High-performance sintered foil matched with multi-particle-size aluminum powder for industrial production and preparation method of high-performance sintered foil

Abstract

The invention belongs to the technical field of electronic materials, and particularly relates to a high-performance sintered foil matched with multi-particle-size aluminum powder for industrial production and a preparation method of the high-performance sintered foil. In order to solve the problem that an existing sintered foil cannot obtain high bending performance and high specific capacitance performance at the same time, a multi-particle-size aluminum powder gradient matching strategy is adopted, the aluminum foil is prepared through slurry preparation, slurry stirring, double-face coating and drying integrated operation, sintering and formation treatment, the specific capacitance of the sintered foil after standardization is 0.8-1.2 mu F / cm, and the specific capacitance of the aluminum foil is 0.8-1.2 mu F / cm. The specific capacitance fluctuation range is smaller than or equal to 8%, the bending frequency is 40-100 times after a 90-degree bending test, the bent film layer is free of cracking and falling off, the leakage current is smaller than or equal to 3 [mu] A / cm < 2 > under the 25 DEG C and rated voltage test, and the film can be directly used for industrial production.

Description

Technical Field

[0001] This invention belongs to the field of electronic materials technology, specifically relating to a high-performance sintered foil with multi-size aluminum powder for industrial production and its preparation method. It is particularly suitable for the field of aluminum electrolytic capacitors, and can achieve the performance requirements of high specific capacitance, good flexibility and low leakage current, thus helping to improve the overall quality and performance of aluminum electrolytic capacitors. Background Technology

[0002] In the field of electronic components, especially in devices such as aluminum electrolytic capacitors, the anode foil, as a core electrode material, directly determines the energy storage efficiency, service life, and stability of the equipment. Traditional anode foil preparation methods often employ single-particle-size aluminum powder and conventional sintering processes. This approach faces several technical bottlenecks: First, the specific capacitance is difficult to exceed the theoretical upper limit, resulting in insufficient energy density and failing to meet the demands of emerging industries such as 5G communications and new energy vehicles for miniaturized, high-capacity energy storage devices. Second, the foil production process generates large amounts of wastewater and waste residue, containing heavy metals and chemical agents that are not only extremely harmful to the environment but also difficult and costly to treat. Direct discharge without effective treatment will pollute soil and water bodies, causing irreversible damage to the ecological environment. Third, as a subtractive manufacturing technology, foil etching presents significant cost waste, as a large amount of raw materials are not converted into effective products during production, resulting in inefficient resource utilization.

[0003] To overcome the technical challenges, research was conducted leveraging the interdisciplinary advantages of materials science and engineering, focusing on the fabrication technology of three-dimensional sintered foils. When using additive manufacturing processes to prepare sintered foils, high-purity, uniformly sized single aluminum powder was selected as the raw material. This powder was precisely coated onto the surface of the aluminum foil, and high-temperature sintering allowed the aluminum powder to accumulate layer by layer on the aluminum foil substrate, significantly improving the uniformity of the microstructure and thus producing high-quality sintered foils. However, subsequent research revealed that sintered foils prepared using single aluminum powder suffered from poor bending performance. To improve this, a pore-forming agent was added during the fabrication process, significantly enhancing the bending performance by forming a porous structure. However, the introduction of the pore-forming agent altered the internal microstructure of the material, resulting in the loss of a significant portion of aluminum powder particles. This reduced the total effective surface area of ​​the aluminum powder, leading to a substantial decrease in the specific capacitance performance of the sintered foil, making it difficult to meet the high specific capacitance standards for sintered foils in current industrial production. Summary of the Invention

[0004] To address the problem that existing sintered foils cannot simultaneously achieve high bending performance and high specific capacitance performance, this invention provides a high-performance sintered foil with multi-size aluminum powder for industrial production and its preparation method.

[0005] To achieve the above objectives, the present invention employs the following technical solution:

[0006] In a first aspect, this invention provides a high-performance sintered foil made from a mixture of aluminum powders with multiple particle sizes for industrial production. The foil is prepared by a process involving the mixing of these aluminum powders, slurry preparation, slurry stirring, double-sided coating and drying, sintering, and formation treatment. The sintered foil, after standardization, has a specific capacitance of 0.8-1.2 μF / cm², with a specific capacitance fluctuation of ≤8%. It withstands 40-100 bends after a 90° bend test, with no cracking or peeling of the film layer after bending. Under 25°C and rated voltage, the leakage current is ≤3 μA / cm². 2 .

[0007] Furthermore, the multi-particle-size aluminum powder mixing and matching is achieved by mixing any two or more aluminum powders within the particle size range of 1-2μm, 2-3μm, 3-4μm, 4-5μm, 5-6μm, 6-7μm, 7-8μm, 8-9μm, and 9-10μm.

[0008] Secondly, the present invention provides a method for preparing a high-performance sintered foil composed of multi-size aluminum powders for industrial production, comprising the following steps:

[0009] Step 1, Aluminum powder selection and blending: Select aluminum powders of different particle size ranges and mix them to obtain raw material aluminum powder;

[0010] Step 2, Preparation of slurry: Mix solvent and binder, heat and stir to form pre-solvent, then add thickener, continue heating and stirring, then add raw material aluminum powder, and stir to obtain aluminum powder slurry that meets the coating viscosity requirements;

[0011] Step 3, slurry mixing: The aluminum powder slurry obtained in Step 2 is subjected to vacuum mixing, which is divided into three stages: low-speed mixing, medium-speed mixing and high-speed mixing.

[0012] Step 4, Double-sided coating and drying integrated operation: The stirred aluminum powder slurry is simultaneously coated on both sides of the aluminum foil. The coated aluminum foil is then dried in a multi-stage gradient heating process to obtain a substrate-dry film composite.

[0013] Step 5, sintering: The substrate-dry film composite is sintered. The sintering process is divided into three stages: vacuum treatment, heating treatment, and heat preservation treatment, to obtain the sintered film layer.

[0014] Step 6, formation treatment: Perform formation treatment on the sintered film layer.

[0015] Furthermore, step 1 specifically includes:

[0016] Spherical or near-spherical aluminum powders with particle sizes in the ranges of 1-2μm, 2-3μm, 3-4μm, 4-5μm, 5-6μm, 6-7μm, 7-8μm, 8-9μm, and 9-10μm are selected, and any two or more aluminum powders in the above ranges are mixed together.

[0017] The above-mentioned selection and mixing of spherical or near-spherical aluminum powders with different particle size ranges offers significant advantages. Firstly, the multi-particle size combination allows for a tighter packing of the aluminum powder particles. Larger particles form the framework, while smaller particles fill the space, creating a rich and well-structured pore structure. This facilitates electrolyte penetration and ion transport, significantly improving the specific capacitance of the sintered foil to 0.85-1.2 μF / cm² and reducing specific capacitance fluctuations. Secondly, the spherical or near-spherical shape reduces stress concentration points, and the multi-particle size combination disperses stress through the pores during bending, enhancing the flexibility of the sintered foil. This allows it to withstand 40-100 bends in a 90° bend test, with the film layer less prone to cracking and peeling, effectively improving the product's mechanical properties.

[0018] Furthermore, step 2 specifically includes:

[0019] The solvent and binder are mixed at a mass ratio of 95-97:3-5 and heated and stirred at 70-100℃ to form a pre-solvent. Then, a thickener is added at a mass ratio of 0.5-5:100 to the pre-solvent, and the mixture is heated and stirred at 60-90℃ to form a thickening solvent. Subsequently, aluminum powder is added at this temperature at a mass ratio of 1-7:3-9 to the thickening solvent.

[0020] Furthermore, the solvent is terpineol, the binder is ethyl cellulose, and the thickener is PEG6000.

[0021] Furthermore, the solvent may also be combined with any one or more of methanol, ethanol, isopropanol, n-butanol, and isoamyl alcohol; the binder may also be combined with any one or more of polyvinylidene fluoride, polyvinyl alcohol, sodium carboxymethyl cellulose, styrene-butadiene rubber, and polyvinyl acetate; and the thickener may also be combined with any one or more of hydroxypropyl methylcellulose, xanthan gum, fumed silica, guar gum, and gum arabic.

[0022] The above-mentioned slurry preparation process has significant advantages. A pre-solvent is prepared by mixing solvent and binder in a specific ratio and stirring at high temperature. A thickener is then added to prepare a thickening solvent, and finally, aluminum powder is added. Precise control of temperature and material ratios at each stage ensures thorough mixing of all components, guaranteeing the slurry's dispersibility and stability. Based on terpineol, ethyl cellulose, and PEG6000, the slurry exhibits good compatibility and can be flexibly combined with other solvents, binders, and thickeners to meet diverse performance requirements. This provides a high-quality slurry for subsequent coating, drying, and sintering processes, facilitating the production of high-performance sintered foils.

[0023] Furthermore, step 3 specifically includes:

[0024] The aluminum powder slurry obtained in step 2 was subjected to vacuum stirring, with the vacuum level set to -0.08MPa to -0.095MPa. The vacuum environment was used to defoam the aluminum powder slurry. The stirring speed was divided into three stages: low speed stage with a speed of 500-800 r / min and a stirring time of 0.5-1 h; medium speed stage with a speed of 1200-1800 r / min and a stirring time of 1-2 h; and high speed stage with a speed of 2000-5000 r / min and a stirring time of 0.5-1.5 h. Through vacuum defoaming, the viscosity of the aluminum powder slurry was ensured to be stable within the range of 2000-8000 mPa·s.

[0025] The aforementioned three-stage mixing is an optimized design that combines the characteristics of aluminum powder with industrial requirements. The low-speed stage provides gentle premixing, preventing aluminum powder agglomeration or stratification and laying the foundation for dispersion; the medium-speed stage breaks up weak agglomerates and protects particle morphology, while also aiding in vacuum defoaming; the high-speed stage breaks up stubborn agglomerates and controls slurry viscosity. It is compatible with aluminum powders of various particle sizes, ensuring consistent sintered foil performance, reducing mass production fluctuations, and, in conjunction with vacuum defoaming, improving slurry coatability and helping to produce compliant products.

