A method for manufacturing a solid oxide fuel cell

Abstract

The application 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: an anode support body with hierarchical microstructure and vertical pores is prepared by adopting a freeze flow casting forming technology; an anode functional layer with a nano composite structure is prepared on the surface of the anode support body by using reactive magnetron sputtering; a micrometer-scale electrolyte and a barrier layer are prepared on the surface of the anode functional layer by using reactive magnetron sputtering; and a cathode layer is prepared on the surface of the barrier layer by using silk screen printing and low-temperature laminated co-firing. According to the method, the anode support body prepared by freeze flow casting forming has hierarchical microstructure and vertical pores, the gas diffusion resistance is reduced, and the cell concentration polarization is reduced; the reactive magnetron sputtering technology is used to refine the anode functional layer grains, reduce the activation polarization of the cell, make the electrolyte thinner, reduce the ohmic resistance, and thus 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 in particular to a method for preparing a solid oxide fuel cell. Background Art

[0002] Solid oxide fuel cells (SOFCs) are electrochemical power generation devices composed of a multilayered structure (typically, an anode support, an anode functional layer, an electrolyte layer, and a cathode layer). They offer advantages such as high conversion efficiency, fuel flexibility, and low emissions, making them a highly promising green and efficient power generation technology. However, performance and durability are key challenges for the successful commercialization of SOFC products. The existing preparation technology has the following main defects: the anode support is the basis of the gas channel of SOFC, and the anode support prepared by the traditional tape-casting process has a low porosity and the pores are tortuous, 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 place for SOFC reaction, and the anode functional layer prepared by the traditional tape-casting process or screen printing combined with high-temperature stacking co-firing process (screen printing anode functional layer and electrolyte layer, high-temperature stacking co-firing) has a coarse particle size, resulting in too low three-phase line 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 used to conduct ions. The electrolyte film prepared by tape-casting or screen printing is thicker, resulting in too high ohmic internal resistance. In order to reduce the internal resistance, the battery must not be operated at a higher temperature, but the high operating temperature accelerates the creep of the battery stack and reduces the durability of the battery.

[0003] Based on the above analysis, there is an urgent need for a preparation method for 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 solutions of the present invention are as follows:

[0006] The present invention provides a method for preparing a solid oxide fuel cell, the method comprising:

[0007] Using freeze-casting technology, an anode support with hierarchical microstructure and vertical pores was prepared;

[0008] On the surface of the anode support, an anode functional layer having a nanocomposite structure is prepared by reactive magnetron sputtering;

[0009] On the surface of the anode functional layer, a micrometer-scale electrolyte and a barrier layer are prepared by reactive magnetron sputtering;

[0010] On the surface of the barrier layer, a cathode layer is prepared by screen printing and low-temperature lamination co-firing.

[0011] Exemplarily, a freeze-casting method is used to prepare an anode support having a hierarchical microstructure and vertical pores, comprising:

[0012] The wet film of the anode support was prepared by water-based tape casting, and then the anode support with a hierarchical microstructure and vertical pores was prepared by directional freezing, vacuum drying and debinding pre-sintering.

[0013] Exemplarily, the anode support wet film is prepared by water-based tape casting, comprising:

[0014] preparing a water-based casting slurry, and casting the water-based casting slurry into an anode support wet film;

[0015] The aqueous tape-casting slurry adopts NiO and 3YSZ powders mixed in a specific proportion as aggregate, deionized water as solvent, polyacrylic acid as dispersant, polyvinyl acid as binder, polyethylene glycol and glycerol as plasticizers, and butanol as defoaming agent; the aqueous tape-casting slurry is prepared by ball milling in a planetary ball mill.

[0016] Exemplarily, preparing a water-based casting slurry comprises:

[0017] Using the aggregate and the solvent, an initial slurry having a solid content of 50-60 wt% is prepared;

[0018] Add 0.5-1.5 wt% of the above dispersant to the above initial slurry, adjust the pH to 12-14 with concentrated ammonia water, and mill using a planetary ball mill for 12-24 hours;

[0019] 3-6 wt % of the binder, 2-4 wt % of the plasticizer, and 0.5-1.2 wt % of the defoamer were added, and the mixture was ball-milled for at least 24 h using a planetary ball mill, followed by vacuum stirring to remove bubbles, thereby obtaining a water-based casting slurry.

