Solid oxide fuel cell composite support, preparation method thereof, solid oxide fuel cell and preparation method thereof

Abstract

The present invention relates to a solid oxide fuel cell, and provides a solid oxide fuel cell composite support, a preparation method thereof, a solid oxide fuel cell and a preparation method thereof, wherein the preparation method of the solid oxide fuel cell composite support comprises the following steps: S1, preparing a sacrificial layer slurry, a supporting layer slurry, and a transition layer slurry; S2, placing the sacrificial layer slurry, the supporting layer slurry, and the transition layer slurry in a casting machine in this order, with the sacrificial layer slurry placed at the bottom; after casting, the obtained green body is subjected to phase inversion curing in a water bath, and the sacrificial layer is removed to obtain a composite support. The preparation method of the composite support provided by the present invention synergistically optimizes thermal expansion matching through a phase inversion finger-shaped pore supporting layer and a gradient transition layer, combined with interface strengthening, significantly improving the bonding strength and battery electrochemical performance, and is suitable for vehicle-mounted and distributed energy systems.

Description

Technical Field

[0001] The present invention relates to a solid oxide fuel cell, and in particular to a solid oxide fuel cell composite support, a preparation method thereof, a solid oxide fuel cell and a preparation method thereof. Background Art

[0002] Solid oxide fuel cells (SOFCs) are highly efficient, environmentally friendly, and effective energy conversion devices that directly convert the chemical energy of a fuel (such as hydrogen or methane) and an oxidant (typically oxygen) into electrical energy. The basic structure of a traditional SOFC consists of an anode, cathode, electrolyte, and bipolar plates. The anode, cathode, or electrolyte supports are often made of ceramic or metal-ceramic supports (such as electrolyte supports or anode supports). These supports suffer from poor thermal shock resistance and slow startup times (requiring several hours).

[0003] Metal-supported SOFC (MS-SOFC) significantly optimizes performance and application scenarios by introducing a metal matrix. As a combined heat and power system, MS-SOFC utilizes industrial by-product gas to generate electricity, achieving an energy utilization rate of over 80%. In addition, it also has broad application prospects as an auxiliary power source for heavy-duty vehicles and ships. However, the interfacial bonding problem between the metal support and the electrolyte / electrode functional layer is like a "double-edged sword." While it provides structural stability, it also becomes a key bottleneck restricting battery performance and life. The core of this contradiction stems from the differences in the intrinsic properties of metals and ceramic materials under multi-field coupling environments such as thermal, electrical, and chemical fields. The mismatch in thermal expansion coefficients induces interfacial stress concentration, high-temperature oxidation leads to element interdiffusion, and the charge transfer barrier at the heterogeneous interface increases. These challenges directly target the engineering lifeline of MS-SOFC technology.

[0004] From the perspective of interface bonding, the co-sintering of the metal support and the electrolyte layer needs to be completed at a low temperature (usually <1100°C) to avoid metal oxidation. However, the densification of electrolytes such as YSZ usually requires a high temperature of more than 1400°C. This requires a compromise during the battery preparation process, and the support needs to be protected to avoid excessive oxidation of the metal support and ensure the sintering density of the electrolyte. In addition, the bonding between the metal and the electrolyte relies on a weak oxide bond, and the bonding strength between the two is relatively low, and they are prone to delamination under thermal shock. Therefore, in order to ensure full bonding between the metal and the ceramic, a transition layer needs to be added to increase the contact area between the two.

[0005] At the reaction sites, a large number of three-phase interfaces within 10-20 μm near the electrolyte are required to ensure battery efficiency. This requires a porous and loose structure near the electrolyte layer to achieve a large number of three-phase interfaces. However, excessive porosity makes the already weak metal-ceramic bond even more difficult to meet the requirements of battery operation, and different pore creation methods also cause different impact stresses on the electrolyte and supporting electrode.

[0006] Therefore, providing an appropriate metal support is of great significance to solving the bonding problem between metal and electrolyte in MS-SOFC. Summary of the Invention

[0007] The technical problem solved by the present invention is to provide a method for preparing a composite support for a solid oxide fuel cell. The preparation method provided in this application can achieve a close combination of the support layer and the electrolyte, ultimately ensuring the electrochemical performance of the solid oxide fuel cell.

[0008] In view of this, the present application provides a method for preparing a solid oxide fuel cell composite support, comprising the following steps:

[0009] S1. Prepare sacrificial layer slurry, support layer slurry and transition layer slurry;

[0010] S2. Place the sacrificial layer slurry, support layer slurry, and transition layer slurry in a tape casting machine in this order, with the sacrificial layer slurry placed at the bottom. After tape casting, phase inversion solidify the resulting green body in a water bath, remove the sacrificial layer, and obtain a composite support body.

[0011] The sacrificial layer slurry includes a first solvent, a first solute, a first dispersant and a first binder;

[0012] The supporting layer slurry includes a second solvent, a second solute, a second dispersant and a second binder;

[0013] The transition layer slurry includes a third solvent, a third solute, a third dispersant and a third binder;

[0014] The first solute and the second solute are independently selected from metal powders, and the third solute is selected from a mixed powder of metal powders and electrolyte ceramic powders;

[0015] The first solvent, the second solvent and the third solvent are the same;

[0016] The second binder and the third binder are the same, and the first binder and the second binder are different;

[0017] The solid content of the sacrificial layer slurry is greater than the solid content of the supporting layer slurry and greater than the solid content of the transition layer slurry.

[0018] In some specific embodiments, in the sacrificial layer slurry, the content of the first solvent is 25~35wt%, the content of the first solute is 55~70wt%, the content of the first dispersant is 0.5~5wt%, and the content of the first binder is 2~10wt%; and / or, in the supporting layer slurry, the content of the second solvent is 30~40wt%, the content of the second solute is 50~65wt%, the content of the second dispersant is 0.5~5wt%, and the content of the second binder is 2~10wt%; and / or, in the transition layer slurry, the content of the third solvent is 35~45wt%, the content of the third solute is 45~60wt%, the content of the third dispersant is 0.5~5wt%, and the content of the third binder is 2~10wt%.

[0019] In some specific embodiments, the first solvent, the second solvent, and the third solvent are selected from one or more of 1-methyl-2-pyrrolidone, ethanol, and propanol;

[0020] And / or, the metal powder is selected from one or more of 430L powder, Fe-Cr-Ni alloy powder and P434L powder, and the electrolyte ceramic powder is selected from one or more of SSZ, YSZ, SDC, GDC, LSGM and BZCY.

[0021] In some specific embodiments, the first dispersant and the second dispersant are independently selected from one or more of polyvinyl pyrrolidone, triethanolamine, polyethylene glycol, oleic acid and acetone, and the third dispersant is selected from one or more of polyvinyl pyrrolidone, acrylic resin, triethanolamine and unsaturated polycarboxylic acid;

[0022] and / or, the first binder is selected from one or more of polyethersulfone, polyvinyl butyral, polypropylene and polyvinyl alcohol;

[0023] The second binder is selected from one or both of polyvinyl butyral and polyethersulfone.

[0024] In some specific embodiments, the temperature of the water bath is 20-30° C., and the curing time is 12-36 hours;

[0025] And / or, during the casting process, the thickness of the sacrificial layer is 400-800 μm, the thickness of the support layer is 300-800 μm, and the thickness of the transition layer is 100-200 μm.

