Aluminum foil for solid-state battery and preparation method thereof

Abstract

The invention discloses an aluminum foil for a solid-state battery and a preparation method thereof, and the method comprises the following steps: S1, preparing a cast-rolling blank from a raw material formula by adopting a cast-rolling method; the raw material formula comprises the following components in percentage by mass: less than or equal to 0.10% of Si, less than or equal to 0.35% of Fe, 0.40-0.60% of Mn and Mglt; 0.01%, and the balance being Al; s2, the cast-rolled blank is subjected to cold rolling, and a cold-rolled strip is obtained; s3, the cold-rolled strip is subjected to foil rolling, and an aluminum foil material is obtained; and S4, slitting the aluminum foil material to obtain the aluminum foil for the solid-state battery. The thickness of the aluminum foil for the solid-state battery prepared through the method is 0.008-0.010 mm, the tensile strength is larger than 250 MPa, the percentage elongation after fracture is larger than or equal to 7.0%, the pinhole quality and the surface quality are good, and the requirement of a new generation of solid-state batteries for the aluminum foil can be met.

Description

Technical Field

[0001] This invention relates to the field of aluminum processing technology, and in particular to an aluminum foil for solid-state batteries and its preparation method. Background Technology

[0002] Solid-state batteries operate on the same principle as traditional liquid lithium batteries. The electrolyte in a solid-state battery is solid, and its density and structure allow more charged ions to accumulate at one end, thus conducting a larger current and increasing battery capacity. Therefore, for the same amount of energy, solid-state batteries are smaller. Furthermore, because there is no electrolyte in solid-state batteries, sealing them is easier. When used in large equipment such as automobiles, there is no need for additional cooling pipes and electronic controls, saving costs and effectively reducing weight. Solid-state electrolytes not only increase battery energy density but also reduce the risk of battery failure at extreme temperatures due to their stable chemical properties, representing a significant leap in safety.

[0003] When aluminum foil is used in solid-state batteries: its high conductivity significantly improves the charge transport efficiency of the electrodes, ensuring stable discharge capability under high load conditions; as an electrode substrate, aluminum foil effectively maintains the integrity of the electrode's layered structure, preventing the active material from peeling or deforming during cycling; the aluminum foil layer can block direct contact between the solid electrolyte and the electrode material, avoiding side reactions and thus extending battery cycle life; the excellent thermal conductivity of aluminum foil helps dissipate heat during battery operation, improving temperature uniformity; and its good flexibility allows it to adapt to various electrode fabrication processes, including coating and calendering techniques.

[0004] Although aluminum foil can improve the performance of solid-state batteries, the aluminum foil used in related technologies is thicker than 0.01 mm, has a tensile strength of 190~250 MPa, an elongation after fracture of less than 7.0%, and poor pinhole and surface quality, which cannot meet the requirements of the next generation of solid-state batteries for aluminum foil. Summary of the Invention

[0005] The purpose of this invention is to provide an aluminum foil for solid-state batteries and a method for preparing the same, so as to solve the problem that aluminum foil in related technologies cannot meet the requirements of next-generation solid-state batteries.

[0006] In a first aspect, embodiments of the present invention provide a method for preparing aluminum foil for solid-state batteries, comprising the following steps: Step S1: Prepare a cast-rolled billet with a thickness of 6.600~7.000 mm using the cast-rolling method based on the raw material formula; The raw material formula has the following composition and mass percentage: Si≤0.10%, Fe≤0.35%, Mn=0.40~0.60%, Mg<0.01%, with the balance being Al; wherein, element Si is prepared using an Al-Si master alloy with a Si content of 10.50~11.50%, element Fe is prepared using an AlFe20 master alloy and an aluminum-type iron agent, and element Al is prepared using remelted aluminum ingots with Na≤8ppm; Step S2: Cold roll the cast-rolled billet to obtain a cold-rolled strip with a thickness of 0.200~0.240mm; Step S3: Foil rolling is performed on the cold-rolled strip to obtain aluminum foil with a thickness of 0.008~0.010mm; Step S4: Cut the aluminum foil to obtain the aluminum foil for solid-state batteries.

