Preparation method of solid oxide fuel cell

Abstract

The invention relates to the technical field of fuel cells, and discloses a preparation method of a solid oxide fuel cell. The method comprises the following steps: preparing an anode support body with a hierarchical microstructure and vertical pores by adopting a freezing tape casting technology; preparing an anode functional layer with a nano composite structure on the surface of the anode support body by utilizing reactive magnetron sputtering; preparing a micron-scale electrolyte and a barrier layer on the surface of the anode functional layer by utilizing reactive magnetron sputtering; and preparing a cathode layer on the surface of the barrier layer by utilizing silk-screen printing and low-temperature lamination co-firing. According to the method provided by the invention, the anode support body prepared by freezing tape casting has a hierarchical microstructure and vertical pores, so that the gas diffusion resistance is reduced, and the concentration polarization of the battery is reduced; through a reaction magnetron sputtering technology, grains of an anode functional layer are refined, activation polarization of the cell is reduced, an electrolyte is thinner, and ohmic internal resistance is reduced, so that the electrochemical performance of the solid oxide fuel cell is comprehensively improved.

Description

Technical Field

[0001] The present invention relates to the technical field of fuel cells, and particularly to a method for preparing a solid oxide fuel cell. Background Art

[0002] A solid oxide fuel cell (SOFC) is an electrochemical power generation device composed of multiple functional structures (typical structures such as an anode support, an anode functional layer, an electrolyte layer, and a cathode layer), which has advantages such as high conversion efficiency, fuel flexibility, and low emissions, and is a green and efficient power generation technology with great potential. For the SOFC product to be successfully commercialized, performance and durability are two key challenges. The existing preparation technologies mainly have the following defects: The anode support is the gas channel foundation of the SOFC, while the anode support prepared by the traditional tape casting process has a low porosity and tortuous pores, which is not conducive to gas transmission; The anode functional layer is arranged between the anode support and the electrolyte layer and is the main reaction site of the SOFC. However, the anode functional layer prepared by the traditional tape casting process or the screen printing combined with high-temperature laminated co-firing process (screen printing the anode functional layer and the electrolyte layer, and high-temperature laminated co-firing) has a relatively large particle size, resulting in too low triple-phase boundary density and low anode oxidation reaction efficiency; The electrolyte layer is arranged between the anode functional layer and the cathode layer and is a thin film for ion conduction. The electrolyte film prepared by the tape casting or screen printing process is relatively thick, resulting in too high ohmic internal resistance. In order to reduce the internal resistance, the battery has to operate at a higher temperature, but the high operating temperature accelerates the creep of the battery stack and reduces the durability of the battery.

[0003] In summary, there is an urgent need for a method for preparing an SOFC that can ensure higher performance and durability. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for preparing a solid oxide fuel cell, so that the prepared solid oxide fuel cell has higher performance and durability.

[0005] The technical solution of the present invention is as follows: The present invention provides a method for preparing a solid oxide fuel cell, the method comprising: Adopting a freeze-casting tape casting technology to prepare an anode support with a hierarchical microstructure and vertical pores; On the surface of the above anode support, preparing an anode functional layer with a nanocomposite structure by reactive magnetron sputtering; On the surface of the above anode functional layer, preparing a micron-scale electrolyte and a barrier layer by reactive magnetron sputtering; On the surface of the above barrier layer, preparing a cathode layer by screen printing and low-temperature laminated co-firing.

[0006] Exemplarily, the freeze-casting forming method is adopted to prepare an anode support with a hierarchical microstructure and vertical pores, including: An anode support wet film is prepared by aqueous tape casting, and then an anode support with a hierarchical microstructure and vertical pores is prepared through directional freezing, vacuum drying, and debinding pre-sintering.

[0007] Exemplarily, preparing an anode support wet film by aqueous tape casting includes: Preparing an aqueous tape-casting slurry, and casting the aqueous tape-casting slurry into an anode support wet film; Among them, the above-mentioned aqueous tape-casting slurry uses NiO and 3YSZ powders mixed in a specific ratio as the aggregate, deionized water as the solvent, polyacrylic acid as the dispersant, polyvinyl alcohol as the binder, polyethylene glycol and glycerol as the plasticizers, and butanol as the defoaming agent; the aqueous tape-casting slurry is prepared by ball milling with a planetary ball mill.

