Solid oxide fuel cell total cell and preparation method thereof
By optimizing the solvent system and hot-pressing composite process, the problems of bending deformation and poor interfacial bonding in the preparation of SOFC full cells were solved, achieving high flatness and excellent electrochemical performance, while reducing production costs and energy consumption.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SHANDONG XINHUANQING TECHNOLOGY DEVELOPMENT CO LTD
- Filing Date
- 2026-01-26
- Publication Date
- 2026-05-05
AI Technical Summary
In the existing technology, SOFC full cells have problems such as severe bending deformation, poor interface bonding, long preparation cycle and poor performance consistency during the preparation process. These problems are mainly due to the difference in thermal expansion coefficients of the materials of each functional layer and the mismatch in shrinkage behavior during sintering.
By employing a solvent system-differentiated design and hot-pressing composite process, and by optimizing the slurry formulation and solvent composition of each functional layer, combined with a multi-stage heating and sintering regime, the shrinkage behavior of each layer is matched and stress self-balanced. The hot-pressing composite process with stepped pressure is used to improve the interfacial bonding strength, reduce the risk of delamination, and shorten the preparation cycle.
The full cell curvature was reduced to below 1.0%, which improved the yield and interfacial bonding strength of the cells, reduced production costs, and enhanced electrochemical performance, with a maximum power density of over 1.2 W/cm².
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of solid oxide fuel cell technology, and particularly relates to a solid oxide fuel cell full cell and its preparation method. Background Technology
[0002] Solid oxide fuel cells (SOFCs) are efficient and environmentally friendly energy conversion devices that can directly convert chemical energy into electrical energy. Planar SOFCs have attracted much attention due to their high power density and relatively simple fabrication process. However, during the fabrication of SOFC full cells, the differences in the thermal expansion coefficients of the materials in each functional layer and the mismatch in shrinkage behavior during sintering often lead to bending deformation of the cells.
[0003] In the existing technology, SOFC full cells are usually prepared by casting to prepare the anode support, and then the anode functional layer, electrolyte layer and cathode layer are prepared sequentially by screen printing, spraying and other methods. Although this layer-by-layer preparation method is relatively mature, it has the following problems: (1) Severe bending deformation: Due to the different shrinkage rates of each layer material during drying and sintering, the cell generates internal stress, which in turn causes bending deformation. The bending degree is usually between 2% and 4%; (2) Poor interface bonding: When preparing layer by layer, the interface bonding strength between layers is insufficient, which easily leads to delamination of the cell during thermal cycling; (3) Long preparation cycle: Multiple drying and sintering are required, resulting in high energy consumption and low production efficiency; (4) Poor performance consistency: Bending deformation leads to poor contact of the cell during stack assembly, affecting the stability and consistency of the cell performance.
[0004] Therefore, developing a preparation method that can effectively control the flatness of SOFC full cells, improve the interfacial bonding strength, and shorten the preparation cycle is of great practical significance. Summary of the Invention
[0005] One objective of this invention is to provide a method for preparing a full cell of a solid oxide fuel cell, which effectively solves the problem of severe bending and deformation of the cell sheets in the existing method of preparing SOFC full cells by layer-by-layer preparation.
[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a method for preparing a solid oxide fuel cell full cell, comprising the following steps: Step 1, preparing an anode support layer slurry using a solvent S1 system, ball milling and mixing the anode support layer slurry evenly, casting it into shape, and drying it to obtain an anode support layer green body; the solvent S1 is a mixed solvent of ethanol and butanone, and the mass ratio of ethanol to butanone in solvent S1 is 1:1 or 1:3; by mass percentage, the anode support layer slurry composition includes: 35%-45% NiO, 20%-30% 8YSZ, 8%-12% graphite, 1%-2% triethyl phosphate, 5%-8% polyvinyl butyral, 4%-7% dibutyl phthalate, and the balance being solvent S1.
[0007] Step 2: Prepare the anode functional layer slurry using solvent S2 system. Grind the anode functional layer slurry evenly, cast it into shape, and dry it to obtain the anode functional layer green body. The solvent S2 is terpineol. By mass percentage, the anode functional layer slurry composition includes: 25%-35% NiO, 25%-35% 8YSZ, 1%-2% polyvinylpyrrolidone, 4%-6% ethyl cellulose, 3%-5% polyethylene glycol, and the balance is solvent S2.
