Method for manufacturing anode for fuel cell and laminated structure for fuel cell anode manufactured by same

Abstract

The invention discloses a manufacturing method of an anode for a fuel cell. The manufacturing method includes: a plurality of first green body manufacturing step of forming a first slurry containing YSZ, nickel, and a pore-forming agent to manufacture a plurality of first green bodies stretched in one direction; a second green body manufacturing step of molding a second slurry containing YSZ and nickel to manufacture a second green body stretched in one direction; a first intermediate laminate manufacturing step for manufacturing a first intermediate laminate by alternately laminating the plurality of first green bodies so that the stretching directions intersect, and then laminating the second green bodies so that the stretching direction intersects the stretching direction of the top first green body; and a pressure sintering step in which the first intermediate laminate is subjected to pressure sintering.

Description

Technical Field

[0001] This invention relates to a method for manufacturing an anode for a fuel cell and a laminated structure for fuel cell anodes manufactured using the same. Background Technology

[0002] A solid oxide fuel cell (SOFC) is a device that converts the chemical energy of fuel into electrical energy through an electroreaction. Based on the structural support layer, SOFCs can be divided into electrolyte-supported and electrode-supported types. Fuel electrode-supported SOFCs typically consist of a cathode, electrolyte, anode functional layer, and support layer.

[0003] To ensure high strength, the anode support layer can be stacked with the anode support green sheet, but this method has limitations. Furthermore, the anode support green sheet becomes anisotropic during casting according to the forming direction, resulting in different shrinkage rates when sintered longitudinally and laterally according to the forming direction. An improved solution is needed to overcome these problems and obtain sintered bodies with uniform size.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Korean Patent Publication No. 10-2017-0010625 Summary of the Invention

[0007] The problem the invention aims to solve

[0008] One object of the present invention is to provide a method for manufacturing an anode for a fuel cell, wherein the manufacturing method controls the sintering behavior by alternating multiple green blanks, thereby enabling the manufacture of uniform single cells.

[0009] Another object of the present invention is to provide a laminated structure for a fuel cell anode that ensures the high strength of the aforementioned structure.

[0010] means for solving problems

[0011] To achieve the aforementioned objective, the present invention provides a method for manufacturing an anode for a fuel cell, the method comprising: a plurality of first green blank manufacturing steps, wherein a first slurry comprising YSZ, nickel and a pore-forming agent mixed in a first weight ratio is shaped to manufacture a plurality of first green blanks stretched in one direction; a second green blank manufacturing step, wherein a second slurry comprising YSZ and nickel mixed in a second weight ratio is shaped to manufacture a second green blank stretched in one direction; a first intermediate laminate manufacturing step, wherein the plurality of first green blanks are alternately laminated in a manner with intersecting stretching directions, and then, based on this, a second green blank is laminated in a manner with a stretching direction intersecting the stretching direction of the top first green blank to manufacture a first intermediate laminate; and a pressure sintering step, wherein the first intermediate laminate is pressure sintered.

[0012] In addition, the present invention provides a method for manufacturing an anode for a fuel cell, the method comprising: a plurality of first green blank manufacturing steps, wherein a first slurry comprising YSZ, nickel and a pore-forming agent mixed in a first weight ratio is formed to manufacture a plurality of first green blanks stretched in one direction; an alternating lamination step, wherein the plurality of first green blanks are alternately laminated in a manner with the stretching directions intersecting; a second intermediate laminate manufacturing step, wherein a second slurry comprising YSZ and nickel mixed in a second weight ratio is coated on the laminated first green blanks to manufacture a second intermediate laminate; and a pressure sintering step, wherein the second intermediate laminate is subjected to a pressure sintering step.