[0008] Exemplarily, preparing an aqueous tape-casting slurry includes: Using the above-mentioned aggregate and the above-mentioned solvent to configure an initial slurry with a solid content of 50-60 wt%; Adding 0.5-1.5 wt% of the above-mentioned dispersant to the above-mentioned initial slurry, adjusting the pH to 12-14 with concentrated ammonia water, and ball milling for 12-24 h with a planetary ball mill; Then adding 3-6 wt% of the above-mentioned binder, 2-4 wt% of the above-mentioned plasticizer, and 0.5-1.2 wt% of the above-mentioned defoaming agent, ball milling with a planetary ball mill for at least 24 h and then performing vacuum stirring to remove bubbles to obtain an aqueous tape-casting slurry.

[0009] Exemplarily, the thickness of the anode support wet film prepared by aqueous tape casting is 800-1000 microns, and the anode support wet film adheres to a PET carrier film; the above-mentioned directional freezing and the above-mentioned vacuum drying processes include: Transferring the above-mentioned anode support wet film together with the PET carrier film to a freezing platform at a temperature of -40 to -20 °C for freezing for at least 20 min; Transferring the freeze-formed anode support thick film to a freeze dryer for drying.

[0010] Exemplarily, the debinding pre-sintering process includes: For the anode support thick film obtained through directional freezing and vacuum drying, heating it to 500 °C at a rate of 0.2-0.5 °C / min and holding for 1 h, then heating it to 1450 °C at a rate of 2-5 °C / min and holding for 3-5 h, and then cooling it to 200 °C at a rate of 2-5 °C / min and naturally cooling to room temperature to obtain a NiO-3YSZ anode support with a hierarchical microstructure distribution and vertical pores.

[0011] Exemplarily, a reaction magnetron sputtering method is used to prepare an anode functional layer with a nano-composite structure, including: Using the surface of the above-mentioned anode support that contacts the freezing platform during the freeze-casting process as the sputtering substrate, and adopting the reaction magnetron sputtering technology, Ni films and 8YSZ films are alternately sputtered, and the total number of film layers is 50 to 100 layers; Alternatively, using the surface of the above-mentioned anode support that contacts the freezing platform during the freeze-casting process as the sputtering substrate, and adopting the reaction magnetron sputtering technology, Ni films and GDC films are alternately sputtered, and the total number of film layers is 50 to 100 layers.

[0012] Exemplarily, a reaction magnetron sputtering method is used to prepare electrolyte and barrier layer films with a micron scale, including: On the surface of the above-mentioned anode functional layer, 8YSZ electrolyte films and GDC barrier layer films are successively sputtered and deposited by reaction magnetron sputtering, and the thickness of both is 0.5 to 1.0 microns; Low-temperature co-firing crystallization is carried out in an air atmosphere to form dense 8YSZ electrolyte films and GDC barrier layer films.

[0013] Exemplarily, a screen printing and co-firing lamination method is used to prepare a cathode layer, including: An LSCF cathode layer is prepared on the surface of the above-mentioned barrier layer by screen printing; The prepared solid oxide fuel cell as a whole is placed in a debinding and sintering integrated furnace, heated to 500 °C at a heating rate of 0.2 to 0.5 °C / min and held for at least 2 h, then heated to 800 to 900 °C at a rate of 2 to 5 °C / min and held for at least 2 h, and then cooled to 200 °C at a rate of 2 to 5 °C / min and then naturally cooled to room temperature to complete sintering to obtain the battery product.

[0014] The above technical solution has the following advantages or beneficial effects: The present invention proposes a method for preparing a high-performance solid oxide fuel cell. Through the freeze-casting technology, the prepared anode support has a hierarchical microstructure and vertical pores, reducing the gas diffusion resistance and the concentration polarization of the battery; through the reaction magnetron sputtering technology, the prepared anode functional layer has refined grains and a higher density of triple-phase boundaries, reducing the activation polarization of the battery; through the reaction magnetron sputtering technology, the electrolyte is thinner, reducing the ohmic internal resistance, thereby comprehensively improving the electrochemical performance of the solid oxide fuel cell. Moreover, due to the use of low-temperature co-firing to prepare multi-layer structures, the battery has lower residual stress and thermal stress during operation, which is beneficial to improving the mechanical reliability of the battery operation. Description of the Drawings