[0008] Step 3: Prepare the electrolyte layer slurry using solvent S3 system. After ball milling the electrolyte layer slurry evenly, cast it into a film and dry it to obtain the electrolyte layer green body. The solvent S3 is a mixed solvent of ethanol and butanone, and the mass ratio of ethanol to butanone in solvent S3 is 1:1 or 2:1. By mass percentage, the electrolyte layer slurry composition includes: 40%-50% 8YSZ, 1.5%-2.5% polyacrylic acid, 3%-5% polyvinyl alcohol, 2%-4% polyethylene glycol, and the balance is solvent S3.
[0009] Step 4: Stack the anode support layer green blank, anode functional layer green blank, and electrolyte layer green blank in sequence, and hot press them together at a temperature of 80-120℃ and a pressure of 50-100MPa for 30-60 minutes to obtain the half-cell green blank.
[0010] Step 5: Perform a debinding process on the half-cell green body at a temperature of 300-500℃ for 1-3 hours; then sinter at 1350-1450℃ for 2-5 hours to obtain the half-cell.
[0011] Step 6: Prepare a GDC barrier layer slurry on the surface of the electrolyte layer of the half-cell. Print the GDC barrier layer slurry onto the surface of the electrolyte layer using screen printing and sinter at 1250-1350℃ for 2-4 hours. By mass percentage, the GDC barrier layer slurry consists of 50%-60% GDC powder, 3%-5% ethyl cellulose, and the balance is terpineol.
[0012] Step 7: Prepare LSCF cathode paste on the surface of GDC barrier layer. Print LSCF cathode paste on the surface of GDC barrier layer by screen printing and sinter at 1050-1150℃ for 1-3 hours to obtain solid oxide fuel cell full cell. By mass percentage, the composition of LSCF cathode paste includes: 50%-60% LSCF powder, 3%-5% ethyl cellulose, and the balance is terpineol.
[0013] Furthermore, the hot-pressing composite process adopts a stepped pressure increase method, with an initial pressure of 10-20 MPa, gradually increasing to a final pressure of 50-100 MPa, and a pressure increase rate of 5-10 MPa / min.
[0014] Furthermore, in step five, a multi-stage heating regime is adopted for debinding and sintering: First stage: room temperature to 300℃, heating rate 1-2℃ / min; Second stage: 300 to 600℃, heating rate 0.5-1℃ / min, holding for 2 hours for debinding; Third stage: 600 to 1000℃, heating rate 2-3℃ / min; Fourth stage: 1000 to 1350-1450℃, heating rate 3-5℃ / min, holding for 3 hours.
[0015] Another objective of this invention is to provide a solid oxide fuel cell full cell, prepared by the preparation method described in the above embodiments, with a curvature not exceeding 1.0%, comprising an anode support layer, an anode functional layer, an electrolyte layer, a GDC barrier layer, and an LSCF cathode layer stacked sequentially.
[0016] Furthermore, the thickness of the anode support layer is 500-800 μm, the thickness of the anode functional layer is 10-30 μm, the thickness of the electrolyte layer is 5-15 μm, the thickness of the GDC barrier layer is 3-8 μm, and the thickness of the LSCF cathode layer is 20-40 μm.
[0017] Furthermore, the curvature shall not exceed 0.3%.
[0018] Compared with the prior art, the beneficial technical effects of the present invention are: (1) The present invention optimizes the slurry formulation and solvent system of each functional layer to achieve matching of the shrinkage behavior of each layer, and the curvature of the whole cell is reduced from 2%-4% of the traditional method to below 1.0%, preferably reaching 0.3%, thereby improving the yield of the battery cell and reducing the production cost.
[0019] (2) By adopting the hot-pressing composite process, the present invention significantly improves the interfacial bonding strength between functional layers and reduces the risk of delamination; by adopting the co-sintering process, the number of sintering times is reduced, the preparation cycle is shortened, and energy consumption is reduced.
[0020] (3) The full cell prepared by the present invention has excellent electrochemical performance, with a maximum power density of more than 1.2 W / cm² at 800℃, which is superior to the battery prepared by traditional methods. Detailed Implementation
[0021] Example 1: First, some of the technical terms in this example are explained as follows: NiO represents nickel oxide; 8YSZ is 8 mol% yttrium oxide-stabilized zirconium oxide; GDC is gadolinium-doped cerium oxide; LSCF is lanthanum strontium cobalt iron oxide.
[0022] This embodiment provides a method for preparing a solid oxide fuel cell full cell, including the following steps: Step 1, preparing a green anode support layer.