[0026] The present application also provides a composite support body prepared by the preparation method, comprising a support layer and a transition layer, wherein the support layer has a finger-like pore structure, the second solute of the transition layer has a concentration gradient distribution, and the metal powder content near the support layer end is higher than the metal powder content far from the support layer end, and the electrolyte powder content near the support layer end is lower than the electrolyte powder content far from the support layer end.

[0027] The present application also provides a solid oxide fuel cell, comprising a cathode, an electrolyte, a support and an anode, wherein the support is prepared by the preparation method described in the above scheme or the composite support described in the above scheme, and the electrolyte is in contact with the transition layer of the support.

[0028] The present application also provides a method for preparing the solid oxide fuel cell, comprising the following steps:

[0029] The electrolyte was prepared by tape casting;

[0030] Preheating and pre-pressing a support, stacking the pre-pressed support and the electrolyte, preheating, and then pressing, wherein the support is prepared by the preparation method described in the above scheme or the composite support described in the above scheme, and the electrolyte is in contact with the transition layer of the support;

[0031] The pressed half-cell is debinded and then sintered, and then a cathode and an anode are respectively prepared on both sides of the sintered half-cell to obtain a solid oxide fuel cell.

[0032] In some specific embodiments, the electrolyte slurry of the tape casting method includes ceramic powder, solvent, binder, plasticizer and dispersant; wherein the ceramic powder is selected from one or more of SSZ, YSZ, SDC, GDC, LSCM and BZCY, with a content of 45-60wt%; the solvent is selected from one or more of anhydrous ethanol, xylene, butyl acetate and butanone, with a content of 30-40wt%; the binder is selected from one or more of polyvinyl butyral and epoxy resin, with a content of 2-10wt%; the plasticizer is selected from one or more of polyethylene glycol, diester phthalate and polyethylene oxide, with a content of 2-8wt%; the dispersant is selected from one or more of triethanolamine, acrylic resin and oleic acid, with a content of 0.5-4wt%;

[0033] And / or, the support is preheated at a temperature of 60-85° C. for 5-30 min, and pre-pressed at a pressure of 5-10 MPa for 30 s-50 min;

[0034] And / or, the preheating temperature after stacking is 60-85° C., the time is 5-30 min, and the pressing pressure is 5-30 MPa, the time is 1-10 min;

[0035] And / or, the debinding temperature is 200-600°C, and the heating rate is 0.1-1°C / min;

[0036] And / or, the sintering temperature is 1300-1500° C., the time is 2-6 hours, and the sintering atmosphere is selected from 10% H2-90% Ar, 5% H2-95% Ar, 10% H2-90% N2 or 5% H2-95% N2.

[0037] In some specific embodiments, the sintering further comprises:

[0038] preparing a functional layer on the electrolyte surface of the sintered half-cell;

[0039] The preparation slurry of the functional layer includes ceramic powder, solvent and dispersant; the ceramic powder is selected from one or more of SSZ, YSZ, SDC, GDC, LSCM and BZCY, with a content of 5~20wt%, the solvent is selected from one or more of anhydrous ethanol, propanol, N-methylpyrrolidone and butanone, with a content of 70~90wt%, the dispersant is selected from one or more of polyethylene glycol, Triton X-100 and ammonium polyacrylate, with a content of 2~10wt%, and the solid content of the prepared slurry is 5~20%.

[0040] The present application provides a method for preparing a composite support body for a solid oxide fuel cell, which comprises first preparing a sacrificial layer slurry, a supporting layer slurry and a transition layer slurry, then using a multilayer phase conversion casting technique to prepare a blank body of the sacrificial layer, the supporting layer and the transition layer, and finally removing the sacrificial layer to obtain a composite support body; the preparation method provided in the present application limits the composition and solid content of the sacrificial layer slurry, the supporting layer slurry and the transition layer slurry, so that the supporting layer in the obtained composite support body has finger-shaped through macropores, and the transition layer can form a gradient transition structure with a high electrolyte content near the electrolyte end and a high metal content near the supporting layer end, thereby achieving a close combination of the electrolyte and the support body, and at the same time, the loose pore structure of the supporting layer and the transition layer ensures the three-phase interface of the battery reaction, thereby ensuring the electrochemical performance of the solid oxide fuel cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 A schematic diagram of the preparation process of a solid oxide fuel cell provided in Example 1 of the present invention;

[0042] Figure 2 Schematic diagram of the solid oxide fuel cell prepared in Example 1 and Example 2 of the present invention; Figure 2 (a) is a schematic diagram of the solid oxide fuel cell prepared in Example 1, Figure 2 (b) Schematic diagram of the solid oxide fuel cell prepared in Example 2;

[0043] Figure 3 Scanned photos of the cross section of the battery prepared in Example 1 of the present invention and scanned photos of the combination of the electrolyte and the transition layer; Figure 3 (a) is a cross-sectional photograph of the electrolyte of the solid oxide fuel cell prepared in Example 1. Figure 3 (b) is a cross-sectional photograph of the solid oxide fuel cell prepared in Example 1;

[0044] Figure 4 This is a photo of the half-cell prepared in Example 1 of the present invention;

[0045] Figure 5 This is a scanned photo of the entire cross section of the solid oxide fuel cell prepared in Example 2;

[0046] Figure 6 This is a power density curve of the solid oxide fuel cell prepared in Example 1 at various temperatures;

[0047] Figure 7 This is a scanned photo of the entire cross section of the solid oxide fuel cell prepared in Example 3;

[0048] Figure 8 This is a scanning photo of the transition layer prepared by ordinary casting in Comparative Example 2. DETAILED DESCRIPTION

[0049] In order to further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, rather than limiting the claims of the present invention.

[0050] In view of the requirement for a close bond between the metal support and the electrolyte of a solid oxide fuel cell in the prior art, the present application provides a method for preparing a composite support for a solid oxide fuel cell. The method uses a multilayer phase conversion casting method to prepare a composite support having a transition layer with a concentration gradient transition and a support layer with exposed, finger-like pores. This allows the electrolyte and the support layer to be tightly bonded, ultimately ensuring the electrochemical performance of the solid oxide fuel cell. Specifically, an embodiment of the present invention discloses a method for preparing a composite support for a solid oxide fuel cell, comprising the following steps:

[0051] S1. Prepare sacrificial layer slurry, support layer slurry and transition layer slurry;

[0052] S2. Place the sacrificial layer slurry, support layer slurry, and transition layer slurry in a tape casting machine in this order, with the sacrificial layer slurry placed at the bottom. After tape casting, phase inversion solidify the resulting green body in a water bath, remove the sacrificial layer, and obtain a composite support body.

[0053] The sacrificial layer slurry includes a first solvent, a first solute, a first dispersant and a first binder;

[0054] The supporting layer slurry includes a second solvent, a second solute, a second dispersant and a second binder;

[0055] The transition layer slurry includes a third solvent, a third solute, a third dispersant and a third binder;

[0056] The first solute and the second solute are independently selected from metal powders, and the third solute is selected from a mixed powder of metal powders and electrolyte ceramic powders;

[0057] The first solvent, the second solvent and the third solvent are selected from the same solvent;

[0058] The second adhesive and the third adhesive are made of the same material, while the first adhesive and the second adhesive are made of different materials;

[0059] The solid content of the sacrificial layer slurry is greater than the solid content of the supporting layer slurry and greater than the solid content of the transition layer slurry.

[0060] In the process of preparing the composite support of the solid oxide fuel cell, the present application firstly prepares a sacrificial layer slurry, a support layer slurry and a transition layer slurry.