[0020] For example, the thickness of the anode support wet film prepared by water-based tape casting is 800-1000 microns, and the anode support wet film is attached to a PET carrier film; the directional freezing and vacuum drying processes include:

[0021] Transfer the wet anode support film and the PET carrier film to a freezing platform at a temperature of -40 to -20°C and freeze for at least 20 minutes;

[0022] The freeze-formed anode support thick film is transferred to a freeze dryer for drying.

[0023] Exemplarily, the debinding and pre-burning process includes:

[0024] For the thick film of the anode support obtained by directional freezing and vacuum drying, the temperature was raised to 500°C at a rate of 0.2~0.5°C / min and kept warm for 1 hour, then raised to 1450°C at a rate of 2~5°C / min and kept warm for 3~5 hours, and then cooled to 200°C at a rate of 2~5°C / min and naturally cooled to room temperature to obtain a NiO-3YSZ anode support with hierarchical microstructure distribution and vertical pores.

[0025] Exemplarily, the anode functional layer having a nanocomposite structure is prepared by reactive magnetron sputtering, comprising:

[0026] The surface of the anode support that contacts the freezing platform during the freeze-casting process is used as a sputtering substrate. Reactive magnetron sputtering technology is used to alternately sputter Ni thin films and 8YSZ thin films, with a total of 50 to 100 film layers.

[0027] Alternatively, the surface of the anode support in contact with the freezing platform during the freeze-casting process is used as a sputtering substrate, and reactive magnetron sputtering technology is used to alternately sputter Ni thin films and GDC thin films, with a total of 50 to 100 film layers.

[0028] Exemplarily, reactive magnetron sputtering is used to prepare electrolyte and barrier layer films having a micron scale, including:

[0029] On the surface of the anode functional layer, an 8YSZ electrolyte film and a GDC barrier layer film are successively deposited by reactive magnetron sputtering, with thicknesses of 0.5-1.0 μm.

[0030] The 8YSZ electrolyte film and the GDC barrier layer film are formed by low temperature co-sintering and crystallization in air atmosphere.

[0031] Exemplarily, the cathode layer is prepared by screen printing and stacking and co-firing, comprising:

[0032] LSCF cathode layer was prepared by screen printing on the surface of the barrier layer;

[0033] The prepared solid oxide fuel cell is placed as a whole in a binder removal and sintering integrated furnace, heated to 500°C at a heating rate of 0.2~0.5°C / min and kept warm for at least 2 hours, then heated to 800~900°C at a rate of 2~5°C / min and kept warm for at least 2 hours, then cooled to 200°C at a rate of 2~5°C / min and naturally cooled to room temperature to complete sintering and obtain a finished battery product.

[0034] The above technical solution has the following advantages or beneficial effects:

[0035] This invention proposes a method for fabricating a high-performance solid oxide fuel cell. Using freeze-casting technology, the resulting anode support has a hierarchical microstructure and vertical pores, reducing gas diffusion resistance and cell concentration polarization. Reactive magnetron sputtering technology refines the grains of the anode functional layer, resulting in a higher density of three-phase lines and reduced activation polarization. Reactive magnetron sputtering also thins the electrolyte, reducing ohmic internal resistance, thereby comprehensively improving the electrochemical performance of the solid oxide fuel cell. Furthermore, because the multilayer structure is produced using low-temperature co-firing, the battery exhibits lower operating stress and thermal stress during operation, which helps improve the mechanical reliability of the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 A schematic flow chart of a method for preparing a solid oxide fuel cell provided in an embodiment of the present invention;

[0037] Figure 2 A schematic diagram of a preparation process of an anode support provided by an embodiment of the present invention;

[0038] Figure 3 This is a SEM cross-sectional view of the anode support prepared in an embodiment of the present invention;

