Preparation method of anode support body based on freeze casting solid oxide fuel cell

Abstract

The invention discloses a preparation method of an anode support of a solid oxide fuel cell, which is based on a freezing tape casting process, designs and prepares an applicable one-way freezing tape casting mold, and builds a simple freezing tape casting device in combination with the mold. Meanwhile, the invention further provides a complete preparation process of the NiO-3YSZ anode support with the obvious pore direction, and the preparation process comprises the specific preparation processes of slurry preparation, ball milling, defoaming, freezing and casting, drying and sintering and the like. According to the freezing casting device and the preparation process, the anode support with obvious pore direction can be prepared, the anode support is beneficial to gas transmission, the gas transportation capability of the anode support of the solid oxide fuel cell can be improved, and the performance of an SOFC product is improved.

Description

Technical Field

[0001] The invention belongs to the field of methods for preparing an anode support of a solid oxide fuel cell, and in particular relates to a method for preparing an anode support of a solid oxide fuel cell based on freeze-casting. Background Art

[0002] Anode-supported solid oxide fuel cell (SOFC) has the advantages of high conversion efficiency, fuel flexibility, low emissions and structural stability, and is a very promising green and efficient power generation technology.

[0003] One of the key challenges for SOFC products to be successfully commercialized is to improve their performance. The anode support prepared by the traditional tape-casting process has a low porosity and is evenly distributed, which is not conducive to gas transmission.

[0004] Freeze casting is a porous ceramic preparation technology that uses water solvent to control the pore direction through a highly anisotropic solidification process, including slurry preparation, directional solidification, particle redistribution, sublimation, formation of directional pores, sintering and other steps. Freeze casting technology is environmentally friendly and cost-effective, and can be used to control the pore distribution of the anode support. Summary of the invention

[0005] The object of the present invention is to provide a method for preparing an anode support having directional pores based on freeze casting technology, which can reduce the gas transport resistance of the anode support and improve the performance of SOFC products.

[0006] The present invention is achieved by a method for preparing an anode support for a freeze-cast solid oxide fuel cell, comprising the following steps:

[0007] S10. A unidirectional freeze-casting mold is prepared and the prepared mold is placed in a constant temperature box; the mold has a cavity inside, and the wall of the cavity has a certain thickness to ensure that the temperature change occurs only in the vertical direction;

[0008] S20. Preparing a pre-cast NiO-3YSZ slurry;

[0009] S30. Using a vacuum mixer, the pre-cast NiO-3YSZ slurry is vacuum degassed;

[0010] S40. The mold is removed from the thermostat, fixed on a copper plate, and the copper plate is placed on a cold plate of a thermoelectric cooler, assembled into a frozen casting device, and the temperature of the thermoelectric cooler is set;

[0011] S50. The degassed NiO-3YSZ slurry is slowly poured into the cavity of the mold for freeze casting, and ice crystals are allowed to grow;

[0012] S60. The mold and the cast NiO-3YSZ sample are placed in a freeze dryer together, and vacuum dried at a suitable temperature and pressure until the NiO-3YSZ sample can be peeled off from the mold;

[0013] S70. Peeling the NiO-3YSZ sample from the mold, and performing debinding and high-temperature sintering on the NiO-3YSZ sample, thereby obtaining an anode support having obvious pores.

[0014] Furthermore, in the step S10, the mold is printed using 3D printing equipment and ABS material.

[0015] Furthermore, the overall shape of the mold is a cylinder of φ5cm×3mm, and the size of the cavity is φ2.5cm×3mm.

[0016] Furthermore, the preparation steps of the NiO-3YSZ slurry include: dissolving NiO powder and 3YSZ powder in deionized water in a weight ratio of 6:4, maintaining the solid content at 50-60wt%, adding 0.5-1.5wt% of a dispersant, and adding concentrated ammonia water to adjust the pH, placing it in a ball mill for 12h; then adding 3-6wt% of a binder, 2-4wt% of a plasticizer; 0.5-1.2wt% of a defoamer, and then ball milling for 24h.

[0017] Furthermore, in the preparation steps of the NiO-3YSZ slurry, polyacrylic acid is used as a dispersant, polyvinyl acid is used as a binder, polyethylene glycol and glycerol are used as plasticizers, butanol is used as a defoaming agent, and a planetary ball mill is used for ball milling.

[0018] Furthermore, the vacuum degassing process in step S30 is as follows: put the NiO-3YSZ slurry into a vacuum mixer, set the vacuum pressure to 95 kPa, mix the NiO-3YSZ slurry at a speed of 100 rpm, and remove bubbles for a period of time; until the rotation stops and no bubbles are generated on the surface of the NiO-3YSZ slurry, take out the NiO-3YSZ slurry.

[0019] Furthermore, in the step S50, the temperature of freeze casting is set to -20°C, and when the height of the poured NiO-3YSZ slurry reaches 1 / 3 of the height of the mold, the pouring of the NiO-3YSZ slurry is stopped; at this time, the temperature is vertically transmitted from the bottom surface of the NiO-3YSZ slurry in the mold cavity to the upper surface of the NiO-3YSZ slurry, realizing unidirectional freeze casting, waiting for ice crystals to grow until the NiO-3YSZ slurry is completely frozen.