[0061] The sacrificial layer slurry includes a first solvent, a first solute, a first dispersant, and a first binder; wherein the first solvent is selected from one or more of 1-methyl-2-pyrrolidone, ethanol, and propanol, specifically, the first solvent is selected from 1-methyl-2-pyrrolidone, ethanol, or propanol, in a specific embodiment, the first solvent is selected from 1-methyl-2-pyrrolidone; the first solute is metal powder, specifically, the metal powder is selected from one or more of 430L powder, Fe-Cr-Ni alloy powder, and P434L powder, more specifically, the metal powder is selected from one of 430L powder, Fe-Cr-Ni alloy powder, and P434L powder. In a specific embodiment, the metal powder is selected from 430L powder; the first dispersant is selected from one or more of polyvinyl pyrrolidone, triethanolamine, polyethylene glycol, oleic acid and acetone, specifically, the first dispersant is selected from one or two of polyvinyl pyrrolidone, triethanolamine, polyethylene glycol, oleic acid and acetone, in a specific embodiment, the first dispersant is selected from polyvinyl pyrrolidone and triethanolamine; the first binder is selected from one or more of polyether sulfone, polyvinyl butyral, polypropylene and polyvinyl alcohol, specifically, the first binder is selected from one of polyether sulfone, polyvinyl butyral, polypropylene and polyvinyl alcohol, in a specific embodiment, the first binder is selected from polyether sulfone or polypropylene.

[0062] The supporting layer slurry includes a second solvent, a second solute, a second dispersant and a second binder; wherein the second solvent is selected from one or more of 1-methyl-2-pyrrolidone, ethanol and propanol, specifically, the second solvent is selected from 1-methyl-2-pyrrolidone, ethanol or propanol, in a specific embodiment, the second solvent is selected from 1-methyl-2-pyrrolidone; the second solute is metal powder, specifically, the metal powder is selected from one or more of 430L powder, Fe-Cr-Ni alloy powder and P434L powder, more specifically, the metal powder is selected from one of 430L powder, Fe-Cr-Ni alloy powder and P434L powder, in a specific embodiment, the second solvent is selected from 1-methyl-2-pyrrolidone; the second solute is metal powder, specifically, the metal powder is selected from one or more of 430L powder, Fe-Cr-Ni alloy powder and P434L powder, In a specific embodiment, the metal powder is selected from 430L powder; the second dispersant is selected from one or more of polyvinyl pyrrolidone, triethanolamine, polyethylene glycol, oleic acid, and acetone. Specifically, the second dispersant is selected from one or two of polyvinyl pyrrolidone, triethanolamine, polyethylene glycol, oleic acid, and acetone. In a specific embodiment, the second dispersant is selected from polyvinyl pyrrolidone and triethanolamine. The second binder is selected from one or more of polyether sulfone, polyvinyl butyral, polypropylene, and polyvinyl alcohol. Specifically, the second binder is selected from one of polyether sulfone, polyvinyl butyral, polypropylene, and polyvinyl alcohol. In a specific embodiment, the second binder is selected from polyvinyl butyral. The support layer slurry also includes a first pore-forming agent, which is selected from one or more of starch, PMMA, and graphite. The pore-forming agent can be added as needed.

[0063] The transition layer slurry includes a third solvent, a third solute, a third dispersant and a third binder; wherein the third solvent is selected from one or more of 1-methyl-2-pyrrolidone, ethanol and propanol, specifically, the third solvent is selected from 1-methyl-2-pyrrolidone, ethanol or propanol, in a specific embodiment, the third solvent is selected from 1-methyl-2-pyrrolidone; the third solute is selected from a mixed powder of metal powder and electrolyte ceramic powder; the metal powder is selected from one or more of 430L powder, Fe-Cr-Ni alloy powder and P434L powder, and the electrolyte ceramic powder is selected from SSZ, YSZ, SDC, GDC, L One or more of SGM and BZCY; specifically, the metal powder is selected from one of 430L powder, Fe-Cr-Ni alloy powder and P434L powder, and the electrolyte ceramic powder is selected from one of SSZ, YSZ, SDC, GDC, LSGM and BZCY; in a specific embodiment, the third solute is selected from a mixed powder of 430L powder and SSZ powder, or a mixed powder of 430L powder and YSZ powder; the content of metal powder in the third solute is 10~90wt%, specifically, the content of metal powder is 20~80wt%, more specifically, the content of metal powder is 50~80wt%. The third dispersant is selected from one or more of polyvinyl pyrrolidone, acrylic resin, triethanolamine, and unsaturated polycarboxylic acid. Specifically, the third dispersant is selected from one or two of these. In a specific embodiment, the third dispersant is selected from polyvinyl pyrrolidone and unsaturated polycarboxylic acid to ensure more uniform dispersion of metal and ceramic powders. The third binder is selected from one or two of polyvinyl butyral and polyether sulfone. Specifically, the third binder is selected from polyvinyl butyral. The transition layer slurry also includes a second pore-forming agent selected from one or more of starch, PMMA, and graphite. The pore-forming agent can be added as needed.

[0064] Since the present application adopts a multi-layer phase inversion casting method to prepare the sacrificial layer, the support layer and the transition layer, in the present application, the solvents of the first solvent, the second solvent and the third solvent are selected to be the same. During the phase inversion process, the solvent and water will exchange to form a phase inversion structure. If the solvents of each layer are mixed differently, the phase separation rates of each layer will easily differ, resulting in poor interlayer bonding, and even the mutual diffusion of solvents between different layers will affect the uniformity of the formed body.

[0065] The materials of the first adhesive and the second adhesive are selected to be different, so that the sacrificial layer forms a phase transformation blank different from the latter two layers and has different swelling properties. After the phase transformation, the sacrificial layer has the structure of a sponge layer and does not have open straight pores. The open straight pores can be directly exposed by removing the sacrificial layer without the step of mechanical polishing to expose the straight pores; the materials of the second adhesive and the third adhesive are selected to be the same to ensure that the swelling properties of the transition layer and the support layer are consistent, and the two layers are tightly combined and will not be delaminated due to different compositions.

[0066] In the sacrificial layer slurry, the content of the first solvent is 25-35wt%, the content of the first solute is 55-70wt%, the content of the first dispersant is 0.5-5wt%, and the content of the first binder is 2-10wt%. Specifically, the content of the first solvent is 27-33wt%, the content of the first solute is 58-68wt%, the content of the first dispersant is 0.9-4.0wt%, and the content of the first binder is 3-8wt%. More specifically, the content of the first solvent is 28-31wt%, the content of the first solute is 60-65wt%, the content of the first dispersant is 1.6-3.3wt%, and the content of the first binder is 4.3-7.2wt%. More specifically, the content of the first solvent is 29-30wt%, the content of the first solute is 62-64wt%, the content of the first dispersant is 2.3-2.8wt%, and the content of the first binder is 5.4-6.5wt%.

[0067] In the supporting layer slurry, the content of the second solvent is 30~40wt%, the content of the second solute is 50~65wt%, the content of the second dispersant is 0.5~5wt%, the content of the second binder is 2~10wt%, and the content of the first pore-forming agent is 0~10wt%; specifically, the content of the second solvent is 32~38wt%, the content of the second solute is 53~62wt%, the content of the second dispersant is 0.8~4.1wt%, and the content of the second binder is 3~8wt%; more specifically, the content of the second solvent is 34~36wt%, the content of the second solute is 54~59wt%, the content of the second dispersant is 2.2~3.6wt%, and the content of the second binder is 4~6.2wt%.