[0039] Figure 4 The SEM cross-section and EDS element distribution diagram of the nanostructured NiO-GDC anode functional layer prepared in an embodiment of the present invention;

[0040] Figure 5 This is an SEM cross-sectional view of the LSCF cathode layer, 8YSZ electrolyte, and GDC barrier layer film prepared in an embodiment of the present invention;

[0041] Figure 6 A schematic flow chart of another method for preparing a solid oxide fuel cell provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0042] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0043] To address the issues identified in the background art, the present invention provides a method for preparing a solid oxide fuel cell. This method utilizes freeze casting, magnetron sputtering, and low-temperature co-firing to produce the solid oxide fuel cell. This method comprehensively improves the electrochemical performance of the solid oxide fuel cell. It also reduces the production temperature, thereby reducing residual stress and operating thermal stress in the battery product, and improving the mechanical reliability of the battery.

[0044] Figure 1 A flow chart of a method for preparing a solid oxide fuel cell according to 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 a different order than that shown here. Figure 1 As shown, the process includes the following steps:

[0045] S101, using freeze tape casting technology to prepare an anode support with a hierarchical microstructure and vertical pores;

[0046] S102, preparing an anode functional layer having a nanocomposite structure on the surface of the anode support by reactive magnetron sputtering;

[0047] S103, preparing a micron-scale electrolyte and barrier layer on the surface of the anode functional layer by reactive magnetron sputtering;

[0048] S104, preparing a cathode layer on the surface of the barrier layer by screen printing and low-temperature lamination co-firing.

[0049] 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.

[0050] The following is a detailed description of each of the above steps.

[0051] S101 is the step of preparing the anode support. The freeze-casting method used is a preparation process that combines water-based tape casting and directional freezing technology. Water-based tape casting is an environmentally friendly molding process that uses water as a solvent and avoids the toxicity of organic solvents. In one embodiment, S101 may specifically include: preparing an anode support wet film using water-based tape casting, and then, based on the anode support wet film, preparing an anode support having a hierarchical microstructure and vertical pores through directional freezing, vacuum drying, and binder removal pre-sintering.

[0052] Exemplarily, the aqueous tape casting includes: preparing an aqueous tape casting slurry, and tape casting the aqueous tape casting slurry into an anode support wet film. Specifically, the aqueous tape casting slurry uses NiO and 3YSZ (3 mol% yttria-stabilized zirconia, with high ionic conductivity) powder mixed in a certain proportion (for example, a weight ratio of 6:4) as aggregate, uses deionized water as solvent, uses polyacrylic acid, polyvinyl acid, polyethylene glycol and glycerol as dispersant, binder and plasticizer respectively, and uses butanol as defoaming agent, and the pre-casting slurry is prepared by a planetary ball mill. The planetary ball mill is a grinding equipment that can realize nanoscale refinement and uniform mixing of powder through the combined motion of revolution and rotation to produce high-energy collision of grinding balls. More specifically, the preparation process of the aqueous tape casting slurry includes: preparing an initial slurry with a solid content of 50-60wt% by using aggregate and solvent; adding 0.5-1.5wt% of dispersant, adjusting the pH to 12-14 with concentrated ammonia water, and ball milling for 12-24h by using a planetary ball mill; then adding 3-6wt% of binder, 2-4wt% of plasticizer and 0.5-1.2wt% of defoaming agent, and ball milling for more than 24h by using a planetary ball mill, and then vacuum stirring to remove bubbles to obtain the aqueous tape casting slurry. In one example, when vacuum stirring to remove bubbles, the vacuum pressure is 95kPa, the stirring speed is 100rpm, and the bubble removal time is about 0.5-1.0h. It should be noted that the weight percentage of the reagents used will vary within the given range according to the particle size (specific surface area) of the powder used; different ball milling times mainly affect the final size of the powder particle size, and the smaller the particle size, the better the battery performance.

