 and the cathode layer 15 is illustrated, but the reaction prevention layer may be formed between the solid electrolyte layer 12 and the anode layer 13. Moreover, these reaction prevention layers may not be formed.

[0019] The adhesive layer 16 may be made of a mixture of a metal or metal oxide and stabilized zirconia (e.g., NiO-ScSZ, Ni-ScSZ, NiO-YSZ, Ni-YSZ, etc.), a mixture of a metal or metal oxide and ceria (e.g., NiO-GDC, Ni-GDC, etc.), or the like, similar to the anode layer 13. In this embodiment, the anode layer 13 and the adhesive layer 16 have the same material composition, and are formed using, for example, an adhesive paste of NiO-ScSZ. Note that the adhesive layer 16 may contain particles other than NiO or Ni as a main component, as long as the adhesive paste has adhesive properties, and may be, for example, Fe2O3 or CuO. In addition, the adhesive layer 16 may not contain stabilized zirconia or ceria.

[0020] The metal support 18 serves as a support for maintaining the strength of the ceramic laminate 11 (anode layer 13, solid electrolyte layer 12, cathode layer 15, etc.) placed thereon. For the metal support 18, a material having excellent electronic conductivity, heat resistance, oxidation resistance, and corrosion resistance is used. For example, ferritic stainless steel, austenitic stainless steel, nickel alloy, etc. are used. In particular, it is preferable to use a ferritic stainless steel alloy containing manganese and chromium. This is because the thermal expansion coefficient of the metal support 18 is close to that of YSZ and GDC used as the materials for the solid electrolyte layer 12 and anode layer 13, and a thermal expansion difference with the ceramic laminate 11 is unlikely to occur in the solid oxide cell 10 operating at 600°C to 1000°C.

[0021] The metal support 18 has a plurality of through holes 18o formed therein, which penetrate from one surface (the surface on the adhesive layer 16 side) to the other surface (the surface opposite to the adhesive layer 16) in the vertical direction. The through holes 18o have the function of transmitting gas from the other surface of the metal support 18 to one surface, and a fuel gas is supplied to the anode layer 13 through the through holes 18o of the metal support 18 and the adhesive layer 16. The through holes 18o can be formed, for example, by laser or chemical etching. The metal support 18 can also be made of a porous metal having gas permeability.

[0022] Next, a manufacturing method of the solid oxide cell 10 will be described. Fig. 2 is a process diagram showing an example of the manufacturing method of the solid oxide cell 10. Figs. 3 to 6 are schematic diagrams showing the manufacturing process of the solid oxide cell 10. Fig. 7 is an explanatory diagram showing an example of the thickness of each layer and the firing temperature. In this embodiment, a temperature below the heat resistance temperature of the metal support 18 (for example, below about 1100°C) is called a low temperature, and a temperature exceeding the heat resistance temperature is called a high temperature, and firing in the low temperature range is called low-temperature firing and firing in the high temperature range is called high-temperature firing.

[0023] In the manufacture of the solid oxide cell 10, first, the solid electrolyte layer 12 is formed by high-temperature firing at a high temperature (first temperature) of 1300°C or more, for example 1500°C, which is necessary for dense film formation (step S100). In step S100, for example, a mixed powder of YSZ (for example, 3YSZ) and ScSZ (for example, 10ScSZ) is dispersed in a solvent to prepare a slurry, and the prepared slurry is used by a doctor blade method to prepare an electrolyte membrane so that the thickness after firing is about 10 to 15 μm. Then, a sheet of a predetermined size is cut out from the formed electrolyte membrane, and the solid electrolyte layer 12 is formed by high-temperature firing at, for example, 1500°C.

[0024] Next, the anode layer 13 and the reaction prevention layer 14 are formed by high-temperature firing at a high temperature (second temperature) such as 1350°C (step S110). In step S110, for example, a GDC film that becomes the reaction prevention layer 14 is screen-printed on one surface (upper surface in Fig. 1 or Fig. 3) of the solid electrolyte layer 12 so that the thickness after firing is about 3 to 5 μm. Next, the solid electrolyte layer 12 is turned upside down, and a NiO-ScSZ film that becomes the anode layer 13 is screen-printed on the other surface (lower surface in Fig. 1 or Fig. 3) of the solid electrolyte layer 12 so that the thickness after firing is about 4 to 6 μm. Then, by high-temperature firing at, for example, 1350°C, a ceramic laminate 11a in which the solid electrolyte layer 12, the anode layer 13, and the reaction prevention layer 14 are laminated is formed (see Fig. 3). Note that this is called the ceramic laminate 11a in order to distinguish it from the ceramic laminate 11 in which the cathode layer 15 is laminated. This ceramic laminate 11a can be handled as a free-standing film.