[0068] In the transition layer slurry, the content of the third solvent is 35~45wt%, the content of the third solute is 45~60wt%, the content of the third dispersant is 0.5~5wt%, the content of the third binder is 2~10wt%, and the content of the second pore-forming agent is 0~10wt%; specifically, the content of the third solvent is 38~43wt%, the content of the third solute is 48~57wt%, the content of the third dispersant is 0.7~4.9wt%, and the content of the third binder is 3~8wt%; more specifically, the content of the third solvent is 39~42wt%, the content of the third solute is 49~52wt%, the content of the third dispersant is 1.0~3.8wt%, and the content of the third binder is 5~7wt%.

[0069] Furthermore, the solid content of the sacrificial layer slurry is greater than the solid content of the supporting layer slurry and greater than the solid content of the transition layer slurry; at the same time, the viscosity of the sacrificial layer slurry is greater than the viscosity of the supporting layer slurry and greater than the viscosity of the transition layer slurry. When the sacrificial layer, the supporting layer and the transition layer are co-cast, the sacrificial layer is at the bottom, the supporting layer is in the middle, and the transition layer is at the surface. The viscosity is regulated so that the mutual diffusion and exchange between the lower and upper slurries will not affect the flatness and uniformity of the cast film. If the supporting layer slurry is The viscosity of the material is lower than that of the transition layer slurry. During the casting process, the support layer slurry will float up and diffuse and exchange with the transition layer. When placed in water for phase transformation, it will cause the phase transformation film to be wrinkled, shapeless, and uneven. At the same time, the viscosity of the slurry is mainly regulated by the solvent and the binder, and it will also affect the pore size of the phase transformation straight holes. The thinner the pore size, the larger the pore size. The binder is related to the film formation of the green body. Sufficient binder is required to solidify the green body, otherwise it cannot be solidified into a film. However, too much binder will affect the sintering and debinding process of the green body, and will also affect the viscosity of the slurry.

[0070] The preparation of the above three layers of slurry determines the successful preparation of multi-layer phase inversion casting. After the above three layers of slurry are prepared, it is preferred to degas the sacrificial layer slurry, the supporting layer slurry and the transition layer slurry respectively to remove the air in the above layers of slurry respectively; the degassing time of the above layers of slurry is independently 10~60min, specifically, the degassing time of the above layers of slurry is independently 20~30min. After the above degassing treatment, the sacrificial layer slurry, support layer slurry and transition layer slurry are placed in a casting machine in the order of sacrificial layer slurry, with the sacrificial layer slurry placed at the bottom. After casting, the obtained green body is subjected to phase inversion solidification in a water bath, and the sacrificial layer is removed to obtain a composite support body. In the above process, the casting machine is well known to those skilled in the art and is not particularly limited in this application. During the casting, the thickness of the sacrificial layer is 400-800 μm, the thickness of the support layer is 300-800 μm, and the thickness of the transition layer is 100-200 μm. The casting temperature is 20-30°C and the speed is 8-15 cm / min. After the phase transition, a sponge layer, a finger hole layer and a skin layer will be formed in the green body. The present application requires a finger hole layer and a skin layer. The thickness of each of the above layers is adjusted to achieve that the sacrificial layer is in the sponge layer and finger hole layer of the phase transition green body, the support layer is in the finger hole layer, and the transition layer is in the skin layer. The water bath temperature is 20-30°C for 12-36 hours. During this process, due to differences in concentration and solute mass, the solute in the transition layer forms a concentration gradient, with the topmost layer containing more electrolyte powder and the bottom layer containing more metal powder. The formation of finger-like pores during phase transformation also contributes to the formation of a concentration gradient structure. After the green body solidifies, the sacrificial layer separated by swelling is removed, and the support layer is polished to expose the finger-like pores, resulting in a composite support with a concentration gradient transition layer.

[0071] The composite support body prepared by the above-mentioned preparation method of the present application includes a support layer and a transition layer. The support layer has a finger-like pore structure, and the large pores are exposed to the air without obvious closed pores; the transition layer has a concentration gradient distribution, and the metal powder content near the support layer end is higher than the metal powder content at the far support layer end, and the electrolyte powder content near the support layer end is lower than the electrolyte powder content at the far support layer end. The pores near the support layer end are fine and dense, and the pores at the far support layer end are larger and also present a gradient distribution.

[0072] The present application also provides a solid oxide fuel cell, comprising a cathode, an electrolyte, a support and an anode, wherein the support is prepared by the preparation method described in the above scheme or the composite support described in the above scheme, and the electrolyte is in contact with the transition layer of the support.

[0073] Furthermore, the present application also provides a method for preparing a solid oxide fuel cell, comprising the following steps:

[0074] The electrolyte was prepared by tape casting;

[0075] Preheating and pre-pressing a support, stacking the pre-pressed support and the electrolyte, preheating, and then pressing, wherein the support is prepared by the preparation method described in the above scheme or the composite support described in the above scheme, and the electrolyte is in contact with the transition layer of the support;

[0076] The pressed half-cell is debinded and then sintered, and then a cathode and an anode are respectively prepared on both sides of the sintered half-cell to obtain a solid oxide fuel cell.

[0077] The preparation process of the solid oxide fuel cell of this application is as follows Figure 1 As shown, it includes the following steps: preparing multi-layer casting slurry - placing multi-layer casting slurry - casting - phase conversion solidification - removing sacrificial layer - pre-pressing support body - placing electrolyte, pre-pressing - sintering - full battery.

[0078] Specifically, the electrolyte is first prepared by a tape casting method, and the electrolyte slurry of the tape casting method includes ceramic powder, solvent, binder, plasticizer and dispersant. The ceramic powder is selected from one or more of SSZ, YSZ, SDC, GDC, LSCM and BZCY, and the content is 45~60wt%. Specifically, the ceramic powder is selected from one of SSZ, YSZ, SDC, GDC, LSCM and BZCY; the solvent is selected from one or more of anhydrous ethanol, xylene, butyl acetate and butanone. Specifically, the solvent is selected from one or two of anhydrous ethanol, xylene, butyl acetate and butanone. In a specific embodiment, the solvent is selected from anhydrous ethanol and xylene, and the content is 30~40wt%; the binder is selected from one or more of polyvinyl butyral and epoxy resin. Multiple, content is 2~10wt%, specifically, the binder is selected from polyvinyl butyral; the plasticizer is selected from one or more of polyethylene glycol, phthalate diester and polyethylene oxide, specifically, the plasticizer is selected from one of polyethylene glycol, phthalate diester and polyethylene oxide, in a specific embodiment, the plasticizer is selected from phthalate diester, content is 2~8wt%; the dispersant is selected from one or more of triethanolamine, acrylic resin and oleic acid, specifically, the dispersant is selected from one of triethanolamine, acrylic resin and oleic acid, in a specific embodiment, the dispersant is selected from acrylic resin, content is 0.5~4wt%. In this application, the ceramic powder in the electrolyte is the same as the ceramic powder in the transition layer in the composite support. The preparation of the electrolyte casting method is well known to those skilled in the art, and this application does not impose any special restrictions on this; the thickness of the electrolyte is 10~30μm, specifically, the thickness of the electrolyte is 20~25μm. Specifically, the content of the ceramic powder is 48~58%, the content of the solvent is 33~38%, the content of the binder is 3~8%, the content of the plasticizer is 2.8~6.2%, and the content of the dispersant is 0.8~3.1%; more specifically, the content of the ceramic powder is 50~56%, the content of the solvent is 34~36%, the content of the binder is 5.6~7.8%, the content of the plasticizer is 3.2~5.4%, and the content of the dispersant is 1.7~2.5%.