[0023] Weigh 40g NiO, 25g 8YSZ, and 10g graphite powder as solid components; prepare 60g of a mixed solvent of ethanol and butanone (mass ratio 1:1) as solvent S1; add 1.5g triethyl phosphate as a dispersant, 6g polyvinyl butyral as a binder, and 5g dibutyl phthalate as a plasticizer.
[0024] The above raw materials were placed in a planetary ball mill and ball-milled for 24 hours to obtain a uniform slurry. The slurry was then degassed under vacuum and cast into a green anode support layer with a thickness of 600 μm after drying. Step 2: Prepare the green blank for the anode functional layer.
[0025] Weigh out 30g NiO and 30g 8YSZ as solid components; take 40g terpineol as solvent S2; add 1.5g polyvinylpyrrolidone as dispersant, 5g ethyl cellulose as binder, and 4g polyethylene glycol as plasticizer.
[0026] The above raw materials are ground and mixed evenly, cast into shape, and dried to obtain a green blank of an anode functional layer with a thickness of 20μm.
[0027] Step 3: Prepare the electrolyte layer green blank.
[0028] Weigh 45g of 8YSZ as the solid phase component; prepare 50g of a mixed solvent of ethanol and butanone (mass ratio 1:1) as solvent S3; add 2g of polyacrylic acid as a dispersant, 4g of polyvinyl alcohol as a binder, and 3g of polyethylene glycol as a plasticizer.
[0029] The above raw materials were ball-milled and mixed evenly, then cast and dried to obtain an electrolyte layer green body with a thickness of 10 μm.
[0030] Step 4: Lamination and bonding.
[0031] The anode support layer green blank, anode functional layer green blank, and electrolyte layer green blank are stacked in sequence and placed in a hot press. A stepped pressurization method is adopted: the initial pressure is 15 MPa, and the pressure is increased to the final pressure of 80 MPa at a rate of 8 MPa / min. The hot pressing temperature is 100℃, and the holding time is 45 minutes to obtain the half-cell green blank.
[0032] Step 5: Co-sintering.
[0033] The half-cell green was placed in a sintering furnace and subjected to a multi-stage heating regime for debinding and sintering: (1) from room temperature to 300°C at a heating rate of 1.5°C / min; (2) from 300°C to 500°C at a heating rate of 1°C / min, and held for 2 hours for debinding; (3) from 500°C to 1000°C at a heating rate of 2.5°C / min; (4) from 1000°C to 1400°C at a heating rate of 4°C / min, and held for 3 hours. The half-cell was then cooled to room temperature in the furnace to obtain the half-cell.
[0034] Step 6: Prepare the cathode functional layer.
[0035] Weigh 55g of GDC powder, add 4g of ethyl cellulose and 41g of terpineol, and grind to prepare GDC barrier layer slurry.
[0036] The GDC barrier layer paste was screen-printed onto the electrolyte layer surface of the half-cell, with a wet film thickness of 15 μm. After sintering at 1300 °C for 3 hours, a GDC barrier layer with a thickness of approximately 5 μm was obtained.
[0037] Step 7: Prepare the cathode current collector layer.
[0038] Weigh 55g of LSCF powder, add 4g of ethyl cellulose and 41g of terpineol, and grind to prepare LSCF cathode paste.
[0039] LSCF cathode paste was screen-printed onto the surface of the GDC barrier layer, with a wet film thickness of 50 μm. After sintering at 1100 °C for 2 hours, an LSCF cathode layer with a thickness of approximately 30 μm was obtained, ultimately yielding a full solid oxide fuel cell.
[0040] The solid oxide fuel cell full cell prepared in Example 1 was tested according to the relevant requirements of GB / T 20042.6-2024. The measured curvature of the SOFC full cell was 0.25%.
[0041] In Example 1, solvents S1, S2, and S3 have different compositions. By adjusting the evaporation rate of each solvent and its interaction with the binder, the shrinkage behavior of each functional layer during the drying and sintering process is controlled, thereby achieving stress matching.
[0042] Example 1: By optimizing the solvent system and slurry formulation of each functional layer, the shrinkage behavior of each layer during drying and sintering was precisely matched. The specific mechanism is as follows: (1) Differentiated design of solvent system: By designing different solvent systems for each functional layer, the rheological properties and drying shrinkage behavior of the slurry are controlled, and the internal stress caused by shrinkage mismatch is reduced. (2) Hot pressing composite process optimization: The hot pressing composite process with stepped pressure is adopted to make each functional layer fully and tightly bonded during the hot pressing process, eliminate interlayer voids, and improve the interfacial bonding strength. (3) Multi-stage sintering regime: By designing a reasonable heating program and heat preservation stage, the decomposition and discharge of organic matter and the sintering and densification process of ceramic particles are coordinated to reduce deformation during sintering. (4) Stress balance mechanism: Different slurry formulations and process parameters are used for each functional layer to match their shrinkage rates during sintering, realize stress self-balance, and thus obtain a full cell with high flatness.