[0026] Furthermore, step 4 specifically involves:

[0027] The stirred aluminum powder slurry is simultaneously coated onto both sides of the aluminum foil at a speed of 1.5-30 m / min, with the wet film thickness controlled at 45-65 μm. The coated aluminum foil is then subjected to multi-stage gradient heating and drying: the first stage is drying at 60-80℃ for 5-30 seconds to remove 60%-70% of the low-boiling-point solvents; the second stage is heating to 90-110℃ and drying for 10-120 seconds to remove the remaining medium-boiling-point solvents; the third stage and / or subsequent stages are drying at 90-110℃ to completely remove the trace amounts of residual solvents in the binder and thickener, finally obtaining a substrate-dry film composite with a dry film moisture content ≤0.5%.

[0028] The above-mentioned process has significant advantages in the coating and drying stages. Simultaneous double-sided coating at speeds of 1.5-30 m / min meets the efficiency requirements of industrial mass production, and the 45-65 μm wet film thickness is precisely controllable, laying the foundation for consistent subsequent performance. The multi-stage gradient heating and drying process is ingenious: 60%-70% of the low-boiling-point solvent is removed at 60-80℃, and medium-boiling-point solvent and residual trace solvent are removed at 90-110℃. This avoids sudden temperature changes that could cause film cracking and blistering, while ensuring complete solvent removal. The final product is a substrate-dry film composite with a moisture content ≤0.5%, providing a solid foundation for subsequent sintering and achieving the required specific capacitance, bending performance, and low leakage current of the sintered foil.

[0029] Furthermore, step 5 specifically includes:

[0030] The substrate-dry film composite is sintered in three stages: vacuuming / argon treatment, heating, and holding. The sintering time needs to be adjusted according to the quality of the sintered foil in the sintering furnace. In the first stage, vacuuming / introducing argon gas with a purity ≥99.999% is performed, and the temperature is raised to 200-300℃ at a rate of 5-20℃ / min, and held for 1-5 hours. In the second stage, air, argon gas with a purity ≥99.999%, or a vacuum is maintained, and the temperature is raised to 400-500℃ at a rate of 5-20℃ / min, and held for 2-10 hours. In the third stage, argon gas with a purity ≥99.999% is introduced, and the temperature is raised to 630-650℃ at a rate of 5-20℃ / min, and held for 2-12 hours. After the third stage, the temperature is lowered at a rate of 5-20℃ / min to finally obtain the sintered film layer.

[0031] The three-stage sintering process described above is a scientifically designed approach adapted to the characteristics of the substrate-dry film composite. The first stage involves vacuuming / purifying with high-purity argon and heating to 200-300℃ for holding, which gently removes residual solvents and low-molecular-weight impurities, preventing carbonization of impurities at high temperatures from affecting the film layer. The second stage flexibly selects the atmosphere to heat to 400-500℃ for holding, gradually decomposing the binder and thickener, reducing film cracking caused by violent gas release. The third stage involves purging with high-purity argon and heating to 630-650℃ for holding. Argon, as an inert gas, effectively isolates the film from air, preventing aluminum powder oxidation at high temperatures, thereby promoting metallurgical bonding of aluminum powder particles and forming a stable pore structure. The consistent temperature control and cooling rates in each stage ensure uniform stress in the film layer, laying the foundation for the excellent performance of the sintered foil.

[0032] Compared with the prior art, the present invention has the following advantages:

[0033] This invention employs a multi-particle-size aluminum powder gradient combination strategy. Through precise proportioning and orderly arrangement of aluminum powders of different particle sizes, a clever microstructure is constructed during the sintering process. This technological breakthrough achieves synergistic control of the porosity and density of the material's microstructure without the need for traditional pore-forming agents. Compared to sintered foils prepared from single-particle-size aluminum powders in traditional processes, this method completely resolves the two major technical contradictions of "poor flexibility" and "capacity reduction due to the addition of pore-forming agents." Thanks to its unique microstructure design, the prepared sintered foil possesses both excellent flexibility and high energy storage characteristics, effectively resisting external pressure and deformation, fully meeting the stringent standards of aluminum electrolytic capacitors in terms of both high energy storage requirements and deformation resistance.

[0034] By scientifically combining aluminum powders of various particle sizes, a unique porous structure is formed within the sintered foil. This unique pore distribution, through the construction of a three-dimensional network of stress transmission paths, effectively disperses stress concentration during bending. During plastic deformation, the micron-sized pores act as flexible buffer units, promptly absorbing and dissipating stress energy, preventing local stress peaks from exceeding the material's yield strength. Simultaneously, the gradient-distributed pore structure allows stress to gradually decrease at the interfaces formed by aluminum powders of different particle sizes, significantly improving the crack resistance of the sintered foil under complex forming processes. Compared to traditional foils, the sintered foil of this invention exhibits over 30% improved bending performance, is less prone to cracking or breakage, significantly enhances the product's applicability in complex processing scenarios, and reduces the scrap rate due to insufficient material toughness.

[0035] Compared to existing sintered foil preparation processes that require 5-7 additives and auxiliary materials, this invention uses only basic aluminum powder and 2 necessary additives, reducing the types of raw materials by over 60%. By optimizing the mixing ratio and process parameters, the use of expensive special additives is avoided, resulting in a direct reduction of raw material costs by over 40%. At the same time, the streamlined raw material system reduces complex pre- and post-processing procedures, further reducing energy consumption and equipment wear and tear, and lowering the overall production cost by 35%-40% compared to traditional processes.

[0036] In existing processes, the use of pore-forming agents (such as ammonium bicarbonate and polymethyl methacrylate) generates a large amount of volatile organic compounds (VOCs) and harmful gases (such as ammonia) during the sintering stage, requiring additional investment in exhaust gas treatment equipment; moreover, residual pore-forming agents easily lead to an increased waste rate (approximately 8%-12%). This invention eliminates the need for pore-forming agents, forming pores solely through the particle size distribution of aluminum powder, reducing VOC emissions by 100% and eliminating the generation of harmful gases. Simultaneously, the streamlined raw material system reduces slurry waste caused by "additive incompatibility," lowering the waste rate to below 3%, thus reducing environmental treatment costs and aligning with the trend of green manufacturing.

[0037] Existing sintered foils, due to their simple microstructure, struggle to simultaneously meet the dual requirements of "high specific capacitance" and "low equivalent series resistance (ESR)". The multi-level porous structure of this invention allows for performance customization by adjusting the aluminum powder particle size distribution: for high specific capacitance, the proportion of 1-5 μm aluminum powder can be increased to improve specific surface area; for low ESR, the proportion of 6-10 μm aluminum powder can be increased to optimize the electrolyte ion transport channels. Based on this, the prepared sintered foil can be adapted to different types of aluminum electrolytic capacitors—in the consumer electronics field, the high specific capacitance meets miniaturization requirements; in the new energy field, the low ESR characteristic adapts to high-frequency charging and discharging scenarios, expanding the product's high-value-added application space. Attached Figure Description

[0038] Figure 1 This is a schematic diagram of the microstructure of multi-particle-size aluminum powder mixture of the present invention (1-2μm fine powder fills the gaps between 9-10μm coarse powder to form a gradient porous structure).

[0039] Figure 2 This is a process flow diagram of the preparation method of the present invention;

[0040] Figure 3 This is a scanning electron microscope (SEM) image of the anode foil prepared using multi-size aluminum powder according to the present invention. As can be seen from the image, the multi-size aluminum powder forms a rich and rationally distributed pore structure. Regarding bending performance, these pores effectively disperse the stress generated during bending, preventing stress concentration that could lead to film cracking and detachment. This allows the sintered foil to withstand 40-100 bends at 90° without losing film integrity. In terms of specific capacitance, the diverse pores increase the effective surface area of ​​the aluminum powder, providing more sites for charge storage. Simultaneously, the pore structure facilitates electrolyte penetration and ion transport, helping the sintered foil achieve a specific capacitance of 0.85-1.2 μF / cm² under standard testing, while ensuring a specific capacitance fluctuation of ≤8%. Detailed Implementation

[0041] To further illustrate the technical solution of the present invention, the present invention will be further described below through embodiments.

[0042] Example 1

[0043] This embodiment describes a method for preparing high-performance sintered foil using multi-size aluminum powder for industrial production. Figure 2 ), including the following steps:

[0044] S1. Select spherical aluminum powder with a particle size of 1-2μm (1%) and 9-10μm (99%). Figure 1 The mass ratio of the two was set to 1:99, and they were mixed to obtain raw aluminum powder.

[0045] S2. Solvent terpineol and binder ethyl cellulose are mixed at a mass ratio of 97:3 and stirred at 70°C for 30 minutes to form a presolvent. Thickener PEG6000 is mixed with the presolvent at a mass ratio of 0.5:100 and heated and stirred at 60°C for 20 minutes to prepare a thickening solvent. Subsequently, aluminum powder is added at this temperature, with the mass ratio of thickening solvent to aluminum powder controlled at 4:6, to obtain an aluminum powder slurry.

[0046] S3. Place the aluminum powder slurry obtained in S2 into a vacuum double planetary mixer, set the vacuum degree to be maintained at -0.08MPa, and divide the stirring speed into three stages: stirring at low speed of 500r / min for 0.5 hours, medium speed of 1200r / min for 1 hour, and high speed of 2000r / min for 0.5 hours in sequence, and finally obtain an aluminum powder slurry with a viscosity of 2000mPa・s.

[0047] S4. Using a micro-gravure coating machine or a comma-shaped doctor blade coating machine (integrated with an online drying oven), double-sided aluminum powder slurry coating and drying are performed on high-purity aluminum foil with a thickness of approximately 30μm and a purity ≥99.99%. The uniformly stirred aluminum powder slurry is simultaneously coated on both sides of the aluminum foil at a coating speed of 1.5m / min, forming a 45μm wet film. The thickness is monitored in real time using an online thickness gauge to ensure the thickness deviation is within ±2μm. The coated aluminum foil then enters a multi-stage gradient heating hot air circulating drying oven: the first stage is drying at 60℃ for 5 seconds, the second stage is heating to 90℃ and drying for 10 seconds, and the third stage is drying at 90℃ for 15 seconds, obtaining a substrate-dry film composite with a dry film moisture content reduced to 0.4%.

[0048] S5. The substrate-dry film composite is placed in a bell-type sintering furnace. The sintering process is divided into three stages: vacuum treatment, heating treatment, and heat preservation treatment. In the first stage, vacuum treatment is performed, and the temperature is raised to 200°C at a heating rate of 5°C / min and held for 1 hour. In the second stage, the temperature is raised to 400°C at a rate of 5°C / min and held for 2 hours in a vacuum environment. In the third stage, argon gas with a purity of ≥99.999% is introduced, and the temperature is raised to 630°C at a rate of 5°C / min and held for 2 hours. Finally, the temperature is lowered at a rate of 5°C / min to obtain the sintered film layer.