[0079] This application then preheats the support and pre-presses it, the preheating temperature is 60~85℃, the time is 5~30min, the pre-pressing pressure is 5~10MPa, and the time is 30s~50min; specifically, the preheating temperature is 65~75℃, the time is 10~20min, the pre-pressing pressure is 5~8MPa, and the time is 1min~20min. After the support is pre-pressed, it is stacked with the electrolyte and then preheated and pressed, the preheating temperature is 60~85℃, the time is 5~30min, the pressing pressure is 5~30MPa, and the time is 1~10min; specifically, the preheating temperature is 65~75℃, the time is 10~20min, the pressing pressure is 10~20MPa, and the time is 5~8min.

[0080] During the above-mentioned pre-pressing process, the support body is limited in height, and the height limit is 80-90% of the support body height. Similarly, during the above-mentioned pressing process, the stacked pre-pressed support body and electrolyte are limited in height, and the height limit is 70-90% of the pre-pressed support body.

[0081] According to the present invention, the pressed half-cell is debinded and then sintered. The debinding temperature is 200-600°C, and the heating rate is 0.1-1°C / min. Specifically, the debinding temperature is 300-400°C, and the heating rate is 0.3-0.8°C / min. The sintering temperature is 1300-1500°C, and the time is 2-6 hours. The sintering atmosphere is selected from 10% H2-90% Ar, 5% H2-95% Ar, 10% H2-90% N2, or 5% H2-95% N2. Specifically, the sintering temperature is 1380-1450°C, and the time is 3-4 hours.

[0082] Furthermore, the present application prepares a functional layer on the electrolyte surface of the sintered half-cell, and the slurry for preparing the functional layer includes ceramic powder, solvent and dispersant. Wherein, the ceramic powder is selected from one or more of SSZ, YSZ, SDC, GDC, LSCM and BZCY. Specifically, the ceramic powder is selected from one of SSZ, YSZ, SDC, GDC, LSCM and BZCY. In a specific embodiment, the ceramic powder is selected from SDC; the content of the ceramic powder is 5-20wt%; the solvent is selected from one or more of anhydrous ethanol, propanol, N-methylpyrrolidone and butanone. Specifically, the solvent is selected from one of anhydrous ethanol, propanol, N-methylpyrrolidone and butanone. In a specific embodiment, the solvent is selected from anhydrous ethanol, and the content of the solvent is 70-90wt%; the dispersant is selected from one or more of polyethylene glycol, Triton X-100 and ammonium polyacrylate. Specifically, the dispersant is selected from one of polyethylene glycol, Triton X-100 and ammonium polyacrylate. In a specific embodiment, the dispersant is selected from polyethylene glycol, and the content of the dispersant is 2-10wt%. Specifically, the content of the ceramic powder is 8-16%, the content of the solvent is 72-87%, and the content of the dispersant is 3-8%; more specifically, the content of the ceramic powder is 9-13%, the content of the solvent is 76-82%, and the content of the dispersant is 4-6%. The solid content of the prepared slurry is 5-20%. The functional layer is prepared according to methods well known to those skilled in the art, and this application does not impose any particular restrictions on this. For example, the functional layer slurry is spin-coated on the electrolyte surface, dried, and then sintered at high temperature.

[0083] Finally, the present application prepares the cathode and anode on both sides of the half-cell respectively to obtain a solid oxide fuel cell, wherein the cathode is in contact with the electrolyte and the anode is attached to the surface of the support skeleton; in this process, the cathode and the anode are well known to those skilled in the art, and the present application does not impose any special restrictions on this.

[0084] In order to further understand the present invention, the solid oxide fuel cell composite support, its preparation method and solid oxide fuel cell provided by the present invention are described in detail below in conjunction with the examples. The scope of protection of the present invention is not limited by the following examples.

[0085] Example 1

[0086] (1) Preparation of tape-cast composite support slurry

[0087] Prepare three types of tape casting slurries: sacrificial layer, support layer and transition layer:

[0088] The sacrificial layer slurry composition is as follows: solvent 1-methyl-2-pyrrolidone 100g, solute 430L stainless steel powder 240g, dispersants polyvinylpyrrolidone 5g and triethanolamine 4g, binder polyethersulfone 20g;

[0089] The supporting layer slurry composition is as follows: solvent 1-methyl-2-pyrrolidone 130g, solute 430L stainless steel powder 240g, dispersants polyvinyl pyrrolidone 5g and triethanolamine 4g, binder polyvinyl butyral 25g;

[0090] The transition layer slurry composition is as follows: solvent 1-methyl-2-pyrrolidone 80g, solute 430L stainless steel powder 80g and SSZ powder 20g, dispersant polyvinyl pyrrolidone 4g and unsaturated polycarboxylic acid 6g, binder polyvinyl butyral 15g;

[0091] The prepared slurries were ball-milled for 24 hours to mix evenly, and then degassed in a vacuum degassing machine for 30 minutes to remove air, thereby obtaining sacrificial layer slurry, support layer slurry, and transition layer slurry respectively.

[0092] (2) Three-layer phase transition casting

[0093] A phase transition support with a gradient structure was prepared by a multilayer casting method:

[0094] Turn on the casting machine, set the speed to 10 cm / min, the casting temperature to 25°C, pour the sacrificial layer slurry, the supporting layer slurry, and the transition layer slurry in turn for casting, wherein the thickness of each layer is adjusted by adjusting the height of different scrapers, wherein the scraper height of the sacrificial layer at the bottom layer is 500 μm, the scraper height of the supporting layer in the middle layer is 1000 μm, and the scraper height of the transition layer at the top layer is 1100 μm; the cast green body is kept in a water bath for 24 hours at a water bath temperature of 20°C, and the green body is allowed to phase invert and solidify to form a gradient pore structure. After tearing off the sacrificial layer, the sacrificial layer surface is polished flat with a grinding plate to obtain a composite support green body with a gradient pore structure having a supporting layer and a transition layer, which is dried at room temperature for 24 hours for use;

[0095] (3) Electrolyte preparation

[0096] Preparation of electrolyte green body by tape casting:

[0097] Prepare electrolyte slurry by mixing 50g of SSZ powder, 15g of anhydrous ethanol, 15g of xylene, 1.5g of dispersed acrylic resin, 2.5g of dibutyl phthalate, and 5g of polyvinyl butyral by planetary ball milling for 4h to obtain an electrolyte slurry. Degas in a vacuum degassing machine for 20min to remove air before use. Then, tape-cast the electrolyte slurry with a scraper height of 100μm and dry it at 50°C to obtain a 20μm thick electrolyte slurry for use.

[0098] (4) Hot pressing process

[0099] The gradient structure composite support was pre-pressed. The support was cut into 15cm*15cm pieces and sealed, with the transition layer facing the flat surface of the backing plate and a height limit of 500μm. It was preheated in a hot press at 75°C for 20 minutes, followed by pre-pressing at 5MPa for 1 minute to obtain a composite support with a flat transition layer. The cut electrolyte and the composite support were then stacked, with the electrolyte in contact with the transition layer of the composite support, with the electrolyte facing the backing plate and a height limit of 400μm. It was preheated in a hot press at 75°C for 20 minutes, and then pressed at 10MPa for 5 minutes.