[0007] Preferably, the AlFe20 master alloy is a waffle ingot; the element Fe in the AlFe20 master alloy is derived from tinplate; and the iron powder in the aluminum-type iron agent is carbon steel melted and deslag-removed atomized iron powder in spherical form.

[0008] Preferably, in step S1, the casting and rolling method includes the following steps in sequence: preparing the remelted aluminum ingot, smelting, stirring, first refining, first settling, first slag removal, adding metal additives, second settling, second slag removal, furnace turning, second refining, third slag removal, third settling, degassing, filtering, and casting and rolling; the metal additives are elements Si, Fe, and Mn. The smelting, stirring, first refining, first settling, first slag removal, addition of metal additives, second settling, and second slag removal are all carried out in the smelting furnace; the second refining, third slag removal, third settling, and degassing are all carried out in the holding furnace; the furnace pouring is the process of pouring the molten aluminum from the smelting furnace after the second slag removal into the holding furnace. The casting and rolling method is a continuous preparation process, the frequency of the first refining is 3~4 hours / time, and the frequency of stirring is 2~3 hours / time.

[0009] Preferably, the filtration uses a two-stage filtration system consisting of a 60-mesh filter plate and a 70-mesh filter plate. The composition and mass percentage of the 60-mesh and 70-mesh filter plates are as follows: alumina = 85.00~86.00%, silicon dioxide = 5.00~6.00%, aluminum dihydrogen phosphate = 5.00~6.00%, with the balance being sintered NaO and CaO. Both the 60-mesh and 70-mesh filter plates are covered with 4~6mm thick expanded cotton on their periphery. The 60-mesh and 70-mesh filter plates are preheated before filtration and maintained at a temperature of 550℃~650℃. The air pressure used for the 60-mesh filter plate is 1150~1250Pa, and the air pressure used for the 70-mesh filter plate is 1400~1500Pa.

[0010] Preferably, the casting and rolling process is subjected to electromagnetic magnetic field oscillation.

[0011] Preferably, in step S2, the cold rolling is performed using a cold rolling mill; the rolling oil used in the cold rolling mill has a weight of 130g / m 2 The rolling oil is filtered through a filter cloth; the rolling oil used in the cold rolling mill contains a reducing stabilizer at a weight of 0.20~0.40% of the rolling oil.

[0012] Preferably, in step S2, the cold rolling is performed by multiple cold rolling passes to obtain the cold-rolled strip; the uncoiling temperature of the last cold rolling pass is less than 45°C, the rolling speed of the last cold rolling pass is less than 500 m / min, and the exit temperature of the last cold rolling pass is less than 70°C.

[0013] Preferably, in step S3, the aluminum foil is obtained by rolling the foil through four foil rolling passes; the material temperature of the first foil rolling pass is 120°C, the material temperature of the second foil rolling pass is 100°C, the material temperature of the third foil rolling pass is 80°C, and the material temperature of the fourth foil rolling pass is 80°C.

[0014] Preferably, in step S4, the slitting is performed using a vertical slitting machine; the slitting blade of the vertical slitting machine is a tungsten steel disc blade, the vertical slitting machine is equipped with two corona discharge devices, the corona discharge power of the corona discharge devices is 80~100kw; the slitting speed of the vertical slitting machine is 700~800m / min, and the edge burr height of the aluminum foil for solid-state batteries after slitting is less than 0.001mm; before using the vertical slitting machine, the disc blade is lubricated with a lubricant with a liquid pour point of -25~-30℃; the convexity of the rubber roller in the vertical slitting machine is 0.100~0.150mm, and the roller surface pressure of the rubber roller in the vertical slitting machine is 2.0~2.5N.

[0015] Secondly, embodiments of the present invention provide an aluminum foil for solid-state batteries, which is made by the above-described method for preparing aluminum foil for solid-state batteries.