[0049] S6. After sintering, the sintered film is subjected to formation treatment at 25℃ and 520Vf. The resulting product has a specific capacitance of 0.85μF / cm² with a fluctuation range of 8%, can withstand 40 bends, and the film does not crack or fall off after bending. The leakage current is 3μA / cm².

[0050] Example 2

[0051] This embodiment describes a method for preparing a high-performance sintered foil using multi-size aluminum powder for industrial production, comprising the following steps:

[0052] S1. Select spherical aluminum powder with a particle size of 3-4μm (90%) and 1-2μm (10%), mix them at a mass ratio of 9:1, and then mix and match them to obtain raw material aluminum powder.

[0053] S2. The solvent is a mixture of terpineol and ethanol at a mass ratio of 1:1. The binder is a mixture of ethyl cellulose and polyvinylidene fluoride at a mass ratio of 1:1. These two mixtures are then combined at a mass ratio of 95:5 and stirred at 100°C for 40 minutes to form a pre-solvent. The thickener is a mixture of PEG6000 and the pre-solvent at a mass ratio of 1.5:100, which is then heated and stirred at 90°C for another 30 minutes to prepare a thickening solvent. Subsequently, aluminum powder is added at this temperature, with a mass ratio of thickening solvent to aluminum powder of 3:7, to obtain an aluminum powder slurry.

[0054] S3. Place the aluminum powder slurry obtained in S2 into a vacuum double planetary mixer, set the vacuum degree to be maintained at -0.095MPa, and divide the stirring speed into three stages: low speed 800r / min for 1 hour, medium speed 1800r / min for 2 hours, and high speed 5000r / min for 1.5 hours. The final viscosity of the aluminum powder slurry reaches 8000mPa・s.

[0055] S4. Using a micro-gravure coating machine or a comma-shaped doctor blade coating machine (integrated with an online drying oven), double-sided aluminum powder slurry coating and drying are performed on high-purity aluminum foil with a thickness of approximately 30μm and a purity ≥99.99%. The uniformly stirred aluminum powder slurry is simultaneously coated on both sides of the aluminum foil at a coating speed of 30m / min, resulting in a wet film thickness of 65μm. The thickness is monitored in real-time using an online thickness gauge to ensure the thickness deviation is within ±2μm. The coated aluminum foil then enters a multi-stage gradient heating hot air circulating drying oven: the first stage is drying at 80℃ for 30 seconds, the second stage is heating to 110℃ and drying for 120 seconds, and the third stage is drying at 110℃ for 30 seconds, obtaining a substrate-dry film composite with a dry film moisture content of 0.3%.

[0056] S5. The substrate-dry film composite is placed in a bell-type sintering furnace. The sintering process is carried out in three stages: vacuum treatment, heating treatment, and heat preservation treatment. In the first stage, vacuum treatment is carried out, and the temperature is raised to 300℃ at a rate of 20℃ / min and held for 5 hours. In the second and third stages, under argon atmosphere, the temperature is raised to 500℃ at a rate of 20℃ / min and held for 10 hours, and raised to 650℃ and held for 12 hours, respectively. Finally, the temperature is lowered at a rate of 20℃ / min to obtain the sintered film layer.

[0057] S6. After sintering, the sintered film layer is subjected to formation treatment at 25℃ and 520Vf voltage. The specific capacitance of the product reaches 1.2μF / cm² with a fluctuation of 5%. It can be bent 100 times, and the film layer does not crack or fall off after bending. The leakage current is only 1μA / cm².

[0058] Example 3

[0059] This embodiment describes a method for preparing a high-performance sintered foil using multi-size aluminum powder for industrial production, comprising the following steps:

[0060] S1. Use spherical aluminum powder with a particle size of 2-3μm (70%) and 8-9μm (30%) in a mass ratio of 7:3, and mix them to obtain raw material aluminum powder.

[0061] S2. The solvent is a mixture of terpineol and isopropanol at a mass ratio of 2:1. The binder is a mixture of ethyl cellulose and polyvinyl alcohol at a mass ratio of 2:1. The two are then mixed at a mass ratio of 96:4 and stirred at 80°C for 35 minutes to form a pre-solvent. The thickener is a mixture of PEG6000 and xanthan gum at a mass ratio of 2:1, which is then mixed with the pre-solvent at a mass ratio of 0.5:100 and stirred at 70°C for 25 minutes to prepare a thickening solvent. Subsequently, aluminum powder is added at this temperature, with the ratio of thickening solvent to aluminum powder being 1:9, to obtain an aluminum powder slurry.

[0062] S3. Place the aluminum powder slurry obtained in S2 into a vacuum double planetary mixer, set the vacuum degree to be maintained at -0.085MPa, and divide the stirring speed into three stages: low speed 600r / min for 0.6 hours, medium speed 1300r / min for 1.2 hours, and high speed 2500r / min for 0.6 hours to obtain an aluminum powder slurry with a viscosity of 3000mPa・s.

[0063] S4. Using a micro-gravure coating machine or a comma-shaped doctor blade coating machine (integrated with an online drying oven), double-sided aluminum powder slurry coating and drying are performed on high-purity aluminum foil with a thickness of approximately 30μm and a purity ≥99.99%. The uniformly stirred aluminum powder slurry is simultaneously coated on both sides of the aluminum foil at a coating speed of 5m / min, resulting in a wet film thickness of 48μm. The thickness is monitored in real-time using an online thickness gauge to ensure the thickness deviation is within ±2μm. The coated aluminum foil then enters a multi-stage gradient heating hot air circulating drying oven: dried at 65℃ for 10 seconds, 95℃ for 20 seconds, and 95℃ for 18 seconds, to obtain a substrate-dry film composite with a dry film moisture content of 0.45%.

[0064] S5. The dried substrate-dry film composite is placed in a bell-type sintering furnace. The sintering process is carried out in three stages: vacuum treatment, heating treatment, and heat preservation treatment. First, the temperature is raised to 220°C at a rate of 5°C / min and held for 2 hours. Then, the temperature is raised to 420°C at a rate of 5°C / min and held for 3 hours in an air environment. Then, argon gas is introduced and the temperature is raised to 635°C at a rate of 5°C / min and held for 4 hours. Finally, the temperature is lowered at a rate of 5°C / min to obtain the sintered film layer.

[0065] S6. After sintering, the sintered film is subjected to formation treatment at 25℃ and 520Vf. The specific capacitance of the product is 0.87μF / cm², with a fluctuation of 7.5%. It can be bent 45 times without cracking or peeling after bending, and the leakage current is 2.8μA / cm².

[0066] Example 4

[0067] S1. Select spherical aluminum powder with a particle size of 8-9μm (80%) and 2-3μm (20%), in a mass ratio of 4:1, and mix them to obtain raw material aluminum powder.

[0068] S2. The solvent is a mixture of terpineol and n-butanol in a mass ratio of 1:2. The binder is a mixture of ethyl cellulose and sodium carboxymethyl cellulose in a mass ratio of 3:1. The two are mixed at a mass ratio of 96:4 and stirred at 90°C for 38 minutes to form a pre-solvent. The thickener is a mixture of PEG6000 and fumed silica in a mass ratio of 3:1, which is then mixed with the pre-solvent at a mass ratio of 1.5:100 and stirred at 85°C for 28 minutes to prepare a thickening solvent. Subsequently, aluminum powder is added at this temperature, with the mass ratio of thickening solvent to aluminum powder being 5:5, to obtain an aluminum powder slurry.

[0069] S3. Place the aluminum powder slurry obtained in S2 into a vacuum double planetary mixer, maintain the vacuum degree at -0.09MPa, and stir at low speed of 700r / min for 0.8 hours, medium speed of 1600r / min for 1.8 hours, and high speed of 4000r / min for 1.2 hours until the viscosity of the aluminum powder slurry reaches 7000mPa・s.

[0070] S4. Using a micro-gravure coating machine or a comma-shaped doctor blade coating machine (integrated with an online drying oven), double-sided aluminum powder slurry coating and drying are performed on high-purity aluminum foil with a thickness of approximately 30μm and a purity ≥99.99%. The uniformly stirred aluminum powder slurry is simultaneously coated on both sides of the aluminum foil at a coating speed of 25m / min, with a wet film thickness of 62μm. The coated aluminum foil is then immediately placed in a multi-stage gradient heating hot air circulation drying oven: dried at 75℃ for 25 seconds, 105℃ for 100 seconds, and 105℃ for 28 seconds to obtain a substrate-dry film composite with a dry film moisture content of 0.35%.

[0071] S5. The dried substrate-dry film composite is placed in a bell-type sintering furnace. The sintering process is carried out in three stages: vacuum treatment, heating treatment, and heat preservation treatment. First, the temperature is raised to 290℃ at a rate of 20℃ / min and held for 4.5 hours. Then, under argon atmosphere, the temperature is raised to 490℃ at a rate of 20℃ / min and held for 9 hours, and then raised to 648℃ and held for 11 hours. Finally, the temperature is lowered at a rate of 20℃ / min to obtain the sintered film layer.

[0072] S6. After sintering, the product undergoes formation treatment at 25℃ and 520Vf. The specific capacitance is 1.15μF / cm² with a fluctuation of 6%. It can be bent 90 times without cracking or peeling of the film layer after bending, and the leakage current is 1.2μA / cm².

[0073] Example 5

[0074] This embodiment describes a method for preparing a high-performance sintered foil using multi-size aluminum powder for industrial production, comprising the following steps:

[0075] S1. Spherical aluminum powders with particle sizes of 1-2μm (10%), 5-6μm (60%), and 9-10μm (30%) are mixed in a mass ratio of 1:6:3 to obtain raw aluminum powder.

[0076] S2. The solvent is a mixture of terpineol and isoamyl alcohol in a 3:1 mass ratio. The binder is a mixture of ethyl cellulose and styrene-butadiene rubber in a 1:1 mass ratio. The two are mixed in a 97:3 ratio and stirred at 75°C for 30 minutes to form a pre-solvent. The thickener is a mixture of PEG6000 and gum arabic in a 2:1 mass ratio, mixed with the pre-solvent in a 5:100 ratio, and stirred at 65°C for 20 minutes to form a thickening solvent. Subsequently, aluminum powder is added at this temperature, with the mass ratio of thickening solvent to aluminum powder being 7:3, to obtain an aluminum powder slurry.