[0100] (5) Half-cell sintering process

[0101] The hot-pressed battery was cut into 1.5 cm Φ discs and debinded in a muffle furnace at 600 °C with a heating rate of 0.5 °C / min for 5 h. The battery was then sintered to 1380 °C in a 10% H2-90% Ar protective atmosphere and kept at this temperature for 4 h to obtain a half-cell with a dense electrolyte.

[0102] (6) Full battery preparation process

[0103] A terpineol slurry for the PBSC-SDC cathode was prepared, in which the ratio of PBSC, SDC and terpineol was 7:3:10 respectively. The evenly mixed cathode slurry was screen-printed on the surface of the half-cell. The anode metal support side was impregnated with a nitrate solution of NiO-SDC with a molar concentration of 0.2 mol / L and then calcined at 600°C until the impregnation reached 5% of the skeleton mass to obtain a full battery.

[0104] Example 2

[0105] Method for preparing a metal-supported battery with an electrolyte functional layer:

[0106] The preparation method is basically the same as that of Example 1, except that the sintering process of the half-cell in step (5) is as follows:

[0107] The hot-pressed battery Φ1.5cm disc was subjected to binder removal treatment at 600℃ for 5h in a muffle furnace, and then the battery was placed in a 10%H2-90%Ar protective atmosphere and sintered to 1200℃ and kept at this temperature for 2h to obtain a half-cell body.

[0108] The electrolyte functional layer coating process is performed on the sintered half-cell body: 20g of SDC ceramic powder, 200g of solvent anhydrous ethanol and 10g of dispersant polyethylene glycol are mixed evenly by roller ball milling or planetary ball milling. The prepared electrolyte functional layer slurry is spin-coated on the electrolyte surface and dried at room temperature. Spin-coating is performed 2 to 4 times.

[0109] The coated battery was sintered at high temperature, with a sintering temperature of 1380°C, a sintering time of 4 hours, and a sintering atmosphere of 10% H2-90% Ar.

[0110] Example 3

[0111] The preparation method is basically the same as that of Example 1, except that the ratio of ceramic powder to metal powder in the transition layer is different, specifically:

[0112] The transition layer slurry composition is: solvent 1-methyl-2-pyrrolidone 80g, solute 430L stainless steel powder 50g and SSZ powder 50g, dispersant polyvinyl pyrrolidone 4g and unsaturated polycarboxylic acid 6g, binder polyvinyl butyral 15g.

[0113] Example 4

[0114] The preparation method is basically the same as that of Example 1, except that the ceramic powders of the transition layer and the electrolyte are different, specifically:

[0115] The transition layer slurry composition is: solvent 1-methyl-2-pyrrolidone 80g, solute 430L stainless steel powder 80g and YSZ powder 20g, dispersant polyvinyl pyrrolidone 4g and unsaturated polycarboxylic acid 6g, binder polyvinyl butyral 15g.

[0116] The electrolyte slurry composition is: solute YSZ powder 50g, solvent anhydrous ethanol 15g and xylene 15g, dispersant dispersed acrylic resin 1.5g, plasticizer dibutyl phthalate 2.5g, binder polyvinyl butyral 5g.

[0117] Example 5

[0118] The preparation method is basically the same as that of Example 1, except that the adhesive used in the sacrificial layer is different, specifically:

[0119] The composition of the sacrificial layer slurry is as follows: the solvent is 100 g of 1-methyl-2-pyrrolidone, the solute is 240 g of 430L stainless steel powder, the dispersants are 5 g of polyvinylpyrrolidone and 4 g of triethanolamine, and the binder is 20 g of polypropylene.

[0120] Comparative Example 1

[0121] The preparation method is basically the same as that of Example 1, except that the binder and slurry used in the sacrificial layer, support layer, and transition layer have different contents of some components, specifically:

[0122] The sacrificial layer slurry composition is: solvent 1-methyl-2-pyrrolidone 110g, solute 430L stainless steel powder 240g, dispersants polyvinyl pyrrolidone 5g and triethanolamine 4g, binder polyvinyl butyral 25g;

[0123] The supporting layer slurry composition is: solvent 1-methyl-2-pyrrolidone 110g, solute 430L stainless steel powder 240g, dispersants polyvinylpyrrolidone 5g and triethanolamine 4g, binder polyethersulfone 20g;

[0124] The transition layer slurry composition is: solvent 1-methyl-2-pyrrolidone 70g, solute 430L stainless steel powder 80g and SSZ powder 20g, dispersant polyvinylpyrrolidone 3g and unsaturated polycarboxylic acid 5g, binder polyethersulfone 10g.

[0125] Comparative Example 2

[0126] The preparation method is basically the same as that of Example 1, except that the support is a double-layer cast metal support, and the transition layer is a transition layer prepared by ordinary casting. The transition layer is first laminated on the support by the same hot pressing method as the electrolyte, and then the electrolyte is laminated. In addition, due to the change of the transition layer, the debinding process of the green body is also changed, specifically:

[0127] The slurry composition of the ordinary cast transition layer is: solvent xylene 15g, butyl acetate 15g, solute 430L powder 40g, SSZ powder 10g, ammonium oxalate 25g, dispersant unsaturated polycarboxylic acid 1g, dispersed acrylic resin 2.5g, plasticizer is non-ophthalic plasticizer 3g, binder is acrylic resin 5g, after planetary ball milling for 4h, vacuum degassing for 30min before use.

[0128] During hot pressing, the metal support and the transition layer are first stacked, with the hot pressing parameters of temperature 75°C, pressure 5 MPa, and time 1 min, and then the electrolyte layer is stacked on the surface of the transition layer, with the hot pressing parameters of temperature 75°C, pressure 10 MPa, and time 5 min.

[0129] When preparing and using the transition layer, the environment must be dry and the relative humidity must be less than 50% to prevent ammonium oxalate from absorbing moisture.

[0130] During debinding, the hot-pressed battery was cut into Φ1.5 cm discs, debinded in a muffle furnace, heated to 200°C at a temperature of 50°C and a heating rate of 0.2°C / min, and kept warm for 5 hours. Then, the temperature was raised to 600°C at a temperature of 200°C and a heating rate of 0.5°C / min, and kept warm for 5 hours. The battery was then placed in a 10% H2-90% Ar protective atmosphere and sintered to 1380°C, and kept warm for 4 hours to obtain a half-cell with a dense electrolyte.

[0131] The above examples and comparative examples are analyzed, and the specific analysis is as follows:

[0132] 1) Phase inversion preparation of solid oxide fuel cells containing concentration gradient transition layers

[0133] like Figure 1 As shown, Figure 1 The process flow diagram of the preparation method of solid oxide fuel cell with gradient transition layer is shown in FIG. Figure 1 The solid oxide fuel cell is prepared by the method shown in FIG. Figure 2 As shown in (a), the support layer has finger-shaped macropores, which play the role of structural support and gas diffusion channel. The transition layer has a concentration gradient structure. The transition layer close to the electrolyte has a higher SSZ content. Because SSZ powder is lighter than 430L powder, the transition layer slurry is thinner and suspended in the upper layer, while 430L sinks to the lower layer. Due to the viscous fingering effect of the phase transformation process, the pores in the upper layer are fine and dense, while the pores in the lower layer are larger, also forming a gradient distribution.