[0053] Exemplarily, the thickness of the anode support wet film prepared by using the aqueous tape casting is 800-1000 microns, and the anode support wet film is attached to a PET carrier film (polyethylene terephthalate film, with high dimensional stability and low temperature resistance).

[0054] On this basis, exemplarily, the directional freezing and vacuum drying process can include: transferring the anode support wet film with the PET carrier film to a freezing platform with a temperature of-40--20℃, and freezing for at least 20min; and transferring the frozen anode support thick film into a freeze dryer for vacuum drying. Specifically, in the directional freezing stage, the freezing platform can be cooled by semiconductor refrigeration and circulating cooling water, or can be cooled by a liquid nitrogen cooling device; in the vacuum drying stage, the pressure of the freeze dryer can be set to 3-5Pa, the temperature can be controlled at-40℃, and the drying time can be at least 36h. This process can form through vertical pores through low-temperature freezing crystallization and ice crystal sublimation, and the pores near the freezing platform side are fine, the pores away from the platform side become larger and larger, i.e. a hierarchical microstructure distribution is formed.

[0055] For example, the debinding pre-sintering process mainly includes: heating the thick anode support film obtained through directional freezing and vacuum drying to 500°C at a rate of 0.2-0.5°C / min and holding it for at least 1 hour to completely decompose organic additives (such as binders and plasticizers) and achieve debinding; then heating it to 1450°C at a rate of 2-5°C / min and holding it for 3-5 hours; then cooling it to 200°C at a rate of 2-5°C / min and naturally cooling it to room temperature to complete sintering. This results in a NiO-3YSZ anode support with certain mechanical strength, hierarchical microstructure distribution, and vertical pores.

[0056] To facilitate understanding of the anode support preparation process provided by the present invention, it is described below with reference to specific examples. Figure 2 A schematic diagram of a preparation process of an anode support provided in an embodiment of the present invention is shown in FIG. Figure 2 As shown, the process includes the following steps:

[0057] S1011, preparing NiO-3YSZ slurry and degassing under vacuum conditions.

[0058] Exemplarily, this step specifically includes: dissolving NiO powder and 3YSZ powder in deionized water in a 6:4 weight ratio, maintaining a solid content of 55wt%, adding 1wt% of polyacrylic acid as a dispersant, and adding 0.5wt% of concentrated ammonia to adjust the pH to between 12 and 14, and placing it in the ball mill of a planetary ball mill for ball milling for 12 to 24 hours. 5wt% of polyvinyl acid is then added as a binder, 1.25wt% of polyethylene glycol and 1.25wt% of glycerol as a plasticizer, and 1wt% of butanol as a defoamer, and then ball milling for 24 hours. The ball-milled slurry is placed in a vacuum agitator. The vacuum pressure is set to 95kPa, and the slurry is stirred at a speed of 100rpm for a defoaming time of about 0.5-1.0h. Until the vacuum agitator stops rotating, no bubbles are generated on the slurry surface, and the prepared NiO-3YSZ slurry is taken out.

[0059] S1012, freezing platform preparation.

[0060] Use semiconductor electric refrigeration equipment with circulating water cooling system as the freezing platform, set the freezing temperature to -20 to -40℃, and wait for the set temperature to stabilize before it is ready.

[0061] S1013, water-based tape casting.

[0062] The PET film tape is used as a substrate to flow cast the defoamed NiO-3YSZ slurry prepared in step S1011, and the flow casting speed is preferably 5-10 mm / s. Exemplarily, the PET film tape is fixed on a thin copper plate (i.e., a supporting copper plate) in advance to facilitate stable transfer of the wet film in flow casting. The wet film thickness is adjusted to be 800-1200 microns by adjusting the gap width between the doctor blade and the substrate.

[0063] S1014, freeze forming.

[0064] Exemplarily, the NiO-3YSZ wet film in flow casting in S1013 is transferred together with the PET film tape and the supporting copper plate to a pre-set temperature freeze platform to be directionally frozen, and the frozen state is maintained for 20 min to form ice crystals in the wet film.

[0065] S1015, vacuum drying and sintering to obtain an anode support with obvious pore orientation.