[0016] Compared with the prior art, the method for preparing aluminum foil for solid-state batteries in this invention, by defining the raw material formula and sequentially using casting-rolling, cold rolling, foil rolling and slitting processes, can produce aluminum foil for solid-state batteries with a thickness of 0.008~0.010mm, a tensile strength greater than 250MPa, an elongation after fracture greater than or equal to 7.0%, and excellent pinhole and surface quality, thus meeting the requirements of the next generation of solid-state batteries for aluminum foil. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort, wherein: Figure 1 This is a schematic flowchart illustrating the steps of a method for preparing aluminum foil for solid-state batteries according to an embodiment of the present invention. Figure 2 Metallographic diagram of a substandard Al-Si master alloy; Figure 3 This is a metallographic image of the Al-Si master alloy in an embodiment of the present invention; Figure 4 This is a schematic diagram of the surface microcracks of the aluminum foil used in solid-state batteries in an embodiment of the present invention. Detailed Implementation

[0018] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] This invention provides a method for preparing aluminum foil for solid-state batteries, combined with... Figure 1 As shown, it includes the following steps: Step S1: Prepare a cast-rolled billet with a thickness of 6.600~7.000 mm by casting and rolling the raw material formula.

[0020] The raw material formula contains the following components and mass percentages: Si≤0.10%, Fe≤0.35%, Mn=0.40~0.60%, Mg<0.01%, with the balance being Al.

[0021] The elemental Si is prepared using an Al-Si master alloy with a Si content of 10.50~11.50%. This microstructure contains no primary silicon and has excellent microstructure. The α-Al+Si eutectic phase has a melting point of only 577℃, which can be fully melted in molten aluminum at 730~750℃ and uniformly dispersed in the molten aluminum. When the elemental Si content of the Al-Si master alloy is greater than 12%, a large number of primary silicon particles will be obtained, which easily form melt inclusions, ultimately leading to porosity defects in the prepared solid-state battery aluminum foil. Figure 2 As shown, this is a metallographic diagram of a substandard Al-Si master alloy. The black lumps represent primary silicon, which adversely affects the quality of the melt. Figure 3 As shown, it is a metallographic diagram of the Al-Si master alloy in this embodiment. More than 99% of it is α-Al+Si eutectic phase. This structure is excellent and will not produce inclusions, that is, it will not produce pore defects.

[0022] The element Fe was prepared using AlFe20 master alloy and aluminum-type iron agent.

[0023] The Fe element in the AlFe20 master alloy is derived from food-grade tinplate (tin-plated iron). Compared to flux-type additives, the AlFe20 master alloy has fewer impurities, which is beneficial to the melt quality. Furthermore, the AlFe20 master alloy is a waffle ingot, which, compared to traditional long solid ingots, can increase the cooling area and efficiency of the crystallizer, has a superior internal structure, a more dispersed second phase distribution, and a 20-30% reduction in size.

[0024] The iron powder in the aluminum-type iron agent is carbon steel melted and deslag-removed atomized iron powder, which is spherical and has a stable chemical composition; while the traditional rolled steel phosphorus reduction powder is spongy iron powder, which has an unstable chemical composition and a high content of impurity elements such as Mn, O, and C.

[0025] The elemental Al is prepared using remelted aluminum ingots with Na ≤ 8 ppm. The higher the Na content, the more viscous the molten aluminum becomes when preparing the cast-rolled billet using the casting and rolling method.

[0026] The casting and rolling process includes the following steps in sequence: preparing the remelted aluminum ingot, smelting, stirring, first refining, first settling, first slag removal, adding metal additives, second settling, second slag removal, furnace turning, second refining, third slag removal, third settling, degassing, filtration, and casting and rolling. The metal additives are elements Si, Fe, and Mn in the above-mentioned mass fractions. The content of element Mg is low and is introduced by the above-mentioned mass fractions of the remelted aluminum ingot, without being prepared separately.

[0027] The smelting, stirring, first refining, first settling, first slag removal, addition of metal additives, second settling, and second slag removal are all carried out in the smelting furnace; the second refining, third slag removal, third settling, and degassing are all carried out in the holding furnace; the furnace pouring is the process of pouring the molten aluminum from the smelting furnace after the second slag removal into the holding furnace.