[0134] The cross-sectional structure of the solid oxide fuel cell prepared in Example 1 is as follows: Figure 3 As shown, Figure 3 (b) shows the overall cross-sectional structure of a solid oxide fuel cell, showing the cell's four layers: cathode layer, electrolyte layer, transition layer, and support layer. The transition layer is 50 μm thick, the support layer is 350 μm thick, the electrolyte is 15 μm, and the cathode is 20 μm. The support layer has finger-like through-holes, and these macropores are exposed to air without obvious closed pores, providing good flow channels for gas transport. Figure 3 (a) is a cross-sectional view near the electrolyte. As shown in the figure, the electrolyte is dense and well bonded to the transition layer. The transition layer has an obvious gradient structure. The SSZ content near the electrolyte is relatively high, tightly bonded to the electrolyte, and has a loose pore structure to ensure the three-phase interface of the battery reaction. The particles near the lower layer are larger in size, the main component is 430L, and are tightly bonded to the support.

[0135] The actual photo of the large-scale half-cell prepared in Example 1 is as follows: Figure 4 As shown by Figure 4 It can be seen that the battery surface is flat, the electrolyte is tightly bonded to the supporting electrode, and the battery diameter is Φ2.4 cm, which has application prospects in the preparation of large-size batteries.

[0136] The solid oxide fuel cell prepared in Example 1 was encapsulated in a sealed device, and the two sides were placed in 97% H2-3% H2O and static air respectively for electrochemical performance testing. The maximum power density of the battery prepared in Example 1 at each temperature range is shown in the figure below. Figure 6 As shown by Figure 6 It can be seen that the maximum power density of the battery from 550℃ to 700℃ is 0.20W / cm 2 , 0.40W / cm 2 , 0.71W / cm 2 , 1.15W / cm 2, it can be seen that the solid oxide fuel cell prepared in Example 1 has higher electrochemical performance.

[0137] 2) Metal-supported batteries with electrolyte functional layers

[0138] A functional layer is coated on the electrolyte to protect the electrolyte and avoid side reactions between the cathode and the electrolyte. The schematic diagram of the prepared battery structure is shown in the figure. Figure 2 As shown in (b), there is a functional layer on the upper layer of the electrolyte to avoid direct contact between the cathode and the electrolyte; the support layer has finger-shaped large pores, which play the role of structural support and gas diffusion channel, and the transition layer has a concentration gradient structure. The transition layer close to the electrolyte has a higher SSZ content. Because SSZ powder is lighter than 430L powder, the transition layer slurry is thinner and suspended in the upper layer, and 430L sinks to the lower layer. Due to the viscous fingering effect of the phase transformation process, the pores in the upper layer are fine and dense, and the pores in the lower layer are larger, and also present a gradient distribution.

[0139] The cross section of the solid oxide fuel cell prepared in Example 2 near the electrolyte is as follows Figure 5 As shown in the figure, the electrolyte is dense, with a 5μm thick SDC functional layer on the upper layer, which is well bonded to the electrolyte and cathode. The electrolyte is well bonded to the lower transition layer, and the transition layer has a clear gradient structure. The SSZ content near the electrolyte is relatively high, tightly bonded to the electrolyte, and has a loose pore structure to ensure the three-phase interface of the battery reaction. The grain size near the lower layer is larger, the main component is 430L, and it is tightly bonded to the support. The electrochemical performance of the prepared battery with an electrolyte functional layer was also tested, and the battery had good stability and high electrochemical performance.

[0140] 3) Metal-supported batteries with different transition layer ratios

[0141] The metal-supported battery prepared in Example 3 differs from that in Example 1 in that the ratio of ceramic powder to metal powder in the transition layer is different. The mass ratio of metal powder to ceramic powder in the transition layer of this application can be adjusted within the range of (1:9 < metal:ceramic < 9:1). The solid oxide fuel cell prepared in Example 3 still has a concentration gradient transition layer. The SSZ electrolyte content in the transition layer is higher than that in the battery of Example 1. The transition layer is tightly bonded to the electrolyte, as shown in FIG. Figure 7 In the fuel cell test, the battery prepared in Example 3 also has good electrochemical performance, but due to the reduction of the 430L metal ratio in the transition layer, the electronic conductivity of the transition layer decreases, and the maximum power density at 700°C is 0.9W / cm 2 , which is less than the performance of the battery prepared in Example 1.

[0142] 4) Metal-supported batteries with different electrolytes

[0143] The battery prepared in Example 4 differs from the battery prepared in Example 1 in that the electrolyte material is replaced with YSZ. Replacing different electrolytes requires replacing the electrolyte ceramic in the transition layer to ensure that the transition layer and the electrolyte are bonded. The transition layer structure of the metal-supported battery prepared in Example 4 is the same as that in Example 1. The ceramic powder is concentrated near the electrolyte side, which bonds well with the electrolyte, and the metal content is higher near the support layer side. The prepared battery fuel cell test shows good electrochemical performance, with a maximum power density of 0.8W / cm at 700°C. 2 .

[0144] 5) Metal-supported batteries prepared with different sacrificial layer binders

[0145] The battery prepared in Example 5 is different from that in Example 1 in that: the sacrificial layer binder is different; the binder used in Example 5 is polypropylene; the sacrificial layer and the support layer of the phase transformation body prepared in Example 5 use different binders, but can still be cast due to the different swelling properties caused by the different binders of the two layers; the sacrificial layer prepared with polypropylene binder can also be separated from the support layer, exposing the straight holes of the support layer, but when using polypropylene, a small amount of sacrificial layer body will remain on the surface of the support layer, and the surface sacrificial layer body needs to be polished to remove.

[0146] 6) Metal-supported batteries with different sacrificial layer, support layer, and transition layer binder compositions

[0147] The binder used in the support prepared in Comparative Example 1 is interchanged with that in Example 1, and the prepared phase transformation body can also obtain an open straight-pore body with a transition layer structure, but compared with the body with the support layer and the transition layer polyvinyl butyral binder, the pore size of the polyethersulfone body is smaller. After hot pressing the electrolyte, due to the high softening temperature of polyethersulfone, the hot pressing temperature of 75°C cannot completely combine the electrolyte film with the transition layer; after sintering, there is obvious stratification of the electrolyte and the support body; on this basis, it is necessary to increase the hot pressing temperature or change the hot pressing method to ensure that the electrolyte is completely compatible with the organic matter in the transition layer.

[0148] 7) Metal-supported battery using transition layer prepared by ordinary casting

[0149] The transition layer of the metal-supported battery prepared in Comparative Example 2 was prepared by ordinary casting. In this method, the pore-forming agent ammonium oxalate needs to be added to the transition layer to ensure the porosity of the transition layer structure. Compared with the phase-inversion three-layer casting, no pore-forming agent needs to be added, and the transition layer still has a high porosity. Moreover, after adding the pore-forming agent ammonium oxalate, the preparation process is complicated, and a pore-forming agent discharge process of ammonium oxalate needs to be added. Dry conditions also need to be maintained during battery preparation to prevent ammonium oxalate from absorbing moisture.

[0150] The transition layer of the solid oxide fuel cell prepared in Comparative Example 2 has an obvious layered structure, such as Figure 8 As shown in the figure, the electrolyte and the support are clearly distinguished. Compared with the transition layer prepared by three-layer tape casting, the combination of the electrolyte and the transition layer is relatively poor, and the electrolyte is easily separated from the support. The maximum power density of the prepared metal support battery at 700°C is 0.7W / cm 2 Since the interface bonding is poorer than that of three-layer casting, the ohmic impedance of the battery is increased and the electrochemical performance is relatively reduced.