[0013] In addition, the present invention provides a laminated structure for a fuel cell anode, comprising: a laminated body for a fuel electrode support, formed by alternatingly stacking a plurality of first green blanks in a cross-stretching direction, wherein the plurality of first green blanks are manufactured by stretching in one direction using a first slurry comprising YSZ, nickel and a pore-forming agent mixed in a first weight ratio; and a second green blank, manufactured by stretching in one direction using a second slurry comprising YSZ and nickel mixed in a second weight ratio, and stacked on the top first green blank in a stretching direction that crosses the stretching direction of the top first green blank.

[0014] Invention Effects

[0015] According to the present invention, the method for manufacturing the anode for fuel cells can cross-layer green blanks, and during sintering, uniform shrinkage occurs, thereby homogenizing the size of the single cell.

[0016] In addition, the laminated structure for fuel cell anodes of the present invention can have excellent strength. Attached Figure Description

[0017] Figure 1 This is a flowchart illustrating a method for manufacturing an anode for a fuel cell according to an embodiment of the present invention.

[0018] Figure 2 It is a diagram illustrating the layering of green bodies.

[0019] Figure 3 This is a flowchart illustrating a method for manufacturing an anode for a fuel cell according to another embodiment of the present invention.

[0020] Figure 4 These are images observing the microstructure of Example 2.

[0021] Figure 5 These are the results of the three-point bending strength test of Example 2 and Comparative Example 2. Detailed Implementation

[0022] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The present invention can be modified and has various forms, and specific embodiments are shown in the accompanying drawings and described in detail herein. However, this is not to limit the present invention to the specific forms disclosed, but should be understood to include all modifications, equivalents, and substitutions contained within the spirit and technical scope of the present invention. In describing the drawings, similar reference numerals are used for similar constituent elements. In the drawings, to ensure clarity of the invention, the dimensions of structures are shown enlarged compared to actual dimensions.

[0023] The terms "first," "second," etc., can be used to describe various constituent elements, but the constituent elements are not limited to those terms. These terms are used only to distinguish one constituent element from another. For example, without departing from the scope of this invention, a first constituent element may be named a second constituent element, and similarly, a second constituent element may also be named a first constituent element.

[0024] The terminology used in this application is for illustrative purposes only and is not intended to limit the invention. Unless the context clearly indicates otherwise, a single quantity includes multiple quantities. In this application, terms such as "comprising" or "having" are used to specify the presence of features, numbers, steps, actions, constituent elements, components, or combinations thereof described in the specification, and should be understood to not preclude the presence or possibility of one or more other features, numbers, steps, actions, constituent elements, components, or combinations thereof.

[0025] On the other hand, unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Terms commonly used and identical to those defined in dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant art, and are not to be interpreted as having an ideal or overly formal meaning unless explicitly defined herein.

[0026] Figure 1This is a flowchart illustrating a method for manufacturing an anode for a fuel cell according to an embodiment of the present invention.

[0027] Reference Figure 1 A method for manufacturing an anode for a fuel cell according to an embodiment of the present invention may include: step S110, molding a first slurry containing YSZ, nickel and a pore-forming agent to manufacture a plurality of first green blanks stretched in one direction; step S120, molding a second slurry containing YSZ and nickel to manufacture a second green blank stretched in one direction; step S130, alternately stacking the plurality of first green blanks in a manner with intersecting stretching directions, and then, based on this, stacking the second green blanks in a manner with stretching directions intersecting the stretching direction of the top first green blank to manufacture a first intermediate laminate; and step S140, pressurizing and sintering the first intermediate laminate.

[0028] In step S110 of manufacturing the first green body, the weight ratio of NiO to YSZ in the first slurry can be (1.5~2):1. The first green body is used to manufacture an anode support, and in order to improve the conductivity of the anode support, the first slurry can have a relatively high Ni content.

[0029] In one embodiment, the first slurry may contain about 15% to 25% by volume of the pore-forming agent. For example, the first slurry may contain about 20% by volume of the pore-forming agent, which may comprise one selected from the group consisting of polymethyl methacrylate (PMMA), activated carbon, carbon black, graphite, and starch. With the first green compact containing the pore-forming agent, pores that allow fluid (e.g., fuel gas) to move can be formed within the anode support for the fuel cell.