[0028] The casting and rolling method is a continuous preparation process. The frequency of the first refining is 3-4 hours / time, the frequency of stirring is 2-3 hours / time, and a forklift is used for stirring. In each continuous preparation process, the stirring is generally carried out 4-5 times.

[0029] The filtration system uses a two-stage filtration system consisting of a 60-mesh filter plate and a 70-mesh filter plate.

[0030] The composition and mass percentage of the 60-mesh filter plate and the 70-mesh filter plate are as follows: alumina = 85.00~86.00%, silicon dioxide = 5.00~6.00%, aluminum dihydrogen phosphate = 5.00~6.00%, and the balance is a sintered product of NaO and CaO. Of course, the sintered product does not only contain NaO and CaO. This limitation ensures that the 60-mesh filter plate and the 70-mesh filter plate are free of foreign matter that would adversely affect the quality of the melt.

[0031] The 60-mesh and 70-mesh filter plates have uniform pore size, are resistant to high temperatures, and do not shed slag or powder. After high-temperature testing, their residual strength is 1.1~1.3MPa, and their residual strength retention rate is greater than or equal to 0.78. These residual strength and residual strength retention rates are relative to room temperature. The residual strength retention rate and residual strength can reflect the filter plate's ability to resist the impact of molten aluminum during high-temperature processes. The higher the residual strength retention rate, the better the thermal performance during use.

[0032] The 60-mesh filter plate uses an air pressure of 1150~1250Pa, and the 70-mesh filter plate uses an air pressure of 1400~1500Pa. Both the 60-mesh and 70-mesh filter plates are preheated to a temperature of 550℃~650℃ before filtration. Preheating ensures smoother flow of the molten aluminum.

[0033] Both the 60-mesh and 70-mesh filter plates are covered with expanding cotton with a thickness of 4-6 mm at room temperature. After heating, the thickness of the expanding cotton expands to about twice its thickness at room temperature, i.e., 8-12 mm, to ensure its sealing performance.

[0034] A dual-stage filter plate can ensure that the filtered product is pure, with a residue content of less than 0.006mm. 2 / kg.

[0035] In conventional casting and rolling processes, rapid crystallization inevitably leads to chemical segregation. However, this embodiment utilizes electromagnetic field oscillation during the casting and rolling process, effectively mitigating the segregation of various alloying elements. When a magnetic field of 0.1 MPa is applied, the grain refiner forms dispersed TiB2 nucleation particles. In contrast, in conventional processes without an electromagnetic field, TiB2 particles agglomerate, forming coarse inclusions that cause porosity in the aluminum foil.

[0036] Step S2: The cast-rolled billet is cold-rolled to obtain a cold-rolled strip with a thickness of 0.200~0.240mm.

[0037] The cold rolling process is carried out using a cold rolling mill.

[0038] The rolling oil used in the cold rolling mill has a weight of 130g / m 2 The filter cloth used to filter the rolling oil; the higher the basis weight, the fewer the gaps in the filter cloth, and the less likely the filter aid and other foreign matter will fall into the rolling oil. The following table shows the results of filtering rolling oil using filter cloths of different basis weights, and analyzing the chemical elements in the rolling oil using XRF fluorescence (X-ray fluorescence) spectroscopy: Table 1. Test Analysis Table

[0039] As shown in Table 1, the content of elements Si and Fe in the rolling oil decreased by more than 80% in 130g of filter cloth compared to 90g of filter cloth. The element Si mainly comes from silica and filter aids such as bleaching clay. Therefore, the rolling oil obtained in this embodiment will not cause defects such as pinholes in the aluminum foil due to foreign matter pressing in.

[0040] During the continuous rolling pressure, the long carbon chains in the aforementioned rolling oil decompose to generate a large number of unsaturated carbon chains. This leads to an increase in carboxylic acids in the rolling oil, a continuous rise in acid value, and ultimately, oxidative deterioration of the rolling oil. In this embodiment, the rolling oil used in the cold rolling mill contains 0.20-0.40% by weight of a reducing stabilizer, i.e., a reducing stabilizer is added. The base bonds in the reducing stabilizer can effectively combine with the unsaturated carbon chains, compensating for the poor lubrication of short carbon chains, and greatly slowing down the aging rate of the rolling oil. Studies have shown that the rolling oil with the added reducing stabilizer has 20-25 minutes higher oxidation stability than the rolling oil without the added reducing stabilizer, and the resulting cold-rolled strip has excellent, uniform, and fine surface quality.