[0025] Next, an adhesive paste that will become the adhesive layer 16 is applied to the surface of the ceramic laminate 11a on the anode layer 13 side (the lower surface in FIG. 3) (step S120). In step S120, the ceramic laminate 11a in FIG. 3 is turned upside down, and a NiO-ScSZ film is applied by screen printing so that the thickness after firing is about 10 to 50 μm (see FIG. 4). Then, the ceramic laminate 11a and the metal support 18 (for example, 300 μm thick) are bonded together via the applied adhesive paste (NiO-ScSZ) (step S130, see FIG. 5), and the ceramic laminate 11a and the metal support 18 are bonded together by low-temperature firing at a low temperature (third temperature) such as 1000° C. (step S140, see FIG. 6). In step S140, the metal support 18 is fired at a temperature lower than the heat-resistant temperature, thereby suppressing deformation and oxidation of the metal support 18.

[0026] Next, the bonded ceramic laminate 11a and metal support 18 are turned upside down, and the cathode layer 15 is formed by low-temperature firing at a low temperature (fourth temperature) of, for example, 900°C (step S150). In step S150, a film of LSCF-GDC is screen-printed on the surface of the ceramic laminate 11a on the side of the reaction prevention layer 14 so that the thickness after firing is about 10 to 20 μm. Then, the cathode layer 15 is formed by low-temperature firing at, for example, 900°C. This completes the ceramic laminate 11 (see FIG. 1), and the manufacture of the solid oxide cell 10 is completed.

[0027] In this manner, in this embodiment, the ceramic laminate 11a including the solid electrolyte layer 12 sintered at high temperature is attached to the metal support 18 and bonded by low-temperature sintering, so that the solid electrolyte layer 12 having excellent density can be obtained as shown in FIG. 8. FIG. 9 is an explanatory diagram showing an example of the open circuit voltage (OCV) of a solid oxide cell. Since the solid oxide cell 10 of the embodiment has excellent density of the solid electrolyte layer 12, as shown in the figure, an open circuit voltage (1.118V) approximately equal to the theoretical open circuit voltage (1.119V) can be obtained. FIG. 9 shows the open circuit voltage (1.05V) of the solid oxide cell of Patent Document 2 as a comparative example. In Patent Document 2, each ceramic layer is formed on the metal support in sequence, and each ceramic layer is sintered at a low temperature in consideration of the heat resistance temperature of the metal, so that the density of the solid electrolyte layer cannot be ensured as in this embodiment. Therefore, the open circuit voltage in the comparative example is significantly lower than that of the embodiment.

[0028] In the manufacturing method of the solid oxide cell 10 described above, the solid electrolyte layer 12 is fired at a high temperature above the heat-resistant temperature of the metal support 18, thereby ensuring the denseness of the solid electrolyte layer 12. In addition, the ceramic laminate 11a and the metal support 18, which are bonded together via the adhesive layer 16 of the adhesive paste, are bonded by low-temperature firing at a temperature equal to or lower than the heat-resistant temperature, so that the adhesive layer 16 does not use glass, and the durability of the bonded portion can be ensured.

[0029] After the solid electrolyte layer 12 is formed, at least the anode layer 13 is laminated on one surface (lower surface in FIG. 3) of the solid electrolyte layer 12 and fired at a high temperature, and an adhesive paste is applied to the anode layer 13 side of the ceramic laminate 11a. When the adhesive paste is applied to the porous metal support 18 side, the applied adhesive paste may enter the holes, and depending on the number and size of the holes, there is a risk that the adhesiveness of the adhesive paste may decrease or the amount of adhesive paste applied may be greater than necessary. In this embodiment, by applying the adhesive paste to the anode layer 13 side, such a risk is prevented, and the ceramic laminate 11a and the metal support 18 can be more reliably bonded.

[0030] Furthermore, after bonding ceramic laminate 11a and metal support 18, cathode layer 15 is laminated on the other surface (upper side in FIG. 3) of solid electrolyte layer 12 and fired at a low temperature below the heat resistance temperature. This allows cathode layer 15 to be formed after it has been given strength (support by metal support 18). This reduces the possibility of cracking solid electrolyte layer 12 and improves the handleability of ceramic laminate 11a, compared to when cathode layer 15 is formed before bonding to metal support 18 to form ceramic laminate 11.

[0031] In addition, by applying an adhesive paste having the same material composition as the anode layer 13, the difference in thermal expansion between the anode layer 13 and the adhesive layer 16 is reduced, thereby preventing peeling between the anode layer 13 and the adhesive layer 16 and further improving the durability of the adhesive portion.

[0032] In the above-described embodiment, the adhesive paste having the same material composition as the anode layer 13 is applied, but this is not limited thereto. That is, the adhesive layer 16 may have any material composition capable of bonding the ceramic laminate 11 (11a) and the metal support 18, and an adhesive paste having a different material composition from that of the anode layer 13 may be applied. The adhesive paste may not contain glass particles and may contain at least a metal or a metal oxide. In the embodiment, the adhesive paste is applied to the anode layer 13 side of the ceramic laminate 11a, but the adhesive paste that will become the adhesive layer 16 may be applied to at least one of the ceramic laminate 11a and the metal support 18, for example, by applying the adhesive paste to the metal support 18.