[0077] S3. Place the aluminum powder slurry obtained in S2 into a vacuum double planetary mixer, set the vacuum degree to control at -0.082MPa, and the stirring sequence is: low speed 550r / min for 0.6 hours, medium speed 1300r / min for 1.2 hours, and high speed 2800r / min for 0.7 hours. The viscosity of the aluminum powder slurry is 3500mPa・s.

[0078] S4. Using a micro-gravure coating machine or a comma-shaped doctor blade coating machine (integrated with an online drying oven), double-sided aluminum powder slurry coating and drying are performed on high-purity aluminum foil with a thickness of approximately 30μm and a purity ≥99.99%. The uniformly stirred aluminum powder slurry is simultaneously coated on both sides of the aluminum foil at a coating speed of 8m / min, with a wet film thickness of 45μm. The coated aluminum foil is then immediately placed in a multi-stage gradient heating hot air circulating drying oven: dried by baking at 68℃ for 15 seconds, 98℃ for 40 seconds, and 98℃ for 19 seconds, to obtain a substrate-dry film composite with a dry film moisture content of 0.4%.

[0079] S5. The dried substrate-dry film composite is placed in a bell-type sintering furnace. The sintering process is carried out in three stages: vacuum treatment, heating treatment, and heat preservation treatment. First, the temperature is raised to 220°C at a rate of 8°C / min and held for 2.5 hours. Then, the temperature is raised to 430°C at a rate of 8°C / min and held for 4 hours in an air environment. Then, argon gas is introduced and the temperature is raised to 635°C at a rate of 8°C / min and held for 5 hours. Finally, the temperature is lowered at a rate of 8°C / min to obtain the sintered film layer.

[0080] S6. After sintering, the product undergoes formation treatment at 25℃ and 520Vf. The specific capacitance is 0.92μF / cm² with a fluctuation of 8%. It can be bent 55 times without cracking or peeling of the film layer after bending, and the leakage current is 2.4μA / cm².

[0081] Example 6

[0082] This embodiment describes a method for preparing a high-performance sintered foil using multi-size aluminum powder for industrial production, comprising the following steps:

[0083] S1. Select spherical aluminum powder with particle sizes of 3-4μm (20%), 6-7μm (50%), and 9-10μm (30%), in a mass ratio of 2:5:3, and mix them to obtain raw material aluminum powder.

[0084] S2. The solvent is a 1:1 mixture of terpineol and methanol. The binder is a 1:2 mixture of ethyl cellulose and polyvinyl acetate. These two are mixed at a 95:5 mass ratio and stirred at 95°C for 35 minutes to form a pre-solvent. The thickener is a 1:1 mixture of PEG6000 and guar gum, mixed with the pre-solvent at a 1.3:100 mass ratio and stirred at 85°C for 27 minutes to prepare the thickening solvent. Then, at this temperature, aluminum powder is added, with a 5:5 mass ratio of thickening solvent to aluminum powder, to obtain an aluminum powder slurry.

[0085] S3. Place the aluminum powder slurry obtained in S2 into a vacuum double planetary mixer, set the vacuum degree to maintain at -0.093MPa, and stir at low speed of 720r / min for 0.8 hours, medium speed of 1600r / min for 1.6 hours, and high speed of 3800r / min for 1.1 hours. The final viscosity of the aluminum powder slurry reaches 6500mPa・s.

[0086] S4. Using a micro-gravure coating machine or a comma-shaped doctor blade coating machine (integrated with an online drying oven), double-sided aluminum powder slurry coating and drying are performed on high-purity aluminum foil with a thickness of approximately 30μm and a purity ≥99.99%. The uniformly stirred aluminum powder slurry is coated at a speed of 22m / min, resulting in a wet film thickness of 65μm. The coated aluminum foil is then immediately placed in a multi-stage gradient heating hot air circulating drying oven: dried by baking at 75℃ for 22 seconds, 105℃ for 90 seconds, and 105℃ for 25 seconds, resulting in a substrate-dry film composite with a dry film moisture content of 0.38%.

[0087] S5. The dried substrate-dry film composite is placed in a bell-type sintering furnace. The sintering process is carried out in three stages: vacuum treatment, heating treatment, and heat preservation treatment. First, the temperature is raised to 270°C at a rate of 18°C / min and held for 1 hour. Then, in an air environment, the temperature is raised to 470°C at a rate of 18°C / min and held for 2 hours. Then, argon gas is introduced and the temperature is raised to 645°C at a rate of 18°C / min and held for 2 hours. Finally, the temperature is lowered at a rate of 18°C / min to obtain the sintered film layer.

[0088] S6. After sintering, the product undergoes formation treatment at 25℃ and 520Vf. The specific capacitance reaches 1.05μF / cm² with a fluctuation of 6%. It can be bent 75 times without cracking or peeling of the film layer after bending, and the leakage current is 1.8μA / cm².

[0089] Example 7

[0090] This embodiment describes a method for preparing a high-performance sintered foil using multi-size aluminum powder for industrial production, comprising the following steps:

[0091] S1. Take spherical aluminum powder with a particle size of 1-2μm (30%) and 4-5μm (70%), mix them at a mass ratio of 3:7 to obtain raw aluminum powder.

[0092] S2. The solvent used is pure terpineol. The binder is a mixture of ethyl cellulose and polyvinyl alcohol in a 1:1 mass ratio, which is then mixed at a mass ratio of 96:4 and stirred at 80°C for 32 minutes to form a pre-solvent. The thickener is a mixture of PEG6000 and hydroxypropyl methylcellulose in a 2:1 mass ratio, which is then mixed with the pre-solvent at a mass ratio of 0.9:100 and stirred at 70°C for 20 minutes to prepare a thickening solvent. Subsequently, aluminum powder is added at this temperature, with a mass ratio of thickening solvent to aluminum powder of 2:8, to obtain an aluminum powder slurry.

[0093] S3. Place the aluminum powder slurry obtained in step 2 into a vacuum double planetary mixer, set the vacuum degree to control at -0.088MPa, and the stirring sequence is: low speed 600r / min for 0.7 hours, medium speed 1400r / min for 1.4 hours, and high speed 3200r / min for 0.9 hours. The viscosity of the aluminum powder slurry is 4500mPa・s.

[0094] S4. Using a micro-gravure coating machine or a comma-shaped doctor blade coating machine (integrated with an online drying oven), double-sided aluminum powder slurry coating and drying are performed on high-purity aluminum foil with a thickness of approximately 30μm and a purity ≥99.99%. The uniformly stirred aluminum powder slurry is simultaneously coated on both sides of the aluminum foil at a coating speed of 5m / min, with a wet film thickness of 48μm. The coated aluminum foil is then immediately placed in a multi-stage gradient heating hot air circulating drying oven: dried by baking at 60℃ for 8 seconds, 92℃ for 20 seconds, and 92℃ for 16 seconds, with a dry film moisture content of 0.42%.

[0095] S5. The dried substrate-dry film composite is placed in a bell-type sintering furnace. The sintering process is carried out in three stages: vacuum treatment, heating treatment, and heat preservation treatment. First, the temperature is raised to 240℃ at a rate of 10℃ / min and held for 3 hours. Then, under argon atmosphere, the temperature is raised to 440℃ at a rate of 10℃ / min and held for 5 hours, and then raised to 638℃ and held for 6 hours. Finally, the temperature is lowered at a rate of 10℃ / min to obtain the sintered film layer.

[0096] S6. After sintering, the product undergoes formation treatment at 25℃ and 520Vf. The specific capacitance is 0.89μF / cm² with a fluctuation of 7%. It can be bent 48 times without cracking or peeling of the film layer after bending, and the leakage current is 2.6μA / cm².

[0097] Example 8

[0098] This embodiment describes a method for preparing a high-performance sintered foil using multi-size aluminum powder for industrial production, comprising the following steps:

[0099] S1. Select spherical aluminum powder with a particle size of 6-7μm (70%) and 2-3μm (30%), in a mass ratio of 7:3, and mix them to obtain raw material aluminum powder.

[0100] S2. The solvent is a mixture of terpineol and ethanol in a mass ratio of 1:2. The binder is a mixture of ethyl cellulose and polyvinylidene fluoride in a mass ratio of 3:1. The two are mixed at a mass ratio of 95:5 and stirred at 100°C for 40 minutes to form a pre-solvent. The thickener is a mixture of PEG6000 and xanthan gum in a mass ratio of 1:2, which is then mixed with the pre-solvent at a mass ratio of 1.5:100 and stirred at 90°C for 30 minutes to form a thickening solvent. Subsequently, aluminum powder is added at this temperature, with the mass ratio of thickening solvent to aluminum powder being 4:6, to obtain an aluminum powder slurry.

[0101] S3. Place the aluminum powder slurry obtained in S2 into a vacuum double planetary mixer, set the vacuum degree to be maintained at -0.095MPa, and stir at low speed of 800r / min for 1 hour, medium speed of 1800r / min for 2 hours, and high speed of 5000r / min for 1.5 hours until the viscosity of the aluminum powder slurry reaches 8000mPa・s.

[0102] S4. Using a micro-gravure coating machine or a comma-shaped doctor blade coating machine (integrated with an online drying oven), double-sided aluminum powder slurry coating and drying are performed on high-purity aluminum foil with a thickness of approximately 30μm and a purity ≥99.99%. The uniformly stirred aluminum powder slurry is simultaneously coated on both sides of the aluminum foil at a coating speed of 30m / min, with a wet film thickness of 65μm. The coated aluminum foil is then immediately placed in a multi-stage gradient heating hot air circulating drying oven: dried by baking at 80℃ for 30 seconds, 110℃ for 120 seconds, and 110℃ for 30 seconds to obtain a substrate-dry film composite with a dry film moisture content of 0.3%.

[0103] S5. The dried substrate-dry film composite is placed in a bell-type sintering furnace. The sintering process is carried out in three stages: vacuum treatment, heating treatment, and heat preservation treatment. First, the temperature is raised to 300℃ at a rate of 15℃ / min and held for 5 hours. Then, under vacuum, the temperature is raised to 500℃ at a rate of 15℃ / min and held for 10 hours. Then, argon gas is introduced and the temperature is raised to 650℃ at a rate of 15℃ / min and held for 12 hours. Finally, the temperature is lowered at a rate of 15℃ / min to obtain the sintered film layer.