[0015] Figure 1Schematic flow chart of a method for preparing a solid oxide fuel cell provided by an embodiment of the present invention; Figure 2 Schematic flow chart of a method for preparing an anode support provided by an embodiment of the present invention; Figure 3 SEM cross-sectional view of the anode support prepared by an embodiment of the present invention; Figure 4 SEM cross-section and EDS element distribution map of the nanostructured NiO-GDC anode functional layer prepared by an embodiment of the present invention; Figure 5 SEM cross-sectional view of the LSCF cathode layer, 8YSZ electrolyte and GDC barrier layer thin films prepared by an embodiment of the present invention; Figure 6 Schematic flow chart of another method for preparing a solid oxide fuel cell provided by an embodiment of the present invention. Detailed implementation manners

[0016] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without making creative efforts belong to the scope of protection of the present invention.

[0017] To solve the problems pointed out in the background art, the present invention provides a method for preparing a solid oxide fuel cell. This method is based on freeze-casting, magnetron sputtering and low-temperature co-firing processes to prepare a solid oxide fuel cell, comprehensively improving the electrochemical performance of the solid oxide fuel cell. At the same time, the preparation temperature is reduced, thereby reducing the residual stress and operating thermal stress of the battery product and improving the mechanical reliability of the battery.

[0018] Figure 1 Schematic flow chart of a method for preparing a solid oxide fuel cell provided by an embodiment of the present invention. It should be noted that although the logical order is shown in the flow chart, in some cases, the steps shown or described can be executed in a different order than here. As Figure 1 shown, this process includes the following steps: S101, using freeze-casting technology to prepare an anode support with a hierarchical microstructure and vertical pores; S102, on the surface of the anode support, using reactive magnetron sputtering to prepare an anode functional layer with a nanocomposite structure; S103, on the surface of the anode functional layer, using reactive magnetron sputtering to prepare micron-scale electrolyte and barrier layers; S104, preparing a cathode layer on the surface of the barrier layer by screen printing and low-temperature lamination co-firing.

[0019] Thus, a solid oxide fuel cell consisting of an anode support, an anode functional layer, an electrolyte and a barrier layer, and a cathode layer is prepared.

[0020] The above steps are described in detail below.

[0021] S101 is a step for preparing the anode support. The freeze-casting method used is a preparation process that combines water-based tape casting and directional freezing technology, wherein the water-based tape casting is an environmentally friendly molding process using water as a solvent, avoiding the toxicity of organic solvents. In one embodiment, S101 may specifically include: preparing an anode support wet film by using water-based tape casting, and then preparing an anode support having a hierarchical microstructure and vertical pores based on the anode support wet film by directional freezing, vacuum drying, and debinding pre-sintering.

[0022] Exemplarily, water-based tape casting includes: preparing a water-based tape casting slurry, and casting the water-based tape casting slurry into a wet film of an anode support. Specifically, the water-based tape casting slurry uses NiO and 3YSZ (3 mol% yttria-stabilized zirconia with high ionic conductivity) powders mixed in a specific ratio (such as a weight ratio of 6:4) as aggregates, deionized water as a solvent, and polyacrylic acid, polyvinyl acid, polyethylene glycol and glycerol as dispersants, binders and plasticizers, respectively. Butanol is used as a defoamer, and a pre-cast slurry is prepared by ball milling with a planetary ball mill. Among them, the planetary ball mill is a grinding device that produces high-energy collisions in the grinding balls through the composite motion of revolution and rotation, thereby achieving nano-scale refinement and uniform mixing of the powder. More specifically, the preparation process of the water-based tape casting slurry includes: using aggregates and solvents to prepare an initial slurry with a solid content of 50-60wt%; adding 0.5-1.5wt% dispersant, adjusting the pH (degree of acidity or alkalinity) to 12-14 with concentrated ammonia water, and using a planetary ball mill for 12-24h; then adding 3-6wt% binder, 2-4wt% plasticizer and 0.5-1.2wt% defoamer, and then using a planetary ball mill for more than 24h to vacuum stir and remove bubbles to obtain a water-based tape casting slurry. In one example, when vacuum stirring and removing bubbles, the vacuum pressure is 95kPa, the stirring speed is 100rpm (revolutions per minute), and the defoaming time is about 0.5-1.0h. It should also be noted that: depending on the particle size (specific surface area) of the powder used, the weight percentage of the reagent used will vary within the given range; different ball milling times mainly affect the final size of the powder particles. The smaller the particle size, the better the battery performance.