[0041] The cold rolling process involves multiple cold rolling passes to obtain the cold-rolled strip. The uncoiling temperature of the final cold rolling pass is less than 45°C, the rolling speed of the final cold rolling pass is less than 500 m / min, and the exit temperature of the final cold rolling pass is less than 70°C. These limitations ensure that the size of the surface microcracks in the resulting cold-rolled strip is less than 20 μm. If the size of the surface microcracks in the cold-rolled strip is greater than 20 μm, it will reduce the surface quality of the final aluminum foil for solid-state batteries, leading to a decrease in its elongation after break.

[0042] For example, the cold-rolled strip is obtained by rolling through eight cold rolling passes, with the thicknesses rolled in these eight passes sequentially being 6.8mm → 4.2mm → 2.6mm → 1.6mm → 0.9mm → 0.56mm → 0.36mm → 0.24mm → 0.18mm. The following table shows the particle count for each dimension, ensuring the environment during each rolling pass is monitored using a particle counter and meets the requirements for proceeding to the next pass: Table 2. Number of Particles for Each Size

[0043] As can be seen from Table 2, the cold-rolled strip obtained has no foreign matter pressed in, and the pinhole quality of the final solid-state battery aluminum foil is excellent.

[0044] Step S3: Foil rolling is performed on the cold-rolled strip to obtain aluminum foil with a thickness of 0.008~0.010mm.

[0045] The aluminum foil material is obtained by rolling the foil through four passes. The following is a table of parameters for each of the four foil rolling passes: Table 3 and 4: Parameters for Foil Rolling Passes

[0046] The sensitivity of alloys to temperature changes was studied, and the data showed that the elongation at break of aluminum foil varied with the mill temperature as shown in Table 4 below. This involved comparing the elongation at break of the aluminum foil after each rolling pass with the elongation at break after 8 hours of rest. The results showed that the elongation at break decreased with decreasing mill temperature for each rolling pass: 30.5% decrease for the first rolling pass at 120℃; 31.8% decrease for the second at 100℃; 23.6% decrease for the third at 80℃; and a decrease of [missing data] for the fourth at 80℃. A 13.6% decrease in elongation indicates that the inflection point in the decrease in elongation after fracture occurred after the foil rolling mill temperatures (material temperatures) for the four foil rolling passes were 120℃, 100℃, 80℃, and 80℃ respectively. This confirms that the material temperatures for the four foil rolling passes were 120℃, 100℃, 80℃, and 80℃ respectively. Specifically, the material temperature for the first foil rolling pass was 120℃, the second 100℃, the third 80℃, and the fourth 80℃. This ensures that the elongation after fracture of the aluminum foil for solid-state batteries meets the requirements, and the surface microcrack size is less than 10μm. The breakage rate of the aluminum foil for solid-state batteries decreases by approximately 15%. A decrease in elongation after fracture leads to a significant increase in both the number and size of surface microcracks. These microcracks create stress concentration, causing the aluminum foil for solid-state batteries to fracture preferentially at these points during the tensile stage, ultimately rendering the material unusable. The surface microcrack size of aluminum foil used in solid-state batteries was detected using scanning electron microscopy and 3D microscopy. The detected surface microcracks are shown in the figure. Figure 4 As shown.

[0047] Table 4. Comparison of the decrease in elongation after fracture of aluminum foil in each foil rolling pass as a function of material temperature.

[0048] Step S4: Cut the aluminum foil to obtain the aluminum foil for solid-state batteries.

[0049] The slitting is performed using a vertical slitting machine.

[0050] The vertical slitting machine uses a disc blade for slitting, and the slitting speed of the vertical slitting machine is 700~800m / min. After slitting, the edge burr height of the aluminum foil for solid-state batteries is less than 0.001mm, which means that the edge quality is excellent and will not cause the foil to break.