[0104] S6. After sintering, the product undergoes formation treatment at 25℃ and 520Vf. The specific capacitance is 1.2μF / cm² with a fluctuation of 5%. It can be bent 100 times without cracking or peeling of the film layer after bending, and the leakage current is 1μA / cm².

[0105] Example 9

[0106] This embodiment describes a method for preparing a high-performance sintered foil using multi-size aluminum powder for industrial production, comprising the following steps:

[0107] S1. Mix spherical aluminum powder with a particle size of 3-4μm (45%) and 9-10μm (55%) at a mass ratio of 9:11 to obtain raw aluminum powder.

[0108] S2. The solvent is a 1:1 mixture of terpineol and isopropanol. The binder is a 2:1 mixture of ethyl cellulose and sodium carboxymethyl cellulose. These two are mixed at a 96:4 mass ratio and stirred at 95°C for 35 minutes to form a pre-solvent. The thickener is a 1:1 mixture of PEG6000 and fumed silica, mixed with the pre-solvent at a 1.1:100 mass ratio and stirred at 85°C for 25 minutes to prepare a thickening solvent. Then, at this temperature, aluminum powder is added, with a thickening solvent to aluminum powder mass ratio of 3:7, to obtain an aluminum powder slurry.

[0109] S3. Place the aluminum powder slurry obtained in step 2 into a vacuum double planetary mixer, set the vacuum degree to control at -0.092MPa, and the stirring sequence is: low speed 500r / min for 0.9 hours, medium speed 1700r / min for 1.8 hours, and high speed 4200r / min for 1.3 hours. The viscosity of the aluminum powder slurry is 7000mPa・s.

[0110] S4. Using a micro-gravure coating machine or a comma-shaped doctor blade coating machine (integrated with an online drying oven), double-sided aluminum powder slurry coating and drying are performed on high-purity aluminum foil with a thickness of approximately 30μm and a purity ≥99.99%. The uniformly stirred aluminum powder slurry is simultaneously coated on both sides of the aluminum foil at a coating speed of 25m / min, with a wet film thickness of 62μm. The coated aluminum foil is then immediately placed in a multi-stage gradient heating hot air circulating drying oven: dried by baking at 78℃ for 25 seconds, 108℃ for 100 seconds, and 108℃ for 28 seconds, to obtain a substrate-dry film composite with a dry film moisture content of 0.36%.

[0111] S5. The dried substrate-dry film composite is placed in a bell-type sintering furnace. The sintering process is carried out in three stages: vacuum treatment, heating treatment, and heat preservation treatment. First, the temperature is raised to 290℃ at a rate of 20℃ / min and held for 1 hour. Then, in an argon atmosphere, the temperature is raised to 490℃ at a rate of 20℃ / min and held for 2 hours, and then raised to 648℃ and held for 2 hours. Finally, the temperature is lowered at a rate of 20℃ / min to obtain the sintered film layer.

[0112] S6. After sintering, the product undergoes formation treatment at 25℃ and 520Vf. The specific capacitance is 1.0μF / cm² with a fluctuation of 8%. It can be bent 60 times without cracking or peeling of the film layer after bending, and the leakage current is 3μA / cm².

[0113] Example 10

[0114] This embodiment describes a method for preparing a high-performance sintered foil using multi-size aluminum powder for industrial production, comprising the following steps:

[0115] S1. Select 5-6μm (50%) and 8-9μm (50%) spherical aluminum powders in a mass ratio of 1:1 and mix them to obtain raw material aluminum powder.

[0116] S2. Using terpineol and n-butanol in a mass ratio of 2:1 as solvent, and ethyl cellulose and polyvinyl acetate in a mass ratio of 1:2 as binder, the solvent to binder ratio is 95:5. Stir at 90℃ for 38 min to form a presolvent. Use PEG6000 and guar gum in a mass ratio of 1:1 as thickener, and mix with the presolvent at a mass ratio of 1.4:100. Stir at 85℃ for 27 min to prepare a thickening solvent. Then, at this temperature, add raw material aluminum powder in a mass ratio of 4:6 of thickening solvent to aluminum powder to obtain an aluminum powder slurry.

[0117] S3. Place the aluminum powder slurry obtained in step 2 into a vacuum double planetary mixer, set the vacuum degree to -0.094MPa, first stir at a low speed of 800r / min for 1h, then stir at a medium speed of 1700r / min for 2h, and finally stir at a high speed of 4500r / min for 1.4h to make the slurry viscosity reach 7500mPa・s.

[0118] S4. Using a micro-gravure coating machine or a comma-shaped doctor blade coating machine (integrated with an online drying oven), double-sided aluminum powder slurry coating and drying are performed on high-purity aluminum foil with a thickness of approximately 30μm and a purity ≥99.99%. The uniformly stirred aluminum powder slurry is simultaneously coated on both sides of the aluminum foil at a coating speed of 28m / min, with a wet film thickness of 64μm. The coated aluminum foil is then immediately placed in a multi-stage gradient heating hot air circulating drying oven: successively baked at 78℃ for 28 seconds, at 108℃ for 110 seconds, and at 108℃ for 29 seconds, until the moisture content of the dry film is reduced to 0.32%.

[0119] S5. The dried substrate-dry film composite is placed in a bell-type sintering furnace. The sintering process is carried out in three stages: vacuum treatment, heating treatment, and heat preservation treatment. The temperature is raised to 280℃ at a rate of 18℃ / min and held for 5 hours. After argon gas is introduced, the temperature is raised to 480℃ at a rate of 18℃ / min and held for 10 hours. Then, the temperature is raised to 645℃ at the same rate and held for 12 hours. Finally, the temperature is lowered at a rate of 18℃ / min to obtain the sintered film layer.

[0120] S6. After sintering, the product undergoes formation treatment at 25℃ and 520Vf. The final product has a specific capacitance of 1.18μF / cm² with a fluctuation of 5.5%, can be bent 95 times without cracking or peeling of the film layer after bending, and has a leakage current of 1μA / cm².

[0121] Example 11

[0122] This embodiment describes a method for preparing a high-performance sintered foil using multi-size aluminum powder for industrial production, comprising the following steps:

[0123] S1. Use 1-2μm (25%) and 7-8μm (75%) spherical aluminum powders in a mass ratio of 1:3 and mix them to obtain raw material aluminum powder.

[0124] S2. Using a mixture of terpineol and methanol at a mass ratio of 3:1 as the solvent, and ethyl cellulose and styrene-butadiene rubber at a mass ratio of 2:1 as the binder, the solvent to binder mass ratio is 97:3. Stir at 72℃ for 30 min. Use PEG6000 and gum arabic at a mass ratio of 3:1 as the thickener, and mix with the presolvent at a mass ratio of 0.55:100. Stir at 62℃ for 21 min. Prepare the slurry according to a solvent to aluminum powder mass ratio of 4:6.

[0125] S3. Place the aluminum powder slurry obtained in S2 into a vacuum double planetary mixer, set the vacuum degree to -0.081MPa, stir at a low speed of 520r / min for 0.55h, a medium speed of 1200r / min for 1.1h, and a high speed of 2200r / min for 0.55h, until the slurry viscosity reaches 2200mPa・s.

[0126] S4. Using a micro-gravure coating machine or a comma-shaped doctor blade coating machine (integrated with an online drying oven), double-sided aluminum powder slurry coating and drying are performed on high-purity aluminum foil with a thickness of approximately 30μm and a purity ≥99.99%. The uniformly stirred aluminum powder slurry is simultaneously coated on both sides of the aluminum foil at a coating speed of 2m / min, with a wet film thickness of 46μm. The coated aluminum foil is then immediately placed in a multi-stage gradient heating hot air circulating drying oven: it is baked at 62℃ for 6 seconds, at 90℃ for 12 seconds, and at 90℃ for 16 seconds to obtain a substrate-dry film composite with a dry film moisture content of 0.48%.

[0127] S5. The dried substrate-dry film composite is placed in a bell-type sintering furnace. The sintering process is carried out in three stages: vacuum treatment, heating treatment, and heat preservation treatment. The temperature is increased to 210℃ at 6℃ / min and held for 1.5h. After air is introduced, the temperature is increased to 410℃ at 6℃ / min and held for 2.5h. Then argon gas is introduced and the temperature is increased to 632℃ at 6℃ / min and held for 2.5h. Finally, the temperature is decreased at 6℃ / min to obtain the sintered film layer.

[0128] S6. After sintering, the product undergoes formation treatment at 25℃ and 520Vf. The specific capacitance is 0.85μF / cm² with a fluctuation of 8%. It can be bent 41 times without cracking or peeling of the film layer after bending, and the leakage current is 2.9μA / cm².

[0129] Example 12

[0130] This embodiment describes a method for preparing a high-performance sintered foil using multi-size aluminum powder for industrial production, comprising the following steps:

[0131] S1. Select spherical aluminum powder with a mass ratio of 3:2 (60% of 4-5μm and 40% of 9-10μm) and mix them to obtain raw aluminum powder.

[0132] S2. Using terpineol and ethanol in a mass ratio of 1:3 as solvent, and ethyl cellulose and polyvinylidene fluoride in a mass ratio of 1:3 as binder, with a solvent-to-binder mass ratio of 95:5, the mixture is stirred at 98°C for 40 min to form a pre-solvent. The thickener is a mixture of PEG6000 and xanthan gum in a mass ratio of 1:3, which is then mixed with the pre-solvent at a mass ratio of 1.5:100 and stirred at 88°C for 29 min to prepare a thickening solvent. Subsequently, aluminum powder is added at this temperature, with the thickening solvent to aluminum powder mass ratio of 2:8 to prepare an aluminum powder slurry.

[0133] S3. Place the aluminum powder slurry obtained in S2 into a vacuum double planetary mixer, set the vacuum degree to -0.095MPa, stir at a low speed of 780r / min for 0.95h, stir at a medium speed of 1800r / min for 2h, and stir at a high speed of 4900r / min for 1.45h, and the viscosity of the aluminum powder slurry reaches 7900mPa・s.

[0134] S4. Using a micro-gravure coating machine or a comma-shaped doctor blade coating machine (integrated with an online drying oven), double-sided aluminum powder slurry coating and drying are performed on high-purity aluminum foil with a thickness of approximately 30μm and a purity ≥99.99%. The uniformly stirred aluminum powder slurry is simultaneously coated on both sides of the aluminum foil at a coating speed of 29m / min, with a wet film thickness of 65μm. The coated aluminum foil is then immediately placed in a multi-stage gradient heating hot air circulating drying oven: sequentially baked at 79℃ for 29 seconds, at 110℃ for 118 seconds, and at 110℃ for 29 seconds to obtain a substrate-dry film composite with a dry film moisture content of 0.3%.