[0023] Exemplarily, the thickness of the wet film of the anode support prepared by aqueous tape casting is 800 to 1000 microns, and the wet film of the anode support adheres to a PET carrier film (polyethylene terephthalate film, having high dimensional stability and low temperature resistance).

[0024] On this basis, exemplarily, the directional freezing and vacuum drying process may include: transferring the wet film of the anode support together with the PET carrier film to a freezing platform at a temperature of -40 to -20 °C for freezing for at least 20 min; transferring the thick film of the frozen anode support to a freeze dryer for vacuum drying. Specifically, in the directional freezing stage, the freezing platform can be cooled by both semiconductor refrigeration and circulating cooling water, or by means of a liquid nitrogen cooling device, etc.; in the vacuum drying stage, the pressure range of the freeze dryer can be set to 3 to 5 Pa, the temperature is controlled at -40 °C, and drying is carried out for at least 36 h. This process can form through vertical pores mainly by low-temperature freezing crystallization and ice crystal sublimation. Moreover, the pores are finer on the side close to the freezing platform and become larger away from this plane, that is, a hierarchical microstructure distribution is formed.

[0025] Exemplarily, the debinding and pre-sintering process mainly includes: for the thick film of the anode support obtained by directional freezing and vacuum drying, heating it to 500 °C at a rate of 0.2 to 0.5 °C / min and holding for at least 1 h to completely decompose organic additives (such as binders, plasticizers) to achieve debinding; then heating it to 1450 °C at a rate of 2 to 5 °C / min and holding for 3 to 5 h, and then cooling it to 200 °C at a rate of 2 to 5 °C / min and then naturally cooling to room temperature to complete sintering. Thus, a NiO-3YSZ anode support with certain mechanical strength, hierarchical microstructure distribution and vertical pores is obtained.

[0026] To facilitate understanding of the anode support preparation process provided by the present invention, the following will be described in conjunction with specific embodiments. Figure 2 The schematic diagram of the preparation process of an anode support provided by an embodiment of the present invention is as Figure 2 shown, and this process includes the following steps: S1011, preparing NiO-3YSZ slurry and degassing it under vacuum conditions.

[0027] Exemplarily, this step specifically includes: dissolving NiO powder and 3YSZ powder in a weight ratio of 6:4 in deionized water, maintaining the solid content at 55 wt%, adding 1 wt% of polyacrylic acid as a dispersant, and adding 0.5 wt% of concentrated ammonia water to adjust the pH to between 12 and 14, and then putting it into a ball milling tank of a planetary ball mill for ball milling for 12 to 24 h. Then, add 5 wt% of polyvinyl alcohol as a binder, 1.25 wt% of polyethylene glycol and 1.25 wt% of glycerol as plasticizers, and 1 wt% of butanol as an antifoaming agent, and then ball mill for another 24 h. Place the ball-milled slurry in a vacuum stirrer. Set the vacuum pressure to 95 kPa, stir the slurry at a speed of 100 rpm, and the defoaming time is about 0.5 - 1.0 h. Until the vacuum stirrer stops rotating and there are no bubbles on the surface of the slurry, take out the prepared NiO-3YSZ slurry.

[0028] S1012, Prepare the freezing platform.

[0029] Use a semiconductor refrigeration device combined with a circulating water cooling system as the freezing platform, set the freezing temperature to -20 to -40 °C, and wait for the set temperature to stabilize, which means it is ready.

[0030] S1013, Water-based tape casting.

[0031] Using a PET film tape as the substrate, cast the degassed NiO-3YSZ slurry prepared in step S1011. The casting speed is preferably 5 - 10 mm / s. Exemplarily, the PET film tape is fixed on a thin copper plate (i.e., the supporting copper plate) in advance to facilitate the stable transfer of the wet film formed by tape casting. By adjusting the gap width between the doctor blade and the substrate, the thickness of the wet film is made to be 800 - 1200 microns.

[0032] S1014, Freezing forming.

[0033] Exemplarily, the NiO-3YSZ wet film formed by tape casting in S1013 together with the PET film tape and the supporting copper plate can be transferred to the pre-set temperature freezing platform for directional freezing, and keep the frozen state for 20 min until the water in the wet film freezes sufficiently to form dendrites.