[0043] Example 2: In this example, the applicant studied the effect of different solvent systems on the flatness of the full cell.
[0044] Keeping all other process conditions the same as in Example 1, only changing the solvent system for the anode support layer green body, the anode functional layer green body, and the electrolyte layer green body, the specific settings are as follows.
[0045] Experimental Group 1: S1 solvent is a mixed solvent of ethanol and butanone, with a mass ratio of ethanol to butanone of 1:3; S2 solvent is terpineol; S3 solvent is a mixed solvent of ethanol and butanone, with a mass ratio of ethanol to butanone of 2:1.
[0046] Experimental Group 2: S1 solvent is a mixed solvent of ethanol and methyl ethyl ketone, with a mass ratio of ethanol to methyl ethyl ketone of 1:1; S2 solvent is a mixed solvent of ethanol and terpineol, with a mass ratio of ethanol to terpineol of 1:1; S3 solvent is a mixed solvent of ethanol and methyl ethyl ketone, with a mass ratio of ethanol to methyl ethyl ketone of 1:1.
[0047] Experimental Group 3: S1 solvent was methyl ethyl ketone (MEK); S2 solvent was terpineol; S3 solvent was MEK.
[0048] The tortuosity, maximum power density, and interfacial bonding strength of the solid oxide fuel cell full cells prepared in Experimental Groups 1, 2, and 3 were tested according to the relevant requirements of GB / T 20042.6-2024, and the results are shown in Table 1. Table 1 shows that by using a completely differentiated solvent system (such as Experimental Group 1), the optimal cell flatness and electrochemical performance can be obtained.
[0049] Table 1. Effects of different solvent systems on full-cell performance Example 3: This example uses the same process conditions as Example 1 to prepare a large-area full cell of 110mm*125mm. The curvature, maximum power density, and cell uniformity of the large-area full cell prepared in this example were tested according to the relevant requirements of GB / T 20042.6-2024. The results show that the curvature of the large-area full cell prepared in this example is 0.32%, the maximum power density is 1.18 W / cm² (at an operating temperature of 800℃), and the performance deviation in cell uniformity is <5%.
[0050] The above results indicate that the method for preparing a solid oxide fuel cell full cell provided by this invention is applicable to the preparation of large-area SOFC full cells and has good process scalability.
[0051] Comparative Example 1: This comparative example uses a conventional casting process to prepare a solid oxide fuel cell full cell. The difference between this comparative example and Example 1 is that the anode support layer green blank, anode functional layer green blank and electrolyte layer green blank in this comparative example use the same solvent system (ethanol: methyl ethyl ketone = 1:1) and casting process parameters during preparation, without making differential adjustments to the casting conditions of each layer.
[0052] The cathode preparation process in this comparative example is the same as that in Example 1, and other steps are also consistent with those in Example 1.
[0053] The full cells prepared in this comparative example and the full cells prepared in Example 1 were subjected to flatness, electrochemical performance, interfacial bonding strength and thermal cycling tests. The results are shown in Table 2.
[0054] Table 2 Performance test results of the full cells prepared in Example 1 and Comparative Example 1 As shown in Table 2, the flatness of the full cell prepared in Example 1 is improved by 91% compared with that of Comparative Example 1. The full cell prepared in Example 1 has the advantages of high flatness, good interfacial bonding strength, excellent electrochemical performance and thermal stability compared with Comparative Example 1.
[0055] The high-flatness solid oxide fuel cell (SOFC) full cell prepared by this invention can be widely used in stationary power plants, distributed energy systems, transportation power supplies, and portable power sources. The full cell prepared using this method has advantages such as high flatness, good interfacial bonding strength, excellent electrochemical performance, and excellent thermal stability. It can significantly improve the assembly efficiency and operational stability of SOFC stacks, reduce production costs, and has broad market prospects.
[0056] Of course, the above description is not intended to limit the present invention, and the present invention is not limited to the examples given above. Any changes, modifications, additions or substitutions made by those skilled in the art within the scope of the present invention should also fall within the protection scope of the present invention.