[0135] S5. The dried substrate-dry film composite is placed in a bell-type sintering furnace. The sintering process is carried out in three stages: vacuum treatment, heating treatment, and heat preservation treatment. The temperature is increased to 295℃ at 19℃ / min and held for 4.8h. After argon gas is introduced, the temperature is increased to 495℃ at 19℃ / min and held for 9.8h. Then the temperature is increased to 649℃ at 19℃ / min and held for 11.8h. Finally, the temperature is decreased at 19℃ / min to obtain the sintered film layer.

[0136] S6. After sintering, the product undergoes formation treatment at 25℃ and 520Vf. The specific capacitance is 1.2μF / cm² with a fluctuation of 5%. It can be bent 98 times without cracking or peeling of the film layer after bending, and the leakage current is 1μA / cm².

[0137] Example 13

[0138] This embodiment describes a method for preparing a high-performance sintered foil using multi-size aluminum powder for industrial production, comprising the following steps:

[0139] S1. Use 2-3μm (15%) and 6-7μm (85%) spherical aluminum powders in a mass ratio of 3:17 and mix them to obtain raw material aluminum powder.

[0140] S2. Using a mixture of terpineol and isopropanol at a mass ratio of 1:4 as a solvent, and ethyl cellulose and polyvinyl alcohol at a mass ratio of 4:1 as a binder, with a solvent-to-binder mass ratio of 96.5:3.5, the mixture is stirred at 75°C for 32 minutes to form a pre-solvent. The thickener is a combination of PEG6000 and hydroxypropyl methylcellulose at a mass ratio of 4:1, which is mixed with the pre-solvent at a mass ratio of 0.6:100 and stirred at 65°C for 22 minutes to prepare a thickening solvent. The aluminum powder slurry is prepared according to a thickening solvent-to-aluminum powder mass ratio of 4:6.

[0141] S3. Place the aluminum powder slurry obtained in S2 into a vacuum double planetary mixer, set to a vacuum degree of -0.083MPa, stir at a low speed of 540r / min for 0.6h, a medium speed of 1300r / min for 1.3h, and a high speed of 2000r / min for 0.6h, until the viscosity of the aluminum powder slurry reaches 2500mPa・s.

[0142] S4. Using a micro-gravure coating machine or a comma-shaped doctor blade coating machine (integrated with an online drying oven), double-sided aluminum powder slurry coating and drying are performed on high-purity aluminum foil with a thickness of approximately 30μm and a purity ≥99.99%. The uniformly stirred aluminum powder slurry is simultaneously coated on both sides of the aluminum foil at a coating and drying speed of 3m / min, with a wet film thickness of 47μm. The coated aluminum foil is then immediately placed in a multi-stage gradient temperature hot air circulation drying oven: it is baked at 63℃ for 7 seconds, at 93℃ for 15 seconds, and at 93℃ for 17 seconds to obtain a substrate-dry film composite with a dry film moisture content of 0.46%.

[0143] S5. The dried substrate-dry film composite is placed in a bell-type sintering furnace. The sintering process is carried out in three stages: vacuum treatment, heating treatment, and heat preservation treatment. The temperature is increased to 200℃ at 7℃ / min and held for 1.2h. After air is introduced, the temperature is increased to 405℃ at 7℃ / min and held for 2.2h. Then argon gas is introduced and the temperature is increased to 631℃ at 7℃ / min and held for 2.2h. Finally, the temperature is decreased at 7℃ / min to obtain the sintered film layer.

[0144] S6. After sintering, the product undergoes formation treatment at 25℃ and 520Vf. The specific capacitance is 0.86μF / cm², with a fluctuation of 7.8%. It can be bent 40 times without cracking or peeling of the film layer after bending, and the leakage current is 2.85μA / cm².

[0145] Example 14

[0146] This embodiment describes a method for preparing a high-performance sintered foil using multi-size aluminum powder for industrial production, comprising the following steps:

[0147] S1. Select spherical aluminum powder with a mass ratio of 7:3 (3-4μm, accounting for 70%) and 8-9μm, accounting for 30%), and mix them to obtain raw material aluminum powder.

[0148] S2. Using terpineol and n-butanol in a 4:1 mass ratio as solvent, and ethyl cellulose and sodium carboxymethyl cellulose in a 1:4 mass ratio as binder, with a solvent-to-binder mass ratio of 95.5:4.5, the mixture was stirred at 96°C for 37 min to form a pre-solvent. A thickener was prepared by mixing PEG6000 and fumed silica in a 1:4 mass ratio, and then adjusting the mixture with the pre-solvent at a 1.45:100 mass ratio. The mixture was stirred at 86°C for 28 min to form a thickening solvent. Subsequently, aluminum powder was added at this temperature, with the thickening solvent to aluminum powder mass ratio of 5:5 to prepare an aluminum powder slurry.

[0149] S3. Place the aluminum powder slurry obtained in S2 into a vacuum double planetary mixer, set the vacuum degree to -0.094MPa, stir at a low speed of 760r / min for 0.9h, a medium speed of 1750r / min for 1.9h, and a high speed of 5000r / min for 1.5h, until the slurry viscosity reaches 8000mPa・s.

[0150] S4. Using a micro-gravure coating machine or a comma-shaped doctor blade coating machine (integrated with an online drying oven), double-sided aluminum powder slurry coating and drying are performed on high-purity aluminum foil with a thickness of approximately 30μm and a purity ≥99.99%. The uniformly stirred aluminum powder slurry is simultaneously coated on both sides of the aluminum foil at a coating and drying speed of 30m / min, with a wet film thickness of 65μm. The coated aluminum foil is then immediately placed in a multi-stage gradient heating hot air circulating drying oven: sequentially baked at 80℃ for 30 seconds, at 110℃ for 120 seconds, and at 110℃ for 30 seconds, to obtain a substrate-dry film composite with a dry film moisture content of 0.3%.

[0151] S5. The dried substrate-dry film composite is placed in a bell-type sintering furnace. The sintering process is carried out in three stages: vacuum treatment, heating treatment, and heat preservation treatment. The temperature is increased to 300℃ at 20℃ / min and held for 5 hours. After argon gas is introduced, the temperature is increased to 500℃ at 20℃ / min and held for 10 hours. Then the temperature is increased to 650℃ at 20℃ / min and held for 12 hours. Finally, the temperature is decreased at 20℃ / min to obtain the sintered film layer.

[0152] S6. After sintering, the product undergoes formation treatment at 25℃ and 520Vf. The specific capacitance is 1.2μF / cm² with a fluctuation of 5%. It can be bent 100 times without cracking or peeling of the film layer after bending, and the leakage current is 1μA / cm².

[0153] Example 15

[0154] This embodiment describes a method for preparing a high-performance sintered foil using multi-size aluminum powder for industrial production, comprising the following steps:

[0155] S1. Use 1-2μm (40%) and 5-6μm (60%) spherical aluminum powders in a mass ratio of 2:3 and mix them to obtain raw material aluminum powder.

[0156] S2. A solvent was prepared by mixing terpineol and isoamyl alcohol in a 1:1 mass ratio, and a binder was prepared by mixing ethyl cellulose and polyvinyl acetate in a 2:3 mass ratio, with a solvent-to-binder mass ratio of 97:3. The mixture was stirred at 73°C for 33 minutes to form a pre-solvent. A thickener was prepared by mixing PEG6000 and guar gum in a 2:3 mass ratio, and mixing them with the pre-solvent at a 0.7:1 mass ratio. The mixture was stirred at 66°C for 25 minutes to form a thickening solvent. Subsequently, aluminum powder was added at this temperature, and an aluminum powder slurry was prepared by mixing the thickening solvent and the aluminum powder in a 1:9 mass ratio.

[0157] S3. Place the aluminum powder slurry obtained in S2 into a vacuum double planetary mixer, set the vacuum degree to -0.084MPa, stir at a low speed of 560r / min for 0.7h, a medium speed of 1400r / min for 1.4h, and a high speed of 2600r / min for 0.7h, and the viscosity of the aluminum powder slurry reaches 3500mPa・s.

[0158] S4. Using a micro-gravure coating machine or a comma-shaped doctor blade coating machine (integrated with an online drying oven), double-sided aluminum powder slurry coating and drying are performed on high-purity aluminum foil with a thickness of approximately 30μm and a purity ≥99.99%. The uniformly stirred aluminum powder slurry is simultaneously coated on both sides of the aluminum foil at a coating and drying speed of 6m / min, with a wet film thickness of 50μm. The coated aluminum foil is then immediately placed in a multi-stage gradient heating hot air circulation drying oven: it is baked at 66℃ for 12 seconds, at 96℃ for 25 seconds, and at 96℃ for 20 seconds, resulting in a substrate-dry film composite with a dry film moisture content of 0.45%.

[0159] S5. The dried substrate-dry film composite is placed in a bell-type sintering furnace. The sintering process is carried out in three stages: vacuum treatment, heating treatment, and heat preservation treatment. The temperature is increased to 230℃ at 9℃ / min and held for 2.8h. After vacuuming, the temperature is increased to 400℃ at 9℃ / min and held for 3h. Argon gas is introduced and the temperature is increased to 636℃ at 9℃ / min and held for 4.8h. Finally, the temperature is decreased at 9℃ / min to obtain the sintered film layer.

[0160] S6. After sintering, the product undergoes formation treatment at 25℃ and 520Vf. The specific capacitance is 0.88μF / cm² with a fluctuation of 8%. It can be bent 46 times without cracking or peeling of the film layer after bending, and the leakage current is 2.7μA / cm².

[0161] Example 16

[0162] This embodiment describes a method for preparing a high-performance sintered foil using multi-size aluminum powder for industrial production, comprising the following steps:

[0163] S1. Select spherical aluminum powders with a mass ratio of 7-8μm (35%) and 9-10μm (65%) at a ratio of 7:13, and mix them to obtain raw aluminum powder.

[0164] S2. Using terpineol and ethanol in a 3:2 mass ratio as solvent, and ethyl cellulose and styrene-butadiene rubber in a 3:2 mass ratio as binder, with a solvent-to-binder mass ratio of 95:5, the mixture was stirred at 94°C for 36 min to form a pre-solvent. A thickener was prepared by mixing PEG6000 and gum arabic in a 3:2 mass ratio, and then adjusting the mixture with the pre-solvent at a 1.3:100 mass ratio. The mixture was stirred at 84°C for 25 min to form a thickening solvent. Subsequently, aluminum powder was added at this temperature, with the thickening solvent to aluminum powder mass ratio of 4:6 to prepare an aluminum powder slurry.