[0034] S1015, Obtain an anode support with obvious pore orientation through vacuum drying and sintering.

[0035] Exemplarily, this step specifically includes: After waiting for the wet film to be completely frozen to form dendrites, the frozen NiO-3YSZ thick film (or NiO-3YSZ sample), together with the PET film strip and the copper plate, is placed in a freeze dryer for freeze drying. Set the pressure range of the freeze dryer to 3-5 Pa, control the temperature at -40 °C, and dry for at least 36 h until the NiO-3YSZ thick film can be easily peeled off from the mold. Then, the NiO-3YSZ thick film is placed in a debinding and sintering furnace, heated to 500 °C at a rate of 0.2-0.5 °C / min and held for 1 h for debinding; then heated to 1450 °C at a rate of 2-5 °C / min and held for 3-5 h, and then cooled to 200 °C at a rate of 2-5 °C / min and naturally cooled to room temperature to complete the sintering of the anode support.

[0036] Figure 3 This is the SEM (Scanning Electron Microscopy) cross-sectional view of the anode support prepared in the embodiment of the present invention. Among them, Figure 3 Figure (a) in it is the overall cross-sectional SEM morphology of the anode support, Figure (b) is the local cross-sectional SEM morphology of the anode support, and Figure (c) is the local SEM morphology of the longitudinal section of the anode support (the cross-sectional view perpendicular to the cross-sectional direction).

[0037] So far, the description of the preparation process of the anode support is completed. The present invention discloses the process of preparing the anode support by the freeze-casting process, which specifically includes steps such as slurry preparation, ball milling, degassing, directional freezing, drying and sintering. Through the above process, the anode support has a hierarchical microstructure and vertical pores, reducing the gas diffusion resistance and reducing the concentration polarization of the battery. The anode support with obvious pore orientation can increase the gas transport capacity of the solid oxide fuel cell. The device and technical solution disclosed in the present invention can be widely applied to the production of this part.

[0038] Furthermore, based on this anode support, the anode functional layer, electrolyte and barrier layer are sputter-deposited through steps S102-S103.

[0039] S102 is the preparation step of the anode functional layer. In one embodiment, S102 may specifically include: using reactive magnetron sputtering technology (generating a composite film by plasma exciting a metal target and a reactive gas), with the side of the anode support in contact with the freezing platform during the freeze-casting process, that is, the surface with vertical pore outlets, as the sputtering substrate, alternately sputtering Ni film and 8YSZ (8% yttria-stabilized zirconia) or GDC (gadolinium-doped ceria) film to form an anode functional layer in the form of a composite multi-layer film structure. Among them, the thickness of the Ni film is about 10 - 20 nm, the thickness of the 8YSZ and GDC films is about 10 - 20 nm, and the total number of layers is 50 - 100 layers. Exemplarily, before starting sputtering, the sputtering substrate (i.e., the sintered anode support) can be subjected to plasma cleaning to remove surface contaminants and activate the lattice.

[0040] Figure 4 These are the SEM cross-section and EDS (Energy Dispersive X-ray Spectroscopy) element distribution maps of the nanostructured NiO-GDC anode functional layer prepared in the embodiments of the present invention. Among them, Figure 4 the group of figures (a) in it is the specimen after direct sputtering, showing clear nano-alternating layers; Figure 4 the group of figures (b) in it is the specimen after low-temperature sintering treatment at 1000 °C, and the anode functional layer forms a three-dimensional nano-interpenetrating network.

[0041] Through step S102, an anode functional layer with a nano-composite structure is obtained. Further, an electrolyte and a barrier layer are prepared on the surface of this anode functional layer.

[0042] S103 is the preparation step of the electrolyte and the barrier layer. In one embodiment, S103 may specifically include: On the surface of the anode functional layer, 8YSZ electrolyte film and GDC barrier layer film are successively sputtered and deposited by reactive magnetron sputtering, and the thickness of both is about 0.5 - 1.0 μm. Then, the multi-layer structure (anode support - functional layer - electrolyte - barrier layer) prepared through the above steps S101 - S103 is subjected to low-temperature crystallization in an air atmosphere to make the atoms at the interfaces of each layer diffuse and bond, forming a densified film layer. Exemplarily, the multi-layer structure can be transferred to a debinding and sintering furnace for low-temperature co-sintering crystallization. The sintering temperature is 1000 °C, and the holding (annealing) time is 2 h, forming a nano-composite structure functional layer of NiO - 8YSZ, a dense 8YSZ electrolyte film, and a GDC barrier layer film.