Claims
1. A method for preparing a full cell of a solid oxide fuel cell, characterized in that, Includes the following steps: Step 1: Prepare the anode support layer slurry using solvent S1 system. After ball milling and mixing the anode support layer slurry evenly, cast it into a film and dry it to obtain the anode support layer green body. The solvent S1 is a mixed solvent of ethanol and butanone, and the mass ratio of ethanol to butanone in solvent S1 is 1:1 or 1:
3. The anode support layer slurry composition, by mass percentage, includes: 35%-45% NiO, 20%-30% 8YSZ, 8%-12% graphite, 1%-2% triethyl phosphate, 5%-8% polyvinyl butyral, 4%-7% dibutyl phthalate, and the balance being solvent S1. Step 2: Prepare the anode functional layer slurry using the S2 solvent system. Grind the anode functional layer slurry evenly, cast it into a film, and dry it to obtain the anode functional layer green body. The solvent S2 is terpineol; By mass percentage, the composition of the anode functional layer slurry includes: 25%-35% NiO, 25%-35% 8YSZ, 1%-2% polyvinylpyrrolidone, 4%-6% ethyl cellulose, 3%-5% polyethylene glycol, and the balance being solvent S2. Step 3: Prepare electrolyte layer slurry using solvent S3 system, ball mill the electrolyte layer slurry until uniform, cast into shape, and dry to obtain electrolyte layer green body; The solvent S3 is a mixed solvent of ethanol and butanone, and the mass ratio of ethanol to butanone in solvent S3 is 1:1 or 2:
1. By mass percentage, the electrolyte layer slurry composition includes: 40%-50% 8YSZ, 1.5%-2.5% polyacrylic acid, 3%-5% polyvinyl alcohol, 2%-4% polyethylene glycol, and the balance being solvent S3; Step 4: Stack the anode support layer green blank, anode functional layer green blank, and electrolyte layer green blank in sequence, and hot press them together at a temperature of 80-120℃ and a pressure of 50-100MPa for 30-60 minutes to obtain the half-cell green blank. Step 5: Perform a debinding process on the half-cell green body at a temperature of 300-500℃ for 1-3 hours; then sinter at 1350-1450℃ for 2-5 hours to obtain the half-cell. Step 6: Prepare GDC barrier layer paste on the surface of the electrolyte layer of the half cell. Print the GDC barrier layer paste on the surface of the electrolyte layer by screen printing and sinter at 1250-1350℃ for 2-4 hours. By weight percentage, the GDC barrier layer slurry consists of: 50%-60% GDC powder, 3%-5% ethyl cellulose, and the balance being terpineol. Step 7: Prepare LSCF cathode paste on the surface of GDC barrier layer. Print LSCF cathode paste on the surface of GDC barrier layer by screen printing. Sinter at 1050-1150℃ for 1-3 hours to obtain solid oxide fuel cell full cell. By weight percentage, the LSCF cathode paste consists of 50%-60% LSCF powder, 3%-5% ethyl cellulose, and the balance being terpineol.
2. The method for preparing a solid oxide fuel cell full cell according to claim 1, characterized in that, In step four, the hot-pressing composite process adopts a stepped pressure increase method, with the initial pressure being 10-20 MPa and gradually increasing to the final pressure of 50-100 MPa, and the pressure increase rate being 5-10 MPa / min.
3. The method for preparing a solid oxide fuel cell full cell according to claim 1, characterized in that, In step five, a multi-stage heating process is used for debinding and sintering: First stage: from room temperature to 300℃, heating rate 1-2℃ / min; Second stage: 300 to 600℃, heating rate 0.5-1℃ / min, hold for 2 hours and then remove the adhesive; Third stage: 600 to 1000℃, heating rate 2-3℃ / min; Fourth stage: 1000 to 1350-1450℃, heating rate 3-5℃ / min, hold for 3 hours.
4. A solid oxide fuel cell full cell, characterized in that, Prepared by the preparation method of any one of claims 1-3, with a curvature not exceeding 1.0%, comprising an anode support layer, an anode functional layer, an electrolyte layer, a GDC barrier layer, and an LSCF cathode layer stacked sequentially.
5. The solid oxide fuel cell full cell according to claim 4, characterized in that, The thickness of the anode support layer is 500-800μm, the thickness of the anode functional layer is 10-30μm, the thickness of the electrolyte layer is 5-15μm, the thickness of the GDC barrier layer is 3-8μm, and the thickness of the LSCF cathode layer is 20-40μm.
6. The solid oxide fuel cell full cell according to claim 5, characterized in that, The curvature shall not exceed 0.3%.