[0020] Furthermore, in the step S60, the freeze dryer is set at a pressure range of 3 to 5 Pa, the temperature is controlled at -40°C, and the drying is performed for at least 36 hours until the NiO-3YSZ sample can be easily peeled off from the mold.

[0021] Furthermore, in the step S70, the binder removal conditions of the NiO-3YSZ sample are as follows: placing the NiO-3YSZ sample in a muffle furnace, heating the temperature to 500° C. at a heating rate of 1° C. / min, and keeping the temperature for 1 hour.

[0022] Furthermore, in the step S70, the high temperature sintering conditions of the NiO-3YSZ sample are: heating to 1450° C. at a heating rate of 2° C. / min and keeping the temperature for 3 hours.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] The method for preparing the anode support of a solid oxide fuel cell provided by the present invention is based on a freeze casting process, and a suitable unidirectional freeze casting mold is designed and prepared, and a simple freeze casting device is built in combination with the mold. At the same time, the present invention also provides a complete preparation process of a NiO-3YSZ anode support with obvious pore direction, including specific preparation processes such as slurry preparation, ball milling, degassing, freeze casting, drying and sintering. Through the freeze casting device and preparation process of the present invention, an anode support with obvious pore direction can be prepared, and the anode support is conducive to the transmission of gas, which can improve the gas transport capacity of the anode support of the solid oxide fuel cell and improve the performance of the SOFC product. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A flow chart of a method for preparing an anode support for a freeze-cast solid oxide fuel cell provided in an embodiment of the present invention;

[0026] Figure 2 A cross-sectional view of a unidirectional freeze-casting mold and a freeze-casting device provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0028] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "front", "rear", "vertical", "horizontal", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention; the terms "first", "second", and "third" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance; in addition, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected, or indirectly connected through an intermediate medium, or it can be a connection between the two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0029] See also Figure 1 , which is a flow chart of a method for preparing an anode support for a freeze-cast solid oxide fuel cell based on an embodiment of the present invention. It should be noted that although a logical order is shown in the flow chart, in some cases, the steps shown or described may be performed in an order different from that shown here.

[0030] The method for preparing the anode support comprises the following steps:

[0031] Step S10: Prepare a unidirectional freezing casting mold, use 3D printing equipment and ABS material to prepare a cylinder (φ5cm×3mm) with a cavity (φ2.5cm×3mm), and the wall thickness of the mold is 1.25cm to ensure that temperature changes only occur in the vertical direction.

[0032] Step S20: Prepare NiO-3YSZ slurry and defoam it under vacuum conditions. The specific preparation steps are as follows: Dissolve NiO powder and 3YSZ powder in deionized water in a weight ratio of 6:4, keep the solid content at 55wt%, add 1wt% polyacrylic acid as a dispersant, and add 0.5wt% concentrated ammonia water to adjust the pH, and put it into a ball mill for 12h. Then add 5wt% polyacrylic acid as a binder, 1.25wt% polyethylene glycol and 1.25wt% polyethylene glycol as a plasticizer, plus 1wt% butanol as a defoamer, and then ball mill for 24h. Place the ball-milled slurry in a vacuum mixer. Set the vacuum pressure to 95kPa, mix the slurry at a speed of 100rpm, and defoam for about 1h until the rotation stops and no bubbles are generated on the surface of the slurry, and take out the NiO-3YSZ slurry.

[0033] Step S30: While the vacuum mixer is debubbling the slurry, assemble the freeze casting device and set the temperature. The specific steps are: fix the prepared mold at the center of the top surface of the copper plate and place it on the center of the cold plate of the thermoelectric cooler, set the temperature of the thermoelectric cooler to -20°C, and wait for the temperature to drop.

[0034] Step S40: Slowly pour the degassed NiO-3YSZ slurry into the mold for freeze casting. The specific steps are: when the temperature of the freeze casting device drops to -20°C, slowly pour the degassed NiO-3YSZ slurry into the cavity along the mold wall, and the height of the poured slurry is about 1 / 3 of the mold height. At this time, the temperature is vertically transmitted from the bottom surface of the slurry in the mold cavity to the upper surface of the slurry, realizing unidirectional freeze casting and waiting for ice crystals to grow. The cross-sectional diagram of the device for pouring slurry is shown in the figure. Figure 2 shown.

[0035] Step S50: Through the drying and sintering process, an anode support with obvious pores is obtained. The specific steps are: after waiting for the NiO-3YSZ slurry to be completely frozen, the NiO-3YSZ sample, the mold and the copper plate are placed in a freeze dryer for freeze drying. The pressure range of the freeze dryer is set to 3-5 Pa, the temperature is controlled at -40 ° C, and it is dried for at least 36 hours until the NiO-3YSZ sample can be easily peeled off from the mold. Next, the NiO-3YSZ sample is placed in a muffle furnace, heated to 500 ° C at a heating rate of 1 ° C / min and kept warm for 1 hour for debinding; then heated to 1450 ° C at a heating rate of 2 ° C / min and kept warm for 3 hours to complete sintering, and an anode support with obvious pores is obtained.