[0066] Exemplarily, this step specifically includes: after the wet film is completely frozen to form ice crystals, the freeze-formed NiO-3YSZ thick film (or NiO-3YSZ sample) is placed together with the PET film tape and the copper plate into a freeze dryer for freeze drying. The pressure of the freeze dryer is set to be 3-5 Pa, the temperature is controlled at -40℃, and the drying is performed 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 into a degassing sintering furnace, heated to 500℃ at a rate of 0.2-0.5℃ / min and kept for 1 h for degassing, then heated to 1450℃ at a rate of 2-5℃ / min and kept for 3-5 h, and then cooled to 200℃ at a rate of 2-5℃ / min and naturally cooled to room temperature, to complete the sintering of the anode support.

[0067] Figure 3 SEM (Scanning Electron Microscopy) cross-sectional view of the anode support prepared in the embodiment of the present application. Among them, Figure 3 (a) is the overall cross-sectional SEM morphology of the anode support, (b) is the local cross-sectional SEM morphology of the anode support, and (c) is the local longitudinal cross-sectional SEM morphology of the anode support (perpendicular cross-sectional view of the horizontal cross-sectional direction).

[0068] So far, the preparation process of the anode support body is completed. The application discloses a process for preparing an anode support body through a freeze-casting process, and specifically comprises the following steps of slurry preparation, ball milling, defoaming, directional freezing, drying and sintering, etc. Through the above process, the anode support body has a hierarchical microstructure and vertical pores, reduces the gas diffusion resistance, and reduces the concentration polarization of the battery. The anode support body with obvious pores can increase the gas transport capacity of the solid oxide fuel cell, and the device and technical scheme disclosed by the application can be widely applied to the manufacturing of the anode support body.

[0069] Further, based on the anode support body, the anode functional layer, the electrolyte and the barrier layer are sputtered and deposited through steps S102-S103.

[0070] S102 is a preparation step of the anode functional layer. In one embodiment, S102 specifically can include: using a reactive magnetron sputtering technology (generating a composite thin film by exciting a metal target and a reaction gas through plasma), taking the side of the anode support body in contact with the freezing platform in the freeze-casting process, i.e., the surface with the vertical pore outlet, as a sputtering substrate, alternately sputtering a Ni thin film and an 8YSZ (8% yttria stabilized zirconia) or GDC (gadolinium-doped ceria) thin film, and forming a composite multilayer thin film structure of the anode functional layer. The thickness of the Ni thin film is about 10-20 nm, the thickness of the 8YSZ and GDC thin film is about 10-20 nm, and the total number of layers is 50-100. Exemplarily, before starting sputtering, the sputtering substrate (i.e., the sintered anode support body) can be subjected to plasma cleaning to remove surface contaminants and activate the crystal lattice.

[0071] Figure 4 The SEM cross-section and EDS (Energy Dispersive X-ray Spectroscopy) element distribution map of the nanostructured NiO-GDC anode functional layer prepared in the embodiment of the application. Among them, Figure 4 The (a) group of figures in the (a) group of figures is a sample after direct sputtering, which shows clear nano-alternating layers; Figure 4 The (b) group of figures in the (b) group of figures is a sample after 1000℃ low-temperature sintering treatment, and the anode functional layer forms a three-dimensional nano-interpenetrating network.

[0072] Through step S102, the anode functional layer with a nano-composite structure is obtained. The electrolyte and the barrier layer are further prepared on the surface of the anode functional layer.

[0073] S103 is a preparation step of the electrolyte and the barrier layer, and in one embodiment, S103 specifically can include:

[0074] An 8YSZ electrolyte film and a GDC barrier layer are deposited sequentially on the surface of the anode functional layer using reactive magnetron sputtering, each with a thickness of approximately 0.5 to 1.0 microns. The multilayer structure (anode support - functional layer - electrolyte - barrier layer) prepared through steps S101-S103 is then crystallized at low temperature in an air atmosphere, allowing atomic diffusion and bonding at the interfaces of each layer to form a densified film. For example, the multilayer structure can be transferred to a binder removal sintering furnace for low-temperature co-sintering crystallization at 1000°C and annealing for 2 hours, forming a NiO-8YSZ nanocomposite functional layer, a dense 8YSZ electrolyte film, and a GDC barrier layer.