[0043] S104 is the preparation step of the cathode layer. In one embodiment, S104 may specifically include: On the surface of the barrier layer, an LSCF (lanthanum strontium cobalt ferrite oxide, a perovskite-type oxide with the general formula , and the optimal stoichiometric ratio for its use in the cathode of a solid oxide fuel cell is x = 0.4 and y = 0.2, that is ) cathode layer is prepared using screen printing technology (depositing a slurry through screen patterning). The dry thickness of the cathode layer is 10 - 30 microns. Finally, the overall battery structure prepared so far is subjected to low-temperature co-firing. This process specifically includes: placing the overall battery structure in a debinding and sintering integrated furnace, heating it at a heating rate of 0.2 - 0.5 °C / min to 500 °C and holding for at least 2 h to fully remove the binder, then heating it at a rate of 2 - 5 °C / min to 800 - 900 °C and holding for at least 2 h, and then cooling it at a rate of 2 - 5 °C / min to 200 °C and then naturally cooling to room temperature to complete the sintering and obtain the finished battery.

[0044] Figure 5 This is the SEM cross-sectional view of the LSCF cathode layer, 8YSZ electrolyte, and GDC barrier layer thin films prepared in the embodiment of the present invention. This morphology map is of the specimen after low-temperature co-firing, showing the SEM morphology of the dense 8YSZ electrolyte and GDC barrier layer thin films at the micron scale of the cross-section.

[0045] The solution of this application has the following advantages or beneficial effects: The present invention proposes a method for preparing a high-performance solid oxide fuel cell. Through freeze-casting, the anode support has a hierarchical microstructure and vertical pores, reducing the gas diffusion resistance and the concentration polarization of the battery; making the grains of the anode functional layer finer, having a higher density of triple-phase boundaries, and reducing the activation polarization of the battery; making the electrolyte thinner, reducing the ohmic internal resistance, thereby comprehensively improving the electrochemical performance of the solid oxide fuel cell. Moreover, due to the use of low-temperature co-firing to prepare the multi-layer structure, the battery has lower residual stress and thermal stress during operation, which is beneficial to improving the mechanical reliability of the battery during operation.

[0046] To facilitate the understanding of the technical solution of the present invention, the preparation method provided by the present invention is illustrated by a specific embodiment below. Figure 6 The schematic flow diagram of a method for preparing a solid oxide fuel cell provided by another embodiment of the present invention is shown, as Figure 6 shown, and this process includes: S601, preparing the NiO-3YSZ casting slurry.

[0047] Exemplarily, deionized water is used as the solvent, and polyacrylic acid, polyvinyl alcohol, polyethylene glycol, and glycerol are used as the dispersant, binder, and plasticizer respectively, and butanol is used as the defoamer. The casting slurry is prepared by ball milling with a planetary ball mill.

[0048] Exemplarily, when preparing the casting slurry, NiO powder and 3YSZ powder are mixed at a weight ratio of 6:4, dissolved in deionized water, with the solid content maintained at 50-60 wt%, 0.5-1.5 wt% of a dispersant is added, and concentrated ammonia water is added to adjust the pH of the suspension to be between 12 and 14. Then, it is put into a ball mill jar and ball milled for 12-24 h. Next, 3-6 wt% of a binder, 2-4 wt% of a plasticizer, and 0.5-1.2 wt% of an antifoaming agent are added, and ball milling is carried out for another 24 h.

[0049] S602, Use a vacuum stirring degassing machine to perform vacuum degassing on the NiO-3YSZ casting slurry.

[0050] Exemplarily, during the vacuum degassing process, the vacuum pressure is set to 95 kPa, the slurry is mixed at a speed of 100 rpm, and the degassing time is about 0.5-1.0 h. Until after stopping rotation, no bubbles are generated on the surface of the slurry, and then the slurry is taken out.

[0051] S603, Cast the vacuum degassed NiO-3YSZ casting slurry onto the surface of a PET carrier film through a casting machine to obtain a cast wet film.