[0036] In summary, the present embodiment is based on the freeze-casting process, designs and prepares a suitable unidirectional freeze-casting mold, and builds a simple freeze-casting device in combination with the mold. At the same time, the present embodiment also provides a complete preparation process of a NiO-3YSZ anode support with obvious pores, including the specific preparation processes such as the preparation of slurry, ball milling, deaeration, freeze-casting, drying and sintering. Through the freeze-casting device and preparation process of the present embodiment, an anode support with obvious pores can be prepared, which is conducive to the transmission of gas, can improve the gas transport capacity of the anode support of the solid oxide fuel cell, and improve the performance of the SOFC product.

[0037] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing an anode support for a freeze-cast solid oxide fuel cell, characterized in that: The following steps are involved: S10. A unidirectional freeze-casting mold is prepared and the prepared mold is placed in a constant temperature box; the mold has a cavity inside, and the wall of the cavity has a certain thickness to ensure that the temperature change occurs only in the vertical direction; S20. Preparing a pre-cast NiO-3YSZ slurry; S30. Using a vacuum mixer, the pre-cast NiO-3YSZ slurry is vacuum degassed; S40. The mold is removed from the thermostat, fixed on a copper plate, and the copper plate is placed on a cold plate of a thermoelectric cooler, assembled into a frozen casting device, and the temperature of the thermoelectric cooler is set; S50. The degassed NiO-3YSZ slurry is slowly poured into the cavity of the mold for freeze casting, and ice crystals are allowed to grow; S60. The mold and the cast NiO-3YSZ sample are placed in a freeze dryer together, and vacuum dried at a suitable temperature and pressure until the NiO-3YSZ sample can be peeled off from the mold; S70. Peeling the NiO-3YSZ sample from the mold, and performing debinding and high-temperature sintering on the NiO-3YSZ sample, thereby obtaining an anode support having obvious pores.

2. The method for preparing an anode support according to claim 1, characterized in that: In the step S10, the mold is printed using 3D printing equipment and ABS material.

3. The method for preparing an anode support according to claim 2, characterized in that: The overall shape of the mold is a cylinder of φ5cm×3mm, and the size of the cavity is φ2.5cm×3mm.

4. The method for preparing an anode support according to claim 1, characterized in that: The preparation steps of the NiO-3YSZ slurry include: dissolving NiO powder and 3YSZ powder in deionized water in a weight ratio of 6:4, maintaining a solid content of 50-60wt%, adding 0.5-1.5wt% of a dispersant, adding concentrated ammonia water to adjust the pH, and placing the mixture in a ball mill for 12h; then adding 3-6wt% of a binder, 2-4wt% of a plasticizer, and 0.5-1.2wt% of a defoamer, and then ball milling for 24h.

5. The method for preparing an anode support according to claim 4, characterized in that: Polyacrylic acid is used as a dispersant, polyvinyl acid is used as a binder, polyethylene glycol and glycerol are used as plasticizers, butanol is used as a defoaming agent, and a planetary ball mill is used for ball milling.

6. The method for preparing an anode support according to claim 1, characterized in that: The vacuum degassing process in step S30 is as follows: put the NiO-3YSZ slurry into a vacuum mixer, set the vacuum pressure to 95 kPa, mix the NiO-3YSZ slurry at a speed of 100 rpm, and remove bubbles for a period of time; until the rotation stops and no bubbles are generated on the surface of the NiO-3YSZ slurry, take out the NiO-3YSZ slurry.

7. The method for preparing an anode support according to claim 1, characterized in that: In the step S50, the temperature of freeze casting is set to -20°C. When the height of the poured NiO-3YSZ slurry reaches 1 / 3 of the mold height, the pouring of NiO-3YSZ slurry is stopped. At this time, the temperature is vertically transmitted from the bottom surface of the NiO-3YSZ slurry in the mold cavity to the upper surface of the NiO-3YSZ slurry, realizing unidirectional freeze casting, waiting for ice crystals to grow until the NiO-3YSZ slurry is completely frozen.

8. The method for preparing an anode support according to claim 1, characterized in that: In the step S60, the freeze dryer is set at a pressure range of 3 to 5 Pa, the temperature is controlled at -40°C, and the drying is performed for at least 36 hours until the NiO-3YSZ sample can be easily peeled off from the mold.

9. The method for preparing an anode support according to claim 1, characterized in that: In the step S70, the binder removal conditions of the NiO-3YSZ sample are as follows: the NiO-3YSZ sample is placed in a muffle furnace, heated to 500° C. at a heating rate of 1° C. / min, and kept warm for 1 hour.

10. The method for preparing an anode support according to claim 1, characterized in that: In the step S70, the high temperature sintering conditions of the NiO-3YSZ sample are: heating to 1450°C at a rate of 2°C / min and keeping the temperature for 3 hours.

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