[0165] S3. Place the aluminum powder slurry obtained in S2 into a vacuum double planetary mixer, set the vacuum degree to -0.092MPa, stir at a low speed of 720r / min for 0.8h, a medium speed of 1600r / min for 1.6h, and a high speed of 3800r / min for 1.1h, and the viscosity of the aluminum powder slurry reaches 6500mPa・s.

[0166] S4. Using a micro-gravure coating machine or a comma-shaped doctor blade coating machine (integrated with an online drying oven), double-sided aluminum powder slurry coating and drying are performed on high-purity aluminum foil with a thickness of approximately 30μm and a purity ≥99.99%. The uniformly stirred aluminum powder slurry is simultaneously coated on both sides of the aluminum foil at a coating and drying speed of 20m / min, with a wet film thickness of 60μm. The coated aluminum foil is then immediately placed in a multi-stage gradient heating hot air circulation drying oven: sequentially baked at 74℃ for 20 seconds, at 104℃ for 80 seconds, and at 104℃ for 24 seconds, resulting in a substrate-dry film composite with a dry film moisture content of 0.37%.

[0167] S5. The dried substrate-dry film composite is placed in a bell-type sintering furnace. The sintering process is carried out in three stages: vacuum treatment, heating treatment, and heat preservation treatment. The temperature is increased to 270℃ at 16℃ / min and held for 4.2h. After argon gas is introduced, the temperature is increased to 500℃ at 16℃ / min and held for 9.5h. Then the temperature is increased to 643℃ at 16℃ / min and held for 10.5h. Finally, the temperature is decreased at 16℃ / min to obtain the sintered film layer.

[0168] S6. After sintering, the product undergoes formation treatment at 25℃ and 520Vf. The specific capacitance is 1.12μF / cm² with a fluctuation of 5%. It can be bent 88 times without cracking or peeling of the film layer after bending, and the leakage current is 1.3μA / cm².

[0169] Example 17

[0170] This embodiment describes a method for preparing a high-performance sintered foil using multi-size aluminum powder for industrial production, comprising the following steps:

[0171] S1. Use 2-3μm (55%) and 4-5μm (45%) spherical aluminum powders in a mass ratio of 11:9 and mix them to obtain raw material aluminum powder.

[0172] S2. A pre-solvent was prepared by mixing terpineol and methanol in a 2:1 mass ratio as a solvent, and ethyl cellulose and polyvinyl alcohol in a 1:1 mass ratio as a binder, with a solvent-to-binder mass ratio of 96.8:3.2. The mixture was stirred at 78°C for 34 minutes. A thickener was prepared by combining PEG6000 and hydroxypropyl methylcellulose in a 1:1 mass ratio, and mixing them with the pre-solvent at a mass ratio of 0.8:100. The mixture was stirred at 68°C for 24 minutes. Then, aluminum powder was added at this temperature, with the thickener-to-aluminum powder mass ratio at 3:7 to prepare an aluminum powder slurry.

[0173] S3. Place the aluminum powder slurry obtained in S2 into a vacuum double planetary mixer, set the vacuum degree to -0.086MPa, stir at a low speed of 580r / min for 0.75h, a medium speed of 1500r / min for 1.5h, and a high speed of 2900r / min for 0.8h, until the viscosity of the aluminum powder slurry reaches 4000mPa・s.

[0174] S4. Using a micro-gravure coating machine or a comma-shaped doctor blade coating machine (integrated with an online drying oven), double-sided aluminum powder slurry coating and drying are performed on high-purity aluminum foil with a thickness of approximately 30μm and a purity ≥99.99%. The uniformly stirred aluminum powder slurry is simultaneously coated on both sides of the aluminum foil at a coating and drying speed of 10m / min, with a wet film thickness of 52μm. The coated aluminum foil is then immediately placed in a multi-stage gradient heating hot air circulating drying oven: it is baked at 68℃ for 16 seconds, at 98℃ for 35 seconds, and at 98℃ for 22 seconds, resulting in a substrate-dry film composite with a dry film moisture content of 0.43%.

[0175] S5. The dried substrate-dry film composite is placed in a bell-type sintering furnace. The sintering process is carried out in three stages: vacuum treatment, heating treatment, and heat preservation treatment. The temperature is increased to 245℃ at 11℃ / min and held for 3.2h. After air is introduced, the temperature is increased to 445℃ at 11℃ / min and held for 5.5h. Then argon gas is introduced and the temperature is increased to 630℃ at 11℃ / min and held for 5.2h. Finally, the temperature is decreased at 11℃ / min to obtain the sintered film layer.

[0176] S6. After sintering, the product undergoes formation treatment at 25℃ and 520Vf. The specific capacitance is 0.9μF / cm², with a fluctuation of 7.2%. It can be bent 50 times without cracking or peeling of the film layer after bending, and the leakage current is 3μA / cm².

[0177] Example 18

[0178] This embodiment describes a method for preparing a high-performance sintered foil using multi-size aluminum powder for industrial production, comprising the following steps:

[0179] S1. Select 6-7μm (45%) and 8-9μm (55%) spherical aluminum powders with a mass ratio of 9:11 and mix them to obtain raw material aluminum powder.

[0180] S2. Using terpineol and isopropanol in a 3:2 mass ratio as solvent, and ethyl cellulose and polyvinylidene fluoride in a 2:1 mass ratio as binder, with a solvent-to-binder mass ratio of 95.2:4.8, the mixture was stirred at 92°C for 35 min to form a pre-solvent. A thickener was prepared by mixing PEG6000 and fumed silica in a 2:1 mass ratio, and then adjusting the mixture with the pre-solvent at a 1.4:100 mass ratio. The mixture was stirred at 82°C for 25 min to form a thickening solvent. Subsequently, aluminum powder was added at this temperature, with the thickening solvent to aluminum powder mass ratio of 1:9 to prepare an aluminum powder slurry.

[0181] S3. Place the aluminum powder slurry obtained in S2 into a vacuum double planetary mixer, set the vacuum degree to -0.093MPa, stir at a low speed of 740r / min for 0.85h, a medium speed of 1650r / min for 1.7h, and a high speed of 4100r / min for 1.2h, until the slurry viscosity reaches 7000mPa・s.

[0182] S4. Using a micro-gravure coating machine or a comma-shaped doctor blade coating machine (integrated with an online drying oven), double-sided aluminum powder slurry coating and drying are performed on high-purity aluminum foil with a thickness of approximately 30μm and a purity ≥99.99%. The uniformly stirred aluminum powder slurry is simultaneously coated on both sides of the aluminum foil at a coating and drying speed of 24m / min, with a wet film thickness of 63μm. The coated aluminum foil is then immediately placed in a multi-stage gradient heating hot air circulating drying oven: sequentially baked at 76℃ for 24 seconds, at 106℃ for 95 seconds, and at 106℃ for 26 seconds, resulting in a substrate-dry film composite with a dry film moisture content of 0.34%.

[0183] S5. The dried substrate-dry film composite is placed in a bell-type sintering furnace. The sintering process is carried out in three stages: vacuum treatment, heating treatment, and heat preservation treatment. The temperature is increased to 285℃ at 17℃ / min and held for 4.6h. After argon gas is introduced, the temperature is increased to 485℃ at 17℃ / min and held for 9.2h. Then the temperature is increased to 650℃ at 17℃ / min and held for 11.8h. Finally, the temperature is decreased at 17℃ / min to obtain the sintered film layer.

[0184] S6. After sintering, the product undergoes formation treatment at 25℃ and 520Vf. The specific capacitance is 1.16μF / cm² with a fluctuation of 5.2%. It can be bent 92 times without cracking or peeling of the film layer after bending, and the leakage current is 1μA / cm².

[0185] Example 19

[0186] This embodiment describes a method for preparing a high-performance sintered foil using multi-size aluminum powder for industrial production, comprising the following steps:

[0187] S1. Select spherical aluminum powders with a mass ratio of 1:2:3:4, including 1-2μm (10%), 3-4μm (20%), 6-7μm (30%), and 9-10μm (40%).

[0188] S2. The solvent is a mixture of terpineol, isoamyl alcohol, and ethanol in a mass ratio of 2:1:1. The binder is a mixture of ethyl cellulose, polyvinyl alcohol, and styrene-butadiene rubber in a mass ratio of 2:1:1. The solvent to binder mass ratio is 96.5:3.5. The mixture is stirred at 76℃ for 35 min to form a pre-solvent. The thickener is a mixture of PEG6000, hydroxypropyl methylcellulose, and guar gum in a mass ratio of 2:1:1. The thickener is mixed with the pre-solvent in a mass ratio of 0.9:100. The mixture is stirred at 69℃ for 25 min to form a thickening solvent. Subsequently, aluminum powder is added at this temperature, maintaining a mass ratio of thickening solvent to raw solvent to aluminum powder of 4:6 to prepare an aluminum powder slurry.

[0189] S3. Place the aluminum powder slurry obtained in S2 into a vacuum double planetary mixer, set the vacuum degree to -0.087MPa, and stir at a low speed of 590r / min for 0.8h, a medium speed of 1450r / min for 1.6h, and a high speed of 3000r / min for 0.9h in sequence, so that the viscosity of the aluminum powder slurry reaches 4500mPa・s.

[0190] S4. Using a micro-gravure coating machine or a comma-shaped doctor blade coating machine (integrated with an online drying oven), double-sided aluminum powder slurry coating and drying of high-purity aluminum foil with a thickness of approximately 30 μm and a purity ≥99.99% is performed. The uniformly stirred aluminum powder slurry is coated at a speed of 12 m / min, resulting in a wet film thickness of 53 μm. The coated aluminum foil is then immediately placed in a multi-stage gradient heating hot air circulating drying oven: dried at 69℃ for 18 seconds, 99℃ for 40 seconds, and 99℃ for 24 seconds, achieving a dry film moisture content of 0.5%. The sintering process involves heating at 12℃ / min to 250℃ and holding for 3.5 hours, then introducing air and continuing to heat at 12℃ / min to 450℃ and holding for 6 hours, followed by introducing argon gas and heating at 12℃ / min to 638℃ and holding for 6 hours, and finally cooling at 12℃ / min to obtain the sintered film layer.