[0052] Exemplarily, during the casting process, by adjusting the gap width between the doctor blade and the PET film belt, the thickness of the cast wet film is made to be 800-1200 microns. Specifically, the moving speed of the casting doctor blade can be 5-10 mm / s.

[0053] S604, Move the above-mentioned cast wet film together with the PET film belt to a freezing platform for directional freezing.

[0054] During directional freezing, ice dendrites grow from the substrate along the thickness direction of the cast wet film.

[0055] Exemplarily, the freezing platform uses a metal table based on semiconductor refrigeration technology (optionally equipped with a circulating cooling system or liquid nitrogen to achieve a lower freezing temperature).

[0056] Exemplarily, the freezing temperature is set to -40~-20 °C, and the freezing time is more than 20 min.

[0057] S605, Put the fully frozen anode-supported thick film and the PET carrier film together into a freeze dryer for vacuum drying to obtain a NiO-3YSZ sample after complete drying and dehydration.

[0058] Exemplarily, the pressure range of the freeze dryer is set to 3-5 Pa, the temperature is controlled at -40 °C, and drying is carried out for at least 36 h, and the sample can be easily peeled off from the PET.

[0059] S606. Peel the NiO-3YSZ sample from the PET carrier film, cut it according to the battery design size, and perform debinding and high-temperature sintering on the cut NiO-3YSZ sample to prepare an anode support with a hierarchical microstructure and vertical pores.

[0060] Exemplarily, for the debinding process, use a dedicated debinding and sintering furnace to heat up to 500 °C at a rate of 0.2 - 0.5 °C / min and hold for 2 h.

[0061] Exemplarily, after debinding, heat up to 1450 °C at a rate of 2 - 5 °C / min, hold for 3 - 5 h, then cool down to 200 °C at a rate of 2 - 5 °C / min, and then naturally cool to room temperature.

[0062] S607. Alternately deposit Ni thin film and 8YSZ thin film on the above anode support by reactive magnetron sputtering.

[0063] Exemplarily, select the surface of the anode support that is in direct contact with the freezing platform during the freezing process as the deposition surface.

[0064] Exemplarily, the thickness of the Ni thin film is 10 - 20 nm, and the thickness of the 8YSZ thin film is 10 - 20 nm.

[0065] Exemplarily, the number of layers of Ni and 8YSZ thin films is 50 - 100 layers.

[0066] S608. Continuously deposit an 8YSZ thin film layer and a GDC thin film layer on the surface of the prepared anode functional layer as the electrolyte and the barrier layer respectively.

[0067] Exemplarily, for sputtering 8YSZ, use a Y15.39Zr84.51 alloy target, and the atmosphere is Ar / O2; for sputtering GDC, use a Gd21.8Ce78.1 alloy target, and the atmosphere is Ar / O2.

[0068] Exemplarily, the thicknesses of both the 8YSZ thin film and the GDC thin film are between 0.5 - 1.0 microns.

[0069] S609. Anneal and crystallize the multi-layer structure prepared through the above steps in an air atmosphere at 1000 °C to obtain a half-cell multi-layer structure.

[0070] Exemplarily, the annealing holding time is 2 h.

[0071] S610. Use screen printing of LSCF ink to prepare an LSCF cathode layer on the surface of the half-cell multi-layer structure. After drying, sinter and form it at 800 - 900 °C.

[0072] Exemplarily, the sintering conditions are as follows: heating to 500 °C at a rate of 0.2 - 0.5 °C / min, holding for 1 - 2 h, then heating to 800 - 900 °C at a rate of 2 - 5 °C / min and holding for 1 - 2 h, and finally cooling to 200 °C at a rate of 2 - 5 °C / min and then naturally cooling to room temperature.

[0073] So far, the description of the Figure 6 shown process is completed.

[0074] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for preparing a solid oxide fuel cell, characterized in that, Including: Using the freeze-casting forming technology to prepare an anode support with a hierarchical microstructure and vertical pores; On the surface of the anode support, using reactive magnetron sputtering to prepare an anode functional layer with a nano-composite structure; On the surface of the anode functional layer, using reactive magnetron sputtering to prepare a micron-scale electrolyte and barrier layer; On the surface of the barrier layer, using screen printing and low-temperature co-firing to prepare a cathode layer.