[0151] In summary, in the present invention, a multi-layer phase conversion casting method is used and a metal ceramic transition layer is set, and the composition and solid content of each layer of casting slurry are adjusted to prepare a solid oxide fuel cell with a concentration gradient transition layer; wherein, the electrolyte of the solid oxide fuel cell prepared in this application is tightly combined with the support layer through the transition layer, which can effectively resist impact stress, and the transition layer structure is loose and has rich three-phase interfaces, ultimately making the solid oxide fuel cell have higher electrochemical performance; further, a solid oxide fuel cell with a functional layer is prepared by coating, which has good long-term stability. The solid oxide fuel cell prepared in this application has the potential to be enlarged in size, which is conducive to industrialization and scale, and provides strong support for the application of MS-SOFC.

[0152] The above embodiments are only intended to help understand the method and core concept of the present invention. It should be noted that, without departing from the principles of the present invention, a number of improvements and modifications may be made to the present invention by those skilled in the art, and such improvements and modifications also fall within the scope of protection of the claims of the present invention.

[0153] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing a solid oxide fuel cell composite support, comprising the following steps: S1. Prepare sacrificial layer slurry, support layer slurry and transition layer slurry; S2. Place the sacrificial layer slurry, support layer slurry, and transition layer slurry in a tape casting machine in this order, with the sacrificial layer slurry placed at the bottom. After tape casting, phase inversion solidify the resulting green body in a water bath, remove the sacrificial layer, and obtain a composite support body. The sacrificial layer slurry includes a first solvent, a first solute, a first dispersant and a first binder; The supporting layer slurry includes a second solvent, a second solute, a second dispersant and a second binder; The transition layer slurry includes a third solvent, a third solute, a third dispersant and a third binder; The first solute and the second solute are independently selected from metal powders, and the third solute is selected from a mixed powder of metal powder and electrolyte ceramic powder; the metal powder is selected from one or more of 430L powder, Fe-Cr-Ni alloy powder and P434L powder; The first solvent, the second solvent and the third solvent are the same; the first solvent, the second solvent and the third solvent are selected from one or more of 1-methyl-2-pyrrolidone, ethanol and propanol; The second binder and the third binder are the same, and the first binder and the second binder are different; The solid content of the sacrificial layer slurry is greater than the solid content of the supporting layer slurry and greater than the solid content of the transition layer slurry.

2. The preparation method according to claim 1, characterized in that In the sacrificial layer slurry, the content of the first solvent is 25~35wt%, the content of the first solute is 55~70wt%, the content of the first dispersant is 0.5~5wt%, and the content of the first binder is 2~10wt%; and / or, in the supporting layer slurry, the content of the second solvent is 30~40wt%, the content of the second solute is 50~65wt%, the content of the second dispersant is 0.5~5wt%, and the content of the second binder is 2~10wt%; and / or, in the transition layer slurry, the content of the third solvent is 35~45wt%, the content of the third solute is 45~60wt%, the content of the third dispersant is 0.5~5wt%, and the content of the third binder is 2~10wt%.

3. The preparation method according to claim 1 or 2, characterized in that The electrolyte ceramic powder is selected from one or more of SSZ, YSZ, SDC, GDC, LSGM and BZCY.

4. The preparation method according to claim 1 or 2, characterized in that The first dispersant and the second dispersant are independently selected from one or more of polyvinyl pyrrolidone, triethanolamine, polyethylene glycol, oleic acid and acetone, and the third dispersant is selected from one or more of polyvinyl pyrrolidone, acrylic resin, triethanolamine and unsaturated polycarboxylic acid; and / or, the first binder is selected from one or more of polyethersulfone, polyvinyl butyral, polypropylene and polyvinyl alcohol; The second binder is selected from one or both of polyvinyl butyral and polyethersulfone.

5. The preparation method according to claim 1 or 2, characterized in that The temperature of the water bath is 20-30°C, and the curing time is 12-36 hours; And / or, during the casting process, the thickness of the sacrificial layer is 400-800 μm, the thickness of the support layer is 300-800 μm, and the thickness of the transition layer is 100-200 μm.

6. The composite support body prepared by the preparation method according to any one of claims 1 to 5, comprising a support layer and a transition layer, wherein the support layer has a finger-like pore structure, the second solute of the transition layer has a concentration gradient distribution, and the metal powder content near the support layer end is higher than the metal powder content at the distal support layer end, and the electrolyte powder content near the support layer end is lower than the electrolyte powder content at the distal support layer end.

7. A solid oxide fuel cell comprising a cathode, an electrolyte, a support and an anode, characterized in that: The support is prepared by the preparation method according to any one of claims 1 to 5 or the composite support according to claim 6, and the electrolyte is in contact with the transition layer of the support.

8. The method for preparing the solid oxide fuel cell according to claim 7, comprising the following steps: The electrolyte was prepared by tape casting; Preheating and pre-pressing a support, stacking the pre-pressed support and the electrolyte, preheating, and then pressing, wherein the support is prepared by the preparation method according to any one of claims 1 to 5 or the composite support according to claim 6, and the electrolyte is in contact with the transition layer of the support; The pressed half-cell is debinded and then sintered, and then a cathode and an anode are respectively prepared on both sides of the sintered half-cell to obtain a solid oxide fuel cell.

9. The preparation method according to claim 8, characterized in that The electrolyte slurry of the tape casting method includes ceramic powder, solvent, binder, plasticizer and dispersant; wherein the ceramic powder is selected from one or more of SSZ, YSZ, SDC, GDC, LSCM and BZCY, with a content of 45-60wt%; the solvent is selected from one or more of anhydrous ethanol, xylene, butyl acetate and butanone, with a content of 30-40wt%; the binder is selected from one or more of polyvinyl butyral and epoxy resin, with a content of 2-10wt%; the plasticizer is selected from one or more of polyethylene glycol, phthalate diester and polyethylene oxide, with a content of 2-8wt%; the dispersant is selected from one or more of triethanolamine, acrylic resin and oleic acid, with a content of 0.5-4wt%; And / or, the support is preheated at a temperature of 60-85° C. for 5-30 min, and pre-pressed at a pressure of 5-10 MPa for 30 s-50 min; And / or, the preheating temperature after stacking is 60-85° C., the time is 5-30 min, and the pressing pressure is 5-30 MPa, the time is 1-10 min; And / or, the debinding temperature is 200-600°C, and the heating rate is 0.1-1°C / min; And / or, the sintering temperature is 1300-1500° C., the time is 2-6 hours, and the sintering atmosphere is selected from 10% H2-90% Ar, 5% H2-95% Ar, 10% H2-90% N2 or 5% H2-95% N2.

10. The preparation method according to claim 8 or 9, characterized in that: After the sintering, the following steps are further included: preparing a functional layer on the electrolyte surface of the sintered half-cell; The preparation slurry of the functional layer includes ceramic powder, solvent and dispersant; the ceramic powder is selected from one or more of SSZ, YSZ, SDC, GDC, LSCM and BZCY, with a content of 5-20wt%, the solvent is selected from one or more of anhydrous ethanol, propanol, N-methylpyrrolidone and butanone, with a content of 70-90wt%, and the dispersant is selected from one or more of polyethylene glycol, Triton X-100 and ammonium polyacrylate, with a content of 2-10wt%; the solid content of the prepared slurry is 5-20%.

Images