[0051] The vertical slitting machine is equipped with two corona discharge devices with a corona discharge power of 80-100 kW. This heats the aluminum foil to accelerate the evaporation of the surface rolling oil film. If baking is used to detect the oil content of the aluminum foil, the aluminum foil is weighed before baking, then placed in a 300°C oven for 1 hour, removed, and weighed again. The oil content on the surface of the aluminum foil is calculated in milligrams per square meter. In this embodiment, the use of corona discharge devices reduces the surface oil content of the aluminum foil by 60-70%. The surface oil content of the solid-state battery aluminum foil obtained after slitting is below 0.8 milligrams per square meter, and the dyn value can reach above 35 dyn, preventing missed coating during film application.

[0052] The convexity of the rubber roller in the vertical slitting machine is 0.100~0.150mm, which can maintain a slight convexity; the roller surface pressure of the rubber roller in the vertical slitting machine is 2.0~2.5N, which can make the aluminum foil for solid batteries obtained after slitting have a flat and excellent plate shape, and will not cause flashing wrinkles during high-speed slitting.

[0053] The disc cutter is made of tungsten carbide. Tungsten carbide has high hardness, wear resistance, strength and toughness. Its high strength and wear resistance can keep it basically unchanged at 500℃. As a result, its cutting length can be increased by 30-40% compared with other cutter materials. Moreover, the aluminum foil for solid batteries cut by the tungsten carbide disc cutter has excellent edge quality.

[0054] Before use, the vertical slitting machine lubricates the disc blades with a liquid pour point of -25 to -30°C. This reduces aluminum powder generation and has a low flash point, ensuring no oil residue on the edges of the aluminum foil used in solid-state batteries. Furthermore, the surface wetting tension can reach 35 × 10⁻⁶. -3 Above N / m.

[0055] Compared with existing technologies, the method for preparing aluminum foil for solid-state batteries in this invention, by defining the raw material formula and sequentially employing casting-rolling, cold rolling, foil rolling, and slitting processes, produces aluminum foil for solid-state batteries with a thickness of 0.008~0.010mm, tensile strength greater than 250MPa, elongation after break greater than or equal to 7.0%, low breakage rate, excellent pinhole quality, and no defects such as color difference or bright lines, i.e., excellent surface quality, and burr height less than 0.001mm, which can meet the requirements of aluminum foil for next-generation solid-state batteries.

[0056] The present invention also provides another embodiment, an aluminum foil for solid-state batteries, which is made by the preparation method of aluminum foil for solid-state batteries in the above embodiments and is applied to solid-state batteries.

[0057] Since the aluminum foil for solid-state batteries in this embodiment is made by the preparation method of aluminum foil for solid-state batteries in the above embodiment, the aluminum foil for solid-state batteries in this embodiment can also achieve the technical effects achieved by the preparation method of aluminum foil for solid-state batteries in the above embodiment, and will not be elaborated here.

[0058] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A method for producing an aluminum foil for a solid-state battery, characterized by, The method comprises the following steps: Step S1, preparing a cast-rolling blank with a thickness of 6.600-7.000 mm by adopting a cast-rolling rolling method for a raw material formula; Wherein, the components and mass percentage of the raw material formula are: Si≤0.10%, Fe≤0.35%, Mn=0.40-0.60%, Mg<0.01%, and the balance is Al; wherein, element Si is prepared by Al-Si intermediate alloy with Si content of 10.50-11.50%, element Fe is prepared by AlFe20 intermediate alloy and aluminum type iron agent, and element Al is prepared by remelted aluminum ingot with Na≤8ppm; Step S2, cold rolling the cast-rolling blank to obtain a cold-rolled strip with a thickness of 0.200-0.240 mm; Step S3, foil rolling the cold-rolled strip to obtain an aluminum foil material with a thickness of 0.008-0.010 mm; Step S4, slitting the aluminum foil material to obtain the aluminum foil for solid-state batteries.

2. The method for producing an aluminum foil for solid-state batteries according to claim 1, characterized by, The AlFe20 intermediate alloy is a wafer ingot; the element Fe in the AlFe20 intermediate alloy is derived from tinplate; the iron powder in the aluminum type iron agent is carbon steel molten slag removal atomized iron powder and is spherical.