2. The method according to claim 1, wherein The step of using the freeze-casting forming technology to prepare an anode support with a hierarchical microstructure and vertical pores includes: Using aqueous tape casting to prepare a wet film of the anode support, and then preparing an anode support with a hierarchical microstructure and vertical pores through directional freezing, vacuum drying, and debinding pre-sintering.

3. The method according to claim 2, characterized in that, The step of using aqueous tape casting to prepare a wet film of the anode support includes: Preparing an aqueous tape-casting slurry and casting the aqueous tape-casting slurry into a wet film of the anode support; Wherein, the aqueous tape-casting slurry uses NiO and 3YSZ powders mixed in a specific ratio as the aggregate, deionized water as the solvent, polyacrylic acid as the dispersant, polyvinyl alcohol as the binder, polyethylene glycol and glycerol as the plasticizers, and butanol as the defoamer; the aqueous tape-casting slurry is prepared by ball milling with a planetary ball mill.

4. The method according to claim 3, wherein The step of preparing the aqueous tape-casting slurry includes: Using the aggregate and the solvent to configure an initial slurry with a solid content of 50 - 60 wt%; Adding 0.5 - 1.5 wt% of the dispersant to the initial slurry, adjusting the pH to 12 - 14 with concentrated ammonia water, and ball milling for 12 - 24 h with a planetary ball mill; Then adding 3 - 6 wt% of the binder, 2 - 4 wt% of the plasticizers, and 0.5 - 1.2 wt% of the defoamer, ball milling with a planetary ball mill for at least 24 h and then performing vacuum stirring to remove bubbles to obtain the aqueous tape-casting slurry.

5. The method according to claim 2, characterized in that, The wet film of the anode support prepared by aqueous tape casting has a thickness of 800 - 1000 microns, and the wet film of the anode support adheres to the PET carrier film; The directional freezing and the vacuum drying process include: Transferring the wet film of the anode support together with the PET carrier film to a freezing platform at a temperature of -40 to -20 °C for freezing for at least 20 min; Transferring the thick film of the frozen-formed anode support to a freeze dryer for vacuum drying.

6. The method according to claim 2, wherein The debinding pre-sintering includes: For the thick film of the anode support obtained through directional freezing and vacuum drying, heating it to 500 °C at a rate of 0.2 - 0.5 °C / min and holding for at least 1 h, then heating it to 1450 °C at a rate of 2 - 5 °C / min and holding for 3 - 5 h, and then cooling it to 200 °C at a rate of 2 - 5 °C / min and then naturally cooling to room temperature to obtain a NiO-3YSZ anode support with a hierarchical microstructure distribution and vertical pores.

7. The method according to claim 1, wherein The step of using reactive magnetron sputtering to prepare an anode functional layer with a nano-composite structure includes: Taking the surface of the anode support that contacts the freezing platform during the freeze-casting forming process as the sputtering substrate, and using reactive magnetron sputtering technology to alternately sputter Ni films and 8YSZ films, and the total number of film layers is 50 - 100 layers; Alternatively, taking the surface of the anode support that contacts the freezing platform during the freeze-casting process as the sputtering substrate, using reactive magnetron sputtering technology, Ni thin films and GDC thin films are alternately sputtered, and the total number of film layers is 50 to 100 layers.

8. The method according to claim 1, wherein The preparation of micron-scale electrolyte and barrier layer thin films by reactive magnetron sputtering includes: On the surface of the anode functional layer, an 8YSZ electrolyte thin film and a GDC barrier layer thin film are successively sputtered and deposited by reactive magnetron sputtering, and the thickness of both is 0.5 to 1.0 microns; Low-temperature co-firing and crystallization are carried out in an air atmosphere to form a dense 8YSZ electrolyte thin film and a GDC barrier layer thin film.

9. The method according to claim 1, wherein The preparation of the cathode layer by screen printing and low-temperature laminated co-firing includes: An LSCF cathode layer is prepared by screen printing on the surface of the barrier layer; The overall solid oxide fuel cell prepared is placed in a debinding and sintering integrated furnace, heated to 500 °C at a heating rate of 0.2 to 0.5 °C / min and held for at least 2 h, then heated to 800 to 900 °C at a rate of 2 to 5 °C / min and held for at least 2 h, and then cooled to 200 °C at a rate of 2 to 5 °C / min and naturally cooled to room temperature to complete sintering to obtain the battery finished product.

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