[0030] In one embodiment, the first slurry is prepared as follows: after mixing NiO, YSZ, and a pore-forming agent, it is dispersed in a solvent, and a binder is added thereto. The binder can be used alone or in combination with two or more binders, such as polyvinyl alcohol (PVA) binders, methylcellulose (MC) binders, sodium carboxymethylcellulose (CMC) binders, etc.

[0031] In one embodiment, the first green body may be manufactured by processes such as extrusion molding or tape casting using the first slurry, but is not limited thereto.

[0032] In one embodiment, the thickness of the first green blank can be from 220 μm to 240 μm.

[0033] In step S120 of manufacturing the second green compact, the weight ratio of NiO to YSZ in the second slurry can be (1-1.5):1. The second green compact is used to manufacture an anode functional layer disposed adjacent to the solid oxide electrolyte. The second slurry may not contain a pore-forming agent to form a further increased triple point (gas / electrolyte / electrode) in the anode functional layer. The anode functional layer may contain a lower Ni content than the first slurry to give it lower conductivity than the anode support layer.

[0034] In one embodiment, the second slurry is prepared as follows: after mixing NiO and YSZ, it is dispersed in a solvent, and a binder is added thereto. The binder is the same as described above, so further details are omitted.

[0035] In one embodiment, the thickness of the second green blank may be from 10 μm to 14 μm.

[0036] In step S130 of manufacturing the first intermediate laminate, as Figure 2 As shown, two or more first green blanks can be alternately stacked in a cross-stretching manner, and then the second green blank can be stacked in a cross-stretching manner on top of them.

[0037] In the pressure sintering step S140, the sintering can be carried out in an air atmosphere at a temperature of 1300°C to about 1500°C. During the pressure sintering of the first intermediate laminate, pores corresponding to the pore-forming agent are formed inside the first green body, and the first and second green bodies can be bonded together. As a result, the first intermediate laminate can be converted into an anode for a fuel cell formed of Ni-YSZ cermet.

[0038] As an example, when the first green blank and the second green blank are stacked in a cross-stretching manner, uniform X-axis and Y-axis shrinkage of the first green blank and the second green blank can be induced during the pressure sintering process, resulting in the manufacture of an anode for a fuel cell with improved strength.

[0039] Figure 3 This is a flowchart illustrating a method for manufacturing an anode for a fuel cell according to another embodiment of the present invention.

[0040] Reference Figure 3Another embodiment of the present invention provides a method for manufacturing an anode for a fuel cell, which may include: step S150, molding a first slurry containing YSZ, nickel and a pore-forming agent to manufacture a plurality of first green blanks stretched in one direction; step S160, alternately stacking the plurality of first green blanks in a cross-stretching direction; step S170, coating the stacked first green blanks with a second slurry containing YSZ and nickel to manufacture a second intermediate laminate; and step S180, pressurizing and sintering the second intermediate laminate.

[0041] Step S150 of manufacturing the first green blank and reference Figure 1 The step S110 of manufacturing the first green blank in the described method for manufacturing the anode for a fuel cell is actually the same, so its detailed description is omitted.

[0042] In step S170 of manufacturing the second intermediate laminate, a second slurry is applied to the first green preform, which is alternately laminated in a cross-stretching manner, to form a second slurry layer corresponding to the anode functional layer. There are no particular limitations on the method for forming the second slurry layer on the first green preform. For example, the second slurry layer can be formed by barcoating the second slurry onto the first green preform.

[0043] In the pressure sintering step S180, the sintering can be carried out in an air atmosphere at a temperature of 1300°C to about 1500°C. During the pressure sintering of the second intermediate laminate, pores corresponding to the pore-forming agent are formed inside the first green body, and the first and second green bodies can be bonded together. As a result, the second intermediate laminate can be converted into an anode for a fuel cell formed of Ni-YSZ cermet.