[0075] S104 is a step of preparing a cathode layer. In one embodiment, S104 may specifically include:

[0076] LSCF (Lanthanum Strontium Cobalt Iron Oxide, a perovskite oxide, is prepared on the surface of the barrier layer by screen printing technology (by screen patterning and depositing slurry) , the optimal stoichiometric ratio for solid oxide fuel cell cathode is x=0.4, y=0.2, that is ) cathode layer, with a dry thickness of 10-30 microns. Finally, the entire battery structure prepared so far is subjected to low-temperature co-firing. This process specifically includes placing the entire battery structure in a debinding and sintering furnace, heating it to 500°C at a rate of 0.2-0.5°C / min and holding it for at least 2 hours to fully debind. Then, heating it to 800-900°C at a rate of 2-5°C / min and holding it for at least 2 hours. Then, cooling it to 200°C at a rate of 2-5°C / min and naturally cooling it to room temperature completes sintering to produce the finished battery.

[0077] Figure 5 This is a cross-sectional SEM image of the LSCF cathode layer, 8YSZ electrolyte, and GDC barrier film prepared in this embodiment of the present invention. This morphology image shows the cross-sectional SEM morphology of the micrometer-scale dense 8YSZ electrolyte and GDC barrier film after low-temperature co-firing.

[0078] This application solution has the following advantages or beneficial effects:

[0079] This invention proposes a method for fabricating a high-performance solid oxide fuel cell. Using freeze-casting, the anode support is given a hierarchical microstructure and vertical pores, reducing gas diffusion resistance and concentration polarization. The anode functional layer is refined, resulting in a higher density of three-phase lines and reduced activation polarization. The electrolyte is thinner, reducing ohmic internal resistance, thereby comprehensively improving the electrochemical performance of the solid oxide fuel cell. Furthermore, because the multilayer structure is produced using low-temperature co-firing, the battery exhibits lower operating stress and thermal stress during operation, which improves the mechanical reliability of the battery.

[0080] To facilitate understanding of the technical solution of the present invention, the preparation method provided by the present invention is illustrated below with reference to a specific embodiment. Figure 6 A schematic flow chart of a method for preparing a solid oxide fuel cell according to another embodiment of the present invention is shown. Figure 6 As shown, the process includes:

[0081] S601, prepare NiO-3YSZ tape casting slurry.

[0082] For example, deionized water is used as the solvent, polyacrylic acid, polyvinyl acid, 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 in a planetary ball mill.

[0083] For example, when preparing a tape casting slurry, NiO powder and 3YSZ powder are dissolved in deionized water in a weight ratio of 6:4, maintaining a solid content of 50-60 wt%. 0.5-1.5 wt% of a dispersant is added, and concentrated ammonia is added to adjust the pH of the suspension to between 12 and 14. The slurry is then milled in a ball mill for 12-24 hours. Then, 3-6 wt% of a binder, 2-4 wt% of a plasticizer, and 0.5-1.2 wt% of a defoamer are added, and the mixture is milled for another 24 hours.

[0084] S602, vacuum degassing the NiO-3YSZ tape casting slurry using a vacuum stirring degassing machine.

[0085] For example, during vacuum degassing, 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 to 1.0 hours. The slurry is removed after the rotation stops and no bubbles are generated on the slurry surface.

[0086] S603, the NiO-3YSZ casting slurry after vacuum degassing is cast on the surface of the PET carrier film through a casting machine to obtain a cast wet film.

[0087] Exemplarily, in the process of casting, the gap width between the doctor blade and the PET film belt is adjusted so that the thickness of the cast wet film is 800-1200 microns. Specifically, the moving speed of the casting doctor blade can be 5-10 mm / s.

[0088] S604, the cast wet film is moved to the freezing platform together with the PET film belt for directional freezing.