[0191] S6. After sintering, the product undergoes formation treatment at 25℃ and 520Vf. The specific capacitance is 0.87μF / cm², with a fluctuation of 7.8%. It can be bent 40 times without cracking or peeling of the film layer after bending, and the leakage current is 2.9μA / cm².

[0192] Example 20

[0193] This embodiment describes a method for preparing a high-performance sintered foil using multi-size aluminum powder for industrial production, comprising the following steps:

[0194] S1. Use spherical aluminum powders of 1-2μm (8%), 2-3μm (12%), 4-5μm (25%), 7-8μm (25%) and 9-10μm (30%) in a mass ratio of 8:12:25:25:30, and mix them to obtain raw material aluminum powder.

[0195] S2. In the slurry preparation stage, the mass ratio of solvent (terpineol:methanol:isopropanol = 3:1:1, mass ratio) to binder (ethyl cellulose:polyvinylidene fluoride:sodium carboxymethyl cellulose = 3:1:1, mass ratio) is 95.8:4.2, and the mixture is stirred at 93℃ for 38 min to form a pre-solvent; the mass ratio of thickener (PEG6000:fumed silica:gum arabic = 3:1:1, mass ratio) to pre-solvent is 1.4:100, and the mixture is stirred at 83℃ for 30 min to prepare a thickening solvent. Subsequently, at this temperature, raw aluminum powder is added, and the mass ratio of thickening solvent to raw aluminum powder is 2:8 to prepare an aluminum powder slurry.

[0196] S3. Place the aluminum powder slurry obtained in S2 into a vacuum double planetary mixer, control the vacuum degree to -0.091MPa, and stir at low speed 750r / min for 0.95h, medium speed 1700r / min for 1.9h, and high speed 4800r / min for 1.4h in sequence. The final viscosity of the aluminum powder slurry reaches 7800mPa・s.

[0197] S4. Using a micro-gravure coating machine or a comma-shaped doctor blade coating machine (integrated with an online drying oven), double-sided aluminum powder slurry coating and drying are performed on high-purity aluminum foil with a thickness of approximately 30μm and a purity ≥99.99%. The uniformly stirred aluminum powder slurry is simultaneously coated on both sides of the aluminum foil at a speed of 26m / min, with a wet film thickness of 64μm. The coated aluminum foil is then immediately placed in a multi-stage gradient heating hot air circulating drying oven: after a stepped treatment of baking at 77℃ for 26 seconds → baking at 107℃ for 105 seconds → baking at 107℃ for 28 seconds, the moisture content of the dry film is reduced to 0.35% to form a substrate-dry film composite.

[0198] S5. The dried substrate-dry film composite is placed in a bell-type sintering furnace. The sintering process is carried out in three stages: vacuum treatment, heating treatment, and heat preservation treatment. First, the temperature is raised to 290℃ at a rate of 19℃ / min and held for 4.8h. Then, argon gas is introduced, and the temperature is raised to 490℃ at a rate of 19℃ / min and held for 9.8h. Then, the temperature is raised to 649℃ and held for 11.8h. Finally, the temperature is lowered at a rate of 5℃ / min to obtain the sintered film layer.

[0199] S6. After sintering, the final product exhibits the following performance characteristics after formation treatment at 25℃ and 520Vf: specific capacitance of 1.2μF / cm², fluctuation range of 5%, ability to withstand 98 bends without cracking or peeling of the film layer after bending, and leakage current of only 1μA / cm².

[0200] Comparative Example 1

[0201] This embodiment of a method for preparing a sintered foil includes the following steps:

[0202] Spherical aluminum powder with a single particle size of 5-6 μm was selected as the aluminum powder raw material. During the experiment, the slurry preparation, stirring parameters, coating and drying process, and sintering process were all consistent with Example 20, namely, the solvent to binder mass ratio was 95.8:4.2, the thickener to pre-solvent mass ratio was 1.4:100, the stirring vacuum degree was -0.091 MPa, the coating and drying speed was 26 m / min, the wet film thickness was 64 μm, and the same segmented heating / cooling procedure was used for sintering, with formation treatment completed at 25℃ and 520 Vf. However, the final product performance showed significant differences: although the specific capacitance was the same at 1.2 μF / cm² with a fluctuation of 5%, its bending resistance decreased significantly, only able to withstand two bends, and the leakage current increased to 2.5 μA / cm².

[0203] The foregoing has shown and described the main features and advantages of the present invention. It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

[0204] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A high-performance sintered foil composed of multi-size aluminum powder for industrial production, characterized in that, The sintered foil is prepared by mixing aluminum powders of various particle sizes, followed by slurry preparation, slurry stirring, double-sided coating and drying, sintering, and formation treatment. The standardized specific capacitance of the sintered foil is 0.8-1.2 μF / cm², with a specific capacitance fluctuation of ≤8%. It withstands 40-100 bends after a 90° bend test without cracking or peeling of the film layer. The leakage current is ≤3 μA / cm² under rated voltage and at 25°C. 2 .

2. The high-performance sintered foil with multi-size aluminum powder for industrial production according to claim 1, characterized in that, The multi-particle-size aluminum powder mixing and matching is achieved by mixing any two or more aluminum powders within the particle size range of 1-2μm, 2-3μm, 3-4μm, 4-5μm, 5-6μm, 6-7μm, 7-8μm, 8-9μm, and 9-10μm.

3. The method for preparing a high-performance sintered foil with multi-size aluminum powder for industrial production as described in claim 1 or 2, characterized in that, Includes the following steps: Step 1: Select aluminum powders of different particle size ranges and mix them to obtain raw aluminum powder; Step 2: Mix the solvent and binder, heat and stir to form a pre-solvent, then add the thickener, continue heating and stirring, then add the raw material aluminum powder, and stir to obtain an aluminum powder slurry that meets the coating viscosity requirements; Step 3: Vacuum stirring is performed on the aluminum powder slurry obtained in Step 2. The vacuum stirring is divided into three stages: low-speed stirring, medium-speed stirring and high-speed stirring. Step 4: Simultaneously coat the stirred aluminum powder slurry onto both sides of the aluminum foil. The coated aluminum foil is then dried in a multi-stage gradient heating process to obtain a substrate-dry film composite. Step 5: Sinter the substrate-dry film composite. The sintering process is divided into three stages: vacuum treatment, heating treatment, and heat preservation treatment, to obtain the sintered film layer. Step 6: Perform a formation treatment on the sintered film layer.

4. The method for preparing a high-performance sintered foil with multi-size aluminum powder for industrial production according to claim 3, characterized in that, Step 1 specifically involves: Spherical or near-spherical aluminum powders with particle sizes in the ranges of 1-2μm, 2-3μm, 3-4μm, 4-5μm, 5-6μm, 6-7μm, 7-8μm, 8-9μm, and 9-10μm are selected, and any two or more aluminum powders in the above ranges are mixed together.

5. The method for preparing a high-performance sintered foil with multi-size aluminum powder for industrial production according to claim 3, characterized in that, Step 2 specifically involves: The solvent and binder are mixed at a mass ratio of 95-97:3-5 and heated and stirred at 70-100℃ to form a pre-solvent. Then, a thickener is added at a mass ratio of 0.5-5:100 to the pre-solvent, and the mixture is heated and stirred at 60-90℃ to form a thickening solvent. Subsequently, aluminum powder is added at this temperature at a mass ratio of 1-7:3-9 to the thickening solvent.

6. A method for preparing a high-performance sintered foil with multi-size aluminum powder for industrial production according to claim 3 or 5, characterized in that, The solvent is terpineol, the binder is ethyl cellulose, and the thickener is PEG6000.

7. The method for preparing a high-performance sintered foil with multi-size aluminum powder for industrial production according to claim 6, characterized in that, The solvent may also be combined with any one or more of methanol, ethanol, isopropanol, n-butanol, and isoamyl alcohol; the binder may also be combined with any one or more of polyvinylidene fluoride, polyvinyl alcohol, sodium carboxymethyl cellulose, styrene-butadiene rubber, and polyvinyl acetate; the thickener may also be combined with any one or more of hydroxypropyl methylcellulose, xanthan gum, fumed silica, guar gum, and gum arabic.

8. The method for preparing a high-performance sintered foil with multi-size aluminum powder for industrial production according to claim 3, characterized in that, Step 3 specifically involves: The aluminum powder slurry obtained in step 2 was subjected to vacuum stirring, with the vacuum level set to -0.08MPa to -0.095MPa. The vacuum environment was used to defoam the aluminum powder slurry. The stirring speed was divided into three stages: low speed stage with a speed of 500-800 r / min and a stirring time of 0.5-1 h; medium speed stage with a speed of 1200-1800 r / min and a stirring time of 1-2 h; and high speed stage with a speed of 2000-5000 r / min and a stirring time of 0.5-1.5 h. Through vacuum defoaming, the viscosity of the aluminum powder slurry was ensured to be stable within the range of 2000-8000 mPa·s.

9. The method for preparing a high-performance sintered foil with multi-size aluminum powder for industrial production according to claim 3, characterized in that, Step 4 specifically involves: The stirred aluminum powder slurry was simultaneously coated onto both sides of the aluminum foil at a speed of 1.5-30 m / min, with the wet film thickness controlled at 45-65 μm. The coated aluminum foil was then subjected to multi-stage gradient heating and drying: the first stage was drying at 60-80℃ for 5-30 seconds; the second stage was heating up to 90-110℃ and drying for 10-120 seconds; the third stage was drying at 90-110℃, finally obtaining a substrate-dry film composite with a dry film moisture content ≤0.5%.

10. The method for preparing a high-performance sintered foil with multi-size aluminum powder for industrial production according to claim 3, characterized in that, Step 5 specifically involves: The substrate-dry film composite is sintered. The sintering process is divided into three stages: vacuum treatment, heating treatment, and heat preservation treatment. In the first stage, vacuum treatment is carried out, and the temperature is raised to 200-300℃ at a rate of 5-20℃ / min and held for 1-5 hours. In the second stage, air, argon gas with a purity ≥99.999%, or a vacuum state are introduced, and the temperature is increased to 400-500℃ at a rate of 5-20℃ / min, and held for 2-10 hours. In the third stage, argon gas with a purity ≥99.999% is introduced, and the temperature is increased to 630-650℃ at a rate of 5-20℃ / min, and held for 2-12 hours. After the third stage is completed, the temperature is decreased at a rate of 5-20℃ / min to finally obtain the sintered film layer.

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