[0044] In one embodiment, the difference between the longitudinal length and the transverse length in the tensile direction of the first or second intermediate laminate can be less than 0.75% of the length of the first or second intermediate laminate. If the difference in length exceeds about 0.75%, anisotropy is formed in the laminate for the fuel electrode support, which may be detrimental to its application in fuel cells.

[0045] The fuel cell anode stacked structure of the present invention may include the aforementioned first intermediate stack or second intermediate stack.

[0046] As one embodiment, the fuel cell anode laminate may include: a fuel electrode support laminate, formed by alternatingly stacking a plurality of first green blanks in a cross-stretching direction, the plurality of first green blanks being manufactured by stretching in one direction using a first slurry containing YSZ, nickel and a pore-forming agent; and a second green blank, manufactured by stretching in one direction using a second slurry containing YSZ and nickel, and stacked on the top first green blank in a stretching direction that intersects with the stretching direction of the top first green blank.

[0047] In one embodiment, the pore-forming agent, the first slurry and the second slurry, the first green body and the second green body are respectively compared with a reference. Figure 1 The pore-forming agent, the first slurry and the second slurry, the first green body and the second green body described in the manufacturing method are actually the same, so their details are omitted.

[0048] The present invention will now be described in detail with reference to embodiments to aid in understanding. However, the following embodiments are merely illustrative and the scope of the invention is not limited to these embodiments. The embodiments of the present invention are provided to provide a more complete explanation of the invention to those skilled in the art.

[0049] <Examples 1 to Examples 5>

[0050] A first slurry was prepared by mixing NiO and YSZ in a solvent at a weight ratio of (1.5–2):1, followed by the addition of approximately 20% by volume of a pore-forming agent. The first slurry was then used to fabricate an anode support layer green body by tape casting. The anode support layer green bodies were fabricated in the quantities shown in Table 1 below. A second slurry was prepared by mixing NiO and YSZ in a solvent at a weight ratio of (1–1.5):1. The second slurry was then used to fabricate an anode functional layer green body by tape casting. Multiple anode support layer green bodies were stacked with their stretching directions intersecting each other. Anode functional layer green bodies were stacked with their stretching directions intersecting the top surface stretching directions of the stacked anode support layer green bodies. The fuel electrode was fabricated by pressure sintering the stacked structure in an air atmosphere at approximately 1300°C to 1500°C. The sintered layer consisted of four anode support layers and one anode functional layer.

[0051] Table 1

[0052] Total sintered layer Example 1 3 Example 2 5 Example 3 7 Example 4 9 Example 5 11

[0053] <Comparative Examples 1 to 5>

[0054] The fuel electrode was manufactured in the same manner as in Example 1, except that the green blanks were stacked in the same stretching direction as in Example 1.

[0055] <Experimental Example 1>

[0056] Figure 4 Images are taken of the microstructure of Example 2. The surface of the anode support layer of Example 2 was observed using a scanning electron microscope (SEM) at various magnifications. It was confirmed that the anode support layer green body retained its porosity even after sintering.

[0057] Table 2 shows the shrinkage rates of Comparative Examples 1 to 5 and Comparative Examples 1 to 5. The longitudinal and transverse directions of the green blank's stretching direction are represented as the X-axis and Y-axis, respectively. It was confirmed that the XY difference for Examples 1 to 5 was within 0.15 mm, and the XY difference ratio relative to the size of the green blank was within 0.75%. The XY difference for Comparative Examples 1 to 5 was as high as 0.6 mm. This confirms that uniform shrinkage occurs during the cross-laminated green blank manufacturing process and sintering.