[0089] When directional freezing is performed, the cast wet film grows ice dendrites along the thickness direction from the substrate.

[0090] Exemplarily, the freezing platform uses a metal platform based on semiconductor refrigeration technology (optionally equipped with a circulating cooling system or liquid nitrogen to achieve lower freezing temperature).

[0091] Exemplarily, the freezing temperature is set to -40 to -20°C, and the freezing time is more than 20 min.

[0092] S605, the fully frozen thick film of the anode support body and the PET carrier film are put into a freeze dryer for vacuum drying to obtain a NiO-3YSZ sample after drying and dehydration.

[0093] Exemplarily, the pressure range of the freeze dryer is set to 3-5 Pa, the temperature is controlled at -40°C, and the sample can be easily peeled off from the PET after drying for at least 36 h.

[0094] S606, the NiO-3YSZ sample is peeled off from the PET carrier film, cut according to the design size of the battery, and the cut NiO-3YSZ sample is degassed and sintered at high temperature to prepare an anode support body with hierarchical microstructure and vertical pores.

[0095] Exemplarily, the degassing process uses a special degassing sintering furnace, and the temperature is raised to 500°C at a rate of 0.2-0.5°C / min and held for 2 h.

[0096] Exemplarily, after degassing, the temperature is raised to 1450°C at a rate of 2-5°C / min and held for 3-5 h, then reduced to 200°C at a rate of 2-5°C / min, and then naturally cooled to room temperature.

[0097] S607, Ni thin film and 8YSZ thin film are alternately deposited on the above-mentioned anode support body by reactive magnetron sputtering.

[0098] Exemplarily, the surface of the anode support body directly contacted by the freezing platform during the freezing process is selected as the deposition surface.

[0099] Exemplarily, the thickness of the Ni thin film is 10-20 nm, and the thickness of the 8YSZ thin film is 10-20 nm.

[0100] Exemplarily, the number of layers of the Ni and 8YSZ thin film is 50-100.

[0101] S608, continue to deposit 8YSZ thin film layers and GDC thin film layers on the surface of the prepared anode functional layer as electrolyte and barrier layer respectively.

[0102] Exemplarily, the target material for sputtering 8YSZ is Y15.39Zr84.51 alloy, and the atmosphere is Ar / O2; the target material for sputtering GDC is Gd21.8Ce78.1 alloy, and the atmosphere is Ar / O2.

[0103] Exemplarily, the thickness of the 8YSZ thin film and the GDC thin film is between 0.5-1.0 microns.

[0104] S609, anneal and crystallize the multilayer structure prepared by the above steps in an air atmosphere at 1000℃ to obtain a half-cell multilayer structure.

[0105] Exemplarily, the annealing holding time is 2h.

[0106] S610, prepare an LSCF cathode layer on the surface of the half-cell multilayer structure using a LSCF ink by screen printing, dry, and then sinter and shape at 800-900℃.

[0107] Exemplarily, the sintering conditions are as follows: heat to 500℃ at a rate of 0.2-0.5℃ / min, hold for 1-2h, then heat to 800-900℃ at a rate of 2-5℃ / min and hold for 1-2h, finally cool to 200℃ at a rate of 2-5℃ / min and naturally cool to room temperature.

[0108] Thus, the description of the process shown in Figure 6 is completed.

[0109] Although the present application 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 make equivalent replacements to some of the technical features, and any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A method for preparing a solid oxide fuel cell, characterized in that: include: Using freeze-casting technology, an anode support with hierarchical microstructure and vertical pores was prepared; On the surface of the anode support, an anode functional layer having a nanocomposite structure is prepared by reactive magnetron sputtering; On the surface of the anode functional layer, a micrometer-scale electrolyte and a barrier layer are prepared by reactive magnetron sputtering; On the surface of the barrier layer, a cathode layer is prepared by screen printing and low-temperature lamination co-firing; The method of preparing the cathode layer by screen printing and low-temperature stacking and co-firing comprises: Prepare an LSCF cathode layer on the surface of the barrier layer by screen printing; The prepared solid oxide fuel cell is placed as a whole in a binder removal and sintering integrated furnace, heated to 500°C at a heating rate of 0.2~0.5°C / min and kept warm for at least 2 hours, then heated to 800~900°C at a rate of 2~5°C / min and kept warm for at least 2 hours, then cooled to 200°C at a rate of 2~5°C / min and naturally cooled to room temperature to complete sintering and obtain a finished battery product.