3. The method for producing an aluminum foil for solid-state batteries according to claim 1, characterized by, In the step S1, the steps of the cast-rolling rolling method include, in sequence, preparation of the remelted aluminum ingot, melting, stirring, first refining, first standing, first slagging, addition of metal additives, second standing, second slagging, pouring, second refining, third slagging, third standing, degassing, filtering and cast-rolling; the metal additive in the addition of metal additives is element Si, element Fe and element Mn; Wherein, the melting, the stirring, the first refining, the first standing, the first slagging, the addition of metal additives, the second standing and the second slagging are all carried out in a melting furnace; the second refining, the third slagging, the third standing and the degassing are all carried out in a holding furnace; the pouring is pouring the aluminum liquid in the melting furnace after the second slagging into the holding furnace; The cast-rolling rolling method is a continuous preparation process, the frequency of the first refining is 3-4 h / time, and the frequency of the stirring is 2-3 h / time.

4. The method for producing an aluminum foil for solid-state batteries according to claim 3, characterized by, The filtering adopts double-stage filtering of a 60-mesh filter plate and a 70-mesh filter plate; the components and mass percentage of the 60-mesh filter plate and the 70-mesh filter plate are both: alumina = 85.00-86.00%, silicon dioxide = 5.00-6.00%, aluminum dihydrogen phosphate = 5.00-6.00%, and the balance is sintered product of NaO and CaO; the circumferential side of the 60-mesh filter plate and the 70-mesh filter plate is pasted with expanded cotton with a thickness of 4-6 mm, and the 60-mesh filter plate and the 70-mesh filter plate are preheated and kept at a temperature of 550-650℃ before filtering; the air pressure adopted by the 60-mesh filter plate is 1150-1250 Pa, and the air pressure adopted by the 70-mesh filter plate is 1400-1500 Pa.

5. The method for producing an aluminum foil for solid-state batteries according to claim 3, characterized by, The process of cast-rolling applies an electromagnetic field oscillation.

6. The method of producing an aluminum foil for solid-state batteries according to claim 1, characterized by, In the step S2, the cold rolling is performed by a cold rolling mill; the rolling oil used by the cold rolling mill is a rolling oil filtered by a filter cloth with a weight of 130 g / m 2 ; and the rolling oil used by the cold rolling mill has a reducing stabilizer with a weight of 0.20-0.40% of the rolling oil.

7. The method of producing an aluminum foil for solid-state batteries according to claim 1, characterized by, In the step S2, the cold rolling is obtained by multiple cold rolling passes; the last cold rolling pass has a coiling temperature less than 45℃, a rolling speed less than 500m / min, and an exit temperature less than 70℃.

8. The method of producing an aluminum foil for solid-state batteries according to claim 1, characterized by, In the step S3, the foil rolling is obtained by four foil rolling passes; the first foil rolling pass has a temperature of 120℃, the second foil rolling pass has a temperature of 100℃, the third foil rolling pass has a temperature of 80℃, and the fourth foil rolling pass has a temperature of 80℃.

9. The method of producing an aluminum foil for solid-state batteries according to claim 1, characterized by, In the step S4, the slitting is performed by a vertical slitting machine; the slitting knife of the vertical slitting machine is a tungsten steel disc knife; the vertical slitting machine is equipped with two corona devices, and the corona power of the corona device is 80-100kw; the slitting speed of the vertical slitting machine is 700-800m / min, and the height of the edge burr of the obtained aluminum foil for solid-state batteries is less than 0.001mm; the disc knife of the vertical slitting machine is lubricated with a lubricating liquid having a liquid inclination point of -25--30℃ before use; the convexity of the rubber roller in the vertical slitting machine is 0.100-0.150mm, and the roller surface pressure of the rubber roller in the vertical slitting machine is 2.0-2.5N.

10. An aluminum foil for solid-state batteries, characterized by, The aluminum foil for solid-state batteries is prepared by the method of any one of claims 1-9.

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