[0058] Table 2

[0059]

[0060] Figure 5 Table 3 shows the results of the three-point bending strength test for Example 2 and Comparative Example 2. Ten specimens were prepared and tested 10 times using a universal testing machine. The average tensile strength of Example 2 was approximately 137.5 MPa, and the average tensile strength of Comparative Example 2 was approximately 115.4 MPa.

[0061] Table 3

[0062]

[0063] Although the present invention has been described above with reference to preferred embodiments, it will be understood by those skilled in the art that various modifications and alterations can be made to the present invention without departing from the spirit and scope of the invention as set forth in the following claims.

Claims

1. A method for manufacturing an anode for a fuel cell, characterized in that, include: Multiple first green body manufacturing steps are used to form a first slurry containing YSZ, nickel and a pore-forming agent to produce multiple first green bodies stretched in one direction; The second green blank manufacturing step involves shaping a second slurry containing YSZ and nickel to produce a second green blank stretched in one direction. The first intermediate laminate manufacturing step involves alternately stacking the plurality of first green blanks in a cross-stretching direction manner, and then, based on this, stacking the second green blanks in a stretching direction that intersects with the stretching direction of the top first green blank to manufacture the first intermediate laminate; and The pressure sintering step involves pressure sintering the first intermediate laminate.

2. A method for manufacturing an anode for a fuel cell, characterized in that, include: Multiple first green body manufacturing steps are used to form a first slurry containing YSZ, nickel and a pore-forming agent to produce multiple first green bodies stretched in one direction. The alternating layering step involves alternating layers of the plurality of first green blanks in a cross-stretching manner; The second intermediate laminate manufacturing step involves coating a second slurry containing YSZ and nickel onto the first green blank in the laminate to manufacture the second intermediate laminate; and The pressure sintering step involves pressure sintering the second intermediate laminate.

3. The method for manufacturing an anode for a fuel cell according to claim 1 or 2, characterized in that, The weight ratio of NiO to YSZ in the first slurry is 1.5 to 2:

1. The weight ratio of NiO to YSZ in the second slurry is 1 to 1.5:

1.

4. The method for manufacturing an anode for a fuel cell according to claim 3, characterized in that, The first slurry contains 15% to 25% by volume of the pore-forming agent.

5. The method for manufacturing an anode for a fuel cell according to claim 4, characterized in that, The pore-forming agent comprises one selected from the group consisting of polymethyl methacrylate, activated carbon, carbon black, graphite, and starch.

6. The method for manufacturing an anode for a fuel cell according to claim 1, characterized in that, The thickness of the first green compact is 220 μm to 240 μm. The thickness of the second green blank is 10 μm to 14 μm.

7. The method for manufacturing an anode for a fuel cell according to claim 1 or 2, characterized in that, The sintering is carried out in an air atmosphere at 1300°C to 1500°C.

8. The method for manufacturing an anode for a fuel cell according to claim 1 or 2, characterized in that, The difference between the longitudinal average length and the transverse average length in the tensile direction after sintering of the first intermediate laminate or the second intermediate laminate is less than 0.75% of the length of the first intermediate laminate or the second intermediate laminate.

9. A laminated structure for a fuel cell anode, characterized in that, include: A fuel electrode support laminate is formed by alternately stacking multiple first green blanks in a cross-stretching manner, wherein the multiple first green blanks are manufactured using a first slurry comprising YSZ, nickel, and a pore-forming agent, and stretched in one direction; and The second green blank is manufactured by stretching in one direction using a second slurry containing YSZ and nickel, and is stacked on the top green blank in such a way that the stretching direction intersects with the stretching direction of the top green blank.

10. The laminated structure for a fuel cell anode according to claim 9, characterized in that, The weight ratio of NiO to YSZ in the first slurry is 1.5 to 2:

1. The weight ratio of NiO to YSZ in the second slurry is 1 to 1.5:

1.

11. The laminated structure for a fuel cell anode according to claim 10, characterized in that, The first slurry contains 15% to 25% by volume of the pore-forming agent.

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