2. The method according to claim 1, characterized in that The method adopts the freeze casting technology to prepare the anode support having a hierarchical microstructure and vertical pores, comprising: The wet film of the anode support was prepared by water-based tape casting, and then the anode support with a hierarchical microstructure and vertical pores was prepared by directional freezing, vacuum drying and debinding pre-sintering.

3. The method according to claim 2, characterized in that The method of preparing the anode support wet film by water-based tape casting comprises: preparing a water-based casting slurry, and casting the water-based casting slurry into an anode support wet film; The aqueous tape-casting slurry uses NiO and 3YSZ powders mixed in a specific proportion as aggregate, deionized water as solvent, polyacrylic acid as dispersant, polyvinyl acid as binder, polyethylene glycol and glycerol as plasticizers, and butanol as defoaming agent; the aqueous tape-casting slurry is prepared by ball milling in a planetary ball mill.

4. The method according to claim 3, characterized in that The method for preparing the water-based casting slurry comprises: Using the aggregate and the solvent to prepare an initial slurry with a solid content of 50-60 wt%; Add 0.5-1.5 wt% of the dispersant to the initial slurry, adjust the pH to 12-14 with concentrated ammonia water, and mill using a planetary ball mill for 12-24 hours; 3-6 wt % of the binder, 2-4 wt % of the plasticizer and 0.5-1.2 wt % of the defoamer were added, and the mixture was ball-milled for at least 24 hours using a planetary ball mill, and then vacuum stirred to remove bubbles to obtain a water-based casting slurry.

5. The method according to claim 2, characterized in that The thickness of the anode support wet film prepared by water-based tape casting is 800-1000 microns, and the anode support wet film is attached to the PET carrier film; The directional freezing and vacuum drying process includes: Transferring the wet anode support film along with the PET carrier film to a freezing platform at a temperature of -40 to -20°C for at least 20 minutes; The freeze-formed anode support thick film is transferred to a freeze dryer for vacuum drying.

6. The method according to claim 2, characterized in that The debinding pre-burning comprises: For the thick film of the anode support obtained by directional freezing and vacuum drying, the temperature was raised to 500°C at a rate of 0.2~0.5°C / min and kept warm for at least 1 hour, then raised to 1450°C at a rate of 2~5°C / min and kept warm for 3~5 hours, and then cooled to 200°C at a rate of 2~5°C / min and naturally cooled to room temperature to obtain a NiO-3YSZ anode support with hierarchical microstructure distribution and vertical pores.

7. The method according to claim 1, characterized in that The method of preparing the anode functional layer having a nanocomposite structure by reactive magnetron sputtering comprises: The surface of the anode support that contacts the freezing platform during the freeze-casting process is used as a sputtering substrate, and reactive magnetron sputtering technology is used to alternately sputter Ni thin films and 8YSZ thin films, with a total of 50 to 100 film layers; Alternatively, the surface of the anode support in contact with the freezing platform during the freeze-casting process is used as a sputtering substrate, and reactive magnetron sputtering technology is used to alternately sputter Ni thin films and GDC thin films, with a total of 50 to 100 film layers.

8. The method according to claim 1, characterized in that The method of preparing micron-scale electrolyte and barrier layer films by reactive magnetron sputtering comprises: On the surface of the anode functional layer, an 8YSZ electrolyte film and a GDC barrier layer film are successively sputtered and deposited by reactive magnetron sputtering, each with a thickness of 0.5 to 1.0 microns; The 8YSZ electrolyte film and the GDC barrier layer film are formed by low temperature co-sintering and crystallization in air atmosphere.

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