[0033] In the embodiment, the ceramic laminate 11a and the metal support 18 are bonded together and then fired (adhered) at a low temperature, and then the cathode layer 15 is printed and fired at a low temperature, but this is not limited to the above. For example, the ceramic laminate 11a and the metal support 18 may be bonded together, the cathode layer 15 may be printed, and then fired at a low temperature. Alternatively, the cathode layer 15 may be fired before bonding (adhering) the ceramic laminate 11a and the metal support 18 together. That is, the ceramic laminate 11 may be completed, and then bonded to the metal support 18. In this case, the cathode layer 15 is not limited to being fired at a low temperature, and may be fired at a high temperature, for example, at 1100°C.

[0034] The configuration of the solid oxide cell 10 is not limited to that shown in Fig. 1, and may be as shown in a modified example of Fig. 10. In the solid oxide cell 10A of the modified example of Fig. 10, a seal portion 19 is formed to seal the sides of the anode layer 13 and the adhesive layer 16. For example, the seal portion 19 may be formed by applying (printing) an adhesive paste that will become the adhesive layer 16 so as to surround the anode layer 13 and the adhesive layer 16 (adhesive paste) in a ring shape, and then firing the seal portion 19 and the adhesive layer 16 at a low temperature at the same time, for example, in S140.

[0035] The solid oxide cell 10 of the present disclosure includes a ceramic laminate 11 including a solid electrolyte layer 12 having a thickness of 20 μm or less (for example, 10 to 15 μm), a porous metal support 18, and an adhesive layer 16 including a metal or metal oxide and bonding the ceramic laminate 11 and the metal support 18. The ceramic laminate 11 may have a total thickness of 50 μm or less. The adhesive layer 16 is formed by sintering an adhesive paste including a metal or metal oxide, and includes at least one metal or metal oxide selected from Ni, Fe, and Cu. The adhesive layer 16 may have the same material composition as the anode layer 13 included in the ceramic laminate 11.

[0036] The correspondence between the main elements of the embodiment and the main elements of the present disclosure described in the section on Means for Solving the Problems will be described below. Step S100 of the method for producing a solid oxide cell of the embodiment corresponds to the "high-temperature firing step" of the present disclosure, step S120 corresponds to the "coating step", and step S140 corresponds to the "low-temperature firing step". Step S110 corresponds to the "high-temperature firing step", and step S150 corresponds to the "low-temperature firing step".

[0037] In addition, the correspondence between the main elements of the embodiment and the main elements of the present disclosure described in the Means for Solving the Problem column does not limit the elements of the present disclosure described in the Means for Solving the Problem column, since the embodiment is an example for specifically explaining the form for implementing the present disclosure described in the Means for Solving the Problem column. In other words, the interpretation of the present disclosure described in the Means for Solving the Problem column should be made based on the description in that column, and the embodiment is merely a specific example of the present disclosure described in the Means for Solving the Problem column.

[0038] The above describes the form for implementing the present disclosure using embodiments, but the present disclosure is not limited to these embodiments in any way, and it goes without saying that the present disclosure can be implemented in various forms without departing from the gist of the present disclosure. [Industrial Applicability]

[0039] The present disclosure is applicable to the solid oxide cell manufacturing industry and the like. [Explanation of symbols]

[0040] 10, 10A solid oxide cell, 11, 11a ceramic laminate, 12 solid electrolyte layer, 13 anode layer, 14 reaction prevention layer, 15 cathode layer, 16 adhesive layer, 18 metal support, 18o through hole, 19 seal portion.

Claims

1. 1. A method for producing a porous metal support supported solid oxide cell, comprising the steps of: a high-temperature firing step of forming a solid electrolyte layer by firing at a temperature exceeding the heat-resistant temperature of the metal support; a coating step of coating an adhesive paste to be an adhesive layer on at least one of the ceramic laminate including the solid electrolyte layer and the metal support; a low-temperature firing step of bonding the ceramic laminate and the metal support, which are bonded together via the adhesive paste, by low-temperature firing at a temperature equal to or lower than the heat-resistant temperature; A method for producing a solid oxide cell comprising the steps of:

2. In the high-temperature firing step, after forming the solid electrolyte layer, an anode layer is laminated on one surface side of the solid electrolyte layer, and the anode layer is fired at a high temperature exceeding the heat-resistant temperature to form the ceramic laminate; In the coating step, the adhesive paste is coated on the anode layer side of the ceramic laminate. A method for producing a solid oxide cell according to claim 1.

3. In the low-temperature firing step, the ceramic laminate and the metal support are bonded together, and then a cathode layer is laminated on the other surface side of the solid electrolyte layer, followed by low-temperature firing at a temperature equal to or lower than the heat-resistant temperature. A method for producing a solid oxide cell according to claim 2.

4. In the coating step, the adhesive paste having the same material composition as the anode layer is coated. A method for producing a solid oxide cell according to claim 2.

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